ac6264366f
- tool_bname: scope an include. - `endif` comments. - Markdown fixes. - comment tidy-ups. - whitespace, newlines, indent. Closes #20309
19 KiB
Known bugs intro
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.
TLS
IMAPS connection fails with Rustls error
Access violation sending client cert with Schannel
When using Schannel to do client certs, curl sets PKCS12_NO_PERSIST_KEY to
avoid leaking the private key into the filesystem. Unfortunately that flag
instead seems to trigger a crash.
See curl issue 17626
Client cert handling with Issuer DN differs between backends
When the specified client certificate does not match any of the
server-specified DN fields, the OpenSSL and GnuTLS backends behave
differently. The GitHub discussion may contain a solution.
See curl issue 1411
Client cert (MTLS) issues with Schannel
See curl issue 3145
Schannel TLS 1.2 handshake bug in old Windows versions
In old versions of Windows such as 7 and 8.1 the Schannel TLS 1.2 handshake implementation likely has a bug that can rarely cause the key exchange to fail, resulting in error SEC_E_BUFFER_TOO_SMALL or SEC_E_MESSAGE_ALTERED.
CURLOPT_CERTINFO results in CURLE_OUT_OF_MEMORY with Schannel
mbedTLS and CURLE_AGAIN handling
Email protocols
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.se/bug/view.cgi?id=1366
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.
AUTH PLAIN for SMTP is not working on all servers
Specifying --login-options AUTH=PLAIN on the command line does not seem to
work correctly.
See curl issue 4080
APOP authentication fails on POP3
See curl issue 10073
POP3 issue when reading small chunks
CURL_DBG_SOCK_RMAX=4 ./runtests.pl -v 982
See curl issue 12063
Command line
-T /dev/stdin may upload with an incorrect content length
-T stats the path to figure out its size in bytes to use it as
Content-Length if it is a regular file.
The problem with that is that on BSD and some other UNIX systems (not Linux), open(path) may not give you a file descriptor with a 0 offset from the start of the file.
See curl issue 12177
-T - always uploads chunked
When the < shell operator is used. curl should realize that stdin is a
regular file in this case, and that it can do a non-chunked upload, like it
would do if you used -T file.
See curl issue 12171
Build and portability issues
OS400 port requires deprecated IBM library
curl for OS400 requires QADRT to build, which provides ASCII wrappers for
libc/POSIX functions in the ILE, but IBM no longer supports or even offers
this library to download.
See curl issue 5176
curl-config --libs contains private details
curl-config --libs 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.
LDFLAGS passed too late making libs linked incorrectly
Compiling latest curl on HP-UX and linking against a custom OpenSSL (which is
on the default loader/linker path), fails because the generated Makefile has
LDFLAGS passed on after LIBS.
See curl issue 14893
Cygwin: make install installs curl-config.1 twice
flaky CI builds
We run many CI builds for each commit and PR on GitHub, and especially a number of the Windows builds are flaky. This means that we rarely get all CI builds go green and complete without errors. This is unfortunate as it makes us sometimes miss actual build problems and it is surprising to newcomers to the project who (rightfully) do not expect this.
See curl issue 6972
long paths are not fully supported on Windows
curl on Windows cannot access long paths (paths longer than 260 characters).
However, as a workaround, the Windows path prefix \\?\ which disables all
path interpretation may work to allow curl to access the path. For example:
\\?\c:\longpath.
See curl issue 8361
Unicode on Windows
Passing in a Unicode filename with -o:
Passing in Unicode character with -d:
Windows Unicode builds use the home directory in current locale.
The Windows Unicode builds of curl use the current locale, but expect Unicode UTF-8 encoded paths for internal use such as open, access and stat. The user's home directory is retrieved via curl_getenv in the current locale and not as UTF-8 encoded Unicode.
See curl pull request 7252 and curl pull request 7281
Cannot handle Unicode arguments in non-Unicode builds on Windows
If a URL or filename cannot be encoded using the user's current code page 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 except when built with _UNICODE and UNICODE defined. Except for Cygwin, Windows cannot use UTF-8 as a locale.
https://curl.se/bug/?i=345 https://curl.se/bug/?i=731 https://curl.se/bug/?i=3747
NTLM authentication and Unicode
NTLM authentication involving Unicode username or password only works properly if built with UNICODE defined together with the Schannel backend. The original problem was mentioned in: https://curl.se/mail/lib-2009-10/0024.html and https://curl.se/bug/view.cgi?id=896
The Schannel version verified to work as mentioned in https://curl.se/mail/lib-2012-07/0073.html
Authentication
Digest auth-int for PUT/POST
We do not support auth-int for Digest using PUT or POST
MIT Kerberos for Windows build
libcurl fails to build with MIT Kerberos for Windows (KfW) due to its
library header files exporting symbols/macros that should be kept private to
the library.
