distribute: Make server work with multiple remote disks

This change initializes rpc servers associated with disks that are
local. It makes object layer initialization on demand, namely on the
first request to the object layer.

Also adds lock RPC service vendorized minio/dsync

cmd/object-common.go

@@ -17,7 +17,7 @@
 package cmd
 
 import (
-	"path/filepath"
+	"net"
 	"strings"
 	"sync"
 )
@@ -53,13 +53,57 @@ func fsHouseKeeping(storageDisk StorageAPI) error {
 	return nil
 }
 
+// Check if a network path is local to this node.
+func isLocalStorage(networkPath string) bool {
+	if idx := strings.LastIndex(networkPath, ":"); idx != -1 {
+		// e.g 10.0.0.1:9000:/mnt/networkPath
+		netAddr, _ := splitNetPath(networkPath)
+		var netHost string
+		var err error
+		netHost, _, err = net.SplitHostPort(netAddr)
+		if err != nil {
+			netHost = netAddr
+		}
+		// Resolve host to address to check if the IP is loopback.
+		// If address resolution fails, assume it's a non-local host.
+		addrs, err := net.LookupHost(netHost)
+		if err != nil {
+			return false
+		}
+		for _, addr := range addrs {
+			if ip := net.ParseIP(addr); ip.IsLoopback() {
+				return true
+			}
+		}
+		iaddrs, err := net.InterfaceAddrs()
+		if err != nil {
+			return false
+		}
+		for _, addr := range addrs {
+			for _, iaddr := range iaddrs {
+				ip, _, err := net.ParseCIDR(iaddr.String())
+				if err != nil {
+					return false
+				}
+				if ip.String() == addr {
+					return true
+				}
+
+			}
+		}
+		return false
+	}
+	return true
+}
+
 // Depending on the disk type network or local, initialize storage API.
 func newStorageAPI(disk string) (storage StorageAPI, err error) {
-	if !strings.ContainsRune(disk, ':') || filepath.VolumeName(disk) != "" {
-		// Initialize filesystem storage API.
+	if isLocalStorage(disk) {
+		if idx := strings.LastIndex(disk, ":"); idx != -1 {
+			return newPosix(disk[idx+1:])
+		}
 		return newPosix(disk)
 	}
-	// Initialize rpc client storage API.
 	return newRPCClient(disk)
 }