This is native C code for linux that will make an easy to use messaging broker between peers.
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//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; } |