Introduce mod_avatar

The purpose of the module is to cope with legacy and modern
XMPP clients posting avatars. It automatically converts vCard based
avatars (XEP-0153) to PEP based avatars (XEP-0084) and vice versa.
Also, the module supports convertation between avatar image formats on
the fly: this is controlled by `convert` option. For example, to
convert all avatars into PNG format, configure the module as:

mod_avatar:
  convert:
    default: png

In order to convert only `webp` format to `jpeg`, set the following:

mod_avatar:
  convert:
    webp: jpeg

Note: the module depends on mod_vcard, mod_vcard_xupdate and mod_pubsub.
Also, ejabberd should be built with --enable-graphics option.

configure.ac

@@ -236,6 +236,14 @@ AC_ARG_ENABLE(sip,
   *) AC_MSG_ERROR(bad value ${enableval} for --enable-sip) ;;
 esac],[if test "x$sip" = "x"; then sip=false; fi])
 
+AC_ARG_ENABLE(graphics,
+[AC_HELP_STRING([--enable-graphics], [enable support for graphic images manipulation (default: yes)])],
+[case "${enableval}" in
+  yes) graphics=true ;;
+  no)  graphics=false ;;
+  *) AC_MSG_ERROR(bad value ${enableval} for --enable-graphics) ;;
+esac],[if test "x$graphics" = "x"; then graphics=true; fi])
+
 AC_CONFIG_FILES([Makefile
 		 vars.config
 		 src/ejabberd.app.src])
@@ -280,6 +288,7 @@ AC_SUBST(iconv)
 AC_SUBST(stun)
 AC_SUBST(sip)
 AC_SUBST(debug)
+AC_SUBST(graphics)
 AC_SUBST(tools)
 AC_SUBST(latest_deps)
 AC_SUBST(system_deps)

rebar.config

@@ -25,7 +25,7 @@
         {fast_tls, ".*", {git, "https://github.com/processone/fast_tls", {tag, "1.0.15"}}},
         {stringprep, ".*", {git, "https://github.com/processone/stringprep", {tag, "1.0.9"}}},
         {fast_xml, ".*", {git, "https://github.com/processone/fast_xml", {tag, "1.1.23"}}},
-        {xmpp, ".*", {git, "https://github.com/processone/xmpp", {tag, "1.1.14"}}},
+        {xmpp, ".*", {git, "https://github.com/processone/xmpp", "d98be4a3159"}},
         {fast_yaml, ".*", {git, "https://github.com/processone/fast_yaml", {tag, "1.0.10"}}},
         {jiffy, ".*", {git, "https://github.com/davisp/jiffy", {tag, "0.14.8"}}},
         {p1_oauth2, ".*", {git, "https://github.com/processone/p1_oauth2", {tag, "0.6.2"}}},
@@ -44,6 +44,7 @@
                                            {tag, "1.0.2"}}}},
         {if_var_true, riak, {riakc, ".*", {git, "https://github.com/processone/riak-erlang-client.git",
                                            {tag, "2.5.3"}}}},
+	{if_var_true, graphics, {eimp, ".*", {git, "https://github.com/processone/eimp.git"}}},
 	%% Elixir support, needed to run tests
         {if_var_true, elixir, {elixir, ".*", {git, "https://github.com/elixir-lang/elixir",
                                               {tag, {if_version_above, "17", "v1.4.4", "v1.1.1"}}}}},
@@ -74,6 +75,7 @@
                   p1_oauth2,
                   epam,
                   ezlib,
+		  eimp,
                   iconv]}}.
 
 {erl_first_files, ["src/ejabberd_config.erl", "src/gen_mod.erl", "src/mod_muc_room.erl", "src/mod_push.erl"]}.
@@ -87,6 +89,7 @@
             {if_var_true, debug, debug_info},
 	    {if_var_true, sip, {d, 'SIP'}},
 	    {if_var_true, stun, {d, 'STUN'}},
+	    {if_var_true, graphics, {d, 'GRAPHICS'}},
             {if_var_true, roster_gateway_workaround, {d, 'ROSTER_GATWAY_WORKAROUND'}},
             {if_var_match, db_type, mssql, {d, 'mssql'}},
             {if_var_true, elixir, {d, 'ELIXIR_ENABLED'}},
@@ -154,6 +157,7 @@
                        {"fast_xml", [{if_var_true, full_xml, "--enable-full-xml"}]},
                        {if_var_true, pam, {"epam", []}},
                        {if_var_true, zlib, {"ezlib", []}},
+		       {if_var_true, graphics, {"eimp", []}},
                        {if_var_true, iconv, {"iconv", []}}]}.
 
 {port_env, [{"CFLAGS", "-g -O2 -Wall"}]}.

src/ejabberd_app.erl

@@ -146,7 +146,8 @@ start_apps() ->
     ejabberd:start_app(fast_yaml),
     ejabberd:start_app(fast_tls),
     ejabberd:start_app(xmpp),
-    ejabberd:start_app(cache_tab).
+    ejabberd:start_app(cache_tab),
+    start_eimp().
 
 setup_if_elixir_conf_used() ->
   case ejabberd_config:is_using_elixir_config() of
@@ -170,3 +171,11 @@ start_elixir_application() ->
 	_ ->
 	    ok
     end.
+
+-ifdef(GRAPHICS).
+start_eimp() ->
+    ejabberd:start_app(eimp).
+-else.
+start_eimp() ->
+    ok.
+-endif.