diff options
Diffstat (limited to 'docs/libcurl/opts/CURLOPT_RESOLVER_START_FUNCTION.md')
-rw-r--r-- | docs/libcurl/opts/CURLOPT_RESOLVER_START_FUNCTION.md | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/docs/libcurl/opts/CURLOPT_RESOLVER_START_FUNCTION.md b/docs/libcurl/opts/CURLOPT_RESOLVER_START_FUNCTION.md new file mode 100644 index 000000000..a9b490726 --- /dev/null +++ b/docs/libcurl/opts/CURLOPT_RESOLVER_START_FUNCTION.md @@ -0,0 +1,88 @@ +--- +c: Copyright (C) Daniel Stenberg, <daniel.se>, et al. +SPDX-License-Identifier: curl +Title: CURLOPT_RESOLVER_START_FUNCTION +Section: 3 +Source: libcurl +See-also: + - CURLOPT_PREREQFUNCTION (3) + - CURLOPT_RESOLVER_START_DATA (3) +--- + +# NAME + +CURLOPT_RESOLVER_START_FUNCTION - callback called before a new name resolve is started + +# SYNOPSIS + +~~~c +#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 prototype +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 is used, for example setting up +socket callback options. + +*reserved* is reserved. + +*userdata* is the user pointer set with the +CURLOPT_RESOLVER_START_DATA(3) option. + +The callback must return 0 on success. Returning a non-zero value causes the +resolve to fail. + +# DEFAULT + +NULL (No callback) + +# PROTOCOLS + +All + +# EXAMPLE + +~~~c +static int start_cb(void *resolver_state, void *reserved, + void *userdata) +{ + (void)reserved; + printf("Received resolver_state=%p userdata=%p\n", + resolver_state, userdata); + return 0; +} + +int main(void) +{ + CURL *curl = curl_easy_init(); + if(curl) { + curl_easy_setopt(curl, CURLOPT_RESOLVER_START_FUNCTION, 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 |