Commit Graph

1139 Commits

Author SHA1 Message Date
Daniel Stenberg
8ded8e5f3f
urldata: remove 'hostname' from struct Curl_async
It is unnecessary duplicated information, as the host name being
resolved is already present in conn->host.

Closes #16451
2025-02-27 17:18:43 +01:00
Daniel Stenberg
ac4a65f8d2
urldata: move the ech struct field to the "right place"
We keep the struct field ordered in a rough size order, big to small.

Closes #16489
2025-02-26 08:18:35 +01:00
Stefan Eissing
cfc657a48d
multi: event based rework
Rework the event based handling of transfers and connections to
be "localized" into a single source file with clearer dependencies.

- add multi_ev.c and multi_ev.h
- add docs/internal/MULTI-EV.md to explain the overall workings
- only do event handling book keeping when the socket callback
  is set
- add handling for "connection only" event tracking, when internal
  easy handles are used that are not really tied to a connection.
  Used in connection pool.
- remove transfer member "last_poll" and connections "shutdown_poll"
  and keep all that internal to multi_ev.c
- add CURL_TRC_M() for tracing of "multi" related things, including
  event handling and connection pool operations. Add new trace
  feature "multi" for trace config.
  multi traces will show exactly what is going on in regard to
  event handling.
- multi: trace transfers "mstate" in every CURL_TRC_M() call
- make internal trace buffer 2048 bytes and end the silliness
  with +n here -m there. Adjust test 1652 expectations of resulting
  length and input edge cases.
- add trace feature "lib-ids" to perfix libcurl traces with transfer
  and connection ids. Useful for debugging libcurl applications.

Closes #16308
2025-02-22 14:47:40 +01:00
Stefan Eissing
df5db8afaf
conn: fix connection reuse when SSL is optional
In curl 8.12 I tried to improve the logic on how we handle connections
that "upgrade" to TLS later, e.g. with a STARTTLS. I found the existing
code hard to read in this regard. But of course, the "improvements" blew
up in my face.

We fixed issues with imap, opo3, smtp in 8.12.1, but ftp was no longer
reusing existing, upgraded control connections as before. This PR adds
checks in our pytest FTP tests that verify reuse is happening as
intended.

I rewrote the logic in url.c again, so that the new test checks now pass.

Reported-by: Zenju on github
Fixes #16384
Closes #16392
2025-02-20 16:23:35 +01:00
Stefan Eissing
db72b8d4d0
http: version negotiation
Translate the `data->set.httpwant` which is one of the consts from the
public API (CURL_HTTP_VERSION_*) into a major version mask plus
additional flags for internal handling.

`Curl_http_neg_init()` does the translation and flags setting in http.c,
using new internal consts CURL_HTTP_V1x, CURL_HTTP_V2x and CURL_HTTP_V3x
for the major versions. The flags are

- only_10: when the application explicity asked fro HTTP/1.0
- h2_upgrade: when the application asks for upgrading 1.1 to 2.
- h2_prior_knowledge: when directly talking h2 without ALPN
- accept_09: when a HTTP/0.9 response is acceptable.

The Alt-Svc and HTTPS RR redirections from one ALPN to another obey the
allowed major versions. If a transfer has only h3 enabled, Alt-Svc
redirection to h2 is ignored.

This is the current implementation. It can be debated if Alt-Svc should
be able to override the allowed major versions. Added test_12_06 to
verify the current restriction.

Closes #16100
2025-02-18 16:10:12 +01:00
Daniel Stenberg
1ee06e873c
asyn-thread: remove 'status' from struct Curl_async
While it gets stored, nothing needs nor uses it.

Closes #16347
2025-02-16 14:35:33 +01:00
Daniel Stenberg
d9fc64d3ab
asyn-thread: do not allocate thread_data separately
Put the full struct into Curl_async since it will be used for every name
resolve anyway.

Closes #16241
2025-02-13 15:35:40 +01:00
Daniel Stenberg
94c596bbc5
all: remove FIXME and TODO comments
We can always improve. These comments tend to linger and go misleading
or plain wrong over time.

