diff options
author | Kirill Volinsky <mataes2007@gmail.com> | 2013-11-10 18:02:01 +0000 |
---|---|---|
committer | Kirill Volinsky <mataes2007@gmail.com> | 2013-11-10 18:02:01 +0000 |
commit | ac48668a549fe76648e0ac3f93c9943383e043f5 (patch) | |
tree | bcfcf258bd003db20b1ee41fbbff173c8f340031 /plugins/FTPFileYM/curl-7.29.0/docs/FAQ | |
parent | 64e1340acd813704c9e9009b0a4e6fc9a3fb5adf (diff) |
curl folder renamed
git-svn-id: http://svn.miranda-ng.org/main/trunk@6858 1316c22d-e87f-b044-9b9b-93d7a3e3ba9c
Diffstat (limited to 'plugins/FTPFileYM/curl-7.29.0/docs/FAQ')
-rw-r--r-- | plugins/FTPFileYM/curl-7.29.0/docs/FAQ | 1465 |
1 files changed, 0 insertions, 1465 deletions
diff --git a/plugins/FTPFileYM/curl-7.29.0/docs/FAQ b/plugins/FTPFileYM/curl-7.29.0/docs/FAQ deleted file mode 100644 index 48075cea6d..0000000000 --- a/plugins/FTPFileYM/curl-7.29.0/docs/FAQ +++ /dev/null @@ -1,1465 +0,0 @@ - _ _ ____ _ - ___| | | | _ \| | - / __| | | | |_) | | - | (__| |_| | _ <| |___ - \___|\___/|_| \_\_____| - -FAQ - - 1. Philosophy - 1.1 What is cURL? - 1.2 What is libcurl? - 1.3 What is curl not? - 1.4 When will you make curl do XXXX ? - 1.5 Who makes curl? - 1.6 What do you get for making curl? - 1.7 What about CURL from curl.com? - 1.8 I have a problem who do I mail? - 1.9 Where do I buy commercial support for curl? - 1.10 How many are using curl? - 1.11 Why don't you update ca-bundle.crt - 1.12 I have a problem who can I chat with? - 1.13 curl's ECCN number? - 1.14 How do I submit my patch? - - 2. Install Related Problems - 2.1 configure doesn't find OpenSSL even when it is installed - 2.1.1 native linker doesn't find OpenSSL - 2.1.2 only the libssl lib is missing - 2.2 Does curl work/build with other SSL libraries? - 2.3 Where can I find a copy of LIBEAY32.DLL? - 2.4 Does curl support SOCKS (RFC 1928) ? - - 3. Usage Problems - 3.1 curl: (1) SSL is disabled, https: not supported - 3.2 How do I tell curl to resume a transfer? - 3.3 Why doesn't my posting using -F work? - 3.4 How do I tell curl to run custom FTP commands? - 3.5 How can I disable the Accept: */* header? - 3.6 Does curl support ASP, XML, XHTML or HTML version Y? - 3.7 Can I use curl to delete/rename a file through FTP? - 3.8 How do I tell curl to follow HTTP redirects? - 3.9 How do I use curl in my favorite programming language? - 3.10 What about SOAP, WebDAV, XML-RPC or similar protocols over HTTP? - 3.11 How do I POST with a different Content-Type? - 3.12 Why do FTP specific features over HTTP proxy fail? - 3.13 Why does my single/double quotes fail? - 3.14 Does curl support Javascript or PAC (automated proxy config)? - 3.15 Can I do recursive fetches with curl? - 3.16 What certificates do I need when I use SSL? - 3.17 How do I list the root dir of an FTP server? - 3.18 Can I use curl to send a POST/PUT and not wait for a response? - 3.19 How do I get HTTP from a host using a specific IP address? - 3.20 How to SFTP from my user's home directory? - 3.21 Protocol xxx not supported or disabled in libcurl - 3.22 curl -X gives me HTTP problems - - 4. Running Problems - 4.1 Problems connecting to SSL servers. - 4.2 Why do I get problems when I use & or % in the URL? - 4.3 How can I use {, }, [ or ] to specify multiple URLs? - 4.4 Why do I get downloaded data even though the web page doesn't exist? - 4.5 Why do I get return code XXX from a HTTP server? - 4.5.1 "400 Bad Request" - 4.5.2 "401 Unauthorized" - 4.5.3 "403 Forbidden" - 4.5.4 "404 Not Found" - 4.5.5 "405 Method Not Allowed" - 4.5.6 "301 Moved Permanently" - 4.6 Can you tell me what error code 142 means? - 4.7 How do I keep user names and passwords secret in Curl command lines? - 4.8 I found a bug! - 4.9 Curl can't authenticate to the server that requires NTLM? - 4.10 My HTTP request using HEAD, PUT or DELETE doesn't work! - 4.11 Why does my HTTP range requests return the full document? - 4.12 Why do I get "certificate verify failed" ? - 4.13 Why is curl -R on Windows one hour off? - 4.14 Redirects work in browser but not with curl! - 4.15 FTPS doesn't work - 4.16 My HTTP POST or PUT requests are slow! - 4.17 Non-functional connect timeouts on Windows - 4.18 file:// URLs containing drive letters (Windows, NetWare) - 4.19 Why doesn't cURL return an error when the network cable is unplugged? - - 5. libcurl Issues - 5.1 Is libcurl thread-safe? - 5.2 How can I receive all data into a large memory chunk? - 5.3 How do I fetch multiple files with libcurl? - 5.4 Does libcurl do Winsock initing on win32 systems? - 5.5 Does CURLOPT_WRITEDATA and CURLOPT_READDATA work on win32 ? - 5.6 What about Keep-Alive or persistent connections? - 5.7 Link errors when building libcurl on Windows! - 5.8 libcurl.so.X: open failed: No such file or directory - 5.9 How does libcurl resolve host names? - 5.10 How do I prevent libcurl from writing the response to stdout? - 5.11 How do I make libcurl not receive the whole HTTP response? - 5.12 Can I make libcurl fake or hide my real IP address? - 5.13 How do I stop an ongoing transfer? - 5.14 Using C++ non-static functions for callbacks? - 5.15 How do I get an FTP directory listing? - 5.16 I want a different time-out! - 5.17 Can I write a server with libcurl? - - 6. License Issues - 6.1 I have a GPL program, can I use the libcurl library? - 6.2 I have a closed-source program, can I use the libcurl library? - 6.3 I have a BSD licensed program, can I use the libcurl library? - 6.4 I have a program that uses LGPL libraries, can I use libcurl? - 6.5 Can I modify curl/libcurl for my program and keep the changes secret? - 6.6 Can you please change the curl/libcurl license to XXXX? - 6.7 What are my obligations when using libcurl in my commercial apps? - - 7. PHP/CURL Issues - 7.1 What is PHP/CURL? - 7.2 Who wrote PHP/CURL? - 7.3 Can I perform multiple requests using the same handle? - -============================================================================== - -1. Philosophy - - 1.1 What is cURL? - - cURL is the name of the project. The name is a play on 'Client for URLs', - originally with URL spelled in uppercase to make it obvious it deals with - URLs. The fact it can also be pronounced 'see URL' also helped, it works as - an abbreviation for "Client URL Request Library" or why not the recursive - version: "Curl URL Request Library". - - The cURL project produces two products: - - libcurl - - A free and easy-to-use client-side URL transfer library, supporting DICT, - FILE, FTP, FTPS, GOPHER, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, POP3, - POP3S, RTMP, RTSP, SCP, SFTP, SMTP, SMTPS, TELNET and TFTP. - - libcurl supports HTTPS certificates, HTTP POST, HTTP PUT, FTP uploading, - kerberos, HTTP form based upload, proxies, cookies, user+password - authentication, file transfer resume, http proxy tunneling and more! - - libcurl is highly portable, it builds and works identically on numerous - platforms, including Solaris, NetBSD, FreeBSD, OpenBSD, Darwin, HPUX, - IRIX, AIX, Tru64, Linux, UnixWare, HURD, Windows, Amiga, OS/2, BeOS, Mac - OS X, Ultrix, QNX, OpenVMS, RISC OS, Novell NetWare, DOS, Symbian, OSF, - Android, Minix, IBM TPF and more... - - libcurl is free, thread-safe, IPv6 compatible, feature rich, well - supported and fast. - - curl - - A command line tool for getting or sending files using URL syntax. - - Since curl uses libcurl, curl supports the same wide range of common - Internet protocols that libcurl does. - - We pronounce curl and cURL with an initial k sound: [kurl]. - - There are numerous sub-projects and related projects that also use the word - curl in the project names in various combinations, but you should take - notice that this FAQ is directed at the command-line tool named curl (and - libcurl the library), and may therefore not be valid for other curl-related - projects. (There is however a small section for the PHP/CURL in this FAQ.) - - 1.2 What is libcurl? - - libcurl is a reliable and portable library which provides