Tag Archives: cURL and libcurl

cURL and libcurl

curlers rest on Sundays and during July

We now run gitstats on the curl git repository daily and provides fun graphs.

We have almost 11 years of source code history covered and I personally have done some ~68% of all commits. Given this long history it is fun to see some very clear trends. Like this first one: look at the distribution of commits per weekday over the entire period. The amount of commits done during weekends are significantly lower than during the work week, and the Sunday amount is clearly even lower than Saturday:

day_of_week

Similarly, we can see how the activity is spread out over calendar months. This shows an obvious correlation to the slower periods in my life, which means that July is vacation times and the numbers show it:

month_of_year

cURL and libcurl, Haxx, Rockbox

I’m interviewed by foss-magasin

foss-magasin

Claes at foss-magasin.se asked a bunch of questions about me, my commitments within the FOSS community and related matters recently over email. This Swedish interview just now went public: Daniel Stenberg cURL, Rockbox och FOSS-Sthlm (dead link).

For my international friends who don’t understand the Swedish: I am quite happy with the questions and being allowed to answer them at this lengths etc, so I am considering doing a full translation of it and posting it at a later date.

cURL and libcurl

A special thank you from Google

5 Comments

Believe me, this kind of seemingly random act of kindness warms up even the most seasoned and cold hacker’s heart. Look at this excerpt from a mail I received:

From: Stephanie T <…@google.com>
Subject: 2 Googlers would like to recognize your hard work on cURL

Hello Daniel,

As you know, we here in Google’s Open Source Programs Office are always interested in learning about new projects and people in the open source community. To that end, we asked our co-workers to help us by nominating people outside of Google that they thought were doing great things in the world of open source. This information helps us determine which organizations to fund and which projects to select for the Google Summer of Code and related programs.

Chris C and John M (Googlers) believe your work on cURL deserves to be recognized. To show our appreciation for this work, we would like to send you a special thank you gift and 2- $175 USD gift codes (totaling $350 USD) to the Google online store so you can pick out tee shirts or other gifts for yourself and loved ones.

[snip]

Thanks a lot!

(The names of the persons in the mail have been shortened by me to reduce their exposure here.)

cURL and libcurl

Apple’s modified CA cert handling and curl

I tweeted about me finding a change in Apple’s version of curl that I haven’t seen any public patch for. Apple otherwise hosts a whole slew of curl patches which they never discuss with us about but still make public and we can see what they did.

I was trying to help out a fellow curl user on IRC (we’re in #curl on freenode, come see us) and he was trying to understand some funny effects of running curl against a HTTPS site and he showed me the output from a “curl -v” log. The verbose log curiously was different than mine (same curl version built by myself on Linux). My conclusion was that something was different in the Apple version.

The users log said:

* About to connect() to host.example.com port 443 (#0)
*   Trying 1.2.3.4... connected
* Connected to host.example.com (1.2.3.4) port 443 (#0)
* SSLv3, TLS handshake, Client hello (1):

… while my command against the same site said:

* About to connect() to host.example.com port 443 (#0)
*   Trying 1.2.3.4... connected
* Connected to host.example.com (1.2.3.4) port 443 (#0)
* successfully set certificate verify locations:
*   CAfile: /etc/ssl/certs/ca-certificates.crt
  CApath: none
* SSLv3, TLS handshake, Client hello (1):

(I’ve bolded the part my output showed that wasn’t in the mac version, the real host name and IP have been changed.)

It seems I was wrong however.

The output above is only shown if libcurl sets the CA cert path to OpenSSL and it seems the Mac version doesn’t. Somehow they get the CA certs loaded to libcurl differently.

So ok, maybe they didn’t modify curl but they certainly changed how curl uses CA certs and they did this by modifying OpenSSL and clearly their version of OpenSSL now defaults to use their CA cert bundle. The end result for me is still the same though: I have no idea how CA certs work with curl on Mac so it leaves me with the unfortunate situation where I can’t help fellow curl users when they have CA cert problems on a Mac.

It also leaves me very curious on what –cacert does exactly on the mac version of curl.

OpenSSL is patched. Apparently it now works so that if the “normal” x509 validation fails, and TrustEvaluationAgent (TEA) is enabled, it will attempt to use the TEA to validate the certificate. The apple source code to read through for this is x509_vfy_apple.c in their patched OpenSSL tree. It is also possible to skip the TEA verification thing in OpenSSL by setting an environment variable, so that we can still have curl on mac act “as default” with a command line like:

$ env OPENSSL_X509_TEA_DISABLE=1 curl https://www.example.com/

Finally: yes, curl is released under an MIT license. They’re perfectly allowed to do whichever of these actions they want. I know this, and I chose the MIT license fully aware that any company can take the code, modify it and never return any changes. I’m not arguing against anyone’s rights to do this with curl.

