arm板作为tcp客户端无法连接网络摄像头，报错误代码111

Question

1.问题背景
需要将arm用网线连接网络摄像头对其进行控制。厂商只提供了CGI接口，且由于系统是裁剪过的curl这些也用不了，所以尝试使用tcp协议直接封装成http。

2.问题现象
用tcp工具，pc作为客户端连接摄像头，发送可以直接接收到有效返回。但是arm板与tcp测试工具或者摄像头都连不上，报111

客户端代码如下

static protocol_err_t protocol_CameraCommand(PROTOCOL *this)
{
    unsigned short port = 8000;           // 服务器的端口号
    char *server_ip = "192.168.13.11";  // 服务器ip地址

    int sockfd = socket(AF_INET, SOCK_STREAM, 0);// 创建TCP套接字
    if(sockfd < 0)
    {
        protocol_SendString(this,"socket failed\n");
        return PROTOCOL_ERR_FAIL;
    }

    struct sockaddr_in server_addr; //定义服务器信息结构体
    bzero(&server_addr,sizeof(server_addr)); 
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port);
    inet_pton(AF_INET, server_ip, &server_addr.sin_addr);

    int err_log = connect(sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr));   // 主动连接服务器
    if(err_log != 0)
    {
        sprintf(this->sendBuffer, "connect error: %s(errno: %d)\n",strerror(errno),errno);
        protocol_SendString(this, this->sendBuffer);
        close(sockfd);
        return PROTOCOL_ERR_FAIL;
    }

    char str1[1024] = "";
    sprintf(str1, "%s\r\n","GET /cgi-bin/date_cgi?action=get&user=admin&pwd=admin HTTP/1.1"); //服务端接收数据处理文件地址,并带参数
    sprintf(str1, "%s%s\r\n",str1,"Accept: text/html, application/xhtml+xml, image/jxr, */*");
    sprintf(str1, "%s%s\r\n",str1,"Accept-Language: zh-CN");
    sprintf(str1, "%s%s\r\n",str1,"User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko");
    sprintf(str1, "%s%s\r\n",str1,"Accept-Encoding: gzip, deflate");
    sprintf(str1, "%s%s\r\n",str1,"Host: 192.168.13.11"); //服务器地址
    sprintf(str1, "%s%s\r\n",str1,"Connection: Keep-Alive");
    //sprintf(str1,"%s%s\r\n",str1,"Cookie: JSESSIONID=5386A9443729D7EB0B61E38A9C7CF52F");
    sprintf(str1, "%s\r\n",str1);   
    protocol_SendString(this,"----------------------------- HTTP Data ----------------------------------\n");
    sprintf(this->sendBuffer,"%s",str1);
    protocol_SendString(this, this->sendBuffer);
    sprintf(this->sendBuffer,"--------------------------- Data Len=%d ----------------------------------\n\n",strlen(str1));
    protocol_SendString(this, this->sendBuffer);

    int ret=send(sockfd, str1, strlen(str1), 0);   // 向服务器发送信息
    if(ret<0)
    {
        protocol_SendString(this,"send");
        close(sockfd);
        return PROTOCOL_ERR_FAIL;
    }

    char recv_buf[521]="";
    recv(sockfd, recv_buf, sizeof(recv_buf), 0);
    protocol_SendString(this, "------------------------ server retrun data -------------------------------\n");
    sprintf(this->sendBuffer,"%s\n\n",recv_buf);
    protocol_SendString(this, this->sendBuffer);
    close(sockfd);

    return PROTOCOL_ERR_NONE;
}

Answer 1

排查网络线路问题：
ping是否正常

排查TCP服务端IP端口问题：
用wget nc telnet 等其他网络工具，测试IP端口是否能通

排查防火墙问题：
关闭服务端这边的防火墙，测试IP端口能不能通

排查代码问题：
在PC或虚拟机上编译运行程序，看是否能能通