id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
1496	Issue while logging after client sent duplicate header	fffilimonov@…		"Found in a wild. Some proxy from china.
Possible UC-browser.
{{{
X-UCBrowser-UA: dv(Mi A1);pr(UCBrowser/12.0.0.1088);ov(Android 8.0.0);ss(423*752);pi(1080*1920);bt(GJ);pm(1);bv(1);nm(0);im(0);sr(0);nt(1);bi(355);fi(145);dn(25926126305-886b8f7e);ai(720089404747345);
User-Agent: Mozilla/5.0 (Linux; U; Android 8.0.0; en-US; Mi A1 Build/OPR1.170623.026) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/57.0.2987.108 UCBrowser/12.0.0.1088 Mobile Safari/537.36
}}}

Configuration:
{{{
		if ($time_iso8601 ~ ""^(\d{4})-(\d{2})-(\d{2})"") {
			set $year $1;
			set $month $2;
			set $day $3;
		}

		access_log /sites/$host/logs/${year}_${month}_${day}.log;
}}}

Request to reproduce:

{{{
printf ""GET / HTTP/1.1\r\nHost: test.com\r\nIf-None-Match: \""5a2027cf-6d6\""\r\nIf-None-Match: 13:10009~2:10009:4521798~1:10009:4521798\r\n\r\n"" | netcat 127.0.0.1 80
}}}

The problem:
{{{
2018/02/26 22:05:08 [debug] 58329#0: *5 http close request
2018/02/26 22:05:08 [debug] 58329#0: *5 http log handler
2018/02/26 22:05:08 [warn] 58329#0: *5 using uninitialized ""year"" variable while logging request, client: 127.0.0.1, server: , request: ""GET /trk5.js?867435 HTTP/1.1"", host: ""test.com""
2018/02/26 22:05:08 [warn] 58329#0: *5 using uninitialized ""month"" variable while logging request, client: 127.0.0.1, server: , request: ""GET /trk5.js?867435 HTTP/1.1"", host: ""test.com""
2018/02/26 22:05:08 [warn] 58329#0: *5 using uninitialized ""day"" variable while logging request, client: 127.0.0.1, server: , request: ""GET /trk5.js?867435 HTTP/1.1"", host: ""test.com""
2018/02/26 22:05:08 [debug] 58329#0: *5 http script copy: ""/sites/""
2018/02/26 22:05:08 [debug] 58329#0: *5 http script var: ""test.com""
2018/02/26 22:05:08 [debug] 58329#0: *5 http script copy: ""/logs/""
2018/02/26 22:05:08 [debug] 58329#0: *5 http script var: """"
2018/02/26 22:05:08 [debug] 58329#0: *5 http script copy: ""_""
2018/02/26 22:05:08 [debug] 58329#0: *5 http script var: """"
2018/02/26 22:05:08 [debug] 58329#0: *5 http script copy: ""_""
2018/02/26 22:05:08 [debug] 58329#0: *5 http script var: """"
2018/02/26 22:05:08 [debug] 58329#0: *5 http script copy: "".log""
2018/02/26 22:05:08 [debug] 58329#0: *5 http log ""/sites//logs/__.log""
}}}

But the real proxy sends request where Host header located after f-None-Match:
{{{
printf ""GET / HTTP/1.1\r\nIf-None-Match: \""5a2027cf-6d6\""\r\nIf-None-Match: 13:10009~2:10009:4521798~1:10009:4521798\r\nHost: test.com\r\n\r\n"" | netcat 127.0.0.1 80
}}}
In this case $host is empty:
{{{
2018/02/26 22:14:52 [debug] 58332#0: *7 http close request
2018/02/26 22:14:52 [debug] 58332#0: *7 http log handler
2018/02/26 22:14:52 [warn] 58332#0: *7 using uninitialized ""year"" variable while logging request, client: 127.0.0.1, server: , request: ""GET / HTTP/1.1""
2018/02/26 22:14:52 [warn] 58332#0: *7 using uninitialized ""month"" variable while logging request, client: 127.0.0.1, server: , request: ""GET / HTTP/1.1""
2018/02/26 22:14:52 [warn] 58332#0: *7 using uninitialized ""day"" variable while logging request, client: 127.0.0.1, server: , request: ""GET / HTTP/1.1""
2018/02/26 22:14:52 [debug] 58332#0: *7 http script copy: ""/sites/""
2018/02/26 22:14:52 [debug] 58332#0: *7 http script var: """"
2018/02/26 22:14:52 [debug] 58332#0: *7 http script copy: ""/logs/""
2018/02/26 22:14:52 [debug] 58332#0: *7 http script var: """"
2018/02/26 22:14:52 [debug] 58332#0: *7 http script copy: ""_""
2018/02/26 22:14:52 [debug] 58332#0: *7 http script var: """"
2018/02/26 22:14:52 [debug] 58332#0: *7 http script copy: ""_""
2018/02/26 22:14:52 [debug] 58332#0: *7 http script var: """"
2018/02/26 22:14:52 [debug] 58332#0: *7 http script copy: "".log""
2018/02/26 22:14:52 [debug] 58332#0: *7 http log ""/sites//logs/__.log""
2018/02/26 22:14:52 [debug] 58332#0: *7 add cleanup: 00007FC32D005BE8
2018/02/26 22:14:52 [crit] 58332#0: *7 open() ""/sites//logs/__.log"" failed (2: No such file or directory) while logging request, client: 127.0.0.1, server: , request: ""GET / HTTP/1.1""
}}}"	defect	closed	minor		nginx-core	1.13.x	invalid		fffilimonov@…	Darwin 16.7.0 Darwin Kernel Version 16.7.0: Thu Jun 15 17:36:27 PDT 2017; root:xnu-3789.70.16~2/RELEASE_X86_64 x86_64	"nginx version: nginx/1.13.10
built by clang 8.1.0 (clang-802.0.42)
configure arguments: --with-debug"