aboutsummaryrefslogblamecommitdiffstats
path: root/test/rfc7540_SUITE.erl
blob: 727ea0cfa43621f32ad43e2335998ba5deec681a (plain) (tree)
1
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
                                                             












































                                                                                                                  

                                          
























                                                                                                     
                                  












                                                                                                     
                                  




                                                                                           
                                                                   






                                                                                                     
                                  

                                                                                           
                                                                  

           
                                                         






                                                                                                     
                                  
                         
                                                                  









                                                                                                     
                                  













                                                                                                     
                                  





                                                                                   









                                                      







                                                                                                     
                                  

                                                                                           
                                 









                                                                                                             
                                  

                                                                                           
                                 











                                                                                                     
                                  

                                                                                           
                                 


                                                                                  




                                                                                      
                                                                         
                                                        









                                                                                                     
                                  

                                                                                           
                                 





                                                                                       


















                                                                                  








                                                                                                     
                                  

                                                                                           
                                 





                                                                                       


















                                                                                  








                                                                                                     
                                  

                                                                                           
                                 





                                                                                               


















                                                                                  








                                                                                                     
                                  

                                                                                           
                                 





                                                                                                    


















                                                                                  







                                                                                                     
                                  

                                                                                           
                                 















                                                                                                         
                                  

                                                                                           
                                 











                                                                                                 



























                                                                        
 






                                                                      
 








                                                                                                     
                                  

                                                                                           
                                 







                                                                                                 
                                                                                     
















                                                                              








                                                                                                     
                                  

                                                                                           
                                 





                                                                     


                                                                                  
























                                                                                                 




























































































































































































                                                                                                     
                                                        











                                                                                                     
                                                        











                                                                                                     
                                                        



























                                                                                                         

                                  

                                                                                                     







                                                                                                 






                                                                              







                                                                               






                                                                     
 
























                                                                                   




































































































































































































































































































































































































                                                                                                       







































































































































































































































































































                                                                                                                     
                                                                                   








                                                                                                   
                                                                                             














                                                                                                       
                                             
                                   
                                                                             



                                                     


                                                                           































































                                                                                        


















































                                                                                                    





















































































































































































































































































































































































































































































































































































                                                                                                     
%% Copyright (c) 2016-2017, Loïc Hoguin <[email protected]>
%%
%% Permission to use, copy, modify, and/or distribute this software for any
%% purpose with or without fee is hereby granted, provided that the above
%% copyright notice and this permission notice appear in all copies.
%%
%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

-module(rfc7540_SUITE).
-compile(export_all).

-import(ct_helper, [config/2]).
-import(ct_helper, [doc/1]).
-import(cowboy_test, [raw_open/1]).
-import(cowboy_test, [raw_send/2]).
-import(cowboy_test, [raw_recv_head/1]).
-import(cowboy_test, [raw_recv/3]).

all() -> [{group, clear}, {group, tls}].

groups() ->
	Modules = ct_helper:all(?MODULE),
	Clear = [M || M <- Modules, lists:sublist(atom_to_list(M), 4) =/= "alpn"] -- [prior_knowledge_reject_tls],
	TLS = [M || M <- Modules, lists:sublist(atom_to_list(M), 4) =:= "alpn"] ++ [prior_knowledge_reject_tls],
	[{clear, [parallel], Clear}, {tls, [parallel], TLS}].

init_per_group(Name = clear, Config) ->
	cowboy_test:init_http(Name = clear, #{
		env => #{dispatch => cowboy_router:compile(init_routes(Config))}
	}, Config);
init_per_group(Name = tls, Config) ->
	cowboy_test:init_http2(Name = tls, #{
		env => #{dispatch => cowboy_router:compile(init_routes(Config))}
	}, Config).

end_per_group(Name, _) ->
	ok = cowboy:stop_listener(Name).

init_routes(_) -> [
	{"localhost", [
		{"/", hello_h, []},
		{"/echo/:key", echo_h, []}
	]}
].

%% Starting HTTP/2 for "http" URIs.

http_upgrade_ignore_h2(Config) ->
	doc("An h2 token in an Upgrade field must be ignored. (RFC7540 3.2)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	{ok, <<"HTTP/1.1 200">>} = gen_tcp:recv(Socket, 12, 1000),
	ok.

http_upgrade_ignore_if_http_10(Config) ->
	doc("The Upgrade header must be ignored if part of an HTTP/1.0 request. (RFC7230 6.7)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.0\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	{ok, <<"HTTP/1.1 200">>} = gen_tcp:recv(Socket, 12, 1000),
	ok.

http_upgrade_ignore_missing_upgrade_in_connection(Config) ->
	doc("The Upgrade header must be listed in the "
		"Connection header field. (RFC7230 6.7)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	{ok, <<"HTTP/1.1 200">>} = gen_tcp:recv(Socket, 12, 1000),
	ok.

http_upgrade_ignore_missing_http2_settings_in_connection(Config) ->
	doc("The HTTP2-Settings header must be listed in the "
		"Connection header field. (RFC7540 3.2.1, RFC7230 6.7)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	{ok, <<"HTTP/1.1 200">>} = gen_tcp:recv(Socket, 12, 1000),
	ok.

http_upgrade_ignore_zero_http2_settings_header(Config) ->
	doc("The HTTP Upgrade request must include "
		"exactly one HTTP2-Settings header field (RFC7540 3.2, RFC7540 3.2.1)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"\r\n"]),
	{ok, <<"HTTP/1.1 200">>} = gen_tcp:recv(Socket, 12, 1000),
	ok.

http_upgrade_reject_two_http2_settings_header(Config) ->
	doc("The HTTP Upgrade request must include "
		"exactly one HTTP2-Settings header field (RFC7540 3.2, RFC7540 3.2.1)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	{ok, <<"HTTP/1.1 400">>} = gen_tcp:recv(Socket, 12, 1000),
	ok.

http_upgrade_reject_bad_http2_settings_header(Config) ->
	doc("The HTTP Upgrade request must include "
		"a valid HTTP2-Settings header field (RFC7540 3.2, RFC7540 3.2.1)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		%% We send a full SETTINGS frame on purpose.
		"HTTP2-Settings: ", base64:encode(cow_http2:settings(#{})), "\r\n",
		"\r\n"]),
	{ok, <<"HTTP/1.1 400">>} = gen_tcp:recv(Socket, 12, 1000),
	ok.

%% Match directly for now.
do_recv_101(Socket) ->
	{ok, <<
		"HTTP/1.1 101 Switching Protocols\r\n"
		"connection: Upgrade\r\n"
		"upgrade: h2c\r\n"
		"\r\n"
	>>} = gen_tcp:recv(Socket, 71, 1000),
	ok.

http_upgrade_101(Config) ->
	doc("A 101 response must be sent on successful upgrade "
		"to HTTP/2 when using the HTTP Upgrade mechanism. (RFC7540 3.2, RFC7230 6.7)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	ok = do_recv_101(Socket),
	ok.

http_upgrade_server_preface(Config) ->
	doc("The first frame after the upgrade must be a "
		"SETTINGS frame for the server connection preface. (RFC7540 3.2, RFC7540 3.5, RFC7540 6.5)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	ok = do_recv_101(Socket),
	%% Receive the server preface.
	{ok, << _:24, 4:8, 0:40 >>} = gen_tcp:recv(Socket, 9, 1000),
	ok.

http_upgrade_client_preface_timeout(Config) ->
	doc("Clients negotiating HTTP/2 and not sending a preface in "
		"a timely manner must be disconnected."),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	ok = do_recv_101(Socket),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% Receive the response to the initial HTTP/1.1 request.
	{ok, << HeadersSkipLen:24, 1:8, _:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, HeadersSkipLen, 1000),
	{ok, << DataSkipLen:24, 0:8, _:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, DataSkipLen, 1000),
	%% Do not send the preface. Wait for the server to disconnect us.
	{error, closed} = gen_tcp:recv(Socket, 9, 6000),
	ok.

http_upgrade_reject_missing_client_preface(Config) ->
	doc("Servers must treat an invalid connection preface as a "
		"connection error of type PROTOCOL_ERROR. (RFC7540 3.2, RFC7540 3.5)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	ok = do_recv_101(Socket),
	%% Send a SETTINGS frame directly instead of the proper preface.
	ok = gen_tcp:send(Socket, cow_http2:settings(#{})),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% We expect the server to close the connection when it receives a bad preface.
	%% The server may however have already started sending the response to the
	%% initial HTTP/1.1 request.
	Received = lists:reverse(lists:foldl(fun(_, Acc) ->
		case gen_tcp:recv(Socket, 9, 1000) of
			{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[headers|Acc];
			{ok, << SkipLen:24, 0:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[data|Acc];
			{error, _} ->
				[closed|Acc]
		end
	end, [], [1, 2, 3])),
	case Received of
		[closed|_] -> ok;
		[headers, closed|_] -> ok;
		[headers, data, closed] -> ok
	end.

http_upgrade_reject_invalid_client_preface(Config) ->
	doc("Servers must treat an invalid connection preface as a "
		"connection error of type PROTOCOL_ERROR. (RFC7540 3.2, RFC7540 3.5)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	ok = do_recv_101(Socket),
	%% Send a slightly incorrect preface.
	ok = gen_tcp:send(Socket, "PRI * HTTP/2.0\r\n\r\nSM: Value\r\n\r\n"),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% We expect the server to close the connection when it receives a bad preface.
	%% The server may however have already started sending the response to the
	%% initial HTTP/1.1 request.
	Received = lists:reverse(lists:foldl(fun(_, Acc) ->
		case gen_tcp:recv(Socket, 9, 1000) of
			{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[headers|Acc];
			{ok, << SkipLen:24, 0:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[data|Acc];
			{error, _} ->
				[closed|Acc]
		end
	end, [], [1, 2, 3])),
	case Received of
		[closed|_] -> ok;
		[headers, closed|_] -> ok;
		[headers, data, closed] -> ok
	end.

