This release comes but 7 days since the previous and is a patch release only, hence called 7.69.1.

Numbers

the 190th release
0 changes
7 days (total: 8,027)
27 bug fixes (total: 5,938)
48 commits (total: 25,405
0 new public libcurl function (total: 82)
0 new curl_easy_setopt() option (total: 270)
0 new curl command line option (total: 230)
19 contributors, 6 new (total: 2,133)
7 authors, 1 new (total: 772)
0 security fixes (total: 93)
0 USD paid in Bug Bounties

Unplanned patch release

Quite obviously this release was not shipped aligned with our standard 8-week cycle. The reason is that we had too many semi-serious or at least annoying bugs that were reported early on after the 7.69.0 release last week. They made me think our users will appreciate a quick follow-up that addresses them. See below for more details on some of those flaws.

How can this happen in a project that soon is 22 years old, that has thousands of tests, dozens of developers and 70+ CI jobs for every single commit?

The short answer is that we don’t have enough tests that cover enough use cases and transfer scenarios, or put another way: curl and libcurl are very capable tools that can deal with a nearly infinite number of different combinations of protocols, transfers and bytes over the wire. It is really hard to cover all cases.

Also, an old wisdom that we learned already many years ago is that our code is always only properly widely used and tested the moment we do a release and not before. Everything can look good in pre-releases among all the involved developers, but only once the entire world gets its hands on the new release it really gets to show what it can or cannot do.

This time, a few of the changes we had landed for 7.69.0 were not good enough. We then go back, fix issues, land updates and we try again. So here comes 7.69.1 – better patch than sorry!

Bug-fixes

As the numbers above show, we managed to land an amazing number of bug-fixes in this very short time. Here are seven of the more important ones, from my point of view! Not all of them were regressions or even reported in 7.69.0, some of them were just ripe enough to get landed in this release.

unpausing HTTP/2 transfers

When I fixed the pausing and unpausing of HTTP/2 streams for 7.69.0, the fix was inadequate for several of the more advanced use cases and unfortunately we don’t have good enough tests to detect those. At least two browsers built to use libcurl for their HTTP engines reported stalled HTTP/2 transfers due to this.

I reverted the previous change and I’ve landed a different take that seems to be a more appropriate one, based on early reports.

pause: cleanups

After I had modified the curl_easy_pause function for 7.69.0, we also got reports about crashes with uses of this function.

It made me do some additional cleanups to make it more resilient to bad uses from applications, both when called without a correct handle or when it is called to just set the same pause state it is already in

socks: connection regressions

I was so happy with my overhauled SOCKS connection code in 7.69.0 where it was made entirely non-blocking. But again it turned out that our test cases for this weren’t entirely mimicking the real world so both SOCKS4 and SOCKS5 connections where curl does the name resolving could easily break. The test cases probably worked fine there because they always resolve the host name really quick and locally.

SOCKS4 connections are now also forced to be done over IPv4 only, as that was also something that could trigger a funny error – the protocol doesn’t support IPv6, you need to go to SOCKS5 for that!

Both version 4 and 5 of the SOCKS proxy protocol have options to allow the proxy to resolve the server name or you can have the client (curl) do it. (Somewhat described in the CURLOPT_PROXY man page.) These problems were found for the cases when curl resolves the server name.

libssh: MD5 hex comparison

For application users of the libcurl CURLOPT_SSH_HOST_PUBLIC_KEY_MD5 option, which is used to verify that curl connects to the right server, this change makes sure that the libssh backend does the right thing and acts exactly like the libssh2 backend does and how the documentation says it works…

libssh2: known hosts crash

In a recent change, libcurl will try to set a preferred method for the knownhost matching libssh2 provides when connecting to a SSH server, but the code unfortunately contained an easily triggered NULL pointer dereference that no review caught and obviously no test either!

c-ares: duphandle copies DNS servers too

curl_easy_duphandle() duplicates a libcurl easy handle and is frequently used by applications. It turns out we broke a little piece of the function back in 7.63.0 as a few DNS server options haven’t been duplicated properly since then. Fixed now!

curl_version: thread-safer

The curl_version and curl_version_info functions are now both thread-safe without the use of any global context. One issue less left for having a completely thread-safe future curl_global_init.

