_ _ ____ _ ___| | | | _ \| | / __| | | | |_) | | | (__| |_| | _ <| |___ \___|\___/|_| \_\_____| 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! Be aware that these are things that we could do, or have once been considered things we could do. If you want to work on any of these areas, please consider bringing it up for discussions first on the mailing list so that we all agree it is still a good idea for the project! 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 Modified buffer size approach 1.7 Detect when called from within callbacks 1.8 Allow SSL (HTTPS) to proxy 1.9 Cache negative name resolves 1.10 Support IDNA2008 1.11 minimize dependencies with dynamicly loaded modules 2. libcurl - multi interface 2.1 More non-blocking 2.2 Fix HTTP Pipelining for PUT 2.3 Better support for same name resolves 3. Documentation 3.1 Update date and version in man pages 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 ASCII support 4.6 GSSAPI via Windows SSPI 4.7 STAT for LIST without data connection 5. HTTP 5.1 Better persistency for HTTP 1.0 5.2 support FF3 sqlite cookie files 5.3 Rearrange request header order 5.4 SPDY 5.5 auth= in URLs 5.6 Refuse "downgrade" redirects 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. SMTP 7.1 Pipelining 7.2 Enhanced capability support 8. POP3 8.1 Pipelining 8.2 Enhanced capability support 9. IMAP 9.1 Enhanced capability support 10. LDAP 10.1 SASL based authentication mechanisms 11. SMB 11.1 File listing support 11.2 Honor file timestamps 11.3 Use NTLMv2 12. New protocols 12.1 RSYNC 13. SSL 13.1 Disable specific versions 13.2 Provide mutex locking API 13.3 Evaluate SSL patches 13.4 Cache OpenSSL contexts 13.5 Export session ids 13.6 Provide callback for cert verification 13.7 improve configure --with-ssl 13.8 Support DANE 14. GnuTLS 14.1 SSL engine stuff 14.2 check connection 15. WinSSL/SChannel 15.1 Add support for client certificate authentication 15.2 Add support for custom server certificate validation 15.3 Add support for the --ciphers option 16. SASL 16.1 Other authentication mechanisms 16.2 Add QOP support to GSSAPI authentication 17. Client 17.1 sync 17.2 glob posts 17.3 prevent file overwriting 17.4 simultaneous parallel transfers 17.5 provide formpost headers 17.6 warning when setting an option 17.7 warning when sending binary output to terminal 17.8 offer color-coded HTTP header output 17.9 Choose the name of file in braces for complex URLs 18. Build 18.1 roffit 19. Test suite 19.1 SSL tunnel 19.2 nicer lacking perl message 19.3 more protocols supported 19.4 more platforms supported 19.5 Add support for concurrent connections 20. Next SONAME bump 20.1 http-style HEAD output for FTP 20.2 combine error codes 20.3 extend CURLOPT_SOCKOPTFUNCTION prototype 21. Next major release 21.1 cleanup return codes 21.2 remove obsolete defines 21.3 size_t 21.4 remove several functions 21.5 remove CURLOPT_FAILONERROR 21.6 remove CURLOPT_DNS_USE_GLOBAL_CACHE 21.7 remove progress meter from libcurl 21.8 remove 'curl_httppost' from public 21.9 have form functions use CURL handle argument 21.10 Add CURLOPT_MAIL_CLIENT option ============================================================================== 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 Modified buffer size approach Current libcurl allocates a fixed 16K size buffer for download and an additional 16K for upload. They are always unconditionally part of the easy handle. If CRLF translations are requested, an additional 32K "scratch buffer" is allocated. A total of 64K transfer buffers in the worst case. First, while the handles are not actually in use these buffers could be freed so that lingering handles just kept in queues or whatever waste less memory. Secondly, SFTP is a protocol that needs to handle many ~30K blocks at once since each need to be individually acked and therefore libssh2 must be allowed to send (or receive) many separate ones in parallel to achieve high transfer speeds. A current libcurl build with a 16K buffer makes that impossible, but one with a 512K buffer will reach MUCH faster transfers. But allocating 512K unconditionally for all buffers just in case they would like to do fast SFTP transfers at some point is not a good solution either. Dynamically allocate buffer size depending on protocol in use in combination with freeing it after each individual transfer? Other suggestions? 1.7 Detect when called from within callbacks We should set a state variable before calling callbacks, so that we subsequently can add code within libcurl that returns error if called within callbacks for when that's not supported. 1.8 Allow SSL (HTTPS) to proxy To prevent local users from snooping on your traffic to the proxy. Supported by Chrome already: https://www.chromium.org/developers/design-documents/secure-web-proxy ...and by Firefox soon: https://bugzilla.mozilla.org/show_bug.cgi?id=378637 1.9 Cache negative name resolves A name resolve that has failed is likely to fail when made again within a short period of time. Currently we only cache positive responses. 1.10 Support IDNA2008 International Domain Names are supported in libcurl since years back, powered by libidn. libidn implements IDNA2003 which has been superseded by IDNA2008. libidn2 is an existing library offering support for IDNA2008. 