Added argument to set limit on number of concurrent connections

src/wstationd.c

@@ -17,6 +17,7 @@
 #include <getopt.h>
 #include <poll.h>
 #include <syslog.h>
+#include <signal.h>
 #include "wstationd.h"
 
 
@@ -27,16 +28,18 @@
 // dictates the memory cost per connection.
 #define BUFFERSIZE 65539
 
-// Hard limit on number of concurrent connections
-#define SLOTLIMIT 128
-
 // Timeout for each connection, in seconds
 #define TIMEOUT 30
 
 
 static char *exec_name;
 
+// Should this application daemonize?
 static int daemonize = 1;
+// Hard limit on number of concurrent connections
+static int slotlimit = 128;
+// Used to handle signaled shutdowns
+static int keep_polling = 1;
 
 struct connection 
 {
@@ -50,10 +53,16 @@ struct connection
 
 static int write_connection(struct connection *);
 
+void shutdown_handler(int sig)
+{
+	keep_polling = 0;
+}
+
 static void print_help()
 {
-	fprintf(stdout, "usage: %s [-p port] [-b addr] directory\n", exec_name);
+	fprintf(stdout, "usage: %s [-d] [-l limit] [-p port] [-b addr] directory\n", exec_name);
 	fprintf(stdout, "  -d, --nodaemon        Do not detach and daemonize\n");
+	fprintf(stdout, "  -l, --limit <limit>   Set concurrent connection limit (default: 128)\n");
 	fprintf(stdout, "  -p, --port <port>     Port to listen on (default: 10800)\n");
 	fprintf(stdout, "  -b, --bind <address>  Address to bind to (default: 0.0.0.0)\n");
 	fprintf(stdout, "  -h, --help            Print this message and exit\n");
@@ -64,6 +73,7 @@ static void print_help()
 int main(int argc, char* argv[])
 {
 	const struct option longopts[] = {
+		{ "limit", required_argument, NULL, 'l' },
 		{ "nodaemon", required_argument, NULL, 'd' },
 		{ "port", required_argument, NULL, 'p' },
 		{ "bind", required_argument, NULL, 'b' },
@@ -77,8 +87,8 @@ int main(int argc, char* argv[])
 	int port = 10800; // Default port
 	uint32_t address = INADDR_ANY; // Default listen address
 
-	struct connection* conns[SLOTLIMIT];
+	struct connection** conns = NULL;
-	memset(conns, 0, sizeof(struct connection*) * SLOTLIMIT);
+	struct pollfd* fds = NULL;
 
 	if((exec_name = basename(argv[0])) == NULL){
 		fprintf(stderr, "%s: cannot get basename - %s\n",
@@ -93,6 +103,15 @@ int main(int argc, char* argv[])
 				daemonize = 0;
 			break;
 
+			case 'l':
+				slotlimit = (int)strtol(optarg, NULL, 10);
+				if(slotlimit < 1 || slotlimit > 1024){
+					fprintf(stderr, "%s: invalid limit (must be between 1 and 1024)\n", exec_name);
+					print_help();
+					goto shutdown_error;
+				}
+			break;
+			
 			case 'p':
 				port = (int)strtol(optarg, NULL, 10);
 				if(port < 1 || port > 65535){
@@ -135,6 +154,9 @@ int main(int argc, char* argv[])
 		goto shutdown_error;
 	}
 
+	// Handle signals
+	signal(SIGINT, shutdown_handler);
+
 	// Daemonize if requested
 	if(daemonize){
 		pid_t pid = fork();
@@ -228,16 +250,25 @@ int main(int argc, char* argv[])
 		goto shutdown_error;
 	}
 
-	struct pollfd fds[SLOTLIMIT+1];
+	fds = malloc(sizeof(struct pollfd) * (slotlimit + 1));
-	memset(&fds, 0, sizeof(struct pollfd) * (SLOTLIMIT + 1));
+	conns = malloc(sizeof(struct connection*) * slotlimit);
+	if(conns == NULL || fds == NULL){
+		if(daemonize){ syslog(LOG_ERR, "out of memory"); }
+		else { fprintf(stderr, "%s: out of memory\n", exec_name); }
+	}
+
+	memset(conns, 0, sizeof(struct connection*) * slotlimit);
+	memset(fds, 0, sizeof(struct pollfd) * (slotlimit + 1));
 
 	// Add sockfd
 	fds[0].fd = sockfd;
 	fds[0].events = POLLIN;
 	fds[0].revents = 0;
 
-	while(1){
+	while(keep_polling){
-		if(poll(fds, (SLOTLIMIT + 1), 1000) == -1){
+		if(poll(fds, (slotlimit + 1), 1000) == -1){
+			// Ignore interrupt generated errors
+			if(errno != EINTR){
 				if(daemonize){
 					syslog(LOG_ERR, "socket poll error - %s",
 						strerror(errno)
@@ -249,10 +280,11 @@ int main(int argc, char* argv[])
 				}
 				goto shutdown_error;
 			}
+		}
 
 		// Handle existing connections
 		int slotfirst = 0, slotfree = 0;
-		for(int i = 1; i <= SLOTLIMIT; i++){
+		for(int i = 1; i <= slotlimit; i++){
 			// Handle event
 			if(fds[i].revents & POLLIN){
 				ssize_t sz = recv(
@@ -390,12 +422,24 @@ int main(int argc, char* argv[])
 
 	shutdown_clean:
 	if(sockfd > 0) close(sockfd);
-	for(int i = 0; i < SLOTLIMIT; i++){ if(conns[i] != NULL) free(conns[i]); }
+	if(fds != NULL){ free(fds); fds = NULL; }
+	if(conns != NULL){
+		for(int i = 0; i < slotlimit; i++){
+			if(conns[i] != NULL) free(conns[i]);
+		}
+		free(conns); conns = NULL;
+	}
 	return 0;
 
 	shutdown_error:
 	if(sockfd > 0) close(sockfd);
-	for(int i = 0; i < SLOTLIMIT; i++){ if(conns[i] != NULL) free(conns[i]); }
+	if(fds != NULL){ free(fds); fds = NULL; }
+	if(conns != NULL){
+		for(int i = 0; i < slotlimit; i++){
+			if(conns[i] != NULL) free(conns[i]);
+		}
+		free(conns); conns = NULL;
+	}
 	return 1;
 }