Only call on_prelude() when prelude passed crc check and limitation c… (

#29)
awslabs · Oct 9, 2019 · 32713d3 · 32713d3
1 parent 0d1e206
commit 32713d3
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/source/event_stream.c b/source/event_stream.c
@@ -1154,8 +1154,6 @@ static int s_verify_prelude_state(
     decoder->prelude.prelude_crc = aws_read_u32(decoder->working_buffer + PRELUDE_CRC_OFFSET);
     decoder->prelude.total_len = aws_read_u32(decoder->working_buffer + TOTAL_LEN_OFFSET);
 
-    decoder->on_prelude(decoder, &decoder->prelude, decoder->user_context);
-
     decoder->running_crc = aws_checksums_crc32(decoder->working_buffer, PRELUDE_CRC_OFFSET, 0);
 
     if (AWS_LIKELY(decoder->running_crc == decoder->prelude.prelude_crc)) {
@@ -1174,6 +1172,10 @@ static int s_verify_prelude_state(
             return AWS_OP_ERR;
         }
 
+        /* Should only call on_prelude() after passing crc check and limitation check, otherwise call on_prelude() with
+         * incorrect prelude is error prune. */
+        decoder->on_prelude(decoder, &decoder->prelude, decoder->user_context);
+
         decoder->running_crc = aws_checksums_crc32(
             decoder->working_buffer + PRELUDE_CRC_OFFSET,
             (int)sizeof(decoder->prelude.prelude_crc),