KNOWN_BUGS 42 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775776777778779780781782783784785786787788789790791792793794795796797798799800801802803804805806807808809810811812813814815816817818819820821822823824825826827828829830831832833834835836837838839840841842843844845846847848849850851852853854855856857858859860861862863864865866867868869870871872873874875876877878879880881882883884885886887888889890891892893894895896897898899900901902903904905906907908909910911912913914915916917918919920921922923924925926927928929930931932933934935936937938939940941942943944945946947948949950951952953954955956957958959960961962963964965966967968969970971972973974975976977978979980981982983984985986987988989990991992993994995996997998999100010011002100310041005100610071008100910101011101210131014101510161017101810191020102110221023102410251026102710281029103010311032103310341035103610371038103910401041104210431044104510461047104810491050105110521053105410551056105710581059106010611062106310641065106610671068106910701071107210731074107510761077107810791080108110821083108410851086108710881089109010911092109310941095109610971098109911001101110211031104110511061107110811091110111111121113111411151116111711181119112011211122112311241125112611271128112911301131113211331134113511361137
  1. _ _ ____ _
  2. ___| | | | _ \| |
  3. / __| | | | |_) | |
  4. | (__| |_| | _ <| |___
  5. \___|\___/|_| \_\_____|
  6. Known Bugs
  7. These are problems and bugs known to exist at the time of this release. Feel
  8. free to join in and help us correct one or more of these. Also be sure to
  9. check the changelog of the current development status, as one or more of these
  10. problems may have been fixed or changed somewhat since this was written.
  11. 1. HTTP
  12. 1.2 Multiple methods in a single WWW-Authenticate: header
  13. 1.3 STARTTRANSFER time is wrong for HTTP POSTs
  14. 1.4 multipart formposts file name encoding
  15. 1.5 Expect-100 meets 417
  16. 1.6 Unnecessary close when 401 received waiting for 100
  17. 1.7 Deflate error after all content was received
  18. 1.8 DoH is not used for all name resolves when enabled
  19. 1.11 CURLOPT_SEEKFUNCTION not called with CURLFORM_STREAM
  20. 2. TLS
  21. 2.1 CURLINFO_SSL_VERIFYRESULT has limited support
  22. 2.2 DER in keychain
  23. 2.3 Unable to use PKCS12 certificate with Secure Transport
  24. 2.4 Secure Transport will not import PKCS#12 client certificates without a password
  25. 2.5 Client cert handling with Issuer DN differs between backends
  26. 2.6 CURL_GLOBAL_SSL
  27. 2.7 Client cert (MTLS) issues with Schannel
  28. 2.8 Schannel disable CURLOPT_SSL_VERIFYPEER and verify hostname
  29. 2.9 TLS session cache does not work with TFO
  30. 2.10 Store TLS context per transfer instead of per connection
  31. 2.11 Schannel TLS 1.2 handshake bug in old Windows versions
  32. 2.12 FTPS with Schannel times out file list operation
  33. 2.14 Secure Transport disabling hostname validation also disables SNI
  34. 2.15 Renegotiate from server may cause hang for OpenSSL backend
  35. 3. Email protocols
  36. 3.1 IMAP SEARCH ALL truncated response
  37. 3.2 No disconnect command
  38. 3.3 POP3 expects "CRLF.CRLF" eob for some single-line responses
  39. 3.4 AUTH PLAIN for SMTP is not working on all servers
  40. 4. Command line
  41. 4.1 -J and -O with %-encoded file names
  42. 4.2 -J with -C - fails
  43. 4.3 --retry and transfer timeouts
  44. 5. Build and portability issues
  45. 5.1 OS400 port requires deprecated IBM library
  46. 5.2 curl-config --libs contains private details
  47. 5.3 curl compiled on OSX 10.13 failed to run on OSX 10.10
  48. 5.4 Build with statically built dependency
  49. 5.5 cannot handle Unicode arguments in non-Unicode builds on Windows
  50. 5.6 make distclean loops forever
  51. 5.7 Visual Studio project gaps
  52. 5.8 configure finding libs in wrong directory
  53. 5.9 Utilize Requires.private directives in libcurl.pc
  54. 5.10 curl hangs on SMB upload over stdin
  55. 5.11 configure --with-gssapi with Heimdal is ignored on macOS
  56. 5.12 flaky Windows CI builds
  57. 6. Authentication
  58. 6.1 NTLM authentication and unicode
  59. 6.2 MIT Kerberos for Windows build
  60. 6.3 NTLM in system context uses wrong name
  61. 6.4 Negotiate and Kerberos V5 need a fake user name
  62. 6.5 NTLM does not support password with § character
  63. 6.6 libcurl can fail to try alternatives with --proxy-any
  64. 6.7 Do not clear digest for single realm
  65. 6.8 RTSP authentication breaks without redirect support
  66. 6.9 SHA-256 digest not supported in Windows SSPI builds
  67. 6.10 curl never completes Negotiate over HTTP
  68. 6.11 Negotiate on Windows fails
  69. 6.12 cannot use Secure Transport with Crypto Token Kit
  70. 7. FTP
  71. 7.1 FTP without or slow 220 response
  72. 7.2 FTP with CONNECT and slow server
  73. 7.3 FTP with NOBODY and FAILONERROR
  74. 7.4 FTP with ACCT
  75. 7.5 ASCII FTP
  76. 7.6 FTP with NULs in URL parts
  77. 7.7 FTP and empty path parts in the URL
  78. 7.8 Premature transfer end but healthy control channel
  79. 7.9 Passive transfer tries only one IP address
  80. 7.10 FTPS needs session reuse
  81. 7.11 FTPS upload data loss with TLS 1.3
  82. 8. TELNET
  83. 8.1 TELNET and time limitations do not work
  84. 8.2 Microsoft telnet server
  85. 9. SFTP and SCP
  86. 9.1 SFTP does not do CURLOPT_POSTQUOTE correct
  87. 9.2 wolfssh: publickey auth does not work
  88. 9.3 Remote recursive folder creation with SFTP
  89. 10. SOCKS
  90. 10.3 FTPS over SOCKS
  91. 10.4 active FTP over a SOCKS
  92. 11. Internals
  93. 11.1 Curl leaks .onion hostnames in DNS
  94. 11.2 error buffer not set if connection to multiple addresses fails
  95. 11.3 Disconnects do not do verbose
  96. 11.4 HTTP test server 'connection-monitor' problems
  97. 11.5 Connection information when using TCP Fast Open
  98. 11.7 signal-based resolver timeouts
  99. 11.8 DoH leaks memory after followlocation
  100. 11.9 DoH does not inherit all transfer options
  101. 11.10 Blocking socket operations in non-blocking API
  102. 11.11 A shared connection cache is not thread-safe
  103. 11.12 'no_proxy' string-matches IPv6 numerical addresses
  104. 11.13 wakeup socket disconnect causes havoc
  105. 11.14 Multi perform hangs waiting for threaded resolver
  106. 11.15 CURLOPT_OPENSOCKETPAIRFUNCTION is missing
  107. 11.16 libcurl uses renames instead of locking for atomic operations
  108. 12. LDAP
  109. 12.1 OpenLDAP hangs after returning results
  110. 12.2 LDAP on Windows does authentication wrong?
