| _ _ ____ _ |
| ___| | | | _ \| | |
| / __| | | | |_) | | |
| | (__| |_| | _ <| |___ |
| \___|\___/|_| \_\_____| |
| |
| Known Bugs |
| |
| These are problems and bugs known to exist at the time of this release. Feel |
| free to join in and help us correct one or more of these! Also be sure to |
| check the changelog of the current development status, as one or more of these |
| problems may have been fixed or changed somewhat since this was written! |
| |
| 1. HTTP |
| 1.1 CURLFORM_CONTENTLEN in an array |
| 1.2 Disabling HTTP Pipelining |
| 1.3 STARTTRANSFER time is wrong for HTTP POSTs |
| 1.4 multipart formposts file name encoding |
| 1.5 Expect-100 meets 417 |
| 1.6 Unnecessary close when 401 received waiting for 100 |
| 1.9 HTTP/2 frames while in the connection pool kill reuse |
| 1.10 Strips trailing dot from host name |
| 1.11 CURLOPT_SEEKFUNCTION not called with CURLFORM_STREAM |
| |
| 2. TLS |
| 2.1 CURLINFO_SSL_VERIFYRESULT has limited support |
| 2.2 DER in keychain |
| 2.3 GnuTLS backend skips really long certificate fields |
| 2.4 DarwinSSL won't import PKCS#12 client certificates without a password |
| |
| 3. Email protocols |
| 3.1 IMAP SEARCH ALL truncated response |
| 3.2 No disconnect command |
| 3.3 SMTP to multiple recipients |
| 3.4 POP3 expects "CRLF.CRLF" eob for some single-line responses |
| |
| 4. Command line |
| 4.1 -J with %-encoded file nameas |
| 4.2 -J with -C - fails |
| 4.3 --retry and transfer timeouts |
| |
| 5. Build and portability issues |
| 5.1 Windows Borland compiler |
| 5.2 curl-config --libs contains private details |
| 5.4 AIX shared build with c-ares fails |
| 5.5 can't handle Unicode arguments in Windows |
| 5.6 cmake support gaps |
| 5.7 Visual Studio project gaps |
| 5.8 configure finding libs in wrong directory |
| 5.9 Utilize Requires.private directives in libcurl.pc |
| |
| 6. Authentication |
| 6.1 NTLM authentication and unicode |
| 6.2 MIT Kerberos for Windows build |
| 6.3 NTLM in system context uses wrong name |
| 6.4 Negotiate and Kerberos V5 need a fake user name |
| |
| 7. FTP |
| 7.1 FTP without or slow 220 response |
| 7.2 FTP with CONNECT and slow server |
| 7.3 FTP with NOBODY and FAILONERROR |
| 7.4 FTP with ACCT |
| 7.5 ASCII FTP |
| 7.6 FTP with NULs in URL parts |
| 7.7 FTP and empty path parts in the URL |
| 7.8 Premature transfer end but healthy control channel |
| |
| 8. TELNET |
| 8.1 TELNET and time limtiations don't work |
| 8.2 Microsoft telnet server |
| |
| 9. SFTP and SCP |
| 9.1 SFTP doesn't do CURLOPT_POSTQUOTE correct |
| |
| 10. SOCKS |
| 10.1 SOCKS proxy connections are done blocking |
| 10.2 SOCKS don't support timeouts |
| 10.3 FTPS over SOCKS |
| 10.4 active FTP over a SOCKS |
| |
| 11. Internals |
| 11.1 Curl leaks .onion hostnames in DNS |
| 11.2 error buffer not set if connection to multiple addresses fails |
| 11.3 c-ares deviates from stock resolver on http://1346569778 |
| 11.4 HTTP test server 'connection-monitor' problems |
| |
| 12. LDAP and OpenLDAP |
| 12.1 OpenLDAP hangs after returning results |
| |
| 13. TCP/IP |
| 13.1 --interface for ipv6 binds to unusable IP address |
| |
| |
| ============================================================================== |
| |
| 1. HTTP |
| |
| 1.1 CURLFORM_CONTENTLEN in an array |
| |
| It is not possible to pass a 64-bit value using CURLFORM_CONTENTLEN with |
| CURLFORM_ARRAY, when compiled on 32-bit platforms that support 64-bit |
| integers. This is because the underlying structure 'curl_forms' uses a dual |
| purpose char* for storing these values in via casting. For more information |
| see the now closed related issue: |
| https://github.com/curl/curl/issues/608 |
| |
| 1.2 Disabling HTTP Pipelining |
| |
| Disabling HTTP Pipelining when there are ongoing transfers can lead to |
| heap corruption and crash. https://curl.haxx.se/bug/view.cgi?id=1411 |
| |
| 1.3 STARTTRANSFER time is wrong for HTTP POSTs |
| |
| Wrong STARTTRANSFER timer accounting for POST requests Timer works fine with |
| GET requests, but while using POST the time for CURLINFO_STARTTRANSFER_TIME |