NTLM in system context uses wrong name
NTLM authentication using SSPI (on Windows) when (lib)curl is running in
"system context" makes it use wrong(?) username - at least when compared to
what winhttp does. See https://curl.se/bug/view.cgi?id=535
NTLM does not support password with Unicode 'SECTION SIGN' character
Code point: U+00A7
https://en.wikipedia.org/wiki/Section_sign curl issue 2120
libcurl can fail to try alternatives with --proxy-any
When connecting via a proxy using --proxy-any, a failure to establish an
authentication causes libcurl to abort trying other options if the failed
method has a higher preference than the alternatives. As an example,
--proxy-any against a proxy which advertise Negotiate and NTLM, but which
fails to set up Kerberos authentication does not proceed to try authentication
using NTLM.
Do not clear digest for single realm
SHA-256 digest not supported in Windows SSPI builds
Windows builds of curl that have SSPI enabled use the native Windows API calls
to create authentication strings. The call to InitializeSecurityContext fails
with SEC_E_QOP_NOT_SUPPORTED which causes curl to fail with
CURLE_AUTH_ERROR.
Microsoft does not document supported digest algorithms and that SEC_E error
code is not a documented error for InitializeSecurityContext (digest).
curl never completes Negotiate over HTTP
Apparently it is not working correctly...?
See curl issue 5235
Negotiate on Windows fails
When using --negotiate (or NTLM) with curl on Windows, SSL/TLS handshake
fails despite having a valid kerberos ticket cached. Works without any issue
in Unix/Linux.
Negotiate authentication against Hadoop
FTP
FTP with ACCT
When doing an operation over FTP that requires the ACCT command (but not when
logging in), the operation fails since libcurl does not detect this and thus
fails to issue the correct command: https://curl.se/bug/view.cgi?id=635
FTPS server compatibility on Windows with Schannel
FTPS is not widely used with the Schannel TLS backend and so there may be more bugs compared to other TLS backends such as OpenSSL. In the past users have reported hanging and failed connections. It is likely some changes to curl since then fixed the issues. None of the reported issues can be reproduced any longer.
If you encounter an issue connecting to your server via FTPS with the latest curl and Schannel then please search for open issues or file a new issue.
SFTP and SCP
SFTP does not do CURLOPT_POSTQUOTE correct
When libcurl sends CURLOPT_POSTQUOTE commands when connected to an SFTP
server using the multi interface, the commands are not being sent correctly
and instead the connection is canceled (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.se/bug/view.cgi?id=748
Remote recursive folder creation with SFTP
On this servers, the curl fails to create directories on the remote server
even when the CURLOPT_FTP_CREATE_MISSING_DIRS option is set.
See curl issue 5204
libssh blocking and infinite loop problem
In the SSH_SFTP_INIT state for libssh, the ssh session working mode is set
to blocking mode. If the network is suddenly disconnected during sftp
transmission, curl is stuck, even if curl is configured with a timeout.
Cygwin: "WARNING: UNPROTECTED PRIVATE KEY FILE!"
Running SCP and SFTP tests on Cygwin makes this warning message appear.
Connection
--interface with link-scoped IPv6 address
When you give the --interface option telling curl to use a specific
interface for its outgoing traffic in combination with an IPv6 address in the
URL that uses a link-local scope, curl might pick the wrong address from the
named interface and the subsequent transfer fails.
Example command line:
curl --interface eth0 'http://[fe80:928d:xxff:fexx:xxxx]/'
The fact that the given IP address is link-scoped should probably be used as input to somehow make curl make a better choice for this.
Does not acknowledge getaddrinfo sorting policy
Even if a user edits /etc/gai.conf to prefer IPv4, curl still prefers and
tries IPv6 addresses first.