  111. 12.3 LDAP on Windows does not work
  112. 12.4 LDAPS with NSS is slow
  113. 13. TCP/IP
  114. 13.1 --interface for ipv6 binds to unusable IP address
  115. 13.2 Trying local ports fails on Windows
  116. 14. DICT
  117. 14.1 DICT responses show the underlying protocol
  118. 15. CMake
  119. 15.1 use correct SONAME
  120. 15.2 support build with GnuTLS
  121. 15.3 unusable tool_hugehelp.c with MinGW
  122. 15.4 build docs/curl.1
  123. 15.5 build on Linux links libcurl to libdl
  124. 15.6 uses -lpthread instead of Threads::Threads
  125. 15.7 generated .pc file contains strange entries
  126. 15.8 libcurl.pc uses absolute library paths
  127. 15.9 cert paths autodetected when cross-compiling
  128. 15.10 libpsl is not supported
  129. 15.11 ExternalProject_Add does not set CURL_CA_PATH
  130. 15.12 cannot enable LDAPS on Windows
  131. 15.13 CMake build with MIT Kerberos does not work
  132. 16. Applications
  133. 17. HTTP/2
  134. 17.1 Excessive HTTP/2 packets with TCP_NODELAY
  135. 17.2 HTTP/2 frames while in the connection pool kill reuse
  136. 17.3 ENHANCE_YOUR_CALM causes infinite retries
  137. 17.4 Connection failures with parallel HTTP/2
  138. 17.5 HTTP/2 connections through HTTPS proxy frequently stall
  139. 18. HTTP/3
  140. 18.1 If the HTTP/3 server closes connection during upload curl hangs
  141. 18.2 Transfer closed with n bytes remaining to read
  142. 18.4 timeout when reusing a http3 connection
  143. 18.9 connection migration does not work
  144. ==============================================================================
  145. 1. HTTP
  146. 1.2 Multiple methods in a single WWW-Authenticate: header
  147. The HTTP responses headers WWW-Authenticate: can provide information about
  148. multiple authentication methods as multiple headers or as several methods
  149. within a single header. The latter way, several methods in the same physical
  150. line, is not supported by libcurl's parser. (For no good reason.)
  151. 1.3 STARTTRANSFER time is wrong for HTTP POSTs
  152. Wrong STARTTRANSFER timer accounting for POST requests Timer works fine with
  153. GET requests, but while using POST the time for CURLINFO_STARTTRANSFER_TIME
  154. is wrong. While using POST CURLINFO_STARTTRANSFER_TIME minus
  155. CURLINFO_PRETRANSFER_TIME is near to zero every time.
  156. https://github.com/curl/curl/issues/218
  157. https://curl.se/bug/view.cgi?id=1213
  158. 1.4 multipart formposts file name encoding
  159. When creating multipart formposts. The file name part can be encoded with
  160. something beyond ascii but currently libcurl will only pass in the verbatim
  161. string the app provides. There are several browsers that already do this
  162. encoding. The key seems to be the updated draft to RFC2231:
  163. https://datatracker.ietf.org/doc/html/draft-reschke-rfc2231-in-http-02
  164. 1.5 Expect-100 meets 417
  165. If an upload using Expect: 100-continue receives an HTTP 417 response, it
  166. ought to be automatically resent without the Expect:. A workaround is for
  167. the client application to redo the transfer after disabling Expect:.
  168. https://curl.se/mail/archive-2008-02/0043.html
  169. 1.6 Unnecessary close when 401 received waiting for 100
  170. libcurl closes the connection if an HTTP 401 reply is received while it is
  171. waiting for the 100-continue response.
  172. https://curl.se/mail/lib-2008-08/0462.html
  173. 1.7 Deflate error after all content was received
  174. There's a situation where we can get an error in an HTTP response that is
  175. compressed, when that error is detected after all the actual body contents
  176. have been received and delivered to the application. This is tricky, but is
  177. ultimately a broken server.
  178. See https://github.com/curl/curl/issues/2719
  179. 1.8 DoH is not used for all name resolves when enabled
  180. Even if DoH is specified to be used, there are some name resolves that are
  181. done without it. This should be fixed. When the internal function
  182. `Curl_resolver_wait_resolv()` is called, it does not use DoH to complete the
  183. resolve as it otherwise should.
