curl 7.65.0 dances in

After another eight week cycle was been completed, curl shipped a new release into the world. 7.65.0 brings some news and some security fixes but is primarily yet again a set of bug-fixes bundled up. Remember 7.64.1?

As always, download it straight from curl.haxx.se!

One fun detail on this release: we have 500 less lines of source code in the lib/ directory compared to the previous release!

Things that happened in curl since last release:

Numbers

the 181st release
3 changes
56 days (total: 7,733)

119 bug fixes (total: 5,148)
215 commits (total: 24,326)
0 new public libcurl function (total: 80)
1 new curl_easy_setopt() option (total: 267)

0 new curl command line option (total: 221)
50 contributors, 24 new (total: 1,953)
32 authors, 12 new (total: 681)
2 security fixes (total: 89)
350 USD paid in Bug Bounties

News

  1. libcurl has deprecated support for the global DNS cache.
  2. Pipelining support is now completely removed from curl.
  3. CURLOPT_MAXAGE_CONN is a new option that controls how long to keep a live connection in the connection cache for reuse.

Security

This release comes with fixes for two separate security problems. Both rated low risk. Both reported via the new bug bounty program.

CVE-2019-5435 is an issue in the recently introduced URL parsing API. It is only a problem in 32 bit architectures and only if an application can be told to pass in ridiculously long (> 2GB) strings to libcurl. This bug is similar in nature to a few other bugs libcurl has had in the past, and to once and for all combat this kind of flaw libcurl now (in 7.65.0 and forward) has a “maximum string length” limit for strings that you can pass to it using its APIs. The maximum size is 8MB. (The reporter was awarded 150 USD for this find.)

CVE-2019-5436 is a problem in the TFTP code. If an application decides to uses a smaller “blksize” than 504 (default is 512), curl would overflow a buffer allocated on the heap with data received from the server. Luckily, very few people actually download data from unknown or even remote TFTP servers. Secondly, asking for a blksize smaller than 512 is rather pointless and also very rare: the primary point in changing that size is to enlarge it. (The reporter was awarded 200 USD for this find.)

Bug-fixes

Over one hundred bug-fixes landed in this release, but some of my favorites from release cycle include…

mark connection for close on TLS close_notify

close_notify is a message in the TLS protocol that means that this connection is about to close. In most circumstances that message doesn’t actually provide information to curl that is needed, but in the case the connection is closed prematurely, understanding that this message preceded the closure helps curl act appropriately. This change was done for the OpenSSL backend only as that’s where we got the bug reported and worked on it this time, but I think we might have reasons to do the same for other backends going forward!

show port in the verbose “Trying …” message

The verbose message that says “Trying 12.34.56.78…” means that curl has sent started a TCP connect attempt to that IP address. This message has now been modified to also include the target port number so when using -v with curl 7.65.0, connecting to that same host for HTTPS will instead say “Trying 12.34.56.78:443…”.

To aid debugging really. I think it gives more information faster at a place you’re already looking.

new SOCKS 4+5 test server

The test suite got a brand new SOCKS server! Previously, all SOCKS tests for both version 4 and version 5 were done by firing up ssh (typically openssh). That method was decent but made it hard to do a range of tests for bad behavior, bad protocol replies and similar. With the new custom test server, we can basically add whatever test we want and we’ve already extended the SOCKS testing to cover more code and use cases than previously.

SOCKS5 user name and passwords must be shorter than 256

curl allows user names and passwords provided in URLs and as separate options to be more or less unrestricted in size and that include if the credentials are used for SOCKS5 authentication – totally ignoring the fact that the protocol SOCKS5 has a maximum size of 255 for the fields. Starting now, curl will return an error if the credentials for SOCKS5 are too long.

Warn if curl and libcurl versions do not match

The command line tool and the library are independent and separable, as in you can run one version of the curl tool with another version of the libcurl library. The libcurl API is solid enough to allow it and the tool is independent enough to not restrict it further.

We always release curl the command line tool and libcurl the library together, using the same version number – with the code for both shipped in the same single file.

There should rarely be a good reason to actually run curl and libcurl with different versions. Starting now, curl will show a little warning if this is detected as we have learned that this is almost always a sign of an installation or setup mistake. Hopefully this message will aid people to detect the mistake earlier and easier.