| is wrong. While using POST CURLINFO_STARTTRANSFER_TIME minus |
| CURLINFO_PRETRANSFER_TIME is near to zero every time. |
| |
| https://github.com/curl/curl/issues/218 |
| https://curl.haxx.se/bug/view.cgi?id=1213 |
| |
| 1.4 multipart formposts file name encoding |
| |
| When creating multipart formposts. The file name part can be encoded with |
| something beyond ascii but currently libcurl will only pass in the verbatim |
| string the app provides. There are several browsers that already do this |
| encoding. The key seems to be the updated draft to RFC2231: |
| https://tools.ietf.org/html/draft-reschke-rfc2231-in-http-02 |
| |
| 1.5 Expect-100 meets 417 |
| |
| If an upload using Expect: 100-continue receives an HTTP 417 response, it |
| ought to be automatically resent without the Expect:. A workaround is for |
| the client application to redo the transfer after disabling Expect:. |
| https://curl.haxx.se/mail/archive-2008-02/0043.html |
| |
| 1.6 Unnecessary close when 401 received waiting for 100 |
| |
| libcurl closes the connection if an HTTP 401 reply is received while it is |
| waiting for the the 100-continue response. |
| https://curl.haxx.se/mail/lib-2008-08/0462.html |
| |
| 1.9 HTTP/2 frames while in the connection pool kill reuse |
| |
| If the server sends HTTP/2 frames (like for example an HTTP/2 PING frame) to |
| curl while the connection is held in curl's connection pool, the socket will |
| be found readable when considered for reuse and that makes curl think it is |
| dead and then it will be closed and a new connection gets created instead. |
| |
| This is *best* fixed by adding monitoring to connections while they are kept |
| in the pool so that pings can be responded to appropriately. |
| |
| 1.10 Strips trailing dot from host name |
| |
| When given a URL with a trailing dot for the host name part: |
| "https://example.com./", libcurl will strip off the dot and use the name |
| without a dot internally and send it dot-less in HTTP Host: headers and in |
| the TLS SNI field. |
| |
| The HTTP part violates RFC 7230 section 5.4 but the SNI part is accordance |
| with RFC 6066 section 3. |
| |
| URLs using these trailing dots are very rare in the wild and we have not seen |
| or gotten any real-world problems with such URLs reported. The popular |
| browsers seem to have stayed with not stripping the dot for both uses (thus |
| they violate RFC 6066 instead of RFC 7230). |
| |
| Daniel took the discussion to the HTTPbis mailing list in March 2016: |
| https://lists.w3.org/Archives/Public/ietf-http-wg/2016JanMar/0430.html but |
| there was not major rush or interest to fix this. The impression I get is |
| that most HTTP people rather not rock the boat now and instead prioritize web |
| compatibility rather than to strictly adhere to these RFCs. |
| |
| Our current approach allows a knowing client to send a custom HTTP header |
| with the dot added. |
| |
| It can also be noted that while adding a trailing dot to the host name in |
| most (all?) cases will make the name resolve to the same set of IP addresses, |
| many HTTP servers will not happily accept the trailing dot there unless that |
| has been specifically configured to be a fine virtual host. |
| |
| If URLs with trailing dots for host names become more popular or even just |
| used more than for just plain fun experiments, I'm sure we will have reason |
| to go back and reconsider. |
| |
| See https://github.com/curl/curl/issues/716 for the discussion. |
| |
| 1.11 CURLOPT_SEEKFUNCTION not called with CURLFORM_STREAM |
| |
| I'm using libcurl to POST form data using a FILE* with the CURLFORM_STREAM |
| option of curl_formadd(). I've noticed that if the connection drops at just |
| the right time, the POST is reattempted without the data from the file. It |
| seems like the file stream position isn't getting reset to the beginning of |
| the file. I found the CURLOPT_SEEKFUNCTION option and set that with a |
| function that performs an fseek() on the FILE*. However, setting that didn't |
| seem to fix the issue or even get called. See |
