transfer: do not use EXPIRE_NOW while blocked

- When a transfer sets `data->state.select_bits`, it is
scheduled for rerun with EXPIRE_NOW. If such a transfer
is blocked (due to P

transfer: do not use EXPIRE_NOW while blocked

- When a transfer sets `data->state.select_bits`, it is
scheduled for rerun with EXPIRE_NOW. If such a transfer
is blocked (due to PAUSE, for example), this will lead to
a busy loop.
- multi.c: check for transfer block
- sendf.*: add Curl_xfer_is_blocked()
- sendf.*: add client reader `is_paused()` callback
- implement is_paused()` callback where needed

Closes #13908

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sendf: fix two typos in comments

The parameters are named data, not date.

Closes #13393

cw-out: improved error handling

- remember error encountered in invoking write callback and always fail
afterwards without further invokes

- check behaviour in test_02_17 with

cw-out: improved error handling

- remember error encountered in invoking write callback and always fail
afterwards without further invokes

- check behaviour in test_02_17 with h2-pausing client

Reported-by: Pavel Kropachev
Fixes #13337
Closes #13340

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http: expect 100 rework

Move all handling of HTTP's `Expect: 100-continue` feature into a client
reader. Add sending flag `KEEP_SEND_TIMED` that triggers transfer
sending on general

http: expect 100 rework

Move all handling of HTTP's `Expect: 100-continue` feature into a client
reader. Add sending flag `KEEP_SEND_TIMED` that triggers transfer
sending on general events like a timer.

HTTP installs a `CURL_CR_PROTOCOL` reader when announcing `Expect:
100-continue`. That reader works as follows:

- on first invocation, records time, starts the `EXPIRE_100_TIMEOUT`
timer, disables `KEEP_SEND`, enables `KEEP_SEND_TIMER` and returns 0,
eos=FALSE like a paused upload.

- on subsequent invocation it checks if the timer has expired. If so, it
enables `KEEP_SEND` and switches to passing through reads to the
underlying readers.

Transfer handling's `readwrite()` will be invoked when a timer expires
(like `EXPIRE_100_TIMEOUT`) or when data from the server arrives. Seeing
`KEEP_SEND_TIMER`, it will try to upload more data, which triggers
reading from the client readers again. Which then may lead to a new
pausing or cause the upload to start.

Flags and timestamps connected to this have been moved from
`SingleRequest` into the reader's context.

Closes #13110

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hyper: implement unpausing via client reader

Just a tidy up to contain 'ifdef' pollution of common
code parts with implementation specifics.

- remove the ifdef hyper unpausing i

hyper: implement unpausing via client reader

Just a tidy up to contain 'ifdef' pollution of common
code parts with implementation specifics.

- remove the ifdef hyper unpausing in easy.c
- add hyper client reader for CURL_CR_PROTOCOL phase
that implements the unpause method for calling
the hyper waker if it is set

Closes #13075

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lib: add `void *ctx` to reader/writer instances

- `struct Curl_cwriter` and `struct Curl_creader` now carry a
`void *ctx` member that points to the instance as allocated.
- using `

lib: add `void *ctx` to reader/writer instances

- `struct Curl_cwriter` and `struct Curl_creader` now carry a
`void *ctx` member that points to the instance as allocated.
- using `r->ctx` and `w->ctx` as pointer to the instance specific
struct that has been allocated

Reported-by: Rudi Heitbaum
Fixes #13035
Closes #13059

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mime: add client reader

Add `mime` client reader. Encapsulates reading from mime parts, getting
their length, rewinding and unpausing.

- remove special mime handling from sendf.

mime: add client reader

Add `mime` client reader. Encapsulates reading from mime parts, getting
their length, rewinding and unpausing.