Better handling of “–no-” prefixed options

curl’s command line parser allows users to switch off boolean options by prefixing them with dash dash no dash. For example we can switch off compressed responses by using “–no-compression” since there regular option “–compression” switches it on.

It turned out we stripped the “–no-” thing no regarding if the option was boolean or not and presumed the logic to handle it – which it didn’t. So users could actually pass a proxy string to curl with the regular option “–proxy” as well as “–no-proxy”. The latter of course not making much sense and was just due to an oversight.

In 7.65.0, only actual boolean command line options can be used with “–no-“. Trying it on other options will cause curl to report error for it.

Add CURLUPART_ZONEID to the URL API

Remember when we added a new URL parsing API to libcurl back in 7.62.0? It wasn’t even a year ago! When we did this, we also changed the internals to use the same code. It turned out we caused a regression when we parsed numerical IPv6 addresses that provide the zone ID within the string. Like this: “https://[ffe80::1%25eth0]/index.html”

Starting in this release, you can both set and get the zone ID in a URL using the API, but of course setting it doesn’t do anything unless the host is a numeric IPv6 address.

parse proxy with the URL parser API

We removed the separate proxy string parsing logic and instead switched that over to more appropriately use the generic URL parser for this purpose as well. This move reduced the code size, made the code simpler and makes sure we have a unified handling of URLs! Everyone is happy!

longer URL schemes

I naively wrote the URL parser to handle scheme names as long as the longest scheme we support in curl: 8 bytes. But since the parser can also be asked to parse URLs with non-supported schemes, that limit was a bit too harsh. I did a quick research, learned that the longest currently registered URI scheme is 36 characters (“microsoft.windows.camera.multipicker”). Starting in this release , curl accepts URL schemes up to 40 bytes long.

Coming up next

There’s several things brewing in the background that might be ready to show in next release. Parallel transfers in the curl tool and deprecating PolarSSL support seem likely to happen for example. Less likely for this release, but still being worked on slowly, is HTTP/3 support.

We’re also likely to get a bunch of changes and fine features we haven’t even thought about from our awesome contributors. In eight weeks I hope to write another one of these blog posts explaining what went into that release…

The curl user survey 2019

the survey

For the 6th consecutive year, the curl project is running a “user survey” to learn more about what people are using curl for, what think think of curl, what the need of curl and what they wish from curl going forward.

the survey

As in most projects, we love to learn more about our users and how to improve. For this, we need your input to guide us where to go next and what to work on going forward.

the survey

Please consider donating a few minutes of your precious time and tell me about your views on curl. How do you use it and what would you like to see us fix?

the survey

The survey will be up for 14 straight days and will be taken down at midnight (CEST) May 26th. We appreciate if you encourage your curl friends to participate in the survey.

Bonus: the analysis from the 2018 survey.

tiny-curl

curl, or libcurl specifically, is probably the world’s most popular and widely used HTTP client side library counting more than six billion installs.

curl is a rock solid and feature-packed library that supports a huge amount of protocols and capabilities that surpass most competitors. But this comes at a cost: it is not the smallest library you can find.

Within a 100K

Instead of being happy with getting told that curl is “too big” for certain use cases, I set a goal for myself: make it possible to build a version of curl that can do HTTPS and fit in 100K (including the wolfSSL TLS library) on a typical 32 bit architecture.

As a comparison, the tiny-curl shared library when built on an x86-64 Linux, is smaller than 25% of the size as the default Debian shipped library is.

FreeRTOS

But let’s not stop there. Users with this kind of strict size requirements are rarely running a full Linux installation or similar OS. If you are sensitive about storage to the exact kilobyte level, you usually run a more slimmed down OS as well – so I decided that my initial tiny-curl effort should be done on FreeRTOS. That’s a fairly popular and free RTOS for the more resource constrained devices.

This port is still rough and I expect us to release follow-up releases soon that improves the FreeRTOS port and ideally also adds support for other popular RTOSes. Which RTOS would you like to support for that isn’t already supported?

Offer the libcurl API for HTTPS on FreeRTOS, within 100 kilobytes.

Maintain API

I strongly believe that the power of having libcurl in your embedded devices is partly powered by the libcurl API. The API that you can use for libcurl on any platform, that’s been around for a very long time and for which you can find numerous examples for on the Internet and in libcurl’s extensive documentation. Maintaining support for the API was of the highest priority.

