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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 resolve rule to add should be written using the format
... 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 "+" specifies that the new entry should time-out.
Entries added without the leading plus character will never time-out
whereas entries added with "+HOST:..." will time-out just like ordinary
DNS cache entries.
If the DNS cache already has an entry for the given host+port pair, the
new entry will override the former one.
An ADDRESS provided by this option will only be 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
The entry to remove must be prefixed with a dash, and the host name and
port number must exactly match what was added previously.
struct curl_slist *host = NULL;
host = curl_slist_append(NULL, "example.com:443:127.0.0.1");
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.
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.
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION
libcurl 7.86.0 September 20, 2022 CURLOPT_RESOLVE(3)