1.2 More data sharing
1.3 struct lifreq
1.4 signal-based resolver timeouts
1.5 get rid of PATH_MAX
1.6 progress callback without doubles
1.7 Happy Eyeball dual stack connect

libcurl - multi interface

2.1 More non-blocking
2.2 Remove easy interface internally
2.4 Fix HTTP Pipelining for PUT

Documentation

3.1 More and better

FTP

4.1 HOST
4.2 Alter passive/active on failure and retry
4.3 Earlier bad letter detection
4.4 REST for large files
4.5 FTP proxy support
4.6 ASCII support

HTTP

5.1 Better persistency for HTTP 1.0
5.2 support FF3 sqlite cookie files
5.3 Rearrange request header order

TELNET

6.1 ditch stdin
6.2 ditch telnet-specific select
6.3 feature negotiation debug data
6.4 send data in chunks

SSL

7.1 Disable specific versions
7.2 Provide mutex locking API
7.3 Evaluate SSL patches
7.4 Cache OpenSSL contexts
7.5 Export session ids
7.6 Provide callback for cert verification
7.7 Support other SSL libraries
7.9 improve configure --with-ssl

GnuTLS

8.1 SSL engine stuff
8.3 check connection
8.4 non-gcrypt

New protocols

10.1 RSYNC

Client

11.1 sync
11.2 glob posts
11.3 prevent file overwriting
11.4 simultaneous parallel transfers
11.5 provide formpost headers
11.6 url-specific options
11.7 metalink support
11.8 warning when setting an option
11.9 IPv6 addresses with globbing

Build

12.1 roffit

Test suite

13.1 SSL tunnel
13.2 nicer lacking perl message
13.3 more protocols supported
13.4 more platforms supported

Next SONAME bump

14.1 http-style HEAD output for ftp
14.2 combine error codes
14.3 extend CURLOPT_SOCKOPTFUNCTION prototype

Next major release

15.1 cleanup return codes
15.2 remove obsolete defines
15.3 size_t
15.4 remove several functions
15.5 remove CURLOPT_FAILONERROR
15.6 remove CURLOPT_DNS_USE_GLOBAL_CACHE
15.7 remove progress meter from libcurl
15.8 remove 'curl_httppost' from public
15.9 have form functions use CURL handle argument

1. libcurl

1.2 More data sharing

curl_share_/ functions already exist and work, and they can be extended to share more. For example, enable sharing of the ares channel and the connection cache.

1.3 struct lifreq

Use 'struct lifreq' and SIOCGLIFADDR instead of 'struct ifreq' and SIOCGIFADDR on newer Solaris versions as they claim the latter is obsolete. To support ipv6 interface addresses for network interfaces properly.

1.4 signal-based resolver timeouts

libcurl built without an asynchronous resolver library uses alarm() to time out DNS lookups. When a timeout occurs, this causes libcurl to jump from the signal handler back into the library with a sigsetjmp, which effectively causes libcurl to continue running within the signal handler. This is non-portable and could cause problems on some platforms. A discussion on the problem is available at http://curl.haxx.se/mail/lib-2008-09/0197.html

Also, alarm() provides timeout resolution only to the nearest second. alarm ought to be replaced by setitimer on systems that support it.

1.5 get rid of PATH_MAX

Having code use and rely on PATH_MAX is not nice: http://insanecoding.blogspot.com/2007/11/pathmax-simply-isnt.html

Currently the SSH based code uses it a bit, but to remove PATH_MAX from there we need libssh2 to properly tell us when we pass in a too small buffer and its current API (as of libssh2 1.2.7) doesn't.

1.6 progress callback without doubles

The progress callback was introduced way back in the days and the choice to use doubles in the arguments was possibly good at the time. Today the doubles only confuse users and make the amounts less precise. We should introduce another progress callback option that take precedence over the old one and have both co-exist for a forseeable time until we can remove the double-using one.

1.7 Happy Eyeball dual stack connect

In order to make alternative technologies not suffer when transitioning, like when introducing IPv6 as an alternative to IPv4 and there are more than one option existing simultaneously there are reasons to reconsider internal choices.