- remove special mime handling from sendf.c and easy.c
- add general "unpause" method to client readers
- use new reader in http/imap/smtp
- make some mime functions static that are now only used internally

In addition:
- remove flag 'forbidchunk' as no longer needed

Closes #13039

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lib: enhance client reader resume + rewind

- update client reader documentation
- client reader, add rewind capabilities
- tell creader to rewind on next start
- Curl_cli

lib: enhance client reader resume + rewind

- update client reader documentation
- client reader, add rewind capabilities
- tell creader to rewind on next start
- Curl_client_reset() will keep reader for future rewind if requested
- add Curl_client_cleanup() for freeing all resources independent of
rewinds
- add Curl_client_start() to trigger rewinds
- move rewind code from multi.c to sendf.c and make part of
"cr-in"'s implementation
- http, move the "resume_from" handling into the client readers
- the setup of a HTTP request is reshuffled to follow:
* determine method, target, auth negotiation
* install the client reader(s) for the request, including crlf
conversions and "chunked" encoding
* apply ranges to client reader
* concat request headers, upgrades, cookies, etc.
* complete request by determining Content-Length of installed
readers in combination with method
* send
- add methods for client readers to
* return the overall length they will generate (or -1 when unknown)
* return the amount of data on the CLIENT level, so that
expect-100 can decide if it want to apply itself
* set a "resume_from" offset or fail if unsupported
- struct HTTP has become largely empty now
- rename `Client_reader_*` to `Curl_creader_*`

Closes #13026

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lib: Curl_read/Curl_write clarifications

- replace `Curl_read()`, `Curl_write()` and `Curl_nwrite()` to
clarify when and at what level they operate
- send/recv of transfer related

lib: Curl_read/Curl_write clarifications

- replace `Curl_read()`, `Curl_write()` and `Curl_nwrite()` to
clarify when and at what level they operate
- send/recv of transfer related data is now done via
`Curl_xfer_send()/Curl_xfer_recv()` which no longer has
socket/socketindex as parameter. It decides on the transfer
setup of `conn->sockfd` and `conn->writesockfd` on which
connection filter chain to operate.
- send/recv on a specific connection filter chain is done via
`Curl_conn_send()/Curl_conn_recv()` which get the socket index
as parameter.
- rename `Curl_setup_transfer()` to `Curl_xfer_setup()` for
naming consistency
- clarify that the special CURLE_AGAIN hangling to return
`CURLE_OK` with length 0 only applies to `Curl_xfer_send()`
and CURLE_AGAIN is returned by all other send() variants.
- fix a bug in websocket `curl_ws_recv()` that mixed up data
when it arrived in more than a single chunk (to be made
into a sperate PR, also)

Added as documented [in
CLIENT-READER.md](https://github.com/curl/curl/blob/5b1f31dfbab8aef467c419c68aa06dc738cb75d4/docs/CLIENT-READERS.md).

- old `Curl_buffer_send()` completely replaced by new `Curl_req_send()`
- old `Curl_fillreadbuffer()` replaced with `Curl_client_read()`
- HTTP chunked uploads are now formatted in a client reader added when
needed.
- FTP line-end conversions are done in a client reader added when
needed.
- when sending requests headers, remaining buffer space is filled with
body data for sending in "one go". This is independent of the request
body size. Resolves #12938 as now small and large requests have the
same code path.

Changes done to test cases:

- test513: now fails before sending request headers as this initial
"client read" triggers the setup fault. Behaves now the same as in
hyper build
- test547, test555, test1620: fix the length check in the lib code to
only fail for reads *smaller* than expected. This was a bug in the
test code that never triggered in the old implementation.

Closes #12969

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lib: send rework

Curl_read/Curl_write clarifications

- replace `Curl_read()`, `Curl_write()` and `Curl_nwrite()` to 1clarify
when and at what level they operate

- sen

lib: send rework

Curl_read/Curl_write clarifications

- replace `Curl_read()`, `Curl_write()` and `Curl_nwrite()` to 1clarify
when and at what level they operate

- send/recv of transfer related data is now done via
`Curl_xfer_send()/Curl_xfer_recv()` which no longer has
socket/socketindex as parameter. It decides on the transfer setup of
`conn->sockfd` and `conn->writesockfd` on which connection filter
chain to operate.

- send/recv on a specific connection filter chain is done via
`Curl_conn_send()/Curl_conn_recv()` which get the socket index as
parameter.

- rename `Curl_setup_transfer()` to `Curl_xfer_setup()` for naming
consistency

- clarify that the special CURLE_AGAIN handling to return `CURLE_OK`
with length 0 only applies to `Curl_xfer_send()` and CURLE_AGAIN is
returned by all other send() variants.

SingleRequest reshuffling

- move functions into request.[ch]
- differentiate between reset and free
- add Curl_req_done() to perform last actions
- add a send `bufq` to SingleRequest for future use in keeping upload data

Closes #12963

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lib: move client writer into own source

Refactoring of the client writer that passes the data to the
client/application's callback functions.

- split out into own source cw-out.

lib: move client writer into own source

Refactoring of the client writer that passes the data to the
client/application's callback functions.

- split out into own source cw-out.[ch] from sendf.c

- move tempwrite and tempcount from data->state into the context of the
client writer

- redesign the 3 tempwrite dynbufs as a linked list of dynbufs. On
paused transfers, this allows to "record" interleaved HEADER/BODY
chunks to be "played back" in the same order on unpausing.

- keep the overall size limit of all buffered data to DYN_PAUSE_BUFFER.
On exceeding that, return CURLE_TOO_LARGE instead of
CURLE_OUT_OF_MEMORY as before.

- add method to be called when a transfer is DONE to allow writing of
any data still buffered

- when paused, record HEADER writes exactly as they come for later
playback. HEADERs are documented to be written one-by-one.

Closes #12898

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http: move headers collecting to writer

- add a client writer that does "push" response
headers written to the client if the headers api
is enabled
- remove special handling

http: move headers collecting to writer

- add a client writer that does "push" response
headers written to the client if the headers api
is enabled
- remove special handling in sendf.c
- needs to be installed very early on connection
setup to catch CONNECT response headers

Closes #12880

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sendf: Curl_client_write(), make passed in buf const

lib: replace readwrite with write_resp

This clarifies the handling of server responses by folding the code for
the complicated protocols into their protocol handlers. This concerns
m

lib: replace readwrite with write_resp

This clarifies the handling of server responses by folding the code for
the complicated protocols into their protocol handlers. This concerns
mainly HTTP and its bastard sibling RTSP.

The terms "read" and "write" are often used without clear context if
they refer to the connect or the client/application side of a
transfer. This PR uses "read/write" for operations on the client side
and "send/receive" for the connection, e.g. server side. If this is
considered useful, we can revisit renaming of further methods in another
PR.

Curl's protocol handler `readwrite()` method been changed:

```diff
- CURLcode (*readwrite)(struct Curl_easy *data, struct connectdata *conn,
- const char *buf, size_t blen,
- size_t *pconsumed, bool *readmore);
+ CURLcode (*write_resp)(struct Curl_easy *data, const char *buf, size_t blen,
+ bool is_eos, bool *done);
```

The name was changed to clarify that this writes reponse data to the
client side. The parameter changes are:

* `conn` removed as it always operates on `data->conn`
* `pconsumed` removed as the method needs to handle all data on success
* `readmore` removed as no longer necessary
* `is_eos` as indicator that this is the last call for the transfer
response (end-of-stream).
* `done` TRUE on return iff the transfer response is to be treated as
finished

This change affects many files only because of updated comments in
handlers that provide no implementation. The real change is that the
HTTP protocol handlers now provide an implementation.

The HTTP protocol handlers `write_resp()` implementation will get passed
**all** raw data of a server response for the transfer. The HTTP/1.x
formatted status and headers, as well as the undecoded response
body. `Curl_http_write_resp_hds()` is used internally to parse the
response headers and pass them on. This method is public as the RTSP
protocol handler also uses it.

HTTP/1.1 "chunked" transport encoding is now part of the general
*content encoding* writer stack, just like other encodings. A new flag
`CLIENTWRITE_EOS` was added for the last client write. This allows
writers to verify that they are in a valid end state. The chunked
decoder will check if it indeed has seen the last chunk.

The general response handling in `transfer.c:466` happens in function
`readwrite_data()`. This mainly operates now like:

```
static CURLcode readwrite_data(data, ...)
{
do {
Curl_xfer_recv_resp(data, buf)
...
Curl_xfer_write_resp(data, buf)
...
} while(interested);
...
}
```

All the response data handling is implemented in
`Curl_xfer_write_resp()`. It calls the protocol handler's `write_resp()`
implementation if available, or does the default behaviour.

All raw response data needs to pass through this function. Which also
means that anyone in possession of such data may call
`Curl_xfer_write_resp()`.

