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MXS-1555: Never explicitly assign the readqueue

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The readqueue should never be explicitly assigned and should only ever be
appended to. This guarantees that the packets are read and processed in
the correct order.

Also removed an unused function that deals with the readqueue
manipulation.
This commit is contained in:
Markus Mäkelä
2017-12-05 09:24:31 +02:00
parent 6f185ff5db
commit 97d41e6ca0
1 changed files with 6 additions and 52 deletions
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58
server/modules/protocol/MySQL/MySQLClient/mysql_client.c
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@ -916,12 +916,13 @@ gw_read_normal_data(DCB *dcb, GWBUF *read_buffer, int nbytes_read)
* that is tracked by the protocol module is updated in route_by_statement() */
if (rcap_type_required(capabilities, RCAP_TYPE_STMT_INPUT))
{
if (nbytes_read < 3 || nbytes_read <
(MYSQL_GET_PAYLOAD_LEN((uint8_t *) GWBUF_DATA(read_buffer)) + 4))
uint8_t pktlen[MYSQL_HEADER_LEN];
size_t n_copied = gwbuf_copy_data(read_buffer, 0, MYSQL_HEADER_LEN, pktlen);
if (n_copied != sizeof(pktlen) ||
nbytes_read < MYSQL_GET_PAYLOAD_LEN(pktlen) + MYSQL_HEADER_LEN)
{
dcb->dcb_readqueue = read_buffer;
dcb->dcb_readqueue = gwbuf_append(dcb->dcb_readqueue, read_buffer);
return 0;
}
gwbuf_set_type(read_buffer, GWBUF_TYPE_MYSQL);
@ -1624,50 +1625,3 @@ static int route_by_statement(MXS_SESSION* session, uint64_t capabilities, GWBUF
return_rc:
return rc;
}
/**
* if read queue existed appent read to it. if length of read buffer is less
* than 3 or less than mysql packet then return. else copy mysql packets to
* separate buffers from read buffer and continue. else if read queue didn't
* exist, length of read is less than 3 or less than mysql packet then
* create read queue and append to it and return. if length read is less than
* mysql packet length append to read queue append to it and return.
* else (complete packet was read) continue.
*
* @return True if we have a complete packet, otherwise false
*/
static bool ensure_complete_packet(DCB *dcb, GWBUF **read_buffer, int nbytes_read)
{
if (dcb->dcb_readqueue)
{
dcb->dcb_readqueue = gwbuf_append(dcb->dcb_readqueue, *read_buffer);
nbytes_read = gwbuf_length(dcb->dcb_readqueue);
int plen = MYSQL_GET_PAYLOAD_LEN((uint8_t *) GWBUF_DATA(dcb->dcb_readqueue));
if (nbytes_read < 3 || nbytes_read < plen + 4)
{
return false;
}
else
{
/**
* There is at least one complete mysql packet in
* read_buffer.
*/
*read_buffer = dcb->dcb_readqueue;
dcb->dcb_readqueue = NULL;
}
}
else
{
uint8_t* data = (uint8_t *) GWBUF_DATA(*read_buffer);
if (nbytes_read < 3 || nbytes_read < MYSQL_GET_PAYLOAD_LEN(data) + 4)
{
dcb->dcb_readqueue = gwbuf_append(dcb->dcb_readqueue, *read_buffer);
return false;
}
}
return true;
}