Question

我有一个特定的设备（IP：192.168.0.10端口3000 - 它是一个信号接收器），必须通过UDP控制。我应该能够发送这个设备基本命令，例如'reset'; 'log'; '跑'......

经过一番努力和stackoverflow的温和帮助后，我设法使用netcat与我的设备进行通信。它现在完美无缺。更改计算机eth IP后，我使用了命令 nc -u 192.168.0.10 3000 。（我在linux下）。

现在，这就是目标，我需要和netcat一样，但是，使用C语言。由于我是初学者，我尝试使用互联网并写下：

    /* Standard Linux headers */
    #include <stdio.h> //printf
    #include <string.h> //memset
    #include <stdlib.h> //exit(0);
    #include <arpa/inet.h>
    #include <sys/socket.h>
    #include <sys/types.h>
    #include <errno.h>


/* DEFINE */ 
#define SERVER "192.168.0.10"
#define BUFFLEN 1024  //Max length of buffer
#define PORT 3000   //The port on which to send data


int main (void)
{

/*
   **  Definition of the local variables.
*/
  struct sockaddr_in serv_addr; /* Server Socket address structure*/
 /* short int status = 0; /* internal status return*/
 /*  unsigned short int return_status = 0; /* the returnes status value */

  char recepbuff[BUFFLEN];
  char cmd[BUFFLEN];
  int socket_fd;

/* 
    **  Initialisation of the local variables.
*/
 memset(recepbuff, '0' ,sizeof(recepbuff)); /*pareil que bzero*/


/*
   **  Creating the socket
   **  call socket (it creates an endpoint for communication and
   **                returns the socket descriptor.
   **                 To create an UDP socket here are the param
   **                 The protocol family should be AF_INET
   **                 The protocol type is SOCK_DGRAM
   **                 The protocol should beset to default ie
   **                 DEF_PROTOCOL wich is default so 0. );
*/

if ( (socket_fd = socket(AF_INET, SOCK_DGRAM, 0) ) < 0 ) /* return 1 if okay */
  {
    printf("ERROR opening socket");
  }

  serv_addr.sin_family = AF_INET; /*Define the domain used*/
  serv_addr.sin_port = htons(PORT); /*Declare port #PORT to be used*/
  /*serv_addr.sin_addr.s_addr = inet_addr("127.0.0.1"); /*Permit any incoming IP address by declaring INADDR_ANY*/

// Convert IPv4 and IPv6 addresses from text to binary form
if(inet_pton(AF_INET, SERVER, &serv_addr.sin_addr)<=0) 
  {
    printf("\nInvalid address/ Address not supported \n");
    return -1;
  }

if (connect(socket_fd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
  {
    printf("\nConnection Failed \n");
    return -1;
 }
else
{
    printf("\n Connected \n");
}

/* Messaging*/   
  while(1)
    {
        printf("Enter command : ");
        gets(cmd);

        //send the message
        if ( (sendto(socket_fd , cmd , strlen(cmd) , 0 , (struct sockaddr *)&serv_addr, sizeof(serv_addr)) ) < 0 )
        {

          printf("DEBUG_CMD: Failed sending cmd\n");
        }
        else
        {
            printf("DEBUG_CMD : CMD * %s * SENT\n", cmd);
            puts(cmd);
        }

        //receive a reply and print it
        //clear the buffer by filling null, it might have previously received data
        memset(recepbuff, '0' ,sizeof(recepbuff));
        printf("mini-debug memset done\n");

        //try to receive some data, this is a blocking call
        if ((recvfrom( socket_fd, recepbuff, strlen(recepbuff), 0, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) ) < 0)
        {

          printf("DEBUG_RECEP: Failed received cmd\n");
        }
        else

        {
            printf("DEBUG_RECEP : CMD RECEIVED\n");
        }
         puts(recepbuff);
    }

close(socket_fd);
return 0;

}

所以，我启动我的程序，它似乎正确连接。我输入我的命令，一个简单的重置然后没有任何反应。就像它在 recvfrom 处被阻止一样（因为打印了“mini debug memset done”）。而且我找不到任何关于我做错的线索。

编辑：修正了recvfrom =＆gt;中的strlen一样事实上，我甚至不确定我是否正在使用正确的方法，即使我真的“联系”......

UDP连接 - C中的套接字编程

0 个答案: