The `CURLINFO_LASTSOCKET` information has been deprecated since
curl version 7.45.0 as it may result in an overflow in the
returned socket on certain systems, most importantly on 64 bit
Windows. Instead, a new call `CURLINFO_ACTIVESOCKET` has been
added which instead returns a `curl_socket_t`, which is always
sufficiently long to store a socket.
As we need to provide backwards compatibility with curl versions
smaller than 7.45.0, alias CURLINFO_ACTIVESOCKET to
CURLINFO_LASTSOCKET on platforms without CURLINFO_ACTIVESOCKET.
We're recently trying to upgrade to the current master of libgit2
in Cargo but we're unfortunately hitting a segfault in one of our
tests. This particular test is just a small smoke test that https
works (e.g. it's configured in libgit2). It attempts to clone
from a URL which simply immediately drops connections after
they're accepted (e.g. terminate abnormally). We expect to see a
standard error from libgit2 but unfortunately we're seeing a
segfault.
This segfault is happening inside of the `wait_for` function of
`curl_stream.c` at the line `FD_SET(fd, &errfd)` because `fd` is
-1. This ends up doing an out-of-bounds array access that faults
the program. I tracked back to where this -1 came from to the
line here (returned by `CURLINFO_LASTSOCKET`) and added a check
to return an error.
When curl uses a proxy, it will only use Basic unless we prompt it to
try to use the most secure on it has available.
This is something which git did recently, and it seems like a good idea.
If the stream claims to support this feature, we can let the transport
set the proxy.
We also set HTTPPROXYTUNNEL option so curl can create a tunnel through
the proxy which lets us create our own TLS session (if needed).
cURL has a mode in which it acts a lot like our streams, providing send
and recv functions and taking care of the TLS and proxy setup for us.
Implement a new stream which uses libcurl instead of raw sockets or the
TLS libraries directly. This version does not support reporting
certificates or proxies yet.