Schedule for next release

This was an out-of-schedule release but the plan is to stick to the established release schedule, which will have the effect that the coming release window will be one week shorter than usual and the full cycle will complete in 7 weeks instead of 8.

Release video

There has been 56 days since the previous release. As always, download the latest version over at curl.haxx.se.

Perhaps the best news this time is the complete lack of any reported (or fixed) security issues?

Numbers

the 189th release
3 changes
56 days (total: 8,020)
123 bug fixes (total: 5,911)
233 commits (total: 25,357)
0 new public libcurl function (total: 82)
1 new curl_easy_setopt() option (total: 270)
1 new curl command line option (total: 230)
69 contributors, 39 new (total: 2,127)
32 authors, 15 new (total: 771)
0 security fixes (total: 93)
0 USD paid in Bug Bounties

Contributors

Let me first highlight these lovely facts about the community effort that lies behind this curl release!

During the 56 days it took us to produce this particular release, 69 persons contributed to what it is. 39 friends in this crowd were first-time contributors. That’s more than one newcomer every second day. Reporting bugs and providing code or documentation are the primary ways people contribute.

We landed commits authored by 32 individual humans, and out of those 15 were first-time authors! This means that we’ve maintained an average of well over 5 first-time authors per month for the last several years.

The making of curl is a team effort. And we have a huge team!

Changes

In this release cycle we finally removed all traces of support for PolarSSL in the TLS related code. This library doesn’t get updates anymore and has effectively been superseded by its sibling mbedTLS – which we already support since years back. There’s really no reason for anyone to hang on to PolarSSL anymore. Move over to a modern library. wolfSSL, mbedTLS and BearTLS are all similar in spirit and focus. curl now supports 13 different TLS libraries.

We added support for a command line option (--mail-rcpt-allowfails) as well as a libcurl option (CURLOPT_MAIL_RCPT_ALLLOWFAILS) that allows an application to tell libcurl that recipients are fine to fail, as long as at least one is fine. This makes it much easier for applications to send mails to a series of addresses, out of which perhaps a few will fail immediately.

We landed initial support for wolfSSH as a new SSH backend in curl for SFTP transfers.

My top-11 favorite bug-fixes

As usual we’ve landed over a hundred bug-fixes, where most are minor. Here are eleven of the fixes I think stand out a little:

SOCKS connects are now non-blocking

For a very long time we’ve had this outstanding issue that libcurl did the connection phase to SOCKS proxies in a blocking fashion. This of course had unfortunate side-effects if you do many parallel transfers and maybe use slow or remote SOCKS proxies as then each such connection would starve out the others for the duration of the connect handshake.

Now that’s history and libcurl performs SOCKS connection establishment totally non-blocking!

Improved alt-svc parsing

Turns out I had misunderstood the spec a little and the parser needed to be fixed to better deal with some of the real-world Alt-Svc: response headers out there! A fine side effect of more people trying out our early HTTP/3 support, as this is the first major use case of this header in the wild.

Atomic cookie and alt-svc file saves

When saving files to disk, libcurl would previously simply open the file, write all the contents to it and then close it. This caused issues for multi-threaded libcurl users that potentially could start to try to use the saved file before it was done saving, and thus would end up reading partial file. This concerns both cookie and alt-svc usage.

Starting now, libcurl will always save these files into a temporary file with a random suffix while writing data to them, and then when everything is complete, rename the file over to the actual and proper file name. This will make the saving (appear) atomic to all consumers of such files, even in multi-threaded scenarios.

HTTP/2 stream pauses

An application using libcurl to receive a download can tell libcurl to pause the transfer at any given moment. Typically this is used by applications that for some reason consumes the incoming data slowly or has to use small local buffer for it or similar. The transfer is then typically “unpaused” again within shortly and the data can continue flowing in.

When this kind of pause was done for a HTTP/2 stream over a connection that also had other streams going, libcurl previously didn’t actually pause the transfer for real but only “faked” it to the application and instead buffered the incoming data in memory.

In 7.69.0, libcurl will now actually pause HTTP/2 streams for real, even if it might still need to buffer up to a full HTTP/2 window size of data in memory. The HTTP/2 window size is now also reduced to 32MB to at least limit the worst case buffer need to that amount. We might need to come back to this in a future to provide better means for applications to deal with the window size and buffering requirements…

Increased Expect: threshold

Previously, libcurl would add the Expect: header if more than 1024 bytes were sent in the body. Now that limit is raised to 1 MB instead.

