NAME

       curl_global_trace - log configuration

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_global_trace(const char *config);

DESCRIPTION

       This  function  configures the logging behavior to make some parts of curl more verbose or
       silent than others.

       This function may be called during the initialization phase of a program. It does not have
       to  be.  It  can  be  called several times even, possibly overwriting settings of previous
       calls.

       Calling  this  function  after  transfers  have  been  started  is  undefined.   On   some
       platforms/architectures it might take effect, on others not.

       This  function  is  thread-safe  since  libcurl  8.3.0  if  curl_version_info(3)  has  the
       CURL_VERSION_THREADSAFE feature bit set (most platforms).

       If this is not thread-safe, you must not call this function when any other thread  in  the
       program  (i.e.  a  thread  sharing the same memory) is running. This does not just mean no
       other thread that is using libcurl. Because  curl_global_init(3)  may  call  functions  of
       other  libraries that are similarly thread unsafe, it could conflict with any other thread
       that uses these other libraries.

       If you are initializing libcurl from a Windows DLL  you  should  not  initialize  it  from
       DllMain or a static initializer because Windows holds the loader lock during that time and
       it could cause a deadlock.

       The config string is a list of comma-separated component names. Names are case-insensitive
       and unknown names are ignored. The special name "all" applies to all components. Names may
       be prefixed with '+' or '-' to enable or disable detailed logging for a component.

       The list of component names is not part of curl's  public  API.  Names  may  be  added  or
       disappear  in  future  versions  of  libcurl.  Since  unknown  names are silently ignored,
       outdated log configurations does not cause errors when upgrading libcurl. Given that, some
       names can be expected to be fairly stable and are listed below for easy reference.

       Note  that log configuration applies only to transfers where debug logging is enabled. See
       CURLOPT_VERBOSE(3) or CURLOPT_DEBUGFUNCTION(3) on how to control that.

TRACE COMPONENTS

       tcp    Tracing of TCP socket handling: connect, sends, receives.

       ssl    Tracing of SSL/TLS operations, whichever SSL backend is used in your build.

       ftp    Tracing of FTP operations when this protocol is enabled in your build.

       http/2 Details about HTTP/2 handling: frames, events, I/O, etc.

       http/3 Details about HTTP/3 handling: connect, frames, events, I/O etc.

       http-proxy
              Involved  when  transfers  are  tunneled  through  an  HTTP  proxy.  "h1-proxy"  or
              "h2-proxy"  are  also  involved,  depending on the HTTP version negotiated with the
              proxy.

              In order to find out all components involved in  a  transfer,  run  it  with  "all"
              configured.  You  can  then  see  all names involved in your libcurl version in the
              trace.

       doh    Tracing of DNS-over-HTTP operations to resolve hostnames.

       read   Traces reading of upload data from the application in  order  to  send  it  to  the
              server.

       smtp   Tracing of SMTP operations when this protocol is enabled in your build.

       write  Traces writing of download data, received from the server, to the application.

       ws     Tracing of WebSocket operations when this protocol is enabled in your build.

TRACE GROUPS

       Besides the specific component names there are the following group names defined:

       all

       network
              All components involved in bare network I/O, including the SSL layer.

              All components that your libcurl is built with.

       protocol
              All components involved in transfer protocols, such as 'ftp' and 'http/2'.

       proxy  All components involved in use of proxies.

PROTOCOLS

       This functionality affects all supported protocols

EXAMPLE

       int main(void)
       {
         /* log details of HTTP/2 and SSL handling */
         curl_global_trace("http/2,ssl");

         /* log all details, except SSL handling */
         curl_global_trace("all,-ssl");
       }

       Below  is  a  trace  sample  where "http/2" was configured. The trace output of an enabled
       component appears at the beginning in brackets.
       * [HTTP/2] [h2sid=1] cf_send(len=96) submit https://example.com/
       ...
       * [HTTP/2] [h2sid=1] FRAME[HEADERS]
       * [HTTP/2] [h2sid=1] 249 header bytes
       ...

AVAILABILITY

       Added in curl 8.3

RETURN VALUE

       If this function returns non-zero, something went wrong and the configuration may not have
       any effects or may only been applied partially.

SEE ALSO

       curl_global_init(3), libcurl(3)