Closes #12480

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lib: client writer, part 2, accounting + logging

This PR has these changes:

Renaming of unencode_* to cwriter, e.g. client writers
- documentation of sendf.h functions
- mov

lib: client writer, part 2, accounting + logging

This PR has these changes:

Renaming of unencode_* to cwriter, e.g. client writers
- documentation of sendf.h functions
- move max decode stack checks back to content_encoding.c
- define writer phase which was used as order before
- introduce phases for monitoring inbetween decode phases
- offering default implementations for init/write/close

Add type paramter to client writer's do_write()
- always pass all writes through the writer stack
- writers who only care about BODY data will pass other writes unchanged

add RAW and PROTOCOL client writers
- RAW used for Curl_debug() logging of CURLINFO_DATA_IN
- PROTOCOL used for updates to data->req.bytecount, max_filesize checks and
Curl_pgrsSetDownloadCounter()
- remove all updates of data->req.bytecount and calls to
Curl_pgrsSetDownloadCounter() and Curl_debug() from other code
- adjust test457 expected output to no longer see the excess write

Closes #12184

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spelling: fix codespell 2.2.6 typos

Closes #12019

lib: move handling of `data->req.writer_stack` into Curl_client_write()

- move definitions from content_encoding.h to sendf.h
- move create/cleanup/add code into sendf.c
- installed

lib: move handling of `data->req.writer_stack` into Curl_client_write()

- move definitions from content_encoding.h to sendf.h
- move create/cleanup/add code into sendf.c
- installed content_encoding writers will always be called
on Curl_client_write(CLIENTWRITE_BODY)
- Curl_client_cleanup() frees writers and tempbuffers from
paused transfers, irregardless of protocol

Closes #11908

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lib: disambiguate Curl_client_write flag semantics

- use CLIENTWRITE_BODY *only* when data is actually body data
- add CLIENTWRITE_INFO for meta data that is *not* a HEADER
- debug a

lib: disambiguate Curl_client_write flag semantics

- use CLIENTWRITE_BODY *only* when data is actually body data
- add CLIENTWRITE_INFO for meta data that is *not* a HEADER
- debug assertions that BODY/INFO/HEADER is not used mixed
- move `data->set.include_header` check into Curl_client_write
so protocol handlers no longer have to care
- add special in FTP for `data->set.include_header` for historic,
backward compatible reasons
- move unpausing of client writes from easy.c to sendf.c, so that
code is in one place and can forward flags correctly

Closes #11885

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http: fix sending of large requests

- refs #11342 where errors with git https interactions
were observed
- problem was caused by 1st sends of size larger than 64KB
which resu

http: fix sending of large requests

- refs #11342 where errors with git https interactions
were observed
- problem was caused by 1st sends of size larger than 64KB
which resulted in later retries of 64KB only
- limit sending of 1st block to 64KB
- adjust h2/h3 filters to cope with parsing the HTTP/1.1
formatted request in chunks

- introducing Curl_nwrite() as companion to Curl_write()
for the many cases where the sockindex is already known

Fixes #11342 (again)
Closes #11803

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trace: make tracing available in non-debug builds

Add --trace-config to curl

Add curl_global_trace() to libcurl

Closes #11421

cf-socket: improvements in socket I/O handling

- Curl_write_plain/Curl_read_plain have been eliminated. Last code use
now uses Curl_conn_send/recv so that requests use conn->send/revc

cf-socket: improvements in socket I/O handling

- Curl_write_plain/Curl_read_plain have been eliminated. Last code use
now uses Curl_conn_send/recv so that requests use conn->send/revc
callbacks which defaults to cfilters use.
- Curl_recv_plain/Curl_send_plain have been internalized in cf-socket.c.
- USE_RECV_BEFORE_SEND_WORKAROUND (active on Windows) has been moved
into cf-socket.c. The pre_recv buffer is held at the socket filter
context. `postponed_data` structures have been removed from
`connectdata`.
- the hanger in HTTP/2 request handling was a result of read buffering
on all sends and the multi handling is not prepared for this. The
following happens:

- multi preforms on a HTTP/2 easy handle
- h2 reads and processes data
- this leads to a send of h2 data
- which receives and buffers before the send
- h2 returns
- multi selects on the socket, but no data arrives (its in the buffer already)
the workaround now receives data in a loop as long as there is something in
the buffer. The real fix would be for multi to change, so that `data_pending`
is evaluated before deciding to wait on the socket.

io_buffer, optional, in cf-socket.c, http/2 sets state.drain if lower
filter have pending data.