HTTP 417 treatment

A 417 HTTP response code from a server when curl has issued a request using the Expect: header means the request should be redone without that header. Starting now, curl does so!

openssl: make CURLINFO_CERTINFO not truncate x509v3 fields

This feature that lets an application extract certificate information from a site curl communicates to had an unfortunate truncating issue that made very long fields occasionally not get returned in full!

smtp: Support UTF-8 based host names

curl SMTP support is now improved when it comes to using IDN names in the URL host name and also in the email addresses provided to some of the SMTP related options and commands.

include: remove non-curl prefixed defines

The public libcurl include files now finally define or provide not a single symbol that isn’t correctly prefixed with either curl or libcurl (in various case versions). This was a cleanup that’s been postponed much too long but a move that should make the headers less likely to ever collide or cause problems in combination with other headers or projects. Keeping within one’s naming scope is important for a good ecosystem citizen.

curl_global_init polish

We made the function assume the EINTR flag by default and we moved away the IPv6 check. Two small parts in an ongoing work to eventually make it thread-safe.

CIFuzz and more Azure jobs

We bumped the number of CI jobs per commit significantly this release cycle, up from 61 to 72.

1. CIFuzz is a great new addition which runs the commit/PR through the OSS-Fuzz fuzzers for a brief time to at verify that it doesn’t at least trigger a problem already then. For now we have that time limit set to 10 minutes.
2. A lot of Marc Hörsken’s Windows builds have been moved over from his more or less custom buildbot setup over to Azure Pipelines.

Next?

File your pull requests. We welcome them!

The year is still young, and we’re here to really kick off 2020 with a brand new curl release! curl 7.68.0 is available at curl.haxx.se as always. Once again we’ve worked hard and pushed through another release cycle to bring you the very best we could do in the 63 days since 7.67.0.

(The previous release was said to be the 186th, but it turned out we’ve been off-by-one on the release counter for a while.)

Numbers

the 188th release
6 changes
63 days (total: 7,964)
124 bug fixes (total: 5,788)
193 commits (total: 25,124)
1 new public libcurl function (total: 82)
0 new curl_easy_setopt() option (total: 269)
3 new curl command line option (total: 229)
70 contributors, 32 new (total: 2,088)
31 authors, 13 new (total: 756)
1 security fixes (total: 93)
400 USD paid in Bug Bounties

Security Vulnerability

CVE-2019-15601: SMB access smuggling via FILE URL on Windows.

Simply put: you could provide a FILE:// URL to curl that could trick it to try to access a host name over SMB – on Windows machines. This could happen because Windows apparently always do this automatically if given the correct file name and curl had no specific filter to avoid it.

For this discovery and report, the curl Bug Bounty program has rewarded Fernando Muñoz 400 USD.

Changes

We ship a new TLS backend: BearSSL. The 14th.

We ship two new command line options for ETags.

We provide a new API call to wakeup “sleeping” libcurl poll calls.

We changed the default handling in libcurl with OpenSSL for verifying certificates. We now allow “partial chains” by default, meaning that you can use an intermediate cert to verify the server cert, not necessarily the whole chain to the root, like you did before. This brings the OpenSSL backend to work more similar to the other TLS backends, and we offer a new option for applications to switch back on the old behavior (CURLSSLOPT_NO_PARTIALCHAIN).

The progress callback has a new feature: if you return CURL_PROGRESSFUNC_CONTINUE from the callback, it will continue and call the internal progress meter.

The new command line option --parallel-immediate is added, and if used will make curl do parallel transfers like before 7.68.0. Starting with 7.68.0, curl will default to defer new connections and rather try to multiplex new transfer over an existing connection if more than one transfer is specified to be done from the same host name.

Bug-fixes

Some of my favorite fixes done since the last release include…

Azure CI and torture

This cycle we started running a bunch of CI tests on Azure Pipelines, both Linux and macOS tests. We also managed to get torture tests running thanks to the new shallow mode.

