[lwip-users] http_sent cb shows 1 byte trailer [RAW]

[Chris Strahm]

Working on getting my server code finished, everything working pretty good now.  However two questions:

 

After I setup my file to send in http_rcve(), and my send_data() function starts getting called by lwip, I check the http_sent() cb and inspect the len parameter.  This is suppose to reflect the bytes sent I think.

 

Showing the debug output from my httpd, I always see a listing at the end with a length of 1 byte.  That seems odd to me.  Also, it appears that the close_conn() function always gets called twice, once with arg pointer active, and the second time with it NULL.  Not sure what to make of that.  This happens with basically all the files whether html, gif, or jpg.  But the web pages display perfectly in both IE and FF even with fast repeated refreshes.  Wireshark shows all Green.

 

I searched the web about this, and I found an article from BYU that mentions the same thing I am seeing, about the trailing 1 byte reported by http_sent().  But they don't really say what the explanation is.  I basically tried their code and didn't see any changes.

 

http://www.et.byu.edu/groups/ececmpsysweb/cmpsys.2005.winter/teams/supermpeg/groups/supermpeg/endpages/Ammons_proj.php

 

Their code has notes about the cb http_sent() "len" parameter being unreliable.

 

The debug listing below shows the typically send results on a file.  As you can see there is a listing near the end where http_sent() still has 1 byte remaining.  Also, you can see where the close_conn() gets called twice, the first time with major data remaining. 

 

What does the 1 byte length mean?

Why does close get called twice?

 

Thanks,  Chris.

 

 

CON>Sending /lx777.ssi  0x400075cc
CON>Content-length: 20718
CON>max send len 2920
CON>max send len 2920
CON>max send len 2920
CON>max send len 2920
CON>max send len 2920
CON>max send len 2920
CON>max send len 2920
CON>max send len 2920
CON>max send len 2920
CON>max send len 2920
CON>tcp_output
CON>http_sent /lx777.ssi 0x400075cc remaining:19258
CON>tcp_output
CON>http_sent /lx777.ssi 0x400075cc remaining:17034
CON>tcp_output
CON>http_sent /lx777.ssi 0x400075cc remaining:14114
CON>tcp_output
CON>http_sent /lx777.ssi 0x400075cc remaining:11958
CON>tcp_output
CON>http_sent /lx777.ssi 0x400075cc remaining:9734
CON>tcp_output
CON>http_sent /lx777.ssi 0x400075cc remaining:6814
CON>tcp_output
CCON>http_sent /lx777.ssi 0x400075cc remaining:4658
CON>tcp_output
CON>End of File /lx777.ssi
CON>Closing Connection 0x400075cc remaining=4658 (http_state=arg was Active here)
CON>http_sent hs=NULL 0x400075cc 2224 (sent, hs now NULL)
CON>http_sent hs=NULL 0x400075cc 2434 (sent, hs now NULL)
CON>http_sent hs=NULL 0x400075cc 1 (sent, hs now NULL)
CON>Closing Connection 0x400075cc   (http_state=arg was NULL here)

 

 

 

lwip_1.pcap
Description: Binary data