Support default values in placeholders

modules/caddyhttp/celmatcher_test.go

@@ -60,6 +60,15 @@ eqp31wM9il1n+guTNyxJd+FzVAH+hCZE5K+tCgVDdVFUlDEHHbS/wqb2PSIoouLV
 			urlTarget:         "https://example.com/foo",
 			wantResult:        true,
 		},
+		{
+			name: "boolean matches succeed for placeholder default",
+			expression: &MatchExpression{
+				Expr: "{unset:default} == 'default'",
+			},
+			clientCertificate: clientCert,
+			urlTarget:         "https://example.com/foo",
+			wantResult:        true,
+		},
 		{
 			name: "header matches (MatchHeader)",
 			expression: &MatchExpression{

modules/caddyhttp/replacer.go

@@ -62,31 +62,28 @@ func addHTTPVarsToReplacer(repl *caddy.Replacer, req *http.Request, w http.Respo
 		if req != nil {
 			// query string parameters
 			if strings.HasPrefix(key, reqURIQueryReplPrefix) {
-				vals := req.URL.Query()[key[len(reqURIQueryReplPrefix):]]
+				vals, found := req.URL.Query()[key[len(reqURIQueryReplPrefix):]]
 				// always return true, since the query param might
 				// be present only in some requests
-				return strings.Join(vals, ","), true
+				return strings.Join(vals, ","), found
 			}
 
 			// request header fields
 			if strings.HasPrefix(key, reqHeaderReplPrefix) {
 				field := key[len(reqHeaderReplPrefix):]
-				vals := req.Header[textproto.CanonicalMIMEHeaderKey(field)]
-				// always return true, since the header field might
-				// be present only in some requests
-				return strings.Join(vals, ","), true
+				vals, found := req.Header[textproto.CanonicalMIMEHeaderKey(field)]
+				return strings.Join(vals, ","), found
 			}
 
 			// cookies
 			if strings.HasPrefix(key, reqCookieReplPrefix) {
 				name := key[len(reqCookieReplPrefix):]
 				for _, cookie := range req.Cookies() {
 					if strings.EqualFold(name, cookie.Name) {
-						// always return true, since the cookie might
-						// be present only in some requests
 						return cookie.Value, true
 					}
 				}
+				return nil, false
 			}
 
 			// http.request.tls.*
@@ -161,7 +158,7 @@ func addHTTPVarsToReplacer(repl *caddy.Replacer, req *http.Request, w http.Respo
 				return id.String(), true
 			case "http.request.body":
 				if req.Body == nil {
-					return "", true
+					return "", false
 				}
 				// normally net/http will close the body for us, but since we
 				// are replacing it with a fake one, we have to ensure we close
@@ -219,11 +216,11 @@ func addHTTPVarsToReplacer(repl *caddy.Replacer, req *http.Request, w http.Respo
 				// convert to integer then compute prefix
 				bits, err := strconv.Atoi(bitsStr)
 				if err != nil {
-					return "", true
+					return "", false
 				}
 				prefix, err := addr.Prefix(bits)
 				if err != nil {
-					return "", true
+					return "", false
 				}
 				return prefix.String(), true
 			}
@@ -293,18 +290,16 @@ func addHTTPVarsToReplacer(repl *caddy.Replacer, req *http.Request, w http.Respo
 				raw := GetVar(req.Context(), varName)
 				// variables can be dynamic, so always return true
 				// even when it may not be set; treat as empty then
-				return raw, true
+				return raw, raw != nil
 			}
 		}
 
 		if w != nil {
 			// response header fields
 			if strings.HasPrefix(key, respHeaderReplPrefix) {
 				field := key[len(respHeaderReplPrefix):]
-				vals := w.Header()[textproto.CanonicalMIMEHeaderKey(field)]
-				// always return true, since the header field might
-				// be present only in some responses
-				return strings.Join(vals, ","), true
+				vals, found := w.Header()[textproto.CanonicalMIMEHeaderKey(field)]
+				return strings.Join(vals, ","), found
 			}
 		}
 

modules/caddyhttp/replacer_test.go

@@ -107,10 +107,6 @@ eqp31wM9il1n+guTNyxJd+FzVAH+hCZE5K+tCgVDdVFUlDEHHbS/wqb2PSIoouLV
 			get:    "http.request.remote.host/24,32",
 			expect: "192.168.159.0/24",
 		},
-		{
-			get:    "http.request.remote.host/999",
-			expect: "",
-		},
 		{
 			get:    "http.request.remote.port",
 			expect: "1234",
@@ -207,7 +203,7 @@ eqp31wM9il1n+guTNyxJd+FzVAH+hCZE5K+tCgVDdVFUlDEHHbS/wqb2PSIoouLV
 	} {
 		actual, got := repl.GetString(tc.get)
 		if !got {
-			t.Errorf("Test %d: Expected to recognize the placeholder name, but didn't", i)
+			t.Errorf("Test %d: Expected to recognize the placeholder name %q, but didn't", i, tc.get)
 		}
 		if actual != tc.expect {
 			t.Errorf("Test %d: Expected %s to be '%s' but got '%s'",