hcq/MaxScale
hcq/MaxScale
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Fix readwritesplit handling of unexpected responses

Browse Source 
The backend server can send a response even if the client hasn't sent a
request. One case where this occurs is when the server is shutting
down. The internal logic of readwritesplit can't handle unexpected states
gracefully so the safest thing to do is to just ignore them and send the
responses to the client.
This commit is contained in:
Markus Mäkelä 2017-07-31 23:29:48 +03:00
parent 542f3b69db
commit 782b8db2aa
3 changed files with 67 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
include/maxscale/protocol/mysql.h
View File

@ -454,9 +454,22 @@ mxs_auth_state_t gw_send_backend_auth(DCB *dcb);
/** Write an OK packet to a DCB */
int mxs_mysql_send_ok(DCB *dcb, int sequence, uint8_t affected_rows, const char* message);
/** Check for OK packet */
/**
* @brief Check if the buffer contains an OK packet
*
* @param buffer Buffer containing a complete MySQL packet
* @return True if the buffer contains an OK packet
*/
bool mxs_mysql_is_ok_packet(GWBUF *buffer);
/**
* @brief Check if the buffer contains an ERR packet
*
* @param buffer Buffer containing a complete MySQL packet
* @return True if the buffer contains an ERR packet
*/
bool mxs_mysql_is_err_packet(GWBUF *buffer);
/**
* @brief Check if a buffer contains a result set
*

23
server/modules/protocol/MySQL/mysql_common.c
View File

@ -1498,23 +1498,18 @@ bool gw_read_backend_handshake(DCB *dcb, GWBUF *buffer)
return rval;
}
/**
* @brief Check if the buffer contains an OK packet
*
* @param buffer Buffer containing a complete MySQL packet
* @return True if the buffer contains an OK packet
*/
bool mxs_mysql_is_ok_packet(GWBUF *buffer)
{
bool rval = false;
uint8_t cmd;
uint8_t cmd = 0xff; // Default should differ from the OK packet
gwbuf_copy_data(buffer, MYSQL_HEADER_LEN, 1, &cmd);
return cmd == MYSQL_REPLY_OK;
}
if (gwbuf_copy_data(buffer, MYSQL_HEADER_LEN, 1, &cmd) && cmd == MYSQL_REPLY_OK)
{
rval = true;
}
return rval;
bool mxs_mysql_is_err_packet(GWBUF *buffer)
{
uint8_t cmd = 0x00; // Default should differ from the ERR packet
gwbuf_copy_data(buffer, MYSQL_HEADER_LEN, 1, &cmd);
return cmd == MYSQL_REPLY_ERR;
}
bool mxs_mysql_is_result_set(GWBUF *buffer)

45
server/modules/routing/readwritesplit/readwritesplit.cc
View File

@ -1076,6 +1076,40 @@ static json_t* diagnostics_json(const MXS_ROUTER *instance)
return rval;
}
static void log_unexpected_response(DCB* dcb, GWBUF* buffer)
{
if (mxs_mysql_is_err_packet(buffer))
{
/** This should be the only valid case where the server sends a response
* without the client sending one first. MaxScale does not yet advertise
* the progress reporting flag so we don't need to handle it. */
uint8_t* data = GWBUF_DATA(buffer);
size_t len = MYSQL_GET_PAYLOAD_LEN(data);
uint16_t errcode = MYSQL_GET_ERRCODE(data);
std::string errstr((char*)data + 7, (char*)data + 7 + len - 3);
if (errcode == ER_CONNECTION_KILLED)
{
MXS_INFO("Connection from '%s'@'%s' to '%s' was killed",
dcb->session->client_dcb->user,
dcb->session->client_dcb->remote,
dcb->server->unique_name);
}
else
{
MXS_WARNING("Server '%s' sent an unexpected error: %hu, %s",
dcb->server->unique_name, errcode, errstr.c_str());
}
}
else
{
MXS_ERROR("Unexpected internal state: received response 0x%02hhx from "
"server '%s' when no response was expected",
mxs_mysql_get_command(buffer), dcb->server->unique_name);
ss_dassert(false);
}
}
/**
* @brief Client Reply routine
*
@ -1102,9 +1136,18 @@ static void clientReply(MXS_ROUTER *instance,
SRWBackend backend = get_backend_from_dcb(rses, backend_dcb);
if (backend->get_reply_state() == REPLY_STATE_DONE)
{
/** If we receive an unexpected response from the server, the internal
* logic cannot handle this situation. Routing the reply straight to
* the client should be the safest thing to do at this point. */
log_unexpected_response(backend_dcb, writebuf);
MXS_SESSION_ROUTE_REPLY(backend_dcb->session, writebuf);
return;
}
/** Statement was successfully executed, free the stored statement */
session_clear_stmt(backend_dcb->session);
ss_dassert(backend->get_reply_state() != REPLY_STATE_DONE);
if (reply_is_complete(backend, writebuf))
{