Thread: select server help

So i wrote a server that incorporates the select function but it is not working properly. I know that I am missing something vital but what? I am trying to make it echo the message from the client back to the client.

This is the output of the client ->

Code:

blah@blah:~/Documents/nix-chat-ui$ ./client 127.0.0.1 12345
Made a connection to 127.0.0.1
Message: hey
server: hey
Message: hey
server: hey
Message: hey
blah@blah:~/Documents/nix-chat-ui$

The client closes after 3 calls.




The output from the asynch server

Code:

blah@blah:~/Documents/nix-chat-ui$  ./select 127.0.0.1 12345
Listening for incoming connections.


Select() was successful.
./select: New connection from 127.0.0.1 on socket 4


Select() was successful.

Which you can see hangs.


The server code

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int main(int argc, char *argv[]) {
fd_set master;
// the temorary fd list for select call
fd_set read_fds;

struct sockaddr_in serv_addr, cli_addr;
struct hostent *server;
int fdmax;
int i, j;
FD_ZERO(&master);
FD_ZERO(&read_fds);

	if((argc < 3) && (argc > 4)) {
	printf("USAGE: %s + IP Address + Port No.\n", argv[0]);
	exit(EXIT_FAILURE);
	}

int debug;
	if(argc == 4) {
	debug = atoi(argv[3]);
	}

/* get the listener */
int sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if(sockfd < 0) {
	printf("SOCKET(-1) error --> %s.\n", strerror(errno));
	exit(EXIT_FAILURE);
	}
		else if((sockfd) && (debug == 1)) {
		printf("Successfully created socket.\n");
		}
int yes = 1;
int sockopt = setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int));
	if(sockopt == -1) {
	printf("SETSOCKOPT(-1) error --> %s.\n", strerror(errno));
	exit(EXIT_FAILURE);
	}
		else if((sockopt) && (debug == 1)){
		printf("Setsockopt() was successful.\n");
		}

server = gethostbyname(argv[1]); 
	if(server == NULL) {
	printf("GETHOSTBYNAME(NULL) error --> %s.\n", strerror(errno));
	exit(EXIT_FAILURE);
	}

		else if((server) && (debug == 1)) {
		printf("Successfuly got host by name.\n");
		}

int portno = atoi(argv[2]);
	if(portno < 0) {
	printf("ATOI(-1) error --> %s.\n", strerror(errno));
	exit(EXIT_FAILURE);
	}

	if((portno == 0) && (debug == 1)) {
	printf("ATOI(0) - DEBUG MSG --> %s.\n", strerror(errno));
	}

	if((portno) && (debug == 1)) {
	printf("Successfully binded to port %d.\n", portno);
	}

serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
//memcpy(&serv_addr.sin_addr.s_addr, server->h_addr, server->h_length);
serv_addr.sin_port = htons(portno);
memset(&(serv_addr.sin_zero), '\0', 8);

int binder = bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
	if(binder < 0) {
	printf("BIND(-1) error --> %s.\n", strerror(errno));
	exit(EXIT_FAILURE);
	}

	if((binder == 0) && (debug == 1)) {
	printf("BIND(0) - DEBUG MSG --> %s.\n", strerror(errno));
	}
	
	if((binder) && (debug == 1)) {
	printf("Bind was successful.\n");
	}

int listener = listen(sockfd, 10);
	if(listener < 0) {
	printf("Listen(-1) error --> %s.\n", strerror(errno));
	exit(EXIT_FAILURE);
	}

	if((listener == 0) && (debug == 1)) {
	printf("LISTEN(0) - DEBUG MSG --> %s.\n", strerror(errno));
	}
		else {
		printf("Listening for incoming connections.\n");
		 if((listener) && (debug == 1)) {
		 printf("Entering main loop.\n");
		 }
		}
 
