add convenient functions in wire for getting strings with a limited length

server.c

@@ -383,13 +383,7 @@ int handle_hello(bus_t *s, int i, wire_message_t *msg, wire_context_t *ctx, wire
 }
 
 int handle_request_name(bus_t *s, int i, wire_message_t *msg, wire_context_t *ctx, wire_context_t *reply_ctx) {
-    char *name = TRYPTR(wire_get_string(ctx));
+    char *name = TRYPTR(wire_get_name_string(ctx));
-    int name_len = strlen(name);
-    if (name_len < 1 || name_len > 256) {
-        __TRY_TRACE();
-        return -1;
-    }
-
     char *name_str = TRYPTR(string_dup(name));
 
     int status_code = DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER;
@@ -411,11 +405,7 @@ int handle_request_name(bus_t *s, int i, wire_message_t *msg, wire_context_t *ct
 }
 
 int handle_get_name_owner(bus_t *s, int i, wire_message_t *msg, wire_context_t *ctx, wire_context_t *reply_ctx) {
-    char *name = TRYPTR(wire_get_string(ctx));
+    char *name = TRYPTR(wire_get_name_string(ctx));
-    int name_len = strlen(name);
-    if (name_len < 1 || name_len > 256) {
-        return -1;
-    }
 
     bus_client_t *target = bus_name_find_client(s, name);
     if (!target || target->unique_name_index < 0) {
@@ -430,11 +420,7 @@ int handle_get_name_owner(bus_t *s, int i, wire_message_t *msg, wire_context_t *
 }
 
 int handle_name_has_owner(bus_t *s, int i, wire_message_t *msg, wire_context_t *ctx, wire_context_t *reply_ctx) {
-    char *name = TRYPTR(wire_get_string(ctx));
+    char *name = TRYPTR(wire_get_name_string(ctx));
-    int name_len = strlen(name);
-    if (name_len < 1 || name_len > 256) {
-        return -1;
-    }
 
     bus_client_t *target = bus_name_find_client(s, name);
 
@@ -487,11 +473,8 @@ int handle_list_activatable_names(bus_t *s, int i, wire_message_t *msg, wire_con
 int handle_start_service_by_name(bus_t *s, int i, wire_message_t *msg, wire_context_t *ctx, wire_context_t *reply_ctx) {
     // TODO: stub (does nothing and always returns success)
 
-    char *name = TRYPTR(wire_get_string(ctx));
+    char *name = TRYPTR(wire_get_name_string(ctx));
-    int name_len = strlen(name);
+
-    if (name_len < 1 || name_len > 256) {
-        return -1;
-    }
     /* unused flags value */
     TRYPTR(wire_get_u32(ctx));
 
@@ -504,11 +487,7 @@ int handle_start_service_by_name(bus_t *s, int i, wire_message_t *msg, wire_cont
 }
 
 int handle_add_match(bus_t *s, int i, wire_message_t *msg, wire_context_t *ctx, wire_context_t *reply_ctx) {
-    char *match = TRYPTR(wire_get_string(ctx));
+    char *match = TRYPTR(wire_get_string_check(ctx, 1, MATCH_RULE_MAX));
-    int match_len = strlen(match);
-    if (match_len < 1 || match_len > MATCH_RULE_MAX) {
-        return -1;
-    }
 
     printf("client index %d adding match rule: '%s'\n", i, match);
 
@@ -521,11 +500,7 @@ int handle_add_match(bus_t *s, int i, wire_message_t *msg, wire_context_t *ctx,
 int handle_remove_match(bus_t *s, int i, wire_message_t *msg, wire_context_t *ctx, wire_context_t *reply_ctx) {
     // TODO: stub (does nothing and always returns success)
 
-    char *match = TRYPTR(wire_get_string(ctx));
+    char *match = TRYPTR(wire_get_string_check(ctx, 1, MATCH_RULE_MAX));
-    int match_len = strlen(match);
-    if (match_len < 1 || match_len > MATCH_RULE_MAX) {
-        return -1;
-    }
 
     printf("FIXME: STUB: RemoveMatch: %s\n", match);
 
@@ -549,11 +524,8 @@ int handle_get_connection_stats(bus_t *s, int i, wire_message_t *msg, wire_conte
 
 int handle_get_connection_unix_process_id(bus_t *s, int i, wire_message_t *msg, wire_context_t *ctx, wire_context_t *reply_ctx) {
     (void)ctx;
-    char *name = TRYPTR(wire_get_string(ctx));
+
-    int name_len = strlen(name);
+    char *name = TRYPTR(wire_get_name_string(ctx));
-    if (name_len < 1 || name_len > 256) {
-        return -1;
-    }
 
     bus_client_t *target = bus_name_find_client(s, name);
     if (!target || target->unique_name_index < 0 || target->fd < 0) {

wire.c

@@ -100,6 +100,13 @@ char *wire_set_string_impl(wire_context_t *c, const char *str, bool as_signature
     return dest;
 }
 
+char *wire_get_string_check(wire_context_t *c, int min_length, int max_length) {
+    char *str = TRYPTR_NIL(wire_get_string_impl(c, false));
+    int length = strlen(str);
+    if (length < min_length || length > max_length) return NULL;
+    return str;
+}
+
 int wire_parse_message(wire_context_t *c, wire_message_t *msg)
 {
     // SPEC: https://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-messages

wire.h

@@ -123,6 +123,7 @@ _WIRE_DECL_TYPE(boolean, uint32_t, 4);
 
 char *wire_get_string_impl(wire_context_t *c, bool as_signature);
 char *wire_set_string_impl(wire_context_t *c, const char *str, bool as_signature);
+char *wire_get_string_check(wire_context_t *c, int min_length, int max_length);
 int wire_parse_message(wire_context_t *c, wire_message_t *msg);
 int wire_compose_reply(wire_context_t *c, wire_message_t *msg, const char *signature, uint32_t **out_body_length);
 int wire_compose_error(wire_context_t *c, wire_message_t *msg, const char *error_name);
@@ -145,5 +146,10 @@ static inline char *wire_set_string(wire_context_t *c, const char *str) {
     return wire_set_string_impl(c, str, false);
 }
 
+// maximum name length is 255
+static inline char *wire_get_name_string(wire_context_t *c) {
+    return wire_get_string_check(c, 1, 255);
+}
+
 
 #endif // _JITTERBUG__WIRE_H