#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <error.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>

#define errExit(msg)    do { perror(msg); _exit(EXIT_FAILURE); } while (0)

#define SOCK_PATH  "/tmp/unix_sock.server"
#define DATA "Hello from server"
#define BUF 128
#define FIN "exit"

int session(int client_sock, struct sockaddr_un server_sockaddr, struct sockaddr_un client_sockaddr){     
 int rc;
 char inbuf[BUF];
 char outbuf[BUF];
 int bytes_rec = 0;
 size_t bs = BUF;
 socklen_t len;
   len = sizeof(client_sockaddr);
   rc = getpeername(client_sock, (struct sockaddr *) &client_sockaddr, &len);
   if (rc == -1){
      close(client_sock);
      errExit("getpeer");
   } else {
      printf("Client socket filepath: %s\n", client_sockaddr.sun_path);
   }
    
   printf("waiting to read...\n");
   memset(inbuf, 0, bs);                
   bytes_rec = recv(client_sock, inbuf, bs, 0);
   if (bytes_rec == -1){
      close(client_sock);
      errExit("recv");
   } else {
      printf("DATA RECEIVED = %s\n", inbuf);
   }
    
   memset(outbuf, 0, bs);
   strcpy(outbuf, DATA);      
   printf("Sending data...\n");
   rc = send(client_sock, outbuf, strlen(outbuf), 0);
   if (rc == -1) {
      close(client_sock);
      errExit("send");
   } else {
      printf("Data sent!\n");
   }
   close(client_sock);
   return strcmp(inbuf,FIN);
}


int main(void){

 int server_sock, client_sock, rc;
 socklen_t len;
 struct sockaddr_un server_sockaddr;
 struct sockaddr_un client_sockaddr;     
 int backlog = 10;

 len = sizeof(server_sockaddr);
 memset(&server_sockaddr, 0, sizeof(struct sockaddr_un));
 memset(&client_sockaddr, 0, sizeof(struct sockaddr_un));
    
 server_sock = socket(AF_UNIX, SOCK_STREAM, 0);
 if (server_sock == -1) errExit("socket");
    
 server_sockaddr.sun_family = AF_UNIX;   
 strcpy(server_sockaddr.sun_path, SOCK_PATH); 
    
 unlink(SOCK_PATH);
 rc = bind(server_sock, (struct sockaddr *) &server_sockaddr, len);
 if (rc == -1){
    close(server_sock);
    errExit("bind");
 }
    
 rc = listen(server_sock, backlog);
 if (rc == -1){
    close(server_sock);
    errExit("listen");
 }

 printf("socket listening...\n");

 do {
   client_sock = accept(server_sock, (struct sockaddr *) &client_sockaddr, &len);
   if (client_sock == -1){
      close(server_sock);
      close(client_sock);
      errExit("accept");
   }
 } while (session(client_sock,server_sockaddr,client_sockaddr));
   

 close(server_sock);
 unlink(SOCK_PATH);
    
 return 0;
}