From 3c84f22524decbb7a8b0d7fa805686e95f23e98d Mon Sep 17 00:00:00 2001
From: Michael Tremer <michael.tremer@ipfire.org>
Date: Thu, 28 Jan 2021 14:46:01 +0000
Subject: [PATCH] server: Gracefully close connections when the client went
 away

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---
 src/server.c | 50 +++++++++++++++++++++++++++++++++++---------------
 1 file changed, 35 insertions(+), 15 deletions(-)

diff --git a/src/server.c b/src/server.c
index 07a8a3f..67eeb27 100644
--- a/src/server.c
+++ b/src/server.c
@@ -29,6 +29,12 @@
 
 #define SOCKET_BACKLOG   1024
 
+// Struct to collect server statistics
+struct fireperf_server_stats {
+	// Total number of open connections
+	unsigned int connections;
+};
+
 static int create_socket(struct fireperf_config* conf) {
 	// Open a new socket
 	int fd = socket(AF_INET6, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
@@ -100,11 +106,6 @@ static int handle_io_on_connection(struct fireperf_config* conf, int fd) {
 	if (bytes_read < 0) {
 		ERROR(conf, "Could not read from socket %d: %s\n", fd, strerror(errno));
 		return -1;
-
-	// Connection closed
-	} else if (bytes_read == 0) {
-		DEBUG(conf, "Connection %d has closed\n", fd);
-		return 1;
 	}
 
 	DEBUG(conf, "Read %zu bytes from socket %d\n", bytes_read, fd);
@@ -113,6 +114,8 @@ static int handle_io_on_connection(struct fireperf_config* conf, int fd) {
 }
 
 int fireperf_server(struct fireperf_config* conf) {
+	struct fireperf_server_stats stats;
+
 	DEBUG(conf, "Launching " PACKAGE_NAME " in server mode\n");
 
 	int sockfd = -1;
@@ -169,7 +172,7 @@ int fireperf_server(struct fireperf_config* conf) {
 					goto ERROR;
 
 				// Add the new socket to epoll()
-				ev.events  = EPOLLIN;
+				ev.events  = EPOLLIN|EPOLLHUP;
 				ev.data.fd = connfd;
 
 				if (epoll_ctl(epollfd, EPOLL_CTL_ADD, connfd, &ev)) {
@@ -178,19 +181,36 @@ int fireperf_server(struct fireperf_config* conf) {
 					goto ERROR;
 				}
 
+				// A connection has been opened
+				stats.connections++;
+				continue;
+			}
+
+			// Handle any connection events (like disconnects)
+			if (ev.events & EPOLLHUP) {
+				DEBUG(conf, "Connection %d has closed\n", fd);
+
+				// Remove the file descriptor from epoll()
+				if (epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, NULL)) {
+					ERROR(conf, "Could not remove socket file descriptfor from epoll(): %s\n",
+						strerror(errno));
+				}
+
+				// Free up any resources
+				close(fd);
+
+				// This connection is now closed
+				stats.connections--;
+
+				// Skip processing anything else, because it would be pointless
+				continue;
+			}
+
 			// One of the connections had IO
-			} else {
+			if (ev.events & EPOLLIN) {
 				r = handle_io_on_connection(conf, fd);
 				if (r < 0)
 					goto ERROR;
-
-				// Connection closed?
-				else if (r == 1) {
-					if (epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, NULL)) {
-						ERROR(conf, "Could not remove socket file descriptfor from epoll(): %s\n",
-							strerror(errno));
-					}
-				}
 			}
 		}
 	}
-- 
2.47.2