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CURLOPT_RESOLVE(3) curl_easy_setopt options CURLOPT_RESOLVE(3)
CURLOPT_RESOLVE - provide custom host name to IP address resolves
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_RESOLVE,
struct curl_slist *hosts);
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 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 single name resolve string should be written using the format
[+]HOST:PORT:ADDRESS[,ADDRESS]... where HOST is the name libcurl will
try 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 pre-populates the DNS cache with entries for
the host+port pair so redirects and everything that operations against
the HOST+PORT will instead use your provided ADDRESS.
The optional leading "+" signifies whether the new entry should time-
out or not. Entries added with "HOST:..." will never time-out whereas
entries added with "+HOST:..." will time-out just like ordinary DNS
If the DNS cache already has an entry for the given host+port pair,
then this entry will be removed and a new entry will be created. This
is because the old entry may have have different addresses or a
different time-out setting.
An ADDRESS provided by this option will only be use if not restricted
by the setting of CURLOPT_IPRESOLVE(3) to a different IP version.
Remove names from the DNS cache again, to stop providing these fake
resolves, by including a string in the linked list that uses the format
"-HOST:PORT". The host name must be prefixed with a dash, and the host
name and port number must exactly match what was already added
Support for providing the ADDRESS within [brackets] was added in
Support for providing multiple IP addresses per entry was added in
Support for adding non-permanent entries by using the "+" prefix was
added in 7.75.0.
struct curl_slist *host = NULL;
host = curl_slist_append(NULL, "example.com:80:127.0.0.1");
curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_RESOLVE, host);
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
/* always cleanup */
Added in 7.21.3. Removal support added in 7.42.0.
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION
libcurl 7.78.0 April 24, 2021 CURLOPT_RESOLVE(3)