This is a kind of stream multiplexer now (stdin input, TCP output to multiple clients), but closing clients is not handled yet.

ddcd.cpp

@@ -29,36 +29,33 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
 #include "ddcd.h"
-#include <signal.h>
+
-#include <stdio.h>
-#include <getopt.h>
-#include <string.h>
-#include <stdlib.h>
-#include <sys/socket.h>
-#include <netinet/in.h>
-#include <arpa/inet.h>
-#include <iostream>
-#include <vector>
-#include <unistd.h>
 
 #define SOFTWARE_NAME "ddcd"
 #define MSG_START SOFTWARE_NAME ": "
 
-typedef struct client_s
-{
-	struct sockaddr_in addr;
-	int socket;
-	pid_t pid;
-	int pipefd[2];
-} client_t;
-
 int host_port = 0;
 char host_address[100] = "127.0.0.1";
 int decimation = 0;
+int bufsize = 1024;
+int bufsizeall;
+char* buf;
+
+int set_nonblocking(int fd)
+{
+	int flagtmp;
+	if((flagtmp = fcntl(fd, F_GETFL))!=-1)
+		if((flagtmp = fcntl(fd, F_SETFL, flagtmp|O_NONBLOCK))!=-1)
+			return 0;
+	return 1;
+}
+
+client_t* this_client;
 
 int main(int argc, char* argv[])
 {
 	int c;
+	fd_set select_fds;
 	
 	for(;;)
 	{
@@ -66,9 +63,10 @@ int main(int argc, char* argv[])
 		static struct option long_options[] = {
 		   {"port",       required_argument, 0,  'p' },
 		   {"address",    required_argument, 0,  'a' },
-		   {"decimation", required_argument, 0,  'd' }
+		   {"decimation", required_argument, 0,  'd' },
+		   {"bufsize", required_argument, 	 0,  'b' }
 		};
-		c = getopt_long(argc, argv, "p:a:d:", long_options, &option_index);
+		c = getopt_long(argc, argv, "p:a:d:b:", long_options, &option_index);
 		if(c==-1) break;
 		switch (c) 
 		{
@@ -82,6 +80,9 @@ int main(int argc, char* argv[])
 		case 'd':
 			decimation=atoi(optarg);
 			break;
+		case 'b':
+			bufsize=atoi(optarg);
+			break;
 		case 0:
 		case '?':
 		case ':':
@@ -90,62 +91,125 @@ int main(int argc, char* argv[])
 		}
 	}
 	
-	if(!decimation) { fprintf(stderr, MSG_START "missing required command line argument, --decimation.\n"); exit(1); }
+	if(!decimation) error_exit(MSG_START "missing required command line argument, --decimation.\n");
-	if(!host_port) { fprintf(stderr, MSG_START "missing required command line argument, --port.\n"); exit(1); }
+	if(!host_port) error_exit(MSG_START "missing required command line argument, --port.\n");
 	
 	struct sockaddr_in addr_host;
     int listen_socket;
-	std::vector<client_t*> clients(10);
+	std::vector<client_t*> clients;
+	clients.reserve(100);
     listen_socket=socket(AF_INET,SOCK_STREAM,0);
+
+	int sockopt = 1;
+	if( setsockopt(listen_socket, SOL_SOCKET, SO_REUSEADDR, (char *)&sockopt, sizeof(sockopt)) == -1 )
+		error_exit(MSG_START "cannot set SO_REUSEADDR.\n");  //the best description on SO_REUSEADDR ever: http://stackoverflow.com/a/14388707/3182453
+
     memset(&addr_host,'0',sizeof(addr_host));
     addr_host.sin_family=AF_INET;
     addr_host.sin_port=htons(host_port);
 	addr_host.sin_addr.s_addr = INADDR_ANY;
 
     if( (addr_host.sin_addr.s_addr=inet_addr(host_address)) == INADDR_NONE ) 
-	{ fprintf(stderr, MSG_START "invalid host address.\n"); exit(1); }
+		error_exit(MSG_START "invalid host address.\n");
 
 	if( bind(listen_socket, (struct sockaddr*) &addr_host, sizeof(addr_host)) < 0 )
-	{ fprintf(stderr, MSG_START "cannot bind() address to the socket.\n"); exit(1); }
+		error_exit(MSG_START "cannot bind() address to the socket.\n");
 
