Ignore empty payload

src/aead.c

@@ -586,6 +586,9 @@ aead_chunk_decrypt(cipher_ctx_t *ctx, uint8_t *p, uint8_t *c, uint8_t *n,
     mlen = ntohs(*(uint16_t *)len_buf);
     mlen = mlen & CHUNK_SIZE_MASK;
 
+    if (mlen == 0)
+        return CRYPTO_ERROR;
+
     size_t chunk_len = 2 * tlen + CHUNK_SIZE_LEN + mlen;
 
     if (*clen < chunk_len)