1 files changed, 161 insertions, 0 deletions
diff --git a/modules/hostmatcher/hostmatcher.go b/modules/hostmatcher/hostmatcher.go
new file mode 100644
index 0000000..1069310
--- /dev/null
+++ b/modules/hostmatcher/hostmatcher.go
@@ -0,0 +1,161 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package hostmatcher
+
+import (
+	"net"
+	"path/filepath"
+	"strings"
+)
+
+// HostMatchList is used to check if a host or IP is in a list.
+type HostMatchList struct {
+	SettingKeyHint string
+	SettingValue   string
+
+	// builtins networks
+	builtins []string
+	// patterns for host names (with wildcard support)
+	patterns []string
+	// ipNets is the CIDR network list
+	ipNets []*net.IPNet
+}
+
+// MatchBuiltinExternal A valid non-private unicast IP, all hosts on public internet are matched
+const MatchBuiltinExternal = "external"
+
+// MatchBuiltinPrivate RFC 1918 (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) and RFC 4193 (FC00::/7). Also called LAN/Intranet.
+const MatchBuiltinPrivate = "private"
+
+// MatchBuiltinLoopback 127.0.0.0/8 for IPv4 and ::1/128 for IPv6, localhost is included.
+const MatchBuiltinLoopback = "loopback"
+
+func isBuiltin(s string) bool {
+	return s == MatchBuiltinExternal || s == MatchBuiltinPrivate || s == MatchBuiltinLoopback
+}
+
+// ParseHostMatchList parses the host list HostMatchList
+func ParseHostMatchList(settingKeyHint, hostList string) *HostMatchList {
+	hl := &HostMatchList{SettingKeyHint: settingKeyHint, SettingValue: hostList}
+	for _, s := range strings.Split(hostList, ",") {
+		s = strings.ToLower(strings.TrimSpace(s))
+		if s == "" {
+			continue
+		}
+		_, ipNet, err := net.ParseCIDR(s)
+		if err == nil {
+			hl.ipNets = append(hl.ipNets, ipNet)
+		} else if isBuiltin(s) {
+			hl.builtins = append(hl.builtins, s)
+		} else {
+			hl.patterns = append(hl.patterns, s)
+		}
+	}
+	return hl
+}
+
+// ParseSimpleMatchList parse a simple matchlist (no built-in networks, no CIDR support, only wildcard pattern match)
+func ParseSimpleMatchList(settingKeyHint, matchList string) *HostMatchList {
+	hl := &HostMatchList{
+		SettingKeyHint: settingKeyHint,
+		SettingValue:   matchList,
+	}
+	for _, s := range strings.Split(matchList, ",") {
+		s = strings.ToLower(strings.TrimSpace(s))
+		if s == "" {
+			continue
+		}
+		// we keep the same result as old `matchlist`, so no builtin/CIDR support here, we only match wildcard patterns
+		hl.patterns = append(hl.patterns, s)
+	}
+	return hl
+}
+
+// AppendBuiltin appends more builtins to match
+func (hl *HostMatchList) AppendBuiltin(builtin string) {
+	hl.builtins = append(hl.builtins, builtin)
+}
+
+// AppendPattern appends more pattern to match
+func (hl *HostMatchList) AppendPattern(pattern string) {
+	hl.patterns = append(hl.patterns, pattern)
+}
+
+// IsEmpty checks if the checklist is empty
+func (hl *HostMatchList) IsEmpty() bool {
+	return hl == nil || (len(hl.builtins) == 0 && len(hl.patterns) == 0 && len(hl.ipNets) == 0)
+}
+
+func (hl *HostMatchList) checkPattern(host string) bool {
+	host = strings.ToLower(strings.TrimSpace(host))
+	for _, pattern := range hl.patterns {
+		if matched, _ := filepath.Match(pattern, host); matched {
+			return true
+		}
+	}
+	return false
+}
+
+func (hl *HostMatchList) checkIP(ip net.IP) bool {
+	for _, pattern := range hl.patterns {
+		if pattern == "*" {
+			return true
+		}
+	}
+	for _, builtin := range hl.builtins {
+		switch builtin {
+		case MatchBuiltinExternal:
+			if ip.IsGlobalUnicast() && !ip.IsPrivate() {
+				return true
+			}
+		case MatchBuiltinPrivate:
+			if ip.IsPrivate() {
+				return true
+			}
+		case MatchBuiltinLoopback:
+			if ip.IsLoopback() {
+				return true
+			}
+		}
+	}
+	for _, ipNet := range hl.ipNets {
+		if ipNet.Contains(ip) {
+			return true
+		}
+	}
+	return false
+}
+
+// MatchHostName checks if the host matches an allow/deny(block) list
+func (hl *HostMatchList) MatchHostName(host string) bool {
+	if hl == nil {
+		return false
+	}
+
+	hostname, _, err := net.SplitHostPort(host)
+	if err != nil {
+		hostname = host
+	}
+	if hl.checkPattern(hostname) {
+		return true
+	}
+	if ip := net.ParseIP(hostname); ip != nil {
+		return hl.checkIP(ip)
+	}
+	return false
+}
+
+// MatchIPAddr checks if the IP matches an allow/deny(block) list, it's safe to pass `nil` to `ip`
+func (hl *HostMatchList) MatchIPAddr(ip net.IP) bool {
+	if hl == nil {
+		return false
+	}
+	host := ip.String() // nil-safe, we will get "<nil>" if ip is nil
+	return hl.checkPattern(host) || hl.checkIP(ip)
+}
+
+// MatchHostOrIP checks if the host or IP matches an allow/deny(block) list
+func (hl *HostMatchList) MatchHostOrIP(host string, ip net.IP) bool {
+	return hl.MatchHostName(host) || hl.MatchIPAddr(ip)
+}