Communication: Sending a message from a client to a server - c

Question

My Server can handle multiple clients/switches at a time.
My problem is in my switch I believe, I'm trying to send an open message to the the controller. I create the the tcp socket in the switch and then right after I try to send the message to the controller, however when I try to do this, the socket disconnects from the controller and goes into an infinite loop. I'm not sure why this occurs as I'm creating and sending the message outside of my while loop. If I comment where I send the message, the socket stays connected to the controller and I am able to wait for one of a set of file descriptors to become ready to perform I/O, currently I only have the keyboard and the socket. My socket also receives a message from the controller when it's connected "You are connected to the server". In addition since my switch socket disconnects my recv() return error code 107 due to the fact the socket is disconnected.
I'm not sure If I provided too much code to look through but I added comments where I thought my error was occurring in the switch as well as the controller. Greatly appreciated for some help. I didn't add any of my own header files because they are not necessary.
This where I execute the switch. Sends and receive messages here.
#include "switch.h"
#include "openFIFO.h"
#include "packets.h"
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/select.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include<poll.h>
#include <signal.h>
void do_switch(int swIport, char *trafficfile,int swJport, int swKport, int IPlow, int IPhigh,char serverAddress[256], unsigned short portNumber){
int switch_sock;
char server_response[256];
struct pollfd pfds[6];
int rval;
/* Switch */
Switch sw;
sw.swJport = swJport;
sw.swIport = swIport;
sw.swKport = swKport;
sw.IPlow = IPlow;
sw.IPhigh = IPhigh;
int switchLength = sizeof(Switch);
// printf("\n\nstruct switchLength: %d\n", switchLength);
// printf("\n\nSwitch Struct: swIport: %d, swJport: %d, swKport: %d,
IPlow: %d, IPhigh: %d\n", sw.swIport, sw.swJport, sw.swKport, sw.IPlow,
sw.IPhigh);
printf("\n\nSwitch created with the following: swIport: %d, trafficfile:
%s, swJport: %d, swKport: %d, IPlow: %d, IPhigh: %d, serverAddress: %s,
portNumber: %d\n", swIport, trafficfile, swJport, swKport, IPlow, IPhigh,
serverAddress, portNumber);
int fifoWrite[2];
int fifoRead[2];
int counter = 0;
char message[20] = "Hello";
/* Create fifos */
if(swJport != -1){
fifoWrite[0] = openWF(swIport,swJport);
fifoRead[0] = openReadFifo(swJport, swIport);
counter = counter + 2;
}
if(swKport != -1){
fifoWrite[1] = openWF(swIport,swKport);
fifoRead[1] = openReadFifo(swKport, swIport);
counter = counter + 2;
}else if(swKport == -1){
fifoWrite[0] = openWF(swIport,swKport);
fifoRead[0] = openReadFifo(swKport, swIport);
counter = counter + 2;
}
printf("fifoWrite[0]: %d\n", fifoWrite[0]);
printf("fifoRead[0]: %d\n", fifoRead[0]);
printf("fifoWrite[1]: %d\n", fifoWrite[1]);
printf("fifoRead[1]: %d\n", fifoRead[1]);
/* Establish connection between the controller and switch */
/* Send a open packet to the controller */
/* Sending a stuct */
//PROBELM HERE BELOW!!!!!!!
switch_sock = CreateTCPClientSocket(portNumber, serverAddress);
if(send(switch_sock, message, sizeof(message), 0) == -1){
fprintf(stderr, "Send() Failed");
}
else{
printf("Open packet is being sent to the controller\n");
}
/* Initialize poll parameters */
//Keyboard
pfds[0].fd = STDIN_FILENO;
pfds[0].events = POLLIN;
// Socket!
