Accept IPv6 address %suffixes when parsing

This only implements decimal suffixes, and furthermore only with
a leading "0".  A complete implementation would probably allow one
and probably two digit suffixes without.

But what primarily is missing is translating interface names to
and from interface indexes.

This also only implements the parsing, and uses the FreeBSD trick of
squeezing in the Scope Id in the second 16-bit word of the fe80::/64
or ff02:/64 address prefix.  But inet_drv is not prepared to handle
this word, so it might only work on FreeBSD, not being supported even
there...  So inet_drv needs to handle this too.

2 files changed, 77 insertions, 7 deletions

diff --git a/lib/kernel/src/inet_parse.erl b/lib/kernel/src/inet_parse.erl
index 06e1048afe..29804dc50b 100644
--- a/lib/kernel/src/inet_parse.erl
+++ b/lib/kernel/src/inet_parse.erl
@@ -644,8 +644,12 @@ ipv6_addr(Cs) ->
     ipv6_addr(hex(Cs), [], 0).
 
 %% Before "::"
+ipv6_addr({Cs0,"%"++Cs1}, A, N) when N == 7 ->
+    ipv6_addr_scope(Cs1, [hex_to_int(Cs0)|A], [], N+1, []);
 ipv6_addr({Cs0,[]}, A, N) when N == 7 ->
     ipv6_addr_done([hex_to_int(Cs0)|A]);
+ipv6_addr({Cs0,"::%"++Cs1}, A, N) when N =< 6 ->
+    ipv6_addr_scope(Cs1, [hex_to_int(Cs0)|A], [], N+1, []);
 ipv6_addr({Cs0,"::"}, A, N) when N =< 6 ->
     ipv6_addr_done([hex_to_int(Cs0)|A], [], N+1);
 ipv6_addr({Cs0,"::"++Cs1}, A, N) when N =< 5 ->
@@ -658,6 +662,8 @@ ipv6_addr(_, _, _) ->
     erlang:error(badarg).
 
 %% After "::"
+ipv6_addr({Cs0,"%"++Cs1}, A, B, N) when N =< 6 ->
+    ipv6_addr_scope(Cs1, A, [hex_to_int(Cs0)|B], N+1, []);
 ipv6_addr({Cs0,[]}, A, B, N) when N =< 6 ->
     ipv6_addr_done(A, [hex_to_int(Cs0)|B], N+1);
 ipv6_addr({Cs0,":"++Cs1}, A, B, N) when N =< 5 ->
@@ -667,6 +673,43 @@ ipv6_addr({Cs0,"."++_=Cs1}, A, B, N) when N =< 5 ->
 ipv6_addr(_, _, _, _) ->
     erlang:error(badarg).
 
+%% After "%"
+ipv6_addr_scope([], Ar, Br, N, Sr) ->
+    ScopeId =
+        case lists:reverse(Sr) of
+            %% Empty scope id
+            "" -> 0;
+            %% Scope id starts with 0
+            "0"++S -> dec16(S);
+            _ -> 0
+        end,
+    %% Suggested formats for scope id parsing:
+    %%   "" -> "0"
+    %%   "0" -> Scope id 0
+    %%   "1" - "9", "10" - "99" -> "0"++S
+    %%   "0"++DecimalScopeId -> decimal scope id
+    %%   "25"++PercentEncoded -> Percent encoded interface name
+    %%   S -> Interface name (Unicode?)
+    %% Missing: translation from interface name into integer scope id.
+    %% XXX: scope id is actually 32 bit, but we only have room for
+    %% 16 bit in the second address word - ignore or fix (how)?
+    ipv6_addr_scope(ScopeId, Ar, Br, N);
+ipv6_addr_scope([C|Cs], Ar, Br, N, Sr) ->
+    ipv6_addr_scope(Cs, Ar, Br, N, [C|Sr]).
+%%
+ipv6_addr_scope(ScopeId, [P], Br, N)
+  when N =< 7, P =:= 16#fe80;
+       N =< 7, P =:= 16#ff02 ->
+    %% Optimized special case
+    ipv6_addr_done([ScopeId,P], Br, N+1);
+ipv6_addr_scope(ScopeId, Ar, Br, N) ->
+    case lists:reverse(Br++dup(8-N, 0, Ar)) of
+        [P,0|Xs] when P =:= 16#fe80; P =:= 16#ff02 ->
+            list_to_tuple([P,ScopeId|Xs]);
+        _ ->
+            erlang:error(badarg)
+    end.
+
 ipv6_addr_done(Ar, Br, N, {D1,D2,D3,D4}) ->
     ipv6_addr_done(Ar, [((D3 bsl 8) bor D4),((D1 bsl 8) bor D2)|Br], N+2).
 
@@ -690,6 +733,19 @@ hex(Cs, [_|_]=R, _) when is_list(Cs) ->
 hex(_, _, _) ->
     erlang:error(badarg).
 
