buglwIP - A Lightweight TCP/IP stack - Bugs: bug #50844, Wrong SSI tag handling if tag ends...


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bug #50844: Wrong SSI tag handling if tag ends exactly at the end of 2xMSS buffer

Submitted by:  Dmitry <gdi>
Submitted on:  Fri 21 Apr 2017 07:31:17 AM UTC  
Category:  apps Severity:  3 - Normal
Item Group:  Faulty Behaviour Status:  Fixed
Privacy:  Public Assigned to:  Simon Goldschmidt <goldsimon>
Open/Closed:  Closed Planned Release:  None
lwIP version:  1.4.1

Mon 24 Apr 2017 08:34:36 PM UTC, comment #4: 

Should be fixed, thanks for reporting.
And thanks for pushing me into adding 'contrib/addons/http/*' ;-)

Simon Goldschmidt <goldsimon>
Project AdministratorIn charge of this item.
Mon 24 Apr 2017 07:58:40 AM UTC, comment #3: 

So I found the version of http server with which I'm working. This is httpserver_raw from CVS repository http://cvs.savannah.gnu.org/viewvc/*checkout*/lwip/contrib/apps/httpserver_raw/httpd.c?revision=1.45

Dmitry <gdi>
Mon 24 Apr 2017 07:21:22 AM UTC, comment #2: 

Yes I'm using FatFS to store files. But I'm also working with httpserver_raw from Texas Instruments TivaWare library and there is no LWIP_HTTPD_DYNAMIC_FILE_READ setting. Maybe this is some old example of http server. But this issue is related also to a last httpd.c from lwip v2.0.x apps. I didn't test it with static files which are stored in internal flash memory.
For a v2.0.x the changes should be made in http_send_data_ssi function in a 1209 line:
while((ssi->tag_state == TAG_SENDING) || (ssi->parse_left) && (err == ERR_OK)) {

Dmitry <gdi>
Fri 21 Apr 2017 01:36:37 PM UTC, comment #1: 

To clarify: this only happens for LWIP_HTTPD_DYNAMIC_FILE_READ. And 2*MSS because the code limits to 2*MSS by default.

Simon Goldschmidt <goldsimon>
Project AdministratorIn charge of this item.
Fri 21 Apr 2017 07:31:17 AM UTC, original submission:  

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 example.

Dmitry <gdi>


Attached Files
file #40461:  hs-last-tag.png added by gdi (50KiB - image/png)


Depends on the following items: None found

Items that depend on this one: None found


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    Follow 4 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2017-04-24 goldsimon StatusNone => Fixed
        Assigned toNone => goldsimon
        Open/ClosedOpen => Closed
    2017-04-21 gdi Attached File- => Added hs-last-tag.png, #40461

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