Thread: Help with server Socket Chat code

hey guys, writing code server recognize multiple clients. far getting error "segmentation fault" when run code. believe line of code:

code:

for(p = ai; p != null; p = p->ai_next){

i made modification original code taken off site. assume way wrote may conflict how code runs.


thank time

note: not homework/project assignment. want understanding of socket programming.

code:

/* simple server in internet domain using tcp     port number passed argument */  #include <stdio.h>  #include <stdlib.h>  #include <string.h>  #include <unistd.h>  #include <sys/types.h>   #include <sys/socket.h>  #include <netinet/in.h>    #include <arpa/inet.h>  #include <netdb.h>    void error(const char *msg)  {      perror(msg);      exit(1);  }    int main(int argc, char *argv[])  {       fd_set master;    // master file descriptor list       fd_set read_fds;  // temp file descriptor list select()       int fdmax;        // maximum file descriptor number         int sockfd, newsockfd, portno;       socklen_t clilen;       char buffer[256];       int yes=1; //for setsockopt       struct sockaddr_in serv_addr, cli_addr;       int i, j, rv;       int nbytes;       char remoteip[inet6_addrstrlen];       struct addrinfo hints, *ai, *p;       fd_zero(&master);    // clear master , temp sets       fd_zero(&read_fds);         if (argc < 2) {           fprintf(stderr,"error, no port provided\n");           exit(1);       }         bzero((char *) &serv_addr, sizeof(serv_addr));       portno = atoi(argv[1]);       serv_addr.sin_family = af_inet;       serv_addr.sin_addr.s_addr = inaddr_any;       serv_addr.sin_port = htons(portno);         for(p = ai; p != null; p = p->ai_next){           sockfd = socket(af_inet, sock_stream, 0);           if (sockfd < 0){  	     continue;           }  	//printf("the value sockfd %d \n", sockfd);       //if (sockfd < 0)          // error("error opening socket");         	 if (setsockopt(sockfd,sol_socket,so_reuseaddr,                &yes,sizeof(int)) == -1) {      	      error("setsockopt");      	      exit(1);       	 }  	      	 if (bind(sockfd, (struct sockaddr *) &serv_addr,               sizeof(serv_addr)) < 0){                close(sockfd);  	     continue;           }  	     break;       }           if (listen(sockfd,5) == -1)       {           error("error on listen");  	 exit(3);       }        // add sockfd master set      fd_set(sockfd, &master);      // keep track of biggest file descriptor      fdmax = sockfd; // far, it's 1      // main loop      for(;;) {          read_fds = master; // copy          if (select(fdmax+1, &read_fds, null, null, null) == -1) {              perror("select");              exit(4);          }  //printf("we @ before main loop");      for(i = 0; <= fdmax; i++) {          if (fd_isset(i, &read_fds)) { // got one!!              if (i == sockfd) {                  // handle new connections         		clilen = sizeof(cli_addr);      		 newsockfd = accept(sockfd,                    (struct sockaddr *) &cli_addr,                    &clilen);         		if (newsockfd < 0)             	    error("error on accept");  			else {                          fd_set(newsockfd, &master); // add master set                          if (newsockfd > fdmax) {    // keep track of max                              fdmax = newsockfd;                          }                          printf("selectserver: new connection %s on "                              "socket %d\n",                              inet_ntop(af_inet,                                  &(serv_addr.sin_addr),                                  remoteip, inet6_addrstrlen),                              newsockfd);                      }                  } else {                      // handle data client                      if ((nbytes = recv(i, buffer, sizeof buffer, 0)) <= 0) {                          // got error or connection closed client                          if (nbytes == 0) {                              // connection closed     			printf("selectserver: socket %d hung up\n", i);                          } else {                              error("recv");                          }                          close(i); // bye!                          fd_clr(i, &master); // remove master set                      } else {                          // got data client                          for(j = 0; j <= fdmax; j++) {                              // send everyone!                              if (fd_isset(j, &master)) {                                  // except sockfd , ourselves                                  if (j != sockfd && j != i) {                                      if (send(j, buffer, nbytes, 0) == -1) {                                          error("send");                                      }                                  }                              }                          }                      }                  } // end handle data client              } // end got new incoming connection          } // end looping through file descriptors      } // end for(;;)--and thought never end!            return 0;    }//end of main

i can see declare ai , p variable pointer struct addrinfo. can't find spot initialize them. uninitialized pointers point problems.

first make them point usefull use them.

cheers.

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