Thank you, friendly anonymous helper for helping me straighten out my findings!

c-ares, cURL and libcurl, Development, IT Politics, libssh2, Open Source

Three out of one hundred

1 Comment

If I’m not part of the solution, I’m part of the problem and I don’t want to be part of the problem. More specifically, I’m talking about female presence in tech and in particular in open source projects.

3 out of 100I’ve been an open source and free software hacker, contributor and maintainer for almost 20 years. I’m the perfect stereo-type too: a white, hetero, 40+ years old male living in a suburb of a west European city. (I just lack a beard.) I’ve done more than 20,000 commits in public open source code repositories. In the projects I maintain, and have a leading role in, and for the sake of this argument I’ll limit the discussion to curl, libssh2, and c-ares, we’re certainly no better than the ordinary average male-dominated open source projects. We’re basically only men (boys?) talking to other men and virtually all the documentation, design and coding is done by male contributors (to a significant degree).

Sure, we have female contributors in all these projects, but for example in the curl case we have over 850 named contributors and while I’m certainly not sure who is a woman and who is not when I get contributions, there’s only like 10 names in the list that are typically western female names. Let’s say there are 20. or 30. Out of a total of 850 the proportions are devastating no matter what. It might be up to 3%. Three. THREE. I know women are under-represented in technology in general and in open source in particular, but I think 3% is even lower than the already low bad average open source number. (Although, some reports claim the number of female developers in foss is as low as just above 1%, geekfeminism says 1-5%).

Numbers

Three percent. (In a project that’s been alive and kicking for thirteen years…) At this level after this long time, there’s already a bad precedent and it of course doesn’t make it easier to change now. It is also three percent of the contributors when we consider all contributors alike. If we’d count the number of female persons in leading roles in these projects, the amount would be even less.

It could be worth noting that we don’t really have any recent reliable stats for “real world” female share either. Most sources that I find on the Internet and people have quoted in talks tend to repeat old numbers that were extracted using debatable means and questions. The comparisons I’ve seen repeated many times on female participation in FOSS vs commercial software, are very often based on stats that are really not comparable. If someone has reliable and somewhat fresh data, please point them out for me!

“Ghosh, R. A.; Glott, R.; Krieger, B.;
Robles, G. 2002. Free/Libre and Open Source Software: Survey and Study. Part
IV: Survey of Developers. Maastricht: International Institute of Infonomics
/Merit.

A design problem of “the system”

I would blame “the system”. I’m working in embedded systems professionally as a consultant and contract developer. I’ve worked as a professional developer for some 20 years. In my niche, there’s not even 10% female developers. A while ago I went through my past assignments in order to find the last female developer that I’ve worked with, in a project, physically located in the same office. The last time I met a fellow developer at work who was female was early 2007. I’ve worked in 17 (seventeen!) projects since then, without even once having had a single female developer colleague. I usually work in smaller projects with like 5-10 people. So one female in 18 projects makes it something like one out of 130 or so. I’m not saying this is a number that is anything to draw any conclusions from since it just me and my guesstimates. It does however hint that the problem is far beyond “just” FOSS. It is a tech problem. Engineering? Software? Embedded software? Software development? I don’t know, but I know it is present both in my professional life as well as in my volunteer open source work.

Geekfeminism says the share is 10-30% in the “tech industry”. My experience says the share gets smaller and smaller the closer to “the metal” and low level programming you get – but I don’t have any explanation for it.

Fixing the problems

What are we (I) doing wrong? Am I at fault? Is the the way I talk or the way we run these projects in some subtle – or obvious – ways not friendly enough or downright hostile to women? What can or should we change in these projects to make us less hostile? The sad reality is that I don’t think we have any such fatal flaws in our projects that create the obstacles. I don’t think many females ever show up near enough the projects to even get mistreated in the first place.

I have a son and I have a daughter – they’re both still young and unaware of this kind of differences and problems. I hope I will be able to motivate and push and raise them equally. I don’t want to live in a world where my daughter will have a hard time to get into tech just because she’s a girl.

cURL and libcurl, Network

libspdy

8 Comments

SPDY is a neat new protocol and possible contender to replace HTTP – at least in some areas and for some use cases. SPDY has been invented and developed mostly by Google engineers.

SPDY allows better usage of fewer TCP connections (since it sends multiple logical streams over a single physical TCP connection) and it helps clients overcome problems with TCP (like how a new connection starts slowly) while at the same time reducing latency and bandwidth requirements. Very similar to how channels are handled over an SSH connection.SPDY

Chrome of course already supports SPDY and Firefox has some early experimental support being worked on.

Of course there are also legitimate criticisms against SPDY as well, including subjects like how it makes caching proxies impossible (because everything goes over SSL), how it makes debugging a lot harder by using compressed headers, how it is impossible to extract just a single header from the stream due to its compression approach and how the compression state buffers make each individual stream use more memory than plain old HTTP (plain TCP) ones.

We can expect SPDY<=>HTTP gateways to appear so that nobody gets locked into either side of these protocols.

