This is native C code for linux that will make an easy to use messaging broker between peers.
//Example code: A simple server side code, which echos back the received message.
//Handle multiple socket connections with select and fd_set on Linux
#include <stdio.h>
#include <string.h> //strlen
#include <stdlib.h>
#include <errno.h>
#include <unistd.h> //close
#include <arpa/inet.h> //close
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/time.h> //FD_SET, FD_ISSET, FD_ZERO macros
#include <iostream> //Including this header may automatically include other headers, such as <ios>, <streambuf>, <istream>, <ostream> and/or <iosfwd>.
#include <string>
#define TRUE 1
#define FALSE 0
#define PORT 8080
#define max_clients 32
using namespace std;
class Client
{
public:
int client_socket;
unsigned long s_addr;
unsigned short sin_port;
char client_ip[32];
char client_agent[512];
char client_filter[32];
char client_store[512];
};
Client Clients[32]; //= {0, {0}}
int main(int argc , char *argv[])
{
int opt = TRUE;
int master_socket , addrlen , new_socket , activity, i , valread , sd;
int max_sd;
struct sockaddr_in address;
char buffer[1025]; //data buffer of 1K
//set of socket descriptors
fd_set readfds;
//a message
char *message = "ECHO Daemon v1.0 \r\n";
//initialise all client_socket[] to 0 so not checked
for (i = 0; i < max_clients; i++)
{
Clients[i].client_socket = 0;
}
//create a master socket
if( (master_socket = socket(AF_INET , SOCK_STREAM , 0)) == 0)
{
perror("socket failed");
exit(EXIT_FAILURE);
}
//set master socket to allow multiple connections ,
//this is just a good habit, it will work without this
if( setsockopt(master_socket, SOL_SOCKET, SO_REUSEADDR, (char *)&opt,
sizeof(opt)) < 0 )
{
perror("setsockopt");
exit(EXIT_FAILURE);
}
//type of socket created
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons( PORT );
//bind the socket to localhost port 8888
if (bind(master_socket, (struct sockaddr *)&address, sizeof(address))<0)
{
perror("bind failed");
exit(EXIT_FAILURE);
}
printf("Listener on port %d \n", PORT);
//try to specify maximum of 3 pending connections for the master socket
if (listen(master_socket, 3) < 0)
{
perror("listen");
exit(EXIT_FAILURE);
}
//accept the incoming connection
addrlen = sizeof(address);
puts("Waiting for connections ...");
while(TRUE)
{
//clear the socket set
FD_ZERO(&readfds);
//add master socket to set
FD_SET(master_socket, &readfds);
max_sd = master_socket;
//add child sockets to set
for ( i = 0 ; i < max_clients ; i++)
{
//socket descriptor
sd = Clients[i].client_socket;
//if valid socket descriptor then add to read list
if(sd > 0)
FD_SET( sd , &readfds);
//highest file descriptor number, need it for the select function
if(sd > max_sd)
max_sd = sd;
}
//wait for an activity on one of the sockets , timeout is NULL ,
//so wait indefinitely
activity = select( max_sd + 1 , &readfds , NULL , NULL , NULL);
if ((activity < 0) && (errno!=EINTR))
{
puts("select error");
}
//If something happened on the master socket ,
//then its an incoming connection
if (FD_ISSET(master_socket, &readfds))
{
if ((new_socket = accept(master_socket,
(struct sockaddr *)&address, (socklen_t*)&addrlen))<0)
{
perror("accept");
exit(EXIT_FAILURE);
}
//inform user of socket number - used in send and receive commands
printf("New connection, socket fd is %d , IP: %s port: %d \n" , new_socket , inet_ntoa(address.sin_addr) , ntohs(address.sin_port));
//send new connection greeting message
if( send(new_socket, message, strlen(message), 0) != strlen(message) )
{
perror("send");
}
puts("Welcome message sent successfully");
//add new socket to array of sockets
for (i = 0; i < max_clients; i++)
{
//if position is empty
if( Clients[i].client_socket == 0 )
{
Clients[i].client_socket = new_socket;
printf("Adding to list of sockets as %d\n" , i);
memset((void*)Clients[i].client_filter[0], 32, 0);
Clients[i].client_filter[0] = 0x255;
Clients[i].s_addr = address.sin_addr.s_addr;
