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Things that could be nice to do in the future
Things to do in project cURL. Please tell us what you think, contribute and
send us patches that improve things!
All bugs documented in the KNOWN_BUGS document are subject for fixing!
1. libcurl
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
2. libcurl - multi interface
2.1 More non-blocking
2.2 Remove easy interface internally
2.4 Fix HTTP Pipelining for PUT
3. Documentation
3.1 More and better
4. 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
5. HTTP
5.1 Better persistency for HTTP 1.0
5.2 support FF3 sqlite cookie files
5.3 Rearrange request header order
6. TELNET
6.1 ditch stdin
6.2 ditch telnet-specific select
6.3 feature negotiation debug data
6.4 send data in chunks
7. 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
8. GnuTLS
8.1 SSL engine stuff
8.3 check connection
8.4 non-gcrypt
9. Other protocols
10. New protocols
10.1 RSYNC
11. 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
12. Build
12.1 roffit
13. Test suite
13.1 SSL tunnel
13.2 nicer lacking perl message
13.3 more protocols supported
13.4 more platforms supported
14. Next SONAME bump
14.1 http-style HEAD output for ftp
14.2 combine error codes
14.3 extend CURLOPT_SOCKOPTFUNCTION prototype
15. 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) %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 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.