tidy-up: spelling

C89, Schannel, Secure Transport, contractions.

Cherry-picked from #14692
Closes #14996

lib/src: white space edits to comply better with code style

... as checksrc now finds and complains about these.

Closes #14921

lib, src, tests: added space around ternary expressions

Closes #14912

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 n

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

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sectransp: fix setting tls version

Had multiple failures on test_17_09_ssl_min_max with --tlsv1 and
--tlsv1.3.

Closes #14621

vtls: fix static function name collisions between TLS backends

When using CMake Unity build.

- use unique name for `set_ssl_version_min_max()`
Fixes collision between GnuTLS,

vtls: fix static function name collisions between TLS backends

When using CMake Unity build.

- use unique name for `set_ssl_version_min_max()`
Fixes collision between GnuTLS, mbedTLS and SecureTransport.
```
lib\vtls\mbedtls.c(317,1): error C2084: function 'CURLcode set_ssl_version_min_max(Curl_easy *,ssl_peer *,ssl_primary_config *,const char **,const char *)' already has a body
lib\vtls\mbedtls.c(837,49): warning C4133: 'function': incompatible types - from 'Curl_cfilter *' to 'Curl_easy *'
lib\vtls\mbedtls.c(837,53): warning C4133: 'function': incompatible types - from 'Curl_easy *' to 'ssl_peer *'
lib\vtls\mbedtls.c(837,25): error C2198: 'set_ssl_version_min_max': too few arguments for call
```

- use unique name for `do_file_type()`
Fixes collision between GnuTLS, OpenSSL and wolfSSL.
```
lib\vtls\openssl.c(1053,12): error C2084: function 'gnutls_x509_crt_fmt_t do_file_type(const char *)' already has a body
```

Ref: https://github.com/curl/curl/actions/runs/10341162641/job/28622681573?pr=14484#step:10:31
Cherry-picked from #14495
Closes #14516

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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 ide

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

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vtls: add SSLSUPP_CIPHER_LIST

Added SSLSUPP_CIPHER_LIST so be able to differniate SSL Backends
that support CURLOPT_SSL_CIPHER_LIST.

Closes #14406

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,

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

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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

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

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Revert "lib: send eos flag"

This reverts commit be93299f10ef0b2bf7fe5c82140120073831867a.

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

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

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sectransp: fix clang compiler warnings, stop silencing them

Fix `-Wpointer-bool-conversion` warnings with the method suggested by
both Apple clang and mainline llvm. This was already tri

sectransp: fix clang compiler warnings, stop silencing them

Fix `-Wpointer-bool-conversion` warnings with the method suggested by
both Apple clang and mainline llvm. This was already tried and dropped
in #1705 (in year 2017), but the issue reported there no longer
replicates.

Verified with Apple clang 14, llvm 15, llvm 18 and gcc 11, 14 that the
generated objects are bit by bit identical before and after this patch.

Also:
- stop silencing `-Wtautological-pointer-compare`. This warning don't
seem to be appearing anymore (with or without this patch), at least
with the tested compilers and SDKs (clang 13.1.6-16.0.0beta, llvm 15,
18, gcc 11, 14) and minimum macOS target of 10.8. Older targets fail
to build curl with SecureTransport.

- silence `-Wunreachable-code` for clang only. Previously I applied it
also to GCC, by mistake.
Ref: https://github.com/curl/curl/pull/12331/commits/8d7172d20a48ebc6c1b1d94a76e2c5fb19dd9bfa

Apple clang `-Wpointer-bool-conversion`:
```
curl/lib/vtls/sectransp.c:1103:6: error: address of function 'SSLCreateContext' will always evaluate to 'true' [-Werror,-Wpointer-bool-conversion]
if(SSLCreateContext) { /* use the newer API if available */
~~ ^~~~~~~~~~~~~~~~
curl/lib/vtls/sectransp.c:1103:6: note: prefix with the address-of operator to silence this warning
if(SSLCreateContext) { /* use the newer API if available */
^
&
```
Ref: https://github.com/curl/curl/actions/runs/9819538439/job/27113201384#step:8:382