To make libcurl do blazing fast IPv6 in a dual-stack configuration, this needs to be addressed:

http://tools.ietf.org/html/draft-ietf-v6ops-happy-eyeballs-07

2. libcurl - multi interface

2.1 More non-blocking

Make sure we don't ever loop because of non-blocking sockets returning EWOULDBLOCK or similar. Blocking cases include:

- Name resolves on non-windows unless c-ares is used - NSS SSL connections - HTTP proxy CONNECT operations - SOCKS proxy handshakes - file:// transfers - TELNET transfers - The "DONE" operation (post transfer protocol-specific actions) for the
protocols SFTP, SMTP, FTP. Fixing Curl_done() for this is a worthy task.

2.2 Remove easy interface internally

Make curl_easy_perform() a wrapper-function that simply creates a multi handle, adds the easy handle to it, runs curl_multi_perform() until the transfer is done, then detach the easy handle, destroy the multi handle and return the easy handle's return code. This will thus make everything internally use and assume the multi interface. The select()-loop should use curl_multi_socket().

2.4 Fix HTTP Pipelining for PUT

HTTP Pipelining can be a way to greatly enhance performance for multiple serial requests and currently libcurl only supports that for HEAD and GET requests but it should also be possible for PUT.

3. Documentation

3.1 More and better

Exactly

4. FTP

4.1 HOST

HOST is a suggested command in the works for a client to tell which host name to use, to offer FTP servers named-based virtual hosting:

http://tools.ietf.org/html/draft-hethmon-mcmurray-ftp-hosts-11

4.2 Alter passive/active on failure and retry

When trying to connect passively to a server which only supports active connections, libcurl returns CURLE_FTP_WEIRD_PASV_REPLY and closes the connection. There could be a way to fallback to an active connection (and vice versa). http://curl.haxx.se/bug/feature.cgi?id=1754793

4.3 Earlier bad letter detection

Make the detection of (bad) 0 and %0a codes in FTP url parts earlier in the process to avoid doing a resolve and connect in vain.

4.4 REST for large files

REST fix for servers not behaving well on >2GB requests. This should fail if the server doesn't set the pointer to the requested index. The tricky (impossible?) part is to figure out if the server did the right thing or not.

4.5 FTP proxy support

Support the most common FTP proxies, Philip Newton provided a list allegedly from ncftp. This is not a subject without debate, and is probably not really suitable for libcurl. http://curl.haxx.se/mail/archive-2003-04/0126.html

4.6 ASCII support

FTP ASCII transfers do not follow RFC959. They don't convert the data accordingly.

5. HTTP

5.1 Better persistency for HTTP 1.0

"Better" support for persistent connections over HTTP 1.0 http://curl.haxx.se/bug/feature.cgi?id=1089001

5.2 support FF3 sqlite cookie files

Firefox 3 is changing from its former format to a a sqlite database instead. We should consider how (lib)curl can/should support this. http://curl.haxx.se/bug/feature.cgi?id=1871388

5.3 Rearrange request header order

Server implementors often make an effort to detect browser and to reject clients it can detect to not match. One of the last details we cannot yet control in libcurl's HTTP requests, which also can be exploited to detect that libcurl is in fact used even when it tries to impersonate a browser, is the order of the request headers. I propose that we introduce a new option in which you give headers a value, and then when the HTTP request is built it sorts the headers based on that number. We could then have internally created headers use a default value so only headers that need to be moved have to be specified.

6. TELNET

6.1 ditch stdin

Reading input (to send to the remote server) on stdin is a crappy solution for library purposes. We need to invent a good way for the application to be able to provide the data to send.

6.2 ditch telnet-specific select

Move the telnet support's network select() loop go away and merge the code into the main transfer loop. Until this is done, the multi interface won't work for telnet.

6.3 feature negotiation debug data

Add telnet feature negotiation data to the debug callback as header data.

6.4 send data in chunks

Currently, telnet sends data one byte at a time. This is fine for interactive use, but inefficient for any other. Sent data should be sent in larger chunks.

7. SSL

7.1 Disable specific versions

Provide an option that allows for disabling specific SSL versions, such as SSLv2 http://curl.haxx.se/bug/feature.cgi?id=1767276

7.2 Provide mutex locking API

Provide a libcurl API for setting mutex callbacks in the underlying SSL library, so that the same application code can use mutex-locking independently of OpenSSL or GnutTLS being used.

