fix message bound issues

server.c

@@ -288,6 +288,11 @@ ssize_t bus_client_recv(bus_t *s, int i, void *buf, size_t n)
 
 int bus_broadcast_message(bus_t *s, wire_message_t *msg, wire_context_t *ctx, char *sender_unique_name)
 {
+    uint32_t body_end = ctx->byte_cursor + msg->body_length;
+    if (body_end >= ctx->data_len) {
+        return -1;
+    }
+
     int left = s->clients_count;
     for (int i = 0; i < BUS_MAX_CLIENTS && left > 0; i++) {
         if (s->clients[i].match_count <= 0) {
@@ -320,6 +325,10 @@ int bus_broadcast_message(bus_t *s, wire_message_t *msg, wire_context_t *ctx, ch
             }
         }
     }
+
+    // We rely on the byte_cursor being at the end of the message upon processing.
+    ctx->byte_cursor = body_end;
+    
     return 0;
 }
 
@@ -330,12 +339,12 @@ int bus_unicast_message(bus_t *s, wire_message_t *msg, wire_context_t *ctx, char
         return -1;
     }
 
-    uint8_t reply_data[4096];
-    memset(reply_data, 0, 4096);
+    uint8_t reply_data[8192];
+    memset(reply_data, 0, 8192);
     wire_context_t reply_ctx = {
         .byte_cursor = 0,
         .data = reply_data,
-        .data_len = 4096,
+        .data_len = 8192,
     };
 
     TRYST(wire_compose_unicast_reply(&reply_ctx, ctx, msg, sender_unique_name));
@@ -511,6 +520,8 @@ int handle_remove_match(bus_t *s, int i, wire_message_t *msg, wire_context_t *ct
 int handle_get_connection_stats(bus_t *s, int i, wire_message_t *msg, wire_context_t *ctx, wire_context_t *reply_ctx) {
     (void)ctx;
 
+    TRYPTR(wire_get_name_string(ctx));
+
     // TODO: stub (always returns empty array)
     printf("FIXME: STUB: GetConnectionStats\n");
 
@@ -628,6 +639,11 @@ int bus_client_process_message(bus_t *s, int i, wire_context_t *ctx)
         return -1;
     }
 
+    uint32_t body_end = ctx->byte_cursor + msg.body_length;
+    if (body_end >= ctx->data_len) {
+        return -1;
+    }
+
     wire_message_field_t *destination_field = &msg.fields[DBUS_HEADER_FIELD_DESTINATION];
     wire_message_field_t *member_field = &msg.fields[DBUS_HEADER_FIELD_MEMBER];
 
@@ -645,12 +661,12 @@ int bus_client_process_message(bus_t *s, int i, wire_context_t *ctx)
             const bus_method_handler_t *handler = &bus_method_handlers[j];
             if (strcmp(handler->name, member_field->t.str) == 0) {
                 TRYST(handler->handler(s, i, &msg, ctx, &reply_ctx));
-                return 0;
+                goto end_nonfatal;
             }
         }
         printf("FIXME: daemon method '%s' is not implemented or invalid\n", member_field->t.str);
         _process_message_reply_error("org.freedesktop.DBus.Error.UnknownMethod");
-        return 0;
+        goto end_nonfatal;
     }
 
     // message needs to be routed
@@ -663,15 +679,32 @@ int bus_client_process_message(bus_t *s, int i, wire_context_t *ctx)
     if (destination_field->present) {
         if (bus_unicast_message(s, &msg, ctx, destination_field->t.str, s->names[client->unique_name_index].name) < 0) {
             _process_message_reply_error("xyz.hippoz.jitterbug.UnicastFailed");
-            return 0;
+            goto end_nonfatal;
         }
     } else {
         if (bus_broadcast_message(s, &msg, ctx, s->names[client->unique_name_index].name) < 0) {
             _process_message_reply_error("xyz.hippoz.jitterbug.BroadcastFailed");
-            return 0;
+            goto end_nonfatal;
         }
     }
 
+end_nonfatal:
+    if (ctx->byte_cursor != body_end) {
+        // The code above did not properly consume the entire message while parsing.
+        // This is bad, because we expect the byte_cursor after this function to be
+        // exactly at the end of a message. We rely on this invariant for message
+        // boundries. We can obviously just set the byte_cursor to the body_end
+        // that we have calculated and move on, however, not consuming the entire
+        // message is nonetheless a bug that should be fixed, or an indicator of
+        // another bug or something going wrong.
+        // In this case, I've decided to set the byte_cursor to the end of the
+        // body and print an error message. In the future, we may want to have
+        // separate debug builds, and maybe exit the program if we are in a
+        // debug build and we encounter something like this.
+        fprintf(stderr, "notice: parsing code did not consume the entire message (expected: %d, actual: %d)\n", body_end, ctx->byte_cursor);
+        ctx->byte_cursor = body_end;
+    }
+
     return 0;
 }
 
@@ -685,7 +718,8 @@ int bus_client_drain_messages(bus_t *s, int ci, uint8_t *data, uint32_t data_len
 
     TRYST(bus_client_process_message(s, ci, &ctx));
 
-    for (int i = 0; i < 10; i++) {
+    int i = 0;
+    for (; i < 10; i++) {
         if (ctx.byte_cursor >= ctx.data_len || ctx.data[ctx.byte_cursor] != 'l') {
             // no more messages
             break;
@@ -696,6 +730,8 @@ int bus_client_drain_messages(bus_t *s, int ci, uint8_t *data, uint32_t data_len
         TRYST(bus_client_process_message(s, ci, &ctx));
     }
 
+    printf("processed %d messages - cursor:%d; data_len:%ld\n", i + 1, ctx.byte_cursor, ctx.data_len);
+
     return 0;
 }
 
@@ -706,7 +742,7 @@ int bus_turn(bus_t *s)
     static const char auth_ok[] = "OK aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\r\n";
     static const char auth_list[] = "REJECTED EXTERNAL\r\n";
     static const char auth_data[] = "DATA\r\n";
-    static const int data_buffer_len = 8192;
+    static const int data_buffer_len = 16384;
 
     // We can keep a padding of null bytes for the data buffer. In the event that, for
     // example, a string function is called on a char array without a proper ending null

wire.c

@@ -383,6 +383,7 @@ int wire_compose_unicast_reply(wire_context_t *c, wire_context_t *msg_c, wire_me
 
     memcpy(&c->data[c->byte_cursor], &msg_c->data[msg_c->byte_cursor], msg->body_length);
     c->byte_cursor += msg->body_length;
+    msg_c->byte_cursor += msg->body_length;
 
     return 0;
 }