Add skeleton for listen and bind TCP sockets

discardd.c

@@ -12,10 +12,101 @@
  */
 
 #include <err.h>
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+
+#define nelems(_a) (sizeof((_a)) / sizeof((_a)[0]))
+
+static void
+print_listen_address(const struct sockaddr *sa, socklen_t salen, int family)
+{
+	char host[NI_MAXHOST], serv[NI_MAXSERV];
+	int error;
+	int flags = NI_NUMERICHOST | NI_NUMERICSERV;
+
+	error = getnameinfo(sa, salen, host, NI_MAXHOST, serv, NI_MAXSERV,
+	    flags);
+	if (error) {
+		warnx("%s", gai_strerror(error));
+	} else {
+		if (family == AF_INET6)
+			fprintf(stderr, "Listening on [%s]:%s\n", host, serv);
+		else
+			fprintf(stderr, "Listening on %s:%s\n", host, serv);
+	}
+}
+
+static void
+listen_sock_setup(const char *port, int socktype, int *s, size_t *maxsocks)
+{
+	struct addrinfo hints, *res, *res0;
+	const char *cause = NULL;
+	int error, save_errno, nsock;
+
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = AF_UNSPEC;
+	hints.ai_socktype = socktype;
+	hints.ai_flags = AI_PASSIVE;
+
+	error = getaddrinfo(NULL, port, &hints, &res0);
+	if (error)
+		errx(1, "%s", gai_strerror(error));
+
+	nsock = 0;
+	for (res = res0; res && nsock < *maxsocks; res = res->ai_next) {
+		s[nsock] = socket(res->ai_family, res->ai_socktype,
+		    res->ai_protocol);
+		if (s[nsock] == -1) {
+			cause = "socket";
+			continue;
+		}
+
+		if (bind(s[nsock], res->ai_addr, res->ai_addrlen) == -1) {
+			cause = "bind";
+			save_errno = errno;
+			close(s[nsock]);
+			errno = save_errno;
+			continue;
+		}
+
+		if (listen(s[nsock], 5) == -1) {
+			cause = "listen";
+			continue;
+		}
+
+		print_listen_address(res->ai_addr, res->ai_addrlen,
+		    res->ai_family);
+		nsock++;
+	}
+	if (nsock == 0)
+		err(1, "%s", cause);
+	freeaddrinfo(res0);
+
+	*maxsocks = nsock;
+}
+
+static void
+handle_tcp(const char *port)
+{
+	int s[8];
+	size_t nsocks = nelems(s);
+
+	listen_sock_setup(port, SOCK_STREAM, s, &nsocks);
+}
+
+static void
+handle_udp(const char *port)
+{
+	errx(1, "UDP unimplemented");
+}
+
 static void
 usage(void)
 {
@@ -54,9 +145,9 @@ main(int argc, char *argv[])
 	if (do_tcp && do_udp)
 		errx(1, "-t and -u are mutually exclusive");
 	if (do_udp)
-		errx(1, "UDP unimplemented");
+		handle_udp(port);
 	if (do_tcp)
-		errx(1, "TCP unimplemented");
+		handle_tcp(port);
 
 	return 0;
 }