[lwip-users] HTTP transfer delayed by errors with Firefox - lwIP 1.3.0 on Xilinx Microblaze

[Lou Cypher]

I'm using lwIP on Xilinx (S3A) Microblaze, and I used both their application
note XAPP1026 (heavily modified, since it's quite buggy) and the stock raw httpd
in contrib (with a few changes).

My problem arises when I serve a page with "large" content, like with an image
of some KiB.
The web page is composed by some parts, in this example the main file
  "m5.html" has references to
   "css/main.css" and
   "images/mainlogo.png"
What happens is that after "m5.html" has been loaded, Firefox opens
"images/mainlogo.png", then *during* this data transfer, it requests 
"css/main.css".
This behavior seems to confuse lwIP, that "forgets" to complete data transfer
for the CSS file, and that's not all.
After a couple of seconds it calls the tcp_poll() handler, that has not yet data
to send, because the HTTP/"GET css/main.css" request has *not* been delivered to
the tcp_recv() handler.

Trying with IE7, that doesn't seem to use interleaved reads, everything goes
fine, no matter the type/size of files.
Firefox appears to work well when I download single files, that go smooth even
when tens or hundreds of KiB.

Options in lwipopts.h are almost the default ones, beside memory allocation,
that on this board is quite generous.

This is a short log of messages inserted in httpd.c, in functions http_poll() -
the "POLL" message, printed RS-232 when incrementing number of retries - and
http_rcv() - when I recognize file to send and start it.
Numbers in parentheses are file sizes, numbers in brackets is system time in
milliseconds.
-----------------------------------------------------------------------------
httpd: GET /m5.html (383)  {31485}
httpd: close conn
httpd: GET /images/mainlogo.png (7728)  {31549}
httpd: close conn
httpd: POLL, left: 0, file: 0, data: 0, retr.: 1
             loc.: 80, rem.: 3407, state: 4  {33481}
httpd: GET /css/main.css (1300)  {34540}
httpd: close conn
-----------------------------------------------------------------------------

The same numbers can be seen on the attached log from Wireshark.
Port 3407 is opened for requesting main.css (in frame 23) but it gets no reply,
then on frame 35 there's a retransmission by client and it finally gets
answered, but it's three seconds later!

- Is there some option I'm missing?
- The function called on tcp_poll() handler works for output *and* input? How to
handle broken/incomplete input with it?