| https://github.com/curl/curl/issues/768 |
| |
| |
| 2. TLS |
| |
| 2.1 CURLINFO_SSL_VERIFYRESULT has limited support |
| |
| CURLINFO_SSL_VERIFYRESULT is only implemented for the OpenSSL and NSS |
| backends, so relying on this information in a generic app is flaky. |
| |
| 2.2 DER in keychain |
| |
| Curl doesn't recognize certificates in DER format in keychain, but it works |
| with PEM. https://curl.haxx.se/bug/view.cgi?id=1065 |
| |
| 2.3 GnuTLS backend skips really long certificate fields |
| |
| libcurl calls gnutls_x509_crt_get_dn() with a fixed buffer size and if the |
| field is too long in the cert, it'll just return an error and the field will |
| be displayed blank. |
| |
| 2.4 DarwinSSL won't import PKCS#12 client certificates without a password |
| |
| libcurl calls SecPKCS12Import with the PKCS#12 client certificate, but that |
| function rejects certificates that do not have a password. |
| https://github.com/curl/curl/issues/1308 |
| |
| |
| 3. Email protocols |
| |
| 3.1 IMAP SEARCH ALL truncated response |
| |
| IMAP "SEARCH ALL" truncates output on large boxes. "A quick search of the |
| code reveals that pingpong.c contains some truncation code, at line 408, when |
| it deems the server response to be too large truncating it to 40 characters" |
| https://curl.haxx.se/bug/view.cgi?id=1366 |
| |
| 3.2 No disconnect command |
| |
| The disconnect commands (LOGOUT and QUIT) may not be sent by IMAP, POP3 and |
| SMTP if a failure occurs during the authentication phase of a connection. |
| |
| 3.3 SMTP to multiple recipients |
| |
| When sending data to multiple recipients, curl will abort and return failure |
| if one of the recipients indicate failure (on the "RCPT TO" |
| command). Ordinary mail programs would proceed and still send to the ones |
| that can receive data. This is subject for change in the future. |
| https://curl.haxx.se/bug/view.cgi?id=1116 |
| |
| 3.4 POP3 expects "CRLF.CRLF" eob for some single-line responses |
| |
| You have to tell libcurl not to expect a body, when dealing with one line |
| response commands. Please see the POP3 examples and test cases which show |
| this for the NOOP and DELE commands. https://curl.haxx.se/bug/?i=740 |
| |
| |
| 4. Command line |
| |
| 4.1 -J with %-encoded file nameas |
| |
| -J/--remote-header-name doesn't decode %-encoded file names. RFC6266 details |
| how it should be done. The can of worm is basically that we have no charset |
| handling in curl and ascii >=128 is a challenge for us. Not to mention that |
| decoding also means that we need to check for nastiness that is attempted, |
| like "../" sequences and the like. Probably everything to the left of any |
| embedded slashes should be cut off. |
| https://curl.haxx.se/bug/view.cgi?id=1294 |
| |
| 4.2 -J with -C - fails |
| |
| When using -J (with -O), automatically resumed downloading together with "-C |
| -" fails. Without -J the same command line works! This happens because the |
| resume logic is worked out before the target file name (and thus its |
| pre-transfer size) has been figured out! |
| https://curl.haxx.se/bug/view.cgi?id=1169 |
| |
| 4.3 --retry and transfer timeouts |
| |
| If using --retry and the transfer timeouts (possibly due to using -m or |
| -y/-Y) the next attempt doesn't resume the transfer properly from what was |
| downloaded in the previous attempt but will truncate and restart at the |
| original position where it was at before the previous failed attempt. See |
| https://curl.haxx.se/mail/lib-2008-01/0080.html and Mandriva bug report |
| https://qa.mandriva.com/show_bug.cgi?id=22565 |
| |
| |
| 5. Build and portability issues |
| |
| 5.1 Windows Borland compiler |
| |
| When building with the Windows Borland compiler, it fails because the "tlib" |
| tool doesn't support hyphens (minus signs) in file names and we have such in |
| the build. https://curl.haxx.se/bug/view.cgi?id=1222 |
| |
| 5.2 curl-config --libs contains private details |
| |
| "curl-config --libs" will include details set in LDFLAGS when configure is |
