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MXS-1931: Remove use of gw_MySQL_get_next_packet

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The function implemented redundant functionality and replacement with
modutil_get_next_MySQL_packet was planned.

When faced with a packet header spread over multiple buffers, the packet
length calculation would read past the buffer end. This is fixed by taking
modutil_get_next_MySQL_packet into use.

Identical behavior to the old function is achieved by calling
gwbuf_make_contiguous for each packet to store them in a contiguous area
of memory. This should be either removed and only done when
RCAP_TYPE_CONTIGUOUS_INPUT is requested or be made an innate feature of
statement based routing.
This commit is contained in:
Markus Mäkelä
2018-06-18 20:42:23 +03:00
parent 45f39e7fdd
commit 8eaa265168
3 changed files with 18 additions and 120 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
include/maxscale/protocol/mysql.h
View File

@ -464,8 +464,6 @@ int mysql_send_custom_error(DCB *dcb, int sequence, int affected_rows, const cha
int mysql_send_standard_error(DCB *dcb, int sequence, int errnum, const char *msg);
int mysql_send_auth_error(DCB *dcb, int sequence, int affected_rows, const char* msg);
GWBUF* gw_MySQL_get_next_packet(GWBUF** p_readbuf);
GWBUF* gw_MySQL_get_packets(GWBUF** p_readbuf, int* npackets);
void protocol_add_srv_command(MySQLProtocol* p, mxs_mysql_cmd_t cmd);
void protocol_remove_srv_command(MySQLProtocol* p);
bool protocol_waits_response(MySQLProtocol* p);

42
server/modules/protocol/MySQL/mariadbclient/mysql_client.cc
View File

@ -1576,6 +1576,17 @@ static bool reauthenticate_client(MXS_SESSION* session, GWBUF* packetbuf)
return rval;
}
// Helper function for debug assertions
static bool only_one_packet(GWBUF* buffer)
{
ss_dassert(buffer);
uint8_t header[4] = {};
gwbuf_copy_data(buffer, 0, MYSQL_HEADER_LEN, header);
size_t packet_len = gw_mysql_get_byte3(header);
size_t buffer_len = gwbuf_length(buffer);
return packet_len + MYSQL_HEADER_LEN == buffer_len;
}
/**
* Detect if buffer includes partial mysql packet or multiple packets.
* Store partial packet to dcb_readqueue. Send complete packets one by one
@ -1597,15 +1608,15 @@ static int route_by_statement(MXS_SESSION* session, uint64_t capabilities, GWBUF
GWBUF* packetbuf;
do
{
/**
* Collect incoming bytes to a buffer until complete packet has
* arrived and then return the buffer.
*/
// TODO: This should be replaced with modutil_get_next_MySQL_packet.
packetbuf = gw_MySQL_get_next_packet(p_readbuf);
// Process client request one packet at a time
packetbuf = modutil_get_next_MySQL_packet(p_readbuf);
// TODO: Do this only when RCAP_TYPE_CONTIGUOUS_INPUT is requested
packetbuf = gwbuf_make_contiguous(packetbuf);
if (packetbuf != NULL)
{
ss_dassert(only_one_packet(packetbuf));
CHK_GWBUF(packetbuf);
MySQLProtocol* proto = (MySQLProtocol*)session->client_dcb->protocol;
@ -1619,24 +1630,7 @@ static int route_by_statement(MXS_SESSION* session, uint64_t capabilities, GWBUF
if (rcap_type_required(capabilities, RCAP_TYPE_CONTIGUOUS_INPUT))
{
if (!GWBUF_IS_CONTIGUOUS(packetbuf))
{
// TODO: As long as gw_MySQL_get_next_packet is used above, the buffer
// TODO: will be contiguous. That function should be replaced with
// TODO: modutil_get_next_MySQL_packet.
GWBUF* tmp = gwbuf_make_contiguous(packetbuf);
if (tmp)
{
packetbuf = tmp;
}
else
{
// TODO: A memory allocation failure. We should close the dcb
// TODO: and terminate the session.
rc = 0;
goto return_rc;
}
}
ss_dassert(GWBUF_IS_CONTIGUOUS(packetbuf));
if (rcap_type_required(capabilities, RCAP_TYPE_TRANSACTION_TRACKING))
{

94
server/modules/protocol/MySQL/mysql_common.cc
View File

@ -473,100 +473,6 @@ int mysql_send_auth_error(DCB *dcb,
return sizeof(mysql_packet_header) + mysql_payload_size;
}
/**
* Buffer contains at least one of the following:
* complete [complete] [partial] mysql packet
*
* @param p_readbuf Address of read buffer pointer
*
* @return pointer to gwbuf containing a complete packet or
* NULL if no complete packet was found.
*/
GWBUF* gw_MySQL_get_next_packet(GWBUF** p_readbuf)
{
GWBUF* packetbuf;
GWBUF* readbuf;
size_t buflen;
size_t packetlen;
size_t totalbuflen;
uint8_t* data;
size_t nbytes_copied = 0;
uint8_t* target;
readbuf = *p_readbuf;
if (readbuf == NULL)
{
packetbuf = NULL;
goto return_packetbuf;
}
CHK_GWBUF(readbuf);
if (GWBUF_EMPTY(readbuf))
{
packetbuf = NULL;
goto return_packetbuf;
}
totalbuflen = gwbuf_length(readbuf);
data = (uint8_t *)GWBUF_DATA((readbuf));
packetlen = MYSQL_GET_PAYLOAD_LEN(data) + 4;
/** packet is incomplete */
if (packetlen > totalbuflen)
{
packetbuf = NULL;
goto return_packetbuf;
}
packetbuf = gwbuf_alloc(packetlen);
target = GWBUF_DATA(packetbuf);
packetbuf->gwbuf_type = readbuf->gwbuf_type; /*< Copy the type too */
/**
* Copy first MySQL packet to packetbuf and leave posible other
* packets to read buffer.
*/
while (nbytes_copied < packetlen && totalbuflen > 0)
{
uint8_t* src = GWBUF_DATA((*p_readbuf));
size_t bytestocopy;
buflen = GWBUF_LENGTH((*p_readbuf));
bytestocopy = buflen < (packetlen - nbytes_copied) ? buflen : packetlen - nbytes_copied;
memcpy(target + nbytes_copied, src, bytestocopy);
*p_readbuf = gwbuf_consume((*p_readbuf), bytestocopy);
totalbuflen = gwbuf_length((*p_readbuf));
nbytes_copied += bytestocopy;
}
ss_dassert(buflen == 0 || nbytes_copied == packetlen);
return_packetbuf:
return packetbuf;
}
/**
* Move <npackets> from buffer pointed to by <*p_readbuf>.
* Appears to be unused 11 May 2016 (Martin)
*/
GWBUF* gw_MySQL_get_packets(GWBUF** p_srcbuf,
int* npackets)
{
GWBUF* packetbuf;
GWBUF* targetbuf = NULL;
while (*npackets > 0 && (packetbuf = gw_MySQL_get_next_packet(p_srcbuf)) != NULL)
{
targetbuf = gwbuf_append(targetbuf, packetbuf);
*npackets -= 1;
}
ss_dassert(*npackets < 128);
ss_dassert(*npackets >= 0);
return targetbuf;
}
static server_command_t* server_command_init(server_command_t* srvcmd,
mxs_mysql_cmd_t cmd)
{