HTTP::collect and HTTP::payload corrupt?

I am trying to create an iRule that, when a response is sent back to the client (the client initiates a GET request for a file, in this case an image), it will collect the body. The iRule should then POST that content back through the virtual server, with some modified headers.

Unfortunately it seems like for whatever reason the payload in the POST has been truncated (i have confirmed this with wireshark dumps, although i cant work out exactly by how many bytes its been truncated), I can't for the life of me work out why! I've posted the relevant logic below (i have truncated some parts that are irrelevant although if you want to i can post the full irule, it's still a work in progress however!). The image I am testing with is 7737 bytes in size and all my logs indicate that it is getting the correct content length of 7737 bytes...does anyone know what the issue could be?

when HTTP_RESPONSE {

set contentlength [HTTP::header Content-Length]

if { $debug>=3 } { log local0.info "$castoruri found in production castor domain. Collecting file of length $contentlength to POST back to $original_partition environment" }

HTTP::collect $contentlength

}

when HTTP_RESPONSE_DATA {

if { $debug>=3 } { log local0.info "HTTP_RESPONSE_DATA triggered for castoruri $castoruri" }

set payload [HTTP::payload]

This POSTs back through the iRule like a client request, and so the iRule will trigger HTTP_REQUEST again

if { $debug>=3 } {log local0.info "REQUEST IS POST $original_path HTTP/1.1\r\nHost: $original_castordomain\r\nContent-Length: $contentlength\r\n\r\n$payload" }

HTTP::retry "POST $original_path HTTP/1.1\r\nHost: $original_castordomain\r\nX-Forwarded-Host: $original_castordomain\r\nContent-Length: $contentlength\r\n\r\n$payload\r\n"

}

All variables above are present and correct, what am I missing? Any help much appreciated :)

Logs:

: /default/JAMES12.JPG found in production castor domain. Collecting file of length 7737 to POST back to qa environment

: HTTP_RESPONSE_DATA triggered for castoruri /default/JAMES12.JPG

: REQUEST IS POST /JAMES12.JPG HTTP/1.1 Host: castor.qa.rightmove.com Content-Length: 7737 ÿØÿà��020JFIF��001001001��`��`����ÿþ��036LEAD Technologies Inc. V1.01ÿÛ��C��003002002002002002003002002002003003003003004006004004004004004010006006005006011010 011010011011 014017014 013016013011011 021 016017020020021020 014022023022020023017020020020ÿÛ��C001003003003004003004010004004010020013011013020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020020ÿÀ��021010��´��‡003001"��002021001003021001ÿÄ��035����001005001001001001������������������005��003004006007010002001011ÿÄ��B020��002001003002003004007006004003007005������001002003��004021005!0060221007023AQ024"aq�‘¡0102B±Á0253RÑb¢Â026$‚’²áñ4CSƒ”ÿÄ��033001��002002003001����������������������003004002005��001006007ÿÄ��4021��002001003002004004003006007001����������001002��003004021!1005022023A006Qaq"2‘024B¡±Ñð0070253Rb�ÁÿÚ��014003001��002021003021��?��µiœe*C004·021jЬÜØRRP0pzîjÍo¯i2ÜMmtöí$001‹‰l˜025ÁßÖ025Õ—¿g016Íî—Ñ¡³¸·D˧ç005ŽýG°P{ß³g É5Ö¡o¨H¯z¯013«D010034ç031Î|016õ³N–àÂ013Š½Ìç…›†.R6Qf{Â@1Þ•$û025‡¶›ŸIÒ˜1�ïbÇOÁ(ÿ��)006¶035oì©5͵¥…†§hæÆVœ™024ŽñX�W033ÿ��OÖ²n?û,v�l8‡QÐôäŸø†$±ô{•Gþpr1Ì010<™ùb„É�Œ*\·Þ•{øm­NM