Implement function for IPv4-mapped IPv6 addresses

3 files changed, 48 insertions, 5 deletions

diff --git a/lib/kernel/doc/src/inet.xml b/lib/kernel/doc/src/inet.xml
index abb045b744..5c56247820 100644
--- a/lib/kernel/doc/src/inet.xml
+++ b/lib/kernel/doc/src/inet.xml
@@ -4,7 +4,7 @@
 <erlref>
   <header>
     <copyright>
-      <year>1997</year><year>2017</year>
+      <year>1997</year><year>2018</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -582,6 +582,19 @@ get_tcpi_sacked(Sock) ->
     </func>
 
     <func>
+      <name name="ipv4_mapped_ipv6_address" arity="1" />
+      <fsummary>Convert to and from IPv4-mapped IPv6 address.</fsummary>
+      <desc>
+	<p>
+	  Convert an IPv4 address to an IPv4-mapped IPv6 address
+	  or the reverse.  When converting from an IPv6 address
+	  all but the 2 low words are ignored so this function also
+	  works on some other types of addresses than IPv4-mapped.
+	</p>
+      </desc>
+    </func>
+
+    <func>
       <name name="parse_strict_address" arity="1" />
       <fsummary>Parse an IPv4 or IPv6 address strict.</fsummary>
       <desc>
diff --git a/lib/kernel/src/inet.erl b/lib/kernel/src/inet.erl
index fe91b0d33e..fd26a88d42 100644
--- a/lib/kernel/src/inet.erl
+++ b/lib/kernel/src/inet.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1997-2017. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2018. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -34,7 +34,8 @@
 	 ip/1, stats/0, options/0, 
 	 pushf/3, popf/1, close/1, gethostname/0, gethostname/1, 
 	 parse_ipv4_address/1, parse_ipv6_address/1, parse_ipv4strict_address/1,
-	 parse_ipv6strict_address/1, parse_address/1, parse_strict_address/1, ntoa/1]).
+	 parse_ipv6strict_address/1, parse_address/1, parse_strict_address/1,
+         ntoa/1, ipv4_mapped_ipv6_address/1]).
 
 -export([connect_options/2, listen_options/2, udp_options/2, sctp_options/2]).
 -export([udp_module/1, tcp_module/1, tcp_module/2, sctp_module/1]).
@@ -675,6 +676,14 @@ parse_address(Addr) ->
 parse_strict_address(Addr) ->
     inet_parse:strict_address(Addr).
 
+-spec ipv4_mapped_ipv6_address(ip_address()) -> ip_address().
+ipv4_mapped_ipv6_address({D1,D2,D3,D4})
+  when (D1 bor D2 bor D3 bor D4) < 256 ->
+    {0,0,0,0,0,16#ffff,(D1 bsl 8) bor D2,(D3 bsl 8) bor D4};
+ipv4_mapped_ipv6_address({D1,D2,D3,D4,D5,D6,D7,D8})
+  when (D1 bor D2 bor D3 bor D4 bor D5 bor D6 bor D7 bor D8) < 65536 ->
+    {D7 bsr 8,D7 band 255,D8 bsr 8,D8 band 255}.
+
 %% Return a list of available options
 options() ->
     [
diff --git a/lib/kernel/test/inet_SUITE.erl b/lib/kernel/test/inet_SUITE.erl
index 3b502be8b8..77ac743a6e 100644
--- a/lib/kernel/test/inet_SUITE.erl
+++ b/lib/kernel/test/inet_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1997-2017. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2018. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -40,7 +40,8 @@
 	 lookup_bad_search_option/1,
 	 getif/1,
 	 getif_ifr_name_overflow/1,getservbyname_overflow/1, getifaddrs/1,
-	 parse_strict_address/1, simple_netns/1, simple_netns_open/1,
+	 parse_strict_address/1, ipv4_mapped_ipv6_address/1,
+         simple_netns/1, simple_netns_open/1,
          simple_bind_to_device/1, simple_bind_to_device_open/1]).
 
 -export([get_hosts/1, get_ipv6_hosts/1, parse_hosts/1, parse_address/1,
@@ -667,6 +668,26 @@ parse_strict_address(Config) when is_list(Config) ->
     {ok, {3089,3106,23603,50240,0,0,119,136}} =
 	inet:parse_strict_address("c11:0c22:5c33:c440::077:0088").
 
+ipv4_mapped_ipv6_address(Config) when is_list(Config) ->
+    {D1,D2,D3,D4} = IPv4Address =
+        {rand:uniform(256) - 1,
+         rand:uniform(256) - 1,
+         rand:uniform(256) - 1,
+         rand:uniform(256) - 1},
+    E7 = (D1 bsl 8) bor D2,
+    E8 = (D3 bsl 8) bor D4,
+    io:format("IPv4Address: ~p.~n", [IPv4Address]),
+    {0,0,0,0,0,65535,E7,E8} = inet:ipv4_mapped_ipv6_address(IPv4Address),
+    IPv6Address =
+        {rand:uniform(65536) - 1,
+         rand:uniform(65536) - 1,
+         rand:uniform(65536) - 1,
+         rand:uniform(65536) - 1,
+         rand:uniform(65536) - 1,
+         rand:uniform(65536) - 1, E7, E8},
+    IPv4Address = inet:ipv4_mapped_ipv6_address(IPv6Address),
+    ok.
+
 t_gethostnative(Config) when is_list(Config) ->
     %% this will result in 26 bytes sent which causes problem in Windows
     %% if the port-program has not assured stdin to be read in BINARY mode