| run that might be needed only for building libcurl. Further, curl-config |
| --cflags suffers from the same effects with CFLAGS/CPPFLAGS. |
| |
| 5.4 AIX shared build with c-ares fails |
| |
| curl version 7.12.2 fails on AIX if compiled with --enable-ares. The |
| workaround is to combine --enable-ares with --disable-shared |
| |
| 5.5 can't handle Unicode arguments in Windows |
| |
| If a URL or filename can't be encoded using the user's current codepage then |
| it can only be encoded properly in the Unicode character set. Windows uses |
| UTF-16 encoding for Unicode and stores it in wide characters, however curl |
| and libcurl are not equipped for that at the moment. And, except for Cygwin, |
| Windows can't use UTF-8 as a locale. |
| |
| https://curl.haxx.se/bug/?i=345 |
| https://curl.haxx.se/bug/?i=731 |
| |
| 5.6 cmake support gaps |
| |
| The cmake build setup lacks several features that the autoconf build |
| offers. This includes: |
| |
| - use of correct soname for the shared library build |
| - support for several TLS backends are missing |
| - the unit tests cause link failures in regular non-static builds |
| - no nghttp2 check |
| |
| 5.7 Visual Studio project gaps |
| |
| The Visual Studio projects lack some features that the autoconf and nmake |
| builds offer, such as the following: |
| |
| - support for zlib and nghttp2 |
| - use of static runtime libraries |
| - add the test suite components |
| |
| In addition to this the following could be implemented: |
| |
| - support for other development IDEs |
| - add PATH environment variables for third-party DLLs |
| |
| 5.8 configure finding libs in wrong directory |
| |
| When the configure script checks for third-party libraries, it adds those |
| directories to the LDFLAGS variable and then tries linking to see if it |
| works. When successful, the found directory is kept in the LDFLAGS variable |
| when the script continues to execute and do more tests and possibly check for |
| more libraries. |
| |
| This can make subsequent checks for libraries wrongly detect another |
| installation in a directory that was previously added to LDFLAGS by another |
| library check! |
| |
| A possibly better way to do these checks would be to keep the pristine LDFLAGS |
| even after successful checks and instead add those verified paths to a |
| separate variable that only after all library checks have been performed gets |
| appended to LDFLAGS. |
| |
| 5.9 Utilize Requires.private directives in libcurl.pc |
| |
| https://github.com/curl/curl/issues/864 |
| |
| 6. Authentication |
| |
| 6.1 NTLM authentication and unicode |
| |
| NTLM authentication involving unicode user name or password only works |
| properly if built with UNICODE defined together with the WinSSL/schannel |
| backend. The original problem was mentioned in: |
| https://curl.haxx.se/mail/lib-2009-10/0024.html |
| https://curl.haxx.se/bug/view.cgi?id=896 |
| |
| The WinSSL/schannel version verified to work as mentioned in |
| https://curl.haxx.se/mail/lib-2012-07/0073.html |
| |
| 6.2 MIT Kerberos for Windows build |
| |
| libcurl fails to build with MIT Kerberos for Windows (KfW) due to KfW's |
| library header files exporting symbols/macros that should be kept private to |
| the KfW library. See ticket #5601 at https://krbdev.mit.edu/rt/ |
| |
| 6.3 NTLM in system context uses wrong name |
| |
| NTLM authentication using SSPI (on Windows) when (lib)curl is running in |
| "system context" will make it use wrong(?) user name - at least when compared |
| to what winhttp does. See https://curl.haxx.se/bug/view.cgi?id=535 |
| |
| 6.4 Negotiate and Kerberos V5 need a fake user name |
| |
| In order to get Negotiate (SPNEGO) authentication to work in HTTP or Kerberos |
| V5 in the e-mail protocols, you need to provide a (fake) user name (this |
| concerns both curl and the lib) because the code wrongly only considers |
| authentication if there's a user name provided by setting |
| conn->bits.user_passwd in url.c https://curl.haxx.se/bug/view.cgi?id=440 How? |
| https://curl.haxx.se/mail/lib-2004-08/0182.html A possible solution is to |