Patch it

My secondary goal was to patch as clean as possible so that we can upstream patches into the main curl source tree for the changes makes sense and that aren’t disturbing to the general code base, and for the work that we can’t we should be able to rebase on top of the curl code base with as little obstruction as possible going forward.

Keep the HTTPS basics

I just want to do HTTPS GET

That’s the mantra here. My patch disables a lot of protocols and features:

  • No protocols except HTTP(S) are supported
  • HTTP/1 only
  • No cookie support
  • No date parsing
  • No alt-svc
  • No HTTP authentication
  • No DNS-over-HTTPS
  • No .netrc parsing
  • No HTTP multi-part formposts
  • No shuffled DNS support
  • No built-in progress meter

Although they’re all disabled individually so it is still easy to enable one or more of these for specific builds.

Downloads and versions?

Tiny-curl 0.9 is the first shot at this and can be downloaded from wolfSSL. It is based on curl 7.64.1.

Most of the patches in tiny-curl are being upstreamed into curl in the #3844 pull request. I intend to upstream most, if not all, of the tiny-curl work over time.

License

The FreeRTOS port of tiny-curl is licensed GPLv3 and not MIT like the rest of curl. This is an experiment to see how we can do curl work like this in a sustainable way. If you want this under another license, we’re open for business over at wolfSSL!

Sometimes I speak

I view myself as primarily a software developer. Perhaps secondary as someone who’s somewhat knowledgeable in networking and is participating in protocol development and discussions. I do not regularly proclaim myself to be a “speaker” or someone who’s even very good at talking in front of people.

Time to wake up and face reality? I’m slowly starting to realize that I’m actually doing more presentations than ever before in my life and I’m enjoying it.

Since October 2015 I’ve done 53 talks and presentations in front of audiences – in ten countries. That’s one presentation done every 25 days on average. (The start date of this count is a little random but it just happens that I started to keep a proper log then.) I’ve talked to huge audiences and to small. I done presentations that were appreciated and I’ve done some that were less successful.

The room for the JAX keynote, May 2019, as seen from the stage, some 20 minutes before 700 persons sat down in the audience to hear my talk on HTTP/3.

My increased frequency in speaking engagements coincides with me starting to work full-time from home back in 2014. Going to places to speak is one way to get out of the house and see the “real world” a little bit and see what the real people are doing. And a chance to hang out with humans for a change. Besides, I only ever talk on topics that are dear to me and that I know intimately well so I rarely feel pressure when delivering them. 2014 – 2015 was also the time frame when HTTP/2 was being finalized and the general curiosity on that new protocol version helped me find opportunities back then.

Public speaking is like most other things: surprisingly enough, practice actually makes you better at it! I still have a lot to learn and improve, but speaking many times has for example made me better at figuring out roughly how long time I need to deliver a particular talk. It has taught me to “find myself” better when presenting and be more relaxed and the real me – no need to put up a facade of some kind or pretend. People like seeing that there’s a real person there.

I talked HTTP/2 at Techday by Init, in November 2016.

I’m not even getting that terribly nervous before my talks anymore. I used to really get a raised pulse for the first 45 talks or so, but by doing it over and over and over I think the practice has made me more secure and more relaxed in my attitude to the audience and the topics. I think it has made me a slightly better presenter and it certainly makes me enjoy it more.

I’m not “a good presenter”. I can deliver a talk and I can do it with dignity and I think the audience is satisfied with me in most cases, but by watching actual good presenters talk I realize that I still have a long journey ahead of me. Of course, parts of the explanation is that, to connect with the beginning of this post, I’m a developer. I don’t talk for a living and I actually very rarely practice my presentations very much because I don’t feel I can spend that time.

The JAX keynote in May 2019 as seen from the audience. Photo by Bernd Ruecker.

Some of the things that are still difficult include:

The money issue. I actually am a developer and that’s what I do for a living. Taking time off the development to prepare a presentation, travel to a distant place, sacrifice my spare time for one or more days and communicating something interesting to an audience that demands and expects it to be both good and reasonably entertaining takes time away from that development. Getting travel and accommodation compensated is awesome but unfortunately not enough. I need to insist on getting paid for this. I frequently turn down speaking opportunities when they can’t pay me for my time.