1.11 minimize dependencies with dynamicly loaded modules We can create a system with loadable modules/plug-ins, where these modules would be the ones that link to 3rd party libs. That would allow us to avoid having to load ALL dependencies since only the necessary ones for this app/invoke/used protocols would be necessary to load. See https://github.com/bagder/curl/issues/349 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 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. 2.3 Better support for same name resolves If a name resolve has been initiated for name NN and a second easy handle wants to resolve that name as well, make it wait for the first resolve to end up in the cache instead of doing a second separate resolve. This is especially needed when adding many simultaneous handles using the same host name when the DNS resolver can get flooded. 3. Documentation 3.1 Update date and version in man pages 'maketgz' or another suitable script could update the .TH sections of the man pages at release time to use the current date and curl/libcurl version number. 4. FTP 4.1 HOST HOST is a command for a client to tell which host name to use, to offer FTP servers named-based virtual hosting: https://tools.ietf.org/html/rfc7151 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 ASCII support FTP ASCII transfers do not follow RFC959. They don't convert the data accordingly. 4.6 GSSAPI via Windows SSPI In addition to currently supporting the SASL GSSAPI mechanism (Kerberos V5) via third-party GSS-API libraries, such as Heimdal or MIT Kerberos, also add support for GSSAPI authentication via Windows SSPI. 4.7 STAT for LIST without data connection Some FTP servers allow STAT for listing directories instead of using LIST, and the response is then sent over the control connection instead of as the otherwise usedw data connection: http://www.nsftools.com/tips/RawFTP.htm#STAT This is not detailed in any FTP specification. 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. 5.4 SPDY Chrome and Firefox already support SPDY and lots of web services do. There's a library for us to use for this (spdylay) that has a similar API and the same author as nghttp2. spdylay: https://github.com/tatsuhiro-t/spdylay 5.5 auth= in URLs Add the ability to specify the preferred authentication mechanism to use by using ;auth= in the login part of the URL. For example: http://test:pass;auth=NTLM@example.com would be equivalent to specifying --user test:pass;auth=NTLM or --user test:pass --ntlm from the command line. Additionally this should be implemented for proxy base URLs as well. 5.6 Refuse "downgrade" redirects See https://github.com/bagder/curl/issues/226 Consider a way to tell curl to refuse to "downgrade" protocol with a redirect and/or possibly a bit that refuses redirect to change protocol completely. 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. SMTP 7.1 Pipelining Add support for pipelining emails. 7.2 Enhanced capability support Add the ability, for an application that uses libcurl, to obtain the list of capabilities returned from the EHLO command. 8. POP3 8.1 Pipelining Add support for pipelining commands. 8.2 Enhanced capability support Add the ability, for an application that uses libcurl, to obtain the list of capabilities returned from the CAPA command. 9. IMAP 9.1 Enhanced capability support Add the ability, for an application that uses libcurl, to obtain the list of capabilities returned from the CAPABILITY command. 10. LDAP 10.1 SASL based authentication mechanisms Currently the LDAP module only supports ldap_simple_bind_s() in order to bind to an LDAP server. However, this function sends username and password details using the simple authentication mechanism (as clear text). However, it should be possible to use ldap_bind_s() instead specifying the security context information ourselves. 11. SMB 11.1 File listing support Add support for listing the contents of a SMB share. The output should probably be the same as/similar to FTP. 11.2 Honor file timestamps The timestamp of the transferred file should reflect that of the original file. 11.3 Use NTLMv2 Currently the SMB authentication uses NTLMv1. 12. New protocols 12.1 RSYNC There's no RFC for the protocol or an URI/URL format. An implementation should most probably use an existing rsync library, such as librsync. 13. SSL 13.1 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 13.2 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. 13.3 Evaluate SSL patches Evaluate/apply Gertjan van Wingerde's SSL patches: http://curl.haxx.se/mail/lib-2004-03/0087.html 13.4 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. 13.5 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". 13.6 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! 13.7 improve configure --with-ssl make the configure --with-ssl option first check for OpenSSL, then GnuTLS, then NSS... 13.8 Support DANE DNS-Based Authentication of Named Entities (DANE) is a way to provide SSL keys and certs over DNS using DNSSEC as an alternative to the CA model. https://www.rfc-editor.org/rfc/rfc6698.txt An initial patch was posted by Suresh Krishnaswamy on March 7th 2013 (http://curl.haxx.se/mail/lib-2013-03/0075.html) but it was a too simple approach. See Daniel's comments: http://curl.haxx.se/mail/lib-2013-03/0103.html . libunbound may be the correct library to base this development on. 14. GnuTLS 14.1 SSL engine stuff Is this even possible? 14.2 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. 