From 0f69b9b433403e11e811426b619addb515d87b5d Mon Sep 17 00:00:00 2001
From: hippoz <10706925-hippoz@users.noreply.gitlab.com>
Date: Sun, 22 Jan 2023 18:18:57 +0200
Subject: [PATCH] improve unique name writing

---
 server.c |  8 ++++----
 wire.c   | 22 +++++++++++++++++++++-
 wire.h   |  3 +++
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/server.c b/server.c
index 269c824..6a11171 100644
--- a/server.c
+++ b/server.c
@@ -215,18 +215,18 @@ BusName *bus_client_assign_unique_name(Bus *s, BusClient *client)
     if (client->unique_name) {
         return NULL;
     }
-    uint32_t id = 0;
+    uint8_t id = 0;
 
-    if (read(s->urandom_fd, &id, sizeof(uint32_t)) != sizeof(uint32_t)) {
+    if (read(s->urandom_fd, &id, sizeof(uint8_t)) != sizeof(uint8_t)) {
         return NULL;
     }
 
-    char *name_str = malloc(sizeof(char) * 16);
+    char *name_str = malloc(sizeof(char) * UNIQUE_NAME_LENGTH);
     if (!name_str) {
         return NULL;
     }
 
-    if (snprintf(name_str, 16, ":1.%"PRIu32, id) < 0) {
+    if (snprintf(name_str, UNIQUE_NAME_LENGTH, ":%05"PRIu16".%03"PRIu8, client->fd_index, id) != (UNIQUE_NAME_LENGTH - 1)) {
         free(name_str);
         return NULL;
     }
diff --git a/wire.c b/wire.c
index 63e2ed4..c728877 100644
--- a/wire.c
+++ b/wire.c
@@ -86,6 +86,26 @@ char *wire_get_string_impl(WireCtx *c, bool as_signature)
     return str;
 }
 
+char *wire_set_string_fixed(WireCtx *c, const char *str, uint32_t len)
+{
+    // len includes the null byte
+
+    TRYPTR_NIL(wire_set_u32(c, len - 1));
+
+    uint32_t new_cursor = c->byte_cursor + len;
+    if (unlikely(new_cursor >= c->data_len)) {
+        return NULL;
+    }
+
+    // TODO?
+    char *dest = (char*)&c->data[c->byte_cursor];
+    memcpy(dest, str, len);
+
+    c->byte_cursor = new_cursor; 
+
+    return dest;
+}
+
 char *wire_set_string_impl(WireCtx *c, const char *str, bool as_signature)
 {
     uint32_t len = strlen(str);
@@ -435,7 +455,7 @@ int wire_compose_unicast_reply(WireCtx *msg_c, WireMsg *msg, char *sender_unique
 
     TRYPTR(wire_set_u8(header_ctx, DBUS_HEADER_FIELD_SENDER));
     TRYPTR(wire_set_signature_single_char(header_ctx, 's'));
-    TRYPTR(wire_set_string(header_ctx, sender_unique_name));
+    TRYPTR(wire_set_string_fixed(header_ctx, sender_unique_name, UNIQUE_NAME_LENGTH));
     TRYPTR(wire_write_align(header_ctx, 8));
 
     *header_fields_length = header_ctx->byte_cursor - header_fields_start + msg->header_fields_length;
diff --git a/wire.h b/wire.h
index 447d270..abd3d4c 100644
--- a/wire.h
+++ b/wire.h
@@ -20,6 +20,8 @@
 #define DBUS_FLAG_NO_AUTO_START 0x1
 #define DBUS_FLAG_ALLOW_INTERACTIVE_AUTHORIZATION 0x1
 
+#define UNIQUE_NAME_LENGTH 11
+
 enum {
     DBUS_HEADER_FIELD_INVALID = 0,
     DBUS_HEADER_FIELD_PATH,
@@ -126,6 +128,7 @@ _WIRE_DECL_TYPE(boolean, uint32_t, 4)
 char *wire_get_string_impl(WireCtx *c, bool as_signature);
 char *wire_set_string_impl(WireCtx *c, const char *str, bool as_signature);
 char *wire_get_string_check(WireCtx *c, int min_length, int max_length);
+char *wire_set_string_fixed(WireCtx *c, const char *str, uint32_t len);
 int wire_parse_message(WireCtx *c, WireMsg *msg);
 int wire_compose_reply(WireCtx *c, WireMsg *msg, const char *signature, uint32_t **out_body_length);
 int wire_compose_error(WireCtx *c, WireMsg *msg, const char *error_name);