you with an easy - interface to a range of common Internet protocols. - - You can use libcurl for free in your application, be it open source, - commercial or closed-source. - - libcurl is most probably the most portable, most powerful and most often - used C-based multi-platform file transfer library on this planet - be it - open source or commercial. - - 1.3 What is curl not? - - Curl is not a wget clone. That is a common misconception. Never, during - curl's development, have we intended curl to replace wget or compete on its - market. Curl is targeted at single-shot file transfers. - - Curl is not a web site mirroring program. If you want to use curl to mirror - something: fine, go ahead and write a script that wraps around curl to make - it reality (like curlmirror.pl does). - - Curl is not an FTP site mirroring program. Sure, get and send FTP with curl - but if you want systematic and sequential behavior you should write a - script (or write a new program that interfaces libcurl) and do it. - - Curl is not a PHP tool, even though it works perfectly well when used from - or with PHP (when using the PHP/CURL module). - - Curl is not a program for a single operating system. Curl exists, compiles, - builds and runs under a wide range of operating systems, including all - modern Unixes (and a bunch of older ones too), Windows, Amiga, BeOS, OS/2, - OS X, QNX etc. - - 1.4 When will you make curl do XXXX ? - - We love suggestions of what to change in order to make curl and libcurl - better. We do however believe in a few rules when it comes to the future of - curl: - - * Curl -- the command line tool -- is to remain a non-graphical command line - tool. If you want GUIs or fancy scripting capabilities, you should look - for another tool that uses libcurl. - - * We do not add things to curl that other small and available tools already - do very fine at the side. Curl's output is fine to pipe into another - program or redirect to another file for the next program to interpret. - - * We focus on protocol related issues and improvements. If you wanna do more - magic with the supported protocols than curl currently does, chances are - big we will agree. If you wanna add more protocols, we may very well - agree. - - * If you want someone else to make all the work while you wait for us to - implement it for you, that is not a very friendly attitude. We spend a - considerable time already on maintaining and developing curl. In order to - get more out of us, you should consider trading in some of your time and - efforts in return. - - * If you write the code, chances are bigger that it will get into curl - faster. - - 1.5 Who makes curl? - - curl and libcurl are not made by any single individual. Daniel Stenberg is - project leader and main developer, but other persons' submissions are - important and crucial. Anyone can contribute and post their changes and - improvements and have them inserted in the main sources (of course on the - condition that developers agree on that the fixes are good). - - The full list of all contributors is found in the docs/THANKS file. - - curl is developed by a community, with Daniel at the wheel. - - 1.6 What do you get for making curl? - - Project cURL is entirely free and open. No person gets paid for developing - (lib)curl on full or even part time. We do this voluntarily on our spare - time. Occasionally companies pay individual developers to work on curl, but - that's up to each company and developer. It is not controlled by nor - supervised in any way by the project. - - We still get help from companies. Haxx provides web site, bandwidth, mailing - lists etc and sourceforge.net hosts project services we take advantage from, - like the bug tracker. Also again, some companies have sponsored certain - parts of the development in the past and I hope some will continue to do so - in the future. - - If you want to support our project, consider a donation or a banner-program - or even better: by helping us coding, documenting, testing etc. - - 1.7 What about CURL from curl.com? - - During the summer 2001, curl.com was busy advertising their client-side - programming language for the web, named CURL. - - We are in no way associated with curl.com or their CURL programming - language. - - Our project name curl has been in effective use since 1998. We were not the - first computer related project to use the name "curl" and do not claim any - first-hand rights to the name. - - We recognize that we will be living in parallel with curl.com and wish them - every success. - - 1.8 I have a problem who do I mail? - - Please do not mail any single individual unless you really need to. Keep - curl-related questions on a suitable mailing list. All available mailing - lists are listed in the MANUAL document and online at - http://curl.haxx.se/mail/ - - Keeping curl-related questions and discussions on mailing lists allows - others to join in and help, to share their ideas, contribute their - suggestions and spread their wisdom. Keeping discussions on public mailing - lists also allows for others to learn from this (both current and future - users thanks to the web based archives of the mailing lists), thus saving us - from having to repeat ourselves even more. Thanks for respecting this. - - If you have found or simply suspect a security problem in curl or libcurl, - mail curl-security at haxx.se (closed list of receivers, mails are not - disclosed) and tell. Then we can produce a fix in a timely manner before the - flaw is announced to the world, thus lessen the impact the problem will have - on existing users. - - 1.9 Where do I buy commercial support for curl? - - curl is fully open source. It means you can hire any skilled engineer to fix - your curl-related problems. - - We list available alternatives on the curl web site: - http://curl.haxx.se/support.html - - 1.10 How many are using curl? - - It is impossible to tell. - - We don't know how many users that knowingly have installed and use curl. - - We don't know how many users that use curl without knowing that they are in - fact using it. - - We don't know how many users that downloaded or installed curl and then - never use it. - - In May 2012 Daniel did a counting game and came up with a number that may - be completely wrong or somewhat accurate. 300 million! - - See http://daniel.haxx.se/blog/2012/05/16/300m-users/ - - 1.11 Why don't you update ca-bundle.crt - - The ca-bundle.crt file that used to be bundled with curl was very outdated - (it being last modified year 2000 should tell) and must be replaced with a - much more modern and up-to-date version by anyone who wants to verify peers - anyway. It is no longer provided, the last curl release that shipped it was - curl 7.18.0. - - In the cURL project we've decided not to attempt to keep this file updated - (or even present anymore) since deciding what to add to a ca cert bundle is - an undertaking we've not been ready to accept, and the one we can get from - Mozilla is perfectly fine so there's no need to duplicate that work. - - Today, with many services performed over HTTPS, every operating system - should come with a default ca cert bundle that can be deemed somewhat - trustworthy and that collection (if reasonably updated) should be deemed to - be a lot better than a private curl version. - - If you want the most recent collection of ca certs that Mozilla Firefox - uses, we recommend that you extract the collection yourself from Mozilla - Firefox (by running 'make ca-bundle), or by using our online service setup - for this purpose: http://curl.haxx.se/docs/caextract.html - - 1.12 I have a problem who can I chat with? - - There's a bunch of friendly people hanging out in the #curl channel on the - IRC network irc.freenode.net. If you're polite and nice, chances are big - that you can get -- or provide -- help instantly. - - 1.13 curl's ECCN number? - - The