llvm `-Wpointer-bool-conversion`:
```
curl/lib/vtls/sectransp.c:2663:8: error: address of function 'SSLCreateContext' will always evaluate to 'true' [-Werror,-Wpointer-bool-conversion]
if(SSLCreateContext)
~~ ^~~~~~~~~~~~~~~~
curl/lib/vtls/sectransp.c:2663:8: note: prefix with the address-of operator to silence this warning
if(SSLCreateContext)
^
&
```
Ref: https://github.com/curl/curl/actions/runs/9819538439/job/27113200291#step:8:417

gcc still needs `-Waddress` suppressed to avoid these:
```
curl/lib/vtls/n/sectransp.c: In function 'getsubject':
curl/lib/vtls/n/sectransp.c:379:6: warning: the address of 'SecCertificateCopyLongDescription' will always evaluate as 'true' [-Waddress]
379 | if(&SecCertificateCopyLongDescription)
| ^
[...]
```

Follow-up to 59cadacfcc1d39472245979cdbd614c7a9af6f0d #14128
Follow-up to af271ce9b9717ba289417e9cbb7f278c2a12f959 #1722
Follow-up to 2b7ce3f56dfede107113c6de7d0ca457109d3eda #1706
Cherry-picked from #14097
Closes #14162

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build: sync warning options between autotools, cmake & compilers

- cmake: enable Apple-specific `-Werror=partial-availability` to match
autotools.

- autotools: enable `-pedant

build: sync warning options between autotools, cmake & compilers

- cmake: enable Apple-specific `-Werror=partial-availability` to match
autotools.

- autotools: enable `-pedantic-errors` with llvm/clang to match gcc and
CMake.

- autotools: enable `-Werror-implicit-function-declaration` for
llvm/clang to match gcc.

- cmake: enable `-Werror-implicit-function-declaration` to match
autotools.

- move `-Wpointer-bool-conversion` from autotools to the local file
(`sectransp.c`) it was meant to apply. This way it applies to all
build methods.

- autotoos: show `CURL_CFLAG_EXTRAS` in the `./configure` summary.
(it may contain `-Werror` and/or `-pedentic-errors`.)

Cherry-picked from #14097
Closes #14128

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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

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

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sectransp: fix `HAVE_BUILTIN_AVAILABLE` checks to not emit warnings

`HAVE_BUILTIN_AVAILABLE` is a curl macro set via autotools and cmake.
Like other `HAVE_`s it signals availability if d

sectransp: fix `HAVE_BUILTIN_AVAILABLE` checks to not emit warnings

`HAVE_BUILTIN_AVAILABLE` is a curl macro set via autotools and cmake.
Like other `HAVE_`s it signals availability if defined.

SecureTransport code was specifically looking for the value 1, which
triggered compiler warnings when the feature was not present.

Replace the existing workaround of locally suppressing the compiler
warning with using `defined()`.

autotools:
```
767 | #if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
| ^~~~~~~~~~~~~~~~~~~~~~
../../lib/vtls/sectransp.c: In function 'sectransp_connect_step1':
../../lib/vtls/sectransp.c:1140:52: error: "HAVE_BUILTIN_AVAILABLE" is not defined, evaluates to 0 [-Werror=undef]
1140 | #if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
| ^~~~~~~~~~~~~~~~~~~~~~
../../lib/vtls/sectransp.c:1240:52: error: "HAVE_BUILTIN_AVAILABLE" is not defined, evaluates to 0 [-Werror=undef]
1240 | #if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
| ^~~~~~~~~~~~~~~~~~~~~~
../../lib/vtls/sectransp.c: In function 'sectransp_connect_step2':
```
Ref: https://github.com/curl/curl/actions/runs/9815428701/job/27104448045#step:6:499

cmake gcc:
```
1140 | #if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
| ^~~~~~~~~~~~~~~~~~~~~~
/Users/runner/work/curl/curl/lib/vtls/sectransp.c:1240:52: error: "HAVE_BUILTIN_AVAILABLE" is not defined, evaluates to 0 [-Werror=undef]
1240 | #if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
| ^~~~~~~~~~~~~~~~~~~~~~
/Users/runner/work/curl/curl/lib/vtls/sectransp.c: In function 'sectransp_connect_step2':
/Users/runner/work/curl/curl/lib/vtls/sectransp.c:2231:51: error: "HAVE_BUILTIN_AVAILABLE" is not defined, evaluates to 0 [-Werror=undef]
2231 | #if(CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
| ^~~~~~~~~~~~~~~~~~~~~~
```
Ref: https://github.com/curl/curl/actions/runs/9815428701/job/27104445425#step:8:355

Cherry-picked from #14097
Closes #14122

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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

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

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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 phas

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

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connection: shutdown TLS (for FTP) better

This adds connection shutdown infrastructure and first use for FTP. FTP
data connections, when not encountering an error, are now shut down in a

connection: shutdown TLS (for FTP) better

This adds connection shutdown infrastructure and first use for FTP. FTP
data connections, when not encountering an error, are now shut down in a
blocking way with a 2sec timeout.