http_upgrade_reject_missing_client_preface_settings(Config) ->
	doc("Servers must treat an invalid connection preface as a "
		"connection error of type PROTOCOL_ERROR. (RFC7540 3.2, RFC7540 3.5)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	ok = do_recv_101(Socket),
	%% Send a valid preface sequence except followed by a PING instead of a SETTINGS frame.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:ping(0)]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% We expect the server to close the connection when it receives a bad preface.
	%% The server may however have already started sending the response to the
	%% initial HTTP/1.1 request.
	Received = lists:reverse(lists:foldl(fun(_, Acc) ->
		case gen_tcp:recv(Socket, 9, 1000) of
			{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[headers|Acc];
			{ok, << SkipLen:24, 0:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[data|Acc];
			{error, _} ->
				[closed|Acc]
		end
	end, [], [1, 2, 3])),
	case Received of
		[closed|_] -> ok;
		[headers, closed|_] -> ok;
		[headers, data, closed] -> ok
	end.

http_upgrade_reject_invalid_client_preface_settings(Config) ->
	doc("Servers must treat an invalid connection preface as a "
		"connection error of type PROTOCOL_ERROR. (RFC7540 3.2, RFC7540 3.5)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	ok = do_recv_101(Socket),
	%% Send a valid preface sequence except followed by a badly formed SETTINGS frame.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", << 0:24, 4:8, 0:9, 1:31 >>]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% We expect the server to close the connection when it receives a bad preface.
	%% The server may however have already started sending the response to the
	%% initial HTTP/1.1 request.
	Received = lists:reverse(lists:foldl(fun(_, Acc) ->
		case gen_tcp:recv(Socket, 9, 1000) of
			{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[headers|Acc];
			{ok, << SkipLen:24, 0:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[data|Acc];
			{error, _} ->
				[closed|Acc]
		end
	end, [], [1, 2, 3])),
	case Received of
		[closed|_] -> ok;
		[headers, closed|_] -> ok;
		[headers, data, closed] -> ok
	end.

http_upgrade_accept_client_preface_empty_settings(Config) ->
	doc("The SETTINGS frame in the client preface may be empty. (RFC7540 3.2, RFC7540 3.5)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	ok = do_recv_101(Socket),
	%% Send a valid preface sequence except followed by an empty SETTINGS frame.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% Receive the SETTINGS ack.
	{ok, << 0:24, 4:8, 1:8, 0:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	ok.

http_upgrade_client_preface_settings_ack_timeout(Config) ->
	doc("The SETTINGS frames sent by the client must be acknowledged. (RFC7540 3.5, RFC7540 6.5.3)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	ok = do_recv_101(Socket),
	%% Send a valid preface.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% Receive the SETTINGS ack.
	{ok, << 0:24, 4:8, 1:8, 0:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	%% Do not ack the server preface. Expect a GOAWAY with reason SETTINGS_TIMEOUT.
	{ok, << _:24, 7:8, _:72, 4:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

%% @todo We need a successful test with actual options in HTTP2-Settings.
%% SETTINGS_MAX_FRAME_SIZE is probably the easiest to test. The relevant
%% RFC quote is:
%%
%% 3.2.1
%%   A server decodes and interprets these values as it would any other
%%   SETTINGS frame. Explicit acknowledgement of these settings
%%   (Section 6.5.3) is not necessary, since a 101 response serves as
%%   implicit acknowledgement.

%% @todo We need to test an upgrade with a request body. It is probably
%% worth having a configuration value for how much we accept while still
%% upgrading (if too big, we would just stay on HTTP/1.1). We therefore
%% needs a test for when the body is small enough, and one for when the
%% body is larger than we accept. The relevant RFC quote is:
%%
%% 3.2
%%   Requests that contain a payload body MUST be sent in their entirety
%%   before the client can send HTTP/2 frames.  This means that a large
%%   request can block the use of the connection until it is completely
%%   sent.

%% @todo We should definitely have a test with OPTIONS. The relevant
%% RFC quote is:
%%
%% 3.2
%%   If concurrency of an initial request with subsequent requests is
%%   important, an OPTIONS request can be used to perform the upgrade to
%%   HTTP/2, at the cost of an additional round trip.

%% @todo If we ever handle priority, we need to check that the initial
%% HTTP/1.1 request has default priority. The relevant RFC quote is:
%%
%% 3.2
%%   The HTTP/1.1 request that is sent prior to upgrade is assigned a
%%   stream identifier of 1 (see Section 5.1.1) with default priority
%%   values (Section 5.3.5).

http_upgrade_response(Config) ->
	doc("A response must be sent to the initial HTTP/1.1 request "
		"after switching to HTTP/2. The response must use "
		"the stream identifier 1. (RFC7540 3.2)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	ok = do_recv_101(Socket),
	%% Send a valid preface.
	%% @todo Use non-empty SETTINGS here. Just because.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% Send the SETTINGS ack.
	ok = gen_tcp:send(Socket, cow_http2:settings_ack()),
	%% Receive the SETTINGS ack, and the response HEADERS and DATA (Stream ID 1).
	Received = lists:reverse(lists:foldl(fun(_, Acc) ->
		case gen_tcp:recv(Socket, 9, 1000) of
			{ok, << 0:24, 4:8, 1:8, 0:32 >>} ->
				[settings_ack|Acc];
			{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[headers|Acc];
			{ok, << SkipLen:24, 0:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[data|Acc]
		end
	end, [], [1, 2, 3])),
	case Received of
		[settings_ack, headers, data] -> ok;
		[headers, settings_ack, data] -> ok;
		[headers, data, settings_ack] -> ok
	end.

http_upgrade_response_half_closed(Config) ->
	doc("The stream for the initial HTTP/1.1 request is half-closed. (RFC7540 3.2)"),
	%% Try sending more data after the upgrade and get an error.
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	ok = do_recv_101(Socket),
	%% Send a valid preface followed by an unexpected DATA frame.
	ok = gen_tcp:send(Socket, [
		"PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n",
		cow_http2:settings(#{}),
		cow_http2:data(1, fin, <<"Unexpected DATA frame.">>)
	]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% Skip the SETTINGS ack, receive the response HEADERS, DATA and RST_STREAM (streamid 1).
	Received = lists:reverse(lists:foldl(fun(_, Acc) ->
		case gen_tcp:recv(Socket, 9, 1000) of
			{ok, << 0:24, 4:8, 1:8, 0:32 >>} ->
				Acc;
			{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[headers|Acc];
			{ok, << SkipLen:24, 0:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[data|Acc];
			{ok, << 4:24, 3:8, 0:8, 1:32 >>} ->
				%% We expect a STREAM_CLOSED reason.
				{ok, << 5:32 >>} = gen_tcp:recv(Socket, 4, 1000),
				[rst_stream|Acc];
			{error, _} ->
				%% Can be timeouts, ignore them.
				Acc
		end
	end, [], [1, 2, 3, 4])),
	case Received of
		[rst_stream] -> ok;
		[headers, rst_stream] -> ok;
		[headers, data, rst_stream] -> ok
	end.

%% Starting HTTP/2 for "https" URIs.

alpn_ignore_h2c(Config) ->
	doc("An h2c ALPN protocol identifier must be ignored. (RFC7540 3.3)"),
	{ok, Socket} = ssl:connect("localhost", config(port, Config),
		[{alpn_advertised_protocols, [<<"h2c">>, <<"http/1.1">>]}, binary, {active, false}]),
	{ok, <<"http/1.1">>} = ssl:negotiated_protocol(Socket),
	ok.

alpn_server_preface(Config) ->
	doc("The first frame must be a SETTINGS frame "
		"for the server connection preface. (RFC7540 3.3, RFC7540 3.5, RFC7540 6.5)"),
	{ok, Socket} = ssl:connect("localhost", config(port, Config),
		[{alpn_advertised_protocols, [<<"h2">>]}, binary, {active, false}]),
	{ok, <<"h2">>} = ssl:negotiated_protocol(Socket),
	%% Receive the server preface.
	{ok, << _:24, 4:8, 0:40 >>} = ssl:recv(Socket, 9, 1000),
	ok.

alpn_client_preface_timeout(Config) ->
	doc("Clients negotiating HTTP/2 and not sending a preface in "
		"a timely manner must be disconnected."),
	{ok, Socket} = ssl:connect("localhost", config(port, Config),
		[{alpn_advertised_protocols, [<<"h2">>]}, binary, {active, false}]),
	{ok, <<"h2">>} = ssl:negotiated_protocol(Socket),
	%% Receive the server preface.
	{ok, << Len:24 >>} = ssl:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = ssl:recv(Socket, 6 + Len, 1000),
	%% Do not send the preface. Wait for the server to disconnect us.
	{error, closed} = ssl:recv(Socket, 3, 6000),
	ok.

alpn_reject_missing_client_preface(Config) ->
	doc("Servers must treat an invalid connection preface as a "
		"connection error of type PROTOCOL_ERROR. (RFC7540 3.3, RFC7540 3.5)"),
	{ok, Socket} = ssl:connect("localhost", config(port, Config),
		[{alpn_advertised_protocols, [<<"h2">>]}, binary, {active, false}]),
	{ok, <<"h2">>} = ssl:negotiated_protocol(Socket),
	%% Send a SETTINGS frame directly instead of the proper preface.
	ok = ssl:send(Socket, cow_http2:settings(#{})),
	%% Receive the server preface.
	{ok, << Len:24 >>} = ssl:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = ssl:recv(Socket, 6 + Len, 1000),
	%% We expect the server to close the connection when it receives a bad preface.
	{error, closed} = ssl:recv(Socket, 3, 1000),
	ok.

