Initial version

util.go

@@ -0,0 +1,127 @@
+package botfilter
+
+import (
+	"net"
+	"net/http"
+	"net/netip"
+	"net/url"
+	pathpkg "path"
+	"strings"
+)
+
+func clientIP(r *http.Request, cfg *compiledConfig) netip.Addr {
+	remote := parseRemoteAddress(r.RemoteAddr)
+	if cfg.clientIPHeader == "" || !addressInPrefixes(remote, cfg.trustedProxies) {
+		return remote
+	}
+
+	// A trusted reverse proxy must overwrite (not append to an untrusted
+	// client-provided value) this header. The left-most valid value is the
+	// original client in the conventional X-Forwarded-For representation.
+	for _, value := range strings.Split(r.Header.Get(cfg.clientIPHeader), ",") {
+		if addr, err := netip.ParseAddr(strings.TrimSpace(value)); err == nil {
+			return addr.Unmap()
+		}
+	}
+	return remote
+}
+
+func parseRemoteAddress(value string) netip.Addr {
+	host, _, err := net.SplitHostPort(strings.TrimSpace(value))
+	if err == nil {
+		value = host
+	}
+	addr, err := netip.ParseAddr(strings.Trim(strings.TrimSpace(value), "[]"))
+	if err != nil {
+		return netip.Addr{}
+	}
+	return addr.Unmap()
+}
+
+func addressInPrefixes(addr netip.Addr, prefixes []netip.Prefix) bool {
+	if !addr.IsValid() {
+		return false
+	}
+	for _, prefix := range prefixes {
+		if prefix.Contains(addr) {
+			return true
+		}
+	}
+	return false
+}
+
+func normaliseTokens(values []string) []string {
+	result := make([]string, 0, len(values))
+	for _, value := range values {
+		if token := strings.ToLower(strings.TrimSpace(value)); token != "" {
+			result = append(result, token)
+		}
+	}
+	return result
+}
+
+func normalisePaths(values []string) []string {
+	result := make([]string, 0, len(values))
+	for _, value := range values {
+		if path := normalisePath(value); path != "" {
+			result = append(result, path)
+		}
+	}
+	return result
+}
+
+func normaliseExtensions(values []string) []string {
+	result := make([]string, 0, len(values))
+	for _, value := range values {
+		value = strings.ToLower(strings.TrimSpace(value))
+		if value == "" {
+			continue
+		}
+		if !strings.HasPrefix(value, ".") {
+			value = "." + value
+		}
+		result = append(result, value)
+	}
+	return result
+}
+
+func normalisePath(value string) string {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return ""
+	}
+	value = strings.ReplaceAll(value, "\\", "/")
+	if !strings.HasPrefix(value, "/") {
+		value = "/" + value
+	}
+	return strings.ToLower(pathpkg.Clean(value))
+}
+
+func requestPaths(r *http.Request) []string {
+	values := []string{r.URL.Path, r.URL.EscapedPath()}
+	result := make([]string, 0, len(values)*3)
+	seen := make(map[string]struct{})
+	for _, value := range values {
+		for i := 0; i < 3 && value != ""; i++ {
+			normalised := normalisePath(value)
+			if _, ok := seen[normalised]; !ok {
+				seen[normalised] = struct{}{}
+				result = append(result, normalised)
+			}
+			decoded, err := url.PathUnescape(value)
+			if err != nil || decoded == value {
+				break
+			}
+			value = decoded
+		}
+	}
+	return result
+}
+
+func pathMatches(path, rule string) bool {
+	return path == rule || strings.HasPrefix(path, rule+"/")
+}
+
+func hasHeader(r *http.Request, name string) bool {
+	return strings.TrimSpace(r.Header.Get(name)) != ""
+}