lib-mail: rfc822-parser: Strip away folding whitespace from comments

src/lib-mail/rfc822-parser.c

@@ -64,6 +64,7 @@ void rfc822_parser_init(struct rfc822_parser_context *ctx,
 int rfc822_skip_comment(struct rfc822_parser_context *ctx)
 {
 	const unsigned char *start;
+	size_t len;
 	int level = 1;
 
 	i_assert(*ctx->data == '(');
@@ -87,16 +88,33 @@ int rfc822_skip_comment(struct rfc822_parser_context *ctx)
 				return ctx->data < ctx->end ? 1 : 0;
 			}
 			break;
-		case '\\':
-			if (ctx->last_comment != NULL) {
-				str_append_data(ctx->last_comment, start,
-						ctx->data - start);
-			}
+		case '\n':
+			/* folding whitespace, remove the (CR)LF */
+			if (ctx->last_comment == NULL)
+				break;
+			len = ctx->data - start;
+			if (len > 0 && start[len-1] == '\r')
+				len--;
+			str_append_data(ctx->last_comment, start, len);
 			start = ctx->data + 1;
-
+			break;
+		case '\\':
 			ctx->data++;
 			if (ctx->data >= ctx->end)
 				return -1;
+
+			if (*ctx->data == '\r' || *ctx->data == '\n') {
+				/* quoted-pair doesn't allow CR/LF.
+				   They are part of the obs-qp though, so don't
+				   return them as error. */
+				ctx->data--;
+				break;
+			}
+			if (ctx->last_comment != NULL) {
+				str_append_data(ctx->last_comment, start,
+						ctx->data - start - 1);
+			}
+			start = ctx->data;
 			break;
 		}
 	}

src/lib-mail/test-rfc822-parser.c

@@ -5,6 +5,51 @@
 #include "rfc822-parser.h"
 #include "test-common.h"
 
+static void test_rfc822_parse_comment(void)
+{
+	static const struct {
+		const char *input, *output;
+		int ret;
+	} tests[] = {
+		{ "(", "", -1 },
+		{ "(()", "", -1 },
+
+		{ "()", "", 0 },
+		{ "(())", "()", 0 },
+		{ "(foo ( bar ) baz)", "foo ( bar ) baz", 0 },
+		{ "(foo\t\tbar)", "foo\t\tbar", 0 },
+		{ "(foo\\(bar)", "foo(bar", 0 },
+		{ "(foo\\\\bar)", "foo\\bar", 0 },
+		{ "(foo\\\\\\\\)", "foo\\\\", 0 },
+		{ "(foo\\)bar)", "foo)bar", 0 },
+		{ "(foo\"flop\"\"bar)", "foo\"flop\"\"bar", 0 },
+
+		{ "(foo\n bar)", "foo bar", 0 },
+		{ "(foo\n\t\t bar)", "foo\t\t bar", 0 },
+		{ "(foo\\\n bar)", "foo\\ bar", 0 },
+		{ "(foo\\\r\n bar)", "foo\\ bar", 0 },
+	};
+	struct rfc822_parser_context parser, parser2;
+	string_t *str = t_str_new(64);
+	unsigned int i = 0;
+
+	test_begin("rfc822 parse comment");
+	for (i = 0; i < N_ELEMENTS(tests); i++) {
+		rfc822_parser_init(&parser, (const void *)tests[i].input,
+				   strlen(tests[i].input), str);
+		rfc822_parser_init(&parser2, (const void *)tests[i].input,
+				   strlen(tests[i].input), NULL);
+		test_assert_idx(rfc822_skip_comment(&parser) == tests[i].ret, i);
+		test_assert_idx(rfc822_skip_comment(&parser2) == tests[i].ret, i);
+		test_assert_idx(tests[i].ret < 0 ||
+				strcmp(tests[i].output, str_c(str)) == 0, i);
+		rfc822_parser_deinit(&parser);
+		rfc822_parser_deinit(&parser2);
+		str_truncate(str, 0);
+	}
+	test_end();
+}
+
 static void test_rfc822_parse_quoted_string(void)
 {
 	static const struct {
@@ -108,6 +153,7 @@ static void test_rfc822_parse_content_param(void)
 int main(void)
 {
 	static void (*const test_functions[])(void) = {
+		test_rfc822_parse_comment,
 		test_rfc822_parse_quoted_string,
 		test_rfc822_parse_domain_literal,
 		test_rfc822_parse_content_param,