FD_SET(sockfd, &master);
//Watch the current FD.
fdmax = sockfd; 

for( ; ; ) {
read_fds = master;
char buffer[4096];

int selector = select(fdmax+1, &read_fds, NULL, NULL, NULL);
	if(selector < 0) {
	printf("SELECT(-1) error --> %s.\n", strerror(errno));
	exit(EXIT_FAILURE);
	}

		else {
		printf("\n\nSelect() was successful.\n");
		}

// Run through the existing connections looking for data to be read
for(i = 0; i <= fdmax; i++) {
	if(FD_ISSET(i, &read_fds)) { 

	if(i == sockfd) {
	 if(debug == 1) {
	 printf("i == sockfd DEBUG MSG --> %s.\n", strerror(errno));
	 }

	socklen_t clilen;
	clilen = sizeof(cli_addr);

	int newsockfd = accept(sockfd, (struct sockaddr *)&cli_addr, &clilen);
	if(newsockfd < 0) {
	printf("Accept(-1) error --> %s.\n", strerror(errno));
	exit(EXIT_FAILURE);
	}

	if((newsockfd == 0) && (debug == 1)) {
	printf("ACCEPT(0) - DEBUG MSG --> %s.\n", strerror(errno));
	}

		else {
		 if(debug == 1) {
		 printf("Accept(1) was successful.\n");
		 }

		 // Add new FD to masterset.
		 FD_SET(newsockfd, &master); 
		 
		 if(debug == 1) {
		 printf("newsockfd == %d\n", newsockfd);
		 printf("fdmax == %d\n", fdmax);
		 }

		 if(newsockfd > fdmax) { 
		  if(debug == 1) {
		  printf("newsockfd > fdmax.\n");
		  printf("fdmax == newsockfd.\n");
		  }

		 fdmax = newsockfd;
		 } 

		 if((newsockfd < fdmax) && (debug == 1)) {
		 printf("newsockfd < fdmax.\n");
		 }

		 if((newsockfd == fdmax) && (debug == 1)) {
		 printf("newsockfd == fdmax.\n");
		 }

		printf("%s: New connection from %s on socket %d\n", argv[0], inet_ntoa(cli_addr.sin_addr), newsockfd);
		}
	}

		else { // Start of read loop
		ssize_t bytes_read = recv(i, buffer, sizeof(buffer), 0);
		 if(bytes_read <= 0) {

		 if(bytes_read < 0) {
		 printf("RECV(-1) error --> %s.\n", strerror(errno));
		 exit(EXIT_FAILURE);
		 }

		 if(bytes_read == 0) {
		 // Connection closed by remote host
		 printf("%s: socket %d hung up\n", argv[0], i);
		 }

		 FD_CLR(i, &master);
		 close(i);
		}

		else { // Start of inner read loop if true
		 if((bytes_read) && (debug == 1)) {
		 printf("Recieve was successful.\n");
		 }

		 FD_CLR(i, &master);
		 close(i);

		for(j = 0; j <= fdmax; j++) { // Start of inner for loop to send data
		// Echo message to all
		if(FD_ISSET(j, &read_fds)) {

		 if(debug == 1) {
		 printf("j is in the masterset.\n");
		 }

		if((j == sockfd) && (debug == 1)) {
		printf("j == sockfd DEBUG MSG --> %s.\n", strerror(errno));
		}

		if((j != sockfd) && (debug == 1)) {
		printf("j != sockfd DEBUG MSG --> %s.\n", strerror(errno));
		}

		if((j == i) && (debug == 1)) {
		printf("j == i DEBUG MSG --> %s.\n", strerror(errno));
		}

		if((j != i) && (debug == 1)) {
		printf("j != i DEBUG MSG --> %s.\n", strerror(errno));
		}

  		// Except the listener and ourselves 
		  if((j != sockfd) && (j != i)) {
		   if(debug == 1) {
		   printf("j != sockfd && j != i");
		   }

  	  	  ssize_t bytes_written = send(j, buffer, bytes_read, 0);
		  if(bytes_written < 0) {
  	  	  printf("WRITE(-1) error --> %s.\n", strerror(errno));
		  }

		  if((bytes_written == 0) && (debug == 1)) {
		  printf("WRITE(0) - DEBUG MSG --> %s.\n", strerror(errno));
		  }

		  if((bytes_written) && (debug == 1)) {
		  printf("WRITE(1) was successful.\n");
		  }

  		 }
		}
		} // End of inner for loop to send data
		} // Inner read if read > 0
	} // End of read loop
	}
	}
}

return 0;
}

I am sure the client is good. I have written many of them and they work with my regular synchrous servers but I'll post the client code anyway.

