lib-mail: Change rfc822_parse_content_param() API to allow NULs in value

This was the only function in rfc822-parser.h that wasn't NUL-safe.
This won't fix anything, but it makes the rfc822-parser.h API fully
consistent with the NUL handling.

Normally rfc2231_parse() should be called instead of calling
rfc822_parse_content_param() directly, so this shouldn't break any plugins.

src/lib-mail/rfc2231-parser.c

@@ -43,7 +43,7 @@ int rfc2231_parse(struct rfc822_parser_context *ctx,
 	ARRAY(struct rfc2231_parameter) rfc2231_params_arr;
 	struct rfc2231_parameter rfc2231_param;
 	const struct rfc2231_parameter *rfc2231_params;
-	const char *key, *value, *p, *p2;
+	const char *key, *p, *p2;
 	string_t *str;
 	unsigned int i, j, count, next, next_idx;
 	bool ok, have_extended, broken = FALSE;
@@ -55,7 +55,8 @@ int rfc2231_parse(struct rfc822_parser_context *ctx,
 	i_zero(&rfc2231_param);
 	t_array_init(&result, 8);
 	t_array_init(&rfc2231_params_arr, 8);
-	while ((ret = rfc822_parse_content_param(ctx, &key, &value)) != 0) {
+	str = t_str_new(64);
+	while ((ret = rfc822_parse_content_param(ctx, &key, str)) != 0) {
 		if (ret < 0) {
 			/* try to continue anyway.. */
 			broken = TRUE;
@@ -85,12 +86,13 @@ int rfc2231_parse(struct rfc822_parser_context *ctx,
 				p = NULL;
 			else {
 				rfc2231_param.key = t_strdup_until(key, p2);
-				rfc2231_param.value = value;
+				rfc2231_param.value = t_strdup(str_c(str));
 				array_append(&rfc2231_params_arr,
 					     &rfc2231_param, 1);
 			}
 		}
 		if (p == NULL) {
+			const char *value = t_strdup(str_c(str));
 			array_append(&result, &key, 1);
 			array_append(&result, &value, 1);
 		}
@@ -111,7 +113,6 @@ int rfc2231_parse(struct rfc822_parser_context *ctx,
 	/* keys are now sorted primarily by their name and secondarily by
 	   their index. If any indexes are missing, fallback to assuming
 	   these aren't RFC 2231 encoded parameters. */
-	str = t_str_new(64);
 	for (i = 0; i < count; i = next) {
 		ok = TRUE;
 		have_extended = FALSE;
@@ -160,7 +161,7 @@ int rfc2231_parse(struct rfc822_parser_context *ctx,
 			key = rfc2231_params[i].key;
 			if (have_extended)
 				key = t_strconcat(key, "*", NULL);
-			value = t_strdup(str_c(str));
+			const char *value = t_strdup(str_c(str));
 			array_append(&result, &key, 1);
 			array_append(&result, &value, 1);
 		}

src/lib-mail/rfc822-parser.c

@@ -375,10 +375,9 @@ int rfc822_parse_content_type(struct rfc822_parser_context *ctx, string_t *str)
 }
 
 int rfc822_parse_content_param(struct rfc822_parser_context *ctx,
-			       const char **key_r, const char **value_r)
+			       const char **key_r, string_t *value)
 {
-	string_t *tmp;
-	size_t value_pos;
+	string_t *key;
 	int ret;
 
 	/* .. := *(";" parameter)
@@ -387,7 +386,7 @@ int rfc822_parse_content_param(struct rfc822_parser_context *ctx,
 	   value := token / quoted-string
 	*/
 	*key_r = NULL;
-	*value_r = NULL;
+	str_truncate(value, 0);
 
 	if (ctx->data >= ctx->end)
 		return 0;
@@ -398,11 +397,9 @@ int rfc822_parse_content_param(struct rfc822_parser_context *ctx,
 	if (rfc822_skip_lwsp(ctx) <= 0)
 		return -1;
 
-	tmp = t_str_new(64);
-	if (rfc822_parse_mime_token(ctx, tmp) <= 0)
+	key = t_str_new(64);
+	if (rfc822_parse_mime_token(ctx, key) <= 0)
 		return -1;
-	str_append_c(tmp, '\0');
-	value_pos = str_len(tmp);
 
 	if (*ctx->data != '=')
 		return -1;
@@ -411,21 +408,20 @@ int rfc822_parse_content_param(struct rfc822_parser_context *ctx,
 	if ((ret = rfc822_skip_lwsp(ctx)) <= 0) {
 		/* broken / no value */
 	} else if (*ctx->data == '"') {
-		ret = rfc822_parse_quoted_string(ctx, tmp);
+		ret = rfc822_parse_quoted_string(ctx, value);
 	} else if (ctx->data < ctx->end && *ctx->data == '=') {
 		/* workaround for broken input:
 		   name==?utf-8?b?...?= */
 		while (ctx->data < ctx->end && *ctx->data != ';' &&
 		       *ctx->data != ' ' && *ctx->data != '\t' &&
 		       *ctx->data != '\r' && *ctx->data != '\n') {
-			str_append_c(tmp, *ctx->data);
+			str_append_c(value, *ctx->data);
 			ctx->data++;
 		}
 	} else {
-		ret = rfc822_parse_mime_token(ctx, tmp);
+		ret = rfc822_parse_mime_token(ctx, value);
 	}
 
-	*key_r = str_c(tmp);
-	*value_r = *key_r + value_pos;
+	*key_r = str_c(key);
 	return ret < 0 ? -1 : 1;
 }

src/lib-mail/rfc822-parser.h

@@ -54,9 +54,10 @@ int rfc822_parse_domain(struct rfc822_parser_context *ctx, string_t *str);
 /* Parse Content-Type header's type/subtype. */
 int rfc822_parse_content_type(struct rfc822_parser_context *ctx, string_t *str);
 /* For Content-Type style parameter parsing. Expect ";" key "=" value.
-   value is unescaped if needed. The returned strings are allocated from data
-   stack. Returns 1 = key/value set, 0 = no more data, -1 = invalid input. */
+   value is unescaped if needed. The returned key is allocated from data
+   stack. The value string is truncated for each call. Returns 1 = key/value
+   set, 0 = no more data, -1 = invalid input. */
 int rfc822_parse_content_param(struct rfc822_parser_context *ctx,
-			       const char **key_r, const char **value_r);
+			       const char **key_r, string_t *value);
 
 #endif

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

@@ -49,16 +49,17 @@ static void test_rfc822_parse_content_param(void)
 		{ "key2", " \"(),/:;<=>?@[\\]" }
 	};
 	struct rfc822_parser_context parser;
-	const char *key, *value;
+	const char *key;
+	string_t *value = t_str_new(64);
 	unsigned int i = 0;
 	int ret;
 
 	test_begin("rfc822 parse content param");
 	rfc822_parser_init(&parser, (const void *)input, strlen(input), NULL);
-	while ((ret = rfc822_parse_content_param(&parser, &key, &value)) > 0 &&
+	while ((ret = rfc822_parse_content_param(&parser, &key, value)) > 0 &&
 	       i < N_ELEMENTS(output)) {
 		test_assert_idx(strcmp(output[i].key, key) == 0, i);
-		test_assert_idx(strcmp(output[i].value, value) == 0, i);
+		test_assert_idx(strcmp(output[i].value, str_c(value)) == 0, i);
 		i++;
 	}
 	rfc822_parser_deinit(&parser);