Fix MySQL DSN -> tags parsing

Closes #297

plugins/mysql/parse_dsn.go

@@ -0,0 +1,85 @@
+// Copyright 2012 The Go-MySQL-Driver Authors. All rights reserved.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package mysql
+
+import (
+	"errors"
+	"strings"
+)
+
+// parseDSN parses the DSN string to a config
+func parseDSN(dsn string) (string, error) {
+	//var user, passwd string
+	var addr, net string
+
+	// [user[:password]@][net[(addr)]]/dbname[?param1=value1&paramN=valueN]
+	// Find the last '/' (since the password or the net addr might contain a '/')
+	for i := len(dsn) - 1; i >= 0; i-- {
+		if dsn[i] == '/' {
+			var j, k int
+
+			// left part is empty if i <= 0
+			if i > 0 {
+				// [username[:password]@][protocol[(address)]]
+				// Find the last '@' in dsn[:i]
+				for j = i; j >= 0; j-- {
+					if dsn[j] == '@' {
+						// username[:password]
+						// Find the first ':' in dsn[:j]
+						for k = 0; k < j; k++ {
+							if dsn[k] == ':' {
+								//passwd = dsn[k+1 : j]
+								break
+							}
+						}
+						//user = dsn[:k]
+
+						break
+					}
+				}
+
+				// [protocol[(address)]]
+				// Find the first '(' in dsn[j+1:i]
+				for k = j + 1; k < i; k++ {
+					if dsn[k] == '(' {
+						// dsn[i-1] must be == ')' if an address is specified
+						if dsn[i-1] != ')' {
+							if strings.ContainsRune(dsn[k+1:i], ')') {
+								return "", errors.New("Invalid DSN unescaped")
+							}
+							return "", errors.New("Invalid DSN Addr")
+						}
+						addr = dsn[k+1 : i-1]
+						break
+					}
+				}
+				net = dsn[j+1 : k]
+			}
+
+			break
+		}
+	}
+
+	// Set default network if empty
+	if net == "" {
+		net = "tcp"
+	}
+
+	// Set default address if empty
+	if addr == "" {
+		switch net {
+		case "tcp":
+			addr = "127.0.0.1:3306"
+		case "unix":
+			addr = "/tmp/mysql.sock"
+		default:
+			return "", errors.New("Default addr for network '" + net + "' unknown")
+		}
+	}
+
+	return addr, nil
+}