Re: [Freeswitch-users] Spidermokey_curl problem? Sanity check please

16 Jul 2008

      I’ve opened bug MODLANG-71.  I have a feeling you’ll need to check content-length, but I am not sure.  I’m actually playing around with the source locally and trying to find a fix as well.  At least, a temp fix so my code will work J.

From: freeswitch-users-bounces@lists.freeswitch.org [mailto:freeswitch-users-bounces@lists.freeswitch.org] On Behalf Of Michael Jerris
Sent: July 15, 2008 6:31 PM
To: freeswitch-users@lists.freeswitch.org
Subject: Re: [Freeswitch-users] Spidermokey_curl problem? Sanity check please

The analysis looks good, but how in the API do we know when the response is complete?  Can you please open a bug on jira.freeswitch.org for this so we can track it.

Thanks

Mike

On Jul 15, 2008, at 8:12 PM, "Simon Tang" <simon@airg.com> wrote:

	Hello,

	I’ve been making Javascript curl requests and have found that larger requests sometimes come back incomplete.  This is what I am doing in javascript:

	------------

	function callback(string, arg)

	{

	    console_log("info", "returned body:" + string + "\n");

	    return true;

	}

	var curl = new CURL();

	var blah = curl.run("GET", url, args, callback, arg, "");

	--------------

	comparing ‘string’ with tcpdump, I found that ‘string’ is definitely incomplete vs. tcpdump.

	I’ve looked into spidermokey_curl.c and found this code (excerpts):

	static size_t file_callback(void *ptr, size_t size, size_t nmemb, void *data)

	{…}

	curl_easy_setopt(co->curl_handle, CURLOPT_WRITEFUNCTION, file_callback);

	curl_easy_setopt(co->curl_handle, CURLOPT_WRITEDATA, (void *) co);

	I had the suspicion that the callback is getting a partial response and passing it into the JS object as a completed response:

	-          From http://curl.netmirror.org/libcurl/c/curl_easy_setopt.html: “The callback function will be passed as much data as possible in all invokes, but you cannot possibly make any assumptions. It may be one byte, it may be thousands. The maximum amount of data that can be passed to the write callback is defined in the curl.h header file: CURL_MAX_WRITE_SIZE.”  >From this, I think that it is the callback’s responsibility to ensure that the complete response was received and to save the data somewhere.

	To confirm my suspicion, I replaced the callback function in spidermonkey_curl.c with vanilla logging and took out the JSAPI references:

	static size_t file_callback(void *ptr, size_t size, size_t nmemb, void *data)

	{

	    register unsigned int realsize = (unsigned int) (size * nmemb);

	switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_DEBUG,"BODY STUFF::::::%s\n", (char*) ptr);

	return realsize;

	}

	I recompiled and reproduced the offending http request.  I found that the log is called twice, with each log comprising both pieces of the complete response.  When I reverted back to the original file_callback function and added a log in there, the log only recorded the first part of the response (incomplete).

	I’m not sure if I’m using this correctly or if my analysis is correct, so if someone can provide me some feedback, that’d be great.  If it’s a legit bug, I can file it.

	Simon Tang

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