added flood protection

connection.c

@@ -13,6 +13,13 @@
 #include "sockaddr.h"
 #include "tcpsocket.h"
 
+struct flood_ctrl {
+	int burst;
+	int current;
+	int inc_per_sec;
+	time_t last_inc;
+};
+
 struct connection {
 	struct list_head list;
 
@@ -23,6 +30,9 @@ struct connection {
 	struct event_fd *dst_event;
 	struct event_timeout *timeout;
 
+	struct flood_ctrl src_flood;
+	struct flood_ctrl dst_flood;
+
 	time_t login_time;
 };
 
@@ -37,7 +47,20 @@ static struct connection * create_connection()
 	}
 
 	memset(con, 0, sizeof(struct connection));
-	con->login_time = time(NULL);
+
+	time_t now = time(NULL);
+	con->login_time = now;
+
+	con->src_flood.burst = 256;
+	con->src_flood.inc_per_sec = 1;
+	con->src_flood.last_inc = now;
+
+	con->dst_flood.burst = 256;
+	con->dst_flood.inc_per_sec = 1;
+	con->dst_flood.last_inc = now;
+
+	con->src_flood.current = con->src_flood.burst;
+	con->dst_flood.current = con->dst_flood.burst;
 	return con;
 }
 
@@ -61,32 +84,95 @@ static void destroy_connection(struct connection *con)
 	free(con);
 }
 
+static int forward_throttle_timeout(void *privdata);
+
 static int forward_handler(int fd, void *privdata)
 {
 	struct connection *con = (struct connection *)privdata;
-	char buf[256];
 
-	int len = read(fd, buf, sizeof(buf));
-	if (len <= 0) {
+	int src_fd = event_get_fd(con->src_event);
+	int dst_fd = event_get_fd(con->dst_event);
+
+	struct event_fd *event;
+	struct flood_ctrl *flood;
+	int outfd;
+
+	/* client -> device */
+	if (src_fd == fd) {
+		flood = &con->dst_flood;
+		outfd = dst_fd;
+		event = con->src_event;
+
+	/* device -> client */
+	} else if (dst_fd == fd) {
+		flood = &con->src_flood;
+		outfd = src_fd;
+		event = con->dst_event;
+
+	/* unknown fd */
+	} else {
 		list_del(&con->list);
 		destroy_connection(con);
 		return -1;
 	}
 
-	int src_fd = event_get_fd(con->src_event);
-	int dst_fd = event_get_fd(con->dst_event);
+	/* increment quota */
+	time_t now = time(NULL);
+	flood->current += (flood->inc_per_sec * (now - flood->last_inc));
+	flood->last_inc = now;
 
-	/* client -> device */
-	if (src_fd == fd && dst_fd != -1)
-		write(dst_fd, buf, len);
+	/* max burst size */
+	if (flood->current > flood->burst)
+		flood->current = flood->burst;
 
-	/* device -> client */
-	if (dst_fd == fd && src_fd != -1)
-		write(src_fd, buf, len);
+	/* read max. buffer size */
+	char buf[256];
+	int readsize = sizeof(buf);
 
+	/* only read current quota */
+	if (readsize > flood->current)
+		readsize = flood->current;
+
+	/* no quota left */
+	if (readsize == 0) {
+		/* disable fd event */
+		event_add_readfd(event, 0, NULL, NULL);
+
+		/* setup timer to reenable fd-event */
+		struct timeval tv = { .tv_sec = 1, .tv_usec = 0 };
+		event_add_timeout(&tv, forward_throttle_timeout, con);
+
+		return 0;
+	}
+
+	int len = read(fd, buf, readsize);
+	if (len <= 0 && readsize > 0) {
+		list_del(&con->list);
+		destroy_connection(con);
+		return -1;
+	}
+
+	/* not forwarding: discard the data */
+	if (outfd == -1)
+		return 0;
+
+	write(outfd, buf, len);
+	flood->current -= len;
 	return 0;
 }
 
+static int forward_throttle_timeout(void *privdata)
+{
+	struct connection *con = (struct connection *)privdata;
+
+	/* HACK: enable both directions unconditionally */
+	event_add_readfd(con->dst_event, 0, forward_handler, con);
+	event_add_readfd(con->src_event, 0, forward_handler, con);
+
+	/* remove timeout again */
+	return -1;
+}
+
 static int connect_handler(int fd, void *privdata)
 {
 	struct connection *con = (struct connection *)privdata;
@@ -144,7 +230,7 @@ int client_handler(int fd, void *privdata)
 
 	// TODO: check destination
 
-	int dst_fd = tcp_connect(&con->dst_addr);
+	int dst_fd = tcp_connect_nonblock(&con->dst_addr);
 	if (dst_fd < 0) {
 		list_del(&con->list);
 		destroy_connection(con);

event.c

@@ -79,6 +79,7 @@ struct event_fd * event_add_fd(
 		}
 
 		memset(entry, 0, sizeof(struct event_fd));
+		entry->flags |= EVENT_NEW;
 		entry->fd = fd;
 
 		/* put it on the list */
@@ -96,7 +97,6 @@ struct event_fd * event_add_fd(
 		entry->write_priv = privdata;
 	}
 
-	entry->flags |= EVENT_NEW;
 	return entry;
 }
 
@@ -208,32 +208,6 @@ int event_loop(void)
 	}
 
 	while (1) {
-		fd_set *readfds = NULL, *writefds = NULL;
-		struct event_fd *entry, *tmp;
-
-		list_for_each_entry_safe(entry, tmp, &event_fd_list, list) {
-			entry->flags &= ~EVENT_NEW;
-
-			if (entry->flags & EVENT_DELETE) {
-				list_del(&entry->list);
-				free(entry);
-
-			} else if (entry->flags & FD_READ) {
-				if (readfds == NULL) {
-					readfds = &fdsets[0];
-					FD_ZERO(readfds);
-				}
-				FD_SET(entry->fd, readfds);
-
-			} else if (entry->flags & FD_WRITE) {
-				if (writefds == NULL) {
-					writefds = &fdsets[1];
-					FD_ZERO(writefds);
-				}
-				FD_SET(entry->fd, writefds);
-			}
-		}
-
 		struct timeval timeout, *timeout_p = NULL;
 		if (!list_empty(&event_timeout_list)) {
 			struct timeval now;
@@ -272,6 +246,32 @@ int event_loop(void)
 			}
 		}
 
+		fd_set *readfds = NULL, *writefds = NULL;
+		struct event_fd *entry, *tmp;
+
+		list_for_each_entry_safe(entry, tmp, &event_fd_list, list) {
+			entry->flags &= ~EVENT_NEW;
+
+			if (entry->flags & EVENT_DELETE) {
+				list_del(&entry->list);
+				free(entry);
+
+			} else if (entry->flags & FD_READ) {
+				if (readfds == NULL) {
+					readfds = &fdsets[0];
+					FD_ZERO(readfds);
+				}
+				FD_SET(entry->fd, readfds);
+
+			} else if (entry->flags & FD_WRITE) {
+				if (writefds == NULL) {
+					writefds = &fdsets[1];
+					FD_ZERO(writefds);
+				}
+				FD_SET(entry->fd, writefds);
+			}
+		}
+
 		int i = select(FD_SETSIZE, readfds, writefds, NULL, timeout_p);
 		if (i <= 0) {
 			/* On error, -1 is returned, and errno is set