From: Florian Manschwetus Date: Tue, 29 Mar 2016 06:01:38 GMT Subject: AW: Problem with git-http-backend.exe as iis cgi Message-ID: In-Reply-To: <20160310155522.1dee53cf95fead8cfd4e178a@domain007.com> Hi, I put together a first patch for the issue. Mit freundlichen Grüßen / With kind regards Florian Manschwetus E-Mail: manschwetus@cs-software-gmbh.de Tel.: +49-(0)611-8908534   CS Software Concepts and Solutions GmbH Geschäftsführer / Managing director: Dr. Werner Alexi Amtsgericht Wiesbaden HRB 10004 (Commercial registry) Schiersteiner Straße 31 D-65187 Wiesbaden Germany Tel.: 0611/8908555 -----Ursprüngliche Nachricht----- Von: Konstantin Khomoutov [mailto:kostix+git@007spb.ru] Gesendet: Donnerstag, 10. März 2016 13:55 An: Florian Manschwetus Cc: git@vger.kernel.org Betreff: Re: Problem with git-http-backend.exe as iis cgi On Thu, 10 Mar 2016 07:28:50 +0000 Florian Manschwetus wrote: > I tried to setup git-http-backend with iis, as iis provides proper > impersonation for cgi under windows, which leads to have the > filesystem access performed with the logon user, therefore the > webserver doesn't need generic access to the files. I stumbled across > a problem, ending up with post requests hanging forever. After some > investigation I managed to get it work by wrapping the http-backend > into a bash script, giving a lot of control about the environmental > things, I was unable to solve within IIS configuration. The > workaround, I use currently, is to use "/bin/head -c ${CONTENT_LENGTH} > | ./git-http-backend.exe", which directly shows the issue. Git > http-backend should check if CONTENT_LENGTH is set to something > reasonable (e.g. >0) and should in this case read only CONTENT_LENGTH > bytes from stdin, instead of reading till EOF what I suspect it is > doing currently. The rfc [1] states in its section 4.2: | A request-body is supplied with the request if the CONTENT_LENGTH is | not NULL. The server MUST make at least that many bytes available for | the script to read. The server MAY signal an end-of-file condition | after CONTENT_LENGTH bytes have been read or it MAY supply extension | data. Therefore, the script MUST NOT attempt to read more than | CONTENT_LENGTH bytes, even if more data is available. However, it is | not obliged to read any of the data. So yes, if Git currently reads until EOF, it's an error. The correct way would be: 1) Check to see if the CONTENT_LENGTH variable is available in the environment. If no, read nothing. 2) Otherwise read as many bytes it specifies, and no more. 1. https://www.ietf.org/rfc/rfc3875 --- http-backend.c.orig 2016-03-29 07:29:32.694722500 +0200 +++ http-backend.c 2016-03-29 07:58:50.801482700 +0200 @@ -277,16 +277,32 @@ */ static ssize_t read_request(int fd, unsigned char **out) { - size_t len = 0, alloc = 8192; - unsigned char *buf = xmalloc(alloc); + unsigned char *buf = null; + size_t len = 0; + /* get request size */ + size_t req_len = git_env_ulong("CONTENT_LENGTH", + 0); + + /* check request size */ + if (max_request_buffer < req_len) { + die("request was larger than our maximum size (%lu);" + " try setting GIT_HTTP_MAX_REQUEST_BUFFER", + max_request_buffer); + } + + if (req_len <= 0) { + *out = null; + return 0; + } + + /* allocate buffer */ + buf = xmalloc(req_len) - if (max_request_buffer < alloc) - max_request_buffer = alloc; while (1) { ssize_t cnt; - cnt = read_in_full(fd, buf + len, alloc - len); + cnt = read_in_full(fd, buf + len, req_len - len); if (cnt < 0) { free(buf); return -1; @@ -294,21 +310,18 @@ /* partial read from read_in_full means we hit EOF */ len += cnt; - if (len < alloc) { + if (len < req_len) { + /* TODO request incomplete?? */ + /* maybe just remove this block and condition along with the loop, */ + /* if read_in_full is prooven reliable */ *out = buf; return len; + } else { + /* request complete */ + *out = buf; + return len; + } - - /* otherwise, grow and try again (if we can) */ - if (alloc == max_request_buffer) - die("request was larger than our maximum size (%lu);" - " try setting GIT_HTTP_MAX_REQUEST_BUFFER", - max_request_buffer); - - alloc = alloc_nr(alloc); - if (alloc > max_request_buffer) - alloc = max_request_buffer; - REALLOC_ARRAY(buf, alloc); } }