  184. See https://github.com/curl/curl/pull/3857 and
  185. https://github.com/curl/curl/pull/3850
  186. 1.11 CURLOPT_SEEKFUNCTION not called with CURLFORM_STREAM
  187. When using libcurl to POST form data using a FILE* with the CURLFORM_STREAM
  188. option of curl_formadd(). I notice that if the connection drops at just the
  189. right time, the POST is reattempted without the data from the file. It seems
  190. like the file stream position is not getting reset to the beginning of the
  191. file. I found the CURLOPT_SEEKFUNCTION option and set that with a function
  192. that performs an fseek() on the FILE*. However, setting that did not seem to
  193. fix the issue or even get called. See https://github.com/curl/curl/issues/768
  194. 2. TLS
  195. 2.1 CURLINFO_SSL_VERIFYRESULT has limited support
  196. CURLINFO_SSL_VERIFYRESULT is only implemented for the OpenSSL, NSS and
  197. GnuTLS backends, so relying on this information in a generic app is flaky.
  198. 2.2 DER in keychain
  199. Curl does not recognize certificates in DER format in keychain, but it works
  200. with PEM. https://curl.se/bug/view.cgi?id=1065
  201. 2.3 Unable to use PKCS12 certificate with Secure Transport
  202. See https://github.com/curl/curl/issues/5403
  203. 2.4 Secure Transport will not import PKCS#12 client certificates without a password
  204. libcurl calls SecPKCS12Import with the PKCS#12 client certificate, but that
  205. function rejects certificates that do not have a password.
  206. https://github.com/curl/curl/issues/1308
  207. 2.5 Client cert handling with Issuer DN differs between backends
  208. When the specified client certificate does not match any of the
  209. server-specified DNs, the OpenSSL and GnuTLS backends behave differently.
  210. The github discussion may contain a solution.
  211. See https://github.com/curl/curl/issues/1411
  212. 2.6 CURL_GLOBAL_SSL
  213. Since libcurl 7.57.0, the flag CURL_GLOBAL_SSL is a no-op. The change was
  214. merged in https://github.com/curl/curl/commit/d661b0afb571a
  215. It was removed since it was
  216. A) never clear for applications on how to deal with init in the light of
  217. different SSL backends (the option was added back in the days when life
  218. was simpler)
  219. B) multissl introduced dynamic switching between SSL backends which
  220. emphasized (A) even more
  221. C) libcurl uses some TLS backend functionality even for non-TLS functions (to
  222. get "good" random) so applications trying to avoid the init for
  223. performance reasons would do wrong anyway
  224. D) not documented carefully so all this mostly just happened to work
  225. for some users
  226. However, in spite of the problems with the feature, there were some users who
  227. apparently depended on this feature and who now claim libcurl is broken for
  228. them. The fix for this situation is not obvious as a downright revert of the
  229. patch is totally ruled out due to those reasons above.
  230. https://github.com/curl/curl/issues/2276
  231. 2.7 Client cert (MTLS) issues with Schannel
  232. See https://github.com/curl/curl/issues/3145
  233. 2.8 Schannel disable CURLOPT_SSL_VERIFYPEER and verify hostname
  234. This seems to be a limitation in the underlying Schannel API.
  235. https://github.com/curl/curl/issues/3284
  236. 2.9 TLS session cache does not work with TFO
  237. See https://github.com/curl/curl/issues/4301
  238. 2.10 Store TLS context per transfer instead of per connection
  239. The GnuTLS `backend->cred` and the OpenSSL `backend->ctx` data and their
  240. proxy versions (and possibly other TLS backends), could be better moved to be
  241. stored in the Curl_easy handle instead of in per connection so that a single
  242. transfer that makes multiple connections can reuse the context and reduce
  243. memory consumption.
  244. https://github.com/curl/curl/issues/5102
  245. 2.11 Schannel TLS 1.2 handshake bug in old Windows versions
  246. In old versions of Windows such as 7 and 8.1 the Schannel TLS 1.2 handshake
  247. implementation likely has a bug that can rarely cause the key exchange to
  248. fail, resulting in error SEC_E_BUFFER_TOO_SMALL or SEC_E_MESSAGE_ALTERED.
  249. https://github.com/curl/curl/issues/5488
  250. 2.12 FTPS with Schannel times out file list operation
  251. "Instead of the command completing, it just sits there until the timeout
  252. expires." - the same command line seems to work with other TLS backends and
  253. other operating systems. See https://github.com/curl/curl/issues/5284.
  254. 2.14 Secure Transport disabling hostname validation also disables SNI
  255. SNI is the hostname that is sent by the TLS library to the server as part of
  256. the TLS handshake. Secure Transport does not send SNI when hostname validation
  257. is disabled. Servers that host multiple websites may not know which
  258. certificate to serve without SNI or which backend server to connect to. The
  259. server may serve the certificate of a default server or abort.
  260. If a server aborts a handshake then curl shows error "SSL peer handshake
  261. failed, the server most likely requires a client certificate to connect".
  262. In this case the error may also have been caused by lack of SNI.
  263. https://github.com/curl/curl/issues/6347
  264. 2.15 Renegotiate from server may cause hang for OpenSSL backend
  265. A race condition has been observed when, immediately after the initial
  266. handshake, curl has sent an HTTP request to the server and at the same time
  267. the server has sent a TLS hello request (renegotiate) to curl. Both are
  268. waiting for the other to respond. OpenSSL is supposed to send a handshake
  269. response but does not.
  270. https://github.com/curl/curl/issues/6785
  271. https://github.com/openssl/openssl/issues/14722
  272. 3. Email protocols
  273. 3.1 IMAP SEARCH ALL truncated response
  274. IMAP "SEARCH ALL" truncates output on large boxes. "A quick search of the
  275. code reveals that pingpong.c contains some truncation code, at line 408, when
  276. it deems the server response to be too large truncating it to 40 characters"
  277. https://curl.se/bug/view.cgi?id=1366
  278. 3.2 No disconnect command
  279. The disconnect commands (LOGOUT and QUIT) may not be sent by IMAP, POP3 and
  280. SMTP if a failure occurs during the authentication phase of a connection.
  281. 3.3 POP3 expects "CRLF.CRLF" eob for some single-line responses
  282. You have to tell libcurl not to expect a body, when dealing with one line
  283. response commands. Please see the POP3 examples and test cases which show
  284. this for the NOOP and DELE commands. https://curl.se/bug/?i=740
  285. 3.4 AUTH PLAIN for SMTP is not working on all servers
  286. Specifying "--login-options AUTH=PLAIN" on the command line does not seem to
  287. work correctly.
