二、源码跟踪
在Connection Manager中提到了login_connection函数用于检查用户名和密码等相关信息，其源码如下（重点的函数代码
会着色）：
static bool login_connection(THD *thd)
{
NET *net= &thd->net;
int error;
DBUG_ENTER("login_connection");
DBUG_PRINT("info", ("login_connection called by thread %lu",
thd->thread_id));
/* Use "connect_timeout" value during connection phase */
my_net_set_read_timeout(net, connect_timeout);
my_net_set_write_timeout(net, connect_timeout);
error= check_connection(thd); //此处是验证的具体函数
net_end_statement(thd);
if (error)
{ // Wrong permissions
#ifdef __NT__
if (vio_type(net->vio) == VIO_TYPE_NAMEDPIPE)
my_sleep(1000); /* must wait after eof() */
#endif
statistic_increment(aborted_connects,&LOCK_status);
DBUG_RETURN(1);
}
/* Connect completed, set read/write timeouts back to default */
my_net_set_read_timeout(net, thd->variables.net_read_timeout);
my_net_set_write_timeout(net, thd->variables.net_write_timeout);
DBUG_RETURN(0);
}
此函数主要是功能是调用函数check_connection进行用户认证,由于函数check_connection过长，对其进行简化，如下所示：
static int check_connection(THD *thd)
{
uint connect_errors= 0;
NET *net= &thd->net;
ulong pkt_len= 0;
char *end;
DBUG_PRINT("info",
("New connection received on %s", vio_description(net->vio)));
#ifdef SIGNAL_WITH_VIO_CLOSE
thd->set_active_vio(net->vio);
#endif
if (!thd->main_security_ctx.host) // If TCP/IP connection
{
char ip[30];
if (vio_peer_addr(net->vio, ip, &thd->peer_port))
{
my_error(ER_BAD_HOST_ERROR, MYF(0), thd->main_security_ctx.host_or_ip);
return 1;
}
if (!(thd->main_security_ctx.ip= my_strdup(ip,MYF(MY_WME))))
return 1; /* The error is set by my_strdup(). */
thd->main_security_ctx.host_or_ip= thd->main_security_ctx.ip;
vio_in_addr(net->vio,&thd->remote.sin_addr);
if (!(specialflag & SPECIAL_NO_RESOLVE))
{
vio_in_addr(net->vio,&thd->remote.sin_addr);
thd->main_security_ctx.host=
ip_to_hostname(&thd->remote.sin_addr, &connect_errors);
/* Cut very long hostnames to avoid possible overflows */
if (thd->main_security_ctx.host)
{
if (thd->main_security_ctx.host != my_localhost)
thd->main_security_ctx.host[min(strlen(thd->main_security_ctx.host),
HOSTNAME_LENGTH)]= 0;
thd->main_security_ctx.host_or_ip= thd->main_security_ctx.host;
}
if (connect_errors > max_connect_errors)
{
my_error(ER_HOST_IS_BLOCKED, MYF(0), thd->main_security_ctx.host_or_ip);
return 1;
}
}
...
if (acl_check_host(thd->main_security_ctx.host, thd->main_security_ctx.ip))//此处验证主机名或IP是否存在
{
my_error(ER_HOST_NOT_PRIVILEGED, MYF(0),
thd->main_security_ctx.host_or_ip);
return 1;
}
}
else /* Hostname given means that the connection was on a socket */