US government restricts exports of software that contains or uses - cryptography. When doing so, the Export Control Classification Number (ECCN) - is used to identify the level of export control etc. - - ASF gives a good explanation at http://www.apache.org/dev/crypto.html - - We believe curl's number might be ECCN 5D002, another possibility is - 5D992. It seems necessary to write them, asking to confirm. - - Comprehensible explanations of the meaning of such numbers and how to - obtain them (resp.) are here - - http://www.bis.doc.gov/licensing/exportingbasics.htm - http://www.bis.doc.gov/licensing/do_i_needaneccn.html - - An incomprehensible description of the two numbers above is here - http://www.access.gpo.gov/bis/ear/pdf/ccl5-pt2.pdf - - 1.14 How do I submit my patch? - - When you have made a patch or a change of whatever sort, and want to submit - that to the project, there are a few different ways we prefer: - - o send a patch to the curl-library mailing list. We're many subscribers - there and there are lots of people who can review patches, comment on them - and "receive" them properly. - - o if your patch changes or fixes a bug, you can also opt to submit a bug - report in the bug tracker and attach your patch there. There are less - people involved there. - - Lots of more details are found in the CONTRIBUTE and INTERNALS docs. - - -2. Install Related Problems - - 2.1 configure doesn't find OpenSSL even when it is installed - - This may be because of several reasons. - - 2.1.1 native linker doesn't find openssl - - Affected platforms: - Solaris (native cc compiler) - HPUX (native cc compiler) - SGI IRIX (native cc compiler) - SCO UNIX (native cc compiler) - - When configuring curl, I specify --with-ssl. OpenSSL is installed in - /usr/local/ssl Configure reports SSL in /usr/local/ssl, but fails to find - CRYPTO_lock in -lcrypto - - Cause: The cc for this test places the -L/usr/local/ssl/lib AFTER - -lcrypto, so ld can't find the library. This is due to a bug in the GNU - autoconf tool. - - Workaround: Specifying "LDFLAGS=-L/usr/local/ssl/lib" in front of - ./configure places the -L/usr/local/ssl/lib early enough in the command - line to make things work - - 2.1.2 only the libssl lib is missing - - If all include files and the libcrypto lib is present, with only the - libssl being missing according to configure, this is mostly likely because - a few functions are left out from the libssl. - - If the function names missing include RSA or RSAREF you can be certain - that this is because libssl requires the RSA and RSAREF libs to build. - - See the INSTALL file section that explains how to add those libs to - configure. Make sure that you remove the config.cache file before you - rerun configure with the new flags. - - 2.2 Does curl work/build with other SSL libraries? - - Curl has been written to use a generic SSL function layer internally, and - that SSL functionality can then be provided by one out of many different SSL - backends. - - curl can be built to use one of the following SSL alternatives: OpenSSL, - GnuTLS, yassl, NSS, PolarSSL, axTLS, Secure Transport (native iOS/OS X), - schannel (native Windows) or qssl (native IBM i). They all have their pros - and cons, and we try to maintain a comparison of them here: - http://curl.haxx.se/docs/ssl-compared.html - - 2.3 Where can I find a copy of LIBEAY32.DLL? - - That is an OpenSSL binary built for Windows. - - Curl uses OpenSSL to do the SSL stuff. The LIBEAY32.DLL is what curl needs - on a windows machine to do https://. Check out the curl web site to find - accurate and up-to-date pointers to recent OpenSSL DLLs and other binary - packages. - - 2.4 Does curl support SOCKS (RFC 1928) ? - - Yes, SOCKS 4 and 5 are supported. - - -3. Usage problems - - 3.1 curl: (1) SSL is disabled, https: not supported - - If you get this output when trying to get anything from a https:// server, - it means that the instance of curl/libcurl that you're using was built - without support for this protocol. - - This could've happened if the configure script that was run at build time - couldn't find all libs and include files curl requires for SSL to work. If - the configure script fails to find them, curl is simply built without SSL - support. - - To get the https:// support into a curl that was previously built but that - reports that https:// is not supported, you should dig through the document - and logs and check out why the configure script doesn't find the SSL libs - and/or include files. - - Also, check out the other paragraph in this FAQ labelled "configure doesn't - find OpenSSL even when it is installed". - - 3.2 How do I tell curl to resume a transfer? - - Curl supports resumed transfers both ways on both FTP and HTTP. - Try the -C option. - - 3.3 Why doesn't my posting using -F work? - - You can't simply use -F or -d at your choice. The web server that will - receive your post assumes one of the formats. If the form you're trying to - "fake" sets the type to 'multipart/form-data', then and only then you must - use the -F type. In all the most common cases, you should use -d which then - causes a posting with the type 'application/x-www-form-urlencoded'. - - This is described in some detail in the MANUAL and TheArtOfHttpScripting - documents, and if you don't understand it the first time, read it again - before you post questions about this to the mailing list. Also, try reading - through the mailing list archives for old postings and questions regarding - this. - - 3.4 How do I tell curl to run custom FTP commands? - - You can tell curl to perform optional commands both before and/or after a - file transfer. Study the -Q/--quote option. - - Since curl is used for file transfers, you don't normally use curl to - perform FTP commands without transferring anything. Therefore you must - always specify a URL to transfer to/from even when doing custom FTP - commands, or use -I which implies the "no body" option sent to libcurl. - - 3.5 How can I disable the Accept: */* header? - - You can change all internally generated headers by adding a replacement with - the -H/--header option. By adding a header with empty contents you safely - disable that one. Use -H "Accept:" to disable that specific header. - - 3.6 Does curl support ASP, XML, XHTML or HTML version Y? - - To curl, all contents are alike. It doesn't matter how the page was - generated. It may be ASP, PHP, Perl, shell-script, SSI or plain - HTML-files. There's no difference to curl and it doesn't even know what kind - of language that generated the page. - - See also item 3.14 regarding javascript. - - 3.7 Can I use curl to delete/rename a file through FTP? - - Yes. You specify custom FTP commands with -Q/--quote. - - One example would be to delete a file after you have downloaded it: - - curl -O ftp://download.com/coolfile -Q '-DELE coolfile' - - or rename a file after upload: - - curl -T infile ftp://upload.com/dir/ -Q "-RNFR infile" -Q "-RNTO newname" - - 3.8 How do I tell curl to follow HTTP redirects? - - Curl does not follow so-called redirects by default. The Location: header - that informs the client about this is only interpreted if you're using the - -L/--location option. As in: - - curl -L http://redirector.com - - Not all redirects are HTTP ones, see 4.14 - - 3.9 How do I use curl in my favorite programming language? - - There exist many language interfaces/bindings for curl that integrates it - better with various languages. If you are fluid in a script language, you - may very well opt to use such an interface instead of using the command line - tool. - - Find out more about which languages that support curl directly, and how to - install and use them, in the libcurl section of the curl web site: - http://curl.haxx.se/libcurl/ - - All the various bindings to libcurl are made by other projects and people, - outside of the cURL project. The cURL project itself only