  288. See https://github.com/curl/curl/issues/4080
  289. 4. Command line
  290. 4.1 -J and -O with %-encoded file names
  291. -J/--remote-header-name does not decode %-encoded file names. RFC6266 details
  292. how it should be done. The can of worm is basically that we have no charset
  293. handling in curl and ascii >=128 is a challenge for us. Not to mention that
  294. decoding also means that we need to check for nastiness that is attempted,
  295. like "../" sequences and the like. Probably everything to the left of any
  296. embedded slashes should be cut off.
  297. https://curl.se/bug/view.cgi?id=1294
  298. -O also does not decode %-encoded names, and while it has even less
  299. information about the charset involved the process is similar to the -J case.
  300. Note that we will not add decoding to -O without the user asking for it with
  301. some other means as well, since -O has always been documented to use the name
  302. exactly as specified in the URL.
  303. 4.2 -J with -C - fails
  304. When using -J (with -O), automatically resumed downloading together with "-C
  305. -" fails. Without -J the same command line works. This happens because the
  306. resume logic is worked out before the target file name (and thus its
  307. pre-transfer size) has been figured out.
  308. https://curl.se/bug/view.cgi?id=1169
  309. 4.3 --retry and transfer timeouts
  310. If using --retry and the transfer timeouts (possibly due to using -m or
  311. -y/-Y) the next attempt does not resume the transfer properly from what was
  312. downloaded in the previous attempt but will truncate and restart at the
  313. original position where it was at before the previous failed attempt. See
  314. https://curl.se/mail/lib-2008-01/0080.html and Mandriva bug report
  315. https://qa.mandriva.com/show_bug.cgi?id=22565
  316. 5. Build and portability issues
  317. 5.1 OS400 port requires deprecated IBM library
  318. curl for OS400 requires QADRT to build, which provides ASCII wrappers for
  319. libc/POSIX functions in the ILE, but IBM no longer supports or even offers
  320. this library to download.
  321. See https://github.com/curl/curl/issues/5176
  322. 5.2 curl-config --libs contains private details
  323. "curl-config --libs" will include details set in LDFLAGS when configure is
  324. run that might be needed only for building libcurl. Further, curl-config
  325. --cflags suffers from the same effects with CFLAGS/CPPFLAGS.
  326. 5.3 curl compiled on OSX 10.13 failed to run on OSX 10.10
  327. See https://github.com/curl/curl/issues/2905
  328. 5.4 Build with statically built dependency
  329. The build scripts in curl (autotools, cmake and others) are primarily done to
  330. work with shared/dynamic third party dependencies. When linking with shared
  331. libraries, the dependency "chain" is handled automatically by the library
  332. loader - on all modern systems.
  333. If you instead link with a static library, we need to provide all the
  334. dependency libraries already at the link command line.
  335. Figuring out all the dependency libraries for a given library is hard, as it
  336. might also involve figuring out the dependencies of the dependencies and they
  337. may vary between platforms and even change between versions.
  338. When using static dependencies, the build scripts will mostly assume that
  339. you, the user, will provide all the necessary additional dependency libraries
  340. as additional arguments in the build. With configure, by setting LIBS/LDFLAGS
  341. on the command line.
  342. We welcome help to improve curl's ability to link with static libraries, but
  343. it is likely a task that we can never fully support.
  344. 5.5 cannot handle Unicode arguments in non-Unicode builds on Windows
  345. If a URL or filename cannot be encoded using the user's current codepage then
  346. it can only be encoded properly in the Unicode character set. Windows uses
  347. UTF-16 encoding for Unicode and stores it in wide characters, however curl
  348. and libcurl are not equipped for that at the moment except when built with
  349. _UNICODE and UNICODE defined. And, except for Cygwin, Windows cannot use UTF-8
  350. as a locale.
  351. https://curl.se/bug/?i=345
  352. https://curl.se/bug/?i=731
  353. https://curl.se/bug/?i=3747
  354. 5.6 make distclean loops forever
  355. Due to an issue (probably) in automake, "make distclean" can end up in a
  356. never-ending loop.
  357. See https://github.com/curl/curl/issues/7716
  358. 5.7 Visual Studio project gaps
  359. The Visual Studio projects lack some features that the autoconf and nmake
  360. builds offer, such as the following:
  361. - support for zlib and nghttp2
  362. - use of static runtime libraries
  363. - add the test suite components
  364. In addition to this the following could be implemented:
  365. - support for other development IDEs
  366. - add PATH environment variables for third-party DLLs
  367. 5.8 configure finding libs in wrong directory
  368. When the configure script checks for third-party libraries, it adds those
  369. directories to the LDFLAGS variable and then tries linking to see if it
  370. works. When successful, the found directory is kept in the LDFLAGS variable
  371. when the script continues to execute and do more tests and possibly check for
  372. more libraries.
  373. This can make subsequent checks for libraries wrongly detect another
  374. installation in a directory that was previously added to LDFLAGS by another
  375. library check.
  376. A possibly better way to do these checks would be to keep the pristine LDFLAGS
  377. even after successful checks and instead add those verified paths to a
  378. separate variable that only after all library checks have been performed gets
  379. appended to LDFLAGS.
  380. 5.9 Utilize Requires.private directives in libcurl.pc
  381. https://github.com/curl/curl/issues/864
  382. 5.10 curl hangs on SMB upload over stdin
  383. See https://github.com/curl/curl/issues/7896
  384. 5.11 configure --with-gssapi with Heimdal is ignored on macOS
  385. ... unless you also pass --with-gssapi-libs
  386. https://github.com/curl/curl/issues/3841
  387. 5.12 flaky Windows CI builds
  388. We run many CI builds for each commit and PR on github, and especially a
  389. number of the Windows builds are flaky. This means that we rarely get all CI
  390. builds go green and complete without errors. This is unfortunate as it makes
  391. us sometimes miss actual build problems and it is surprising to newcomers to
  392. the project who (rightfully) do not expect this.
