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

...

...

...

...

...

>> 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