FAQ
-Problems connecting to SSL servers.
-===================================
+1. Problems connecting to SSL servers.
It took a very long time before I could sort out why curl had problems
to connect to certain SSL servers when using SSLeay or OpenSSL v0.9+.
I have also seen examples where the remote server didn't like the SSLv2
request and instead you had to force curl to use SSLv3 with -3/--sslv3.
-Does curl support resume?
-=========================
+2. curl: (1) SSL is disabled, https: not supported
+
+ If you get this output when trying to get anything from a https:// server,
+ it means that the configure script couldn't find all libs and include files
+ it requires for SSL to work. If the configure script fails to find them,
+ curl is simply built without SSL support.
+
+ To get the https:// support into a curl that was previously built but that
+ reports that https:// is not supported, you should dig through the document
+ and logs and check out why the configure script doesn't find the SSL libs
+ and/or include files.
+
+ Also, check out the other paragraph in this FAQ labeled "configure doesn't
+ find OpenSSL even when it is installed".
+
+3. Does curl support resume?
Yes. Both ways on FTP, download ways on HTTP.
-Is libcurl thread safe?
-=======================
+4. Is libcurl thread safe?
- Yes, as far as curl's own code goes. It does use system calls that often
- aren't thread safe in most environments, such as gethostbyname().
+ As version seven is slowly marching in as the libcurl version to use, we
+ have made a serious attempt to address all places in the code where we could
+ forsee problems for multi-threaded programs. If your system has them, curl
+ will attempt to use threadsafe functions instead of non-safe ones.
I am very interested in once and for all getting some kind of report or
README file from those who have used libcurl in a threaded environment,
since I haven't and I get this question more and more frequently!
-Why doesn't my posting using -F work?
-=====================================
+5. Why doesn't my posting using -F work?
You can't simply use -F or -d at your choice. The web server that will
receive your post assumes one of the formats. If the form you're trying to
use the -F type. In all the most common cases, you should use -d which then
causes a posting with the type 'application/x-www-form-urlencoded'.
-Does curl support custom FTP commands?
-======================================
+ I have described this in some detail in the README.curl file, and if you
+ don't understand it the first time, read it again before you post questions
+ about this to the mailing list. I would also suggest that you read through
+ the mailing list archives for old postings and questions regarding this.
+
+6. Does curl support custom FTP commands?
Yes it does, you can tell curl to perform optional commands both before
and/or after a file transfer. Study the -Q/--quote option.
ftp commands without transfering anything. Therefore you must always specify
a URL to transfer to/from even when doing custom FTP commands.
-Does curl work with other SSL libraries?
-========================================
+7. Does curl work with other SSL libraries?
Curl has been written to use OpenSSL, although I doubt there would be much
problems using a different library. I just don't know any other free one and
If anyone does "port" curl to use a commercial SSL library, I am of course
very interested in getting the patch!
-configre doesn't find OpenSSL even when it is installed
-=======================================================
+8. configure doesn't find OpenSSL even when it is installed
+
+ This may be because of several reasons.
+
+ 8.1. native linker doesn't find openssl
+
+ Platforms: Solaris (native cc compiler) and HPUX (native cc compiler)
+
+ When configuring curl, I specify --with-ssl. OpenSSL is installed in
+ /usr/local/ssl Configure reports SSL in /usr/local/ssl, but fails to find
+ CRYPTO_lock in -lcrypto
+
+ Cause: The cc for this test places the -L/usr/local/ssl/lib AFTER
+ -lcrypto, so ld can't find the library. This is due to a bug in the GNU
+ autoconf tool.
+
+ Workaround: Specifying "LDFLAGS=-L/usr/local/ssl/lib" in front of
+ ./configure places the -L/usr/local/ssl/lib early enough in the command
+ line to make things work
+
+ Submitted by: Bob Allison <allisonb@users.sourceforge.net>
- Platforms: Solaris (native cc compiler) and HPUX (native cc compiler)
+ 8.2. only the libssl lib is missing
- When configuring curl, I specify --with-ssl. OpenSSL is installed in
- /usr/local/ssl Configure reports SSL in /usr/local/ssl, but fails to find
- CRYPTO_lock in -lcrypto
+ If all include files and the libcrypto lib is present, with only the
+ libssl being missing according to configure, this is mostly likely because
+ a few functions are left out from the libssl.
- Cause: The cc for this test places the -L/usr/local/ssl/lib AFTER -lcrypto,
- so ld can't find the library. This is due to a bug in the GNU autoconf tool.
+ If the function names missing include RSA or RSAREF you can be certain
+ that this is because libssl requires the RSA and RSASEF libs to build.
- Workaround: Specifying "LDFLAGS=-L/usr/local/ssl/lib" in front of ./configure
- places the -L/usr/local/ssl/lib early enough in the command line to make
- things work
+ See the INSTALL file section that explains how to add those libs to
+ configure. Make sure that you remove the config.cache file before you
+ rerun configure with the new flags.
- Submitted by: Bob Allison <allisonb@users.sourceforge.net>