Add X-Forwarded-For IP to the client's remote address

Instead of replacing connection's host with value specified by
this header, we will simply add the address to the logging only.
So instead of having something like:
```
192.168.1.1:5678 - wid:10 - Client connection created
```
we could have:
```
1.2.3.4/192.168.1.1:5678 - wid:10 - Client connection created
```
As seen above, this PR simply prefixes the connection's remote address
with the header's value (if a valid IP).

Related to #2734
Resolves #2767

Signed-off-by: Ivan Kozlovic <ivan@synadia.com>

server/client.go

@@ -610,12 +610,15 @@ func (c *client) initClient() {
 			if conn = addr.String(); conn != _EMPTY_ {
 				host, port, _ := net.SplitHostPort(conn)
 				iPort, _ := strconv.Atoi(port)
-				c.port = uint16(iPort)
+				c.host, c.port = host, uint16(iPort)
 				if c.isWebsocket() && c.ws.clientIP != _EMPTY_ {
-					c.host = c.ws.clientIP
-					conn = net.JoinHostPort(c.host, port)
-				} else {
-					c.host = host
+					cip := c.ws.clientIP
+					// Surround IPv6 addresses with square brackets, as
+					// net.JoinHostPort would do...
+					if strings.Contains(cip, ":") {
+						cip = "[" + cip + "]"
+					}
+					conn = fmt.Sprintf("%s/%s", cip, conn)
 				}
 				// Now that we have extracted host and port, escape
 				// the string because it is going to be used in Sprintf

server/websocket_test.go

@@ -3989,12 +3989,12 @@ func TestWSXForwardedFor(t *testing.T) {
 			}
 			select {
 			case d := <-l.ch:
-				ipAndColumn := fmt.Sprintf("%s:", test.expectedValue)
+				ipAndSlash := fmt.Sprintf("%s/", test.expectedValue)
 				if test.useHdrValue {
-					if !strings.HasPrefix(d, ipAndColumn) {
-						t.Fatalf("Expected debug statement to start with: %q, got %q", ipAndColumn, d)
+					if !strings.HasPrefix(d, ipAndSlash) {
+						t.Fatalf("Expected debug statement to start with: %q, got %q", ipAndSlash, d)
 					}
-				} else if strings.HasPrefix(d, ipAndColumn) {
+				} else if strings.HasPrefix(d, ipAndSlash) {
 					t.Fatalf("Unexpected debug statement: %q", d)
 				}
 			case <-time.After(time.Second):