7.3 Evaluate SSL patches

Evaluate/apply Gertjan van Wingerde's SSL patches: http://curl.haxx.se/mail/lib-2004-03/0087.html

7.4 Cache OpenSSL contexts

"Look at SSL cafile - quick traces look to me like these are done on every request as well, when they should only be necessary once per ssl context (or once per handle)". The major improvement we can rather easily do is to make sure we don't create and kill a new SSL "context" for every request, but instead make one for every connection and re-use that SSL context in the same style connections are re-used. It will make us use slightly more memory but it will libcurl do less creations and deletions of SSL contexts.

7.5 Export session ids

Add an interface to libcurl that enables "session IDs" to get exported/imported. Cris Bailiff said: "OpenSSL has functions which can serialise the current SSL state to a buffer of your choice, and recover/reset the state from such a buffer at a later date - this is used by mod_ssl for apache to implement and SSL session ID cache".

7.6 Provide callback for cert verification

OpenSSL supports a callback for customised verification of the peer certificate, but this doesn't seem to be exposed in the libcurl APIs. Could it be? There's so much that could be done if it were!

7.7 Support other SSL libraries

Make curl's SSL layer capable of using other free SSL libraries. Such as MatrixSSL (http://www.matrixssl.org/).

7.9 improve configure --with-ssl

make the configure --with-ssl option first check for OpenSSL, then GnuTLS, then NSS...

8. GnuTLS

8.1 SSL engine stuff

Is this even possible?

8.3 check connection

Add a way to check if the connection seems to be alive, to correspond to the SSL_peak() way we use with OpenSSL.

8.4 non-gcrypt

libcurl assumes that there are gcrypt functions available when GnuTLS is.

GnuTLS can be built to use libnettle instead as crypto library, which breaks the previously mentioned assumption

The correct fix would be to detect which crypto layer that is in use and adapt our code to use that instead of blindly assuming gcrypt.

9. Other protocols

10. New protocols

10.1 RSYNC

There's no RFC for protocol nor URI/URL format. An implementation should most probably use an existing rsync library, such as librsync.

11. Client

11.1 sync

"curl --sync http://example.com/feed[1-100].rss" or "curl --sync http://example.net/{index,calendar,history}.html"

Downloads a range or set of URLs using the remote name, but only if the remote file is newer than the local file. A Last-Modified HTTP date header should also be used to set the mod date on the downloaded file.

11.2 glob posts

Globbing support for -d and -F, as in 'curl -d "name=foo[0-9]" URL'. This is easily scripted though.

11.3 prevent file overwriting

Add an option that prevents cURL from overwriting existing local files. When used, and there already is an existing file with the target file name (either -O or -o), a number should be appended (and increased if already existing). So that index.html becomes first index.html.1 and then index.html.2 etc.

11.4 simultaneous parallel transfers

The client could be told to use maximum N simultaneous parallel transfers and then just make sure that happens. It should of course not make more than one connection to the same remote host. This would require the client to use the multi interface. http://curl.haxx.se/bug/feature.cgi?id=1558595

11.5 provide formpost headers

Extending the capabilities of the multipart formposting. How about leaving the ';type=foo' syntax as it is and adding an extra tag (headers) which works like this: curl -F "coolfiles=@fil1.txt;headers=@fil1.hdr" where fil1.hdr contains extra headers like

Content-Type: text/plain; charset=KOI8-R" Content-Transfer-Encoding: base64 X-User-Comment: Please don't use browser specific HTML code

which should overwrite the program reasonable defaults (plain/text, 8bit...)

11.6 url-specific options

Provide a way to make options bound to a specific URL among several on the command line. Possibly by letting ':' separate options between URLs, similar to this:

curl --data foo --url url.com :

        --url url2.com :         --url url3.com --data foo3

(More details: http://curl.haxx.se/mail/archive-2004-07/0133.html)

The example would do a POST-GET-POST combination on a single command line.

11.7 metalink support

Add metalink support to curl (http://www.metalinker.org/). This is most useful with simultaneous parallel transfers (11.6) but not necessary.

11.8 warning when setting an option

Display a warning when libcurl returns an error when setting an option. This can be useful to tell when support for a particular feature hasn't been compiled into the library.

11.9 IPv6 addresses with globbing

Currently the command line client needs to get url globbing disabled (with -g) for it to support IPv6 numerical addresses. This is a rather silly flaw that should be corrected. It probably involves a smarter detection of the '[' and ']' letters.