SOCKS-SSPI discards the security context
After a successful SSPI/GSS-API exchange, the function queries and logs the authenticated username and reports the supported data-protection level, but then immediately deletes the negotiated SSPI security context and frees the credentials before returning. The negotiated context is not stored on the connection and is therefore never used to protect later SOCKS5 traffic.
cannot use absolute Unix domain filename for SOCKS on Windows
curl supports using a Unix domain socket path for speaking SOCKS to a proxy,
by providing a filename in the URL used for -x (CURLOPT_PROXY), but that
path cannot be a proper absolute Windows path with a drive letter etc.
A solution for this probably requires that we add and provide a
--unix-socket (CURLOPT_UNIX_SOCKET_PATH) option alternative for proxy
communication.
See curl issue 19825
Internals
GSSAPI library name + version is missing in curl_version_info()
The struct needs to be expanded and code added to store this info.
See curl issue 13492
error buffer not set if connection to multiple addresses fails
If you ask libcurl to resolve a hostname like example.com to IPv6 addresses
when you only have IPv4 connectivity. libcurl fails with
CURLE_COULDNT_CONNECT, but the error buffer set by CURLOPT_ERRORBUFFER
remains empty. Issue: curl issue 544
HTTP test server 'connection-monitor' problems
The connection-monitor feature of the HTTP test server does not work
properly if some tests are run in unexpected order. Like 1509 and then 1525.
See curl issue 868
Connection information when using TCP Fast Open
CURLINFO_LOCAL_PORT (and possibly a few other) fails when TCP Fast Open is
enabled.
See curl issue 1332 and curl issue 4296
test cases sometimes timeout
Occasionally, one of the tests timeouts. Inexplicably.
See curl issue 13350
CURLOPT_CONNECT_TO does not work for HTTPS proxy
It is unclear if the same option should even cover the proxy connection or if if requires a separate option.
See curl issue 14481
WinIDN test failures
Test 165 disabled when built with WinIDN.
setting a disabled option should return CURLE_NOT_BUILT_IN
When curl has been built with specific features or protocols disabled, setting
such options with curl_easy_setopt() should rather return
CURLE_NOT_BUILT_IN instead of CURLE_UNKNOWN_OPTION to signal the
difference to the application
See curl issue 15472
LDAP
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 curl issue 622 and https://curl.se/mail/lib-2016-01/0101.html
LDAP on Windows does authentication wrong?
LDAP on Windows does not work
A simple curl command line getting ldap://ldap.forumsys.com returns an error
that says no memory !
LDAPS requests to Active Directory server hang
TCP/IP
telnet code does not handle partial writes properly
It probably does not happen too easily because of how slow and infrequent sends are normally performed.
Trying local ports fails on Windows
This makes --local-port [range] to not work since curl cannot properly
detect if a port is already in use, so it tries the first port, uses that and
then subsequently fails anyway if that was actually in use.
CMake
cmake outputs: no version information available
Something in the SONAME generation seems to be wrong in the cmake build.
uses -lpthread instead of Threads::Threads
See curl issue 6166
generated .pc file contains strange entries
The Libs.private field of the generated .pc file contains -lgcc -lgcc_s -lc -lgcc -lgcc_s.
See curl issue 6167
CMake build with MIT Kerberos does not work
Minimum CMake version was bumped in curl 7.71.0 (#5358) Since CMake 3.2
try_compile started respecting the CMAKE_EXE_FLAGS. The code dealing with
MIT Kerberos detection sets few variables to potentially weird mix of space,
and ;-separated flags. It had to blow up at some point. All the CMake checks
that involve compilation are doomed from that point, the configured tree
cannot be built.
Authentication
--aws-sigv4 does not handle multipart/form-data correctly
HTTP/2
HTTP/2 prior knowledge over proxy
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 is found readable when considered for reuse and that makes curl think it is dead and then it is 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.
ENHANCE_YOUR_CALM causes infinite retries
Infinite retries with 2 parallel requests on one connection receiving GOAWAY
with ENHANCE_YOUR_CALM error code.
See curl issue 5119
HTTP/2 + TLS spends a lot of time in recv
It has been observed that by making the speed limit less accurate we could improve this performance. (by reverting db5c9f4f9e0779) Can we find a golden middle ground?
See https://curl.se/mail/lib-2024-05/0026.html and curl issue 13416
HTTP/3
connection migration does not work
quiche: QUIC connection is draining
The transfer ends with error "QUIC connection is draining".
RTSP
Some methods do not support response bodies
The RTSP implementation is written to assume that a number of RTSP methods always get responses without bodies, even though there seems to be no indication in the RFC that this is always the case.