produces libcurl - with its plain C API. If you don't find anywhere else to ask you can ask - about bindings on the curl-library list too, but be prepared that people on - that list may not know anything about bindings. - - In October 2009, there were interfaces available for the following - languages: Ada95, Basic, C, C++, Ch, Cocoa, D, Dylan, Eiffel, Euphoria, - Ferite, Gambas, glib/GTK+, Haskell, ILE/RPG, Java, Lisp, Lua, Mono, .NET, - Object-Pascal, O'Caml, Pascal, Perl, PHP, PostgreSQL, Python, R, Rexx, Ruby, - Scheme, S-Lang, Smalltalk, SP-Forth, SPL, Tcl, Visual Basic, Visual FoxPro, - Q, wxwidgets and XBLite. By the time you read this, additional ones may have - appeared! - - 3.10 What about SOAP, WebDAV, XML-RPC or similar protocols over HTTP? - - Curl adheres to the HTTP spec, which basically means you can play with *any* - protocol that is built on top of HTTP. Protocols such as SOAP, WEBDAV and - XML-RPC are all such ones. You can use -X to set custom requests and -H to - set custom headers (or replace internally generated ones). - - Using libcurl is of course just as fine and you'd just use the proper - library options to do the same. - - 3.11 How do I POST with a different Content-Type? - - You can always replace the internally generated headers with -H/--header. - To make a simple HTTP POST with text/xml as content-type, do something like: - - curl -d "datatopost" -H "Content-Type: text/xml" [URL] - - 3.12 Why do FTP specific features over HTTP proxy fail? - - Because when you use a HTTP proxy, the protocol spoken on the network will - be HTTP, even if you specify a FTP URL. This effectively means that you - normally can't use FTP specific features such as FTP upload and FTP quote - etc. - - There is one exception to this rule, and that is if you can "tunnel through" - the given HTTP proxy. Proxy tunneling is enabled with a special option (-p) - and is generally not available as proxy admins usually disable tunneling to - other ports than 443 (which is used for HTTPS access through proxies). - - 3.13 Why does my single/double quotes fail? - - To specify a command line option that includes spaces, you might need to - put the entire option within quotes. Like in: - - curl -d " with spaces " url.com - - or perhaps - - curl -d ' with spaces ' url.com - - Exactly what kind of quotes and how to do this is entirely up to the shell - or command line interpreter that you are using. For most unix shells, you - can more or less pick either single (') or double (") quotes. For - Windows/DOS prompts I believe you're forced to use double (") quotes. - - Please study the documentation for your particular environment. Examples in - the curl docs will use a mix of both these ones as shown above. You must - adjust them to work in your environment. - - Remember that curl works and runs on more operating systems than most single - individuals have ever tried. - - 3.14 Does curl support Javascript or PAC (automated proxy config)? - - Many web pages do magic stuff using embedded Javascript. Curl and libcurl - have no built-in support for that, so it will be treated just like any other - contents. - - .pac files are a netscape invention and are sometimes used by organizations - to allow them to differentiate which proxies to use. The .pac contents is - just a Javascript program that gets invoked by the browser and that returns - the name of the proxy to connect to. Since curl doesn't support Javascript, - it can't support .pac proxy configuration either. - - Some workarounds usually suggested to overcome this Javascript dependency: - - - Depending on the Javascript complexity, write up a script that - translates it to another language and execute that. - - - Read the Javascript code and rewrite the same logic in another language. - - - Implement a Javascript interpreter, people have successfully used the - Mozilla Javascript engine in the past. - - - Ask your admins to stop this, for a static proxy setup or similar. - - 3.15 Can I do recursive fetches with curl? - - No. curl itself has no code that performs recursive operations, such as - those performed by wget and similar tools. - - There exist wrapper scripts with that functionality (for example the - curlmirror perl script), and you can write programs based on libcurl to do - it, but the command line tool curl itself cannot. - - 3.16 What certificates do I need when I use SSL? - - There are three different kinds of "certificates" to keep track of when we - talk about using SSL-based protocols (HTTPS or FTPS) using curl or libcurl. - - - Client certificate. The server you communicate may require that you can - provide this in order to prove that you actually are who you claim to be. - If the server doesn't require this, you don't need a client certificate. - - A client certificate is always used together with a private key, and the - private key has a pass phrase that protects it. - - - Server certificate. The server you communicate with has a server - certificate. You can and should verify this certificate to make sure that - you are truly talking to the real server and not a server impersonating - it. - - - Certificate Authority certificate ("CA cert"). You often have several CA - certs in a CA cert bundle that can be used to verify a server certificate - that was signed by one of the authorities in the bundle. curl does not - come with a CA cert bundle but most curl installs provide one. You can - also override the default. - - The server certificate verification process is made by using a Certificate - Authority certificate ("CA cert") that was used to sign the server - certificate. Server certificate verification is enabled by default in curl - and libcurl and is often the reason for problems as explained in FAQ entry - 4.12 and the SSLCERTS document - (http://curl.haxx.se/docs/sslcerts.html). Server certificates that are - "self-signed" or otherwise signed by a CA that you do not have a CA cert - for, cannot be verified. If the verification during a connect fails, you - are refused access. You then need to explicitly disable the verification - to connect to the server. - - 3.17 How do I list the root dir of an FTP server? - - There are two ways. The way defined in the RFC is to use an encoded slash - in the first path part. List the "/tmp" dir like this: - - curl ftp://ftp.sunet.se/%2ftmp/ - - or the not-quite-kosher-but-more-readable way, by simply starting the path - section of the URL with a slash: - - curl ftp://ftp.sunet.se//tmp/ - - 3.18 Can I use curl to send a POST/PUT and not wait for a response? - - No. - - But you could easily write your own program using libcurl to do such stunts. - - 3.19 How do I get HTTP from a host using a specific IP address? - - For example, you may be trying out a web site installation that isn't yet in - the DNS. Or you have a site using multiple IP addresses for a given host - name and you want to address a specific one out of the set. - - Set a custom Host: header that identifies the server name you want to reach - but use the target IP address in the URL: - - curl --header "Host: www.example.com" http://127.0.0.1/ - - You can also opt to add faked host name entries to curl with the --resolve - option. That has the added benefit that things like redirects will also work - properly. The above operation would instead be done as: - - curl --resolve www.example.com:80:127.0.0.1 http://www.example.com/ - - 3.20 How to SFTP from my user's home directory? - - Contrary to how FTP works, SFTP and SCP URLs specify the exact directory to - work with. It means that if you don't specify that you want the user's home - directory, you get the actual root directory. - - To specify a file in your user's home directory, you need to use the correct - URL syntax which for sftp might look similar to: - - curl -O -u user:password sftp://example.com/~/file.txt - - and for SCP it is just a different protocol prefix: - - curl -O -u user:password scp://example.com/~/file.txt - - 3.21 Protocol xxx not supported or disabled in libcurl - - When passing on a URL to curl to use, it may respond that the particular - protocol is not supported or disabled. The particular way this error message - is phrased is because curl doesn't make a distinction internally of whether - a particular protocol is not supported (ie never got any code added that - knows how to speak that protocol) or if it was explicitly disabled. curl can - be built to only support a given set of protocols, and the rest would then - be disabled or not supported. - - Note that this error will also occur if you pass a wrongly spelled protocol - part as in "htpt://example.com" or as in the less evident case if you prefix - the protocol part with a space as in " http://example.com/". - - 3.22 curl -X gives me HTTP problems - - In normal circumstances, -X should hardly ever be used. - - By default you use curl without explicitly saying which request method to - use when the URL identifies a HTTP transfer. If you just pass in a URL like - "curl http://example.com" it will use GET. If you use -d or -F curl will use - POST, -I will cause a HEAD and -T will make it a PUT. - - If for whatever reason you're not happy with these default choices that curl - does for you, you can override those request methods by specifying -X - [WHATEVER]. This way you can for example send a DELETE by doing "curl -X - DELETE [URL]". - - It is thus pointless to do "curl -XGET [URL]" as GET would be used - anyway. In the same vein it is pointless to do "curl -X POST -d data - [URL]"... But you can make a fun and somewhat rare request that sends a - request-body in a GET request with something like "curl -X GET -d data - [URL]" - - Note that -X doesn't change curl's behavior. It only modifies the actual - string sent in the request. - - Accordingly, by using -XPOST on a command line that for example would follow - a 303 redirect, you will effectively prevent curl from behaving - correctly. Be aware. - - -4. Running Problems - - 4.1 Problems connecting to SSL servers. - - It took a very long time before we could sort out why curl had problems to - connect to certain SSL servers when using SSLeay or OpenSSL v0.9+. The - error sometimes showed up similar to: - - 16570:error:1407D071:SSL routines:SSL2_READ:bad mac decode:s2_pkt.c:233: - - It turned out to be because many older SSL servers don't deal with SSLv3 - requests properly. To correct this problem, tell curl to select SSLv2 from - the command line (-2/--sslv2). - - There have also been examples where the remote server didn't like the SSLv2 - request and instead you had to force curl to use SSLv3 with -3/--sslv3. - - 4.2 Why do I get problems when I use & or % in the URL? - - In general unix shells, the & symbol is treated specially and when used, it - runs the specified command in the background. To safely send the & as a part - of a URL, you should quote the entire URL by using single (') or double (") - quotes around it. Similar problems can also occur on some shells with other - characters, including ?*!$~(){}<>\|;`. When in doubt, quote the URL. - - An example that would invoke a remote CGI that uses &-symbols could be: - - curl 'http://www.altavista.com/cgi-bin/query?text=yes&q=curl' - - In Windows, the standard DOS shell treats the %-symbol specially and you - need to use TWO %-symbols for each single one you want to use in the URL. - - Also note that if you want the literal %-symbol to be part of the data you - pass in a POST using -d/--data you must encode it as '%25' (which then also - needs the %-symbol doubled on Windows machines). - - 4.3 How can I use {, }, [ or ] to specify multiple URLs? - - Because those letters have a special meaning to the shell, and to be used in - a URL specified to curl you must quote them. - - An example that downloads two URLs (sequentially) would do: - - curl '{curl,www}.haxx.se' - - To be able to use those letters as actual parts of the URL (without using - them for the curl URL "globbing" system), use the -g/--globoff option: - - curl -g 'www.site.com/weirdname[].html' - - 4.4 Why do I get downloaded data even though the web page doesn't exist? - - Curl asks remote servers for the page you specify. If the page doesn't exist - at the server, the HTTP protocol defines how the server should respond and - that means that headers and a "page" will be returned. That's simply how - HTTP works. - - By using the --fail option you can tell curl explicitly to not get any data - if the HTTP return code doesn't say success. - - 4.5 Why do I get return code XXX from a HTTP server? - - RFC2616 clearly explains the return codes. This is a short transcript. Go - read the RFC for exact details: - - 4.5.1 "400 Bad Request" - - The request could not be understood by the server due to malformed - syntax. The client SHOULD NOT repeat the request without modifications. - - 4.5.2 "401 Unauthorized" - - The request requires user authentication. - - 4.5.3 "403 Forbidden" - - The server understood the request, but is refusing to fulfil it. - Authorization will not help and the request SHOULD NOT be repeated. - - 4.5.4 "404 Not Found" - - The server has not found anything matching the Request-URI. No indication - is given of whether the condition is temporary or permanent. - - 4.5.5 "405 Method Not Allowed" - - The method specified in the Request-Line is not allowed for the resource - identified by the Request-URI. The response MUST include an Allow header - containing a list of valid methods for the requested resource. - - 4.5.6 "301 Moved Permanently" - - If you get this return code and an HTML output similar to this: - - <H1>Moved Permanently</H1> The document has moved <A - HREF="http://same_url_now_with_a_trailing_slash/">here</A>. - - it might be because you request a directory URL but without the trailing - slash. Try the same operation again _with_ the trailing URL, or use the - -L/--location option to follow the redirection. - - 4.6 Can you tell me what error code 142 means? - - All curl error codes are described at the end of the man page, in the - section called "EXIT CODES". - - Error codes that are larger than the highest documented error code means - that curl has exited due to a crash. This is a serious error, and we - appreciate a detailed bug report from you that describes how we could go - ahead and repeat this! - - 4.7 How do I keep user names and passwords secret in Curl command lines? - - This problem has two sides: - - The first part is to avoid having clear-text passwords in the command line - so that they don't appear in 'ps' outputs and similar. That is easily - avoided by using the "-K" option to tell curl to read parameters from a file - or stdin to which you can pass the secret info. curl itself will also - attempt to "hide" the given password by blanking out the option - this - doesn't work on all platforms. - - To keep the passwords in your account secret from the rest of the world is - not a task that curl addresses. You could of course encrypt them somehow to - at least hide them from being read by human eyes, but that is not what - anyone would call security. - - Also note that regular HTTP (using Basic authentication) and FTP passwords - are sent in clear across the network. All it takes for anyone to fetch them - is to listen on the network. Eavesdropping is very easy. Use more secure - authentication methods (like Digest, Negotiate or even NTLM) or consider the - SSL-based alternatives HTTPS and FTPS. - - 4.8 I found a bug! - - It is not a bug if the behavior is documented. Read the docs first. - Especially check out the KNOWN_BUGS file, it may be a documented bug! - - If it is a problem with a binary you've downloaded or a package for your - particular platform, try contacting the person who built the package/archive - you have. - - If there is a bug, read the BUGS