Better URL validation (#1507)

* Add correct git branch name validation

* Change git refname validation error constant name

* Implement URL validation based on GoLang url.Parse method

* Backward compatibility with older Go compiler

* Add git reference name validation unit tests

* Remove unused variable in unit test

* Implement URL validation based on GoLang url.Parse method

* Backward compatibility with older Go compiler

* Add url validation unit tests

modules/validation/binding.go

@@ -0,0 +1,102 @@
+// Copyright 2017 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package validation
+
+import (
+	"fmt"
+	"net/url"
+	"regexp"
+	"strings"
+
+	"github.com/go-macaron/binding"
+)
+
+const (
+	// ErrGitRefName is git reference name error
+	ErrGitRefName = "GitRefNameError"
+)
+
+var (
+	// GitRefNamePattern is regular expression wirh unallowed characters in git reference name
+	GitRefNamePattern = regexp.MustCompile("[^\\d\\w-_\\./]")
+)
+
+// AddBindingRules adds additional binding rules
+func AddBindingRules() {
+	addGitRefNameBindingRule()
+	addValidURLBindingRule()
+}
+
+func addGitRefNameBindingRule() {
+	// Git refname validation rule
+	binding.AddRule(&binding.Rule{
+		IsMatch: func(rule string) bool {
+			return strings.HasPrefix(rule, "GitRefName")
+		},
+		IsValid: func(errs binding.Errors, name string, val interface{}) (bool, binding.Errors) {
+			str := fmt.Sprintf("%v", val)
+
+			if GitRefNamePattern.MatchString(str) {
+				errs.Add([]string{name}, ErrGitRefName, "GitRefName")
+				return false, errs
+			}
+			// Additional rules as described at https://www.kernel.org/pub/software/scm/git/docs/git-check-ref-format.html
+			if strings.HasPrefix(str, "/") || strings.HasSuffix(str, "/") ||
+				strings.HasPrefix(str, ".") || strings.HasSuffix(str, ".") ||
+				strings.HasSuffix(str, ".lock") ||
+				strings.Contains(str, "..") || strings.Contains(str, "//") {
+				errs.Add([]string{name}, ErrGitRefName, "GitRefName")
+				return false, errs
+			}
+
+			return true, errs
+		},
+	})
+}
+
+func addValidURLBindingRule() {
+	// URL validation rule
+	binding.AddRule(&binding.Rule{
+		IsMatch: func(rule string) bool {
+			return strings.HasPrefix(rule, "ValidUrl")
+		},
+		IsValid: func(errs binding.Errors, name string, val interface{}) (bool, binding.Errors) {
+			str := fmt.Sprintf("%v", val)
+			if len(str) != 0 {
+				if u, err := url.ParseRequestURI(str); err != nil ||
+					(u.Scheme != "http" && u.Scheme != "https") ||
+					!validPort(portOnly(u.Host)) {
+					errs.Add([]string{name}, binding.ERR_URL, "Url")
+					return false, errs
+				}
+			}
+
+			return true, errs
+		},
+	})
+}
+
+func portOnly(hostport string) string {
+	colon := strings.IndexByte(hostport, ':')
+	if colon == -1 {
+		return ""
+	}
+	if i := strings.Index(hostport, "]:"); i != -1 {
+		return hostport[i+len("]:"):]
+	}
+	if strings.Contains(hostport, "]") {
+		return ""
+	}
+	return hostport[colon+len(":"):]
+}
+
+func validPort(p string) bool {
+	for _, r := range []byte(p) {
+		if r < '0' || r > '9' {
+			return false
+		}
+	}
+	return true
+}