cfc657a48d
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
201 lines
5.3 KiB
Markdown
201 lines
5.3 KiB
Markdown
---
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c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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SPDX-License-Identifier: curl
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Title: curl_global_trace
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Section: 3
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Source: libcurl
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See-also:
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- curl_global_init (3)
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- libcurl (3)
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Protocol:
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- All
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Added-in: 8.3
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---
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# NAME
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curl_global_trace - log configuration
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# SYNOPSIS
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~~~c
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#include <curl/curl.h>
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CURLcode curl_global_trace(const char *config);
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~~~
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# DESCRIPTION
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This function configures the logging behavior to make some parts of curl more
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verbose or silent than others.
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This function may be called during the initialization phase of a program. It
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does not have to be. It can be called several times even, possibly overwriting
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settings of previous calls.
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Calling this function after transfers have been started is undefined. On some
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platforms/architectures it might take effect, on others not.
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This function is thread-safe since libcurl 8.3.0 if curl_version_info(3) has
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the CURL_VERSION_THREADSAFE feature bit set (most platforms).
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If this is not thread-safe, you must not call this function when any other
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thread in the program (i.e. a thread sharing the same memory) is running. This
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does not just mean no other thread that is using libcurl. Because
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curl_global_init(3) may call functions of other libraries that are similarly
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thread unsafe, it could conflict with any other thread that uses these other
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libraries.
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If you are initializing libcurl from a Windows DLL you should not initialize
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it from *DllMain* or a static initializer because Windows holds the loader
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lock during that time and it could cause a deadlock.
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The *config* string is a list of comma-separated component names. Names are
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case-insensitive and unknown names are ignored. The special name "all" applies
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to all components. Names may be prefixed with '+' or '-' to enable or disable
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detailed logging for a component.
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The list of component names is not part of curl's public API. Names may be
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added or disappear in future versions of libcurl. Since unknown names are
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silently ignored, outdated log configurations does not cause errors when
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upgrading libcurl. Given that, some names can be expected to be fairly stable
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and are listed below for easy reference.
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Note that log configuration applies only to transfers where debug logging is
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enabled. See CURLOPT_VERBOSE(3) or CURLOPT_DEBUGFUNCTION(3) on how to control
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that.
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# TRACE COMPONENTS
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## `tcp`
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Tracing of TCP socket handling: connect, sends, receives.
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## `ssl`
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Tracing of SSL/TLS operations, whichever SSL backend is used in your build.
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## `ftp`
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Tracing of FTP operations when this protocol is enabled in your build.
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## `http/2`
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Details about HTTP/2 handling: frames, events, I/O, etc.
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## `http/3`
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Details about HTTP/3 handling: connect, frames, events, I/O etc.
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## `http-proxy`
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Involved when transfers are tunneled through an HTTP proxy. "h1-proxy" or
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"h2-proxy" are also involved, depending on the HTTP version negotiated with
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the proxy.
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In order to find out all components involved in a transfer, run it with "all"
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configured. You can then see all names involved in your libcurl version in the
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trace.
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## `dns`
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Tracing of DNS operations to resolve hostnames and HTTPS records.
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## `lib-ids`
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Adds transfer and connection identifiers as prefix to every call to
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CURLOPT_DEBUGFUNCTION(3). The format is `[n-m]` where `n` is the identifier
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of the transfer and `m` is the identifier of the connection. A literal `x`
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is used for internal transfers or when no connection is assigned.
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For example, `[5-x]` is the prefix for transfer 5 that has no
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connection. The command line tool `curl`uses the same format for its
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`--trace-ids` option.
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`lib-ids` is intended for libcurl applications that handle multiple
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transfers but have no own way to identify in trace output which transfer
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a trace event is connected to.
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## `doh`
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Former name for DNS-over-HTTP operations. Now an alias for `dns`.
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## `multi`
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Traces multi operations managing transfers' state changes and sockets poll
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states.
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## `read`
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Traces reading of upload data from the application in order to send it to the
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server.
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## `ssls`
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Tracing of SSL Session handling, e.g. caching/import/export.
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## `smtp`
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Tracing of SMTP operations when this protocol is enabled in your build.
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## `write`
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Traces writing of download data, received from the server, to the application.
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## `ws`
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Tracing of WebSocket operations when this protocol is enabled in your build.
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# TRACE GROUPS
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Besides the specific component names there are the following group names
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defined:
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## `all`
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## `network`
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All components involved in bare network I/O, including the SSL layer.
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All components that your libcurl is built with.
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## `protocol`
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All components involved in transfer protocols, such as 'ftp' and 'http/2'.
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## `proxy`
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All components involved in use of proxies.
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# %PROTOCOLS%
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# EXAMPLE
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~~~c
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int main(void)
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{
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/* log details of HTTP/2 and SSL handling */
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curl_global_trace("http/2,ssl");
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/* log all details, except SSL handling */
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curl_global_trace("all,-ssl");
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}
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~~~
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Below is a trace sample where "http/2" was configured. The trace output
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of an enabled component appears at the beginning in brackets.
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~~~
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* [HTTP/2] [h2sid=1] cf_send(len=96) submit https://example.com/
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...
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* [HTTP/2] [h2sid=1] FRAME[HEADERS]
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* [HTTP/2] [h2sid=1] 249 header bytes
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...
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~~~
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# %AVAILABILITY%
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# RETURN VALUE
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If this function returns non-zero, something went wrong and the configuration
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may not have any effects or may only been applied partially.
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