Saying no. Oh my god do I have a hard time to do this. This year, I’ve been invited to so many different conferences and the invitations keep flying in. For every single received invitation, I get this warm and comfy feeling and I feel honored and humbled by the fact that someone actually wants me to come to their conference or gathering to talk. There’s the calendar problem: I can’t be in two places at once. Then I also can’t plan events too close to each other in time to avoid them holding up “real work” too much or to become too much of a nuisance to my family. Sometimes there’s also the financial dilemma: if I can’t get compensation, it gets tricky for me to do it, no matter how good the conference seems to be and the noble cause they’re working for.

At SUE 2016 in the Netherlands.

Feedback. To determine what parts of the presentation that should be improved for the next time I speak of the same or similar topic, which parts should be removed and if something should be expanded, figuring what works and what doesn’t work is vital. For most talks I’ve done, there’s been no formal way to provide or receive this feedback, and for the small percentage that had a formal feedback form or a scoring system or similar, taking care of a bunch of distributed grades (for example “your talk was graded 4.2 on a scale between 1 and 5”) and random comments – either positive or negative – is really hard… I get the best feedback from close friends who dare to tell me the truth as it is.

Conforming to silly formats. Slightly different, but some places want me to send me my slides in, either a long time before the event (I’ve had people ask me to provide way over a week(!) before), or they dictate that the slides should be sent to them using Microsoft Powerpoint, PDF or some other silly format. I want to use my own preferred tools when designing presentations as I need to be able to reuse the material for more and future presentations. Sure, I can convert to other formats but that usually ruins formatting and design. Then a lot the time and sweat I put into making a fine and good-looking presentation is more or less discarded! Fortunately, most places let me plug in my laptop and everything is fine!

Upcoming talks?

As a little service to potential audience members and conference organizers, I’m listing all my upcoming speaking engagements on a dedicated page on my web site:

https://daniel.haxx.se/talks.html

I try to keep that page updated to reflect current reality. It also shows that some organizers are forward-planning waaaay in advance…

Here’s me talking about DNS-over-HTTPS at FOSDEM 2019. Photo by Steve Holme.

Invite someone like me to talk?

Here’s some advice on how to invite a speaker (like me) with style:

  1. Ask well in advance (more than 2-3 months preferably, probably not more than 9). When I agree to a talk, others who ask for talks in close proximity to that date will get declined. I get a surprisingly large amount of invitations for events just a month into the future or so, and it rarely works for me to get those into my calendar in that time frame.
  2. Do not assume for-free delivery. I think it is good tone of you to address the price/charge situation, if not in the first contact email at least in the following discussion. If you cannot pay, that’s also useful information to provide early.
  3. If the time or duration of the talk you’d like is “unusual” (ie not 30-60 minutes) do spell that out early on.
  4. Surprisingly often I get invited to talk without a specified topic or title. The inviter then expects me to present that. Since you contact me you clearly had some kind of vision of what a talk by me would entail, it would make my life easier if that vision was conveyed as it could certainly help me produce a talk subject that will work!
Presenting HTTP/2 at the Velocity conference in New York, October 2015, together with Ragnar Lönn.

What I bring

To every presentation I do, I bring my laptop. It has HDMI and USB-C ports. I also carry a HDMI-to-VGA adapter for the few installations that still use the old “projector port”. Places that need something else than those ports tend to have their own converters already since they’re then used with equipment not being fitted for their requirements.

I always bring my own clicker (the “remote” with which I can advance to next slide). I never use the laser-pointer feature, but I like being able to move around on the stage and not have to stand close to the keyboard when I present.

Presentations

I never create my presentations with video or sound in them, and I don’t do presentations that need Internet access. All this to simplify and to reduce the risk of problems.

I work hard on limiting the amount of text on each slide, but I also acknowledge that if a slide set should have value after-the-fact there needs to be a certain amount. I’m a fan of revealing the text or graphics step-by-step on the slides to avoid having half the audience reading ahead on the slide and not listening.

I’ve settled on 16:9 ratio for all presentations. Luckily, the remaining 4:3 projectors are now scarce.

I always make and bring a backup of my presentations in PDF format so that basically “any” computer could display that in case of emergency. Like if my laptop dies. As mentioned above, PDF is not an ideal format, but as a backup it works.

