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;"><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;"><?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;"><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;"><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;"><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;"><?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;"><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;">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;">...... 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;"><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;"><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;"> case Type of      </span><span 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。