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Updated: Wednesday, July 27, 2022
 
 

CURLOPT_RESOLVE (3)

Name

CURLOPT_RESOLVE - provide custom host name to IP address resolves

Synopsis

#include <curl/curl.h>

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

Description

CURLOPT_RESOLVE(3)         curl_easy_setopt options         CURLOPT_RESOLVE(3)



NAME
       CURLOPT_RESOLVE - provide custom host name 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 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

        [+]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 mul-
       tiple 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

         -HOST:PORT

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

DEFAULT
       NULL

PROTOCOLS
       All

EXAMPLE
       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);

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.

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


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | web/curl         |
       +---------------+------------------+
       |Stability      | Uncommitted      |
       +---------------+------------------+

SEE ALSO
       CURLOPT_IPRESOLVE(3),     CURLOPT_DNS_CACHE_TIMEOUT(3),    CURLOPT_CON-
       NECT_TO(3),



NOTES
       Source code for open source software components in Oracle  Solaris  can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-
       code-downloads.html.

       This    software    was    built    from    source     available     at
       https://github.com/oracle/solaris-userland.    The  original  community
       source      was      downloaded       from        https://curl.se/down-
       load/curl-7.83.1.tar.bz2.

       Further information about this software can be found on the open source
       community website at http://curl.haxx.se/.



libcurl 7.83.1                 January 10, 2022             CURLOPT_RESOLVE(3)