Closes #16283
2025-02-10 14:44:06 +01:00
Stefan Eissing
242a1439e7
vtsl: eliminate 'data->state.ssl_scache'
Keeping the relevant 'ssl_scache' in 'data->state' leads to problems
when the owner of the cache is cleaned up and this reference is left
dangling.

Remove the ref entirely and always find the ssl_scache at the current
share or multi.

Folded in #16260 (test 3208) to verify this fixes the bug with a
dangling reference when an easy handle is used with easy_perform first
and in a multi_perform after.

Ref: #16236
Closes #16261
2025-02-08 13:28:27 +01:00
Daniel Stenberg
35b1c1585b
urldata: tweak the UserDefined struct
By better sticking to listing the struct members sorted by size, this
struct is now 48 bytes smaller on my fairly maximized build, without
removing anything.

Turned 'connect_only' into two bits instead of an unsigned char with two
magic values.

Also put the 'gssapi_delegation' field within ifdef HAVE_GSSAPI.

Closes #16097
2025-01-27 15:47:18 +01:00
Stefan Eissing
1213c31272
lib: redirect handling by protocol handler
Adds a `follow()` callback to protocol handlers, so they may decide how
to act on a `newurl` after a request has been done. This is optional.

This moves the HTTP code for handling redirects from multi.c to http.c
where it should be. If we ever add a protocol with its own logic, it
would install its own follow function.

Closes #16075
2025-01-24 11:00:34 +01:00
Stefan Eissing
e83818cae1
lib: clarify 'conn->httpversion'
The variable `conn->httpversion` was used for several purposes and it
was unclear at which time the value represents what.

- rename `conn->httpversion` to `conn->httpversion_seen`
  This makes clear that the variable only records the last
  HTTP version seen on the connection - if any. And that it
  no longer is an indication of what version to use.
- Change Alt-Svc handling to no longer modify `conn->httpversion`
  but set `data->state.httpwant` for influencing the HTTP version
  to use on a transfer.
- Add `data->req.httpversion_sent` to have a record of what
  HTTP version was sent in a request
- Add connection filter type CF_TYPE_HTTP
- Add filter query `CF_QUERY_HTTP_VERSION` to ask what HTTP
  filter version is in place
- Lookup filters HTTP version instead of using `conn->httpversion`

Test test_12_05 now switches to HTTP/1.1 correctly and the
expectations have been fixed.

Removed the connection fitler "is_httpN()" checks and using
the version query instead.

Closes #16073
2025-01-24 10:59:02 +01:00
Stefan Eissing
34cebd8735
ssl session cache: change cache dimensions
Use a larger one when shared.

Closes #15953
2025-01-10 10:51:26 +01:00
Jakub Jelen
999cc818c5
openssl: add support to use keys and certificates from PKCS#11 provider
In OpenSSL < 3.0, the modularity was provided by mechanism called
"engines". This is supported in curl, but the engines got deprecated
with OpenSSL 3.0 in favor of more versatile providers.

This adds a support for OpenSSL Providers, to use PKCS#11 keys, namely
through the pkcs11 provider. This is done using similar approach as the
engines and this is automatically built in when the OpenSSL 3 and newer
is used.

Signed-off-by: Jakub Jelen <jjelen@redhat.com>

Closes #15587
2025-01-01 14:47:31 +01:00
Viktor Szakats
07a084f539
lib: remove __EMX__ guards
Follow-up to 179ee78e86 #2166
Closes #15884
2025-01-01 12:44:20 +01:00
Daniel Stenberg
9d5ecc9613
getinfo: provide info which auth was used for HTTP and proxy
CURLINFO_HTTPAUTH_USED and CURLINFO_PROXYAUTH_USED

Tested in 590 and 694

Ref: #12668
Idea-by: Ganesh Viswanathan
Closes #15450
2024-12-23 23:03:54 +01:00
Stefan Eissing
b06b35154f
getinfo: fix CURLINFO_QUEUE_TIME_T and add 'time_queue' var
Let CURLINFO_QUEUE_TIME_T count only the time a transfer spends queued,
including possible redirect requests.

Add var 'time_queue' for reporting the time in write outs.

Add test for verifying correct reporting.

