a0dd9df9ab
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.
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README
Curl is a command line tool for transferring data specified with URL
syntax. Find out how to use curl by reading the curl.1 man page or the
MANUAL document. Find out how to install Curl by reading the INSTALL
document.
libcurl is the library curl is using to do its job. It is readily
available to be used by your software. Read the libcurl.3 man page to
learn how!
You find answers to the most frequent questions we get in the FAQ document.
Study the COPYING file for distribution terms and similar. If you distribute
curl binaries or other binaries that involve libcurl, you might enjoy the
LICENSE-MIXING document.
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If you have problems, questions, ideas or suggestions, please contact us
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All contributors to the project are listed in the THANKS document.
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http://curl.haxx.se/
GIT
To download the very latest source off the GIT server do this:
git clone git://github.com/bagder/curl.git
(you'll get a directory named curl created, filled with the source code)
NOTICE
Curl contains pieces of source code that is Copyright (c) 1998, 1999
Kungliga Tekniska Högskolan. This notice is included here to comply with the
distribution terms.