The client

Code:

#include <stdio.h> 
#include <string.h> 
#include <stdlib.h> 
#include <unistd.h> 
#include <sys/socket.h> 
#include <sys/types.h> 
#include <netdb.h> 
#include <netinet/in.h> 
#include <arpa/inet.h>
#include <errno.h>

int main(int argc, char *argv[]) {  
struct hostent *server; 
struct sockaddr_in serv_addr/*, cli_addr*/;

	if((argc < 3) && (argc > 4)) {
	fprintf(stderr, "Ussage: %s + IP Address + port No. Append a 1 to turn verbose on.\n", argv[0]);
	exit(EXIT_FAILURE);
	}

int debug;
	if(argc == 4) {
	debug = atoi(argv[3]);
	}


int sockfd = socket(AF_INET, SOCK_STREAM, 0); 
	if(sockfd < 0) {
	printf("SOCKET(-1) error ---> %s.\n", strerror(errno));
	exit(EXIT_FAILURE);
	}

	if((sockfd == 0) && (debug == 1)) {
	printf("SOCKET(0) error ---> %s.\n", strerror(errno));
	}

	if((sockfd) && (debug == 1)) {
	printf("DEBUG MSG --> SOCKET was successful.\n");
	}

int yes = 1; 
setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int));

bzero((char *) &serv_addr, sizeof(serv_addr)); 
server = gethostbyname(argv[1]); 
	if(server == NULL) {
	fprintf(stderr, "No such host.\n");
	printf("%s\n", strerror(errno)); 
	exit(EXIT_FAILURE);
	}

		else if((server) && (debug == 1)) {
		printf("DEBUG MSG - Successfully got host by name.\n");
		}

int portno = atoi(argv[2]);
	if(portno < 0) {
	printf("PORTNO(0) error ---> %s.\n", strerror(errno));
	}

	if((portno == 0) && (debug == 1)) {
	printf("DEBUG MSG - ATOI(0) error ---> %s.\n", strerror(errno));
	}

	if((portno) && (debug == 1)) {
	printf("Successfully binded to port %d.\n", portno);
	}

serv_addr.sin_family = AF_INET;
memcpy(&serv_addr.sin_addr.s_addr, server->h_addr, server->h_length); 
serv_addr.sin_port = htons(portno);

int connector = connect(sockfd, (const struct sockaddr *)&serv_addr, sizeof(serv_addr));
	if(connector < 0) { 
	fprintf(stderr, "%s. CONNECT()\n", strerror(errno));
	exit(EXIT_FAILURE);
	}

		else {
		printf("Made a connection to %s\n", inet_ntoa(serv_addr.sin_addr)); 
		}

for( ; ; )
{
char buffer[4096];

printf("Message: ");
fgets(buffer, sizeof(buffer), stdin);
ssize_t bytes_written = write(sockfd, buffer, strlen(buffer));
	if(bytes_written < 0) { 
	printf("WRITE(-1) error ---> %s.\n", strerror(errno));
	}

	if(bytes_written == 0) {
	//printf("WRITE(0) error ---> %s.\n", strerror(errno));
	printf("Nothing was written.\n");
	}

	if((bytes_written) && (debug == 1)) { 
	printf("DEBUG MSG - WRITE was successful.\n");
	}

ssize_t bytes_read = read(sockfd, buffer, sizeof(buffer));
	if(bytes_read < 0) {
        //fprintf(stderr, "Error reading message from %s\n", inet_ntoa(cli_addr.sin_addr));
        printf("READ(-1) error ---> %s.\n", strerror(errno));
        exit(EXIT_FAILURE);
        }

	//Test to see if the buffer is blank.
        if((bytes_read == 0) && (debug == 1)) {
        printf("READ(0) error ---> %s.\n", strerror(errno));
        }
		else {
		printf("server: %s", buffer);
		}

}

close(sockfd);

return 0;
}

I am missing some parameters to the read/recv calls or do I need to enable non-blocking mode??