ejabberd分析(二) 用户注册

 

ejabberd中由ejabberd_c2s处理：

ejabberd_c2s模块启动后gen_fsm的状态位于wait_for_stream

客户端发送

<span style="color: #FF0000;" mce_style="color: #FF0000;"><stream:stream to="localhost" xmlns="jabber:client" xmlns:stream="http://etherx.jabber.org/streams" version="1.0"></span>

服务器端wait_for_stream 函数中经过

 

 

   case xml:get_attr_s("xmlns:stream", Attrs) of
	?NS_STREAM ->
            ......
                case xml:get_attr_s("version", Attrs) of
             "1.0" ->
                send_header(StateData, Server, "1.0", DefaultLang),

发送如下的响应给客户端

 

 

<span style="color: #FF0000;" mce_style="color: #FF0000;"><?xml version='1.0' encoding='UTF-8'?><stream:stream xmlns:stream="http://etherx.jabber.org/streams" xmlns="jabber:client" from="kinglong" id="fecabb98" xml:lang="en" version="1.0"></span>

由于客户端在注册时并未通过鉴权，所以wait_for_stream 中经过如下路径

 

 

case StateData#state.authenticated of
		false ->
           ......
            send_element(StateData,
       {xmlelement, "stream:features", [],
       TLSFeature ++ CompressFeature ++
       [{xmlelement, "mechanisms",
       [{"xmlns", ?NS_SASL}],
       Mechs}] ++
       ejabberd_hooks:run_fold(
       c2s_stream_features,
       Server,
       [], [Server])}),
           fsm_next_state(wait_for_feature_request,
      StateData#state{
       server = Server,
       sasl_state = SASLState,
       lang = Lang});

向客户端发送feature消息，并将当前状态设置为wait_for_feature_request

 

 

<span style="color: #FF0000;" mce_style="color: #FF0000;"><stream:features><starttls xmlns="urn:ietf:params:xml:ns:xmpp-tls"></starttls><mechanisms xmlns="urn:ietf:params:xml:ns:xmpp-sasl"><mechanism>DIGEST-MD5</mechanism><mechanism>JIVE-SHAREDSECRET</mechanism><mechanism>PLAIN</mechanism><mechanism>ANONYMOUS</mechanism><mechanism>CRAM-MD5</mechanism></mechanisms><compression xmlns="http://jabber.org/features/compress"><method>zlib</method></compression><auth xmlns="http://jabber.org/features/iq-auth"/><register xmlns="http://jabber.org/features/iq-register"/></stream:features></span>

 

客户端发送给服务器端

<span style="color: #FF0000;" mce_style="color: #FF0000;"><starttls xmlns="urn:ietf:params:xml:ns:xmpp-tls"/></span>

 

服务器端函数wait_for_feature_request中经过如下路径，并将状态再次设置为wait_for_stream：

 

{?NS_TLS, "starttls"} when TLS == true,
				   TLSEnabled == false,
				   SockMod == gen_tcp ->

客户端发送给服务器端

 

 

<span style="color: #FF0000;" mce_style="color: #FF0000;"><stream:stream to="kinglong" xmlns="jabber:client" xmlns:stream="http://etherx.jabber.org/streams" version="1.0"></span>

服务器端wait_for_stream中仍然经由以下路径：

 

 

case xml:get_attr_s("xmlns:stream", Attrs) of
	?NS_STREAM ->
        ......
            case xml:get_attr_s("version", Attrs) of
   "1.0" ->
               ......
               case StateData#state.authenticated of
    false ->
                   ......
                   send_element(StateData,
       {xmlelement, "stream:features", [],
       TLSFeature ++ CompressFeature ++
       [{xmlelement, "mechanisms",
       [{"xmlns", ?NS_SASL}],
       Mechs}] ++
       ejabberd_hooks:run_fold(
       c2s_stream_features,
       Server,
       [], [Server])}),

send_element函数发送如下消息给客户端，展示服务器端可提供的鉴权方法，并再次将状态设置为wait_for_feature_request

 

 