pfds[1].fd = switch_sock;
pfds[1].events = POLLIN;
printf("Starting switch............................\n\n");
while(1){
rval = poll(pfds,2,-1);
if(rval == 0){
fprintf(stderr, "Poll timed out. \n");
}if(rval == -1){
fprintf(stderr, "ERROR: poll() failed");
exit(0);
}
/* Check Keyboard */
if(pfds[0].revents & POLLIN && pfds[0].fd == 0){
int a;
char command[1024][256];
int commands;
char buf[256];
commands = read(0, buf, 256);
buf[commands] = '\0';
buf[commands] = '\0';
char *token;
token = strtok(buf, " ");
while(token != NULL){
strcpy(command[a], token);
a++;
token = strtok(NULL, " ");
}
a = 0;
bzero(buf, 256);
if(strcmp(command[0], "list") == 0){
//TODO: Make a print function
printf("print_switch()\n");
}
if(strcmp(command[0], "exit") == 0){
//TODO: Make a print function
printf(" print_switch()\n");
printf("switch-disconnected\n");
close(switch_sock);
exit(0)
}
}
/* Server sent a welcome message */
// Might be PROBELM HERE BELOW when trying to send the initial packet to
controller!!!!!!!
if(pfds[1].revents & POLLIN){
recv(switch_sock, &server_response, sizeof(server_response), 0);
printf("%s\n", server_response);
}
}
}
Creates a TCP Socket for the switch.
int CreateTCPClientSocket( unsigned short port, char *serverAddress){
int sock; /*socket to create */
struct sockaddr_in servAddr; /* Local address */
/* Construct local address structure */
/* Create socket for incoming connections */
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0){
fprintf(stderr,"ERROR: socket() failed\n");
exit(0);
}
memset(&servAddr, 0, sizeof(servAddr));
servAddr.sin_family = AF_INET;
servAddr.sin_port = htons(port);
servAddr.sin_addr.s_addr = inet_addr(serverAddress);
if(connect(sock, (struct sockaddr *)&servAddr, sizeof(struct sockaddr)) <
0){
printf("Error code: %d\n", errno);
fprintf(stderr, "ERROR: connect() just failed\n");
exit(0);
}
return sock;
}
This is the controller
#include "controller.h"
#include "packets.h"
#include "switch.h"
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/select.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
void do_controller(int nSwitch, int portNumber){
int controller_sock; /* Socket descriptor for server/controller */
int clnSocket; /*Socket descriptor for clients */
int activity;
int max_sd;
int sd;
int client_socket[nSwitch];
struct sockaddr_in address;
int addrlen;
/* Controller stuff */
Controller cont;
cont.ackCounter = 0;
cont.openCounter = 0;
Switch sw;
char message[256] = "You have reached the server\n";
char recv_message[20];
printf("\n\nController created: nSwitch: %d on portNumber: %d\n", nSwitch, portNumber);
/* Initialise all client_socket[] to 0 so not checked */
for(int i = 0; i < nSwitch; i++){
client_socket[i] = 0;
}
/*Create the server/controller socket */
controller_sock = CreateTCPServerSocket(portNumber);
//addrlen = sizeof(address);
/* Prepare for nonblocking I/O polling/select from the controller socket */
printf("Starting server.........\n\n");
while(1){
/* Zero the socket set and set for server sockets */
/* This must be reset every time select() is called */
/* Add keyboard to descriptor */
/* Add client and controller sockets to set */
FD_ZERO(&sockSet);
FD_SET(STDIN_FILENO, &sockSet);
FD_SET(controller_sock, &sockSet);
max_sd = controller_sock;
//max_sd = 0;
printf("nSwitch: %d\n", nSwitch);
for(int x = 0; x < nSwitch; x++){
sd = client_socket[x];
printf("sd: %d\n\n", sd);
if(sd > 0)
FD_SET(sd, &sockSet);
if(sd > max_sd)
max_sd = sd;
}
printf("max_sd: %d\n", max_sd);
//wait for one of the sockets, timeout is Null,
//so wait indefinitely
activity = select(max_sd + 1, &sockSet, NULL, NULL,NULL);
//printf("Activity: %d\n", activity);
if(activity < 0){
fprintf(stderr, "ERROR: select()\n");
exit(0);
}
/*Check keyboard */
if(FD_ISSET(STDIN_FILENO, &sockSet)){
int a;
char command[1024][256];
int commands;
char buf[256];
commands = read(0, buf, 256);
buf[commands] = '\0';
char *token;
token = strtok(buf, " ");
while(token != NULL){
strcpy(command[a], token);
a++;
token = strtok(NULL, " ");
}
a = 0;
bzero(buf, 256);
if(strcmp(command[0], "list") == 0){
//TODO: Make a print function
print_controller(&cont, nSwitch);
}
if(strcmp(command[0], "exit") == 0){
//TODO: Make a print function
print_controller(&cont, nSwitch);
exit(0);
}
continue;
}
/* Check the incoming FIFOS from the controller an attached switches */
/*If something happened on the controller socket,
then its an incomming connection. Accept new communitcation.Wait for a client to connect.