  393. See https://github.com/curl/curl/issues/6972
  394. 6. Authentication
  395. 6.1 NTLM authentication and unicode
  396. NTLM authentication involving unicode user name or password only works
  397. properly if built with UNICODE defined together with the Schannel
  398. backend. The original problem was mentioned in:
  399. https://curl.se/mail/lib-2009-10/0024.html
  400. https://curl.se/bug/view.cgi?id=896
  401. The Schannel version verified to work as mentioned in
  402. https://curl.se/mail/lib-2012-07/0073.html
  403. 6.2 MIT Kerberos for Windows build
  404. libcurl fails to build with MIT Kerberos for Windows (KfW) due to KfW's
  405. library header files exporting symbols/macros that should be kept private to
  406. the KfW library. See ticket #5601 at https://krbdev.mit.edu/rt/
  407. 6.3 NTLM in system context uses wrong name
  408. NTLM authentication using SSPI (on Windows) when (lib)curl is running in
  409. "system context" will make it use wrong(?) user name - at least when compared
  410. to what winhttp does. See https://curl.se/bug/view.cgi?id=535
  411. 6.4 Negotiate and Kerberos V5 need a fake user name
  412. In order to get Negotiate (SPNEGO) authentication to work in HTTP or Kerberos
  413. V5 in the email protocols, you need to provide a (fake) user name (this
  414. concerns both curl and the lib) because the code wrongly only considers
  415. authentication if there's a user name provided by setting
  416. conn->bits.user_passwd in url.c https://curl.se/bug/view.cgi?id=440 How?
  417. https://curl.se/mail/lib-2004-08/0182.html A possible solution is to
  418. either modify this variable to be set or introduce a variable such as
  419. new conn->bits.want_authentication which is set when any of the authentication
  420. options are set.
  421. 6.5 NTLM does not support password with § character
  422. https://github.com/curl/curl/issues/2120
  423. 6.6 libcurl can fail to try alternatives with --proxy-any
  424. When connecting via a proxy using --proxy-any, a failure to establish an
  425. authentication will cause libcurl to abort trying other options if the
  426. failed method has a higher preference than the alternatives. As an example,
  427. --proxy-any against a proxy which advertise Negotiate and NTLM, but which
  428. fails to set up Kerberos authentication will not proceed to try authentication
  429. using NTLM.
  430. https://github.com/curl/curl/issues/876
  431. 6.7 Do not clear digest for single realm
  432. https://github.com/curl/curl/issues/3267
  433. 6.8 RTSP authentication breaks without redirect support
  434. RTSP authentication broke in 7.66.0. A work-around is to enable RTSP in
  435. CURLOPT_REDIR_PROTOCOLS. Authentication should however not be considered an
  436. actual redirect so a "proper" fix needs to be different and not require users
  437. to allow redirects to RTSP to work.
  438. See https://github.com/curl/curl/pull/4750
  439. 6.9 SHA-256 digest not supported in Windows SSPI builds
  440. Windows builds of curl that have SSPI enabled use the native Windows API calls
  441. to create authentication strings. The call to InitializeSecurityContext fails
  442. with SEC_E_QOP_NOT_SUPPORTED which causes curl to fail with CURLE_AUTH_ERROR.
  443. Microsoft does not document supported digest algorithms and that SEC_E error
  444. code is not a documented error for InitializeSecurityContext (digest).
  445. https://github.com/curl/curl/issues/6302
  446. 6.10 curl never completes Negotiate over HTTP
  447. Apparently it is not working correctly...?
  448. See https://github.com/curl/curl/issues/5235
  449. 6.11 Negotiate on Windows fails
  450. When using --negotiate (or NTLM) with curl on Windows, SSL/TSL handshake
  451. fails despite having a valid kerberos ticket cached. Works without any issue
  452. in Unix/Linux.
  453. https://github.com/curl/curl/issues/5881
  454. 6.12 cannot use Secure Transport with Crypto Token Kit
  455. https://github.com/curl/curl/issues/7048
  456. 7. FTP
  457. 7.1 FTP without or slow 220 response
  458. If a connection is made to an FTP server but the server then just never sends
  459. the 220 response or otherwise is dead slow, libcurl will not acknowledge the
  460. connection timeout during that phase but only the "real" timeout - which may
  461. surprise users as it is probably considered to be the connect phase to most
  462. people. Brought up (and is being misunderstood) in:
  463. https://curl.se/bug/view.cgi?id=856
  464. 7.2 FTP with CONNECT and slow server
  465. When doing FTP over a socks proxy or CONNECT through HTTP proxy and the multi
  466. interface is used, libcurl will fail if the (passive) TCP connection for the
  467. data transfer is not more or less instant as the code does not properly wait
  468. for the connect to be confirmed. See test case 564 for a first shot at a test
  469. case.
  470. 7.3 FTP with NOBODY and FAILONERROR
  471. It seems sensible to be able to use CURLOPT_NOBODY and CURLOPT_FAILONERROR
  472. with FTP to detect if a file exists or not, but it is not working:
  473. https://curl.se/mail/lib-2008-07/0295.html
  474. 7.4 FTP with ACCT
  475. When doing an operation over FTP that requires the ACCT command (but not when
  476. logging in), the operation will fail since libcurl does not detect this and
  477. thus fails to issue the correct command:
  478. https://curl.se/bug/view.cgi?id=635
  479. 7.5 ASCII FTP
  480. FTP ASCII transfers do not follow RFC959. They do not convert the data
  481. accordingly (not for sending nor for receiving). RFC 959 section 3.1.1.1
  482. clearly describes how this should be done:
  483. The sender converts the data from an internal character representation to
  484. the standard 8-bit NVT-ASCII representation (see the Telnet
  485. specification). The receiver will convert the data from the standard
  486. form to his own internal form.
