.\" ************************************************************************** .\" * _ _ ____ _ .\" * Project ___| | | | _ \| | .\" * / __| | | | |_) | | .\" * | (__| |_| | _ <| |___ .\" * \___|\___/|_| \_\_____| .\" * .\" * Copyright (C) Daniel Stenberg, , et al. .\" * .\" * This software is licensed as described in the file COPYING, which .\" * you should have received as part of this distribution. The terms .\" * are also available at https://curl.se/docs/copyright.html. .\" * .\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell .\" * copies of the Software, and permit persons to whom the Software is .\" * furnished to do so, under the terms of the COPYING file. .\" * .\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY .\" * KIND, either express or implied. .\" * .\" * SPDX-License-Identifier: curl .\" * .\" ************************************************************************** .\" .TH CURLOPT_RESOLVE 3 "19 Jun 2014" libcurl libcurl .SH NAME CURLOPT_RESOLVE \- provide custom host name to IP address resolves .SH SYNOPSIS .nf #include CURLcode curl_easy_setopt(CURL *handle, CURLOPT_RESOLVE, struct curl_slist *hosts); .SH DESCRIPTION Pass a pointer to a linked list of strings with host name resolve information to use for requests with this handle. The linked list should be a fully valid list of \fBstruct curl_slist\fP structs properly filled in. Use \fIcurl_slist_append(3)\fP to create the list and \fIcurl_slist_free_all(3)\fP to clean up an entire list. Each resolve rule to add should be written using the format .nf [+]HOST:PORT:ADDRESS[,ADDRESS] .fi 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. 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 "+" specifies that the new entry should time-out. 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 \fICURLOPT_IPRESOLVE(3)\fP 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 .nf -HOST:PORT .fi The entry to remove must be prefixed with a dash, and the host name and port number must exactly match what was added previously. .SH DEFAULT NULL .SH PROTOCOLS All .SH EXAMPLE .nf 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); } .fi .SH AVAILABILITY 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. .SH RETURN VALUE Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. .SH "SEE ALSO" .BR CURLOPT_CONNECT_TO (3), .BR CURLOPT_DNS_CACHE_TIMEOUT (3), .BR CURLOPT_IPRESOLVE (3)