I talked “web transport” in the Mozilla devroom at FOSDEM, February 2017 in front of this audience. Not a single empty seat…

live-streamed curl development

As some of you already found out, I’ve tried live-streaming curl development recently. If you want to catch previous and upcoming episodes subscribe on my twitch page.

Why stream

For the fun of it. I work alone from home most of the time and this is a way for me to interact with others.

To show what’s going on in curl right now. By streaming some of my development I also show what kind of work that’s being done, showing that a lot of development and work are being put into curl and I can share my thoughts and plans with a wider community. Perhaps this will help getting more people to help out or to tickle their imagination.

A screenshot from live stream #11 when parallel transfers with curl was shown off for the first time ever!

For the feedback and interaction. It is immediately notable that one of the biggest reasons I enjoy live-streaming is the chat with the audience and the instant feedback on mistakes I do or thoughts and plans I express. It becomes a back-and-forth and it is not at all just a one-way broadcast. The more my audience interact with me, the more fun I have! That’s also the reason I show the chat within the stream most of the time since parts of what I say and do are reactions and follow-ups to what happens there.

I can only hope I get even more feedback and comments as I get better at this and that people find out about what I’m doing here.

And really, by now I also think of it as a really concentrated and devoted hacking time. I can get a lot of things done during these streaming sessions! I’ll try to keep them going a while.

Twitch

I decided to go with twitch simply because it is an established and known live-streaming platform. I didn’t do any deeper analyses or comparisons, but it seems to work fine for my purposes. I get a stream out with video and sound and people seem to be able to enjoy it.

As of this writing, there are 1645 people following me on twitch. Typical recent live-streams of mine have been watched by over a hundred simultaneous viewers. I also archive all past streams on Youtube, so you can get almost the same experience my watching back issues there.

I announce my upcoming streaming sessions as “events” on Twitch, and I announce them on twitter (@bagder you know). I try to stick to streaming on European day time hours basically because then I’m all alone at home and risk fewer interruptions or distractions from family members or similar.

Challenges

It’s not as easy as it may look trying to write code or debug an issue while at the same time explaining what I do. I learnt that the sessions get better if I have real and meaty issues to deal with or features to add, rather than to just have a few light-weight things to polish.

I also quickly learned that it is better to now not show an actual screen of mine in the stream, but instead I show a crafted set of windows placed on the output to look like it is a screen. This way there’s a much smaller risk that I actually show off private stuff or other content that wasn’t meant for the audience to see. It also makes it easier to show a tidy, consistent and clear “desktop”.

Streaming makes me have to stay focused on the development and prevents me from drifting off and watching cats or reading amusing tweets for a while

Trolls

So far we’ve been spared from the worst kind of behavior and people. We’ve only had some mild weirdos showing up in the chat and nothing that we couldn’t handle.

Equipment and software

I do all development on Linux so things have to work fine on Linux. Luckily, OBS Studio is a fine streaming app. With this, I can setup different “scenes” and I can change between them easily. Some of the scenes I have created are “emacs + term”, “browser” and “coffee break”.

When I want to show off me fiddling with the issues on github, I switch to the “browser” scene that primarily shows a big browser window (and the chat and the webcam in smaller windows).

When I want to show code, I switch to “emacs + term” that instead shows a terminal and an emacs window (and again the chat and the webcam in smaller windows), and so on.

OBS has built-in support for some of the major streaming services, including twitch, so it’s just a matter of pasting in a key in an input field, press ‘start streaming’ and go!

The rest of the software is the stuff I normally use anyway for developing. I don’t fake anything and I don’t make anything up. I use emacs, make, terminals, gdb etc. Everything this runs on my primary desktop Debian Linux machine that has 32GB of ram, an older i7-3770K CPU at 3.50GHz with a dual screen setup. The video of me is captured with a basic Logitech C270 webcam and the sound of my voice and the keyboard is picked up with my Sennheiser PC8 headset.

Some viewers have asked me about my keyboard which you can hear. It is a FUNC-460 that is now approaching 5 years, and I know for a fact that I press nearly 7 million keys per year.

Coffee

In a reddit post about my live-streaming, user ‘digitalsin’ suggested “Maybe don’t slurp RIGHT INTO THE FUCKING MIC”.