  487. Since 7.15.4 at least line endings are converted.
  488. 7.6 FTP with NULs in URL parts
  489. FTP URLs passed to curl may contain NUL (0x00) in the RFC 1738 <user>,
  490. <password>, and <fpath> components, encoded as "%00". The problem is that
  491. curl_unescape does not detect this, but instead returns a shortened C string.
  492. From a strict FTP protocol standpoint, NUL is a valid character within RFC
  493. 959 <string>, so the way to handle this correctly in curl would be to use a
  494. data structure other than a plain C string, one that can handle embedded NUL
  495. characters. From a practical standpoint, most FTP servers would not
  496. meaningfully support NUL characters within RFC 959 <string>, anyway (e.g.,
  497. Unix pathnames may not contain NUL).
  498. 7.7 FTP and empty path parts in the URL
  499. libcurl ignores empty path parts in FTP URLs, whereas RFC1738 states that
  500. such parts should be sent to the server as 'CWD ' (without an argument). The
  501. only exception to this rule, is that we knowingly break this if the empty
  502. part is first in the path, as then we use the double slashes to indicate that
  503. the user wants to reach the root dir (this exception SHALL remain even when
  504. this bug is fixed).
  505. 7.8 Premature transfer end but healthy control channel
  506. When 'multi_done' is called before the transfer has been completed the normal
  507. way, it is considered a "premature" transfer end. In this situation, libcurl
  508. closes the connection assuming it does not know the state of the connection so
  509. it cannot be reused for subsequent requests.
  510. With FTP however, this is not necessarily true but there are a bunch of
  511. situations (listed in the ftp_done code) where it *could* keep the connection
  512. alive even in this situation - but the current code does not. Fixing this would
  513. allow libcurl to reuse FTP connections better.
  514. 7.9 Passive transfer tries only one IP address
  515. When doing FTP operations through a proxy at localhost, the reported spotted
  516. that curl only tried to connect once to the proxy, while it had multiple
  517. addresses and a failed connect on one address should make it try the next.
  518. After switching to passive mode (EPSV), curl should try all IP addresses for
  519. "localhost". Currently it tries ::1, but it should also try 127.0.0.1.
  520. See https://github.com/curl/curl/issues/1508
  521. 7.10 FTPS needs session reuse
  522. When the control connection is reused for a subsequent transfer, some FTPS
  523. servers complain about "missing session reuse" for the data channel for the
  524. second transfer.
  525. https://github.com/curl/curl/issues/4654
  526. 7.11 FTPS upload data loss with TLS 1.3
  527. During FTPS upload curl does not attempt to read TLS handshake messages sent
  528. after the initial handshake. OpenSSL servers running TLS 1.3 may send such a
  529. message. When curl closes the upload connection if unread data has been
  530. received (such as a TLS handshake message) then the TCP protocol sends an
  531. RST to the server, which may cause the server to discard or truncate the
  532. upload if it has not read all sent data yet, and then return an error to curl
  533. on the control channel connection.
  534. Since 7.78.0 this is mostly fixed. curl will do a single read before closing
  535. TLS connections (which causes the TLS library to read handshake messages),
  536. however there is still possibility of an RST if more messages need to be read
  537. or a message arrives after the read but before close (network race condition).
  538. https://github.com/curl/curl/issues/6149
  539. 8. TELNET
  540. 8.1 TELNET and time limitations do not work
  541. When using telnet, the time limitation options do not work.
  542. https://curl.se/bug/view.cgi?id=846
  543. 8.2 Microsoft telnet server
  544. There seems to be a problem when connecting to the Microsoft telnet server.
  545. https://curl.se/bug/view.cgi?id=649
  546. 9. SFTP and SCP
  547. 9.1 SFTP does not do CURLOPT_POSTQUOTE correct
  548. When libcurl sends CURLOPT_POSTQUOTE commands when connected to a SFTP server
  549. using the multi interface, the commands are not being sent correctly and
  550. instead the connection is "cancelled" (the operation is considered done)
  551. prematurely. There is a half-baked (busy-looping) patch provided in the bug
  552. report but it cannot be accepted as-is. See
  553. https://curl.se/bug/view.cgi?id=748
  554. 9.2 wolfssh: publickey auth does not work
  555. When building curl to use the wolfSSH backend for SFTP, the publickey
  556. authentication does not work. This is simply functionality not written for curl
  557. yet, the necessary API for make this work is provided by wolfSSH.
  558. See https://github.com/curl/curl/issues/4820
  559. 9.3 Remote recursive folder creation with SFTP
  560. On this servers, the curl fails to create directories on the remote server
  561. even when the CURLOPT_FTP_CREATE_MISSING_DIRS option is set.
  562. See https://github.com/curl/curl/issues/5204
  563. 10. SOCKS
  564. 10.3 FTPS over SOCKS
  565. libcurl does not support FTPS over a SOCKS proxy.
  566. 10.4 active FTP over a SOCKS
  567. libcurl does not support active FTP over a SOCKS proxy
  568. 11. Internals
  569. 11.1 Curl leaks .onion hostnames in DNS
  570. Curl sends DNS requests for hostnames with a .onion TLD. This leaks
  571. information about what the user is attempting to access, and violates this
  572. requirement of RFC7686: https://datatracker.ietf.org/doc/html/rfc7686
  573. Issue: https://github.com/curl/curl/issues/543
  574. 11.2 error buffer not set if connection to multiple addresses fails
  575. If you ask libcurl to resolve a hostname like example.com to IPv6 addresses
  576. only. But you only have IPv4 connectivity. libcurl will correctly fail with
  577. CURLE_COULDNT_CONNECT. But the error buffer set by CURLOPT_ERRORBUFFER
  578. remains empty. Issue: https://github.com/curl/curl/issues/544
  579. 11.3 Disconnects do not do verbose
  580. Due to how libcurl keeps connections alive in the "connection pool" after use
  581. to potentially transcend the life-time of the initial easy handle that was
  582. used to drive the transfer over that connection, it uses a *separate* and
  583. internal easy handle when it shuts down the connection. That separate
  584. connection might not have the same settings as the original easy handle, and
  585. in particular it is often note-worthy that it does not have the same VERBOSE
  586. and debug callbacks setup so that an application will not get the protocol
  587. data for the disconnect phase of a transfer the same way it got all the other
  588. data.