15. WinSSL/SChannel 15.1 Add support for client certificate authentication WinSSL/SChannel currently makes use of the OS-level system and user certificate and private key stores. This does not allow the application or the user to supply a custom client certificate using curl or libcurl. Therefore support for the existing -E/--cert and --key options should be implemented by supplying a custom certificate to the SChannel APIs, see: - Getting a Certificate for Schannel https://msdn.microsoft.com/en-us/library/windows/desktop/aa375447.aspx 15.2 Add support for custom server certificate validation WinSSL/SChannel currently makes use of the OS-level system and user certificate trust store. This does not allow the application or user to customize the server certificate validation process using curl or libcurl. Therefore support for the existing --cacert or --capath options should be implemented by supplying a custom certificate to the SChannel APIs, see: - Getting a Certificate for Schannel https://msdn.microsoft.com/en-us/library/windows/desktop/aa375447.aspx 15.3 Add support for the --ciphers option The cipher suites used by WinSSL/SChannel are configured on an OS-level instead of an application-level. This does not allow the application or the user to customize the configured cipher suites using curl or libcurl. Therefore support for the existing --ciphers option should be implemented by mapping the OpenSSL/GnuTLS cipher suites to the SChannel APIs, see - Specifying Schannel Ciphers and Cipher Strengths https://msdn.microsoft.com/en-us/library/windows/desktop/aa380161.aspx 16. SASL 16.1 Other authentication mechanisms Add support for other authentication mechanisms such as OLP, GSS-SPNEGO and others. 16.2 Add QOP support to GSSAPI authentication Currently the GSSAPI authentication only supports the default QOP of auth (Authentication), whilst Kerberos V5 supports both auth-int (Authentication with integrity protection) and auth-conf (Authentication with integrity and privacy protection). 17. Client 17.1 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. 17.2 glob posts Globbing support for -d and -F, as in 'curl -d "name=foo[0-9]" URL'. This is easily scripted though. 17.3 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. 17.4 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 17.5 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...) 17.6 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. 17.7 warning when sending binary output to terminal Provide a way that prompts the user for confirmation before binary data is sent to the terminal, much in the style 'less' does it. 17.8 offer color-coded HTTP header output By offering different color output on the header name and the header contents, they could be made more readable and thus help users working on HTTP services. 17.9 Choose the name of file in braces for complex URLs When using braces to download a list of URLs and you use complicated names in the list of alternatives, it could be handy to allow curl to use other names when saving. Consider a way to offer that. Possibly like {partURL1:name1,partURL2:name2,partURL3:name3} where the name following the colon is the output name. See https://github.com/bagder/curl/issues/221 18. Build 18.1 roffit Consider extending 'roffit' to produce decent ASCII output, and use that instead of (g)nroff when building src/tool_hugehelp.c 19. Test suite 19.1 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 19.2 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. 19.3 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). 19.4 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. 19.5 Add support for concurrent connections Tests 836, 882 and 938 were designed to verify that separate connections aren't used when using different login credentials in protocols that shouldn't re-use a connection under such circumstances. Unfortunately, ftpserver.pl doesn't appear to support multiple concurrent connections. The read while() loop seems to loop until it receives a disconnect from the client, where it then enters the waiting for connections loop. When the client opens a second connection to the server, the first connection hasn't been dropped (unless it has been forced - which we shouldn't do in these tests) and thus the wait for connections loop is never entered to receive the second connection. 20. Next SONAME bump 20.1 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 20.2 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 20.3 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. 21. Next major release 21.1 cleanup return codes curl_easy_cleanup() returns void, but curl_multi_cleanup() returns a CURLMcode. These should be changed to be the same. 21.2 remove obsolete defines remove obsolete defines from curl/curl.h 21.3 size_t make several functions use size_t instead of int in their APIs 21.4 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 21.5 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. 21.6 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". 21.7 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. 21.8 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 maintaining a solid API and ABI. 21.9 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. 21.10 Add CURLOPT_MAIL_CLIENT option Rather than use the URL to specify the mail client string to present in the HELO and EHLO commands, libcurl should support a new CURLOPT specifically for specifying this data as the URL is non-standard and to be honest a bit of a hack ;-) Please see the following thread for more information: http://curl.haxx.se/mail/lib-2012-05/0178.html