Azure seem to run faster and more reliable than Travis CI, so moving a few jobs over has made a total build run often complete in less total time now.

prefer multiplexing to using new connections

A regression was found that made the connection reuse logic in libcurl to prefer new connections to multiplexing more than what was actually intended and once fixed we should see libcurl-using application do more and better HTTP/2 multiplexing.

support for ECDSA and ed25519 knownhost keys with libssh2

libssh2 is the primary SSH backend people use with curl. While the library itself has supported these new “knownhost” keys for a while, we hadn’t previously adjusted curl to play nicely with them. Until now.

openssl: Revert to less sensitivity for SYSCALL errors

Another regression in the OpenSSL backend code made curl overly sensitive to some totally benign TLS messages which would cause a curl error when they should just have been silently handled and closed the connection cleanly.

openssl: set X509_V_FLAG_PARTIAL_CHAIN by default

The OpenSSL backend now behaves more similar to other TLS backends in curl and now accepts “partial” certificate chains. That means you don’t need to have the entire chain locally all the way to the root in order to verify a server certificate. Unless you set CURLSSLOPT_NO_PARTIALCHAIN to enforce that behavior.

parsedate: offer a getdate_capped() alternative

The date parser was extended to make curl handle dates beyond 2038 better on 32 bit systems, which primarily seems to happen with cookies. Now the parser understands that they’re too big and will use the max time value it can hold instead of failing and using a zero, as that would make the cookies into “session cookies” which would have slightly different behavior.

Video presenting the release

There has been 56 days since curl 7.66.0 was released. Here comes 7.67.0!

This might not be a release with any significant bells or whistles that will make us recall this date in the future when looking back, but it is still another steady step along the way and thanks to the new things introduced, we still bump the minor version number. Enjoy!

As always, download curl from curl.haxx.se.

If you need excellent commercial support for whatever you do with curl. Contact us at wolfSSL.

Numbers

the 186th release
3 changes
56 days (total: 7,901)
125 bug fixes (total: 5,472)
212 commits (total: 24,931)
1 new public libcurl function (total: 81)
0 new curl_easy_setopt() option (total: 269)
1 new curl command line option (total: 226)
68 contributors, 42 new (total: 2,056)
42 authors, 26 new (total: 744)
0 security fixes (total: 92)
0 USD paid in Bug Bounties

The 3 changes

Disable progress meter

Since virtually forever you’ve been able to tell curl to “shut up” with -s. The long version of that is --silent. Silent makes the curl tool disable the progress meter and all other verbose output.

Starting now, you can use --no-progress-meter, which in a more granular way only disables the progress meter and lets the other verbose outputs remain.

CURLMOPT_MAX_CONCURRENT_STREAMS

When doing HTTP/2 using curl and multiple streams over a single connection, you can now also set the number of parallel streams you’d like to use which will be communicated to the server. The idea is that this option should be possible to use for HTTP/3 as well going forward, but due to the early days there it doesn’t yet.

CURLU_NO_AUTHORITY

This is a new flag that the URL parser API supports. It informs the parser that even if it doesn’t recognize the URL scheme it should still allow it to not have an authority part (like host name).

Bug-fixes

Here are some interesting bug-fixes done for this release. Check out the changelog for the full list.

Winbuild build error

The winbuild setup to build with MSVC with nmake shipped in 7.66.0 with a flaw that made it fail. We had added the vssh directory but not adjusted these builds scripts for that. The fix was of course very simple.

We have since added several winbuild builds to the CI to make sure we catch these kinds of mistakes earlier and better in the future.

FTP: optimized CWD handling

At least two landed bug-fixes make curl avoid issuing superfluous CWD commands (FTP lingo for “cd” or change directory) thereby reducing latency.

HTTP/3

Several fixes improved HTTP/3 handling. It builds on Windows better, the ngtcp2 backend now also behaves correctly on macOS, the build instructions are clearer.

Mimics socketpair on Windows

Thanks to the new socketpair look-alike function, libcurl now provides a socket for the application to wait for even when doing name resolves in the dedicated resolver thread. This makes the Windows code work catch up with the similar change that landed in 7.66.0. This makes it easier for applications to behave correctly during the short time gaps when libcurl resolves a host name and nothing else is happening.

curl with lots of URLs

With the introduction of parallel transfers in 7.66.0, we changed how curl allocated handles and setup transfers ahead of time. This made command lines that for example would use [1-1000000] ranges create a million CURL handles and thus use a lot of memory.