  589. This is because the original easy handle might have already been freed at that
  590. point and the application might not at all be prepared that the callback
  591. would get called again long after the handle was freed.
  592. See for example https://github.com/curl/curl/issues/6995
  593. 11.4 HTTP test server 'connection-monitor' problems
  594. The 'connection-monitor' feature of the sws HTTP test server does not work
  595. properly if some tests are run in unexpected order. Like 1509 and then 1525.
  596. See https://github.com/curl/curl/issues/868
  597. 11.5 Connection information when using TCP Fast Open
  598. CURLINFO_LOCAL_PORT (and possibly a few other) fails when TCP Fast Open is
  599. enabled.
  600. See https://github.com/curl/curl/issues/1332 and
  601. https://github.com/curl/curl/issues/4296
  602. 11.7 signal-based resolver timeouts
  603. libcurl built without an asynchronous resolver library uses alarm() to time
  604. out DNS lookups. When a timeout occurs, this causes libcurl to jump from the
  605. signal handler back into the library with a sigsetjmp, which effectively
  606. causes libcurl to continue running within the signal handler. This is
  607. non-portable and could cause problems on some platforms. A discussion on the
  608. problem is available at https://curl.se/mail/lib-2008-09/0197.html
  609. Also, alarm() provides timeout resolution only to the nearest second. alarm
  610. ought to be replaced by setitimer on systems that support it.
  611. 11.8 DoH leaks memory after followlocation
  612. https://github.com/curl/curl/issues/4592
  613. 11.9 DoH does not inherit all transfer options
  614. Some options are not inherited because they are not relevant for the DoH SSL
  615. connections, or inheriting the option may result in unexpected behavior. For
  616. example the user's debug function callback is not inherited because it would
  617. be unexpected for internal handles (ie DoH handles) to be passed to that
  618. callback.
  619. If an option is not inherited then it is not possible to set it separately for
  620. DoH without a DoH-specific option. For example: CURLOPT_DOH_SSL_VERIFYHOST,
  621. CURLOPT_DOH_SSL_VERIFYPEER and CURLOPT_DOH_SSL_VERIFYSTATUS.
  622. See https://github.com/curl/curl/issues/6605
  623. 11.10 Blocking socket operations in non-blocking API
  624. The list of blocking socket operations is in TODO section "More non-blocking".
  625. 11.11 A shared connection cache is not thread-safe
  626. The share interface offers CURL_LOCK_DATA_CONNECT to have multiple easy
  627. handle share a connection cache, but due to how connections are used they are
  628. still not thread-safe when used shared.
  629. See https://github.com/curl/curl/issues/4915 and lib1541.c
  630. 11.12 'no_proxy' string-matches IPv6 numerical addresses
  631. This has the downside that "::1" for example does not match "::0:1" even
  632. though they are in fact the same address.
  633. See https://github.com/curl/curl/issues/5745
  634. 11.13 wakeup socket disconnect causes havoc
  635. waking an iPad breaks the wakeup socket pair, triggering a POLLIN event and
  636. resulting in SOCKERRNO being set to ENOTCONN.
  637. This condition, and other possible error conditions on the wakeup socket, are
  638. not handled, so the condition remains on the FD and curl_multi_poll will
  639. never block again.
  640. See https://github.com/curl/curl/issues/6132 and
  641. https://github.com/curl/curl/pull/6133
  642. 11.14 Multi perform hangs waiting for threaded resolver
  643. If a threaded resolver takes a long time to complete, libcurl can be blocked
  644. waiting for it for a longer time than expected - and longer than the set
  645. timeouts.
  646. See https://github.com/curl/curl/issues/2975 and
  647. https://github.com/curl/curl/issues/4852
  648. 11.15 CURLOPT_OPENSOCKETPAIRFUNCTION is missing
  649. When libcurl creates sockets with socketpair(), those are not "exposed" in
  650. CURLOPT_OPENSOCKETFUNCTION and therefore might surprise and be unknown to
  651. applications that expect and want all sockets known beforehand. One way to
  652. address this issue is to introduce a CURLOPT_OPENSOCKETPAIRFUNCTION callback.
  653. https://github.com/curl/curl/issues/5747
  654. 11.16 libcurl uses renames instead of locking for atomic operations
  655. For saving cookies, alt-svc and hsts files. This is bad when for example the
  656. file is stored in a directory where the application has no write permission
  657. but it has permission for the file.
  658. https://github.com/curl/curl/issues/6882
  659. https://github.com/curl/curl/pull/6884
  660. 12. LDAP
  661. 12.1 OpenLDAP hangs after returning results
  662. By configuration defaults, openldap automatically chase referrals on
  663. secondary socket descriptors. The OpenLDAP backend is asynchronous and thus
  664. should monitor all socket descriptors involved. Currently, these secondary
  665. descriptors are not monitored, causing openldap library to never receive
  666. data from them.
  667. As a temporary workaround, disable referrals chasing by configuration.
  668. The fix is not easy: proper automatic referrals chasing requires a
  669. synchronous bind callback and monitoring an arbitrary number of socket
  670. descriptors for a single easy handle (currently limited to 5).
  671. Generic LDAP is synchronous: OK.
  672. See https://github.com/curl/curl/issues/622 and
  673. https://curl.se/mail/lib-2016-01/0101.html
  674. 12.2 LDAP on Windows does authentication wrong?
  675. https://github.com/curl/curl/issues/3116
  676. 12.3 LDAP on Windows does not work
  677. A simple curl command line getting "ldap://ldap.forumsys.com" returns an
  678. error that says "no memory" !