alpn_reject_invalid_client_preface(Config) ->
	doc("Servers must treat an invalid connection preface as a "
		"connection error of type PROTOCOL_ERROR. (RFC7540 3.3, RFC7540 3.5)"),
	{ok, Socket} = ssl:connect("localhost", config(port, Config),
		[{alpn_advertised_protocols, [<<"h2">>]}, binary, {active, false}]),
	{ok, <<"h2">>} = ssl:negotiated_protocol(Socket),
	%% Send a slightly incorrect preface.
	ok = ssl:send(Socket, "PRI * HTTP/2.0\r\n\r\nSM: Value\r\n\r\n"),
	%% Receive the server preface.
	{ok, << Len:24 >>} = ssl:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = ssl:recv(Socket, 6 + Len, 1000),
	%% We expect the server to close the connection when it receives a bad preface.
	{error, closed} = ssl:recv(Socket, 3, 1000),
	ok.

alpn_reject_missing_client_preface_settings(Config) ->
	doc("Servers must treat an invalid connection preface as a "
		"connection error of type PROTOCOL_ERROR. (RFC7540 3.3, RFC7540 3.5)"),
	{ok, Socket} = ssl:connect("localhost", config(port, Config),
		[{alpn_advertised_protocols, [<<"h2">>]}, binary, {active, false}]),
	{ok, <<"h2">>} = ssl:negotiated_protocol(Socket),
	%% Send a valid preface sequence except followed by a PING instead of a SETTINGS frame.
	ok = ssl:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:ping(0)]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = ssl:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = ssl:recv(Socket, 6 + Len, 1000),
	%% We expect the server to close the connection when it receives a bad preface.
	{error, closed} = ssl:recv(Socket, 3, 1000),
	ok.

alpn_reject_invalid_client_preface_settings(Config) ->
	doc("Servers must treat an invalid connection preface as a "
		"connection error of type PROTOCOL_ERROR. (RFC7540 3.3, RFC7540 3.5)"),
	{ok, Socket} = ssl:connect("localhost", config(port, Config),
		[{alpn_advertised_protocols, [<<"h2">>]}, binary, {active, false}]),
	{ok, <<"h2">>} = ssl:negotiated_protocol(Socket),
	%% Send a valid preface sequence except followed by a badly formed SETTINGS frame.
	ok = ssl:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", << 0:24, 4:8, 0:9, 1:31 >>]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = ssl:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = ssl:recv(Socket, 6 + Len, 1000),
	%% We expect the server to close the connection when it receives a bad preface.
	{error, closed} = ssl:recv(Socket, 3, 1000),
	ok.

alpn_accept_client_preface_empty_settings(Config) ->
	doc("The SETTINGS frame in the client preface may be empty. (RFC7540 3.3, RFC7540 3.5)"),
	{ok, Socket} = ssl:connect("localhost", config(port, Config),
		[{alpn_advertised_protocols, [<<"h2">>]}, binary, {active, false}]),
	{ok, <<"h2">>} = ssl:negotiated_protocol(Socket),
	%% Send a valid preface sequence except followed by an empty SETTINGS frame.
	ok = ssl:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = ssl:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = ssl:recv(Socket, 6 + Len, 1000),
	%% Receive the SETTINGS ack.
	{ok, << 0:24, 4:8, 1:8, 0:32 >>} = ssl:recv(Socket, 9, 1000),
	ok.

alpn_client_preface_settings_ack_timeout(Config) ->
	doc("Failure to acknowledge the server's SETTINGS frame "
		"results in a SETTINGS_TIMEOUT connection error. (RFC7540 3.5, RFC7540 6.5.3)"),
	{ok, Socket} = ssl:connect("localhost", config(port, Config),
		[{alpn_advertised_protocols, [<<"h2">>]}, binary, {active, false}]),
	{ok, <<"h2">>} = ssl:negotiated_protocol(Socket),
	%% Send a valid preface.
	ok = ssl:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = ssl:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = ssl:recv(Socket, 6 + Len, 1000),
	%% Receive the SETTINGS ack.
	{ok, << 0:24, 4:8, 1:8, 0:32 >>} = ssl:recv(Socket, 9, 1000),
	%% Do not ack the server preface. Expect a GOAWAY with reason SETTINGS_TIMEOUT.
	{ok, << _:24, 7:8, _:72, 4:32 >>} = ssl:recv(Socket, 17, 6000),
	ok.

alpn(Config) ->
	doc("Successful ALPN negotiation. (RFC7540 3.3)"),
	{ok, Socket} = ssl:connect("localhost", config(port, Config),
		[{alpn_advertised_protocols, [<<"h2">>]}, binary, {active, false}]),
	{ok, <<"h2">>} = ssl:negotiated_protocol(Socket),
	%% Send a valid preface.
	%% @todo Use non-empty SETTINGS here. Just because.
	ok = ssl:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = ssl:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = ssl:recv(Socket, 6 + Len, 1000),
	%% Send the SETTINGS ack.
	ok = ssl:send(Socket, cow_http2:settings_ack()),
	%% Receive the SETTINGS ack.
	{ok, << 0:24, 4:8, 1:8, 0:32 >>} = ssl:recv(Socket, 9, 1000),
	%% Wait until after the SETTINGS ack timeout was supposed to trigger.
	receive after 6000 -> ok end,
	%% Send a PING.
	ok = ssl:send(Socket, cow_http2:ping(0)),
	%% Receive a PING ack back, indicating the connection is still up.
	{ok, << 8:24, 6:8, 0:7, 1:1, 0:96 >>} = ssl:recv(Socket, 17, 1000),
	ok.

%% Starting HTTP/2 with prior knowledge.

prior_knowledge_reject_tls(Config) ->
	doc("Implementations that support HTTP/2 over TLS must use ALPN. (RFC7540 3.4)"),
	{ok, Socket} = ssl:connect("localhost", config(port, Config), [binary, {active, false}]),
	%% Send a valid preface.
	ok = ssl:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% We expect the server to send an HTTP 400 error
	%% when trying to use HTTP/2 without going through ALPN negotiation.
	{ok, <<"HTTP/1.1 400">>} = ssl:recv(Socket, 12, 1000),
	ok.

prior_knowledge_server_preface(Config) ->
	doc("The first frame must be a SETTINGS frame "
		"for the server connection preface. (RFC7540 3.4, RFC7540 3.5, RFC7540 6.5)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	%% Send a valid preface.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% Receive the server preface.
	{ok, << _:24, 4:8, 0:40 >>} = gen_tcp:recv(Socket, 9, 1000),
	ok.

%% Note: the client preface timeout doesn't apply in this case,
%% so we don't test it. An HTTP/1.1 client that does not send
%% a request in a timely manner will get disconnected by the
%% HTTP protocol code, not by HTTP/2's.

%% Note: the test that starts by sending a SETTINGS frame is
%% redundant with tests sending garbage on the connection.
%% From the point of view of an HTTP/1.1 connection, a
%% SETTINGS frame is indistinguishable from garbage.

prior_knowledge_reject_invalid_client_preface(Config) ->
	doc("An incorrect preface is an invalid HTTP/1.1 request. (RFC7540 3.4)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	%% Send a slightly incorrect preface.
	ok = gen_tcp:send(Socket, "PRI * HTTP/2.0\r\n\r\nSM: Value\r\n\r\n"),
	%% We propagate to HTTP/2 after checking only the request-line.
	%% The server then sends its preface before checking the full client preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% We expect the server to close the connection when it receives a bad preface.
	{error, closed} = gen_tcp:recv(Socket, 9, 1000),
	ok.

prior_knowledge_reject_missing_client_preface_settings(Config) ->
	doc("Servers must treat an invalid connection preface as a "
		"connection error of type PROTOCOL_ERROR. (RFC7540 3.4, RFC7540 3.5)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	%% Send a valid preface sequence except followed by a PING instead of a SETTINGS frame.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:ping(0)]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% We expect the server to close the connection when it receives a bad preface.
	{error, closed} = gen_tcp:recv(Socket, 9, 1000),
	ok.

prior_knowledge_reject_invalid_client_preface_settings(Config) ->
	doc("Servers must treat an invalid connection preface as a "
		"connection error of type PROTOCOL_ERROR. (RFC7540 3.4, RFC7540 3.5)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	%% Send a valid preface sequence except followed by a badly formed SETTINGS frame.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", << 0:24, 4:8, 0:9, 1:31 >>]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% We expect the server to close the connection when it receives a bad preface.
	{error, closed} = gen_tcp:recv(Socket, 9, 1000),
	ok.

prior_knowledge_accept_client_preface_empty_settings(Config) ->
	doc("The SETTINGS frame in the client preface may be empty. (RFC7540 3.4, RFC7540 3.5)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	%% Send a valid preface sequence except followed by an empty SETTINGS frame.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% Receive the SETTINGS ack.
	{ok, << 0:24, 4:8, 1:8, 0:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	ok.

prior_knowledge_client_preface_settings_ack_timeout(Config) ->
	doc("The SETTINGS frames sent by the client must be acknowledged. (RFC7540 3.5, RFC7540 6.5.3)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	%% Send a valid preface.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% Receive the SETTINGS ack.
	{ok, << 0:24, 4:8, 1:8, 0:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	%% Do not ack the server preface. Expect a GOAWAY with reason SETTINGS_TIMEOUT.
	{ok, << _:24, 7:8, _:72, 4:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

%% Do a prior knowledge handshake.
do_handshake(Config) ->
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	%% Send a valid preface.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% Send the SETTINGS ack.
	ok = gen_tcp:send(Socket, cow_http2:settings_ack()),
	%% Receive the SETTINGS ack.
	{ok, << 0:24, 4:8, 1:8, 0:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, Socket}.

prior_knowledge(Config) ->
	doc("Streams can be initiated after a successful HTTP/2 connection "
		"with prior knowledge of server capabilities. (RFC7540 3.4)"),
	%% @todo Use non-empty SETTINGS here. Just because.
	{ok, Socket} = do_handshake(Config),
	%% Wait until after the SETTINGS ack timeout was supposed to trigger.
	receive after 6000 -> ok end,
	%% Send a PING.
	ok = gen_tcp:send(Socket, cow_http2:ping(0)),
	%% Receive a PING ack back, indicating the connection is still up.
	{ok, << 8:24, 6:8, 0:7, 1:1, 0:96 >>} = gen_tcp:recv(Socket, 17, 1000),
	ok.

