caddyfile: Do not replace import tokens if they are part of a snippet (#5539)

* fix variadic placeholder in imported file which also imports

* fix tests.

* skip replacing args when imported token may be part of a snippet

caddyconfig/caddyfile/parse.go

@@ -214,7 +214,7 @@ func (p *parser) addresses() error {
 
 		// special case: import directive replaces tokens during parse-time
 		if tkn == "import" && p.isNewLine() {
-			err := p.doImport()
+			err := p.doImport(0)
 			if err != nil {
 				return err
 			}
@@ -314,7 +314,7 @@ func (p *parser) directives() error {
 
 		// special case: import directive replaces tokens during parse-time
 		if p.Val() == "import" {
-			err := p.doImport()
+			err := p.doImport(1)
 			if err != nil {
 				return err
 			}
@@ -340,7 +340,7 @@ func (p *parser) directives() error {
 // is on the token before where the import directive was. In
 // other words, call Next() to access the first token that was
 // imported.
-func (p *parser) doImport() error {
+func (p *parser) doImport(nesting int) error {
 	// syntax checks
 	if !p.NextArg() {
 		return p.ArgErr()
@@ -443,10 +443,16 @@ func (p *parser) doImport() error {
 	// copy the tokens so we don't overwrite p.definedSnippets
 	tokensCopy := make([]Token, 0, len(importedTokens))
 
+	var (
+		maybeSnippet   bool
+		maybeSnippetId bool
+		index          int
+	)
+
 	// run the argument replacer on the tokens
 	// golang for range slice return a copy of value
 	// similarly, append also copy value
-	for _, token := range importedTokens {
+	for i, token := range importedTokens {
 		// set the token's file to refer to import directive line number and snippet name
 		if token.snippetName != "" {
 			token.updateFile(fmt.Sprintf("%s:%d (import %s)", token.File, p.Line(), token.snippetName))
@@ -454,6 +460,40 @@ func (p *parser) doImport() error {
 			token.updateFile(fmt.Sprintf("%s:%d (import)", token.File, p.Line()))
 		}
 
+		// naive way of determine snippets, as snippets definition can only follow name + block
+		// format, won't check for nesting correctness or any other error, that's what parser does.
+		if !maybeSnippet && nesting == 0 {
+			// first of the line
+			if i == 0 || importedTokens[i-1].originalFile() != token.originalFile() || importedTokens[i-1].Line+importedTokens[i-1].NumLineBreaks() < token.Line {
+				index = 0
+			} else {
+				index++
+			}
+
+			if index == 0 && len(token.Text) >= 3 && strings.HasPrefix(token.Text, "(") && strings.HasSuffix(token.Text, ")") {
+				maybeSnippetId = true
+			}
+		}
+
+		switch token.Text {
+		case "{":
+			nesting++
+			if index == 1 && maybeSnippetId && nesting == 1 {
+				maybeSnippet = true
+				maybeSnippetId = false
+			}
+		case "}":
+			nesting--
+			if nesting == 0 && maybeSnippet {
+				maybeSnippet = false
+			}
+		}
+
+		if maybeSnippet {
+			tokensCopy = append(tokensCopy, token)
+			continue
+		}
+
 		foundVariadic, startIndex, endIndex := parseVariadic(token, len(args))
 		if foundVariadic {
 			for _, arg := range args[startIndex:endIndex] {
@@ -553,7 +593,7 @@ func (p *parser) directive() error {
 		} else if p.Val() == "}" && p.nesting == 0 {
 			return p.Err("Unexpected '}' because no matching opening brace")
 		} else if p.Val() == "import" && p.isNewLine() {
-			if err := p.doImport(); err != nil {
+			if err := p.doImport(1); err != nil {
 				return err
 			}
 			p.cursor-- // cursor is advanced when we continue, so roll back one more

caddyconfig/httpcaddyfile/builtins_test.go

@@ -243,6 +243,27 @@ func TestImportErrorLine(t *testing.T) {
 				return err != nil && strings.Contains(err.Error(), "Caddyfile:5 (import t1):2")
 			},
 		},
+		{
+			input: `
+				import testdata/import_variadic_snippet.txt
+				:8080 {
+					import t1 true
+				}`,
+			errorFunc: func(err error) bool {
+				return err == nil
+			},
+		},
+		{
+			input: `
+				import testdata/import_variadic_with_import.txt
+				:8080 {
+					import t1 true
+					import t2 true
+				}`,
+			errorFunc: func(err error) bool {
+				return err == nil
+			},
+		},
 	} {
 		adapter := caddyfile.Adapter{
 			ServerType: ServerType{},

caddyconfig/httpcaddyfile/testdata/import_variadic.txt

@@ -0,0 +1,9 @@
+(t2) {
+    respond 200 {
+        body {args[:]}
+    }
+}
+
+:8082 {
+    import t2 false
+}

caddyconfig/httpcaddyfile/testdata/import_variadic_snippet.txt

@@ -0,0 +1,9 @@
+(t1) {
+    respond 200 {
+        body {args[:]}
+    }
+}
+
+:8081 {
+    import t1 false
+}

caddyconfig/httpcaddyfile/testdata/import_variadic_with_import.txt

@@ -0,0 +1,15 @@
+(t1) {
+    respond 200 {
+        body {args[:]}
+    }
+}
+
+:8081 {
+    import t1 false
+}
+
+import import_variadic.txt
+
+:8083 {
+    import t2 true
+}