Closes #15512
2024-12-21 12:04:48 +01:00
Daniel Stenberg
fc3e1cbc50
hyper: drop support
lib : remove all hyper code
configure: stop detecting hyper
docs: no more mention of hyper
tests: mo more special-handling of hyper builds
CI: no jobs using hyper

Closes #15120
2024-12-21 11:33:05 +01:00
Stefan Eissing
fa0ccd9f1f
lib: TLS session ticket caching reworked
Described in detail in internal doc TLS-SESSIONS.md

Main points:
- use a new `ssl_peer_key` for cache lookups by connection filters
- recognize differences between TLSv1.3 and other tickets
  * TLSv1.3 tickets are single-use, cache can hold several of them for a peer
  * TLSv1.2 are reused, keep only a single one per peer
- differentiate between ticket BLOB to store (that could be persisted) and object instances
- use put/take/return pattern for cache access
- remember TLS version, ALPN protocol, time received and lifetime of ticket
- auto-expire tickets after their lifetime

Closes #15774
2024-12-20 14:59:23 +01:00
Daniel Stenberg
9cc246401e
source: avoid use of 'very' in comments 2024-10-17 13:36:33 +02:00
Daniel Stenberg
9bee39bfed
url: use same credentials on redirect
Previously it could lose the username and only use the password.

Added test 998 and 999 to verify.

Reported-by: Tobias Bora
Fixes #15262
Closes #15282
2024-10-13 23:18:42 +02:00
Daniel Stenberg
3b43a05e00
netrc: cache the netrc file in memory
So that on redirects etc it does not reread the file but just parses it
again.

Reported-by: Pierre-Etienne Meunier
Fixes #15248
Closes #15259
2024-10-11 14:40:12 +02:00
Stefan Eissing
962097b8dd
TLS: TLSv1.3 earlydata support for curl
Based on #14135, implement TLSv1.3 earlydata support for the curl
command line, libcurl and its implementation in GnuTLS.

If a known TLS session announces early data support, and the feature is
enabled *and* it is not a "connect-only" transfer, delay the TLS
handshake until the first request is being sent.

- Add --tls-earldata as new boolean command line option for curl.
- Add CURLSSLOPT_EARLYDATA to libcurl to enable use of the feature.
- Add CURLINFO_EARLYDATA_SENT_T to libcurl, reporting the amount of
  bytes sent and accepted/rejected by the server.

Implementation details:
- store the ALPN protocol selected at the SSL session.
- When reusing the session and enabling earlydata, use exactly
  that ALPN protocol for negoptiation with the server. When the
  sessions ALPN does not match the connections ALPN, earlydata
  will not be enabled.
- Check that the server selected the correct ALPN protocol for
  an earlydata connect. If the server does not confirm or reports
  something different, the connect fails.
- HTTP/2: delay sending the initial SETTINGS frames during connect,
  if not connect-only.

Verification:
- add test_02_32 to verify earlydata GET with nghttpx.
- add test_07_70 to verify earlydata PUT with nghttpx.
- add support in 'hx-download', 'hx-upload' clients for the feature

Assisted-by: ad-chaos on github
Closes #15211
2024-10-11 12:28:22 +02:00
Daniel Stenberg
d78e129d50
WebSockets: make support official (non-experimental)
Inverts the configure/cmake options to instead provide options that
disable WebSockets and have them (ws + wss) enabled by default.

Closes #14936
2024-09-27 13:20:25 +02:00
Daniel Stenberg
7eda757d99
FTP: partly revert eeb7c12807
Since ASCII transfers on FTP means sending CRLF line endings, we should
still keep converting them to LF-only on platforms where text files
typically do not use CRLF.

This also DOES NOT convert existing CRLF line endings on ASCII uploads
but only does stand-alone LF => CRLF.

Regression from eeb7c12807 shipped in 8.10.0

Reported-by: finkjsc on github
Fixes #14873
Closes #14875
2024-09-14 17:23:04 +02:00
Stefan Eissing
435dd8aa6e
doh: cleanups
Mostly cleanup on identifiers of DoH code.
Always use 'Curl_doh_cleanup()' for releasing resources.