%% @todo If we ever add an option to disable HTTP/2, we need to check
%% the following things:
%% * HTTP/1.1 Upgrade returns an HTTP/1.1 response (3.2)
%% * HTTP/1.1 Upgrade errors out if the client sends HTTP/2 frames
%%   without waiting for the 101 response (3.2, 3.5)
%% * Prior knowledge handshake fails (3.4)
%% * ALPN selects HTTP/1.1 (3.3)

%% Frame format.

ignore_unknown_frames(Config) ->
	doc("Frames of unknown type must be ignored and discarded. (RFC7540 4.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with a single DATA frame,
	%% and an unknown frame type interleaved.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, nofin, HeadersBlock),
		<< 10:24, 99:8, 0:40, 0:80 >>,
		cow_http2:data(1, fin, << 0:100/unit:8 >>)
	]),
	%% Receive a response with the same DATA frame.
	{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
	{ok, << 100:24, 0:8, 1:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, << 0:100/unit:8 >>} = gen_tcp:recv(Socket, 100, 1000),
	ok.

ignore_data_unknown_flags(Config) ->
	doc("Undefined DATA frame flags must be ignored. (RFC7540 4.1, RFC7540 6.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with a DATA frame with unknown flags.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, nofin, HeadersBlock),
		<< 100:24, 0:8,
			1:1, 1:1, 1:1, 1:1, %% Undefined.
			0:1, %% PADDED.
			1:1, 1:1, %% Undefined.
			1:1, %% END_STREAM.
			0:1, 1:31, 0:100/unit:8 >>
	]),
	%% Receive a response with the same DATA frame.
	{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
	{ok, << 100:24, 0:8, 1:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, << 0:100/unit:8 >>} = gen_tcp:recv(Socket, 100, 1000),
	ok.

ignore_headers_unknown_flags(Config) ->
	doc("Undefined HEADERS frame flags must be ignored. (RFC7540 4.1, RFC7540 6.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with a HEADERS frame with unknown flags.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	Len = iolist_size(HeadersBlock),
	ok = gen_tcp:send(Socket, [
		<< Len:24, 1:8,
			1:1, 1:1, %% Undefined.
			0:1, %% PRIORITY.
			1:1, %% Undefined.
			0:1, %% PADDED.
			1:1, %% END_HEADERS.
			1:1, %% Undefined.
			0:1, %% END_STREAM.
			0:1, 1:31 >>,
		HeadersBlock,
		cow_http2:data(1, fin, << 0:100/unit:8 >>)
	]),
	%% Receive a response with the same DATA frame.
	{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
	{ok, << 100:24, 0:8, 1:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, << 0:100/unit:8 >>} = gen_tcp:recv(Socket, 100, 1000),
	ok.

ignore_priority_unknown_flags(Config) ->
	doc("Undefined PRIORITY frame flags must be ignored. (RFC7540 4.1, RFC7540 6.3)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with an interleaved PRIORITY frame with unknown flags.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, nofin, HeadersBlock),
		<< 5:24, 2:8,
			1:1, 1:1, 1:1, 1:1, 1:1, 1:1, 1:1, 1:1, %% Undefined.
			0:1, 1:31, 0:1, 3:31, 0:8 >>,
		cow_http2:data(1, fin, << 0:100/unit:8 >>)
	]),
	%% Receive a response with the same DATA frame.
	{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
	{ok, << 100:24, 0:8, 1:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, << 0:100/unit:8 >>} = gen_tcp:recv(Socket, 100, 1000),
	ok.

ignore_rst_stream_unknown_flags(Config) ->
	doc("Undefined RST_STREAM frame flags must be ignored. (RFC7540 4.1, RFC7540 6.4)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request then cancel it with an RST_STREAM frame with unknown flags.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, nofin, HeadersBlock),
		<< 4:24, 3:8,
			1:1, 1:1, 1:1, 1:1, 1:1, 1:1, 1:1, 1:1, %% Undefined.
			0:1, 1:31, 8:32 >>,
		cow_http2:headers(3, nofin, HeadersBlock),
		cow_http2:data(3, fin, << 0:100/unit:8 >>)
	]),
	%% Receive a response with the same DATA frame.
	{ok, << SkipLen:24, 1:8, _:8, 3:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
	{ok, << 100:24, 0:8, 1:8, 3:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, << 0:100/unit:8 >>} = gen_tcp:recv(Socket, 100, 1000),
	ok.

ignore_settings_unknown_flags(Config) ->
	doc("Undefined SETTINGS frame flags must be ignored. (RFC7540 4.1, RFC7540 6.5)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a SETTINGS frame with unknown flags.
	ok = gen_tcp:send(Socket, << 6:24, 4:8,
		1:1, 1:1, 1:1, 1:1, 1:1, 1:1, 1:1, %% Undefined.
		0:1, %% ACK.
		0:32, 2:16, 0:32 >>),
	%% Receive a SETTINGS ack.
	{ok, << 0:24, 4:8, 0:7, 1:1, 0:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	ok.

ignore_push_promise_unknown_flags(Config) ->
	doc("Undefined PUSH_PROMISE frame flags must be ignored. (RFC7540 4.1, RFC7540 6.6)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PUSH_PROMISE frame with unknown flags.
	ok = gen_tcp:send(Socket, << 4:24, 5:8,
		1:1, 1:1, 1:1, 1:1, %% Undefined.
		0:1, %% PADDED.
		1:1, %% END_HEADERS.
		1:1, 1:1, %% Undefined.
		0:1, 1:31, 0:1, 3:31 >>
	),
	%% Receive a PROTOCOL_ERROR connection error.
	%%
	%% Note that it is not possible to distinguish between the expected
	%% result and the server rejecting PUSH_PROMISE frames.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

ignore_ping_unknown_flags(Config) ->
	doc("Undefined PING frame flags must be ignored. (RFC7540 4.1, RFC7540 6.7)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PING frame with unknown flags.
	ok = gen_tcp:send(Socket, << 8:24, 6:8,
		1:1, 1:1, 1:1, 1:1, 1:1, 1:1, 1:1, %% Undefined.
		0:1, %% ACK.
		0:32, 0:64 >>),
	%% Receive a PING ACK in return.
	{ok, << 8:24, 6:8, _:7, 1:1, _:32, 0:64 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

ignore_goaway_unknown_flags(Config) ->
	doc("Undefined GOAWAY frame flags must be ignored. (RFC7540 4.1, RFC7540 6.8)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a GOAWAY frame with unknown flags.
	ok = gen_tcp:send(Socket, << 8:24, 7:8,
		1:1, 1:1, 1:1, 1:1, 1:1, 1:1, 1:1, 1:1, %% Undefined.
		0:32, 0:64 >>),
	%% Receive a GOAWAY frame back.
	{ok, << _:24, 7:8, _:72, 0:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

ignore_window_update_unknown_flags(Config) ->
	doc("Undefined WINDOW_UPDATE frame flags must be ignored. (RFC7540 4.1, RFC7540 6.9)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a WINDOW_UPDATE frame with unknown flags.
	ok = gen_tcp:send(Socket, << 4:24, 8:8,
		1:1, 1:1, 1:1, 1:1, 1:1, 1:1, 1:1, 1:1, %% Undefined.
		0:32, 1000:32 >>),
	%% We expect no errors or replies, therefore we send a PING frame.
	ok = gen_tcp:send(Socket, cow_http2:ping(0)),
	%% And receive a PING ACK in return.
	{ok, << 8:24, 6:8, _:7, 1:1, _:32, 0:64 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

ignore_continuation_unknown_flags(Config) ->
	doc("Undefined CONTINUATION frame flags must be ignored. (RFC7540 4.1, RFC7540 6.10)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with a CONTINUATION frame with unknown flags.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	Len = iolist_size(HeadersBlock),
	ok = gen_tcp:send(Socket, [
		<< 0:24, 1:8, 0:8, 0:1, 1:31 >>,
		<< Len:24, 9:8,
			1:1, 1:1, 1:1, 1:1, 1:1, %% Undefined.
			1:1, %% END_HEADERS.
			1:1, 1:1, %% Undefined.
			0:1, 1:31 >>,
		HeadersBlock,
		cow_http2:data(1, fin, << 0:100/unit:8 >>)
	]),
	%% Receive a response with the same DATA frame.
	{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
	{ok, << 100:24, 0:8, 1:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, << 0:100/unit:8 >>} = gen_tcp:recv(Socket, 100, 1000),
	ok.