How else am I supposed to have my coffee while developing?

This is my home office standard setup. On the left is my video conference laptop and on the right is my regular work laptop. The two screens in the middle are connected to the desktop computer.

What is the incentive for curl to release the library for free?

(This is a repost of the answer I posted on stackoverflow for this question. This answer immediately became my most ever upvoted answer on stackoverflow with 516 upvotes during the 48 hours it was up before a moderator deleted it for unspecified reasons. It had then already been marked “on hold” for being “primarily opinion- based” and then locked but kept: “exists because it has historical significance”. But apparently that wasn’t good enough. I’ve saved a screenshot of the deletion. Debated on meta.stackoverflow.com. Status now: it was brought back but remains locked.)

I’m Daniel Stenberg.

I made curl

I founded the curl project back in 1998, I wrote the initial curl version and I created libcurl. I’ve written more than half of all the 24,000 commits done in the source code repository up to this point in time. I’m still the lead developer of the project. To a large extent, curl is my baby.

I shipped the first version of curl as open source since I wanted to “give back” to the open source world that had given me so much code already. I had used so much open source and I wanted to be as cool as the other open source authors.

Thanks to it being open source, literally thousands of people have been able to help us out over the years and have improved the products, the documentation. the web site and just about every other detail around the project. curl and libcurl would never have become the products that they are today were they not open source. The list of contributors now surpass 1900 names and currently the list grows with a few hundred names per year.

Thanks to curl and libcurl being open source and liberally licensed, they were immediately adopted in numerous products and soon shipped by operating systems and Linux distributions everywhere thus getting a reach beyond imagination.

Thanks to them being “everywhere”, available and liberally licensed they got adopted and used everywhere and by everyone. It created a defacto transfer library standard.

At an estimated six billion installations world wide, we can safely say that curl is the most widely used internet transfer library in the world. It simply would not have gone there had it not been open source. curl runs in billions of mobile phones, a billion Windows 10 installations, in a half a billion games and several hundred million TVs – and more.

Should I have released it with proprietary license instead and charged users for it? It never occured to me, and it wouldn’t have worked because I would never had managed to create this kind of stellar project on my own. And projects and companies wouldn’t have used it.

Why do I still work on curl?

Now, why do I and my fellow curl developers still continue to develop curl and give it away for free to the world?

  1. I can’t speak for my fellow project team members. We all participate in this for our own reasons.
  2. I think it’s still the right thing to do. I’m proud of what we’ve accomplished and I truly want to make the world a better place and I think curl does its little part in this.
  3. There are still bugs to fix and features to add!
  4. curl is free but my time is not. I still have a job and someone still has to pay someone for me to get paid every month so that I can put food on the table for my family. I charge customers and companies to help them with curl. You too can get my help for a fee, which then indirectly helps making sure that curl continues to evolve, remain free and the kick-ass product it is.
  5. curl was my spare time project for twenty years before I started working with it full time. I’ve had great jobs and worked on awesome projects. I’ve been in a position of luxury where I could continue to work on curl on my spare time and keep shipping a quality product for free. My work on curl has given me friends, boosted my career and taken me to places I would not have been at otherwise.
  6. I would not do it differently if I could back and do it again.

Am I proud of what we’ve done?

Yes. So insanely much.

But I’m not satisfied with this and I’m not just leaning back, happy with what we’ve done. I keep working on curl every single day, to improve, to fix bugs, to add features and to make sure curl keeps being the number one file transfer solution for the world even going forward.

We do mistakes along the way. We make the wrong decisions and sometimes we implement things in crazy ways. But to win in the end and to conquer the world is about patience and endurance and constantly going back and reconsidering previous decisions and correcting previous mistakes. To continuously iterate, polish off rough edges and gradually improve over time.

Never give in. Never stop. Fix bugs. Add features. Iterate. To the end of time.

For real?

Yeah. For real.

Do I ever get tired? Is it ever done?

Sure I get tired at times. Working on something every day for over twenty years isn’t a paved downhill road. Sometimes there are obstacles. During times things are rough. Occasionally people are just as ugly and annoying as people can be.