More concise and telling names (ymmv):

* prefix all static functions with 'doh_' for unity builds
* doh_encode -> doh_req_encode
* doh_decode -> doh_resp_decode
* struct dohdata -> struct doh_probes
* probe's 'serverdoh' -> 'resp_body'
* probe's 'dohbuffer' -> 'req_body'
* probe's 'headers' -> 'req_hds'
* 'dohprobe()' -> doh_run_probe()'
* 'DOH_PROBE_SLOTS' -> 'DOH_SLOT_COUNT'
* 'DOH_PROBE_SLOT_IPADDR_V4' -> 'DOH_SLOT_IPV4'
* 'DOH_PROBE_SLOT_IPADDR_V6' -> 'DOH_SLOT_IPV6'
* 'DOH_PROBE_SLOT_HTTPS' -> 'DOH_SLOT_HTTPS_RR'

Closes #14783
2024-09-06 08:58:52 +02:00
Stefan Eissing
00ef607326
url: fix connection reuse for HTTP/2 upgrades
Normally, when a connection's filters have all connected, the
multiplex status is determined. However, HTTP/2 Upgrade:
requests will only do this when the first server response
has been received.

The current connection reuse mechanism does not accomodate
that and when the time between connect and response is large
enough, connection reuse may not happen as desired.

See test case 2405 failures, such as in
https://github.com/curl/curl/actions/runs/10629497461/job/29467166451

Add 'conn->bits.asks_multiplex' as indicator that a connection is
still being evaluated for mulitplexing, so that new transfers
may wait on this to be cleared.

Closes #14739
2024-09-02 12:39:03 +02:00
Daniel Stenberg
eeb7c12807
ftp: always offer line end conversions
Previously this functionality was limited to platforms that not already
use CRLF as native line endings.

TODO: 4.5 ASCII support now considered fixed

Closes #14717
2024-08-29 20:24:37 +02:00
Stefan Eissing
64ab0ace27
urldata: remove crlf_conversions counter
Since the introduction of client writers, we check the body length in
the PROTOCOL phase and do FTP lineend conversions laster in the
CONTENT_DECODING phase. This means we no longer need to count the
conversions for length checks.

Closes #14709
2024-08-29 14:30:58 +02:00
Stefan Eissing
9280bbea3f
urldata: remove proxy_connect_closed bit
The connections 'proxy_connect_closed' bit was not used any more. Remove
it.

Closes #14708
2024-08-28 14:00:42 +02:00
Stefan Eissing
1be704e17e
cpool: rename "connection cache/conncache" to "Connection Pools/cpool"
This is a better match for what they do and the general "cpool"
var/function prefix works well.

The pool now handles very long hostnames correctly.

The following changes have been made:

* 'struct connectdata', e.g. connections, keep new members
  named `destination` and ' destination_len' that fully specifies
  interface+port+hostname of where the connection is going to.
  This is used in the pool for "bundling" of connections with
  the same destination. There is no limit on the length any more.
* Locking: all locks are done inside conncache.c when calling
  into the pool and released on return. This eliminates hazards
  of the callers keeping track.
* 'struct connectbundle' is now internal to the pool. It is no
  longer referenced by a connection.
* 'bundle->multiuse' no longer exists. HTTP/2 and 3 and TLS filters
  no longer need to set it. Instead, the multi checks on leaving
  MSTATE_CONNECT or MSTATE_CONNECTING if the connection is now
  multiplexed and new, e.g. not conn->bits.reuse. In that case
  the processing of pending handles is triggered.
* The pool's init is provided with a callback to invoke on all
  connections being discarded. This allows the cleanups in
  `Curl_disconnect` to run, wherever it is decided to retire
  a connection.
* Several pool operations can now be fully done with one call.
  Pruning dead connections, upkeep and checks on pool limits
  can now directly discard connections and need no longer return
  those to the caller for doing that (as we have now the callback
  described above).
* Finding a connection for reuse is now done via `Curl_cpool_find()`
  and the caller provides callbacks to evaluate the connection
  candidates.
* The 'Curl_cpool_check_limits()' now directly uses the max values
  that may be set in the transfer's multi. No need to pass them
  around. Curl_multi_max_host_connections() and
  Curl_multi_max_total_connections() are gone.
* Add method 'Curl_node_llist()' to get the llist a node is in.
  Used in cpool to verify connection are indeed in the list (or
  not in any list) as they need to.

