SSL_shutdown() does not like it when we pass an unitialized ssl context
to it. This means that when we fail to connect to a host, we hide the
error message saying so with OpenSSL's indecipherable error message.
Versions prior to 0.9.8f did not have this function, rhel/centos5 are still on a
heavily backported version of 0.9.8e and theoretically supported until March 2017
Without this ifdef, I get the following link failure:
```
CMakeFiles/libgit2_clar.dir/src/openssl_stream.c.o: In function `openssl_connect':
openssl_stream.c:(.text+0x45a): undefined reference to `SSL_set_tlsext_host_name'
collect2: error: ld returned 1 exit status
make[6]: *** [libgit2_clar] Error 1
```
When linking against libcurl, use it as the underlying transport instead
of straight sockets. We can't quite just give over the file descriptor,
as curl puts it into non-blocking mode, so we build a custom BIO so
OpenSSL sends the data through our stream, be it the socket or curl
streams.
This can be used by tools to show mesages about failing to communicate
with the server. The error message in this case will often contain the
server's error message, as far as it managed to send anything.
We use a blocking socket and set the mode to AUTO_RETRY which means that
`SSL_write` and `SSL_read` will only return once the read or write has
been completed. We therefore don't need to handle partial writes or
re-try read due to a regenotiation.
While here, consider that a zero also indicates an error condition.
Windows headers #define some names that openssl uses too. Openssl
headers #undef the offending names before reusing them. But if those
offending Windows headers get included after the openssl headers the
namespace is polluted and nothing good happens.
Fixes issue #2850.
This fixes the build at least on FreeBSD, where those types were not
defined indirectly:
src/openssl_stream.c💯18: error: variable has incomplete type 'struct in6_addr'
struct in6_addr addr6;
^
src/openssl_stream.c💯9: note: forward declaration of 'struct in6_addr'
struct in6_addr addr6;
^
src/openssl_stream.c:111:18: error: use of undeclared identifier 'AF_INET'
if (p_inet_pton(AF_INET, host, &addr4)) {
^
src/unix/posix.h:31:40: note: expanded from macro 'p_inet_pton'
^
src/openssl_stream.c:115:18: error: use of undeclared identifier 'AF_INET6'
if(p_inet_pton(AF_INET6, host, &addr6)) {
^
src/unix/posix.h:31:40: note: expanded from macro 'p_inet_pton'
^
Most of the network-facing facilities have been copied to the socket and
openssl streams. No code now uses these functions directly anymore, so
we can now remove them.
This unfortunately isn't as stackable as could be possible, as it
hard-codes the socket stream. This is because the method of using a
custom openssl BIO is not clear, and we do not need this for now. We can
still bring this in if and as we need it.
