NAME

       CURLOPT_RESOLVE - provide custom hostname to IP address resolves

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_RESOLVE,
                                 struct curl_slist *hosts);

DESCRIPTION

       Pass  a  pointer  to a linked list of strings with hostname resolve information to use for
       requests with this handle. The linked  list  should  be  a  fully  valid  list  of  struct
       curl_slist  structs  properly  filled  in. Use curl_slist_append(3) to create the list and
       curl_slist_free_all(3) to clean up an entire list.

       Each resolve rule to add should be written using the format

        [+]HOST:PORT:ADDRESS[,ADDRESS]

       HOST is the name libcurl wants to resolve, PORT is the port number of  the  service  where
       libcurl wants to connect to the HOST and ADDRESS is one or more numerical IP addresses. If
       you specify multiple IP addresses they need to be separated by comma. If libcurl is  built
       to  support  IPv6,  each of the ADDRESS entries can of course be either IPv4 or IPv6 style
       addressing.

       Specify the host as a single ampersand (*) to match all names. This wildcard  is  resolved
       last so any resolve with a specific host and port number is given priority.

       This  option  effectively  populates  the DNS cache with entries for the host+port pair so
       redirects and everything that operations against the HOST+PORT instead use  your  provided
       ADDRESS.

       The  optional leading plus (+) specifies that the new entry should timeout.  Entries added
       without the leading plus character never times out whereas entries  added  with  +HOST:...
       times out just like ordinary DNS cache entries.

       If  the  DNS  cache  already  has  an  entry  for  the given host+port pair, the new entry
       overrides the former one.

       An ADDRESS provided by this option is only used  if  not  restricted  by  the  setting  of
       CURLOPT_IPRESOLVE(3) to a different IP version.

       To remove names from the DNS cache again, to stop providing these fake resolves, include a
       string in the linked list that uses the format

         -HOST:PORT

       The entry to remove must be prefixed with a dash, and the hostname and  port  number  must
       exactly match what was added previously.

DEFAULT

       NULL

PROTOCOLS

       This functionality affects all supported protocols

EXAMPLE

       int main(void)
       {
         CURL *curl;
         struct curl_slist *host = NULL;
         host = curl_slist_append(NULL, "example.com:443:127.0.0.1");

         curl = curl_easy_init();
         if(curl) {
           curl_easy_setopt(curl, CURLOPT_RESOLVE, host);
           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

           curl_easy_perform(curl);

           /* always cleanup */
           curl_easy_cleanup(curl);
         }

         curl_slist_free_all(host);
       }

HISTORY

       Added in 7.21.3. Removal support added in 7.42.0.

       Support for providing the ADDRESS within [brackets] was added in 7.57.0.

       Support for providing multiple IP addresses per entry was added in 7.59.0.

       Support for adding non-permanent entries by using the "+" prefix was added in 7.75.0.

AVAILABILITY

       Added in curl 7.21.3

RETURN VALUE

       Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.

SEE ALSO

       CURLOPT_CONNECT_TO(3), CURLOPT_DNS_CACHE_TIMEOUT(3), CURLOPT_IPRESOLVE(3)