Add Allow-/Block-List for Migrate & Mirrors (#13610)

* add black list and white list support for migrating repositories

* fix fmt

* fix lint

* fix vendor

* fix modules.txt

* clean diff

* specify log message

* use blocklist/allowlist

* allways use lowercase to match url

* Apply allow/block

* Settings: use existing "migrations" section

* convert domains lower case

* dont store unused value

* Block private addresses for migration by default

* fix lint

* use proposed-upstream func to detect private IP addr

* a nit

* add own error for blocked migration, add tests, imprufe api

* fix test

* fix-if-localhost-is-ipv4

* rename error & error message

* rename setting options

* Apply suggestions from code review

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

modules/matchlist/matchlist.go

@@ -0,0 +1,46 @@
+// Copyright 2019 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 matchlist
+
+import (
+	"strings"
+
+	"github.com/gobwas/glob"
+)
+
+// Matchlist represents a block or allow list
+type Matchlist struct {
+	ruleGlobs []glob.Glob
+}
+
+// NewMatchlist creates a new block or allow list
+func NewMatchlist(rules ...string) (*Matchlist, error) {
+	for i := range rules {
+		rules[i] = strings.ToLower(rules[i])
+	}
+	list := Matchlist{
+		ruleGlobs: make([]glob.Glob, 0, len(rules)),
+	}
+
+	for _, rule := range rules {
+		rg, err := glob.Compile(rule)
+		if err != nil {
+			return nil, err
+		}
+		list.ruleGlobs = append(list.ruleGlobs, rg)
+	}
+
+	return &list, nil
+}
+
+// Match will matches
+func (b *Matchlist) Match(u string) bool {
+	for _, r := range b.ruleGlobs {
+		if r.Match(u) {
+			return true
+		}
+	}
+	return false
+}