| either modify this variable to be set or introduce a variable such as |
| new conn->bits.want_authentication which is set when any of the authentication |
| options are set. |
| |
| |
| 7. FTP |
| |
| 7.1 FTP without or slow 220 response |
| |
| If a connection is made to a FTP server but the server then just never sends |
| the 220 response or otherwise is dead slow, libcurl will not acknowledge the |
| connection timeout during that phase but only the "real" timeout - which may |
| surprise users as it is probably considered to be the connect phase to most |
| people. Brought up (and is being misunderstood) in: |
| https://curl.haxx.se/bug/view.cgi?id=856 |
| |
| 7.2 FTP with CONNECT and slow server |
| |
| When doing FTP over a socks proxy or CONNECT through HTTP proxy and the multi |
| interface is used, libcurl will fail if the (passive) TCP connection for the |
| data transfer isn't more or less instant as the code does not properly wait |
| for the connect to be confirmed. See test case 564 for a first shot at a test |
| case. |
| |
| 7.3 FTP with NOBODY and FAILONERROR |
| |
| It seems sensible to be able to use CURLOPT_NOBODY and CURLOPT_FAILONERROR |
| with FTP to detect if a file exists or not, but it is not working: |
| https://curl.haxx.se/mail/lib-2008-07/0295.html |
| |
| 7.4 FTP with ACCT |
| |
| When doing an operation over FTP that requires the ACCT command (but not when |
| logging in), the operation will fail since libcurl doesn't detect this and |
| thus fails to issue the correct command: |
| https://curl.haxx.se/bug/view.cgi?id=635 |
| |
| 7.5 ASCII FTP |
| |
| FTP ASCII transfers do not follow RFC959. They don't convert the data |
| accordingly (not for sending nor for receiving). RFC 959 section 3.1.1.1 |
| clearly describes how this should be done: |
| |
| The sender converts the data from an internal character representation to |
| the standard 8-bit NVT-ASCII representation (see the Telnet |
| specification). The receiver will convert the data from the standard |
| form to his own internal form. |
| |
| Since 7.15.4 at least line endings are converted. |
| |
| 7.6 FTP with NULs in URL parts |
| |
| FTP URLs passed to curl may contain NUL (0x00) in the RFC 1738 <user>, |
| <password>, and <fpath> components, encoded as "%00". The problem is that |
| curl_unescape does not detect this, but instead returns a shortened C string. |
| From a strict FTP protocol standpoint, NUL is a valid character within RFC |
| 959 <string>, so the way to handle this correctly in curl would be to use a |
| data structure other than a plain C string, one that can handle embedded NUL |
| characters. From a practical standpoint, most FTP servers would not |
| meaningfully support NUL characters within RFC 959 <string>, anyway (e.g., |
| Unix pathnames may not contain NUL). |
| |
| 7.7 FTP and empty path parts in the URL |
| |
| libcurl ignores empty path parts in FTP URLs, whereas RFC1738 states that |
| such parts should be sent to the server as 'CWD ' (without an argument). The |
| only exception to this rule, is that we knowingly break this if the empty |
| part is first in the path, as then we use the double slashes to indicate that |
| the user wants to reach the root dir (this exception SHALL remain even when |
| this bug is fixed). |
| |
| 7.8 Premature transfer end but healthy control channel |
| |
| When 'multi_done' is called before the transfer has been completed the normal |
| way, it is considered a "premature" transfer end. In this situation, libcurl |
| closes the connection assuming it doesn't know the state of the connection so |
| it can't be reused for subsequent requests. |
| |
| With FTP however, this isn't necessarily true but there are a bunch of |
| situations (listed in the ftp_done code) where it *could* keep the connection |
| alive even in this situation - but the current code doesn't. Fixing this would |
| allow libcurl to reuse FTP connections better. |
| |
| 8. TELNET |
| |
| 8.1 TELNET and time limtiations don't work |
| |
| When using telnet, the time limitation options don't work. |
