These are problems known to exist at the time of this release. Feel free to join in and help us correct one or more of these! Also be sure to check the changelog of the current development status, as one or more of these problems may have been fixed since this was written! 30. You need to use -g to the command line tool in order to use RFC2732-style IPv6 numerical addresses in URLs. 29. IPv6 URLs with zone ID is not supported. http://www.ietf.org/internet-drafts/draft-fenner-literal-zone-02.txt specifies the use of a plus sign instead of a percent when specifying zone IDs in URLs to get around the problem of percent signs being special. According to the reporter, Firefox deals with the URL _with_ a percent letter (which seems like a blatant URL spec violation). See http://curl.haxx.se/bug/view.cgi?id=1371118 28. The TFTP code is not portable and will fail on some architectures. 26. NTLM authentication using SSPI (on Windows) when (lib)curl is running in "system context" will make it use wrong(?) user name - at least when compared to what winhttp does. See http://curl.haxx.se/bug/view.cgi?id=1281867 25. When doing a CONNECT request with curl it doesn't properly handle if the proxy closes the connection within the authentication "negotiation phase". Like if you do HTTPS or similar over a proxy and you use perhaps --proxy-anyauth. There's work in progress on this problem, and a recent patch was posted here: http://curl.haxx.se/mail/lib-2005-08/0074.html 24. Harshal Pradhan's Use-after-free with libcurl+ares. This probably occurs because there is a pending ares callback that gets called after the connection struct has been freed in libcurl: http://curl.haxx.se/mail/lib-2005-08/0022.html Fixing this properly most likely requires a new c-ares function. 23. We don't support SOCKS for IPv6. We don't support FTPS over a SOCKS proxy. We don't have any test cases for SOCKS proxy. We probably have even more bugs and lack of features when a SOCKS proxy is used. 22. Sending files to a FTP server using curl on VMS, might lead to curl complaining on "unaligned file size" on completion. The problem is related to VMS file structures and the perceived file sizes stat() returns. A possible fix would involve sending a "STRU VMS" command. http://curl.haxx.se/bug/view.cgi?id=1156287 21. FTP ASCII transfers do not follow RFC959. They don't convert the data accordingly (not for sending nor for receiving). RFC 959 section 3.1.1.1 clearly describes how this should be done: The sender converts the data from an internal character representation to the standard 8-bit NVT-ASCII representation (see the Telnet specification). The receiver will convert the data from the standard form to his own internal form. 19. FTP 3rd party transfers with the multi interface doesn't work. Test: define CURL_MULTIEASY, rebuild curl, run test case 230 - 232. 18. test case 57 has that should be but when corrected, the test case fails! 16. FTP URLs passed to curl may contain NUL (0x00) in the RFC 1738 , , and components, encoded as "%00". The problem is that curl_unescape does not detect this, but instead returns a shortened C string. From a strict FTP protocol standpoint, NUL is a valid character within RFC 959 , so the way to handle this correctly in curl would be to use a data structure other than a plain C string, one that can handle embedded NUL characters. From a practical standpoint, most FTP servers would not meaningfully support NUL characters within RFC 959 , anyway (e.g., UNIX pathnames may not contain NUL). 14. Test case 165 might fail on system which has libidn present, but with an old iconv version (2.1.3 is a known bad version), since it doesn't recognize the charset when named ISO8859-1. Changing the name to ISO-8859-1 makes the test pass, but instead makes it fail on Solaris hosts that use its native iconv. 13. curl version 7.12.2 fails on AIX if compiled with --enable-ares. The workaround is to combine --enable-ares with --disable-shared 12. When connecting to a SOCKS proxy, the (connect) timeout is not properly acknowledged after the actual TCP connect (during the SOCKS "negotiate" phase). Pointed out by Lucas. Fix: need to select() and timeout properly. 11. Using configure --disable-[protocol] may cause 'make test' to fail for tests using the disabled protocol(s). 10. To get HTTP Negotiate authentication to work fine, you need to provide a (fake) user name (this concerns both curl and the lib) because the code wrongly only considers authentication if there's a user name provided. http://curl.haxx.se/bug/view.cgi?id=1004841. How? http://curl.haxx.se/mail/lib-2004-08/0182.html 9. --limit-rate using -d or -F does not work. This is because the limit logic is provided by the curl app in its read/write callbacks, and when doing -d/-F the callbacks aren't used! http://curl.haxx.se/bug/view.cgi?id=921395 8. Doing resumed upload over HTTP does not work with '-C -', because curl doesn't do a HEAD first to get the initial size. This needs to be done manually for HTTP PUT resume to work, and then '-C [index]'. 7. CURLOPT_USERPWD and CURLOPT_PROXYUSERPWD have no way of providing user names that contain a colon. This can't be fixed easily in a backwards compatible way without adding new options (and then, they should most probably allow setting user name and password separately). 6. libcurl ignores empty path parts in FTP URLs, whereas RFC1738 states that such parts should be sent to the server as 'CWD ' (without an argument). The only exception to this rule, is that we knowingly break this if the empty part is first in the path, as then we use the double slashes to indicate that the user wants to reach the root dir (this exception SHALL remain even when this bug is fixed). 5. libcurl doesn't treat the content-length of compressed data properly, as it seems HTTP servers send the *uncompressed* length in that header and libcurl thinks of it as the *compressed* length. Some explanations are here: http://curl.haxx.se/mail/lib-2003-06/0146.html 3. GOPHER transfers seem broken 2. If a HTTP server responds to a HEAD request and includes a body (thus violating the RFC2616), curl won't wait to read the response but just stop reading and return back. If a second request (let's assume a GET) is then immediately made to the same server again, the connection will be re-used fine of course, and the second request will be sent off but when the response is to get read, the previous response-body is what curl will read and havoc is what happens. More details on this is found in this libcurl mailing list thread: http://curl.haxx.se/mail/lib-2002-08/0000.html