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cURL > Docs > TODO

TODO -- what to expect of the curl future

libcurl

1.1 Zero-copy interface
1.2 More data sharing
1.3 struct lifreq
1.4 signal-based resolver timeouts

libcurl - multi interface

2.1 More non-blocking
2.2 Remove easy interface internally
2.3 Avoid having to remove/readd handles
2.4 Fix HTTP Pipelining for PUT

Documentation

3.1 More and better

FTP

4.1 PRET
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 PORT port range
4.7 ASCII support

HTTP

5.1 Better persistency for HTTP 1.0
5.2 support FF3 sqlite cookie files

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
7.8 Support SRP on the TLS layer
7.9 improve configure --with-ssl

GnuTLS

8.1 Make NTLM work without OpenSSL functions
8.2 SSL engine stuff
8.3 SRP
8.4 non-blocking
8.5 check connection

Other protocols

9.1 ditch ldap-specific select

New protocols

10.1 RTSP
10.2 RSYNC
10.3 RTMP

Client

11.1 Content-Disposition
11.2 sync
11.3 glob posts
11.4 prevent file overwriting
11.5 ftp wildcard download
11.6 simultaneous parallel transfers
11.7 provide formpost headers
11.8 url-specific options
11.9 metalink support
11.10 warning when setting an option

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



1. libcurl

1.1 Zero-copy interface

Introduce another callback interface for upload/download that makes one less
copy of data and thus a faster operation.
[http://curl.haxx.se/dev/no_copy_callbacks.txt]

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.

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. The GnuTLS connection etc.

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().

2.3 Avoid having to remove/readd handles

curl_multi_handle_control() - this can control the easy handle (while) added
to a multi handle in various ways:

o RESTART, unconditionally restart this easy handle's transfer from the
start, re-init the state

o RESTART_COMPLETED, restart this easy handle's transfer but only if the
existing transfer has already completed and it is in a "finished state".

o STOP, just stop this transfer and consider it completed

o PAUSE?

o RESUME?

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 PRET

PRET is a command that primarily "drftpd" supports, which could be useful
when using libcurl against such a server. It is a non-standard and a rather
oddly designed command, but...
http://curl.haxx.se/bug/feature.cgi?id=1729967

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) %0d 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 PORT port range

Make CURLOPT_FTPPORT support an additional port number on the IP/if/name,
like "blabla:[port]" or possibly even "blabla:[portfirst]-[portsecond]".
http://curl.haxx.se/bug/feature.cgi?id=1505166

4.7 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

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/).

7.8 Support SRP on the TLS layer

Peter Sylvester's patch for SRP on the TLS layer. Awaits OpenSSL support for
this, no need to support this in libcurl before there's an OpenSSL release
that does it.

7.9 improve configure --with-ssl

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

8. GnuTLS

8.1 Make NTLM work without OpenSSL functions

Get NTLM working using the functions provided by NSS. Not strictly
SSL/TLS related, but hey... Another option is to get available DES and
MD4 source code from the cryptopp library. They are fine license-wise,
but are C++.

8.2 SSL engine stuff

Is this even possible?

8.3 SRP

Work out a common method with Peter Sylvester's OpenSSL-patch for SRP on the
TLS to provide name and password. GnuTLS already supports it...

8.4 non-blocking

Fix the connection phase to be non-blocking when multi interface is used

8.5 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.

9. Other protocols

9.1 ditch ldap-specific select

/ Look over the implementation. The looping will have to "go away" from the
lib/ldap.c source file and get moved to the main network code so that the
multi interface and friends will work for LDAP as well.

9.2 stop TFTP blocking

Stop TFTP from being blocking and doing its own read loop in tftp_do.

10. New protocols

10.1 RTSP

RFC2326 (protocol - very HTTP-like, also contains URL description)

10.2 RSYNC

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

10.3 RTMP

There exists a patch that claims to introduce this protocol:
http://osdir.com/ml/gnu.gnash.devel2/2006-11/msg00278.html, further details
in the feature-request: http://curl.haxx.se/bug/feature.cgi?id=1843469

11. Client

11.1 Content-Disposition

Add option that is similar to -O but that takes the output file name from the
Content-Disposition: header, and/or uses the local file name used in
redirections for the cases the server bounces the request further to a
different file (name): http://curl.haxx.se/bug/feature.cgi?id=1364676

11.2 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.

11.3 glob posts

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

11.4 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.

11.5 ftp wildcard download

"curl ftp://site.com//.txt"

11.6 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

11.7 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...)

11.8 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.

11.9 metalink support

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

11.10 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.

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".

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