RT-Thread-通过socket通信电脑端python和单片机（探索者）RT-Thread问答社区

通过socket通信电脑端python和单片机（探索者）

发布于 2023-10-30 16:40:49 浏览：442 订阅该版

```c
lwIP-2.1.2 initialized!
[32m[I/sal.skt] Socket Abstraction Layer initialize success.[0m
socket bind network interface device(e0) success!
socket connect failed!
```
串口调试助手出现以上问题

主代码如下：

```c
    struct sockaddr_in client_addr;
    struct sockaddr_in server_addr;
    struct netdev *netdev = RT_NULL;
    int sockfd = -1;

if (argc != 2)
    {
        rt_kprintf("bind_test [netdev_name]  --bind network interface device by name.\n");
        return -RT_ERROR;
    }

/* 通过名称获取 netdev 网卡对象 */
    netdev = netdev_get_by_family(AF_INET);
    if (netdev == RT_NULL)
    {
        rt_kprintf("get network interface device(%s) failed.\n");
        return -RT_ERROR;
    }

if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        rt_kprintf("Socket create failed.\n");
        return -RT_ERROR;
    }

/* 初始化需要绑定的客户端地址 */
    client_addr.sin_family = AF_INET;
    client_addr.sin_port = htons(8080);
    /* 获取网卡对象中 IP 地址信息 */
    client_addr.sin_addr.s_addr = netdev->ip_addr.addr;
    rt_memset(&(client_addr.sin_zero), 0, sizeof(client_addr.sin_zero));

if (bind(sockfd, (struct sockaddr *)&client_addr, sizeof(struct sockaddr)) < 0)
    {
        rt_kprintf("socket bind failed.\n");
        closesocket(sockfd);
        return -RT_ERROR;
    }
    rt_kprintf("socket bind network interface device(%s) success!\n", netdev->name);

/* 初始化预连接的服务端地址 */
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT);
    server_addr.sin_addr.s_addr = inet_addr(SERVER_HOST);
    rt_memset(&(server_addr.sin_zero), 0, sizeof(server_addr.sin_zero));

/* 连接到服务端 */
    if (connect(sockfd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)) < 0)
    {
        rt_kprintf("socket connect failed!\n");
        closesocket(sockfd);
        return -RT_ERROR;
    }
    else
    {
        rt_kprintf("socket connect success!\n");
    }

/* 关闭连接 */
    closesocket(sockfd);
    return RT_EOK;
	
```
经过调试 发现是在连接到服务端的时候出错了：

```c
int lwip_connect(int s, const struct sockaddr *name, socklen_t namelen)
{
  struct lwip_sock *sock;
  err_t err;

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

if (!SOCK_ADDR_TYPE_MATCH_OR_UNSPEC(name, sock)) {
    /* sockaddr does not match socket type (IPv4/IPv6) */
    sock_set_errno(sock, err_to_errno(ERR_VAL));
    done_socket(sock);
    return -1;
  }

LWIP_UNUSED_ARG(namelen);
  if (name->sa_family == AF_UNSPEC) {
    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, AF_UNSPEC)\n", s));
    err = netconn_disconnect(sock->conn);
  } else {
    ip_addr_t remote_addr;
    u16_t remote_port;

/* check size, family and alignment of 'name' */
    LWIP_ERROR("lwip_connect: invalid address", IS_SOCK_ADDR_LEN_VALID(namelen) &&
               IS_SOCK_ADDR_TYPE_VALID_OR_UNSPEC(name) && IS_SOCK_ADDR_ALIGNED(name),
               sock_set_errno(sock, err_to_errno(ERR_ARG)); done_socket(sock); return -1;);

SOCKADDR_TO_IPADDR_PORT(name, &remote_addr, remote_port);
    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, addr=", s));
    ip_addr_debug_print_val(SOCKETS_DEBUG, remote_addr);
    LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F")\n", remote_port));

#if LWIP_IPV4 && LWIP_IPV6
    /* Dual-stack: Unmap IPv4 mapped IPv6 addresses */
    if (IP_IS_V6_VAL(remote_addr) && ip6_addr_isipv4mappedipv6(ip_2_ip6(&remote_addr))) {
      unmap_ipv4_mapped_ipv6(ip_2_ip4(&remote_addr), ip_2_ip6(&remote_addr));
      IP_SET_TYPE_VAL(remote_addr, IPADDR_TYPE_V4);
    }
#endif /* LWIP_IPV4 && LWIP_IPV6 */

err = netconn_connect(sock->conn, &remote_addr, remote_port);
  }

if (err != ERR_OK) {
    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d) failed, err=%d\n", s, err));
    sock_set_errno(sock, err_to_errno(err));
    done_socket(sock);
    return -1;
  }

LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d) succeeded\n", s));
  sock_set_errno(sock, 0);
  done_socket(sock);
  return 0;
}
```

程序进入以上函数之后
  
```c
LWIP_UNUSED_ARG(namelen);
  if (name->sa_family == AF_UNSPEC) {
    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, AF_UNSPEC)\n", s));
    err = netconn_disconnect(sock->conn);
  } else
```
  在这个if处进入了else
  
 
```c
 lwIP-2.1.2 initialized!
[32m[I/sal.skt] Socket Abstraction Layer initialize success.[0m
socket bind network interface device(e0) success!
socket connect failed!
msh />ifconfig
network interface device: e0 (Default)
MTU: 1500
MAC: 00 80 e1 11 4b 4f 
FLAGS: UP LINK_UP INTERNET_DOWN DHCP_DISABLE ETHARP BROADCAST IGMP
ip address: 192.168.1.30
gw address: 192.168.1.1
net mask  : 255.255.255.0
dns server #0: 0.0.0.0
dns server #1: 0.0.0.0
msh />
msh />ping 192.168.1.100
60 bytes from 192.168.1.100 icmp_seq=0 ttl=128 time=3 ms
60 bytes from 192.168.1.100 icmp_seq=1 ttl=128 time=1 ms
60 bytes from 192.168.1.100 icmp_seq=2 ttl=128 time=1 ms
60 bytes from 192.168.1.100 icmp_seq=3 ttl=128 time=1 ms
msh />
msh />
```

可以ping通 但是就是没法建立连接