Lou


No.     Time        Source                Destination           Protocol Info
      1 0.000000    02:30:05:3f:45:17     Broadcast             ARP      Who 
has 192.168.0.131?  Tell 192.168.0.130
      2 0.000766    Xilinx_00:01:02       02:30:05:3f:45:17     ARP      
192.168.0.131 is at 00:0a:35:00:01:02
      3 0.000775    192.168.0.130         192.168.0.131         TCP      3403 > 
80 [SYN] Seq=0 Win=16384 Len=0 MSS=1460
      4 0.001453    192.168.0.131         192.168.0.130         TCP      80 > 
3403 [SYN, ACK] Seq=0 Ack=1 Win=6144 Len=0 MSS=1460
      5 0.001487    192.168.0.130         192.168.0.131         TCP      3403 > 
80 [ACK] Seq=1 Ack=1 Win=17520 Len=0
      6 0.001814    192.168.0.130         192.168.0.131         HTTP     GET 
/m5.html HTTP/1.1 
      7 0.002638    192.168.0.131         192.168.0.130         TCP      80 > 
3403 [ACK] Seq=1 Ack=432 Win=6144 Len=0
      8 0.009252    192.168.0.131         192.168.0.130         HTTP     
HTTP/1.1 200 OK  (text/html)
      9 0.063292    192.168.0.130         192.168.0.131         TCP      3403 > 
80 [FIN, ACK] Seq=432 Ack=469 Win=17052 Len=0
     10 0.064852    192.168.0.131         192.168.0.130         TCP      80 > 
3403 [FIN, ACK] Seq=469 Ack=433 Win=6143 Len=0
     11 0.064877    192.168.0.130         192.168.0.131         TCP      3403 > 
80 [ACK] Seq=433 Ack=470 Win=17052 Len=0
     12 0.067697    192.168.0.130         192.168.0.131         TCP      3406 > 
80 [SYN] Seq=0 Win=16384 Len=0 MSS=1460
     13 0.068432    192.168.0.131         192.168.0.130         TCP      80 > 
3406 [SYN, ACK] Seq=0 Ack=1 Win=6144 Len=0 MSS=1460
     14 0.068478    192.168.0.130         192.168.0.131         TCP      3406 > 
80 [ACK] Seq=1 Ack=1 Win=17520 Len=0
     15 0.071566    192.168.0.130         192.168.0.131         HTTP     GET 
/images/mainlogo.png HTTP/1.1 
     16 0.072084    192.168.0.130         192.168.0.131         TCP      3407 > 
80 [SYN] Seq=0 Win=16384 Len=0 MSS=1460
     17 0.072407    192.168.0.131         192.168.0.130         TCP      80 > 
3406 [ACK] Seq=1 Ack=427 Win=6144 Len=0
     18 0.086365    192.168.0.131         192.168.0.130         TCP      [TCP 
segment of a reassembled PDU]
     19 0.086842    192.168.0.131         192.168.0.130         TCP      [TCP 
segment of a reassembled PDU]
     20 0.086897    192.168.0.130         192.168.0.131         TCP      3406 > 
80 [ACK] Seq=427 Ack=1547 Win=17520 Len=0
     21 0.087358    192.168.0.131         192.168.0.130         TCP      80 > 
3407 [SYN, ACK] Seq=0 Ack=1 Win=6144 Len=0 MSS=1460
     22 0.087412    192.168.0.130         192.168.0.131         TCP      3407 > 
80 [ACK] Seq=1 Ack=1 Win=17520 Len=0
     23 0.088134    192.168.0.130         192.168.0.131         HTTP     GET 
/css/main.css HTTP/1.1 
     24 0.089729    192.168.0.131         192.168.0.130         TCP      [TCP 
segment of a reassembled PDU]
     25 0.091644    192.168.0.131         192.168.0.130         TCP      [TCP 
segment of a reassembled PDU]
     26 0.091723    192.168.0.130         192.168.0.131         TCP      3406 > 
80 [ACK] Seq=427 Ack=4467 Win=17520 Len=0
     27 0.092251    192.168.0.131         192.168.0.130         TCP      [TCP 
segment of a reassembled PDU]
     28 0.093611    192.168.0.131         192.168.0.130         TCP      [TCP 
segment of a reassembled PDU]
     29 0.093693    192.168.0.130         192.168.0.131         TCP      3406 > 
80 [ACK] Seq=427 Ack=7387 Win=17520 Len=0
     30 0.094252    192.168.0.131         192.168.0.130         HTTP     
HTTP/1.1 200 OK  (PNG)
     31 0.094292    192.168.0.131         192.168.0.130         TCP      80 > 
3406 [FIN, ACK] Seq=7815 Ack=427 Win=6144 Len=0
     32 0.094313    192.168.0.130         192.168.0.131         TCP      3406 > 
80 [ACK] Seq=427 Ack=7816 Win=17092 Len=0
     33 0.108413    192.168.0.130         192.168.0.131         TCP      3406 > 
80 [FIN, ACK] Seq=427 Ack=7816 Win=17092 Len=0
     34 0.109108    192.168.0.131         192.168.0.130         TCP      80 > 
3406 [ACK] Seq=7816 Ack=428 Win=6143 Len=0
     35 3.101648    192.168.0.130         192.168.0.131         HTTP     [TCP 
Retransmission] GET /css/main.css HTTP/1.1 
     36 3.102477    192.168.0.131         192.168.0.130         TCP      80 > 
3407 [ACK] Seq=1 Ack=431 Win=6144 Len=0
     37 3.111729    192.168.0.131         192.168.0.130         HTTP     
HTTP/1.1 200 OK  (text/css)
     38 3.210211    192.168.0.130         192.168.0.131         TCP      3407 > 
80 [FIN, ACK] Seq=431 Ack=1386 Win=16135 Len=0
     39 3.211729    192.168.0.131         192.168.0.130         TCP      80 > 
3407 [FIN, ACK] Seq=1386 Ack=432 Win=6143 Len=0
     40 3.211779    192.168.0.130         192.168.0.131         TCP      3407 > 
80 [ACK] Seq=432 Ack=1387 Win=16135 Len=0

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