问题描述
我在ejabberd中添加了一个名为 mod_confirm_delivery 的自定义模块，该模块已成功编译并添加，但是当我发送消息时，我的ejabberd错误日志文件中出现错误，也就是说：
I have added a customized module named mod_confirm_delivery in ejabberd which has compiled and added successfully but when i am sending a message an error is coming in my ejabberd error log file, That is:
2016-03-15 17:03:38.306 [error] <0.2653.0>@ejabberd_hooks:run_fold1:368 {undef,[{mod_confirm_delivery,send_packet,[{xmlel,<<"iq">>,[{<<"xml:lang">>,<<"en">>},{<<"type">>,<<"get">>},{<<"id">>,<<"aacfa">>}],[{xmlcdata,<<"\n">>},{xmlel,<<"query">>,[{<<"xmlns">>,<<"jabber:iq:roster">>}],[]},{xmlcdata,<<"\n">>}]},{state,{socket_state,gen_tcp,#Port<0.58993>,<0.2652.0>},ejabberd_socket,#Ref<0.0.1.25301>,false,<<"12664578908237388886">>,undefined,c2s,c2s_shaper,false,false,false,false,[verify_none,compression_none],true,{jid,<<"test1">>,<<"localhost">>,<<"D-5">>,<<"test1">>,<<"localhost">>,<<"D-5">>},<<"test1">>,<<"localhost">>,<<"D-5">>,{{1458,41617,630679},<0.2653.0>},{2,{{<<"test2">>,<<"localhost">>,<<>>},{{<<"test1">>,<<"localhost">>,<<>>},nil,nil},nil}},{2,{{<<"test2">>,<<"localhost">>,<<>>},{{<<"test1">>,<<"localhost">>,<<>>},nil,nil},nil}},{0,nil},undefined,undefined,{userlist,none,[],false},c2s,ejabberd_auth_internal,{{127,0,0,1},41928},[],active,[],inactive,undefined,undefined,1000,undefined,300,300,false,0,0,true,<<"en">>},{jid,<<"test1">>,<<"localhost">>,<<"D-5">>,<<"test1">>,<<"localhost">>,<<"D-5">>},{jid,<<"test1">>,<<"localhost">>,<<>>,<<"test1">>,<<"localhost">>,<<>>}],[]},{ejabberd_hooks,safe_apply,3,[{file,"src/ejabberd_hooks.erl"},{line,382}]},{ejabberd_hooks,run_fold1,4,[{file,"src/ejabberd_hooks.erl"},{line,365}]},{ejabberd_c2s,session_established2,2,[{file,"src/ejabberd_c2s.erl"},{line,1268}]},{p1_fsm,handle_msg,10,[{file,"src/p1_fsm.erl"},{line,582}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,240}]}]}
我有ejabberd 16.02.26和我的模块代码为：
I have ejabberd 16.02.26 and my module code is:mod_confirm_delivery.erl
该模块在ejabberd 2.1.13上运行良好，但是我想升级ejabberd。我不明白是什么问题，以及如何解决此错误。
This module is working fine with ejabberd 2.1.13 but i want to upgraded my ejabberd. I can't understand what is the problem and how can I resolve this error.
推荐答案
undef错误表示未找到功能或模块。最可能的错误是 mod_confirm_delivery.beam 文件不在Erlang VM路径中。
undef error means the function or module is not found. The most likely error is that the mod_confirm_delivery.beam file is not in Erlang VM path.
您应该尝试移动编译后的梁文件以及其他ejabberd梁文件，或尝试将用于启动Erlang的路径设置为 mod_confirm_delivery.beam 文件所在的目录。这是Erlang VM的-pa选项。
You should try moving the compiled beam file with other ejabberd beam files or try setting the path used to launch Erlang to the directory where your mod_confirm_delivery.beam file is located. This is the -pa option of the Erlang VM.
如果您的代码在正确的位置，则另一个选项是函数未定义。挂钩尝试调用 mod_confirm_delivery：send_packet / 4 。您的代码是错误的，因为它确实未定义 send_packet / 4 ，而仅定义了 send_packet / 3 。您需要更新代码以匹配 user_send_packet 钩子的新签名：
If your code if in right place, other option is that the function is undefined. The hook tries to call mod_confirm_delivery:send_packet/4. Your code is wrong as it indeed does not defined send_packet/4 but only send_packet/3. You need to update your code to match new signature for user_send_packet hook:
user_send_packet(Packet, C2SState, From, To) -> Packet
如有疑问，您可以参考ejabberd文档中的官方挂钩列表：
In case of doubt, you can refer to official hook list in ejabberd documentation: https://docs.ejabberd.im/developer/hooks/
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