xref: /netbsd-src/external/bsd/libevent/dist/sample/hello-world.c (revision 657871a79c9a2060a6255a242fa1a1ef76b56ec6)
1 /*	$NetBSD: hello-world.c,v 1.1.1.3 2021/04/07 02:43:15 christos Exp $	*/
2 /*
3   This example program provides a trivial server program that listens for TCP
4   connections on port 9995.  When they arrive, it writes a short message to
5   each client connection, and closes each connection once it is flushed.
6 
7   Where possible, it exits cleanly in response to a SIGINT (ctrl-c).
8 */
9 
10 
11 #include <string.h>
12 #include <errno.h>
13 #include <stdio.h>
14 #include <signal.h>
15 #ifndef _WIN32
16 #include <netinet/in.h>
17 # ifdef _XOPEN_SOURCE_EXTENDED
18 #  include <arpa/inet.h>
19 # endif
20 #include <sys/socket.h>
21 #endif
22 
23 #include <event2/bufferevent.h>
24 #include <event2/buffer.h>
25 #include <event2/listener.h>
26 #include <event2/util.h>
27 #include <event2/event.h>
28 
29 static const char MESSAGE[] = "Hello, World!\n";
30 
31 static const int PORT = 9995;
32 
33 static void listener_cb(struct evconnlistener *, evutil_socket_t,
34     struct sockaddr *, int socklen, void *);
35 static void conn_writecb(struct bufferevent *, void *);
36 static void conn_eventcb(struct bufferevent *, short, void *);
37 static void signal_cb(evutil_socket_t, short, void *);
38 
39 int
main(int argc,char ** argv)40 main(int argc, char **argv)
41 {
42 	struct event_base *base;
43 	struct evconnlistener *listener;
44 	struct event *signal_event;
45 
46 	struct sockaddr_in sin = {0};
47 #ifdef _WIN32
48 	WSADATA wsa_data;
49 	WSAStartup(0x0201, &wsa_data);
50 #endif
51 
52 	base = event_base_new();
53 	if (!base) {
54 		fprintf(stderr, "Could not initialize libevent!\n");
55 		return 1;
56 	}
57 
58 	sin.sin_family = AF_INET;
59 	sin.sin_port = htons(PORT);
60 
61 	listener = evconnlistener_new_bind(base, listener_cb, (void *)base,
62 	    LEV_OPT_REUSEABLE|LEV_OPT_CLOSE_ON_FREE, -1,
63 	    (struct sockaddr*)&sin,
64 	    sizeof(sin));
65 
66 	if (!listener) {
67 		fprintf(stderr, "Could not create a listener!\n");
68 		return 1;
69 	}
70 
71 	signal_event = evsignal_new(base, SIGINT, signal_cb, (void *)base);
72 
73 	if (!signal_event || event_add(signal_event, NULL)<0) {
74 		fprintf(stderr, "Could not create/add a signal event!\n");
75 		return 1;
76 	}
77 
78 	event_base_dispatch(base);
79 
80 	evconnlistener_free(listener);
81 	event_free(signal_event);
82 	event_base_free(base);
83 
84 	printf("done\n");
85 	return 0;
86 }
87 
88 static void
listener_cb(struct evconnlistener * listener,evutil_socket_t fd,struct sockaddr * sa,int socklen,void * user_data)89 listener_cb(struct evconnlistener *listener, evutil_socket_t fd,
90     struct sockaddr *sa, int socklen, void *user_data)
91 {
92 	struct event_base *base = user_data;
93 	struct bufferevent *bev;
94 
95 	bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
96 	if (!bev) {
97 		fprintf(stderr, "Error constructing bufferevent!");
98 		event_base_loopbreak(base);
99 		return;
100 	}
101 	bufferevent_setcb(bev, NULL, conn_writecb, conn_eventcb, NULL);
102 	bufferevent_enable(bev, EV_WRITE);
103 	bufferevent_disable(bev, EV_READ);
104 
105 	bufferevent_write(bev, MESSAGE, strlen(MESSAGE));
106 }
107 
108 static void
conn_writecb(struct bufferevent * bev,void * user_data)109 conn_writecb(struct bufferevent *bev, void *user_data)
110 {
111 	struct evbuffer *output = bufferevent_get_output(bev);
112 	if (evbuffer_get_length(output) == 0) {
113 		printf("flushed answer\n");
114 		bufferevent_free(bev);
115 	}
116 }
117 
118 static void
conn_eventcb(struct bufferevent * bev,short events,void * user_data)119 conn_eventcb(struct bufferevent *bev, short events, void *user_data)
120 {
121 	if (events & BEV_EVENT_EOF) {
122 		printf("Connection closed.\n");
123 	} else if (events & BEV_EVENT_ERROR) {
124 		printf("Got an error on the connection: %s\n",
125 		    strerror(errno));/*XXX win32*/
126 	}
127 	/* None of the other events can happen here, since we haven't enabled
128 	 * timeouts */
129 	bufferevent_free(bev);
130 }
131 
132 static void
signal_cb(evutil_socket_t sig,short events,void * user_data)133 signal_cb(evutil_socket_t sig, short events, void *user_data)
134 {
135 	struct event_base *base = user_data;
136 	struct timeval delay = { 2, 0 };
137 
138 	printf("Caught an interrupt signal; exiting cleanly in two seconds.\n");
139 
140 	event_base_loopexit(base, &delay);
141 }
142