Error: struct sockaddr_un' has no member named 'sun_port'

Question

I'm getting a few errors trying to make a simple unix socket program. So far, I have the server program working. I'm trying to write a programs that lets the client repeatedly send messages to the server program, and the server will display them. I've got two compiler windows open to test this. I'm getting errors that I assume are related to header files or unix specific stuff. I tried using, "sun_addr" instead of "sin_addr" (for unix), and it didn't work.

Errors...(EDITED FOR AFTER CHANGING ALL TO "UN" AND NOT "IN")

error:'struct sockaddr_un' has no member named 'sun_port'

Code...

   #include <sys/types.h>
   #include <sys/socket.h>
   #include <stdio.h>
   #include <stdlib.h>
   #include <sys/un.h>
   #include <unistd.h>
   #include <string.h>
   #include <arpa/inet.h>

  #define LEN 256
  #define SOCKET_NAME "client_socket"

 int main(void)
 {
   char message[LEN];
   int sock;
   struct sockaddr_un server_socket;
   char server_reply[LEN];

    //create af_unix/socket stream w/call to socket func
    sock = socket(AF_UNIX , SOCK_STREAM , 0);
    if(sock == -1)
      {
       perror("Could not create socket");
      }

   puts("Socket created");

  //errors and warnings here...
   server_socket.sun_family = AF_UNIX;
   server_socket.sun_port = htons( 8888 );//or use sun_path?

  if(connect(sock ,(struct sockaddr *)&server_socket, sizeof(server_socket)) 
                                                                         <0)
    {
     perror("Connect failed.");
     return 1;
    }

    puts("Connected\n");

 while(1)
     {
       printf("Enter message : ");
       scanf("%s" , message);

        //Send some data
        if( send(sock , message , strlen(message) , 0) < 0)
          {
            puts("Send failed");
                        return 1;
          }

        //Receive a reply from the server
        if( recv(sock , server_reply , 2000 , 0) < 0)
          {
           puts("recv failed");
            break;
          }

        puts("Server reply :");
        puts(server_reply);
     }

 close(sock);
 return 0;
}

Looking at the documentation the struct that has sin_family, sin_port and sin_addr is sockaddr_in, as defined in netinet/in.h, which you have not included.*un* is Unix socket, *in* is internet address. — Toby, May 18 '17 at 08:09
@MikhailRomanko I think so. I changed them all to _un because I goofed with "in". New error is... client.c:30:16: error: 'struct sockaddr_un' has no member named 'sun_port' — , May 18 '17 at 08:20
@Toby I see. I just want to use this on my CS labs server, New error is client.c:30:16: error: 'struct sockaddr_un' has no member named 'sun_port' . I'm wondering if I shouldn't use port or the number is wrong. — , May 18 '17 at 08:24
Is there a specific reason why you want to use unix sockets instead of internet sockets? It seems to me that you aren't aware of the differences. — Klas Lindbäck, May 18 '17 at 08:29
@KlasLindbäck I'm using it on my college server and the professor wants unix sockets. I was mixing the two up, as a few people pointed out. — , May 18 '17 at 08:34
@Maddy The address of a unix socket is a path instead of the combination of ip address and port used by internet sockets. The path name is similar (but unrelated) to file path names. Try reading the documentation and look up an example on the internet. — Klas Lindbäck, May 18 '17 at 09:02

score 1 · Accepted Answer · edited May 23 '17 at 12:34

This is the definition of sockaddr_un and it doesn't have any members like sin_family and other that are reported in errors.

  struct sockaddr_un{
                short                    sun_family;                /*AF_UNIX*/
                char                     sun_PATH[108];        /*path name */
   };

The structure you think you are using is this one

struct sockaddr_in {
                short                     sin_family;                   /* AF_INET */
                u_short                   sin_port;                     /* 16-bit port number */
                struct in_addr            sin_addr;
                char                      sin_zero[8];                  /* unused */
   };

struct in_addr {
                u_long                  s_addr;                        /*32-bit net id */
   };

I think you are mixing the processing of families like AF_INET and AF_UNIX. Here is how to write for AF_INET.

#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define PORT 12345

int main()
{
  struct sockaddr_in addr;
  int fd;

  fd = socket(AF_INET, SOCK_STREAM, 0);
  if(fd == -1)
  {
      printf("Error opening socket\n");
      return -1;
  }

  addr.sin_port = htons(PORT);
  addr.sin_addr.s_addr = 0;
  addr.sin_addr.s_addr = INADDR_ANY;
  addr.sin_family = AF_INET;

  if(bind(fd, (struct sockaddr *)&addr,sizeof(struct sockaddr_in) ) == -1)
  {
      printf("Error binding socket\n");
      return -1;
  }

  printf("Successfully bound to port %u\n", PORT);
}

And for AF_UNIX, You can look at this and other related examples Client/Server Socket Communication (AF_UNIX)

Error: struct sockaddr_un' has no member named 'sun_port'

1 Answers1