This io_buffer is only available/used when the
-DUSE_RECV_BEFORE_SEND_WORKAROUND is active, e.g. on Windows
configurations. It also maintains the original checks on protocol
handler being HTTP and conn->send/recv not being replaced.

The HTTP/2 (nghttp2) cfilter now sets data->state.drain when it finds
out that the "lower" filter chain has still pending data at the end of
its IO operation. This prevents the processing from becoming stalled.

Closes #10280

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curl_log: for failf/infof and debug logging implementations

- new functions and macros for cfilter debugging
- set CURL_DEBUG with names of cfilters where debug logging should be

curl_log: for failf/infof and debug logging implementations

- new functions and macros for cfilter debugging
- set CURL_DEBUG with names of cfilters where debug logging should be
enabled
- use GNUC __attribute__ to enable printf format checks during compile

Closes #10271

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copyright: update all copyright lines and remove year ranges

- they are mostly pointless in all major jurisdictions
- many big corporations and projects already don't use them
- save

copyright: update all copyright lines and remove year ranges

- they are mostly pointless in all major jurisdictions
- many big corporations and projects already don't use them
- saves us from pointless churn
- git keeps history for us
- the year range is kept in COPYING

checksrc is updated to allow non-year using copyright statements

Closes #10205

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sendf: change Curl_read_plain to wrap Curl_recv_plain (take 2)

Prior to this change Curl_read_plain would attempt to read the
socket directly. On Windows that's a problem because recv da

sendf: change Curl_read_plain to wrap Curl_recv_plain (take 2)

Prior to this change Curl_read_plain would attempt to read the
socket directly. On Windows that's a problem because recv data may be
cached by libcurl and that data is only drained using Curl_recv_plain.

Rather than rewrite Curl_read_plain to handle cached recv data, I
changed it to wrap Curl_recv_plain, in much the same way that
Curl_write_plain already wraps Curl_send_plain.

Curl_read_plain -> Curl_recv_plain
Curl_write_plain -> Curl_send_plain

This fixes a bug in the schannel backend where decryption of arbitrary
TLS records fails because cached recv data is never drained. We send
data (TLS records formed by Schannel) using Curl_write_plain, which
calls Curl_send_plain, and that may do a recv-before-send
("pre-receive") to cache received data. The code calls Curl_read_plain
to read data (TLS records from the server), which prior to this change
did not call Curl_recv_plain and therefore cached recv data wasn't
retrieved, resulting in malformed TLS records and decryption failure
(SEC_E_DECRYPT_FAILURE).

The bug has only been observed during Schannel TLS 1.3 handshakes. Refer
to the issue and PR for more information.

--

This is take 2 of the original fix. It preserves the original behavior
of Curl_read_plain to write 0 to the bytes read parameter on error,
since apparently some callers expect that (SOCKS tests were hanging).
The original fix which landed in 12e1def5 and was later reverted in
18383fbf failed to work properly because it did not do that.

Also, it changes Curl_write_plain the same way to complement
Curl_read_plain, and it changes Curl_send_plain to return -1 instead of
0 on CURLE_AGAIN to complement Curl_recv_plain.

Behavior on error with these changes:

Curl_recv_plain returns -1 and *code receives error code.
Curl_send_plain returns -1 and *code receives error code.
Curl_read_plain returns error code and *n (bytes read) receives 0.
Curl_write_plain returns error code and *written receives 0.

--

Ref: https://github.com/curl/curl/issues/9431#issuecomment-1312420361

Assisted-by: Joel Depooter
Reported-by: Egor Pugin

Fixes https://github.com/curl/curl/issues/9431
Closes https://github.com/curl/curl/pull/9949

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Revert "sendf: change Curl_read_plain to wrap Curl_recv_plain"

This reverts commit 12e1def51a75392df62e65490416007d7e68dab9.

It introduced SOCKS proxy fails, like test 700 never end

Revert "sendf: change Curl_read_plain to wrap Curl_recv_plain"

This reverts commit 12e1def51a75392df62e65490416007d7e68dab9.

It introduced SOCKS proxy fails, like test 700 never ending.

Reopens #9431

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