But curl is my life’s project and I have patience. I have thick skin and I don’t give up easily. The tough times pass and most days are awesome. I get to hang out with awesome people and the reward is knowing that my code helps driving the Internet revolution everywhere is an ego boost above normal.

curl will never be “done” and so far I think work on curl is pretty much the most fun I can imagine. Yes, I still think so even after twenty years in the driver’s seat. And as long as I think it’s fun I intend to keep at it.

Why they use curl

As a reader of my blog you know curl. You also most probably already know why you would use curl and if I’m right, you’re also a fan of using the right tool for the job. But do you know why others use curl and why they switch from other solutions to relying on curl for their current and future data transfers? Let me tell you the top reasons I’m told by users.

Logging and exact error handling

What exactly happened in the transfer and why are terribly important questions to some users, and with curl you have the tools to figure that out and also be sure that curl either returns failure or the command worked. This clear and binary distinction is important to users for whom that single file every transfer is important. For example, some of the largest and most well-known banks in the world use curl in their back-ends where each file transfer can mean a transfer of extremely large sums of money.

A few years ago I helped a money transaction service switch to curl to get that exact line in the sand figured out. To know exactly and with certainty if money had been transferred – or not – for a given operation. Vital for their business.

curl does not have the browsers’ lenient approach of “anything goes as long as we get something to show” when it comes to the Internet protocols.

Verbose goodness

curl’s verbose output options allow users to see exactly what curl sends and receives in a quick and non-complicated way. This is invaluable for developers to figure out what’s happening and what’s wrong, in either end involved in the data transfer.

curl’s verbose options allows developers to see all sent and received data even when encryption is used. And if that is not enough, its SSLKEYLOGFILE support allows you to take it to the next level when you need to!

Same behavior over time

Users sometimes upgrade their curl installations after several years of not having done so. Bumping a software’s version after several years and many releases, any software really, can be a bit of a journey and adventure many times as things have changed, behavior is different and things that previously worked no longer do etc.

With curl however, you can upgrade to a version that is a decade newer, with lots of new fancy features and old crummy bugs fixed, only to see that everything that used to work back in the day still works – the same way. With curl, you can be sure that there’s an enormous focus on maintaining old functionality when going forward.

Present on all platforms

The fact that curl is highly portable, our users can have curl and use curl on just about any platform you can think of and use it with the same options and behaviors across them all. Learn curl on one platform, then continue to use it the same way on the next system. Platforms and their individual popularity vary over time and we enjoy to allow users to pick the ones they like – and you can be sure that curl will run on them all.

Performance

When doing the occasional file transfer every once in a while, raw transfer performance doesn’t matter much. Most of the time will then just be waiting on network anyway. You can easily get away with your Python and java frameworks’ multiple levels of overhead and excessive memory consumption.

Users who scan the Internet or otherwise perform many thousands of transfers per second from a large number of threads and machines realize that they need fewer machines that spend less CPU time if they build their file transfer solutions on top of curl. In curl we have a focus on only doing what’s required and it’s a lean and trimmed solution with a well-documented API built purely for Internet data transfers.

The features you want

The author of a banking application recently explained for us that one of the top reasons why they switched to using curl for doing their Internet data transfers, is curl’s ability to keep the file name from the URL.

curl is a feature-packed tool and library that most likely already support the protocols you need and provide the power features you want. With a healthy amount of “extension points” where you can extend it or hook in your custom extra solution.

Support and documentation

No other tool or library for internet transfers have even close to the same amount of documentation, examples available on the net, existing user base that can help out and friendly users to support you when you run into issues. Ask questions on the mailing lists, post a bug on the bug tracker or even show your non-working code on stackoverflow to further your project.

curl is really the only Internet transfer option available to get something that’s old and battle-proven proven by the giants of the industry, that is trustworthy, high-performing and yet for which you can also buy commercial support for, today.

This blog post was also co-posted on wolfssl.com.

curl + hackerone = TRUE

There seems to be no end to updated posts about bug bounties in the curl project these days. Not long ago I mentioned the then new program that sadly enough was cancelled only a few months after its birth.

Now we are back with a new and refreshed bug bounty program! The curl bug bounty program reborn.

This new program, which hopefully will manage to survive a while, is setup in cooperation with the major bug bounty player out there: hackerone.

Basic rules

If you find or suspect a security related issue in curl or libcurl, report it! (and don’t speak about it in public at all until an agreed future date.)