  679. https://github.com/curl/curl/issues/4261
  680. 12.4 LDAPS with NSS is slow
  681. See https://github.com/curl/curl/issues/5874
  682. 13. TCP/IP
  683. 13.1 --interface for ipv6 binds to unusable IP address
  684. Since IPv6 provides a lot of addresses with different scope, binding to an
  685. IPv6 address needs to take the proper care so that it does not bind to a
  686. locally scoped address as that is bound to fail.
  687. https://github.com/curl/curl/issues/686
  688. 13.2 Trying local ports fails on Windows
  689. This makes '--local-port [range]' to not work since curl can't properly
  690. detect if a port is already in use, so it'll try the first port, use that and
  691. then subsequently fail anyway if that was actually in use.
  692. https://github.com/curl/curl/issues/8112
  693. 14. DICT
  694. 14.1 DICT responses show the underlying protocol
  695. When getting a DICT response, the protocol parts of DICT are not stripped off
  696. from the output.
  697. https://github.com/curl/curl/issues/1809
  698. 15. CMake
  699. 15.1 use correct SONAME
  700. The autotools build sets the SONAME properly according to VERSIONINFO in
  701. lib/Makefile.am and so should cmake to make comparable build.
  702. See https://github.com/curl/curl/pull/5935
  703. 15.2 support build with GnuTLS
  704. 15.3 unusable tool_hugehelp.c with MinGW
  705. see https://github.com/curl/curl/issues/3125
  706. 15.4 build docs/curl.1
  707. The cmake build does not create the docs/curl.1 file and therefore must rely on
  708. it being there already. This makes the --manual option not work and test
  709. cases like 1139 cannot function.
  710. 15.5 build on Linux links libcurl to libdl
  711. ... which it should not need to!
  712. See https://github.com/curl/curl/issues/6165
  713. 15.6 uses -lpthread instead of Threads::Threads
  714. See https://github.com/curl/curl/issues/6166
  715. 15.7 generated .pc file contains strange entries
  716. The Libs.private field of the generated .pc file contains -lgcc -lgcc_s -lc
  717. -lgcc -lgcc_s
  718. See https://github.com/curl/curl/issues/6167
  719. 15.8 libcurl.pc uses absolute library paths
  720. The libcurl.pc file generated by cmake contains things like Libs.private:
  721. /usr/lib64/libssl.so /usr/lib64/libcrypto.so /usr/lib64/libz.so. The
  722. autotools equivalent would say Libs.private: -lssl -lcrypto -lz
  723. See https://github.com/curl/curl/issues/6169
  724. 15.9 cert paths autodetected when cross-compiling
  725. The autotools build disables the ca_path/ca_bundle detection when
  726. cross-compiling. The cmake build keeps doing the detection.
  727. See https://github.com/curl/curl/issues/6178
  728. 15.10 libpsl is not supported
  729. See https://github.com/curl/curl/issues/6214
  730. 15.11 ExternalProject_Add does not set CURL_CA_PATH
  731. CURL_CA_BUNDLE and CURL_CA_PATH are not set properly when cmake's
  732. ExternalProject_Add is used to build curl as a dependency.
  733. See https://github.com/curl/curl/issues/6313
  734. 15.12 cannot enable LDAPS on Windows
  735. See https://github.com/curl/curl/issues/6284
  736. 15.13 CMake build with MIT Kerberos does not work
  737. Minimum CMake version was bumped in curl 7.71.0 (#5358) Since CMake 3.2
  738. try_compile started respecting the CMAKE_EXE_FLAGS. The code dealing with
  739. MIT Kerberos detection sets few variables to potentially weird mix of space,
  740. and ;-separated flags. It had to blow up at some point. All the CMake checks
  741. that involve compilation are doomed from that point, the configured tree
  742. cannot be built.
  743. https://github.com/curl/curl/issues/6904
  744. 16. Applications
  745. 17. HTTP/2
  746. 17.1 Excessive HTTP/2 packets with TCP_NODELAY
  747. Because of how curl sets TCP_NODELAY by default, HTTP/2 requests are issued
  748. using more separate TCP packets than it would otherwise need to use. This
  749. means spending more bytes than it has to. Just disabling TCP_NODELAY for
  750. HTTP/2 is also not the correct fix because that then makes the outgoing
  751. packets to get delayed.
  752. See https://github.com/curl/curl/issues/6363
  753. 17.2 HTTP/2 frames while in the connection pool kill reuse
  754. If the server sends HTTP/2 frames (like for example an HTTP/2 PING frame) to
  755. curl while the connection is held in curl's connection pool, the socket will
  756. be found readable when considered for reuse and that makes curl think it is
  757. dead and then it will be closed and a new connection gets created instead.
  758. This is *best* fixed by adding monitoring to connections while they are kept
  759. in the pool so that pings can be responded to appropriately.
  760. 17.3 ENHANCE_YOUR_CALM causes infinite retries
  761. Infinite retries with 2 parallel requests on one connection receiving GOAWAY
  762. with ENHANCE_YOUR_CALM error code.
  763. See https://github.com/curl/curl/issues/5119
  764. 17.4 Connection failures with parallel HTTP/2
  765. See https://github.com/curl/curl/issues/5611
  766. 17.5 HTTP/2 connections through HTTPS proxy frequently stall
  767. See https://github.com/curl/curl/issues/6936
  768. 18. HTTP/3
  769. 18.1 If the HTTP/3 server closes connection during upload curl hangs
  770. See https://github.com/curl/curl/issues/6606
  771. 18.2 Transfer closed with n bytes remaining to read
  772. HTTP/3 transfers with the Jetty HTTP/3 server seem to not work.
  773. https://github.com/curl/curl/issues/8523
  774. 18.4 timeout when reusing a http3 connection
  775. HTTP/3 with quiche seems to not work and always timeout a subsequent transfer
  776. that reuses an already established connection
  777. https://github.com/curl/curl/issues/8764
  778. 18.9 connection migration does not work
  779. https://github.com/curl/curl/issues/7695