%% @todo Flags that have no defined semantics for
%% a particular frame type MUST be left unset (0x0) when sending. (RFC7540 4.1)

ignore_data_reserved_bit(Config) ->
	doc("Reserved 1-bit field of DATA frame must be ignored. (RFC7540 4.1, RFC7540 6.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with a DATA frame with the reserved bit set.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, nofin, HeadersBlock),
		<< 100:24, 0:8, 0:7, 1:1,
			1:1, %% Reserved bit.
			1:31, 0:100/unit:8 >>
	]),
	%% Receive a response with the same DATA frame.
	{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
	{ok, << 100:24, 0:8, 1:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, << 0:100/unit:8 >>} = gen_tcp:recv(Socket, 100, 1000),
	ok.

ignore_headers_reserved_bit(Config) ->
	doc("Reserved 1-bit field of HEADERS frame must be ignored. (RFC7540 4.1, RFC7540 6.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with a HEADERS frame with the reserved bit set.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	Len = iolist_size(HeadersBlock),
	ok = gen_tcp:send(Socket, [
		<< Len:24, 1:8, 0:5, 1:1, 0:2,
			1:1, %% Reserved bit.
			1:31 >>,
		HeadersBlock,
		cow_http2:data(1, fin, << 0:100/unit:8 >>)
	]),
	%% Receive a response with the same DATA frame.
	{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
	{ok, << 100:24, 0:8, 1:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, << 0:100/unit:8 >>} = gen_tcp:recv(Socket, 100, 1000),
	ok.

ignore_priority_reserved_bit(Config) ->
	doc("Reserved 1-bit field of PRIORITY frame must be ignored. (RFC7540 4.1, RFC7540 6.3)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with an interleaved PRIORITY frame with the reserved bit set.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, nofin, HeadersBlock),
		<< 5:24, 2:8, 0:8,
			1:1, %% Reserved bit.
			1:31, 0:1, 3:31, 0:8 >>,
		cow_http2:data(1, fin, << 0:100/unit:8 >>)
	]),
	%% Receive a response with the same DATA frame.
	{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
	{ok, << 100:24, 0:8, 1:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, << 0:100/unit:8 >>} = gen_tcp:recv(Socket, 100, 1000),
	ok.

ignore_rst_stream_reserved_bit(Config) ->
	doc("Reserved 1-bit field of RST_STREAM frame must be ignored. (RFC7540 4.1, RFC7540 6.4)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request then cancel it with an RST_STREAM frame with the reserved bit set.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, nofin, HeadersBlock),
		<< 4:24, 3:8, 0:8,
			1:1, %% Reserved bit.
			1:31, 8:32 >>,
		cow_http2:headers(3, nofin, HeadersBlock),
		cow_http2:data(3, fin, << 0:100/unit:8 >>)
	]),
	%% Receive a response with the same DATA frame.
	{ok, << SkipLen:24, 1:8, _:8, 3:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
	{ok, << 100:24, 0:8, 1:8, 3:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, << 0:100/unit:8 >>} = gen_tcp:recv(Socket, 100, 1000),
	ok.

ignore_settings_reserved_bit(Config) ->
	doc("Reserved 1-bit field of SETTINGS frame must be ignored. (RFC7540 4.1, RFC7540 6.5)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a SETTINGS frame with the reserved bit set.
	ok = gen_tcp:send(Socket, << 6:24, 4:8, 0:8,
		1:1, %% Reserved bit.
		0:31, 2:16, 0:32 >>),
	%% Receive a SETTINGS ack.
	{ok, << 0:24, 4:8, 0:7, 1:1, 0:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	ok.

ignore_push_promise_reserved_bit(Config) ->
	doc("Reserved 1-bit field of PUSH_PROMISE frame must be ignored. (RFC7540 4.1, RFC7540 6.6)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PUSH_PROMISE frame with the reserved bit set.
	ok = gen_tcp:send(Socket, << 4:24, 5:8, 0:5, 1:1, 0:2,
		1:1, %% Reserved bit.
		1:31, 0:1, 3:31 >>
	),
	%% Receive a PROTOCOL_ERROR connection error.
	%%
	%% Note that it is not possible to distinguish between the expected
	%% result and the server rejecting PUSH_PROMISE frames.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

ignore_ping_reserved_bit(Config) ->
	doc("Reserved 1-bit field of PING frame must be ignored. (RFC7540 4.1, RFC7540 6.7)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PING frame with the reserved bit set.
	ok = gen_tcp:send(Socket, << 8:24, 6:8, 0:8,
		1:1, %% Reserved bit.
		0:31, 0:64 >>),
	%% Receive a PING ACK in return.
	{ok, << 8:24, 6:8, _:7, 1:1, _:32, 0:64 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

ignore_goaway_reserved_bit(Config) ->
	doc("Reserved 1-bit field of GOAWAY frame must be ignored. (RFC7540 4.1, RFC7540 6.8)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a GOAWAY frame with the reserved bit set.
	ok = gen_tcp:send(Socket, << 8:24, 7:8, 0:8,
		1:1, %% Reserved bit.
		0:31, 0:64 >>),
	%% Receive a GOAWAY frame back.
	{ok, << _:24, 7:8, _:72, 0:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

ignore_window_update_reserved_bit(Config) ->
	doc("Reserved 1-bit field of WINDOW_UPDATE frame must be ignored. (RFC7540 4.1, RFC7540 6.9)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a WINDOW_UPDATE frame with the reserved bit set.
	ok = gen_tcp:send(Socket, << 4:24, 8:8, 0:8,
		1:1, %% Reserved bit.
		0:31, 1000:32 >>),
	%% We expect no errors or replies, therefore we send a PING frame.
	ok = gen_tcp:send(Socket, cow_http2:ping(0)),
	%% And receive a PING ACK in return.
	{ok, << 8:24, 6:8, _:7, 1:1, _:32, 0:64 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

ignore_continuation_reserved_bit(Config) ->
	doc("Reserved 1-bit field of CONTINUATION frame must be ignored. (RFC7540 4.1, RFC7540 6.10)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with a CONTINUATION frame with the reserved bit set.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	Len = iolist_size(HeadersBlock),
	ok = gen_tcp:send(Socket, [
		<< 0:24, 1:8, 0:8, 0:1, 1:31 >>,
		<< Len:24, 9:8, 0:5, 1:1, 0:2,
			1:1, %% Reserved bit.
			1:31 >>,
		HeadersBlock,
		cow_http2:data(1, fin, << 0:100/unit:8 >>)
	]),
	%% Receive a response with the same DATA frame.
	{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
	{ok, << 100:24, 0:8, 1:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, << 0:100/unit:8 >>} = gen_tcp:recv(Socket, 100, 1000),
	ok.

%% @todo The reserved 1-bit field MUST remain unset (0x0) when sending. (RFC7540 4.1)

%% Frame size.

max_frame_size_allow_exactly_default(Config) ->
	doc("All implementations must allow frame sizes of at least 16384. (RFC7540 4.1, RFC7540 4.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with a DATA frame of exactly 16384 bytes.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, nofin, HeadersBlock),
		cow_http2:data(1, fin, << 0:16384/unit:8 >>)
	]),
	%% Receive a response with the same DATA frame.
	{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
	{ok, << 16384:24, 0:8, 1:8, 1:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	{ok, << 0:16384/unit:8 >>} = gen_tcp:recv(Socket, 16384, 1000),
	ok.

max_frame_size_reject_larger_than_default(Config) ->
	doc("A FRAME_SIZE_ERROR connection error must be sent when receiving "
		"frames larger than the default 16384 length. (RFC7540 4.1, RFC7540 4.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with a DATA frame larger than 16384 bytes.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, nofin, HeadersBlock),
		cow_http2:data(1, fin, << 0:16385/unit:8 >>)
	]),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

%% @todo We need configurable SETTINGS in Cowboy for these tests.
%%	max_frame_size_config_reject_too_small(Config) ->
%%		doc("SETTINGS_MAX_FRAME_SIZE configuration values smaller than "
%%			"16384 must be rejected. (RFC7540 6.5.2)"),
%%		%% @todo This requires us to have a configurable SETTINGS in Cowboy.
%%		todo.
%%
%%	max_frame_size_config_reject_too_large(Config) ->
%%		doc("SETTINGS_MAX_FRAME_SIZE configuration values larger than "
%%			"16777215 must be rejected. (RFC7540 6.5.2)"),
%%		%% @todo This requires us to have a configurable SETTINGS in Cowboy.
%%		todo.
%%
%%	max_frame_size_allow_exactly_custom(Config) ->
%%		doc("An endpoint that sets SETTINGS_MAX_FRAME_SIZE must allow frames "
%%			"of up to that size. (RFC7540 4.2, RFC7540 6.5.2)"),
%%		%% @todo This requires us to have a configurable SETTINGS in Cowboy.
%%		todo.
%%
%%	max_frame_size_reject_larger_than_custom(Config) ->
%%		doc("An endpoint that sets SETTINGS_MAX_FRAME_SIZE must reject frames "
%%			"of up to that size with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.5.2)"),
%%		%% @todo This requires us to have a configurable SETTINGS in Cowboy.
%%		todo.

%% @todo How do I test this?
%%
%%	max_frame_size_client_default_respect_limits(Config) ->
%%		doc("The server must not send frame sizes of more "
%%			"than 16384 by default. (RFC7540 4.1, RFC7540 4.2)"),

%% This is about the client sending a SETTINGS frame.
max_frame_size_client_override_reject_too_small(Config) ->
	doc("A SETTINGS_MAX_FRAME_SIZE smaller than 16384 must be rejected "
		"with a PROTOCOL_ERROR connection error. (RFC7540 6.5.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a SETTINGS frame with a SETTINGS_MAX_FRAME_SIZE lower than 16384.
	ok = gen_tcp:send(Socket, << 6:24, 4:8, 0:40, 5:16, 16383:32 >>),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

%% This is about the client sending a SETTINGS frame.
max_frame_size_client_override_reject_too_large(Config) ->
	doc("A SETTINGS_MAX_FRAME_SIZE larger than 16777215 must be rejected "
		"with a PROTOCOL_ERROR connection error. (RFC7540 6.5.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a SETTINGS frame with a SETTINGS_MAX_FRAME_SIZE larger than 16777215.
	ok = gen_tcp:send(Socket, << 6:24, 4:8, 0:40, 5:16, 16777216:32 >>),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

%% @todo How do I test this?
%%
%%	max_frame_size_client_custom_respect_limits(Config) ->
%%		doc("The server must not send frame sizes of more than "
%%			"client's advertised limits. (RFC7540 4.1, RFC7540 4.2)"),

%% I am using FRAME_SIZE_ERROR here because the information in the
%% frame header tells us this frame is at least 1 byte long, while
%% the given length is smaller; i.e. it is too small to contain
%% mandatory frame data (the pad length).

