ftp: fix socket leak on rare error

In the function AcceptServerConnect() the newly created socket would
leak if Curl_conn_tcp_accepted_set() returns error. Which basically
should nev

ftp: fix socket leak on rare error

In the function AcceptServerConnect() the newly created socket would
leak if Curl_conn_tcp_accepted_set() returns error. Which basically
should never happen.

Spotted by CodeSonar.

Closes #13417

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build: prefer `USE_IPV6` macro internally (was: `ENABLE_IPV6`)

Before this patch, two macros were used to guard IPv6 features in curl
sources: `ENABLE_IPV6` and `USE_IPV6`. This patch ma

build: prefer `USE_IPV6` macro internally (was: `ENABLE_IPV6`)

Before this patch, two macros were used to guard IPv6 features in curl
sources: `ENABLE_IPV6` and `USE_IPV6`. This patch makes the source use
the latter for consistency with other similar switches.

`-DENABLE_IPV6` remains accepted for compatibility as a synonym for
`-DUSE_IPV6`, when passed to the compiler.

`ENABLE_IPV6` also remains the name of the CMake and `Makefile.vc`
options to control this feature.

Closes #13349

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lib: add Curl_xfer_write_resp_hd

Add method in protocol handlers to allow writing of a single,
0-terminated header line. Avoids parsing and copying these lines.

Closes #13165

lib: keep conn IP information together

new struct ip_quadruple for holding local/remote addr+port

- used in data->info and conn and cf-socket.c
- copy back and forth complete st

lib: keep conn IP information together

new struct ip_quadruple for holding local/remote addr+port

- used in data->info and conn and cf-socket.c
- copy back and forth complete struct
- add 'secondary' to conn
- use secondary in reporting success for ftp 2nd connection

Reported-by: DasKutti on github
Fixes #13084
Closes #13090

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lib: client reader polish

- seek_func/seek_client, use transfer values only
- remove copies held in `struct connectdata`, use only
ever `data->set.seek_func`
- reso

lib: client reader polish

- seek_func/seek_client, use transfer values only
- remove copies held in `struct connectdata`, use only
ever `data->set.seek_func`
- resolves possible issues in multiuse connections
- new mime post reader eliminates need to ever overwriting this

- websockets, remove empty Curl_ws_done() function

Closes #13079

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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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ftp: Mark a const buffer as const

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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ftp: fix socket wait activity in ftp_domore_getsock

- when waiting on the data connection, always add the control socket to
the pollset on state STOP or let the pingpong add the socket

ftp: fix socket wait activity in ftp_domore_getsock

- when waiting on the data connection, always add the control socket to
the pollset on state STOP or let the pingpong add the socket according
to its needs.

Reported-by: Fabian Vogt
Fixes #12901
Closes #12913

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ftp: do lineend conversions in client writer

- remove the ftp special handling from sendf.c
- let ftp_do() add a client writer that does
the linened conversions
- change the li

ftp: do lineend conversions in client writer

- remove the ftp special handling from sendf.c
- let ftp_do() add a client writer that does
the linened conversions
- change the lineend conversion to no longer
modify the passed buffer, but write smaller
chunks to the next cwriter instead. The
inefficiency of this will be mitigated once
we add output buffering for all client writes.

Closes #12878

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ftp: treat a 226 arriving before data as a signal to read data

For active mode transfers.

Due to some interesting timing, curl can sometimes get the 226 (transfer
complete) over

ftp: treat a 226 arriving before data as a signal to read data

For active mode transfers.

Due to some interesting timing, curl can sometimes get the 226 (transfer
complete) over the control channel first, before the data connection
signals readability. If this happens, use that as a signal to check the
data connection.

Additionally, set the socket filter in listen mode *before* the
PORT/EPRT command is issued, to reduce the risk that the little time gap
could interfere.

This issue never reproduced for me on Debian and takes several hundred
rounds for me to trigger on my mac.

Reported-by: Stefan Eissing
Fixes #12823
Closes #12841

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file+ftp: use stack buffers instead of data->state.buffer

Closes #12789

pingpong: stop using the download buffer

The pingpong logic now uses its own dynbuf for receiving command
response data.

When the "final" response header for a commanad has been

pingpong: stop using the download buffer

The pingpong logic now uses its own dynbuf for receiving command
response data.

When the "final" response header for a commanad has been received, that
final line is left first in the recvbuf for the protocols to parse at
will. If there is additional data behind the final response line, the
'overflow' counter is indicate how many bytes.

