Re: Dict proxy client returning empty string instead of multiline string

Hello,

I can confirm the issue is fixed. Do you have a policy to backport the patch at least to the latest stable?

Regards,

On 10/17/2016 11:45 PM, Aki Tuomi wrote:

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>>> On 10/16/2016 11:16 PM, Pierre Jaury wrote: >>>> Hello, >>>> >>>> I am using a dict proxy for my sieve extdata plugin to access some >>>> fields from an SQLite database (autoreply text and other >>>> database-configured items). >>>> >>>> All tests are performed against version 2.2.25. >>>> >>>> $ dovecot --version >>>> 2.2.25 (7be1766) >>>> >>>> My configuration looks like: >>>> >>>> dict { >>>> sieve = sqlite:/etc/dovecot/pigeonhole-sieve.dict >>>> } >>>> >>>> [...] >>>> sieve_extdata_dict_uri = proxy::sieve >>>> >>>> I am able to read pretty much any attribute without any issue, except >>>> when the value contains a special character like "\r" or "\n". By using >>>> the doveadm dict client, I narrowed it down to the dictionary management >>>> part (either server, protocol or client). >>>> >>>> I was suspecting escaping functions from "lib/strescape.c" (mostly >>>> str_tabescape and its counterpart, used by "lib-dict/client.c"), so I >>>> monitored socket communications. It seems that escaping is done properly >>>> on the server and the socket is not an issue either. >>>> >>>> The following strace dump results from running "doveadm dict get" >>>> against the dict socket: >>>> >>>> connect(8, {sa_family=AF_UNIX, sun_path="..."}, 110) = 0 >>>> fstat(8, {st_mode=S_IFSOCK|0777, st_size=0, ...}) = 0 >>>> [...] >>>> write(8, "H2\t0\t0\tadmin@domain.tld\tsieve\n", 30) = 30 >>>> [...] >>>> read(8, "Otest\1r\1ntest\n", 8192) = 14 >>>> >>>> Indeed "\1r" and "\1n" are the escape sequences used by >>>> "lib/strescape.c". I went deeped and debugged the call to "dict_lookup" >>>> performed by doveadm. Indeed the client gets the proper string from the >>>> socket and to my surprise, it is properly unescaped. >>>> >>>> Then, in "client_dict_lookup" ("lib-dict/dict-client.c"), the call to >>>> "p_strdup" returns an empty string (null byte set at the target address). >>>> >>>> Before the call to the dict "->lookup" attribute (client_dict_lookup): >>>> >>>> RAX: 0x7ffff73a37c0 (push r14) >>>> RBX: 0x6831b8 ("priv/reply_body") >>>> RCX: 0x7fffffffe240 --> 0x682a60 --> 0x6831b8 ("priv/reply_body") >>>> RDX: 0x6831b8 ("priv/reply_body") >>>> RSI: 0x683288 --> 0x7ffff7653120 --> 0x7ffff73ea620 ([...]) >>>> RDI: 0x690ad0 --> 0x7ffff7400713 --> 0x75250079786f7270 ('proxy') >>>> >>>> 0x7ffff73a1f10 : mov rcx,r11 (value_r) >>>> 0x7ffff73a1f13 : mov rdx,r8 (key) >>>> 0x7ffff73a1f16 : mov rsi,r10 (pool) >>>> 0x7ffff73a1f19 : mov rdi,r9 (dict) >>>> 0x7ffff73a1f1c : add rsp,0x8 >>>> => 0x7ffff73a1f20 : jmp rax >>>> >>>> Before the call to p_strdup in "client_dict_lookup": >>>> >>>> RSI: 0x6832d8 ("test\r\ntest") (lookup.result.value) >>>> RDI: 0x683288 --> 0x7ffff7653120 --> [...] (pool) >>>> RAX: 0x0 (result) >>>> >>>> 0x7ffff73a384f: nop >>>> 0x7ffff73a3850: mov rsi,QWORD PTR [rsp+0x8] >>>> 0x7ffff73a3855: mov rdi,r14 >>>> => 0x7ffff73a3858: call 0x7ffff736d3c0 p_strdup@plt >>>> 0x7ffff73a385d: mov QWORD PTR [r13+0x0],rax >>>> 0x7ffff73a3861: mov rsi,QWORD PTR [rsp+0x18] >>>> 0x7ffff73a3866: xor rsi,QWORD PTR fs:0x28 >>>> 0x7ffff73a386f: mov eax,ebx >>>> >>>> After the call: >>>> >>>> 0x7ffff73a3850: mov rsi,QWORD PTR [rsp+0x8] >>>> 0x7ffff73a3855: mov rdi,r14 >>>> 0x7ffff73a3858: call 0x7ffff736d3c0 p_strdup@plt >>>> => 0x7ffff73a385d: mov QWORD PTR [r13+0x0],rax >>>> 0x7ffff73a3861: mov rsi,QWORD PTR [rsp+0x18] >>>> 0x7ffff73a3866: xor rsi,QWORD PTR fs:0x28 >>>> 0x7ffff73a386f: mov eax,ebx >>>> 0x7ffff73a3871: jne 0x7ffff73a38da >>>> >>>> RSI: 0x0 >>>> RDI: 0x6832d8 --> 0x0 >>>> RAX: 0x6832d8 --> 0x0 (result) >>>> >>>> It is worth noting that I can reproduce the exact same execution flow >>>> with a non-multiline result string (lookup.result.value) that is >>>> properly copied by "p_strdup" and returned in RAX, then displayed by >>>> doveadm. >>>> >>>> I am not familiar with the pooling mechanism hidden behind the call to >>>> p_strdump and not quite sure why this behaviour is emerging. Maybe I am >>>> even miles away from an understanding of the issue here, but it sounds >>>> to me like something is wrong in the way "p_strdup" performs the copy. >>>> >>>> Hope this helps, >>>> kaiyou. >>>> >>>> >>>>

Fixed with https://github.com/dovecot/core/commit/4f051c3082080b9d69ef12c3720c683cff34b...

Aki Tuomi