<span style="color: #FF0000;" mce_style="color: #FF0000;"><?xml version='1.0' encoding='UTF-8'?>
 <stream:stream xmlns:stream="http://etherx.jabber.org/streams" xmlns="jabber:client" from="kinglong" id="fecabb98" xml:lang="en" version="1.0">
   <stream:features>
     <mechanisms xmlns="urn:ietf:params:xml:ns:xmpp-sasl">
        <mechanism>DIGEST-MD5</mechanism>
        <mechanism>JIVE-SHAREDSECRET</mechanism>
        <mechanism>PLAIN</mechanism>
        <mechanism>ANONYMOUS</mechanism>
        <mechanism>CRAM-MD5</mechanism>
     </mechanisms>
     <compression xmlns="http://jabber.org/features/compress">
        <method>zlib</method>
     </compression>
     <auth xmlns="http://jabber.org/features/iq-auth"/>
     <register xmlns="http://jabber.org/features/iq-register"/>
   </stream:features></span>

 

由于是注册过程，所以客户端并不会从中挑一种开始鉴权过程，而是发送如下的iq消息给服务器端。以下消息查询服务器端注册时所需要的参数

 

<span style="color: #FF0000;" mce_style="color: #FF0000;"><iq id="2hSnG-4" to="kinglong" type="get"><query xmlns="jabber:iq:register"></query></iq></span>

服务器端的wait_for_feature_request 函数中按照xmlns属性处理：

 

 

case {xml:get_attr_s("xmlns", Attrs), Name} of
    {?NS_SASL, "auth"} when not ((SockMod == gen_tcp) and TLSRequired) ->
         ......
    {?NS_TLS, "starttls"} when TLS == true,
     TLSEnabled == false,
     SockMod == gen_tcp ->
         ......
    {?NS_COMPRESS, "compress"} when Zlib == true,
     ((SockMod == gen_tcp) or
      (SockMod == tls)) ->
         ......
    _ ->
         .......
         process_unauthenticated_stanza(StateData, El),

由于客户端发送的是iq消息，xmlns会匹配到最后一项。

 

在process_unauthenticated_stanza函数中：

 

case jlib:iq_query_info(NewEl) of
	#iq{} = IQ ->
        Res = ejabberd_hooks:run_fold(c2s_unauthenticated_iq,
      StateData#state.server,
      empty,
      [StateData#state.server, IQ,
      StateData#state.ip]),

调用含有名为c2s_unauathenticated_iq回调函数的模块来处理iq消息。

 

此回调函数在mod_register模块中定义：

 

start(Host, Opts) ->
    ......
    ejabberd_hooks:add(c2s_unauthenticated_iq, Host,
 		       ?MODULE, unauthenticated_iq_register, 50),
    ......

其对应于mod_register模块中的unathenticated_iq_register方法

unauthenticated_iq_register(_Acc,
			    Server, #iq{xmlns = ?NS_REGISTER} = IQ, IP) ->
    Address = case IP of
		 {A, _Port} -> A;
		  _ -> undefined
	      end,
    <span style="color: #000099;" mce_style="color: #000099;">ResIQ = process_iq(jlib:make_jid("", "", ""),
 		       jlib:make_jid("", Server, ""),
 		       IQ,
		       Address),</span>
    Res1 = jlib:replace_from_to(jlib:make_jid("", Server, ""),
 				jlib:make_jid("", "", ""),
 				jlib:iq_to_xml(ResIQ)),
    jlib:remove_attr("to", Res1);

以上标蓝的部分即为具体的处理函数。process_iq 将iq按照type 分为两类来处理：

 

 

process_iq(From, To,
	   #iq{type = Type, lang = Lang, sub_el = SubEl, id = ID} = IQ,
	   Source) ->
           ......
           case Type of
              set ->
           <span style="color: #000099;" mce_style="color: #000099;">......
                 get -></span>
             

 