I left the conncache.[ch] as is for now and also did not touch the
documentation. If we update that outside the feature window, we can
do this in a separate PR.

Multi-thread safety is not achieved by this PR, but since more details
on how pools operate are now "internal" it is a better starting
point to go for this in the future.

Closes #14662
2024-08-28 13:52:49 +02:00
Daniel Stenberg
3b057d4b7a
test1521: verify setting options to NULL better
Previously this test allowed several error values when setting options.
This made this test miss #14629.

Now, errors are generally not accepted for setopts:

 - numerical setopts accept CURLE_BAD_FUNCTION_ARGUMENT for funny input
 - the first setopt to an option accepts CURLE_NOT_BUILT_IN or
   CURLE_UNKNOWN_OPTION for when they are disabled/not built-in
 - there is an allowlist concept for some return code for some variables,
   managed at the top of the mk-lib1521.pl script

In curl.h: remove the OBSOLETE named values from the setopt list.

Closes #14634
2024-08-23 08:24:34 +02:00
Viktor Szakats
b042d5297d
tidy-up: misc spelling (bit, ASCII)
Closes #14559
2024-08-15 15:30:09 +02:00
Alex Snast
136504195a
getinfo: add CURLINFO_POSTTRANSFER_TIME_T
Returns the time, in microseconds, from the start until the last byte is
sent by libcurl (i.e. the request is sent off).

Closes #14189
2024-08-15 09:02:58 +02:00
Stefan Eissing
22d292b3ec
urldata: introduce data->mid, a unique identifier inside a multi
`data->id` is unique in *most* situations, but not in all. If a libcurl
application uses more than one connection cache, they will overlap. This
is a rare situations, but libcurl apps do crazy things. However, for
informative things, like tracing, `data->id` is superior, since it
assigns new ids in curl's serial curl_easy_perform() use.

Introduce `data->mid` which is a unique identifer inside one multi
instance, assigned on multi_add_handle() and cleared on
multi_remove_handle().

Use the `mid` in DoH operations and also in h2/h3 stream hashes.

Reported-by: 罗朝辉
Fixes #14414
Closes #14499
2024-08-14 11:21:34 +02:00
Max Faxälv
0a5ea09a91
spnego_gssapi: implement TLS channel bindings for openssl
Channel Bindings are used to tie the session context to a specific TLS
channel. This is to provide additional proof of valid identity,
mitigating authentication relay attacks.

Major web servers have the ability to require (None/Accept/Require)
GSSAPI channel binding, rendering Curl unable to connect to such
websites unless support for channel bindings is implemented.

IIS calls this feature Extended Protection (EPA), which is used in
Enterprise environments using Kerberos for authentication.

This change require krb5 >= 1.19, otherwise channel bindings won't be
forwarded through SPNEGO.

Co-Authored-By: Steffen Kieß <947515+steffen-kiess@users.noreply.github.com>
Closes #13098
2024-08-12 19:16:54 +02:00
Daniel Stenberg
ba235ab269
llist: remove direct struct accesses, use only functions
- Turned them all into functions to also do asserts etc.

- The llist related structs got all their fields renamed in order to make
  sure no existing code remains using direct access.

- Each list node struct now points back to the list it "lives in", so
  Curl_node_remove() no longer needs the list pointer.

- Rename the node struct and some of the access functions.

- Added lots of ASSERTs to verify API being used correctly

- Fix some cases of API misuse

Add docs/LLIST.md documenting the internal linked list API.

Closes #14485
2024-08-12 13:18:10 +02:00
Daniel Stenberg
f0a551814b
urldata: remove 'scratch' from the UrlState struct
It is not used anywhere anymore

Follow-up to e3905de819

Closes #14500
2024-08-12 12:55:20 +02:00
Daniel Stenberg
2c15ee4bdb
multi: make the "general" list of easy handles a Curl_llist
Instead of having an especially "unique" linked list handler for the
main list of easy handles within the multi handle, this now uses a
regular Curl_llist for this as well.

