Added ipresolve option

doc/man/s3fs.1.in

@@ -418,6 +418,12 @@ Username and passphrase are valid only for HTTP schema.
 If the HTTP proxy does not require authentication, this option is not required.
 Separate the username and passphrase with a ':' character and specify each as a URL-encoded string.
 .TP
+\fB\-o\fR ipresolve (default="whatever")
+Select what type of IP addresses to use when establishing a connection.
+Default('whatever') can use addresses of all IP versions(IPv4 and IPv6) that your system allows.
+If you specify 'IPv4', only IPv4 addresses are used.
+And when 'IPv6' is specified, only IPv6 addresses will be used.
+.TP
 \fB\-o\fR logfile - specify the log output file.
 s3fs outputs the log file to syslog. Alternatively, if s3fs is started with the "-f" option specified, the log will be output to the stdout/stderr.
 You can use this option to specify the log file that s3fs outputs.

src/curl.cpp

@@ -130,6 +130,7 @@ bool             S3fsCurl::requester_pays      = false;          // default
 std::string      S3fsCurl::proxy_url;
 bool             S3fsCurl::proxy_http          = false;
 std::string      S3fsCurl::proxy_userpwd;
+long             S3fsCurl::ipresolve_type      = CURL_IPRESOLVE_WHATEVER;
 
 //-------------------------------------------------------------------
 // Class methods for S3fsCurl
@@ -1174,6 +1175,23 @@ bool S3fsCurl::SetProxyUserPwd(const char* file)
     return true;
 }
 
+bool S3fsCurl::SetIPResolveType(const char* value)
+{
+    if(!value){
+        return false;
+    }
+    if(0 == strcasecmp(value, "ipv4")){
+        S3fsCurl::ipresolve_type = CURL_IPRESOLVE_V4;
+    }else if(0 == strcasecmp(value, "ipv6")){
+        S3fsCurl::ipresolve_type = CURL_IPRESOLVE_V6;
+    }else if(0 == strcasecmp(value, "whatever")){       // = default type
+        S3fsCurl::ipresolve_type = CURL_IPRESOLVE_WHATEVER;
+    }else{
+        return false;
+    }
+    return true;
+}
+
 // cppcheck-suppress unmatchedSuppression
 // cppcheck-suppress constParameter
 // cppcheck-suppress constParameterCallback
@@ -1949,7 +1967,11 @@ bool S3fsCurl::ResetHandle(AutoLock::Type locktype)
     if(CURLE_OK != curl_easy_setopt(hCurl, S3FS_CURLOPT_KEEP_SENDING_ON_ERROR, 1) && !run_once){
         S3FS_PRN_WARN("The S3FS_CURLOPT_KEEP_SENDING_ON_ERROR option could not be set. For maximize performance you need to enable this option and you should use libcurl 7.51.0 or later.");
     }
-
+    if(CURL_IPRESOLVE_WHATEVER != S3fsCurl::ipresolve_type){    // CURL_IPRESOLVE_WHATEVER is default, so not need to set.
+        if(CURLE_OK != curl_easy_setopt(hCurl, CURLOPT_IPRESOLVE, S3fsCurl::ipresolve_type)){
+            return false;
+        }
+    }
     if(type != REQTYPE::IAMCRED && type != REQTYPE::IAMROLE){
         // REQTYPE::IAMCRED and REQTYPE::IAMROLE are always HTTP
         if(0 == S3fsCurl::ssl_verify_hostname){

src/curl.h

@@ -156,6 +156,7 @@ class S3fsCurl
         static std::string      proxy_url;
         static bool             proxy_http;
         static std::string      proxy_userpwd;     // load from file(<username>:<passphrase>)
+        static long             ipresolve_type;    // this value is a libcurl symbol.
 
         // variables
         CURL*                hCurl;
@@ -340,6 +341,7 @@ class S3fsCurl
         static bool IsRequesterPays() { return S3fsCurl::requester_pays; }
         static bool SetProxy(const char* url);
         static bool SetProxyUserPwd(const char* userpwd);
+        static bool SetIPResolveType(const char* value);
 
         // methods
         bool CreateCurlHandle(bool only_pool = false, bool remake = false);

src/s3fs.cpp

@@ -5434,6 +5434,14 @@ static int my_fuse_opt_proc(void* data, const char* arg, int key, struct fuse_ar
             }
             return 0;
         }
+        else if(is_prefix(arg, "ipresolve=")){
+            const char* pipresolve = &arg[strlen("ipresolve=")];
+            if(!S3fsCurl::SetIPResolveType(pipresolve)){
+                S3FS_PRN_EXIT("failed to ip resolve option value(%s).", pipresolve);
+                return -1;
+            }
+            return 0;
+        }
         //
         // log file option
         //

src/s3fs_help.cpp

@@ -527,6 +527,14 @@ static constexpr char help_string[] =
     "        Separate the username and passphrase with a ':' character and\n"
     "        specify each as a URL-encoded string.\n"
     "\n"
+    "   ipresolve (default=\"whatever\")\n"
+    "        Select what type of IP addresses to use when establishing a\n"
+    "        connection.\n"
+    "        Default('whatever') can use addresses of all IP versions(IPv4 and\n"
+    "        IPv6) that your system allows. If you specify 'IPv4', only IPv4\n"
+    "        addresses are used. And when 'IPv6'is specified, only IPv6 addresses\n"
+    "        will be used.\n"
+    "\n"
     "   logfile - specify the log output file.\n"
     "        s3fs outputs the log file to syslog. Alternatively, if s3fs is\n"
     "        started with the \"-f\" option specified, the log will be output\n"