- add cfilter `Curl_cft_shutdown` callback
- keep a shutdown start timestamp and timeout at connectdata
- provide shutdown timeout default and member in
`data->set.shutdowntimeout`.
- provide methods for starting, interrogating and clearing
shutdown timers
- provide `Curl_conn_shutdown_blocking()` to shutdown the
`sockindex` filter chain in a blocking way. Use that in FTP.
- add `Curl_conn_cf_poll()` to wait for socket events during
shutdown of a connection filter chain.
This gets the monitoring sockets and events via the filters
"adjust_pollset()" methods. This gives correct behaviour when
shutting down a TLS connection through a HTTP/2 proxy.
- Implement shutdown for all socket filters
- for HTTP/2 and h2 proxying to send GOAWAY
- for TLS backends to the best of their capabilities
- for tcp socket filter to make a final, nonblocking
receive to avoid unwanted RST states
- add shutdown forwarding to happy eyeballers and
https connect ballers when applicable.

Closes #13904

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vtls: new io_need flags for poll handling

- decouple need to recv/send from negotiation state, we need
this later in shutdown handling as well
- move ssl enums from urldata.h to vt

vtls: new io_need flags for poll handling

- decouple need to recv/send from negotiation state, we need
this later in shutdown handling as well
- move ssl enums from urldata.h to vtls_int.h
- implement use of `connssl->io_need` in vtls.c. and all backends

Closes #13879

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lib/v*: tidy up types and casts

Also add a couple of negative checks.

Cherry-picked from #13489
Closes #13622

sectransp: remove large cipher table

Previously a large table of ciphers was used to determine the default
ciphers and to lookup manually selected ciphers names.

With the lookup

sectransp: remove large cipher table

Previously a large table of ciphers was used to determine the default
ciphers and to lookup manually selected ciphers names.

With the lookup of the manually selected cipher names moved to
Curl_cipher_suite_walk_str() the large table is no longer needed for
that purpose.

The list of manually selected cipher can now be intersected with the
ciphers supported by Secure Transport (SSLGetSupportedCiphers()),
instead of using the fixed table for that.

The other use of the table was to filter the list of all supported
ciphers offered by Secure Transport to create a list of ciphers to
use by default, excluding ciphers in the table marked as weak.

Instead of using a complement based approach (exclude weak), switch
to using an intersection with a smaller list of ciphers deemed
appropriate.

Closes #13823

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sectransp: use common code for cipher suite lookup

Take advantage of the Curl_cipher_suite_walk_str() and
Curl_cipher_suite_get_str() functions introduced in commit fba9afe.

Clo

sectransp: use common code for cipher suite lookup

Take advantage of the Curl_cipher_suite_walk_str() and
Curl_cipher_suite_get_str() functions introduced in commit fba9afe.

Closes #13521

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multi: add multi->proto_hash, a key-value store for protocol data

- add `Curl_hash_add2()` that passes a destructor function for
the element added. Call element destructor instead of h

multi: add multi->proto_hash, a key-value store for protocol data

- add `Curl_hash_add2()` that passes a destructor function for
the element added. Call element destructor instead of hash
destructor if present.
- multi: add `proto_hash` for protocol related information,
remove `struct multi_ssl_backend_data`.
- openssl: use multi->proto_hash to keep x509 shared store
- schannel: use multi->proto_hash to keep x509 shared store
- vtls: remove Curl_free_multi_ssl_backend_data() and its
equivalents in the TLS backends

Closes #13345

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vtls: TLS session storage overhaul

- add session with destructor callback
- remove vtls `session_free` method
- let `Curl_ssl_addsessionid()` take ownership
of session object,

vtls: TLS session storage overhaul

- add session with destructor callback
- remove vtls `session_free` method
- let `Curl_ssl_addsessionid()` take ownership
of session object, freeing it also on failures
- change tls backend use
- test_17, add tests for SSL session resumption

Closes #13386

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