inets ftp bug

Serge Aleynikov <>
Wed Aug 24 00:43:54 CEST 2005


OTP team:

This is my second attempt to fix the issue with inets' ftp.erl, which 
seems to be more involved than I initially thought.  In this version of 
ftp.erl ftp:recv/2 seems to be working correctly, however, I am not 
quite sure that this fix covered all errors in the implementation (which 
IMHO is quite messy), and would prefer if one of the authors would take 
a look at it.

 > ftp_test:test("localhost", "serge", "...", "/home/serge/tmp/data", 
"dial_code.txt").
"220 ProFTPD 1.2.6 Server (DevLinuxPro FTP) [devlinuxpro.mis.idt.net]"
"331 Password required for serge."
"230 User serge logged in."
"250 CWD command successful."
"500 EPSV not understood."
"200 PORT command successful"
"150 Opening ASCII mode data connection for dial_code.txt (5271838 bytes)"
"226 Transfer complete."
"200 PORT command successful"
"150 Opening ASCII mode data connection for dial_code.txt (5271838 bytes)"
"226 Transfer complete."
ok

Regards,

Serge

Serge Aleynikov wrote:
> Actually, there seems to be one more (at least :-( ) issue with the 
> ftp.erl.  With the applied patch there is no more exception raised, but 
> the second transfer of a file doesn't happen if you run the code outside 
> of the debugger.
> 
> When running with a debugger, I get:
> 
> ~/tmp/dirtest>erl
> Erlang (BEAM) emulator version 5.4.8 [source] [hipe] [threads:0]
> 
> Eshell V5.4.8  (abort with ^G)
> 1> i:ii(ftp).
> {module,ftp}
> 2> i:ib(ftp, activate_data_connection, 1).
> ok
> 3> debugger:start().
> {ok,<0.36.0>}
> 4> ftp_test:test("localhost", "serge", "...", "/home/serge/tmp/data", 
> "cust_group.txt").
> "220 ProFTPD 1.2.6 Server (DevLinuxPro FTP) [devlinuxpro.mis.idt.net]"
> "331 Password required for serge."
> "230 User serge logged in."
> "250 CWD command successful."
> "500 EPSV not understood."
> "200 PORT command successful"
> "150 Opening ASCII mode data connection for cust_group.txt (7487 bytes)"
> "226 Transfer complete."
> "150 Opening ASCII mode data connection for cust_group.txt (7487 bytes)"
> ok
> 
> This is good and expected. We can see that the file is transfered twice.
> Now the same call without debugger:
> 
> ~/tmp/dirtest>erl
> Erlang (BEAM) emulator version 5.4.8 [source] [hipe] [threads:0]
> 
> Eshell V5.4.8  (abort with ^G)
> 1> ftp_test:test("localhost", "serge", "...", "/home/serge/tmp/data", 
> "cust_group.txt").
> "220 ProFTPD 1.2.6 Server (DevLinuxPro FTP) [devlinuxpro.mis.idt.net]"
> "331 Password required for serge."
> "230 User serge logged in."
> "250 CWD command successful."
> "500 EPSV not understood."
> "200 PORT command successful"
> "150 Opening ASCII mode data connection for cust_group.txt (7487 bytes)"
> "226 Transfer complete."
> "200 PORT command successful"
> ok
> 
> No transfer is happening after the successful PORT command...
> 
> Serge
> 
> 
> Serge Aleynikov wrote:
> 
>> OTP team:
>>
>> I found a bug in the inets' ftp.erl client that can be patched by 
>> applying the ftp.erl.patch file to the source.
>>
>> The bug is seen when you try to download more than one file in a row 
>> using ftp:recv/2 function.  For some reason this bug doesn't occur 
>> when tracing is enabled (and/or debugger application is running).
>>
>> Use the following to reproduce the bug:
>>
>> ftp_test:test(Host, User, Password, RemoteDir, RemoteFile).
>>
>> ~/tmp/dirtest>erl -pa ~/Projects/DRP/lib/drpdb-1.0/ebin
>> Erlang (BEAM) emulator version 5.4.8 [source] [hipe] [threads:0]
>>
>> Eshell V5.4.8  (abort with ^G)
>> 1> ftp_test:test("localhost", "serge", "...", "/home/serge", "tt.txt").
>> "220 ProFTPD 1.2.6 Server (DevLinuxPro FTP) [devlinuxpro.mis.idt.net]"
>> "331 Password required for serge."
>> "230 User serge logged in."
>> "250 CWD command successful."
>> "500 EPSV not understood."
>> "200 PORT command successful"
>> "150 Opening ASCII mode data connection for tt.txt (7487 bytes)"
>> "226 Transfer complete."
>> "200 PORT command successful"
>> ** exited: {{function_clause,[{inet,tcp_close,[{lsock,#Port<0.123>}]},
>>                               {ftp,do_termiante,2},
>>                               {gen_server,terminate,6},
>>                               {proc_lib,init_p,5}]},
>>             {gen_server,call,
>>                         [<0.42.0>,
>>                          {recv,"tt.txt","tt.txt"},
>>                          infinity]}} **
>>
>> Hope that it can make it in the next OTP release.
>>
>> Regards,
>>
>> Serge
>>
>>
>> ------------------------------------------------------------------------
>>
>> -module(ftp_test).
>>
>> -export([test/5]).
>>
>> test(Host, User, Password, Dir, File) ->
>>     application:start(inets),
>>     {ok, Pid} = ftp:open(Host, [verbose]),
>>     ok = ftp:user(Pid, User, Password),
>>     ok = ftp:cd(Pid, Dir),
>>     ok = ftp:recv(Pid, File),
>>     ok = ftp:recv(Pid, File),
>>     ftp:close(Pid).
>>
>>
>> ------------------------------------------------------------------------
>>
>> --- /usr/local/lib/erlang/lib/inets-4.5/src/ftp.erl    Tue Aug 23 
>> 13:28:08 2005
>> +++ ftp.erl    Tue Aug 23 16:39:43 2005
>> @@ -790,11 +790,11 @@
>>  %% terminate/2 and code_change/3
>>  %%-------------------------------------------------------------------------- 
>>
>>  terminate(normal, State) ->
>> -    do_termiante({error, econn}, State);
>> +    do_terminate({error, econn}, State);
>>  terminate(Reason, State) ->
>> -    do_termiante({error, Reason}, State).
>> +    do_terminate({error, Reason}, State).
>>  
>> -do_termiante(ErrorMsg, State) ->
>> +do_terminate(ErrorMsg, State) ->
>>      close_data_connection(State),
>>      close_ctrl_connection(State),
>>      case State#state.client of
>> @@ -1313,6 +1313,8 @@
>>  
>>  close_data_connection(#state{dsock = undefined}) ->
>>      ok;
>> +close_data_connection(#state{dsock = {lsock, Socket}}) ->
>> +    close_connection(Socket);
>>  close_data_connection(#state{dsock = Socket}) ->
>>      close_connection(Socket).
> 
> 

-- 
Serge Aleynikov
R&D Telecom, IDT Corp.
Tel: (973) 438-3436
Fax: (973) 438-1464

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