1--- 2c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. 3SPDX-License-Identifier: curl 4Title: curl_global_trace 5Section: 3 6Source: libcurl 7See-also: 8 - curl_global_init (3) 9 - libcurl (3) 10Protocol: 11 - All 12Added-in: 8.3 13--- 14 15# NAME 16 17curl_global_trace - log configuration 18 19# SYNOPSIS 20 21~~~c 22#include <curl/curl.h> 23 24CURLcode curl_global_trace(const char *config); 25~~~ 26 27# DESCRIPTION 28 29This function configures the logging behavior to make some parts of curl more 30verbose or silent than others. 31 32This function may be called during the initialization phase of a program. It 33does not have to be. It can be called several times even, possibly overwriting 34settings of previous calls. 35 36Calling this function after transfers have been started is undefined. On some 37platforms/architectures it might take effect, on others not. 38 39This function is thread-safe since libcurl 8.3.0 if curl_version_info(3) has 40the CURL_VERSION_THREADSAFE feature bit set (most platforms). 41 42If this is not thread-safe, you must not call this function when any other 43thread in the program (i.e. a thread sharing the same memory) is running. This 44does not just mean no other thread that is using libcurl. Because 45curl_global_init(3) may call functions of other libraries that are similarly 46thread unsafe, it could conflict with any other thread that uses these other 47libraries. 48 49If you are initializing libcurl from a Windows DLL you should not initialize 50it from *DllMain* or a static initializer because Windows holds the loader 51lock during that time and it could cause a deadlock. 52 53The *config* string is a list of comma-separated component names. Names are 54case-insensitive and unknown names are ignored. The special name "all" applies 55to all components. Names may be prefixed with '+' or '-' to enable or disable 56detailed logging for a component. 57 58The list of component names is not part of curl's public API. Names may be 59added or disappear in future versions of libcurl. Since unknown names are 60silently ignored, outdated log configurations does not cause errors when 61upgrading libcurl. Given that, some names can be expected to be fairly stable 62and are listed below for easy reference. 63 64Note that log configuration applies only to transfers where debug logging is 65enabled. See CURLOPT_VERBOSE(3) or CURLOPT_DEBUGFUNCTION(3) on how to control 66that. 67 68# TRACE COMPONENTS 69 70## `tcp` 71 72Tracing of TCP socket handling: connect, sends, receives. 73 74## `ssl` 75 76Tracing of SSL/TLS operations, whichever SSL backend is used in your build. 77 78## `ftp` 79 80Tracing of FTP operations when this protocol is enabled in your build. 81 82## `http/2` 83 84Details about HTTP/2 handling: frames, events, I/O, etc. 85 86## `http/3` 87 88Details about HTTP/3 handling: connect, frames, events, I/O etc. 89 90## `http-proxy` 91 92Involved when transfers are tunneled through an HTTP proxy. "h1-proxy" or 93"h2-proxy" are also involved, depending on the HTTP version negotiated with 94the proxy. 95 96In order to find out all components involved in a transfer, run it with "all" 97configured. You can then see all names involved in your libcurl version in the 98trace. 99 100## `doh` 101 102Tracing of DNS-over-HTTP operations to resolve hostnames. 103 104## `read` 105 106Traces reading of upload data from the application in order to send it to the server. 107 108## `smtp` 109 110Tracing of SMTP operations when this protocol is enabled in your build. 111 112## `write` 113 114Traces writing of download data, received from the server, to the application. 115 116## `ws` 117 118Tracing of WebSocket operations when this protocol is enabled in your build. 119 120# TRACE GROUPS 121 122Besides the specific component names there are the following group names 123defined: 124 125## `all` 126 127## `network` 128 129All components involved in bare network I/O, including the SSL layer. 130 131All components that your libcurl is built with. 132 133## `protocol` 134 135All components involved in transfer protocols, such as 'ftp' and 'http/2'. 136 137## `proxy` 138 139All components involved in use of proxies. 140 141# %PROTOCOLS% 142 143# EXAMPLE 144 145~~~c 146int main(void) 147{ 148 /* log details of HTTP/2 and SSL handling */ 149 curl_global_trace("http/2,ssl"); 150 151 /* log all details, except SSL handling */ 152 curl_global_trace("all,-ssl"); 153} 154~~~ 155 156Below is a trace sample where "http/2" was configured. The trace output 157of an enabled component appears at the beginning in brackets. 158~~~ 159* [HTTP/2] [h2sid=1] cf_send(len=96) submit https://example.com/ 160... 161* [HTTP/2] [h2sid=1] FRAME[HEADERS] 162* [HTTP/2] [h2sid=1] 249 header bytes 163... 164~~~ 165 166# %AVAILABILITY% 167 168# RETURN VALUE 169 170If this function returns non-zero, something went wrong and the configuration 171may not have any effects or may only been applied partially. 172
