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--- |
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c: Copyright (C) Daniel Stenberg, <[email protected]>, 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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## `doh` |
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Tracing of DNS-over-HTTP operations to resolve hostnames. |
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## `read` |
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Traces reading of upload data from the application in order to send it to the server. |
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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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