From 8acc060eef3799b0f3f8c7601c67870f553795c7 Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Thu, 30 Apr 2020 21:06:39 +0200
Subject: Made server and client non-blocking

---
 plop.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 64 insertions(+), 14 deletions(-)

diff --git a/plop.c b/plop.c
index eb27125..931618e 100644
--- a/plop.c
+++ b/plop.c
@@ -1,4 +1,7 @@
+#include <errno.h>
+#include <fcntl.h>
 #include <netdb.h>
+#include <poll.h>
 #include <string.h>
 #include <sys/socket.h>
 #include <sys/types.h>
@@ -35,6 +38,12 @@ int make_server(const char * node, const char * service)
 		if (-1 == server)
 			continue;
 
+		if (-1 == fcntl(server, F_SETFL, (fcntl(server, F_GETFL, 0) | O_NONBLOCK)))
+		{
+			close(server);
+			continue;
+		}
+
 		if (0 == bind(server, it->ai_addr,it->ai_addrlen))
 			break;
 
@@ -56,6 +65,42 @@ int make_server(const char * node, const char * service)
 	return server;
 }
 
+/// Progresses the connection for a client and shifts it back in the array.
+/// `pfd` must be at least `shift_by + 1`-th element of the array.
+/// \param pfd Element in array processed by poll
+/// \param shift_by Element will be moved by in array this many indices
+/// \return Shift value for next handler
+/// \see poll(2)
+int handle_client(struct pollfd * pfd, const int shift_by)
+{
+	if (0 == pfd->revents)
+	{
+		return shift_by;
+	}
+
+	if (~(POLLIN | POLLOUT) & pfd->revents)
+	{
+		return -1; // TODO: Handle errors properly
+	}
+
+	static const char * response =
+		"HTTP/1.1 200 OK\r\n"
+		"Content-Type: text/plain; charset=utf-8\r\n"
+		"\r\n"
+		"plop\n";
+
+	if (-1 == send(pfd->fd, response, strlen(response), 0))
+	{
+		// TODO: Handle errors properly
+	}
+
+	close(pfd->fd);
+	(pfd - shift_by)->fd = -1;
+	(pfd - shift_by)->events = pfd->events;
+
+	return shift_by + 1;
+}
+
 /// Standard entry point for the program.
 /// \param argc Argument count
 /// \param argv Argument array
@@ -67,26 +112,31 @@ int main(int argc, char ** argv)
 		return 4;
 	}
 
-	int server = make_server(NULL, argv[1]);
+	struct pollfd fdv[200];
+	memset(fdv, 0, sizeof(fdv));
 
-	int client;
-	static const char * response =
-		"HTTP/1.1 200 OK\r\n"
-		"Content-Type: text/plain; charset=utf-8\r\n"
-		"\r\n"
-		"plop\n";
+	fdv[0].fd = make_server(NULL, argv[1]);
+	fdv[0].events = POLLIN;
+	int fdc = 1;
 
-	for (;;)
+	while (-1 != poll(fdv, fdc, -1))
 	{
-		if (-1 != (client = accept(server, NULL, NULL)))
+		int shift_by = 0;
+
+		for (int i = 1; i < fdc; ++i)
+		{
+			shift_by = handle_client(&fdv[i], shift_by);
+		}
+
+		fdc = fdc - shift_by;
+
+		if (POLLIN == fdv[0].revents)
 		{
-			if (-1 == send(client, response, strlen(response), 0))
+			if (-1 != (fdv[fdc].fd = accept(fdv[0].fd, NULL, NULL)))
 			{
-				// TODO: Handle errors properly
+				fdv[fdc].events = POLLIN | POLLOUT;
+				fdc++;
 			}
-
-			// Ignore the close-related error mess.
-			close(client);
 		}
 	}
 }
-- 
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