With this change, it is also clearer that every easy handle added to a
multi handle belongs to one and only one out of three different lists:

 process - the general one for normal transfer processing

 pending - queued up waiting to get a connection (MSTATE_PENDING)

 msgsent - transfer completed (MSTATE_MSGSENT)

An easy handle must therefore be removed from the current list before it
gets added to another.

Closes #14474
2024-08-10 23:24:58 +02:00
Viktor Szakats
f81f351b9a
tidy-up: OS names
Use these words and casing more consistently across text, comments and
one curl tool output:
AIX, ALPN, ANSI, BSD, Cygwin, Darwin, FreeBSD, GitHub, HP-UX, Linux,
macOS, MS-DOS, MSYS, MinGW, NTLM, POSIX, Solaris, UNIX, Unix, Unicode,
WINE, WebDAV, Win32, winbind, WinIDN, Windows, Windows CE, Winsock.

Mostly OS names and a few more.

Also a couple of other minor text fixups.

Closes #14360
2024-08-04 19:17:45 +02:00
Stefan Eissing
911c3166b6
lib: add eos flag to send methods
Adds a `bool eos` flag to send methods to indicate that the data
is the last chunk the invovled transfer wants to send to the server.

This will help protocol filters like HTTP/2 and 3 to forward the
stream's EOF flag and also allow to EAGAIN such calls when buffers
are not yet fully flushed.

Closes #14220
2024-08-03 19:53:54 +02:00
Stefan Eissing
0472afe5f9
vtls: init ssl peer only once
- check that `struct ssl_peer` is only initialized once
- fix vtls peer init to run only once
- check in peer init that hostname is not empty, fail otherwise

Closes #14152
2024-08-03 19:52:21 +02:00
Stefan Eissing
5a9262a333
url: dns_entry related improvements
Replace Curl_resolv_unlock() with Curl_resolv_unlink():

-replace inuse member with refcount in Curl_dns_entry

- pass Curl_dns_entry ** to unlink, so it gets always cleared

- solve potential (but unlikley) UAF in FTP's handling of looked up
  Curl_dns_entry. Esp. do not use addr information after unlinking an entry.
  In reality, the unlink will not free memory, as the dns entry is still
  referenced by the hostcache. But this is not safe and relying on no other
  code pruning the cache in the meantime.

- pass permanent flag when adding a dns entry instead of fixing timestamp
  afterwards.

url.c: fold several static *resolve_* functions into one.

Closes #14195
2024-08-03 19:51:02 +02:00
Stefan Eissing
ba44ac62e3
progress: ratelimit/progress tweaks
- multi.c: when ratelimiting a transfer stops (MSTATE_RATELIMITING ->
  MSTATE_PERFORMING), run the MSTATE_PERFORMING state right away

- urldata.h: factor out upload and download progress counters into a
  struct, use that for passing these to progress update functions

- progress.c/getinfo.c: change names of moved progress counters

- progress.c: use new structs and a helper struct to factor repeated
  calculation into static helpers

Closes #14335
2024-08-02 11:17:44 +02:00
Stefan Eissing
ae620a70a0
conncache: connection shutdown, multi_socket handling
- implement the socket hash user/reader/writer processing also
  for connections that are being shut down by the connection cache.
- split out handling of current vs. last pollset socket event handling
  into a function available in other code parts
- add `shutdown_poll` pollset to `connectdata` struct so that changes
  in the pollset can be recorded during shutdown. (The internal handle
  cannot keep it since it might be used for many connections)

Reported-by: calvin2021y on github
Fixes #14252
Closes #14257
2024-07-23 10:29:07 +02:00
Daniel Stenberg
25321de30e
Revert "lib: send eos flag"
This reverts commit be93299f10.
2024-07-19 01:38:05 +02:00
Stefan Eissing
be93299f10
lib: send eos flag
Adds a `bool eos` flag to send methods to indicate that the data is the
last chunk the invovled transfer wants to send to the server.

This will help protocol filters like HTTP/2 and 3 to forward the
stream's EOF flag and also allow to EAGAIN such calls when buffers are
not yet fully flushed.