| https://curl.haxx.se/bug/view.cgi?id=846 |
| |
| 8.2 Microsoft telnet server |
| |
| There seems to be a problem when connecting to the Microsoft telnet server. |
| https://curl.haxx.se/bug/view.cgi?id=649 |
| |
| |
| 9. SFTP and SCP |
| |
| 9.1 SFTP doesn't do CURLOPT_POSTQUOTE correct |
| |
| When libcurl sends CURLOPT_POSTQUOTE commands when connected to a SFTP server |
| using the multi interface, the commands are not being sent correctly and |
| instead the connection is "cancelled" (the operation is considered done) |
| prematurely. There is a half-baked (busy-looping) patch provided in the bug |
| report but it cannot be accepted as-is. See |
| https://curl.haxx.se/bug/view.cgi?id=748 |
| |
| |
| 10. SOCKS |
| |
| 10.1 SOCKS proxy connections are done blocking |
| |
| Both SOCKS5 and SOCKS4 proxy connections are done blocking, which is very bad |
| when used with the multi interface. |
| |
| 10.2 SOCKS don't support timeouts |
| |
| The SOCKS4 connection codes don't properly acknowledge (connect) timeouts. |
| According to bug #1556528, even the SOCKS5 connect code does not do it right: |
| https://curl.haxx.se/bug/view.cgi?id=604 |
| |
| When connecting to a SOCK proxy, the (connect) timeout is not properly |
| acknowledged after the actual TCP connect (during the SOCKS "negotiate" |
| phase). |
| |
| 10.3 FTPS over SOCKS |
| |
| libcurl doesn't support FTPS over a SOCKS proxy. |
| |
| 10.4 active FTP over a SOCKS |
| |
| libcurl doesn't support active FTP over a SOCKS proxy |
| |
| |
| 11. Internals |
| |
| 11.1 Curl leaks .onion hostnames in DNS |
| |
| Curl sends DNS requests for hostnames with a .onion TLD. This leaks |
| information about what the user is attempting to access, and violates this |
| requirement of RFC7686: https://tools.ietf.org/html/rfc7686 |
| |
| Issue: https://github.com/curl/curl/issues/543 |
| |
| 11.2 error buffer not set if connection to multiple addresses fails |
| |
| If you ask libcurl to resolve a hostname like example.com to IPv6 addresses |
| only. But you only have IPv4 connectivity. libcurl will correctly fail with |
| CURLE_COULDNT_CONNECT. But the error buffer set by CURLOPT_ERRORBUFFER |
| remains empty. Issue: https://github.com/curl/curl/issues/544 |
| |
| 11.3 c-ares deviates from stock resolver on http://1346569778 |
| |
| When using the socket resolvers, that URL becomes: |
| |
| * Rebuilt URL to: http://1346569778/ |
| * Trying 80.67.6.50... |
| |
| but with c-ares it instead says "Could not resolve: 1346569778 (Domain name |
| not found)" |
| |
| See https://github.com/curl/curl/issues/893 |
| |
| 11.4 HTTP test server 'connection-monitor' problems |
| |
| The 'connection-monitor' feature of the sws HTTP test server doesn't work |
| properly if some tests are run in unexpected order. Like 1509 and then 1525. |
| |
| See https://github.com/curl/curl/issues/868 |
| |
| |
| 12. LDAP and OpenLDAP |
| |
| 12.1 OpenLDAP hangs after returning results |
| |
| By configuration defaults, openldap automatically chase referrals on |
| secondary socket descriptors. The OpenLDAP backend is asynchronous and thus |
| should monitor all socket descriptors involved. Currently, these secondary |
| descriptors are not monitored, causing openldap library to never receive |
| data from them. |
| |
| As a temporary workaround, disable referrals chasing by configuration. |
| |
| The fix is not easy: proper automatic referrals chasing requires a |
| synchronous bind callback and monitoring an arbitrary number of socket |
| descriptors for a single easy handle (currently limited to 5). |
| |
| Generic LDAP is synchronous: OK. |
| |
| See https://github.com/curl/curl/issues/622 and |
| https://curl.haxx.se/mail/lib-2016-01/0101.html |
| |
| |
| 13. TCP/IP |
| |
| 13.1 --interface for ipv6 binds to unusable IP address |
| |
| Since IPv6 provides a lot of addresses with different scope, binding to an |
| IPv6 address needs to take the proper care so that it doesn't bind to a |
| locally scoped address as that is bound to fail. |
| |
| https://github.com/curl/curl/issues/686 |