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[lwip-devel] [bug #50844] Wrong SSI tag handling if tag ends exactly at

From: Dmitry
Subject: [lwip-devel] [bug #50844] Wrong SSI tag handling if tag ends exactly at the end of 2xMSS buffer
Date: Fri, 21 Apr 2017 03:31:18 -0400 (EDT)
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:53.0) Gecko/20100101 Firefox/53.0


                 Summary: Wrong SSI tag handling if tag ends exactly at the
end of 2xMSS buffer
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: gdi
            Submitted on: Fri 21 Apr 2017 07:31:17 AM UTC
                Category: apps
                Severity: 3 - Normal
              Item Group: Faulty Behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None
            lwIP version: 1.4.1



I found a trouble in SSI handling in httpsever_raw application of lwip v1.4.1
and the same issue presented in v2.0.x too.
The issue is appeared if you have a long *.shtml file which size more of equal
to 5840 bytes and if you have SSI tag which will has its closing '>' symbol in
a 5840-th byte. In this case the hs->tag_state will switch to TAG_SENDING
state and we will go to a next revolution of 'while' loop. But the
hs->parse_left = 0 here and we will go out of loop without sending this last
tag. And we won't send the continue of *shtml file too. It will ends here.
I've catch this situation in debugger see the attachment.
I'm also found a solution:
I've add the checking for a TAG_SENDING state to the loop expression.

    /* We have sent all the data that was already parsed so continue parsing
     * the buffer contents looking for SSI tags. */
    while((hs->tag_state == TAG_SENDING) || (hs->parse_left) && (err ==
ERR_OK)) {

The same fix can be applied in appropriate place in lwip v2.0.x httpd


File Attachments:

Date: Fri 21 Apr 2017 07:31:17 AM UTC  Name: hs-last-tag.png  Size: 50kB   By:



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