data_reject_frame_size_0_padded_flag(Config) ->
	doc("DATA frames of size 0 with the PADDED flag set must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with an incorrect padded DATA frame size.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, nofin, HeadersBlock),
		<< 0:24, 0:8, 0:4, 1:1, 0:2, 1:1, 0:1, 1:31 >>
	]),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

%% This case on the other hand is noted specifically in the RFC
%% as being a PROTOCOL_ERROR. It can be thought of as the Pad Length
%% being incorrect, rather than the frame size.

data_reject_frame_size_too_small_padded_flag(Config) ->
	doc("DATA frames with Pad Length >= Length must be rejected "
		"with a PROTOCOL_ERROR connection error. (RFC7540 6.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a POST request with an incorrect padded DATA frame size.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"POST">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/echo/read_body">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, nofin, HeadersBlock),
		<< 10:24, 0:8, 0:4, 1:1, 0:2, 1:1, 0:1, 1:31, 10:8, 0:80  >>
	]),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

headers_reject_frame_size_0_padded_flag(Config) ->
	doc("HEADERS frames of size 0 with the PADDED flag set must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a padded HEADERS frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 0:24, 1:8, 0:4, 1:1, 0:2, 1:1, 0:1, 1:31 >>),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

headers_reject_frame_size_too_small_padded_flag(Config) ->
	doc("HEADERS frames with no priority flag and Pad Length >= Length "
		"must be rejected with a PROTOCOL_ERROR connection error. (RFC7540 6.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a padded HEADERS frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 10:24, 1:8, 0:4, 1:1, 0:2, 1:1, 0:1, 1:31, 10:8, 0:80 >>),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

headers_reject_frame_size_too_small_priority_flag(Config) ->
	doc("HEADERS frames of size smaller than 5 with the PRIORITY flag set must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame with priority set and an incorrect size.
	ok = gen_tcp:send(Socket, << 4:24, 1:8,
		0:2, 1:1, 0:4, 1:1, 0:1, 1:31, 0:1, 3:31, 0:8 >>),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

headers_reject_frame_size_5_padded_and_priority_flags(Config) ->
	doc("HEADERS frames of size smaller than 6 with the PADDED "
		"and PRIORITY flags set must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a padded HEADERS frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 5:24, 1:8,
		0:2, 1:1, 0:1, 1:1, 0:2, 1:1, 0:1, 1:31, 0:8, 0:1, 3:31, 0:8 >>),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

headers_reject_frame_size_too_small_padded_and_priority_flags(Config) ->
	doc("HEADERS frames of size smaller than Length+6 with the PADDED and PRIORITY flags set "
		"must be rejected with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a padded HEADERS frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 15:24, 1:8,
		0:2, 1:1, 0:1, 1:1, 0:2, 1:1, 0:1, 1:31, 10:8, 0:1, 3:31, 0:8, 0:80 >>),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

priority_reject_frame_size_too_small(Config) ->
	doc("PRIORITY frames of size smaller than 5 must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.3)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PRIORITY frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 4:24, 2:8, 0:9, 1:31, 0:1, 3:31, 0:8 >>),
	%% Receive a FRAME_SIZE_ERROR stream error.
	{ok, << _:24, 3:8, _:40, 6:32 >>} = gen_tcp:recv(Socket, 13, 6000),
	ok.

priority_reject_frame_size_too_large(Config) ->
	doc("PRIORITY frames of size larger than 5 must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.3)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PRIORITY frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 6:24, 2:8, 0:9, 1:31, 0:1, 3:31, 0:16 >>),
	%% Receive a FRAME_SIZE_ERROR stream error.
	{ok, << _:24, 3:8, _:40, 6:32 >>} = gen_tcp:recv(Socket, 13, 6000),
	ok.

rst_stream_reject_frame_size_too_small(Config) ->
	doc("RST_STREAM frames of size smaller than 4 must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.4)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a request and reset it immediately.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, fin, HeadersBlock),
		<< 3:24, 3:8, 0:9, 1:31, 8:32 >>
	]),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

rst_stream_reject_frame_size_too_large(Config) ->
	doc("RST_STREAM frames of size larger than 4 must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.4)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a request and reset it immediately.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, [
		cow_http2:headers(1, fin, HeadersBlock),
		<< 5:24, 3:8, 0:9, 1:31, 8:32 >>
	]),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

settings_reject_bad_frame_size(Config) ->
	doc("SETTINGS frames must have a size multiple of 6 or be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.5)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a SETTINGS frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 5:24, 4:8, 0:40, 1:16, 4096:32 >>),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

settings_ack_reject_non_empty_frame_size(Config) ->
	doc("SETTINGS frames with the ACK flag set and a non-empty payload "
		"must be rejected with a FRAME_SIZE_ERROR connection error (RFC7540 4.2, RFC7540 6.5)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	%% Send a valid preface.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% Send a SETTINGS ack with a payload.
	ok = gen_tcp:send(Socket, << 6:24, 4:8, 0:7, 1:1, 0:32, 1:16, 4096:32 >>),
	%% Receive the SETTINGS ack.
	{ok, << 0:24, 4:8, 1:8, 0:32 >>} = gen_tcp:recv(Socket, 9, 1000),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

%% Note that clients are not supposed to send PUSH_PROMISE frames.
%% However when they do, we need to be able to parse it in order
%% to reject it, and so these errors may still occur.

push_promise_reject_frame_size_too_small(Config) ->
	doc("PUSH_PROMISE frames of size smaller than 4 must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.6)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PUSH_PROMISE frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 3:24, 5:8, 0:5, 1:1, 0:3, 1:31, 0:1, 3:31 >>),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

push_promise_reject_frame_size_4_padded_flag(Config) ->
	doc("PUSH_PROMISE frames of size smaller than 5 with the PADDED flag set must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.6)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PUSH_PROMISE frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 4:24, 5:8, 0:4, 1:1, 1:1, 0:3, 1:31, 0:1, 0:8, 3:31 >>),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

push_promise_reject_frame_size_too_small_padded_flag(Config) ->
	doc("PUSH_PROMISE frames of size smaller than Length+5 with the PADDED flag set "
		"must be rejected with a PROTOCOL_ERROR connection error. (RFC7540 4.2, RFC7540 6.6)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PUSH_PROMISE frame with an incorrect size.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	Len = 14 + iolist_size(HeadersBlock),
	ok = gen_tcp:send(Socket, [
		<< Len:24, 5:8, 0:4, 1:1, 1:1, 0:3, 1:31, 10:8, 0:1, 3:31 >>,
		HeadersBlock,
		<< 0:80 >>
	]),
	%% Receive a PROTOCOL_ERROR connection error.
	%%
	%% Note that it is not possible to distinguish between a Pad Length
	%% error and the server rejecting PUSH_PROMISE frames.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

ping_reject_frame_size_too_small(Config) ->
	doc("PING frames of size smaller than 8 must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.7)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PING frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 7:24, 6:8, 0:40, 0:56 >>),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

ping_reject_frame_size_too_large(Config) ->
	doc("PING frames of size larger than 8 must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.7)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PING frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 9:24, 6:8, 0:40, 0:72 >>),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

goaway_reject_frame_size_too_small(Config) ->
	doc("GOAWAY frames of size smaller than 8 must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.8)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a GOAWAY frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 7:24, 7:8, 0:40, 0:56 >>),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

goaway_allow_frame_size_too_large(Config) ->
	doc("GOAWAY frames of size larger than 8 must be allowed. (RFC7540 6.8)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a GOAWAY frame with debug data.
	ok = gen_tcp:send(Socket, << 12:24, 7:8, 0:40, 0:64, 99999:32 >>),
	%% Receive a GOAWAY frame back.
	{ok, << _:24, 7:8, _:72, 0:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

window_update_reject_frame_size_too_small(Config) ->
	doc("WINDOW_UPDATE frames of size smaller than 4 must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.9)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a WINDOW_UPDATE frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 3:24, 8:8, 0:40, 1000:24 >>),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

window_update_reject_frame_size_too_large(Config) ->
	doc("WINDOW_UPDATE frames of size larger than 4 must be rejected "
		"with a FRAME_SIZE_ERROR connection error. (RFC7540 4.2, RFC7540 6.9)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a WINDOW_UPDATE frame with an incorrect size.
	ok = gen_tcp:send(Socket, << 5:24, 8:8, 0:40, 1000:40 >>),
	%% Receive a FRAME_SIZE_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 6:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

%% Note: There is no particular limits on the size of CONTINUATION frames,
%% they can go from 0 to SETTINGS_MAX_FRAME_SIZE.

