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MXS-1847: Fix server_get_parameter

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The function now takes an output buffer as a parameter. This prevents race
conditions by copying the parameter value into a local buffer.
This commit is contained in:
Markus Mäkelä
2018-05-02 22:21:18 +03:00
parent e311b86800
commit 612b4e1a32
5 changed files with 43 additions and 29 deletions
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2
include/maxscale/server.h
View File

@ -348,7 +348,7 @@ extern void server_set_status_nolock(SERVER *server, uint64_t bit);
extern void server_clear_status_nolock(SERVER *server, uint64_t bit);
extern void server_transfer_status(SERVER *dest_server, const SERVER *source_server);
extern void server_add_mon_user(SERVER *server, const char *user, const char *passwd);
extern const char *server_get_parameter(const SERVER *server, const char *name);
extern bool server_get_parameter(const SERVER *server, const char *name, char* out, size_t size);
extern void server_update_credentials(SERVER *server, const char *user, const char *passwd);
extern DCB* server_get_persistent(SERVER *server, const char *user, const char* ip, const char *protocol, int id);
extern void server_update_address(SERVER *server, const char *address);

25
server/core/server.cc
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@ -924,24 +924,35 @@ static void server_parameter_free(SERVER_PARAM *tofree)
/**
* Retrieve a parameter value from a server
*
* @param server The server we are looking for a parameter of
* @param name The name of the parameter we require
* @return The parameter value or NULL if not found
* @param server The server we are looking for a parameter of
* @param name The name of the parameter we require
* @param out Buffer where value is stored, use NULL to check if the parameter exists
* @param size Size of @c out, ignored if @c out is NULL
*
* @return True if parameter was found
*/
const char *
server_get_parameter(const SERVER *server, const char *name)
bool server_get_parameter(const SERVER *server, const char *name, char* out, size_t size)
{
bool found = false;
SERVER_PARAM *param = server->parameters;
spinlock_acquire(&server->lock);
while (param)
{
if (strcmp(param->name, name) == 0 && param->active)
{
return param->value;
if (out)
{
snprintf(out, size, "%s", param->value);
}
found = true;
break;
}
param = param->next;
}
return NULL;
spinlock_release(&server->lock);
return found;
}
/**

12
server/core/service.cc
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@ -2253,6 +2253,7 @@ static void service_calculate_weights(SERVICE *service)
if (*weightby && service->dbref)
{
char buf[50]; // Enough to hold most numbers
/** Service has a weighting parameter and at least one server */
int total = 0;
@ -2260,10 +2261,10 @@ static void service_calculate_weights(SERVICE *service)
for (SERVER_REF *server = service->dbref; server; server = server->next)
{
server->weight = SERVICE_BASE_SERVER_WEIGHT;
const char *param = server_get_parameter(server->server, weightby);
if (param)
if (server_get_parameter(server->server, weightby, buf, sizeof(buf)))
{
total += atoi(param);
total += atoi(buf);
}
}
@ -2284,10 +2285,9 @@ static void service_calculate_weights(SERVICE *service)
/** Calculate the relative weight of the servers */
for (SERVER_REF *server = service->dbref; server; server = server->next)
{
const char *param = server_get_parameter(server->server, weightby);
if (param)
if (server_get_parameter(server->server, weightby, buf, sizeof(buf)))
{
int wght = atoi(param);
int wght = atoi(buf);
int perc = (wght * SERVICE_BASE_SERVER_WEIGHT) / total;
if (perc == 0)