Closes #12757

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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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ftp: only consider entry path if it has a length

Follow-up from 8edcfedc1a144f438bd1cdf814a0016cb

Bug: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=65631

Avoids a

ftp: only consider entry path if it has a length

Follow-up from 8edcfedc1a144f438bd1cdf814a0016cb

Bug: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=65631

Avoids a NULL pointer deref.

Closes #12648

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ftp: use memdup0 to store the OS from a SYST 215 response

avoid malloc + direct buffer fiddle

Closes #12639

ftp: use dynbuf to store entrypath

avoid direct malloc

Closes #12638

build: enable missing OpenSSF-recommended warnings, with fixes

https://best.openssf.org/Compiler-Hardening-Guides/Compiler-Options-Hardening-Guide-for-C-and-C++.html
as of 2023-11-29 [1]

build: enable missing OpenSSF-recommended warnings, with fixes

https://best.openssf.org/Compiler-Hardening-Guides/Compiler-Options-Hardening-Guide-for-C-and-C++.html
as of 2023-11-29 [1].

Enable new recommended warnings (except `-Wsign-conversion`):

- enable `-Wformat=2` for clang (in both cmake and autotools).
- add `CURL_PRINTF()` internal attribute and mark functions accepting
printf arguments with it. This is a copy of existing
`CURL_TEMP_PRINTF()` but using `__printf__` to make it compatible
with redefinting the `printf` symbol:
https://gcc.gnu.org/onlinedocs/gcc-3.0.4/gcc_5.html#SEC94
- fix `CURL_PRINTF()` and existing `CURL_TEMP_PRINTF()` for
mingw-w64 and enable it on this platform.
- enable `-Wimplicit-fallthrough`.
- enable `-Wtrampolines`.
- add `-Wsign-conversion` commented with a FIXME.
- cmake: enable `-pedantic-errors` the way we do it with autotools.
Follow-up to d5c0351055d5709da8f3e16c91348092fdb481aa #2747
- lib/curl_trc.h: use `CURL_FORMAT()`, this also fixes it to enable format
checks. Previously it was always disabled due to the internal `printf`
macro.

Fix them:

- fix bug where an `set_ipv6_v6only()` call was missed in builds with
`--disable-verbose` / `CURL_DISABLE_VERBOSE_STRINGS=ON`.
- add internal `FALLTHROUGH()` macro.
- replace obsolete fall-through comments with `FALLTHROUGH()`.
- fix fallthrough markups: Delete redundant ones (showing up as
warnings in most cases). Add missing ones. Fix indentation.
- silence `-Wformat-nonliteral` warnings with llvm/clang.
- fix one `-Wformat-nonliteral` warning.
- fix new `-Wformat` and `-Wformat-security` warnings.
- fix `CURL_FORMAT_SOCKET_T` value for mingw-w64. Also move its
definition to `lib/curl_setup.h` allowing use in `tests/server`.
- lib: fix two wrongly passed string arguments in log outputs.
Co-authored-by: Jay Satiro
- fix new `-Wformat` warnings on mingw-w64.

[1] https://github.com/ossf/wg-best-practices-os-developers/blob/56c0fde3895bfc55c8a973ef49a2572c507b2ae1/docs/Compiler-Hardening-Guides/Compiler-Options-Hardening-Guide-for-C-and-C%2B%2B.md

Closes #12489

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lib: rename Curl_strndup to Curl_memdup0 to avoid misunderstanding

Since the copy does not stop at a null byte, let's not call it anything
that makes you think it works like the common s

lib: rename Curl_strndup to Curl_memdup0 to avoid misunderstanding

Since the copy does not stop at a null byte, let's not call it anything
that makes you think it works like the common strndup() function.

Based on feedback from Jay Satiro, Stefan Eissing and Patrick Monnerat

Closes #12490

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lib: strndup/memdup instead of malloc, memcpy and null-terminate

- bufref: use strndup
- cookie: use strndup
- formdata: use strndup
- ftp: use strndup
- gtls: use aprin

lib: strndup/memdup instead of malloc, memcpy and null-terminate

- bufref: use strndup
- cookie: use strndup
- formdata: use strndup
- ftp: use strndup
- gtls: use aprintf instead of malloc + strcpy * 2
- http: use strndup
- mbedtls: use strndup
- md4: use memdup
- ntlm: use memdup
- ntlm_sspi: use strndup
- pingpong: use memdup
- rtsp: use strndup instead of malloc, memcpy and null-terminate
- sectransp: use strndup
- socks_gssapi.c: use memdup
- vtls: use dynbuf instead of malloc, snprintf and memcpy
- vtls: use strdup instead of malloc + memcpy
- wolfssh: use strndup

Closes #12453

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ftp: handle the PORT parsing without allocation

Also reduces amount of *cpy() calls.