SPDY will provide faster transfers. libcurl is currently used for speed reasons in many cases. To me, it makes perfect sense to have libcurl use and try to use SPDY instead of HTTP exactly like how the browsers are starting to do it, so that the libcurl using applications will get their contents transferred faster.

My thinking is that we introduce some new magic option(s) that makes libcurl use SPDY, and for normal easy interface transfers it will remain to use a single connection for each new SPDY transfer, but if you use the multi interface and you enable pipelining you’ll instead make libcurl do multiple transfers over the same single SPDY connection (as long as you speak with the same server and port etc). From an application’s stand-point it shouldn’t make any difference, apart from being faster than otherwise. Just like we want it!

Implementation wise, I would like to use a reliable and efficient third-party library for the actual SPDY implementation. If there doesn’t exist any, we make one and run that one independently. I found libspdy, but I found some concerns about it (no mailing list, looks like one-man project, not C89 compliant, no API docs etc). I mailed the libspdy author, I hoping we’d sort out my doubts and then I’d base my continued work on that library.

After some time Thomas Roth, primary libspdy author, responded and during our subsequent email exchange I’ve gotten a restored faith and belief in this library and its direction. Not only did he fix the C89 compliance pretty quickly, he is also promising rather big changes that are pending to get committed within a week or so.

Comforted by what I’ve learned from Thomas, I’ll wait for his upcoming changes and I’ll join the soon to be created mailing list for the libspdy project and I’ll contribute some ideas and efforts to help shape it into the fine SPDY library we all want. I can only encourage other fellow SPDY library interested persons to do the same!

Updated: Join the SPDY library development

cURL and libcurl, Development

curl meetup at Fosdem 2012

The FOSDEM 2012 dates were recently revealed (4-5 February 2012).

A pint of guinness

I’d be happy to arrange a get-together for libcurl hackers at Fosdem this year. To me, Brussels, Belgium seems mid-europe enough to be able to attract a bunch of us:

  • libcurl application users/authors
  • libcurl binding hackers
  • libcurl contributors
  • … and everyone else who’s doing related activities or who just is interested

Potential subjects to discuss at such a meeting:

  • what’s the most important stuff libcurl still lacks?
  • what’s the least documented/understood parts of libcurl?
  • are there shared problems several/many libcurl bindings have to solve?
  • can we improve how we work/develop libcurl and bindings?
  • what kind of beer is best at a curl meetup?
  • [fill in your own curl related subject]

I would like at least 4-5 people voicing interest for this to be worthwhile for me to actually try to do anything. Please speak up on the libcurl mailing list, tweet me or mail me privately! The more people that are interested, the more planning and stuff we’ll do for it.

cURL and libcurl

curl 7.22.0

Another release of curl and libcurl just happened. 7.22.0 is released.

Apart from the 28 something documented bug fixes, we introduce a range of changes that could be noteworthy:

  • Added CURLOPT_GSSAPI_DELEGATION – remember that we explicitly disabled GSSAPI delegation in our previous release due to a security problem. Now we introduce an option for the application to control exactly how to behave.
  • Added support for NTLM delegation to Samba’s winbind daemon helper ntlm_auth. This lets libcurl use the external helper program to do things like NTLM single-sign on.
  • Display notes from setup file in testcurl.pl – provides a way for test clients to provide more information back to the centralized test summary on the primary server.
  • BSD-style lwIP TCP/IP stack experimental support on Windows – there are still flaws in lwIP on windows that prevents it from working properly
  • OpenSSL: Use SSL_MODE_RELEASE_BUFFERS if available – this is basically a way to ask OpenSSL to use less memory
  • –delegation was added to set CURLOPT_GSSAPI_DELEGATION – simply the new option exported to the command line tool
  • nss: start with no database if the selected database is broken – a slightly modified behavior
  • telnet: allow programatic use on Windows – basically making the windows implementation in sync with how the non-windows version already has worked for quite some time

This release is this great thanks to 25 friendly contributors.

cURL

cURL and libcurl

A libcurl postergirl?

1 Comment

google for libcurl

If you click the image you’ll see a full-resolution screendump for my recent search for “libcurl” on google. Where did that (image of a) girl come from? Judging from where it appears on the results page right next to the information about the cURL project you can’t but assume that she’s somehow related to the project.

That’s of course not true. When moving the mouse over the image I get a tooltip with a funny “hair curling” URL and that’s also where a click on the image takes me.

A mighty weird way of presenting a search result if you ask me!

Mail

Remove your software

Your software needs to be removed from my work computer. I did not install it,
do not want it and did not request it.

Another one of those emails arrived in my inbox today:

Subject: Remove:

Your software needs to be removed from my work computer. I did not install it, do not want it and did not request it.

[name redacted]

No mention what software or indication of what platform or what might’ve happened when my software allegedly ended up in the person’s computer. Not very friendly either.

Again I suspect that there’s some software that uses curl in some way, but I can’t tell for sure…

I replied to it, saying that I didn’t install anything on his computer.