CURLOPT_RESOLVER_START_FUNCTION - callback called before a new name resolve is started
#include <curl/curl.h> int resolver_start_cb(void *resolver_state, void *reserved, void *userdata); CURLcode curl_easy_setopt(CURL *handle, CURLOPT_RESOLVER_START_FUNCTION, resolver_start_cb);
curl_easy_setopt options CURLOPT_RESOLVER_START_FUNCTION(3) NAME CURLOPT_RESOLVER_START_FUNCTION - callback called before a new name resolve is started SYNOPSIS #include <curl/curl.h> int resolver_start_cb(void *resolver_state, void *reserved, void *userdata); CURLcode curl_easy_setopt(CURL *handle, CURLOPT_RESOLVER_START_FUNCTION, resolver_start_cb); DESCRIPTION Pass a pointer to your callback function, which should match the proto- type shown above. This callback function gets called by libcurl every time before a new resolve request is started. resolver_state points to a backend-specific resolver state. Currently only the ares resolver backend has a resolver state. It can be used to set up any desired option on the ares channel before it's used, for example setting up socket callback options. reserved is reserved. userdata is the user pointer set with the CUR- LOPT_RESOLVER_START_DATA(3) option. The callback must return 0 on success. Returning a non-zero value will cause the resolve to fail. DEFAULT NULL (No callback) PROTOCOLS All EXAMPLE static int resolver_start_cb(void *resolver_state, void *reserved, void *userdata) { (void)reserved; printf("Received resolver_state=%p userdata=%p\n", resolver_state, userdata); return 0; } CURL *curl = curl_easy_init(); if(curl) { curl_easy_setopt(curl, CURLOPT_RESOLVER_START_FUNCTION, resolver_start_cb); curl_easy_setopt(curl, CURLOPT_RESOLVER_START_DATA, curl); curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); curl_easy_perform(curl); curl_easy_cleanup(curl); } AVAILABILITY Added in 7.59.0 RETURN VALUE Returns CURLE_OK ATTRIBUTES See attributes(7) for descriptions of the following attributes: +---------------+------------------+ |ATTRIBUTE TYPE | ATTRIBUTE VALUE | +---------------+------------------+ |Availability | web/curl | +---------------+------------------+ |Stability | Uncommitted | +---------------+------------------+ SEE ALSO CURLOPT_RESOLVER_START_DATA(3) NOTES Source code for open source software components in Oracle Solaris can be found at https://www.oracle.com/downloads/opensource/solaris-source- code-downloads.html. This software was built from source available at https://github.com/oracle/solaris-userland. The original community source was downloaded from https://curl.se/down- load/curl-7.83.1.tar.bz2. Further information about this software can be found on the open source community website at http://curl.haxx.se/. libcurl 7.83.1 September 08, 2021 CURLOPT_RESOLVER_START_FUNCTION(3)