Clients[i].sin_port = address.sin_port;
sprintf(Clients[i].client_ip, "%s", inet_ntoa(address.sin_addr));
break;
}
}
}
//else its some IO operation on some other socket
for (i = 0; i < max_clients; i++)
{
sd = Clients[i].client_socket;
if (FD_ISSET( sd , &readfds))
{
//Check if it was for closing , and also read the
//incoming message
if ((valread = read( sd , buffer, 1024)) == 0)
{
//Somebody disconnected , get his details and print
getpeername(sd , (struct sockaddr*)&address , (socklen_t*)&addrlen);
printf("Host disconnected %03d] ip %s:%d \n", i, inet_ntoa(address.sin_addr) , ntohs(address.sin_port));
//Close the socket and mark as 0 in list for reuse
close( sd );
Clients[i].client_socket = 0;
}
//Echo back the message that came in
else
{
//set the string terminating NULL byte on the end
//of the data read
buffer[valread] = '\0';
//send(sd , buffer , strlen(buffer) , 0 );
if (strncmp(buffer, "-list", 5) == 0)
{
getpeername(sd , (struct sockaddr*)&address , (socklen_t*)&addrlen);
sprintf(buffer, "You are from %s:%d \r\nClient List\r\n" , inet_ntoa(address.sin_addr) , ntohs(address.sin_port));
send(sd , buffer , strlen(buffer) , 0 );
for (int a = 0; a < max_clients; a++)
{
if (Clients[a].client_socket > 0 && a != i)
{
getpeername(Clients[a].client_socket, (struct sockaddr*)&address , (socklen_t*)&addrlen);
sprintf(buffer, "%03d]%s:%d\r\n" , a, inet_ntoa(address.sin_addr) , ntohs(address.sin_port));
send(sd , buffer , strlen(buffer) , 0 );
}
}
send(sd , "\r\n" , strlen("\r\n"), 0 ); //Send end of list
continue;
}
if (strncmp(buffer, "-agents", 7) == 0)
{
getpeername(sd , (struct sockaddr*)&address , (socklen_t*)&addrlen);
sprintf(buffer, "\r\nClient Agent List\r\n" , inet_ntoa(address.sin_addr) , ntohs(address.sin_port));
send(sd , buffer , strlen(buffer) , 0 );
for (int a = 0; a < max_clients; a++)
{
if (Clients[a].client_socket > 0 && a != i)
{
getpeername(Clients[a].client_socket, (struct sockaddr*)&address , (socklen_t*)&addrlen);
sprintf(buffer, "%03d]%s:%d\r\n%s\r\n" , a, inet_ntoa(address.sin_addr) , ntohs(address.sin_port), Clients[a].client_agent);
send(sd , buffer , strlen(buffer) , 0 );
}
}
send(sd , "\r\n" , strlen("\r\n"), 0 ); //Send end of list
continue;
}
if (strncmp(buffer, "-clearfilter", 12) == 0) //By default no one gets data
{
memset((void*)Clients[i].client_filter[0], 32, 0);
Clients[i].client_filter[0] = 0x0;
strcpy(buffer, "Filter cleared");
send(sd , buffer , strlen(buffer) , 0 );
continue;
}
if (strncmp(buffer, "-filter:", 8) == 0)
{
strncpy(&Clients[i].client_filter[0], &buffer[8], 32);
strcpy(buffer, "\r\nI got your filter: ");
send(sd , buffer , strlen(buffer) , 0 );
send(sd , &Clients[i].client_filter[0] , strlen(&Clients[i].client_filter[0]) , 0 );
continue;
}
if (strncmp(buffer, "-agent:", 7) == 0)
{
strncpy(&Clients[i].client_agent[0], &buffer[7], 512);
sprintf(buffer, "\r\nSetting Agent: %s\r\n", Clients[i].client_agent);
send(sd , buffer , strlen(buffer) , 0 );
send(sd , &Clients[i].client_agent[0] , strlen(&Clients[i].client_agent[0]) , 0 );
continue;
}
if (strncmp(buffer, "-server:", 8) == 0)
{
strncpy(&Clients[i].client_filter[0], &buffer[8], 32);
printf("%s", &buffer[8]);
continue;
}
if (strncmp(buffer, "-to:", 8) == 0)
{
strncpy(&Clients[i].client_filter[0], &buffer[8], 32);
printf("%s", &buffer[8]);
continue;
}
if (strncmp(buffer, "-invite:", 8) == 0)
{
char temp[8];
strncpy(&temp[0], &buffer[8], 4);
printf("inviting %s", temp);
int targetclient = atoi(temp);
printf("inviting %d", targetclient);
char invite[128];
sprintf(invite, "INVITE:%s", Clients[i].client_ip);
send(Clients[targetclient].client_socket, invite, strlen(invite), 0);
continue;
}
for (int a = 0; a < max_clients; a++)
{
//printf("%d - %d\r\n", a, i);
if (a != i)
{
if ((strncmp(buffer, &Clients[a].client_filter[0], strlen(&Clients[a].client_filter[0])) == 0) || Clients[a].client_filter[0] == 0x0)
{
send(Clients[a].client_socket, buffer , strlen(buffer) , 0 );
}
}
}
}
}
}
}
return 0;
}