From a5f1e659d52872a499a5744870cb3e6ff382642f Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Tue, 25 Jul 2023 16:57:41 +0100
Subject: [PATCH] curl: Add ipresolve option

Allows you to force IPv4 or IPv6.

(cherry picked from commit d1b27c97f7fac00ee452a1d1b05805ee7145a49c)
---
 plugins/curl/curl.c                 | 15 +++++++++++++++
 plugins/curl/curldefs.h             |  1 +
 plugins/curl/nbdkit-curl-plugin.pod | 14 ++++++++++++++
 plugins/curl/pool.c                 |  2 ++
 4 files changed, 32 insertions(+)

diff --git a/plugins/curl/curl.c b/plugins/curl/curl.c
index 425f1d90..91fa65fb 100644
--- a/plugins/curl/curl.c
+++ b/plugins/curl/curl.c
@@ -68,6 +68,7 @@ struct curl_slist *headers = NULL;
 const char *header_script = NULL;
 unsigned header_script_renew = 0;
 long http_version = CURL_HTTP_VERSION_NONE;
+long ipresolve = CURL_IPRESOLVE_WHATEVER;
 char *password = NULL;
 #ifndef HAVE_CURLOPT_PROTOCOLS_STR
 long protocols = CURLPROTO_ALL;
@@ -314,6 +315,19 @@ curl_config (const char *key, const char *value)
     }
   }
 
+  else if (strcmp (key, "ipresolve") == 0) {
+    if (strcmp (value, "any") == 0 || strcmp (value, "whatever") == 0)
+      ipresolve = CURL_IPRESOLVE_WHATEVER;
+    else if (strcmp (value, "v4") == 0 || strcmp (value, "4") == 0)
+      ipresolve = CURL_IPRESOLVE_V4;
+    else if (strcmp (value, "v6") == 0 || strcmp (value, "6") == 0)
+      ipresolve = CURL_IPRESOLVE_V6;
+    else {
+      nbdkit_error ("unknown ipresolve: %s", value);
+      return -1;
+    }
+  }
+
   else if (strcmp (key, "password") == 0) {
     free (password);
     if (nbdkit_read_password (value, &password) == -1)
@@ -495,6 +509,7 @@ curl_config_complete (void)
   "header-script=<SCRIPT>     Script to set HTTP/HTTPS headers.\n" \
   "header-script-renew=<SECS> Time to renew HTTP/HTTPS headers.\n" \
   "http-version=none|...      Force a particular HTTP protocol.\n" \
+  "ipresolve=any|v4|v6        Force IPv4 or IPv6.\n" \
   "password=<PASSWORD>        The password for the user account.\n" \
   "protocols=PROTO,PROTO,..   Limit protocols allowed.\n" \
   "proxy=<PROXY>              Set proxy URL.\n" \
diff --git a/plugins/curl/curldefs.h b/plugins/curl/curldefs.h
index 2a74a369..815be2e1 100644
--- a/plugins/curl/curldefs.h
+++ b/plugins/curl/curldefs.h
@@ -61,6 +61,7 @@ extern struct curl_slist *headers;
 extern const char *header_script;
 extern unsigned header_script_renew;
 extern long http_version;
+extern long ipresolve;
 extern char *password;
 #ifndef HAVE_CURLOPT_PROTOCOLS_STR
 extern long protocols;
diff --git a/plugins/curl/nbdkit-curl-plugin.pod b/plugins/curl/nbdkit-curl-plugin.pod
index 070f9a0f..e12ca197 100644
--- a/plugins/curl/nbdkit-curl-plugin.pod
+++ b/plugins/curl/nbdkit-curl-plugin.pod
@@ -208,6 +208,19 @@ meaning curl will negotiate the best protocol with the server.  The
 other settings are mainly for testing.  See L<CURLOPT_HTTP_VERSION(3)>
 for details.
 
+=item B<ipresolve=any>
+
+=item B<ipresolve=v4>
+
+=item B<ipresolve=v6>
+
+(nbdkit E<ge> 1.36)
+
+Force curl to use only IPv4 (C<ipresolve=v4>), only IPv6
+(C<ipresolve=v6>) or any IP version supported by your system
+(C<ipresolve=any>).  The default is C<any>.  See
+L<CURLOPT_IPRESOLVE(3)>.
+
 =item B<password=>PASSWORD
 
 Set the password to use when connecting to the remote server.
@@ -559,6 +572,7 @@ L<CURLOPT_COOKIEFILE(3)>,
 L<CURLOPT_COOKIEJAR(3)>,
 L<CURLOPT_FOLLOWLOCATION(3)>,
 L<CURLOPT_HTTPHEADER(3)>,
+L<CURLOPT_IPRESOLVE(3)>,
 L<CURLOPT_PROXY(3)>,
 L<CURLOPT_SSL_CIPHER_LIST(3)>,
 L<CURLOPT_SSLVERSION(3)>,
diff --git a/plugins/curl/pool.c b/plugins/curl/pool.c
index 731dd367..f0c3cb4f 100644
--- a/plugins/curl/pool.c
+++ b/plugins/curl/pool.c
@@ -257,6 +257,8 @@ allocate_handle (void)
     curl_easy_setopt (ch->c, CURLOPT_HTTPHEADER, headers);
   if (http_version != CURL_HTTP_VERSION_NONE)
     curl_easy_setopt (ch->c, CURLOPT_HTTP_VERSION, (long) http_version);
+  if (ipresolve != CURL_IPRESOLVE_WHATEVER)
+    curl_easy_setopt (ch->c, CURLOPT_IPRESOLVE, (long) ipresolve);
 
   if (password)
     curl_easy_setopt (ch->c, CURLOPT_PASSWORD, password);
-- 
2.39.3