 	if( listen(listen_socket, 10) == -1 )
-	{ fprintf(stderr, MSG_START "cannot listen() on socket.\n"); exit(1); }
+		error_exit(MSG_START "cannot listen() on socket.\n");
+
+	struct sockaddr_in addr_cli;
+	socklen_t addr_cli_len = sizeof(addr_cli);
+	int new_socket;
+
+	//The server will wait on these sockets later...
+
+
+	//Set stdin and listen_socket to non-blocking
+	if(set_nonblocking(STDIN_FILENO) || set_nonblocking(listen_socket))
+		error_exit(MSG_START "cannot set_nonblocking().\n");
+
+	bufsizeall = bufsize*sizeof(char);
+	buf = (char*)malloc(bufsizeall);
+
+	FD_ZERO(&select_fds);
+	FD_SET(listen_socket, &select_fds);
+	FD_SET(STDIN_FILENO, &select_fds);
+	int highfd = ((listen_socket>STDIN_FILENO)?listen_socket:STDIN_FILENO)  + 1;
 
 	for(;;)
 	{
-		struct sockaddr_in addr_cli;
+		//Let's wait until there is any new data to read, or any new connection!
-		socklen_t addr_cli_len = sizeof(addr_cli);
+		select(highfd, &select_fds, NULL, NULL, NULL);
-		int new_socket;
+
-			
+		//Is there a new client connection?
-		if( (new_socket = accept(listen_socket, (struct sockaddr*)&addr_cli, &addr_cli_len)) == -1)
+		if( (new_socket = accept(listen_socket, (struct sockaddr*)&addr_cli, &addr_cli_len)) != -1)
 		{ 
-			fprintf(stderr, MSG_START "cannot accept() a connection.\n"); 
+			this_client = new client_t;
-			continue; 
+			memcpy(&this_client->addr, &addr_cli, sizeof(this_client->addr));
+			this_client->socket = new_socket;
+			if(pipe(this_client->pipefd) == -1)
+			{ 
+				perror(MSG_START "cannot open new pipe() for the client.\n");
+				continue;
+			}
+			if(this_client->pid = fork())
+			{
+				//We're the parent
+				set_nonblocking(this_client->pipefd[1]);
+				clients.push_back(this_client);
+				printf("client pid: %d\n", this_client->pid);
+			}
+			else
+			{
+				//We're the client
+				client();
+				return 1;
+			}
 		}
 
-		client_t* new_client = new client_t;
+		int retval = read(STDIN_FILENO, buf, bufsizeall);
-		memcpy(&new_client->addr, &addr_cli, sizeof(new_client->addr));
+		if(retval==0)
-		new_client->socket = new_socket;
-		
-		if(new_client->pid = fork())
 		{
-			//We're the parent
+			//end of input stream, close clients and exit
-			clients.push_back(new_client);
-			printf("client pid: %d\n", new_client->pid);
 		}
-		else
+		else if(retval != -1)
 		{
-			//We're the client
+			for (int i=0;i<clients.size(); i++)
-			client();
+			{
-			break;
+				if(write(clients[i]->pipefd[1], buf, retval)==-1)
+					print_client(clients[i], "lost buffer, failed to write pipe");
+			}
 		}
+		//TODO: at the end, server closes pipefd[1] for client
+		//close(this_client->pipefd[1]);
 	}
 
 	return 0;
 }
 
+void print_client(client_t* client, const char* what)
+{
+	fprintf(stderr,MSG_START " (client %s:%d) %s\n", inet_ntoa(client->addr.sin_addr), client->addr.sin_port, what);
+}
+
+void client_cleanup()
+{
+	close(this_client->pipefd[0]);
+}
+
 void client()
 {
 	printf("I'm the client\n");
-	for(;;) sleep(1);	
+	for(;;)
+	{
+		read(this_client->pipefd[0],buf,bufsizeall);
+		send(this_client->socket,buf,bufsizeall,0);
+	}	
+}
+
+void error_exit(const char* why)
+{
+	perror(why);
+	exit(1);
 }

ddcd.h

@@ -1 +1,28 @@
+#pragma once
+
+#include <signal.h>
+#include <stdio.h>
+#include <getopt.h>
+#include <string.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <iostream>
+#include <vector>
+#include <unistd.h>
+#include <fcntl.h>
+
+typedef struct client_s
+{
+	struct sockaddr_in addr;
+	int socket;
+	pid_t pid;
+	int pipefd[2];
+} client_t;
+
+
 void client();
+void error_exit(const char* why);
+void print_client(client_t* client, const char* what);