Coverity CID 252518. This function is in general far too complicated for
its own good and really should be broken down into several smaller
funcitons instead - but I'm adding this protection here now since it
seems there's a risk the code flow can end up here and dereference a
NULL pointer.

Coverity CID 1241948. dumpeasysrc() would get called with
config->current set to NULL which could be dereferenced by a warnf()
call.

Coverity CID 1241951. The condition 'len >= 0' would always be true at
that point and thus not necessary to check for.

Coverity CID 1241957. Removed the unused argument. As this struct and
pointer now are used only for krb5, there's no need to keep unused
function arguments around.

Coverity CID 1243583. get_url_file_name() cannot fail and return a NULL
file name pointer so skip the check for that - it tricks coverity into
believing it can happen and it then warns later on when we use 'outfile'
without checking for NULL.

Reported-By: Luan Cestari

Option --pinnedpubkey takes a path to a public key in DER format and
only connect if it matches (currently only implemented with OpenSSL).

Provides CURLOPT_PINNEDPUBLICKEY for curl_easy_setopt().

Extract a public RSA key from a website like so:
openssl s_client -connect google.com:443 2>&1 < /dev/null | \
sed -n '/-----BEGIN/,/-----END/p' | openssl x509 -noout -pubkey \
| openssl rsa -pubin -outform DER > google.com.der

Coverity CID 1202837. 'newurl' can in fact be allocated even when
Curl_retry_request() returns failure so free it if need be.

Coverity CID 1243581. 'conn' will never be NULL here, and if it would be
the subsequent statement would dereference it!

Coverity CID 1154198. This NULL check implies that the pointer _can_ be
NULL at this point, which it can't. Thus it is dead code. It tricks
static analyzers to warn about dereferencing the pointer since the code
seems to imply it can be NULL.

Improves it for low-latency cases (like the communication with
localhost)

Coverity CID 1222080.

just a minor code style thing to make the code clearer

First try to fix possible memory leaks, in this case:
Only connssl->ctxt xor onnssl->cred being initialized.

Coverity CID 1061126. 'parse' will always be non-NULL here.

Coverity CID 1061118. Point out that it is on purpose.

Coverity CID 1241950. The pointer is never NULL but it might point to
NULL.

Coverity CID 1241947. Since if sscanf() fails, the previously set value
remains set.

Coverity pointed out several of these.

Coverity CID 982331.

Coverify CID 1157776. Removed a superfluous if() that always evaluated
true (and an else clause that never ran), and then re-indented the
function accordingly.

Coverity CID 1215284. The server name is extracted with
Curl_copy_header_value() and passed in to this function, and
copy_header_value can actually can fail and return NULL.

For private keys, use the first match from: user-specified key file
(if provided), ~/.ssh/id_rsa, ~/.ssh/id_dsa, ./id_rsa, ./id_dsa

Note that the previous code only looked for id_dsa files. id_rsa is
now generally preferred, as it supports larger key sizes.

For public keys, use the user-specified key file, if provided.
Otherwise, try to extract the public key from the private key file.
This means that passing --pubkey is typically no longer required,
and makes the key-handling behavior more like OpenSSH.

Coverity CID 1202836. If the proxy environment variable returned an empty
string, it would be leaked. While an empty string is not really a proxy, other
logic in this function already allows a blank string to be returned so allow
that here to avoid the leak.

Coverity CID 1202837. There's a potential risk that 'newurl' gets
overwritten when it was already pointing to allocated memory.

Coverity CID 1215287. There's a potential risk for a memory leak in
here, and moving the free call to be unconditional seems like a cheap
price to remove the risk.

Coverity CID 1215296. There's a potential risk for a memory leak in
here, and moving the free call to be unconditional seems like a cheap
price to remove the risk.

Coverity detected this. CID 1241954. When Curl_poll() returns a negative value
'mcode' was uninitialized. Pretty harmless since this is debug code only and
would at worst cause an error to _not_ be returned...

and separate the example URLs with newlines

This patch fixes the "SSL3_WRITE_PENDING: bad write retry" error that
sometimes occurs when sending an email over SMTPS with OpenSSL. OpenSSL
appears to require the same pointer on a write that follows a retry
(CURLE_AGAIN) as discussed here:

http://stackoverflow.com/questions/2997218/why-am-i-getting-error1409f07fssl-routinesssl3-write-pending-bad-write-retr

Mostly because we use C strings and they end at a binary zero so we know
we can't open a file name using an embedded binary zero.

Reported-by:  <research@g0blin.co.uk>

The switch to using Curl_expire_latest() in commit cacdc27f was a
mistake and was against the advice even mentioned in that commit. The
comparison in asyn-thread.c:Curl_resolver_is_resolved() makes
Curl_expire() the suitable function to use.

Bug: http://curl.haxx.se/bug/view.cgi?id=1426
Reported-By: graysky