You’re entitled to ask for a bounty for all and every valid and confirmed security problem that wasn’t already reported and that exists in the latest public release.

The curl security team will then assess the report and the problem and will then reward money depending on bug severity and other details.

Where does the money come from?

We intend to use funds and money from wherever we can. The Hackerone Internet Bug Bounty program helps us, donations collected over at opencollective will be used as well as dedicated company sponsorships.

We will of course also greatly appreciate any direct sponsorships from companies for this program. You can help curl getting even better by adding funds to the bounty program and help us reward hard-working researchers.

Why bounties at all?

We compete for the security researchers’ time and attention with other projects, both open and proprietary. The projects that can help put food on these researchers’ tables might have a better chance of getting them to use their tools, time, skills and fingers to find our problems instead of someone else’s.

Finding and disclosing security problems can be very time and resource consuming. We want to make it less likely that people give up their attempts before they find anything. We can help full and part time security engineers sustain their livelihood by paying for the fruits of their labor. At least a little bit.

Only released code?

The state of the code repository in git is not subject for bounties. We need to allow developers to do mistakes and to experiment a little in the git repository, while we expect and want every actual public release to be free from security vulnerabilities.

So yes, the obvious downside with this is that someone could spot an issue in git and decide not to report it since it doesn’t give any money and hope that the flaw will linger around and ship in the release – and then reported it and claim reward money. I think we just have to trust that this will not be a standard practice and if we in fact notice that someone tries to exploit the bounty in this manner, we can consider counter-measures then.

How about money for the patches?

There’s of course always a discussion as to why we should pay anyone for bugs and then why just pay for reported security problems and not for heroes who authored the code in the first place and neither for the good people who write the patches to fix the reported issues. Those are valid questions and we would of course rather pay every contributor a lot of money, but we don’t have the funds for that. And getting funding for this kind of dedicated bug bounties seem to be doable, where as a generic pay contributors fund is trickier both to attract money but it is also really hard to distribute in an open project of curl’s nature.

How much money?

At the start of this program the award amounts are as following. We reward up to this amount of money for vulnerabilities of the following security levels:

Critical: 2,000 USD
High: 1,500 USD
Medium: 1,000 USD
Low: 500 USD

Depending on how things go, how fast we drain the fund and how much companies help us refill, the amounts may change over time.

Found a security flaw?

Report it!

One year in still no visa

One year ago today. On the sunny Tuesday of April 17th 2018 I visited the US embassy in Stockholm Sweden and applied for a visa. I’m still waiting for them to respond.

My days-since-my-visa-application counter page is still counting. Technically speaking, I had already applied but that was the day of the actual physical in-person interview that served as the last formal step in the application process. Most people are then getting their visa application confirmed within weeks.

Initially I emailed them a few times after that interview since the process took so long (little did I know back then), but now I haven’t done it for many months. Their last response assured me that they are “working on it”.

Lots of things have happened in my life since last April. I quit my job at Mozilla and started a new job at wolfSSL, again working for a US based company. One that I cannot go visit.

During this year I missed out on a Mozilla all-hands, I’ve been invited to the US several times to talk at conferences that I had to decline and a friend is getting married there this summer and I can’t go. And more.

Going forward I will miss more interesting meetings and speaking opportunities and I have many friends whom I cannot visit. This is a mild blocker to things I would want to do and it is an obstacle to my profession and career.

I guess I might get my rejection notice before my counter reaches two full years, based on stories I’ve heard from other people in similar situations such as mine. I don’t know yet what I’ll do when it eventually happens. I don’t think there are any rules that prevent me from reapplying, other than the fact that I need to pay more money and I can’t think of any particular reason why they would change their minds just by me trying again. I will probably give it a rest a while first.

I’m lucky and fortunate that people and organizations have adopted to my situation – a situation I of course I share with many others so it’s not uniquely mine – so lots of meetings and events have been held outside of the US at least partially to accommodate me. I’m most grateful for this and I understand that at times it won’t work and I then can’t attend. These days most things are at least partly accessible via video streams etc, repairing the harm a little. (And yes, this is a first-world problem and I’m fortunate that I can still travel to most other parts of the world without much trouble.)

Finally: no, I still have no clue as to why they act like this and I don’t have any hope of ever finding out.


tech, open source and networking