It did in fact break a few existing use cases where people did very large ranges with curl. Starting now, curl will just create enough curl handles ahead of time to allow the maximum amount of parallelism requested and users should yet again be able to specify ranges with many million iterations.

curl -d@ was slow

It was discovered that if you ask curl to post data with -d @filename, that operation was unnecessary slow for large files and was sped up significantly.

DoH fixes

Several corrections were made after some initial fuzzing of the DoH code. A benign buffer overflow, a memory leak and more.

HTTP/2 fixes

We relaxed the :authority push promise checks, fixed two cases where libcurl could “forget” a stream after it had delivered all data and dup’ed HTTP/2 handles could issue dummy PRIORITY frames!

connect with ETIMEDOUT now makes CURLE_OPERATION_TIMEDOUT

When libcurl’s connect attempt fails and errno says ETIMEDOUT it means that the underlying TCP connect attempt timed out. This will now be reflected back in the libcurl API as the timed out error code instead of the previously used CURLE_COULDNT_CONNECT.

One of the use cases for this is curl’s --retry option which now considers this situation to be a timeout and thus will consider it fine to retry…

Parsing URL with fragment and question mark

There was a regression in the URL parser that made it mistreat URLs without a query part but with a question mark in the fragment.

The 180th public curl release is a patch release: 7.64.1. There’s been 49 days since 7.64.0 shipped. The first release since our 21st birthday last week. (Full changelog.)

Numbers

the 180th release
2 changes
49 days (total: 7,677)
116 bug fixes (total: 5,029)
184 commits (total: 24,111)
0 new public libcurl functions (total: 80)
2 new curl_easy_setopt() options (total: 267)
1 new curl command line option (total: 221)
49 contributors, 25 new (total: 1,929)
25 authors, 10 new (total: 669)
0 security fixes (total: 87)

News!

This is a patch release but we still managed to introduce some fun news in this version. We ship brand new alt-svc support which we encourage keen and curious users to enable in their builds and test out. We strongly discourage anyone from using that feature in production as we reserve ourselves the right to change it before removing the EXPERIMENTAL label. As mentioned in the blog post linked above, alt-svc is the official way to bootstrap into HTTP/3 so this is a fundamental stepping stone for supporting that protocol version in a future curl.

We also introduced brand new support for the Amiga-specific TLS backend AmiSSL, which is a port of OpenSSL to that platform.

Bug-fixes

With over a hundred bug-fixes landed in this period there are a lot to choose from, but some of the most most fun and important ones from my point of view include the following.

connection check crash

This was a rather bad regression that occasionally caused crashes when libcurl would scan its connection cache for a live connection to reuse. Most likely to trigger with the Schannel backend.

connection sharing crash

The example source code that uses a shared connection cache among many threads was another crash regression. It turned out a thread could accidentally get hold of a connection already in private use by another thread…

“Expire in…” logs removed

Having the harmless but annoying text there was a mistake to begin with. It was a debug-only line that accidentally was pushed and not discovered in time. It’s history now.

curl -M manual removed

The tutorial-like manual piece that was previously included in the -M (or –manual) built-in command documentation, is no longer included. The output shown is now just the curl.1 man page. The reason for this is that the tutorial has gone a bit stale and there is now better updated and better explained documentation elsewhere. Primarily perhaps in everything curl. The online version of that document will eventually also be removed.

TLS terminology cleanups

We now refer to the Windows TLS backend as “Schannel” and the Apple macOS one as “Secure Transport” in all curl code and documentation. Those are the official names and those are the names people in general know them as. No more use of the former names that sometimes made people confused.

Shaving off bytes and mallocs

We rearranged the layout of a few structs and changed to using bitfields instead of booleans and more. This way, we managed to shrink two of the primary internal structs by 5% and 11% with no functionality change or loss.

Similarly, we removed a few mallocs, even in the common code path, so now the number of allocs for my regular test download of 4GB data over a localhost HTTP server claims fewer allocs than ever before.

Next?

We estimate that there will be a 7.65.0 release to ship 56 days from now. Then we will remove some deprecated features, perhaps add something new and quite surely fix a whole bunch of more bugs. Who know what fun we will come up with at curl up this coming weekend?

Keep reporting. Keep posting pull-requests. We love them and you!