Closes #12456

misc: fix -Walloc-size warnings

GCC 14 introduces a new -Walloc-size included in -Wextra which gives:

```
src/tool_operate.c: In function ‘add_per_transfer’:
src/tool_operat

misc: fix -Walloc-size warnings

GCC 14 introduces a new -Walloc-size included in -Wextra which gives:

```
src/tool_operate.c: In function ‘add_per_transfer’:
src/tool_operate.c:213:5: warning: allocation of insufficient size ‘1’ for type ‘struct per_transfer’ with size ‘480’ [-Walloc-size]
213 | p = calloc(sizeof(struct per_transfer), 1);
| ^
src/var.c: In function ‘addvariable’:
src/var.c:361:5: warning: allocation of insufficient size ‘1’ for type ‘struct var’ with size ‘32’ [-Walloc-size]
361 | p = calloc(sizeof(struct var), 1);
| ^
```

The calloc prototype is:
```
void *calloc(size_t nmemb, size_t size);
```

So, just swap the number of members and size arguments to match the
prototype, as we're initialising 1 struct of size `sizeof(struct
...)`. GCC then sees we're not doing anything wrong.

Closes #12292

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lib: introduce struct easy_poll_set for poll information

Connection filter had a `get_select_socks()` method, inspired by the
various `getsocks` functions involved during the lifetime of

lib: introduce struct easy_poll_set for poll information

Connection filter had a `get_select_socks()` method, inspired by the
various `getsocks` functions involved during the lifetime of a
transfer. These, depending on transfer state (CONNECT/DO/DONE/ etc.),
return sockets to monitor and flag if this shall be done for POLLIN
and/or POLLOUT.

Due to this design, sockets and flags could only be added, not
removed. This led to problems in filters like HTTP/2 where flow control
prohibits the sending of data until the peer increases the flow
window. The general transfer loop wants to write, adds POLLOUT, the
socket is writeable but no data can be written.

This leads to cpu busy loops. To prevent that, HTTP/2 did set the
`SEND_HOLD` flag of such a blocked transfer, so the transfer loop cedes
further attempts. This works if only one such filter is involved. If a
HTTP/2 transfer goes through a HTTP/2 proxy, two filters are
setting/clearing this flag and may step on each other's toes.

Connection filters `get_select_socks()` is replaced by
`adjust_pollset()`. They get passed a `struct easy_pollset` that keeps
up to `MAX_SOCKSPEREASYHANDLE` sockets and their `POLLIN|POLLOUT`
flags. This struct is initialized in `multi_getsock()` by calling the
various `getsocks()` implementations based on transfer state, as before.

After protocol handlers/transfer loop have set the sockets and flags
they want, the `easy_pollset` is *always* passed to the filters. Filters
"higher" in the chain are called first, starting at the first
not-yet-connection one. Each filter may add sockets and/or change
flags. When all flags are removed, the socket itself is removed from the
pollset.

Example:

* transfer wants to send, adds POLLOUT
* http/2 filter has a flow control block, removes POLLOUT and adds
POLLIN (it is waiting on a WINDOW_UPDATE from the server)
* TLS filter is connected and changes nothing
* h2-proxy filter also has a flow control block on its tunnel stream,
removes POLLOUT and adds POLLIN also.
* socket filter is connected and changes nothing
* The resulting pollset is then mixed together with all other transfers
and their pollsets, just as before.

Use of `SEND_HOLD` is no longer necessary in the filters.

All filters are adapted for the changed method. The handling in
`multi.c` has been adjusted, but its state handling the the protocol
handlers' `getsocks` method are untouched.

The most affected filters are http/2, ngtcp2, quiche and h2-proxy. TLS
filters needed to be adjusted for the connecting handshake read/write
handling.

No noticeable difference in performance was detected in local scorecard
runs.

Closes #11833

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spelling: fix codespell 2.2.6 typos

Closes #12019

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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