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From Chen Chien-Yu <honer...@gmail.com>
Subject Re: [users@httpd] Re: HTTP doesn't work after upgrading from 2.0.55 to 2.2.15
Date Wed, 02 Jun 2010 01:25:01 GMT
Hi All,

I am sure the problem is irrelevant to the CGI and mod_CGI. Because I try to
load a image file, the result is the same.
And I forget to say one thing, the platform I'm using is a PowerPC
architecture in an embedded system, so the apache is cross-compiled.

I guess it might be the cause, and may be located in APR or APR-util?

Anyway, that's really a tough issue for me...

Thanks

On Tue, Jun 1, 2010 at 4:25 PM, Chen Chien-Yu <honercek@gmail.com> wrote:

> Hi All,
>
> After using the strace tools, there's a new find. It will stop at the
> function call read()....
> A infinite loop happens in server/core_filters.c ap_core_input_filter().
>
>
>     if (mode == AP_MODE_EATCRLF) {
>         apr_bucket *e;
>         const char *c;
>
>         while (1) {
>             if (APR_BRIGADE_EMPTY(ctx->b)) {
>                 return APR_EOF;
>        }
>
>             e = APR_BRIGADE_FIRST(ctx->b);
>
>             rv = apr_bucket_read(e, &str, &len, APR_NONBLOCK_READ); *<---------------
> I guess this is the place gets stuck...*
>
>             if (rv != APR_SUCCESS) {
>                 return rv;                *<---- successful case will exit
> via this place with the value of rv = 11. (APR_ENOSOCKET ??)*
>      }
>
>             c = str;
>             while (c < str + len) {
>                 if (*c == APR_ASCII_LF)
>                     c++;
>                 else if (*c == APR_ASCII_CR && *(c + 1) == APR_ASCII_LF)
>                     c += 2;
>                 else
>                     return APR_SUCCESS;
>             }
>
>             /* If we reach here, we were a bucket just full of CRLFs, so
>              * just toss the bucket. */
>             /* FIXME: Is this the right thing to do in the core? */
>             apr_bucket_delete(e);
>         }
>
> I don't know why it's stuck here, and does it relate to the zero-chunk
> packet that doesn't see in the client?
>
> Thanks
>
> Best regards,
> honercek
>
> On Mon, May 31, 2010 at 8:14 AM, Chen Chien-Yu <honercek@gmail.com> wrote:
>
>> Hi William,
>>
>> I'm sorry to confuse you.
>> Please let me reorganize the problem and my observations.
>>
>> Client ---- HTTP ---- Apache ---- Mod-CGI ---- xxx.cgi ---- login.html
>>
>>
>> A client(browser) access the URI, http://xxx.xxx.xxx/xxx.cgi which is
>> located on the Apache 2.2.15, but finally what it got was only the content
>> of page and lack of the last chunk, which made the browser stuck and
>> loading continually.
>>
>> xxx.cgi is written with the GNU library looks like this<http://mail-archives.apache.org/mod_mbox/httpd-users/201005.mbox/%3CAANLkTikTxKb8CV-ezRKfmaN0GZS4c3-Mw7V8kN1vYW51@mail.gmail.com%3E>.
>> It will read the file login.html and put it on the network stream to the
>> client.
>> I've also tried to return a string only "Hello" instead of the file
>> content, the result is the same stuck.
>>
>> If the directive HTTPS exists (Listen 443), the HTTP will not work
>> correctly(Case A). But if I comment out the directives HTTPS, the HTTP will
>> work without any problem(Case B). So I compared them by adding some debug
>> messages in Apache.
>> There is another case that is workable as well, even the HTTP and HTTPS
>> exist at the same time.(disable the KeepAlive mechanism, but it a must
>> option for us in the performance point of view)
>>
>> All the output filters are the built in ones, I didn't insert any one I
>> write. (There are the filters I found, byterange, content length,
>> http_header, http_outerror, core)
>>
>>
>> ============================================================================================
>>
>> Client ---- HTTP ---- Apache ---- Mod-CGI ---- xxx.cgi ---- login.html
>>
>> In Mod-CGI, there's a function called cgi_bucket_read(). It's a read
>> method of CGI bucket: polls on stdout of the child. I found it read 806
>> bytes via a function call cgi_read_stdout() from stdout followed by a 0 byte
>> read.
>>
>> Then in Apache core filter, a function called ap_core_output_filter(), in
>> the case of EOS, the function apr_bucket_read() inside it reads two times in
>> a row, a 0 byte followed by a 5 bytes(0\r\n\r\n). Seems that, the 5 bytes
>> bucket is the one the client expect.
>>
>> Until now, there's no difference between Case A and Case B.
>>
>> After this, I found the successful one(Case B) will flush out a 5 bytes
>> bucket in the core filter. I have no idea who triggers this event. But
>> nothing happens in Case A.
>>
>> Thanks
>>
>> Best regards,
>> honercek
>>
>>
>> On Fri, May 28, 2010 at 8:58 PM, William A. Rowe Jr. <wrowe@rowe-clan.net
>> > wrote:
>>
>>> On 5/28/2010 3:08 AM, Chen Chien-Yu wrote:
>>> > Hi William,
>>> >
>>> > I gave you the incorrect information in the previous post.
>>> >
>>> > cgi_read_stdout() in cgi_bucket_read() in mod_cgi.c, the data length is
>>> > 806 followed by 0. (Not the 0 and 5 buckets)
>>> > then ap_core_output_filter() found a 0 length bucket, and appended a
>>> > last-chunk bucket?
>>>
>>> What you describe sounds like correct HTTP behavior.  The last-chunk
>>> bucket is being correctly transmitted after the 806 byte bucket?
>>>
>>> I'm losing track of what the exact problem is.
>>>
>>> Also do you insert any additional filters for the output of this filter?
>>>
>>
>>
>

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