document first. Then report it as described - in there. - - 4.9 Curl can't authenticate to the server that requires NTLM? - - NTLM support requires OpenSSL, GnuTLS, NSS, Secure Transport, or Microsoft - Windows libraries at build-time to provide this functionality. - - NTLM is a Microsoft proprietary protocol. Proprietary formats are evil. You - should not use such ones. - - 4.10 My HTTP request using HEAD, PUT or DELETE doesn't work! - - Many web servers allow or demand that the administrator configures the - server properly for these requests to work on the web server. - - Some servers seem to support HEAD only on certain kinds of URLs. - - To fully grasp this, try the documentation for the particular server - software you're trying to interact with. This is not anything curl can do - anything about. - - 4.11 Why does my HTTP range requests return the full document? - - Because the range may not be supported by the server, or the server may - choose to ignore it and return the full document anyway. - - 4.12 Why do I get "certificate verify failed" ? - - You invoke curl 7.10 or later to communicate on a https:// URL and get an - error back looking something similar to this: - - curl: (35) SSL: error:14090086:SSL routines: - SSL3_GET_SERVER_CERTIFICATE:certificate verify failed - - Then it means that curl couldn't verify that the server's certificate was - good. Curl verifies the certificate using the CA cert bundle that comes with - the curl installation. - - To disable the verification (which makes it act like curl did before 7.10), - use -k. This does however enable man-in-the-middle attacks. - - If you get this failure but are having a CA cert bundle installed and used, - the server's certificate is not signed by one of the CA's in the bundle. It - might for example be self-signed. You then correct this problem by obtaining - a valid CA cert for the server. Or again, decrease the security by disabling - this check. - - Details are also in the SSLCERTS file in the release archives, found online - here: http://curl.haxx.se/docs/sslcerts.html - - 4.13 Why is curl -R on Windows one hour off? - - During daylight savings time, when -R is used, curl will set a time that - appears one hour off. This happens due to a flaw in how Windows stores and - uses file modification times and it is not easily worked around. For details - on this problem, read this: http://www.codeproject.com/datetime/dstbugs.asp - - 4.14 Redirects work in browser but not with curl! - - curl supports HTTP redirects fine (see item 3.8). Browsers generally support - at least two other ways to perform directs that curl does not: - - - Meta tags. You can write a HTML tag that will cause the browser to - redirect to another given URL after a certain time. - - - Javascript. You can write a Javascript program embedded in a HTML page - that redirects the browser to another given URL. - - There is no way to make curl follow these redirects. You must either - manually figure out what the page is set to do, or you write a script that - parses the results and fetches the new URL. - - 4.15 FTPS doesn't work - - curl supports FTPS (sometimes known as FTP-SSL) both implicit and explicit - mode. - - When a URL is used that starts with FTPS://, curl assumes implicit SSL on - the control connection and will therefore immediately connect and try to - speak SSL. FTPS:// connections default to port 990. - - To use explicit FTPS, you use a FTP:// URL and the --ftp-ssl option (or one - of its related flavours). This is the most common method, and the one - mandated by RFC4217. This kind of connection then of course uses the - standard FTP port 21 by default. - - 4.16 My HTTP POST or PUT requests are slow! - - libcurl makes all POST and PUT requests (except for POST requests with a - very tiny request body) use the "Expect: 100-continue" header. This header - allows the server to deny the operation early so that libcurl can bail out - already before having to send any data. This is useful in authentication - cases and others. - - However, many servers don't implement the Expect: stuff properly and if the - server doesn't respond (positively) within 1 second libcurl will continue - and send off the data anyway. - - You can disable libcurl's use of the Expect: header the same way you disable - any header, using -H / CURLOPT_HTTPHEADER, or by forcing it to use HTTP 1.0. - - 4.17 Non-functional connect timeouts - - In most Windows setups having a timeout longer than 21 seconds make no - difference, as it will only send 3 TCP SYN packets and no more. The second - packet sent three seconds after the first and the third six seconds after - the second. No more than three packets are sent, no matter how long the - timeout is set. - - See option TcpMaxConnectRetransmissions on this page: - http://support.microsoft.com/?scid=kb%3Ben-us%3B175523&x=6&y=7 - - Also, even on non-Windows systems there may run a firewall or anti-virus - software or similar that accepts the connection but does not actually do - anything else. This will make (lib)curl to consider the connection connected - and thus the connect timeout won't trigger. - - 4.18 file:// URLs containing drive letters (Windows, NetWare) - - When using cURL to try to download a local file, one might use a URL - in this format: - - file://D:/blah.txt - - You'll find that even if D:\blah.txt does exist, cURL returns a 'file - not found' error. - - According to RFC 1738 (http://www.faqs.org/rfcs/rfc1738.html), - file:// URLs must contain a host component, but it is ignored by - most implementations. In the above example, 'D:' is treated as the - host component, and is taken away. Thus, cURL tries to open '/blah.txt'. - If your system is installed to drive C:, that will resolve to 'C:\blah.txt', - and if that doesn't exist you will get the not found error. - - To fix this problem, use file:// URLs with *three* leading slashes: - - file:///D:/blah.txt - - Alternatively, if it makes more sense, specify 'localhost' as the host - component: - - file://localhost/D:/blah.txt - - In either case, cURL should now be looking for the correct file. - - 4.19 Why doesn't cURL return an error when the network cable is unplugged? - - Unplugging the cable is not an error situation. The TCP/IP protocol stack - was designed to be fault tolerant, so even though there may be a physical - break somewhere the connection shouldn't be affected, just possibly - delayed. Eventually, the physical break will be fixed or the data will be - re-routed around the physical problem. - - In such cases, the TCP/IP stack is responsible for detecting when the - network connection is irrevocably lost. Since with some protocols it is - perfectly legal for the client wait indefinitely for data, the stack may - never report a problem, and even when it does, it can take up to 20 minutes - for it to detect an issue. The curl option --keepalive-time enables - keep-alive support in the TCP/IP stack which makes it periodically probe the - connection to make sure it is still available to send data. That should - reliably detect any TCP/IP network failure. - - But even that won't detect the network going down before the TCP/IP - connection is established (e.g. during a DNS lookup) or using protocols that - don't use TCP. To handle those situations, curl offers a number of timeouts - on its own. --speed-limit/--speed-time will abort if the data transfer rate - falls too low, and --connect-timeout and --max-time can be used to put an - overall timeout on the connection phase or the entire transfer. - - -5. libcurl Issues - - 5.1 Is libcurl thread-safe? - - Yes. - - We have written the libcurl code specifically adjusted for multi-threaded - programs. libcurl will use thread-safe functions instead of non-safe ones if - your system has such. - - If you use a OpenSSL-powered libcurl in a multi-threaded environment, you - need to provide one or two locking