matchers: Drop forwarded option from remote_ip matcher (#6085)

Author: francislavoie

modules/caddyhttp/celmatcher_test.go

@@ -373,22 +373,6 @@ eqp31wM9il1n+guTNyxJd+FzVAH+hCZE5K+tCgVDdVFUlDEHHbS/wqb2PSIoouLV
 			urlTarget:  "https://example.com/foo",
 			wantResult: true,
 		},
-		{
-			name: "remote_ip forwarded (MatchRemoteIP)",
-			expression: &MatchExpression{
-				Expr: `remote_ip('forwarded', '192.0.2.1')`,
-			},
-			urlTarget:  "https://example.com/foo",
-			wantResult: true,
-		},
-		{
-			name: "remote_ip forwarded not first (MatchRemoteIP)",
-			expression: &MatchExpression{
-				Expr: `remote_ip('192.0.2.1', 'forwarded')`,
-			},
-			urlTarget: "https://example.com/foo",
-			wantErr:   true,
-		},
 	}
 )
 

modules/caddyhttp/ip_matchers.go

@@ -37,13 +37,6 @@ type MatchRemoteIP struct {
 	// The IPs or CIDR ranges to match.
 	Ranges []string `json:"ranges,omitempty"`
 
-	// If true, prefer the first IP in the request's X-Forwarded-For
-	// header, if present, rather than the immediate peer's IP, as
-	// the reference IP against which to match. Note that it is easy
-	// to spoof request headers. Default: false
-	// DEPRECATED: This is insecure, MatchClientIP should be used instead.
-	Forwarded bool `json:"forwarded,omitempty"`
-
 	// cidrs and zones vars should aligned always in the same
 	// length and indexes for matching later
 	cidrs  []*netip.Prefix
@@ -82,11 +75,7 @@ func (m *MatchRemoteIP) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 	d.Next() // consume matcher name
 	for d.NextArg() {
 		if d.Val() == "forwarded" {
-			if len(m.Ranges) > 0 {
-				return d.Err("if used, 'forwarded' must be first argument")
-			}
-			m.Forwarded = true
-			continue
+			return d.Err("the 'forwarded' option is no longer supported; use the 'client_ip' matcher instead")
 		}
 		if d.Val() == "private_ranges" {
 			m.Ranges = append(m.Ranges, PrivateRangesCIDR()...)
@@ -105,7 +94,7 @@ func (m *MatchRemoteIP) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 //
 // Example:
 //
-//	expression remote_ip('forwarded', '192.168.0.0/16', '172.16.0.0/12', '10.0.0.0/8')
+//	expression remote_ip('192.168.0.0/16', '172.16.0.0/12', '10.0.0.0/8')
 func (MatchRemoteIP) CELLibrary(ctx caddy.Context) (cel.Library, error) {
 	return CELMatcherImpl(
 		// name of the macro, this is the function name that users see when writing expressions.
@@ -126,11 +115,7 @@ func (MatchRemoteIP) CELLibrary(ctx caddy.Context) (cel.Library, error) {
 
 			for _, input := range strList.([]string) {
 				if input == "forwarded" {
-					if len(m.Ranges) > 0 {
-						return nil, errors.New("if used, 'forwarded' must be first argument")
-					}
-					m.Forwarded = true
-					continue
+					return nil, errors.New("the 'forwarded' option is no longer supported; use the 'client_ip' matcher instead")
 				}
 				m.Ranges = append(m.Ranges, input)
 			}
@@ -151,21 +136,12 @@ func (m *MatchRemoteIP) Provision(ctx caddy.Context) error {
 	m.cidrs = cidrs
 	m.zones = zones
 
-	if m.Forwarded {
-		m.logger.Warn("remote_ip's forwarded mode is deprecated; use the 'client_ip' matcher instead")
-	}
-
 	return nil
 }
 
 // Match returns true if r matches m.
 func (m MatchRemoteIP) Match(r *http.Request) bool {
 	address := r.RemoteAddr
-	if m.Forwarded {
-		if fwdFor := r.Header.Get("X-Forwarded-For"); fwdFor != "" {
-			address = strings.TrimSpace(strings.Split(fwdFor, ",")[0])
-		}
-	}
 	clientIP, zoneID, err := parseIPZoneFromString(address)
 	if err != nil {
 		m.logger.Error("getting remote IP", zap.Error(err))