7
server/core/test/test_server.cc
View File

@ -63,12 +63,13 @@ test1()
//ss_info_dassert(NULL != service, "New server with valid protocol and port must not be null");
//ss_info_dassert(0 != service_isvalid(service), "Service must be valid after creation");
char buf[120];
ss_dfprintf(stderr, "\t..done\nTest Parameter for Server.");
ss_info_dassert(NULL == server_get_parameter(server, (char*)"name"), "Parameter should be null when not set");
ss_info_dassert(!server_get_parameter(server, "name", buf, sizeof(buf)), "Parameter should be null when not set");
server_add_parameter(server, "name", "value");
mxs_log_flush_sync();
ss_info_dassert(0 == strcmp("value", server_get_parameter(server, (char*)"name")),
"Parameter should be returned correctly");
ss_dassert(server_get_parameter(server, "name", buf, sizeof(buf)));
ss_info_dassert(strcmp("value", buf) == 0, "Parameter should be returned correctly");
ss_dfprintf(stderr, "\t..done\nTesting Unique Name for Server.");
ss_info_dassert(NULL == server_find_by_unique_name("non-existent"),
"Should not find non-existent unique name.");

26
server/modules/monitor/galeramon/galeramon.c
View File

@ -687,7 +687,6 @@ static MXS_MONITORED_SERVER *get_candidate_master(MXS_MONITOR* mon)
long min_id = -1;
int minval = INT_MAX;
int currval;
const char* value;
/* set min_id to the lowest value of moitor_servers->server->node_id */
while (moitor_servers)
{
@ -695,11 +694,11 @@ static MXS_MONITORED_SERVER *get_candidate_master(MXS_MONITOR* mon)
{
moitor_servers->server->depth = 0;
if (handle->use_priority && (value = server_get_parameter(moitor_servers->server, "priority")) != NULL)
char buf[50]; // Enough to hold most numbers
if (handle->use_priority && server_get_parameter(moitor_servers->server, "priority", buf, sizeof(buf)))
{
/** The server has a priority */
if ((currval = atoi(value)) > 0)
if ((currval = atoi(buf)) > 0)
{
/** The priority is valid */
if (currval < minval && currval > 0)
@ -712,7 +711,8 @@ static MXS_MONITORED_SERVER *get_candidate_master(MXS_MONITOR* mon)
else if (moitor_servers->server->node_id >= 0 &&
(!handle->use_priority || /** Server priority disabled*/
candidate_master == NULL || /** No candidate chosen */
server_get_parameter(candidate_master->server, "priority") == NULL)) /** Candidate has no priority */
/** Candidate has no priority */
!server_get_parameter(moitor_servers->server, "priority", buf, sizeof(buf))))
{
if (min_id < 0 || moitor_servers->server->node_id < min_id)
{
@ -846,8 +846,9 @@ static void update_sst_donor_nodes(MXS_MONITOR *mon, int is_cluster)
* If no server has "priority" set, then
* the server list will be order by default method.
*/
if (handle->use_priority &&
server_get_parameter(ptr->server, "priority"))
server_get_parameter(ptr->server, "priority", NULL, 0))
{
ignore_priority = false;
}
@ -980,28 +981,29 @@ static int compare_node_priority (const void *a, const void *b)
{
const MXS_MONITORED_SERVER *s_a = *(MXS_MONITORED_SERVER * const *)a;
const MXS_MONITORED_SERVER *s_b = *(MXS_MONITORED_SERVER * const *)b;
const char *pri_a = server_get_parameter(s_a->server, "priority");
const char *pri_b = server_get_parameter(s_b->server, "priority");
char pri_a[50];
char pri_b[50];
bool have_a = server_get_parameter(s_a->server, "priority", pri_a, sizeof(pri_a));
bool have_b = server_get_parameter(s_b->server, "priority", pri_b, sizeof(pri_b));
/**
* Check priority parameter:
*
* Return a - b in case of issues
*/
if (!pri_a && pri_b)
if (!have_a && have_b)
{
MXS_DEBUG("Server %s has no given priority. It will be at the beginning of the list",
s_a->server->unique_name);
return -(INT_MAX - 1);
}
else if (pri_a && !pri_b)
else if (have_a && !have_b)
{
MXS_DEBUG("Server %s has no given priority. It will be at the beginning of the list",
s_b->server->unique_name);
return INT_MAX - 1;
}
else if (!pri_a && !pri_b)
else if (!have_a && !have_b)
{
MXS_DEBUG("Servers %s and %s have no given priority. They be at the beginning of the list",
s_a->server->unique_name,