Category Archives: cURL and libcurl

curl and/or libcurl related

Fresh CA Cert Bundle Anyone?

cURLThe popular ca extract service on the curl web site converts the Firefox ca certs into a PEM file suitable for use with curl, wget or anything else OpenSSL-based that likes PEM formatted CA cert bundles.

The main script was fixed yesterday as it was previously getting a nightly source code snapshot to get the "magic" file to convert from, but I noticed they stopped updating the nightly source snapshots a good while ago so the updates had stopped!

Now, the script only gets the actually needed certdata file and converts it, so now it downloads a lot less data in vain and it also thus runs much faster. Now the PEM files offered on that page are up-to-date with the most recent Firefox.

Crashing Firefox Goes libcurl

I guess I haven't been paying attention lately, but I stumbled over the Breakpad project, which incidentally is gonna be used as crash reporting tool for Firefox 3, and it uses libcurl: "On Linux, libcurl is used for this function, as it is the closest thing to a standard HTTP library available on that platform."libcurl

The wording implies that it uses something else on Mac OS X, but I'm not aware of any standard HTTP library on it. Am I missing something or are they going libcurl there too?

Also, I wonder if using different HTTP libraries on different platforms instead of a single one isn't just begging for more problems than what it solves? As far as I know, libcurl has a few upsides compared to wininet for example. Of course, I'm not the man to tell how they should do their stuff.

libcurl DNS resolve problems on Leopard

libcurlI found this article by Jungle Dave titled Leopard DNS Issues (and work-around), which explains how libcurl built with IPv6 support may cause trouble on MacOS X 10.5 (Leopard).

According to him, that's because getaddrinfo() causes a SRV lookup to be made and that may be either slow or get discarded completely and thus cause trouble.

This just adds another problem to getaddrinfo() resolves then, since we already have the problem with it when resolving round-robin DNSes since more or less every machine has a bad /etc/gai.conf setup that makes getaddrinfo() return a sorted list instead of the "random" one DNS admins in the wild would prefer the users to use...

aget compared to curl

As you should know, we maintain this curl comparison table on the curl web site, and it lists a set of free tools and how they compare against curl and each other in various aspects. If you want more features compared or other tools included, please tell. Also if you disagree with any of the facts stated there, just shout!cURL

The other day I got an email asking me to add aget to the table, and since it is a free tool (original BSD licensed) with a similar purpose it would indeed fit.

So I downloaded aget 0.4 and had a go at it.

  1. The "stable" 0.4 version doesn't build out of the tarball. It does wrong assumptions on "errno" and thus I had to manually poke on 3 source files to make it generate a fine binary! While this error is claimed to be fixed in the "devel" version, the devel version fails to build on compiler errors instead!
  2. My first test was to download aget's own home page with aget... and it failed. It says the page is 0 bytes and it doesn't download anything and outputs something about a bad seek 0 bytes!
  3. This really turned me off, but then I thought I should report this back to the guys rather than just blog it... but there's no email address in the package that seems suitable, and when checking on the site I find a reference to a mailing list but when trying to read the list's archive it just redirects back to the main page! So blogging it is.
  4. aget 0.4 from 2002, the aget devel version is from June 2004. Development seems to have stopped.
  5. I decided aget isn't going to be added to the table by me at this time. It'll have to mature some more first (and given the age of the tarballs I doubt that'll happen...). I also read through the source code a bit and it really gives the impression of being a young project that hasn't yet have time to settle since there are numerous of suspicious conclusions and source code doing "funny" things.

curl and libcurl 7.17.1

7.17.1 - the 102nd release of curl is out, with less than 5 months left to our ten year anniversary!

The previous release (7.17.0) included a few larger internal changes and unfortunately that had the backside that it brought a whole array of new bugs in, that we now have spent almost two months polishing off.


Apart from the twenty or so bug fixes, a range of new things are introduced as well, including improved NSS support, --proxy-negotiate, --post301 (to make curl act more standards compliant on HTTP 301 responses), --hostpubmd.

libcurl hackers will appreciate CURLOPT_OPENSOCKETFUNCTION and CURLOPT_COPYPOSTFIELDS (the latter a complement to the existing CURLOPT_POSTFIELDS that got broken in 7.17.0 if you posted binary data that contains a zero byte).

7.17.1 contains contributions by at least 16 different people (me not included).

curl references

I amuse myself by occasionally reading up on articles and posts "out there" that talk about curl and libcurl, and I often find interesting snippets and data well worth reading. Here's a few of the ones I've stumbled upon recently:

  1. Tony G wrote a post to a u2 database mailing list and did an indirect praise of curl.
  2. writes about how to build a recent libcurl with visual studio 2005

wget going libcurl?

Micah Cowan is the current maintainer of GNU Wget, and he recently posted a long mail to the wgetA gnu head! mailing list titled "Thoughts on Wget 1.x, 2.0".

Two fun quotes for the curious who don't feel like reading the whole post:

1. On the subject of making wget deal with multiple simultanous connections/requests: The obvious solution to that is to use c-ares, which does exactly that: handle DNS queries asynchronously. Actually, I didn't know this until just now, but c-ares was split off from ares to meet the needs of the curl developers.

2. Following the first reasoning, they can indeed get away with even less work if they base that work on an existing solution: While I've talked about not reinventing the wheel, using existing packages to save us the trouble of having to maintain portable async code, higher-level buffered-IO and network comm code, etc, I've been neglecting one more package choice. There is, after all, already a Free Software package that goes beyond handling asynchronous network operations, to specifically handle asynchronous _web_ operations; I'm speaking, of course, of libcurl. There would seem to be some obvious motivation for simply using libcurl to handle all asynchronous web traffic, and wrapping it with the logic we need to handle retries, recursion, timestamping, traversing, selecting which files to download, etc. Besides async web code, of course, we'd also automatically get support for a number of various protocols (SFTP, for example) that have been requested in Wget.libcurl

I am of course happy to see that the consideration exists - even if this won't go further than just expressed in a mail. I did ventilate this idea to the wget people back in 2001, and even though we're now more than six years down the road since then the situation is now even more clear: libcurl is a much more capable and proven transport layer solution and it supports much more protocols than wget is/does.

Me biased? naaah... 🙂

curl work towards release #102

libcurlThis is a bug fix week in curl land, trying to get everything sorted and fine to be able to release a really fine 7.17.1 release within a week or so. We got some nasty memory-related problems with changed protocols re-using the same easy handle, but it was good that they crept up and I think we're doing good changes now that stabilize curl.

Release date now targeted perhaps around October 28-30.

this week in curl land

It has been another busy week, and this time people brought up a range of stupid and annoying bugs:

libcurl...but also included Patrick Monnerat's cool internal re-arrange to use handler structs for the various protocols.

Upcoming dates to check for:

  • October 14 - Feature freeze for the 7.17.1 release (and I take off for China)
  • October 21 - I come back home from China (to catch up with a million emails)
  • Octobert 27-28 (something) - Probable release date for the 7.17.1 release, assuming that all serious bugs have been fixed by then.

As usual, post curl-related stuff on the mailing lists and not to me personally!