Closes #14220
2024-07-18 23:27:35 +02:00
Stefan Eissing
46a26f122a
vtls: replace addsessionid with set_sessionid
- deduplicate the code in many tls backends that check
  for an existing id and delete it before adding the new one
- rename ssl_primary_config's `sessionid` bool to `cache_session`

Closes #14121
2024-07-09 23:14:58 +02:00
Daniel Stenberg
c074ba64a8
code: language cleanup in comments
Based on the standards and guidelines we use for our documentation.

 - expand contractions (they're => they are etc)
 - host name = > hostname
 - file name => filename
 - user name = username
 - man page => manpage
 - run-time => runtime
 - set-up => setup
 - back-end => backend
 - a HTTP => an HTTP
 - Two spaces after a period => one space after period

Closes #14073
2024-07-01 22:58:55 +02:00
Stefan Eissing
c9b95c0bb3
lib: graceful connection shutdown
When libcurl discards a connection there are two phases this may go
through: "shutdown" and "closing". If a connection is aborted, the
shutdown phase is skipped and it is closed right away.

The connection filters attached to the connection implement the phases
in their `do_shutdown()` and `do_close()` callbacks. Filters carry now a
`shutdown` flags next to `connected` to keep track of the shutdown
operation.

Filters are shut down from top to bottom. If a filter is not connected,
its shutdown is skipped. Notable filters that *do* something during
shutdown are HTTP/2 and TLS. HTTP/2 sends the GOAWAY frame. TLS sends
its close notify and expects to receive a close notify from the server.

As sends and receives may EAGAIN on the network, a shutdown is often not
successful right away and needs to poll the connection's socket(s). To
facilitate this, such connections are placed on a new shutdown list
inside the connection cache.

Since managing this list requires the cooperation of a multi handle,
only the connection cache belonging to a multi handle is used. If a
connection was in another cache when being discarded, it is removed
there and added to the multi's cache. If no multi handle is available at
that time, the connection is shutdown and closed in a one-time,
best-effort attempt.

When a multi handle is destroyed, all connection still on the shutdown
list are discarded with a final shutdown attempt and close. In curl
debug builds, the environment variable `CURL_GRACEFUL_SHUTDOWN` can be
set to make this graceful with a timeout in milliseconds given by the
variable.

The shutdown list is limited to the max number of connections configured
for a multi cache. Set via CURLMOPT_MAX_TOTAL_CONNECTIONS. When the
limit is reached, the oldest connection on the shutdown list is
discarded.

- In multi_wait() and multi_waitfds(), collect all connection caches
  involved (each transfer might carry its own) into a temporary list.
  Let each connection cache on the list contribute sockets and
  POLLIN/OUT events it's connections are waiting for.

- in multi_perform() collect the connection caches the same way and let
  them peform their maintenance. This will make another non-blocking
  attempt to shutdown all connections on its shutdown list.

- for event based multis (multi->socket_cb set), add the sockets and
  their poll events via the callback. When `multi_socket()` is invoked
  for a socket not known by an active transfer, forward this to the
  multi's cache for processing. On closing a connection, remove its
  socket(s) via the callback.

TLS connection filters MUST NOT send close nofity messages in their
`do_close()` implementation. The reason is that a TLS close notify
signals a success. When a connection is aborted and skips its shutdown
phase, the server needs to see a missing close notify to detect
something has gone wrong.

A graceful shutdown of FTP's data connection is performed implicitly
before regarding the upload/download as complete and continuing on the
control connection. For FTP without TLS, there is just the socket close
happening. But with TLS, the sent/received close notify signals that the
transfer is complete and healthy. Servers like `vsftpd` verify that and
reject uploads without a TLS close notify.

- added test_19_* for shutdown related tests
- test_19_01 and test_19_02 test for TCP RST packets
  which happen without a graceful shutdown and should
  no longer appear otherwise.
- add test_19_03 for handling shutdowns by the server
- add test_19_04 for handling shutdowns by curl
- add test_19_05 for event based shutdowny by server
- add test_30_06/07 and test_31_06/07 for shutdown checks
  on FTP up- and downloads.

Closes #13976
2024-06-26 08:33:17 +02:00