12. Build

12.1 roffit

Consider extending 'roffit' to produce decent ASCII output, and use that instead of (g)nroff when building src/hugehelp.c

13. Test suite

13.1 SSL tunnel

Make our own version of stunnel for simple port forwarding to enable HTTPS and FTP-SSL tests without the stunnel dependency, and it could allow us to provide test tools built with either OpenSSL or GnuTLS

13.2 nicer lacking perl message

If perl wasn't found by the configure script, don't attempt to run the tests but explain something nice why it doesn't.

13.3 more protocols supported

Extend the test suite to include more protocols. The telnet could just do ftp or http operations (for which we have test servers).

13.4 more platforms supported

Make the test suite work on more platforms. OpenBSD and Mac OS. Remove fork()s and it should become even more portable.

14. Next SONAME bump

14.1 http-style HEAD output for ftp

#undef CURL_FTP_HTTPSTYLE_HEAD in lib/ftp.c to remove the HTTP-style headers from being output in NOBODY requests over ftp

14.2 combine error codes

Combine some of the error codes to remove duplicates. The original numbering should not be changed, and the old identifiers would be macroed to the new ones in an CURL_NO_OLDIES section to help with backward compatibility.

Candidates for removal and their replacements:

CURLE_FILE_COULDNT_READ_FILE => CURLE_REMOTE_FILE_NOT_FOUND CURLE_FTP_COULDNT_RETR_FILE => CURLE_REMOTE_FILE_NOT_FOUND CURLE_FTP_COULDNT_USE_REST => CURLE_RANGE_ERROR CURLE_FUNCTION_NOT_FOUND => CURLE_FAILED_INIT CURLE_LDAP_INVALID_URL => CURLE_URL_MALFORMAT CURLE_TFTP_NOSUCHUSER => CURLE_TFTP_ILLEGAL CURLE_TFTP_NOTFOUND => CURLE_REMOTE_FILE_NOT_FOUND CURLE_TFTP_PERM => CURLE_REMOTE_ACCESS_DENIED

14.3 extend CURLOPT_SOCKOPTFUNCTION prototype

The current prototype only provides 'purpose' that tells what the connection/socket is for, but not any protocol or similar. It makes it hard for applications to differentiate on TCP vs UDP and even HTTP vs FTP and similar.

15. Next major release

15.1 cleanup return codes

curl_easy_cleanup() returns void, but curl_multi_cleanup() returns a CURLMcode. These should be changed to be the same.

15.2 remove obsolete defines

remove obsolete defines from curl/curl.h

15.3 size_t

make several functions use size_t instead of int in their APIs

15.4 remove several functions

remove the following functions from the public API:
curl_getenv

curl_mprintf (and variations)

curl_strequal

curl_strnequal

They will instead become curlx_ - alternatives. That makes the curl app still capable of using them, by building with them from source.

These functions have no purpose anymore:

curl_multi_socket

curl_multi_socket_all

15.5 remove CURLOPT_FAILONERROR

Remove support for CURLOPT_FAILONERROR, it has gotten too kludgy and weird internally. Let the app judge success or not for itself.

15.6 remove CURLOPT_DNS_USE_GLOBAL_CACHE

Remove support for a global DNS cache. Anything global is silly, and we already offer the share interface for the same functionality but done "right".

15.7 remove progress meter from libcurl

The internally provided progress meter output doesn't belong in the library. Basically no application wants it (apart from curl) but instead applications can and should do their own progress meters using the progress callback.

The progress callback should then be bumped as well to get proper 64bit variable types passed to it instead of doubles so that big files work correctly.

15.8 remove 'curl_httppost' from public

curl_formadd() was made to fill in a public struct, but the fact that the struct is public is never really used by application for their own advantage but instead often restricts how the form functions can or can't be modified.

Changing them to return a private handle will benefit the implementation and allow us much greater freedoms while still maintining a solid API and ABI.

15.9 have form functions use CURL handle argument

curl_formadd() and curl_formget() both currently have no CURL handle argument, but both can use a callback that is set in the easy handle, and thus curl_formget() with callback cannot function without first having curl_easy_perform() (or similar) called - which is hard to grasp and a design mistake.

Page updated January 5, 2012.
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