%% Header compression and decompression.

headers_compression_error(Config) ->
	doc("A decoding error in a HEADERS frame's header block must be rejected "
		"with a COMPRESSION_ERROR connection error. (RFC7540 4.3, RFC7540 6.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame with an invalid header block.
	ok = gen_tcp:send(Socket, << 10:24, 1:8, 0:5, 1:1, 0:1, 1:1, 0:1, 1:31, 0:10/unit:8 >>),
	%% Receive a COMPRESSION_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 9:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

continuation_compression_error(Config) ->
	doc("A decoding error in a CONTINUATION frame's header block must be rejected "
		"with a COMPRESSION_ERROR connection error. (RFC7540 4.3, RFC7540 6.10)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a CONTINUATION frame with an invalid header block.
	ok = gen_tcp:send(Socket, [
		<< 0:24, 1:8, 0:7, 1:1, 0:1, 1:31 >>,
		<< 10:24, 9:8, 0:5, 1:1, 0:3, 1:31, 0:10/unit:8 >>
	]),
	%% Receive a COMPRESSION_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 9:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

continuation_with_frame_interleaved_error(Config) ->
	doc("Frames interleaved in a header block must be rejected "
		"with a PROTOCOL_ERROR connection error. (RFC7540 4.3, RFC7540 6.2, RFC7540 6.10)"),
	{ok, Socket} = do_handshake(Config),
	%% Send an unterminated HEADERS frame followed by a PING frame.
	ok = gen_tcp:send(Socket, [
		<< 0:24, 1:8, 0:7, 1:1, 0:1, 1:31 >>,
		cow_http2:ping(0)
	]),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

continuation_wrong_stream_error(Config) ->
	doc("CONTINUATION frames with an incorrect stream identifier must be rejected "
		"with a PROTOCOL_ERROR connection error. (RFC7540 4.3, RFC7540 6.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send an unterminated HEADERS frame followed by a CONTINUATION frame for another stream.
	ok = gen_tcp:send(Socket, [
		<< 0:24, 1:8, 0:7, 1:1, 0:1, 1:31 >>,
		<< 0:24, 9:8, 0:9, 3:31 >>
	]),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

%% Stream states.

idle_stream_reject_data(Config) ->
	doc("DATA frames received on an idle stream must be rejected "
		"with a PROTOCOL_ERROR connection error. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a DATA frame on an idle stream.
	ok = gen_tcp:send(Socket, cow_http2:data(1, fin, <<"Unexpected DATA frame.">>)),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

idle_stream_accept_headers(Config) ->
	doc("HEADERS frames received on an idle stream must be accepted. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame on an idle stream.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, fin, HeadersBlock)),
	%% Receive a HEADERS frame as a response.
	{ok, << _:24, 1:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	ok.

idle_stream_accept_priority(Config) ->
	doc("PRIORITY frames received on an idle stream must be accepted. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PRIORITY frame on an idle stream.
	ok = gen_tcp:send(Socket, cow_http2:priority(1, shared, 3, 123)),
	%% Receive no error.
	{error, timeout} = gen_tcp:recv(Socket, 7, 1000),
	%% Send a HEADERS frame on the same stream.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, fin, HeadersBlock)),
	%% Receive a HEADERS frame as a response.
	{ok, << _:24, 1:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	ok.

idle_stream_reject_rst_stream(Config) ->
	doc("RST_STREAM frames received on an idle stream must be rejected "
		"with a PROTOCOL_ERROR connection error. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send an RST_STREAM frame on an idle stream.
	ok = gen_tcp:send(Socket, cow_http2:rst_stream(1, no_error)),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

idle_stream_reject_push_promise(Config) ->
	doc("PUSH_PROMISE frames received on an idle stream must be rejected "
		"with a PROTOCOL_ERROR connection error. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a PUSH_PROMISE frame on an idle stream.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:push_promise(1, 3, HeadersBlock)),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

idle_stream_reject_window_update(Config) ->
	doc("WINDOW_UPDATE frames received on an idle stream must be rejected "
		"with a PROTOCOL_ERROR connection error. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a WINDOW_UPDATE frame on an idle stream.
	ok = gen_tcp:send(Socket, cow_http2:window_update(1, 12345)),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

%reserved (local) - after sending PUSH_PROMISE:
%      An endpoint MUST NOT send any type of frame other than HEADERS,
%      RST_STREAM, or PRIORITY in this state.
%%% how to test this?
%
%      A PRIORITY or WINDOW_UPDATE frame MAY be received in this state.
%      Receiving any type of frame other than RST_STREAM, PRIORITY, or
%      WINDOW_UPDATE on a stream in this state MUST be treated as a
%      connection error (Section 5.4.1) of type PROTOCOL_ERROR.
%%% we need to use a large enough file for this
%
%reserved_local_reject_data
%reserved_local_reject_headers
%reserved_local_accept_priority
%reserved_local_accept_rst_stream
%reserved_local_reject_push_promise %% do we even care? we reject it always
%reserved_local_accept_window_update
%
%half-closed (remote):
%      If an endpoint receives additional frames, other than
%      WINDOW_UPDATE, PRIORITY, or RST_STREAM, for a stream that is in
%      this state, it MUST respond with a stream error (Section 5.4.2) of
%      type STREAM_CLOSED.

half_closed_remote_reject_data(Config) ->
	doc("DATA frames received on a half-closed (remote) stream must be rejected "
		"with a STREAM_CLOSED stream error. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame with the FIN flag set.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, fin, HeadersBlock)),
	%% Send a DATA frame on that now half-closed (remote) stream.
	ok = gen_tcp:send(Socket, cow_http2:data(1, fin, <<"Unexpected DATA frame.">>)),
	%% Receive a STREAM_CLOSED stream error.
	{ok, << _:24, 3:8, _:8, 1:32, 5:32 >>} = gen_tcp:recv(Socket, 13, 6000),
	ok.

half_closed_remote_reject_headers(Config) ->
	doc("HEADERS frames received on a half-closed (remote) stream must be rejected "
		"with a STREAM_CLOSED stream error. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame with the FIN flag set.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, fin, HeadersBlock)),
	%% Send a HEADERS frame on that now half-closed (remote) stream.
	ok = gen_tcp:send(Socket, cow_http2:headers(1, fin, HeadersBlock)),
	%% Receive a STREAM_CLOSED stream error.
	{ok, << _:24, 3:8, _:8, 1:32, 5:32 >>} = gen_tcp:recv(Socket, 13, 6000),
	ok.

half_closed_remote_accept_priority(Config) ->
	doc("PRIORITY frames received on a half-closed stream must be accepted. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame with the FIN flag set.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, fin, HeadersBlock)),
	%% Send a PRIORITY frame on that now half-closed (remote) stream.
	ok = gen_tcp:send(Socket, cow_http2:priority(1, shared, 3, 123)),
	%% Receive a HEADERS frame as a response.
	{ok, << _:24, 1:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	ok.

half_closed_remote_accept_rst_stream(Config) ->
	doc("RST_STREAM frames received on a half-closed stream must be accepted. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame with the FIN flag set.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, fin, HeadersBlock)),
	%% Send an RST_STREAM frame on that now half-closed (remote) stream.
	ok = gen_tcp:send(Socket, cow_http2:rst_stream(1, no_error)),
	%% Receive nothing back.
	{error, timeout} = gen_tcp:recv(Socket, 9, 6000),
	ok.

%% half_closed_remote_reject_push_promise
%%
%% We respond to all PUSH_PROMISE frames with a PROTOCOL_ERROR connection error
%% because PUSH is disabled in that direction. We therefore cannot test other
%% error conditions.

half_closed_remote_accept_window_update(Config) ->
	doc("WINDOW_UPDATE frames received on a half-closed stream must be accepted. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame with the FIN flag set.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, fin, HeadersBlock)),
	%% Send a WINDOW_UPDATE frame on that now half-closed (remote) stream.
	ok = gen_tcp:send(Socket, cow_http2:window_update(1, 12345)),
	%% Receive a HEADERS frame as a response.
	{ok, << _:24, 1:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	ok.

rst_stream_closed_reject_data(Config) ->
	doc("DATA frames received on a stream closed via RST_STREAM must be rejected "
		"with a STREAM_CLOSED stream error. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, nofin, HeadersBlock)),
	%% Send an RST_STREAM frame to close the stream.
	ok = gen_tcp:send(Socket, cow_http2:rst_stream(1, cancel)),
	%% Send a DATA frame on the now RST_STREAM closed stream.
	ok = gen_tcp:send(Socket, cow_http2:data(1, fin, <<"Unexpected DATA frame.">>)),
	%% Receive a STREAM_CLOSED stream error.
	{ok, << _:24, 3:8, _:8, 1:32, 5:32 >>} = gen_tcp:recv(Socket, 13, 6000),
	ok.

rst_stream_closed_reject_headers(Config) ->
	doc("HEADERS frames received on a stream closed via RST_STREAM must be rejected "
		"with a STREAM_CLOSED stream error. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, nofin, HeadersBlock)),
	%% Send an RST_STREAM frame to close the stream.
	ok = gen_tcp:send(Socket, cow_http2:rst_stream(1, cancel)),
	%% Send a HEADERS frame on the now RST_STREAM closed stream.
	ok = gen_tcp:send(Socket, cow_http2:headers(1, nofin, HeadersBlock)),
	%% Receive a STREAM_CLOSED stream error.
	{ok, << _:24, 3:8, _:8, 1:32, 5:32 >>} = gen_tcp:recv(Socket, 13, 6000),
	ok.

rst_stream_closed_accept_priority(Config) ->
	doc("PRIORITY frames received on a stream closed via RST_STREAM "
		"must be accepted. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, nofin, HeadersBlock)),
	%% Send an RST_STREAM frame to close the stream.
	ok = gen_tcp:send(Socket, cow_http2:rst_stream(1, cancel)),
	%% Send a PRIORITY frame on that now RST_STREAM closed stream.
	ok = gen_tcp:send(Socket, cow_http2:priority(1, shared, 3, 123)),
	%% Receive nothing back.
	{error, timeout} = gen_tcp:recv(Socket, 9, 6000),
	ok.

rst_stream_closed_ignore_rst_stream(Config) ->
	doc("RST_STREAM frames received on a stream closed via RST_STREAM "
		"must be ignored to avoid looping. (RFC7540 5.1, RFC7540 5.4.2)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, nofin, HeadersBlock)),
	%% Send an RST_STREAM frame to close the stream.
	ok = gen_tcp:send(Socket, cow_http2:rst_stream(1, cancel)),
	%% Send an extra RST_STREAM.
	ok = gen_tcp:send(Socket, cow_http2:rst_stream(1, cancel)),
	%% Receive nothing back.
	{error, timeout} = gen_tcp:recv(Socket, 9, 6000),
	ok.

