This is a continuation of my little top-3 things in curl during 2011 which started with the top-3 changes 2011.
The changelog on the curl site lists 150 bugs fixed in the seven released of the year. The most import fixes in my view were...
Bug-fix 1: handle HTTP redirects to //hostname/path
Following redirects is one of the fundamentals of HTTP user agents and one of the primary things people use curl and libcurl for is to mimic browser to do automatic stuff on the web. Therefore it was even more embarrassing to realize that libcurl didn't properly support the relative redirect when the Location: header doesn't include the protocol but the host name. It basically means that the protocol shall remain (in reality that means HTTP or HTTPS) but it should move over to the new host and path. All browsers support this since ages ago. Since November 15th 2011, libcurl does too!
Bug-fix 2: inappropriate GSSAPI delegation
We had one security vulnerability announced in 2011 and this was it. I won't try to blame someone else for this mistake, but there are some corners of curl and libcurl I'm not personally very familiar with and I would say the GSS stuff is one of those. In fact, even the actual GSS and GSSAPI technologies areÂ mercyÂ areas as far as my knowledge reaches so I was not at all aware of this feature or that we even made us of it... Of course it also turns out that there's a certain amount of existing applications that need it so we now have that ability in the library again if enabled by an option.
Bug-fix 3: multi interface, connect fail continue to next IP
One of those silly bugs nobody would expect us to have at this point. It turned out the code for the multi interface didn't properly move on to try the next IP in case a connect() failed and the host name had resolved to a number of addresses to try. A long term goal of mine is to remodel the internals of libcurl to always use the multi interface code and I would just wrap that interfact with some glue logic to offer the easy interface. For that to work (and for lots of other reasons of course), the multi interface simply must work for all of these things.
Additionally, this is another of those things that are hard to test for in the test suite as it would involve trickery on IP or TCP level and that's not easy to accomplish in a portable manner.