Recieve packets sent to the controller_sock
*/
if(FD_ISSET(controller_sock, &sockSet)){
clnSocket = AcceptTCPConnection(controller_sock);
if(send(clnSocket, message, sizeof(message), 0) != sizeof(message)){
fprintf(stderr, "Send()");
exit(0);
}
puts("Welcome message sent successfuly");
//PROBELM HERE BELOW!!!!!!! Returns error code 107 because the
socket disconnected.
recv(controller_sock, &recv_message, sizeof(recv_message), 0);
printf("This is my recv_message: %s\n", recv_message);
/*add new socket to array of sockets*/
for(int a = 0; a < nSwitch; a++){
/*if position is empty */
if(client_socket[a] == 0){
client_socket[a] = clnSocket;
printf("Adding to list of sockets as %d\n", client_socket[a]);
break;
}
}
}
/* Communicate with the sockets and handle TCP Client */
for(int z = 0; z <nSwitch; z++){
sd = client_socket[z];
/*Check if it was socket closed, and do other stuff */
if(FD_ISSET(sd ,&sockSet )){
getpeername(sd , (struct sockaddr*)&address , (socklen_t*)&addrlen);
printf("Host disconnected , ip %s , port %d \n" , inet_ntoa(address.sin_addr) , ntohs(address.sin_port));
close( sd );
client_socket[z] = 0;
}else{
//Do stuff for the client
printf("This is the client %d\n", sd);
}
}
}
}
These are the controllers functions: Assign a port to socket,Set socket to listen
int AcceptTCPConnection(int servSock){
int clntSock; /* Socket descriptor for client */
unsigned int clientAddressLen; /* sizeof(client_address); Length of client */
struct sockaddr_in cli_addr; /* Client address */
/* Set the size of the in-out parameter */
clientAddressLen = sizeof(cli_addr);
printf("ClientAddressLen: %x\n", clientAddressLen);
/* Wait for a client to connect */
if ((clntSock = accept(servSock, (struct sockaddr *) &cli_addr,
&clientAddressLen)) < 0){
fprintf(stderr, "ERROR: accept failed\n");
exit(0);
}
/* clntSock is connected to a client! */
//infrom user of socket number used in send and receive commands
printf("Handling client %s\n", inet_ntoa(cli_addr.sin_addr));
printf("New connection: socket fd is: %d, ip is: %s, port: %d\n\n",
clntSock, inet_ntoa(cli_addr.sin_addr), ntohs(cli_addr.sin_port));
return clntSock;
}
Create a TCP socket
int CreateTCPServerSocket(unsigned short port){
int sock; /* socket to create */
struct sockaddr_in servAddr; /* Local address */
/* Create socket for incoming connections */
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0){
fprintf(stderr,"ERROR: socket() failed\n");
exit(0);
}
/* Construct local address structure */
/* Define the server address */
//bzero((char *) &server_address, sizeof(server_address));
memset(&servAddr, 0, sizeof(servAddr)); /* Zero out structure */
servAddr.sin_family = AF_INET; /* Internet address family
*/
servAddr.sin_addr.s_addr = htonl(INADDR_ANY); /* Any incoming interface
*/
servAddr.sin_port = htons(port); /* Local port */
/* Bind to the local address */
printf("New connection: ip is: %s, port: %d\n\n",
inet_ntoa(servAddr.sin_addr), ntohs(servAddr.sin_port));
if (bind(sock, (struct sockaddr *) &servAddr, sizeof(servAddr)) < 0){
printf("Error code: %d\n", errno);
fprintf(stderr,"ERROR: bind() just failed\n");
exit(0);
}
/* Mark the socket so it will listen for incoming connections */
if (listen(sock, 5) < 0){
fprintf(stderr,"ERROR: listen() failed\n");
exit(0);
}
return sock;
}