Was seeing spurious SSL connection aborts using libcurl and
OpenSSL. I tracked it down to uncleared error state on the
OpenSSL error stack - patch attached deals with that.
Rough idea of problem:
Code that uses libcurl calls some library that uses OpenSSL but
don't clear the OpenSSL error stack after an error.
ssluse.c calls SSL_read which eventually gets an EWOULDBLOCK from
the OS. Returns -1 to indicate an error
ssluse.c calls SSL_get_error. First thing, SSL_get_error calls
ERR_get_error to check the OpenSSL error stack, finds an old
error and returns SSL_ERROR_SSL instead of SSL_ERROR_WANT_READ or
SSL_ERROR_WANT_WRITE.
ssluse.c returns an error and aborts the connection
Solution:
Clear the openssl error stack before calling SSL_* operation if
we're going to call SSL_get_error afterwards.
Notes:
This is much more likely to happen with multi because it's easier
to intersperse other calls to the OpenSSL library in the same
thread.
John-Mark Bell filed bug #3000052 that identified a problem (with
an associated patch) with the OpenSSL handshake state machine
when the multi interface is used:
Performing an https request using a curl multi handle and using
select or epoll to wait for events results in a hang. It appears
that the cause is the fix for bug #2958179, which makes
ossl_connect_common unconditionally return from the step 2 loop
when fetching from a multi handle.
When ossl_connect_step2 has completed, it updates
connssl->connecting_state to ssl_connect_3. ossl_connect_common
will then return to the caller, as a multi handle is in
use. Eventually, the client code will call curl_multi_fdset to
obtain an updated fdset to select or epoll on. For https
requests, curl_multi_fdset will cause https_getsock to be called.
https_getsock will only return a socket handle if the
connecting_state is ssl_connect_2_reading or
ssl_connect_2_writing. Therefore, the client will never obtain a
valid fdset, and thus not drive the multi handle, resulting in a
hang.
(http://curl.haxx.se/bug/view.cgi?id=3000052)
FTP(S) use two connections that can be set to different recv and
send functions independently, so by introducing recv+send pairs
in the same manner we already have sockets/connections we can
work with FTPS fine.
This commit fixes the FTPS regression introduced in change d64bd82.
Howard Chu brought the bulk work of this patch that properly
moves out the sending and recving of data to the parts of the
code that are properly responsible for the various ways of doing
so.
Daniel Stenberg assisted with polishing a few bits and fixed some
minor flaws in the original patch.
Another upside of this patch is that we now abuse CURLcodes less
with the "magic" -1 return codes and instead use CURLE_AGAIN more
consistently.
ossl_connect_step3() increments an SSL session handle reference counter on
each call. When sessions are re-used this reference counter may be
incremented many times, but it will be decremented only once when done (by
Curl_ossl_session_free()); and the internal OpenSSL data will not be freed
if this reference count remains positive. When a session is re-used the
reference counter should be corrected by explicitly calling
SSL_SESSION_free() after each consecutive SSL_get1_session() to avoid
introducing a memory leak.
(http://curl.haxx.se/bug/view.cgi?id=2926284)
the client certificate. It also disable the key name test as some engines
can select a private key/cert automatically (When there is only one key
and/or certificate on the hardware device used by the engine)
(http://curl.haxx.se/bug/view.cgi?id=2861587) identifying that libcurl used
the OpenSSL function X509_load_crl_file() wrongly and failed if it would
load a CRL file with more than one certificate within. This is now fixed.
powered libcurl in 7.19.6. If there was a X509v3 Subject Alternative Name
field in the certficate it had to match and so even if non-DNS and non-IP
entry was present it caused the verification to fail.
each test, so that the test suite can now be used to actually test the
verification of cert names etc. This made an error show up in the OpenSSL-
specific code where it would attempt to match the CN field even if a
subjectAltName exists that doesn't match. This is now fixed and verified
in test 311.
and the name length differ in those cases and thus leave the matching function
unmodified from before, as the matching functions never have to bother with
the zero bytes in legitimate cases. Peter Sylvester helped me realize that
this fix is slightly better as it leaves more code unmodified and makes the
detection a bit more obvious in the code.
should introduce an option to disable SNI, but as we're in feature freeze
now I've addressed the obvious bug here (pointed out by Peter Sylvester): we
shouldn't try to enable SNI when SSLv2 or SSLv3 is explicitly selected.
Code for OpenSSL and GnuTLS was fixed. NSS doesn't seem to have a particular
option for SNI, or are we simply not using it?
(http://curl.haxx.se/bug/view.cgi?id=2829955) mentioning the recent SSL cert
verification flaw found and exploited by Moxie Marlinspike. The presentation
he did at Black Hat is available here:
https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike
Apparently at least one CA allowed a subjectAltName or CN that contain a
zero byte, and thus clients that assumed they would never have zero bytes
were exploited to OK a certificate that didn't actually match the site. Like
if the name in the cert was "example.com\0theatualsite.com", libcurl would
happily verify that cert for example.com.
libcurl now better use the length of the extracted name, not assuming it is
zero terminated.
only in some OpenSSL installs - like on Windows) isn't thread-safe and we
agreed that moving it to the global_init() function is a decent way to deal
with this situation.
"you replaced the old SSLeay_add_ssl_algorithms() call
with OpenSSL_add_all_algorithms(), however unlike the name suggests,
the second function is not a superset of the first. When using SSL
both these functions will need to be called in order to offer complete
functionality"
out that OpenSSL-powered libcurl didn't support the SHA-2 digest algorithm,
and provided the solution too: to use OpenSSL_add_all_algorithms() instead
of the older SSLeay_* alternative. OpenSSL_add_all_algorithms was added in
OpenSSL 0.9.5
don't know how they got wrong in the first place, but using this output
format makes it possible to quite easily separate the string into an array
of multiple items.
(http://curl.haxx.se/bug/view.cgi?id=2786255) with a patch, identifying how
libcurl did not deal with SSL session ids properly if the server rejected a
re-use of one. Starting now, it will forget the rejected one and remember
the new. This change was for OpenSSL only, it is likely that other SSL lib
code needs similar fixes.
disable "rfc4507bis session ticket support". rfc4507bis was later turned
into the proper RFC5077 it seems: http://tools.ietf.org/html/rfc5077
The enabled extension concerns the session management. I wonder how often
libcurl stops a connection and then resumes a TLS session. also, sending the
session data is some overhead. .I suggest that you just use your proposed
patch (which explicitly disables TICKET).
If someone writes an application with libcurl and openssl who wants to
enable the feature, one can do this in the SSL callback.
Sharad Gupta brought this to my attention. Peter Sylvester helped me decide
on the proper action.
clarity. This does fix one problem that causes ;type=i FTP URLs
to fail in the Turkish locale when CURLOPT_PROXY_TRANSFER_MODE is
used (test case 561)
Added tests 561 and 1092 through 1094 to test various combinations
of ;type= and ;mode= URLs that could potentially fail in the Turkish
locale.
