@echo off

:: Config your interval time (seconds)
set disable_interval_time=5
set enable_interval_time=15

:: Config your loop times: enable->disable->enable->disable...
set loop_time=10000

:: Config your network adapter list
SET adapter_num=1
SET adapter[0].name=WLAN
::SET adapter[0].name=屑薪鈺犘も晲协
::SET adapter[1].name=屑薪鈺犘も晲协 2

:::::::::::::::::::::::::::::::::::::::::::::::::::::::

echo Loop to switch network adapter state with interval time %interval_time% seconds

set loop_index=0

:LoopStart

if %loop_index% EQU %loop_time% goto :LoopStop

:: Set enable or disable operation
set /A cnt=%loop_index% + 1
set /A result=cnt%%2
if %result% equ 0 (
set operation=enabled
set interval_time=%enable_interval_time%
) else (
set operation=disable
set interval_time=%disable_interval_time%
)
echo [%date:~0,10% %time:~0,2%:%time:~3,2%:%time:~6,2%] loop time ... %cnt% ... %operation%

set adapter_index=0
:AdapterStart
if %adapter_index% EQU %adapter_num% goto :AdapterStop
set adapter_cur.name=0

for /F "usebackq delims==. tokens=1-3" %%I in (`set adapter[%adapter_index%]`) do (
	set adapter_cur.%%J=%%K
)

:: swtich adapter state
call:adapter_switch "%adapter_cur.name%" %operation%

set /A adapter_index=%adapter_index% + 1

goto AdapterStart

:AdapterStop

set /A loop_index=%loop_index% + 1

echo [%date:~0,10% %time:~0,2%:%time:~3,2%:%time:~6,2%] sleep some time (%interval_time% seconds) ...
ping -n %interval_time% 127.0.0.1 > nul

goto LoopStart

:LoopStop

echo End of loop ...

pause
goto:eof

:: function definition
:adapter_switch
set cmd=netsh interface set interface %1 %2
echo %cmd%
%cmd%
goto:eof

# ping www.baidu.com
ping_Command
ping IP address:www.baidu.com
ping: create socket failed

# ping www.baidu.com
ping_Command
ping IP address:www.baidu.com
60 bytes from 14.215.177.39 icmp_seq=0 ttl=53 time=40 ticks
60 bytes from 14.215.177.39 icmp_seq=1 ttl=53 time=118 ticks
60 bytes from 14.215.177.39 icmp_seq=2 ttl=53 time=68 ticks
60 bytes from 14.215.177.39 icmp_seq=3 ttl=53 time=56 ticks

/**
 * Allocate a new socket for a given netconn.
 *
 * @param newconn the netconn for which to allocate a socket
 * @param accepted 1 if socket has been created by accept(),
 *                 0 if socket has been created by socket()
 * @return the index of the new socket; -1 on error
 */
static int
alloc_socket(struct netconn *newconn, int accepted)
{
  int i;
  SYS_ARCH_DECL_PROTECT(lev);

  /* allocate a new socket identifier */
  for (i = 0; i < NUM_SOCKETS; ++i) {
    /* Protect socket array */
    SYS_ARCH_PROTECT(lev);
    if (!sockets[i].conn && (sockets[i].select_waiting == 0)) {
      sockets[i].conn       = newconn;
      /* The socket is not yet known to anyone, so no need to protect
         after having marked it as used. */
      SYS_ARCH_UNPROTECT(lev);
      sockets[i].lastdata   = NULL;
      sockets[i].lastoffset = 0;
      sockets[i].rcvevent   = 0;
      /* TCP sendbuf is empty, but the socket is not yet writable until connected
       * (unless it has been created by accept()). */
      sockets[i].sendevent  = (NETCONNTYPE_GROUP(newconn->type) == NETCONN_TCP ? (accepted != 0) : 1);
      sockets[i].errevent   = 0;
      sockets[i].err        = 0;
	  SOC_INIT_SYNC(&sockets[i]);
      return i + LWIP_SOCKET_OFFSET;
    }
    SYS_ARCH_UNPROTECT(lev);
  }
  return -1;
}

宏定义替换
#define NUM_SOCKETS MEMP_NUM_NETCONN

在lwipopts.h中找到了其最终的替换
/**
 * MEMP_NUM_NETCONN: the number of struct netconns.
 * (only needed if you use the sequential API, like api_lib.c)
 *
 * This number corresponds to the maximum number of active sockets at any
 * given point in time. This number must be sum of max. TCP sockets, max. TCP
 * sockets used for listening, and max. number of UDP sockets
 */
#define MEMP_NUM_NETCONN	(MAX_SOCKETS_TCP + \\
	MAX_LISTENING_SOCKETS_TCP + MAX_SOCKETS_UDP)

int
lwip_close(int s)
{
  struct lwip_sock *sock;
  int is_tcp = 0;
  err_t err;

  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_close(%d)\\n", s));

  sock = get_socket(s);
  if (!sock) {
    return -1;
  }
  SOCK_DEINIT_SYNC(1, sock);

  if (sock->conn != NULL) {
    is_tcp = NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP;
  } else {
    LWIP_ASSERT("sock->lastdata == NULL", sock->lastdata == NULL);
  }

#if LWIP_IGMP
  /* drop all possibly joined IGMP memberships */
  lwip_socket_drop_registered_memberships(s);
#endif /* LWIP_IGMP */

  err = netconn_delete(sock->conn);
  if (err != ERR_OK) {
    sock_set_errno(sock, err_to_errno(err));
    return -1;
  }

  free_socket(sock, is_tcp);
  set_errno(0);
  return 0;
}

/** Free a socket. The socket's netconn must have been
 * delete before!
 *
 * @param sock the socket to free
 * @param is_tcp != 0 for TCP sockets, used to free lastdata
 */
static void
free_socket(struct lwip_sock *sock, int is_tcp)
{
  void *lastdata;

  lastdata         = sock->lastdata;
  sock->lastdata   = NULL;
  sock->lastoffset = 0;
  sock->err        = 0;

  /* Protect socket array */
  SYS_ARCH_SET(sock->conn, NULL);
  /* don't use 'sock' after this line, as another task might have allocated it */

  if (lastdata != NULL) {
    if (is_tcp) {
      pbuf_free((struct pbuf *)lastdata);
    } else {
      netbuf_delete((struct netbuf *)lastdata);
    }
  }
}

if (!sockets[i].conn && (sockets[i].select_waiting == 0)) {
      //分配新的句柄编号
      sockets[i].conn       = newconn;
      。。。
}

#define SOC_INIT_SYNC(sock) do { something ... } while(0)
#define SOC_DEINIT_SYNC(sock) do { SOCK_CHECK_NOT_CLOSING(sock); something ... } while(0)
#define SOCK_CHECK_NOT_CLOSING(sock) do { \\
		if ((sock)->closing) { \\
			SOCK_DEBUG(1, "SOCK_CHECK_NOT_CLOSING:[%d]\\n", (sock)->closing); \\
			return -1; \\
		} \\
	} while (0)

/*
 * Gracefully close the connection
 */
void mbedtls_net_free( mbedtls_net_context *ctx )
{
    if( ctx->fd == -1 )
        return;

    shutdown( ctx->fd, 2 );
    close( ctx->fd );

    ctx->fd = -1;
}