本次客户端发送的iq type 为get ，所以匹配到get

至于下面的判断我们目前可以直接无视，匹配到true就OK。

if IsCaptchaEnabled and not IsRegistered ->
   .....
   true ->
   IQ#iq{type = result,
    sub_el = [{xmlelement,
     "query",
     [{"xmlns", "jabber:iq:register"}],
     [{xmlelement, "instructions", [],
     [{xmlcdata,
      translate:translate(
      Lang,
      "Choose a username and password "
      "to register with this server")}]},
     {xmlelement, "username", [], UsernameSubels},
     {xmlelement, "password", [], []}
     | QuerySubels]}]}

于是服务器端发送类似如下的响应给客户端：

 

 

<span style="color: #FF0000;" mce_style="color: #FF0000;"><iq type="result" id="2hSnG-4" from="kinglong">
<query xmlns="jabber:iq:register">
<username/><password/>
<email/><name/>
<x xmlns="jabber:x:data" type="form">
<title>XMPP Client Registration</title>
<instructions>Choose a username and password to register with this server</instructions>
<field var="FORM_TYPE" type="hidden">
<value>jabber:iq:register</value>
</field>
<field var="username" type="text-single" label="Username">
<required/>
</field>
<field var="name" type="text-single" label="Full name"/>
<field var="email" type="text-single" label="Email"/>
<field var="password" type="text-private" label="Password">
<required/>
</field>
</x>
</query>
</iq></span>

注意，我们在函数process_unauthenticated_stanza处理完当前的iq后状态仍然设置为了wait_for_feature_request。

 

客户端按照服务器要求的参数发送注册信息给服务器：

 

<span style="color: #FF0000;" mce_style="color: #FF0000;"><iq id="2hSnG-5" to="kinglong" type="set"><query xmlns="jabber:iq:register"><username>15555215557</username><email></email><name></name><password>123</password></query></iq></span>

由于我们的状态没变，消息同样也是iq消息，type=set 所以本次轮到了set的处理：

 

 

process_iq(From, To,
	   #iq{type = Type, lang = Lang, sub_el = SubEl, id = ID} = IQ,
	   Source) ->
           ......
          <span style="color: #3333FF;" mce_style="color: #3333FF;"> case Type of
              </span><span style="color: #3333FF;" mce_style="color: #3333FF;">set -></span>
           ......
                 get ->

set 项是一个if 结构的语句：

 

 

if (UTag /= false) and (RTag /= false) and AllowRemove ->
       ......
   (UTag == false) and (RTag /= false) and AllowRemove ->
       ......
   (UTag /= false) and (PTag /= false) ->
      .......
   IsCaptchaEnabled ->
      .......
   true ->
   IQ#iq{type = error,
    sub_el = [SubEl, ?ERR_BAD_REQUEST]}

UTag、PTag、RTag 分别对应于username,password,remove

 

正常的注册流程走

(UTag == false) and (RTag /= false) and AllowRemove ->
 ......
try_register_or_set_password( User, Server, Password, From, IQ, SubEl, Source, Lang, not IsCaptchaEnabled)

这里有一个比较关键的变量IsCaptchaEnabled 他是模块的配置参数之一，默认为false。

所以我们在调用try_register_or_set_password 时会匹配到如下代码：

_ when CaptchaSucceed ->

具体注册由try_register 函数完成。

经过ip验证后 调用ejabberd_auth:try_register(
User, Server, Password)

ejabberd_auth中遍历配置文件中的每个MOD，并调用try_register/3 方法。注意：这里配置文件中写的只是模块名称的一部分，完整的为:ejabberd_auth_XXXX

例如ejabberd.cfg 中配置为{auth_method, internal}.那么实际调用的为ejabberd_auth_internal:try_register/3

最终我们在try_register/3 中看到如下的代码：

F = fun() ->
			case mnesia:read({passwd, US}) of
			    [] ->
				Password2 = case is_scrammed() and is_list(Password) of
						true -> password_to_scram(Password);
						false -> Password
					    end,
				mnesia:write(#passwd{us = US,
						     password = Password2}),
				mnesia:dirty_update_counter(
						    reg_users_counter,
						    LServer, 1),
				ok;
			    [_E] ->
				exists
			end
		end,
	    mnesia:transaction(F)

这就是最终注册的代码了。