functions: - - http://www.openssl.org/docs/crypto/threads.html - - If you use a GnuTLS-powered libcurl in a multi-threaded environment, you - need to provide locking function(s) for libgcrypt (which is used by GnuTLS - for the crypto functions). - - http://www.gnu.org/software/gnutls/manual/html_node/Multi_002dthreaded-applications.html - - No special locking is needed with a NSS-powered libcurl. NSS is thread-safe. - - 5.2 How can I receive all data into a large memory chunk? - - [ See also the examples/getinmemory.c source ] - - You are in full control of the callback function that gets called every time - there is data received from the remote server. You can make that callback do - whatever you want. You do not have to write the received data to a file. - - One solution to this problem could be to have a pointer to a struct that you - pass to the callback function. You set the pointer using the - CURLOPT_WRITEDATA option. Then that pointer will be passed to the callback - instead of a FILE * to a file: - - /* imaginary struct */ - struct MemoryStruct { - char *memory; - size_t size; - }; - - /* imaginary callback function */ - size_t - WriteMemoryCallback(void *ptr, size_t size, size_t nmemb, void *data) - { - size_t realsize = size * nmemb; - struct MemoryStruct *mem = (struct MemoryStruct *)data; - - mem->memory = (char *)realloc(mem->memory, mem->size + realsize + 1); - if (mem->memory) { - memcpy(&(mem->memory[mem->size]), ptr, realsize); - mem->size += realsize; - mem->memory[mem->size] = 0; - } - return realsize; - } - - 5.3 How do I fetch multiple files with libcurl? - - libcurl has excellent support for transferring multiple files. You should - just repeatedly set new URLs with curl_easy_setopt() and then transfer it - with curl_easy_perform(). The handle you get from curl_easy_init() is not - only reusable, but you're even encouraged to reuse it if you can, as that - will enable libcurl to use persistent connections. - - 5.4 Does libcurl do Winsock initialization on win32 systems? - - Yes, if told to in the curl_global_init() call. - - 5.5 Does CURLOPT_WRITEDATA and CURLOPT_READDATA work on win32 ? - - Yes, but you cannot open a FILE * and pass the pointer to a DLL and have - that DLL use the FILE * (as the DLL and the client application cannot access - each others' variable memory areas). If you set CURLOPT_WRITEDATA you must - also use CURLOPT_WRITEFUNCTION as well to set a function that writes the - file, even if that simply writes the data to the specified FILE *. - Similarly, if you use CURLOPT_READDATA you must also specify - CURLOPT_READFUNCTION. - - 5.6 What about Keep-Alive or persistent connections? - - curl and libcurl have excellent support for persistent connections when - transferring several files from the same server. Curl will attempt to reuse - connections for all URLs specified on the same command line/config file, and - libcurl will reuse connections for all transfers that are made using the - same libcurl handle. - - When you use the easy interface, the connection cache is kept within the - easy handle. If you instead use the multi interface, the connection cache - will be kept within the multi handle and will be shared among all the easy - handles that are used within the same multi handle. - - 5.7 Link errors when building libcurl on Windows! - - You need to make sure that your project, and all the libraries (both static - and dynamic) that it links against, are compiled/linked against the same run - time library. - - This is determined by the /MD, /ML, /MT (and their corresponding /M?d) - options to the command line compiler. /MD (linking against MSVCRT dll) seems - to be the most commonly used option. - - When building an application that uses the static libcurl library, you must - add -DCURL_STATICLIB to your CFLAGS. Otherwise the linker will look for - dynamic import symbols. If you're using Visual Studio, you need to instead - add CURL_STATICLIB in the "Preprocessor Definitions" section. - - If you get linker error like "unknown symbol __imp__curl_easy_init ..." you - have linked against the wrong (static) library. If you want to use the - libcurl.dll and import lib, you don't need any extra CFLAGS, but use one of - the import libraries below. These are the libraries produced by the various - lib/Makefile.* files: - - Target: static lib. import lib for libcurl*.dll. - ----------------------------------------------------------- - MingW: libcurl.a libcurldll.a - MSVC (release): libcurl.lib libcurl_imp.lib - MSVC (debug): libcurld.lib libcurld_imp.lib - Borland: libcurl.lib libcurl_imp.lib - - 5.8 libcurl.so.X: open failed: No such file or directory - - This is an error message you might get when you try to run a program linked - with a shared version of libcurl and your run-time linker (ld.so) couldn't - find the shared library named libcurl.so.X. (Where X is the number of the - current libcurl ABI, typically 3 or 4). - - You need to make sure that ld.so finds libcurl.so.X. You can do that - multiple ways, and it differs somewhat between different operating systems, - but they are usually: - - * Add an option to the linker command line that specify the hard-coded path - the run-time linker should check for the lib (usually -R) - - * Set an environment variable (LD_LIBRARY_PATH for example) where ld.so - should check for libs - - * Adjust the system's config to check for libs in the directory where you've - put the dir (like Linux's /etc/ld.so.conf) - - 'man ld.so' and 'man ld' will tell you more details - - 5.9 How does libcurl resolve host names? - - libcurl supports a large a number of different name resolve functions. One - of them is picked at build-time and will be used unconditionally. Thus, if - you want to change name resolver function you must rebuild libcurl and tell - it to use a different function. - - - The non-ipv6 resolver that can use one out of four host name resolve calls - (depending on what your system supports): - - A - gethostbyname() - B - gethostbyname_r() with 3 arguments - C - gethostbyname_r() with 5 arguments - D - gethostbyname_r() with 6 arguments - - - The ipv6-resolver that uses getaddrinfo() - - - The c-ares based name resolver that uses the c-ares library for resolves. - Using this offers asynchronous name resolves. - - - The threaded resolver (default option on Windows). It uses: - - A - gethostbyname() on plain ipv4 hosts - B - getaddrinfo() on ipv6-enabled hosts - - Also note that libcurl never resolves or reverse-lookups addresses given as - pure numbers, such as 127.0.0.1 or ::1. - - 5.10 How do I prevent libcurl from writing the response to stdout? - - libcurl provides a default built-in write function that writes received data - to stdout. Set the CURLOPT_WRITEFUNCTION to receive the data, or possibly - set CURLOPT_WRITEDATA to a different FILE * handle. - - 5.11 How do I make libcurl not receive the whole HTTP response? - - You make the write callback (or progress callback) return an error and - libcurl will then abort the transfer. - - 5.12 Can I make libcurl fake or hide my real IP address? - - No. libcurl operates on a higher level than so. Besides, faking IP address - would imply sending IP packages with a made-up source address, and then you - normally get a problem with intercepting the packages sent back as they - would then not be routed to you! - - If you use a proxy to access remote sites, the sites will not see your local - IP address but instead the address of the proxy. - - Also note that on many networks NATs or other IP-munging techniques are used - that makes you see and use a different IP address locally than what the - remote server will see you coming from. - - 5.13 How do I stop an ongoing transfer? - - With the easy interface you make sure to return the correct error code from - one of the callbacks, but none of them are instant. There is no function you - can call from another