MySQL: 如何判定连接用的IPV6

---

笔记，仅供参考。

---

MySQL 支持IPV6 连接，但是收到bind_address参数影响，如下：

• 设置 0.0.0.0 为IPV4
• 设置* 为IPV6和VIP4都支持
• 设置 对应IP ，则在对应IP上进行监听
• 设置:: 为IPV6

具体可以查看代码listen 端口的建立方式，查看bind_address是如何生效的。

Linux的net.ipv6.conf.all.disable_ipv6代表是否禁用IPV6协议

[root@pxctest6 ~]# more /etc/sysctl.conf 
# sysctl settings are defined through files in
# /usr/lib/sysctl.d/, /run/sysctl.d/, and /etc/sysctl.d/.
#
# Vendors settings live in /usr/lib/sysctl.d/.
# To override a whole file, create a new file with the same in
# /etc/sysctl.d/ and put new settings there. To override
# only specific settings, add a file with a lexically later
# name in /etc/sysctl.d/ and put new settings there.
#
# For more information, see sysctl.conf(5) and sysctl.d(5).
net.ipv6.conf.all.disable_ipv6=0

• 进行ping测试
  ping6 fe80::20c:29ff:fe7d:9453%ens33

MySQL通过ipv6连接测试和连接协议的判定

[root@pxctest6 ~]# mysql -u mytest -p'gelc1233' -h 'fe80::20c:29ff:fe7d:9453%ens33' -P 3370
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1045 (28000): Access denied for user 'mytest'@'fe80::20c:29ff:fe67:d1bf%ens33' (using password: YES)

连接可以看到报错也是用户+地址

需要注意的是，是否使用ipv6协议是通过mysql客户端进行判断的，根据其输入的IP地址类型进行判定的，主要函数为getaddrinfo，进行判定参考函数csm_begin_connect，host为IP，port_buf为端口，如下：

gai_errno = getaddrinfo(host, port_buf, &hints, &res_lst);
res_lst为一个结果的链表，多种type和协议类型等组合?

• 获取IP的协议类型
• 将访问的地址

等一起封装到res_lst

去掉IPV6支持可以是

• 设置bind_address=0.0.0.0
• 设置net.ipv6.conf.all.disable_ipv6=1，关闭IPV6协议栈支持

另外是否为socket本地连接，两个方式

• 开general log 本地连接为socket连接，否则为tcp。
• 看strace，在check_connect函数里面走的流程不一样，tcp连接需要通过函数getpeername函数获取远端IP。

下面模拟一下MySQL client 判定受用IPV4还是IPV6协议栈时用到的函数getaddrinfo

#include<stdlib.h>
#include<stdio.h>
#include <assert.h>
#include <unistd.h>
#include <signal.h>
#include<netdb.h>

const char* hostv6 = "fe80::20c:29ff:fe7d:9453";
const char* hostv4 = "192.168.1.1";

int main(void)
{
  
  const char *port_buf = "3306";
  struct addrinfo *res_lst, hints;
  struct addrinfo *t_res;
  
  int errno = 0;
  const char* t1 = hostv6;
  const char* t2 = hostv4; 
  printf("AF_INET6 :%d\n",AF_INET6);
  printf("AF_INET  :%d\n",AF_INET);
  printf("SOCK_STREAM :%d\n",SOCK_STREAM);
  printf("SOCK_DGRAM :%d\n",SOCK_DGRAM);
  printf("IPPROTO_IP :%d\n",IPPROTO_IP);
  printf("IPPROTO_TCP %d\n",IPPROTO_TCP);
  printf("IPPROTO_UDP %d\n",IPPROTO_UDP);
  
  
  
  errno = getaddrinfo(t1, port_buf, &hints, &res_lst);
  
  /*
  if(errno != 0)
  {
    perror("err:");
    exit(0);
  
  }
  */
  
  for (t_res = res_lst; t_res; t_res = t_res->ai_next)
  {
   printf("socket, family: %d  type: %d  proto: %d\n",t_res->ai_family, t_res->ai_socktype, t_res->ai_protocol);
  }
  
  errno = getaddrinfo(t2, port_buf, &hints, &res_lst);
 
  /*
  if(errno != 0)
  {
    perror("err:");
    exit(0);
  
  }
  */
  
  for (t_res = res_lst; t_res; t_res = t_res->ai_next)
  {
   printf("socket, family: %d  type: %d  proto: %d\n",t_res->ai_family, t_res->ai_socktype, t_res->ai_protocol);
  }
  return 0;
}


AF_INET6 :10
AF_INET  :2
SOCK_STREAM :1
SOCK_DGRAM :2
IPPROTO_IP :0
IPPROTO_TCP 6
IPPROTO_UDP 17
socket, family: 10  type: 1  proto: 6
socket, family: 10  type: 2  proto: 17
socket, family: 10  type: 3  proto: 0
socket, family: 2  type: 1  proto: 6
socket, family: 2  type: 2  proto: 17
socket, family: 2  type: 3  proto: 0