%% rst_stream_closed_reject_push_promise
%%
%% We respond to all PUSH_PROMISE frames with a PROTOCOL_ERROR connection error
%% because PUSH is disabled in that direction. We therefore cannot test other
%% error conditions.

rst_stream_closed_reject_window_update(Config) ->
	doc("WINDOW_UPDATE frames received on a stream closed via RST_STREAM "
		"must be rejected with a STREAM_CLOSED stream error. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, nofin, HeadersBlock)),
	%% Send an RST_STREAM frame to close the stream.
	ok = gen_tcp:send(Socket, cow_http2:rst_stream(1, cancel)),
	%% Send a WINDOW_UPDATE frame on the now RST_STREAM closed stream.
	ok = gen_tcp:send(Socket, cow_http2:window_update(1, 12345)),
	%% Receive a STREAM_CLOSED stream error.
	{ok, << _:24, 3:8, _:8, 1:32, 5:32 >>} = gen_tcp:recv(Socket, 13, 6000),
	ok.

stream_closed_reject_data(Config) ->
	doc("DATA frames received on a stream closed normally must be rejected "
		"with a STREAM_CLOSED connection error. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, fin, HeadersBlock)),
	%% Receive the response.
	{ok, << Length1:24, 1:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	{ok, _} = gen_tcp:recv(Socket, Length1, 6000),
	{ok, << Length2:24, 0:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	{ok, _} = gen_tcp:recv(Socket, Length2, 6000),
	%% Send a DATA frame on the now closed stream.
	ok = gen_tcp:send(Socket, cow_http2:data(1, fin, <<"Unexpected DATA frame.">>)),
	%% Receive a STREAM_CLOSED connection error.
	{ok, << _:24, 7:8, _:72, 5:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

stream_closed_reject_headers(Config) ->
	doc("HEADERS frames received on a stream closed normally must be rejected "
		"with a STREAM_CLOSED connection error. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, fin, HeadersBlock)),
	%% Receive the response.
	{ok, << Length1:24, 1:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	{ok, _} = gen_tcp:recv(Socket, Length1, 6000),
	{ok, << Length2:24, 0:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	{ok, _} = gen_tcp:recv(Socket, Length2, 6000),
	%% Send a HEADERS frame on the now closed stream.
	ok = gen_tcp:send(Socket, cow_http2:headers(1, fin, HeadersBlock)),
	%% Receive a STREAM_CLOSED connection error.
	{ok, << _:24, 7:8, _:72, 5:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

stream_closed_accept_priority(Config) ->
	doc("PRIORITY frames received on a stream closed normally must be accepted. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, nofin, HeadersBlock)),
	%% Receive the response.
	{ok, << Length1:24, 1:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	{ok, _} = gen_tcp:recv(Socket, Length1, 6000),
	{ok, << Length2:24, 0:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	{ok, _} = gen_tcp:recv(Socket, Length2, 6000),
	%% Send a PRIORITY frame on the now closed stream.
	ok = gen_tcp:send(Socket, cow_http2:priority(1, shared, 3, 123)),
	%% Receive nothing back.
	{error, timeout} = gen_tcp:recv(Socket, 9, 6000),
	ok.

stream_closed_accept_rst_stream(Config) ->
	doc("RST_STREAM frames received on a stream closed normally "
		"must be accepted for a short period. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, nofin, HeadersBlock)),
	%% Receive the response.
	{ok, << Length1:24, 1:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	{ok, _} = gen_tcp:recv(Socket, Length1, 6000),
	{ok, << Length2:24, 0:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	{ok, _} = gen_tcp:recv(Socket, Length2, 6000),
	%% Send an RST_STREAM frame on the now closed stream.
	ok = gen_tcp:send(Socket, cow_http2:rst_stream(1, cancel)),
	%% Receive nothing back.
	{error, timeout} = gen_tcp:recv(Socket, 9, 6000),
	ok.

%% stream_closed_reject_push_promise
%%
%% We respond to all PUSH_PROMISE frames with a PROTOCOL_ERROR connection error
%% because PUSH is disabled in that direction. We therefore cannot test other
%% error conditions.

stream_closed_accept_window_update(Config) ->
	doc("WINDOW_UPDATE frames received on a stream closed normally "
		"must be accepted for a short period. (RFC7540 5.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, nofin, HeadersBlock)),
	%% Receive the response.
	{ok, << Length1:24, 1:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	{ok, _} = gen_tcp:recv(Socket, Length1, 6000),
	{ok, << Length2:24, 0:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	{ok, _} = gen_tcp:recv(Socket, Length2, 6000),
	%% Send a WINDOW_UPDATE frame on the now closed stream.
	ok = gen_tcp:send(Socket, cow_http2:window_update(1, 12345)),
	%% Receive nothing back.
	{error, timeout} = gen_tcp:recv(Socket, 9, 6000),
	ok.

%% @todo While we accept RST_STREAM and WINDOW_UPDATE for a short period
%% after the stream closed normally, we may want to reject the ones coming
%% a significant amount of time after that.

%% @todo Frames may arrive on a stream after we send an RST_STREAM for it.
%% They must be ignored for a short period of time:
%
%      If this state is reached as a result of sending a RST_STREAM
%      frame, the peer that receives the RST_STREAM might have already
%      sent -- or enqueued for sending -- frames on the stream that
%      cannot be withdrawn.  An endpoint MUST ignore frames that it
%      receives on closed streams after it has sent a RST_STREAM frame.
%      An endpoint MAY choose to limit the period over which it ignores
%      frames and treat frames that arrive after this time as being in
%      error.

%% @todo Ensure that rejected DATA frames result in the connection
%% flow-control window being updated. How to test this?
%
%      Flow-controlled frames (i.e., DATA) received after sending
%      RST_STREAM are counted toward the connection flow-control window.
%      Even though these frames might be ignored, because they are sent
%      before the sender receives the RST_STREAM, the sender will
%      consider the frames to count against the flow-control window.

%% Stream identifiers.

reject_streamid_even(Config) ->
	doc("HEADERS frames received with an even-numbered streamid "
		"must be rejected with a PROTOCOL_ERROR connection error. (RFC7540 5.1.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame with an even-numbered streamid.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(2, fin, HeadersBlock)),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

reject_streamid_0(Config) ->
	doc("HEADERS frames received with streamid 0 (zero) "
		"must be rejected with a PROTOCOL_ERROR connection error. (RFC7540 5.1.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame with an streamid 0.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(0, fin, HeadersBlock)),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

http_upgrade_reject_reuse_streamid_1(Config) ->
	doc("Attempts to reuse streamid 1 after upgrading to HTTP/2 "
		"must be rejected with a PROTOCOL_ERROR connection error. (RFC7540 5.1.1)"),
	{ok, Socket} = gen_tcp:connect("localhost", config(port, Config), [binary, {active, false}]),
	ok = gen_tcp:send(Socket, [
		"GET / HTTP/1.1\r\n"
		"Host: localhost\r\n"
		"Connection: Upgrade, HTTP2-Settings\r\n"
		"Upgrade: h2c\r\n"
		"HTTP2-Settings: ", base64:encode(cow_http2:settings_payload(#{})), "\r\n",
		"\r\n"]),
	ok = do_recv_101(Socket),
	%% Send a valid preface.
	ok = gen_tcp:send(Socket, ["PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", cow_http2:settings(#{})]),
	%% Receive the server preface.
	{ok, << Len:24 >>} = gen_tcp:recv(Socket, 3, 1000),
	{ok, << 4:8, 0:40, _:Len/binary >>} = gen_tcp:recv(Socket, 6 + Len, 1000),
	%% Send the SETTINGS ack.
	ok = gen_tcp:send(Socket, cow_http2:settings_ack()),
	%% Receive the SETTINGS ack, and the response HEADERS and DATA (Stream ID 1).
	Received = lists:reverse(lists:foldl(fun(_, Acc) ->
		case gen_tcp:recv(Socket, 9, 1000) of
			{ok, << 0:24, 4:8, 1:8, 0:32 >>} ->
				[settings_ack|Acc];
			{ok, << SkipLen:24, 1:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[headers|Acc];
			{ok, << SkipLen:24, 0:8, _:8, 1:32 >>} ->
				{ok, _} = gen_tcp:recv(Socket, SkipLen, 1000),
				[data|Acc]
		end
	end, [], [1, 2, 3])),
	case Received of
		[settings_ack, headers, data] -> ok;
		[headers, settings_ack, data] -> ok;
		[headers, data, settings_ack] -> ok
	end,
	%% Send a HEADERS frame with streamid 1.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(1, fin, HeadersBlock)),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

reject_streamid_lower(Config) ->
	doc("HEADERS frames received with streamid lower than the previous stream "
		"must be rejected with a PROTOCOL_ERROR connection error. (RFC7540 5.1.1)"),
	{ok, Socket} = do_handshake(Config),
	%% Send a HEADERS frame with streamid 5.
	{HeadersBlock, _} = cow_hpack:encode([
		{<<":method">>, <<"GET">>},
		{<<":scheme">>, <<"http">>},
		{<<":authority">>, <<"localhost">>}, %% @todo Correct port number.
		{<<":path">>, <<"/">>}
	]),
	ok = gen_tcp:send(Socket, cow_http2:headers(5, fin, HeadersBlock)),
	%% Receive the response.
	{ok, << Length1:24, 1:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	{ok, _} = gen_tcp:recv(Socket, Length1, 6000),
	{ok, << Length2:24, 0:8, _:40 >>} = gen_tcp:recv(Socket, 9, 6000),
	{ok, _} = gen_tcp:recv(Socket, Length2, 6000),
	%% Send a HEADERS frame with streamid 3.
	ok = gen_tcp:send(Socket, cow_http2:headers(3, fin, HeadersBlock)),
	%% Receive a PROTOCOL_ERROR connection error.
	{ok, << _:24, 7:8, _:72, 1:32 >>} = gen_tcp:recv(Socket, 17, 6000),
	ok.

%% @todo We need an option to limit the number of streams one can open
%% on a connection. And we need to enforce it.
%
%   Stream identifiers cannot be reused.  Long-lived connections can
%   result in an endpoint exhausting the available range of stream
%   identifiers.  A server
%   that is unable to establish a new stream identifier can send a GOAWAY
%   frame so that the client is forced to open a new connection for new
%   streams.