+%% Parse a reverse decimal integer string, empty is 0
+dec16(Cs) -> dec16(Cs, 0).
+%%
+dec16([], I) -> I;
+dec16([C|Cs], I) when C >= $0, C =< $9 ->
+    case 10*I + (C - $0) of
+        J when 16#ffff < J ->
+            erlang:error(badarg);
+        J ->
+            dec16(Cs, J)
+    end;
+dec16(_, _) -> erlang:error(badarg).
+
 %% Hex string to integer
 hex_to_int(Cs) -> erlang:list_to_integer(Cs, 16).
 
@@ -703,7 +759,7 @@ dup(N, E, L) when is_integer(N), N >= 1 ->
 
 %% Convert IPv4 address to ascii
 %% Convert IPv6 / IPV4 address to ascii (plain format)
-ntoa({A,B,C,D}) ->
+ntoa({A,B,C,D}) when (A band B band C band D band (bnot 16#ff)) =:= 0 ->
     integer_to_list(A) ++ "." ++ integer_to_list(B) ++ "." ++ 
 	integer_to_list(C) ++ "." ++ integer_to_list(D);
 %% ANY
@@ -711,13 +767,25 @@ ntoa({0,0,0,0,0,0,0,0}) -> "::";
 %% LOOPBACK
 ntoa({0,0,0,0,0,0,0,1}) -> "::1";
 %% IPV4 ipv6 host address
-ntoa({0,0,0,0,0,0,A,B}) -> "::" ++ dig_to_dec(A) ++ "." ++ dig_to_dec(B);
+ntoa({0,0,0,0,0,0,A,B}) when (A band B band (bnot 16#ffff)) =:= 0 ->
+    "::" ++ dig_to_dec(A) ++ "." ++ dig_to_dec(B);
 %% IPV4 non ipv6 host address
-ntoa({0,0,0,0,0,16#ffff,A,B}) -> 
+ntoa({0,0,0,0,0,16#ffff,A,B}) when (A band B band (bnot 16#ffff)) =:= 0 ->
     "::ffff:" ++ dig_to_dec(A) ++ "." ++ dig_to_dec(B);
-ntoa({_,_,_,_,_,_,_,_}=T) ->
-    %% Find longest sequence of zeros, at least 2, to replace with "::"
-    ntoa(tuple_to_list(T), []);
+ntoa({A,B,C,D,E,F,G,H})
+  when (A band B band C band D band E band F band G band H band
+            (bnot 16#ffff)) =:= 0 ->
+    if
+        A =:= 16#fe80, B =/= 0;
+        A =:= 16#ff02, B =/= 0 ->
+            %% Find longest sequence of zeros, at least 2,
+            %% to replace with "::"
+            ntoa([A,0,C,D,E,F,G,H], []) ++ "%0" ++ integer_to_list(B);
+        true ->
+            %% Find longest sequence of zeros, at least 2,
+            %% to replace with "::"
+            ntoa([A,B,C,D,E,F,G,H], [])
+    end;
 ntoa(_) ->
     {error, einval}.
 
diff --git a/lib/kernel/test/inet_SUITE.erl b/lib/kernel/test/inet_SUITE.erl
index bd842da4b3..3b502be8b8 100644
--- a/lib/kernel/test/inet_SUITE.erl
+++ b/lib/kernel/test/inet_SUITE.erl
@@ -544,6 +544,7 @@ parse_address(Config) when is_list(Config) ->
 	 {{16#c11,16#c22,16#5c33,0,0,0,0,0},
 	  "c11:c22:5c33::"},
 	 {{0,0,0,0,0,65535,258,65534},"::ffff:1.2.255.254"},
+         {{16#fe80,12345,0,0,0,0,0,16#12},"fe80::12%012345"},
 	 {{16#ffff,16#ffff,16#ffff,16#ffff,16#ffff,16#ffff,16#ffff,16#ffff},
 	  "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff"}
          |[{list_to_tuple(P++[(D1 bsl 8) bor D2,(D3 bsl 8) bor D4]),
@@ -576,7 +577,8 @@ parse_address(Config) when is_list(Config) ->
 	 {{0,0,0,0},"0.00.0.0"},
 	 {{0,0,0,0},"0.0.000000000000.0"}],
     V6Sloppy =
-        [{{16#a,16#b,16#c,16#0,16#0,16#d,16#e,16#f},"A:B:C::d:e:f"}]
+        [{{16#a,16#b,16#c,16#0,16#0,16#d,16#e,16#f},"A:B:C::d:e:f"},
+         {{16#fe80,0,0,0,0,0,0,16#12},"fe80::12%XXXXXXX"}]
         ++
         [{{P,0,0,0,0,D2,(D1 bsl 8) bor D2,(D3 bsl 8) bor D4},
           Q++erlang:integer_to_list(D2, 16)++":"++S}