examples

commit f8cd81701c9ca4b161748ea198c9e5e73bd51895
parent 6f49ef2b8f25abbe4a5702b0b767aea9ecdeb97e
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Tue, 16 Aug 2022 00:22:43 +0100

epoll: Add TCP support

Diffstat:
M
src/epoll.c
 | 
109
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------

1 file changed, 99 insertions(+), 10 deletions(-)
diff --git a/src/epoll.c b/src/epoll.c
@@ -2,6 +2,10 @@
 #include <sys/timerfd.h>
 #include <sys/signalfd.h>
 #include <sys/inotify.h>
+#include <sys/socket.h>
+#include <netinet/ip.h>
+#include <netinet/tcp.h>
+
 #include <signal.h>
 #include <unistd.h>
 #include <stdio.h>
@@ -12,7 +16,8 @@
 #include <err.h>
 #include <errno.h>
 
-static int timer, signals, notifications, event_queue;
+static int timer, signals, notifications, tcp_socket, connection = -1, event_queue;
+static char** args;
 
 static void check_err(char const* msg)
 {
@@ -20,6 +25,29 @@ static void check_err(char const* msg)
 		err(1, "%s", msg);
 }
 
+static void puts_all(char const* msg)
+{
+	size_t len = strlen(msg);
+	char buf[len];
+
+	memcpy(buf, msg, len);
+	buf[len] = '\n';
+
+	write(STDOUT_FILENO, buf, len+1);
+	if (connection >= 0)
+		write(connection, buf, len+1);
+	check_err("write");
+}
+
+static void add_epollin(int fd, void(*cb)())
+{
+	epoll_ctl(event_queue, EPOLL_CTL_ADD, fd, &(struct epoll_event){
+		.events = EPOLLIN,
+		.data.ptr = cb,
+	});
+	check_err("epoll_ctl");
+}
+
 static void stdin_event(void)
 {
 	char buf[64];
@@ -27,7 +55,7 @@ static void stdin_event(void)
 
 	if (n <= 0)
 	{
-		puts("Stdin closed.");
+		puts_all("Stdin closed.");
 		exit(0);
 	}
 	for (int i = 0; i < n; ++i)
@@ -36,6 +64,8 @@ static void stdin_event(void)
 	buf[n] = '\0';
 
 	printf("Stdin: '%s'\n", buf);
+	if (connection >= 0)
+		dprintf(connection, "Stdin: '%s'\n", buf);
 }
 
 static void timerfd_event(void)
@@ -45,6 +75,8 @@ static void timerfd_event(void)
 	read(timer, &new_ticks, sizeof new_ticks);
 	ticks += new_ticks;
 	printf("Timer: +%lu %lu\n", new_ticks, ticks);
+	if (connection >= 0)
+		dprintf(connection, "Timer: +%lu %lu\n", new_ticks, ticks);
 }
 
 static void signalfd_event(void)
@@ -61,21 +93,64 @@ static void inotify_event(void)
 	struct inotify_event buf;
 	read(notifications, &buf, sizeof buf);
 	check_err("read");
-	puts("Executable updated, exiting...");
-	exit(0);
+	puts_all("Executable updated, restarting...");
+	sleep(1);
+	close(timer);
+	close(signals);
+	close(notifications);
+	close(tcp_socket);
+	close(connection);
+	close(event_queue);
+	execv(args[0], args);
+	check_err("execv");
+	exit(1);
 }
 
-static void add_epollin(int fd, void(*cb)())
+static void recv_event(void)
 {
-	epoll_ctl(event_queue, EPOLL_CTL_ADD, fd, &(struct epoll_event){
-		.events = EPOLLIN,
-		.data.ptr = cb,
-	});
-	check_err("epoll_ctl");
+	char buf[64];
+
+	int n = read(connection, buf, sizeof buf - 1);
+
+	if (n <= 0)
+	{
+		puts("Connection closed.");
+		close(connection);
+		connection = -1;
+		return;
+	}
+	for (int i = 0; i < n; ++i)
+		if (iscntrl(buf[i]))
+			buf[i] = '.';
+	buf[n] = '\0';
+
+	printf("TCP: '%s'\n", buf);
+}
+
+static void connect_event(void)
+{
+	char const buf[] = "Hello, outside world!\n";
+	struct sockaddr_in client;
+	socklen_t len = sizeof client;
+
+	puts_all("TCP: greeting guest");
+
+	if (connection >= 0)
+	{
+		close(connection);
+		check_err("close");
+	}
+
+	connection = accept(tcp_socket, (struct sockaddr*)&client, &len);
+	check_err("accept");
+	write(connection, buf, sizeof buf);
+	check_err("write");
+	add_epollin(connection, recv_event);
 }
 
 int main(int, char* argv[])
 {
+	args = argv;
 	timer = timerfd_create(CLOCK_MONOTONIC, 0);
 	check_err("timerfd_create");
 	timerfd_settime(timer, 0, &(struct itimerspec){
@@ -99,12 +174,26 @@ int main(int, char* argv[])
 	inotify_add_watch(notifications, argv[0], IN_ATTRIB | IN_MASK_CREATE);
 	check_err("inotify_add_watch");
 
+	int const reuseaddr = 1;
+	tcp_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+	check_err("socket");
+	setsockopt(tcp_socket, SOL_SOCKET, SO_REUSEADDR, &reuseaddr, sizeof reuseaddr);
+	check_err("setsockopt");
+	bind(tcp_socket, (const struct sockaddr*)&(struct sockaddr_in){
+		.sin_family = AF_INET,
+		.sin_port = htons(1337),
+		.sin_addr = {.s_addr = htonl(INADDR_ANY)}
+	}, sizeof (struct sockaddr_in));
+	check_err("bind");
+	listen(tcp_socket, 1);
+
 	event_queue = epoll_create1(0);
 	check_err("epoll_create1");
 	add_epollin(STDIN_FILENO, stdin_event);
 	add_epollin(timer, timerfd_event);
 	add_epollin(signals, signalfd_event);
 	add_epollin(notifications, inotify_event);
+	add_epollin(tcp_socket, connect_event);
 
 	puts("\nepoll: processing events...");
 	for (;;)