curl/docs/FAQ
2000-05-22 17:35:35 +00:00

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FAQ
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+.
The error sometimes showed up similar to:
16570:error:1407D071:SSL routines:SSL2_READ:bad mac decode:s2_pkt.c:233:
It turned out to be because many older SSL servers don't deal with SSLv3
requests properly. To correct this problem, tell curl to select SSLv2 from
the command line (-2/--sslv2).
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?
=========================
Yes. Both ways on FTP, download ways on HTTP.
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().
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?
=====================================
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
"fake" sets the type to 'multipart/form-data', than and only then you must
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?
======================================
Yes it does, you can tell curl to perform optional commands both before
and/or after a file transfer. Study the -Q/--quote option.
Since curl is used for file transfers, you don't use curl to just perform
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?
========================================
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
that has limited my possibilities to develop against anything else.
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
=======================================================
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>