thread or similar that will stop it immediately. - Instead, you need to make sure that one of the callbacks you use returns an - appropriate value that will stop the transfer. Suitable callbacks that you - can do this with include the progress callback, the read callback and the - write callback. - - If you're using the multi interface, you can also stop a transfer by - removing the particular easy handle from the multi stack at any moment you - think the transfer is done or when you wish to abort the transfer. - - 5.14 Using C++ non-static functions for callbacks? - - libcurl is a C library, it doesn't know anything about C++ member functions. - - You can overcome this "limitation" with a relative ease using a static - member function that is passed a pointer to the class: - - // f is the pointer to your object. - static YourClass::func(void *buffer, size_t sz, size_t n, void *f) - { - // Call non-static member function. - static_cast<YourClass*>(f)->nonStaticFunction(); - } - - // This is how you pass pointer to the static function: - curl_easy_setopt(hcurl, CURLOPT_WRITEFUNCTION, YourClass:func); - curl_easy_setopt(hcurl, CURLOPT_WRITEDATA, this); - - 5.15 How do I get an FTP directory listing? - - If you end the FTP URL you request with a slash, libcurl will provide you - with a directory listing of that given directory. You can also set - CURLOPT_CUSTOMREQUEST to alter what exact listing command libcurl would use - to list the files. - - The follow-up question that tend to follow the previous one, is how a - program is supposed to parse the directory listing. How does it know what's - a file and what's a dir and what's a symlink etc. The harsh reality is that - FTP provides no such fine and easy-to-parse output. The output format FTP - servers respond to LIST commands are entirely at the server's own liking and - the NLST output doesn't reveal any types and in many cases don't even - include all the directory entries. Also, both LIST and NLST tend to hide - unix-style hidden files (those that start with a dot) by default so you need - to do "LIST -a" or similar to see them. - - The application thus needs to parse the LIST output. One such existing - list parser is available at http://cr.yp.to/ftpparse.html Versions of - libcurl since 7.21.0 also provide the ability to specify a wildcard to - download multiple files from one FTP directory. - - 5.16 I want a different time-out! - - Time and time again users realize that CURLOPT_TIMEOUT and - CURLOPT_CONNECTIMEOUT are not sufficiently advanced or flexible to cover all - the various use cases and scenarios applications end up with. - - libcurl offers many more ways to time-out operations. A common alternative - is to use the CURLOPT_LOW_SPEED_LIMIT and CURLOPT_LOW_SPEED_TIME options to - specify the lowest possible speed to accept before to consider the transfer - timed out. - - The most flexible way is by writing your own time-out logic and using - CURLOPT_PROGRESSFUNCTION (perhaps in combination with other callbacks) and - use that to figure out exactly when the right condition is met when the - transfer should get stopped. - - 5.17 Can I write a server with libcurl? - - No. libcurl offers no functions or building blocks to build any kind of - internet protocol server. libcurl is only a client-side library. For server - libraries, you need to continue your search elsewhere but there exist many - good open source ones out there for most protocols you could possibly want a - server for. And there are really good stand-alone ones that have been tested - and proven for many years. There's no need for you to reinvent them! - - -6. License Issues - - Curl and libcurl are released under a MIT/X derivate license. The license is - very liberal and should not impose a problem for your project. This section - is just a brief summary for the cases we get the most questions. (Parts of - this section was much enhanced by Bjorn Reese.) - - We are not lawyers and this is not legal advice. You should probably consult - one if you want true and accurate legal insights without our prejudice. Note - especially that this section concerns the libcurl license only; compiling in - features of libcurl that depend on other libraries (e.g. OpenSSL) may affect - the licensing obligations of your application. - - 6.1 I have a GPL program, can I use the libcurl library? - - Yes! - - Since libcurl may be distributed under the MIT/X derivate license, it can be - used together with GPL in any software. - - 6.2 I have a closed-source program, can I use the libcurl library? - - Yes! - - libcurl does not put any restrictions on the program that uses the library. - - 6.3 I have a BSD licensed program, can I use the libcurl library? - - Yes! - - libcurl does not put any restrictions on the program that uses the library. - - 6.4 I have a program that uses LGPL libraries, can I use libcurl? - - Yes! - - The LGPL license doesn't clash with other licenses. - - 6.5 Can I modify curl/libcurl for my program and keep the changes secret? - - Yes! - - The MIT/X derivate license practically allows you to do almost anything with - the sources, on the condition that the copyright texts in the sources are - left intact. - - 6.6 Can you please change the curl/libcurl license to XXXX? - - No. - - We have carefully picked this license after years of development and - discussions and a large amount of people have contributed with source code - knowing that this is the license we use. This license puts the restrictions - we want on curl/libcurl and it does not spread to other programs or - libraries that use it. It should be possible for everyone to use libcurl or - curl in their projects, no matter what license they already have in use. - - 6.7 What are my obligations when using libcurl in my commercial apps? - - Next to none. All you need to adhere to is the MIT-style license (stated in - the COPYING file) which basically says you have to include the copyright - notice in "all copies" and that you may not use the copyright holder's name - when promoting your software. - - You do not have to release any of your source code. - - You do not have to reveal or make public any changes to the libcurl source - code. - - You do not have to broadcast to the world that you are using libcurl within - your app. - - All we ask is that you disclose "the copyright notice and this permission - notice" somewhere. Most probably like in the documentation or in the section - where other third party dependencies already are mentioned and acknowledged. - - As can be seen here: http://curl.haxx.se/docs/companies.html and elsewhere, - more and more companies are discovering the power of libcurl and take - advantage of it even in commercial environments. - - -7. PHP/CURL Issues - - 7.1 What is PHP/CURL? - - The module for PHP that makes it possible for PHP programs to access curl- - functions from within PHP. - - In the cURL project we call this module PHP/CURL to differentiate it from - curl the command line tool and libcurl the library. The PHP team however - does not refer to it like this (for unknown reasons). They call it plain - CURL (often using all caps) or sometimes ext/curl, but both cause much - confusion to users which in turn gives us a higher question load. - - 7.2 Who wrote PHP/CURL? - - PHP/CURL is a module that comes with the regular PHP package. It depends and - uses libcurl, so you need to have libcurl installed properly first before - PHP/CURL can be used. PHP/CURL was initially written by Sterling Hughes. - - 7.3 Can I perform multiple requests using the same handle? - - Yes - at least in PHP version 4.3.8 and later (this has been known to not - work in earlier versions, but the exact version when it started to work is - unknown to me). - - After a transfer, you just set new options in the handle and make another - transfer. This will make libcurl to re-use the same connection if it can. |