telnetd: fill hostname field in utmp/wtmp records

function                                             old     new   delta
get_lsa                                                -     109    +109
make_new_session                                     438     504     +66
get_peer_lsa                                           -      10     +10
ftpd_main                                           2340    2267     -73
get_sock_lsa                                         101      10     -91
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 1/2 up/down: 185/-164)           Total: 21 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

include/libbb.h

@@ -530,6 +530,8 @@ int create_and_connect_stream_or_die(const char *peer, int port) FAST_FUNC;
 int xconnect_stream(const len_and_sockaddr *lsa) FAST_FUNC;
 /* Get local address of bound or accepted socket */
 len_and_sockaddr *get_sock_lsa(int fd) FAST_FUNC RETURNS_MALLOC;
+/* Get remote address of connected or accepted socket */
+len_and_sockaddr *get_peer_lsa(int fd) FAST_FUNC RETURNS_MALLOC;
 /* Return malloc'ed len_and_sockaddr with socket address of host:port
  * Currently will return IPv4 or IPv6 sockaddrs only
  * (depending on host), but in theory nothing prevents e.g.

libbb/xconnect.c

@@ -47,25 +47,35 @@ int FAST_FUNC setsockopt_bindtodevice(int fd UNUSED_PARAM,
 }
 #endif
 
-len_and_sockaddr* FAST_FUNC get_sock_lsa(int fd)
+static len_and_sockaddr* get_lsa(int fd, int (*get_name)(int fd, struct sockaddr *addr, socklen_t *addrlen))
 {
 	len_and_sockaddr lsa;
 	len_and_sockaddr *lsa_ptr;
 
 	lsa.len = LSA_SIZEOF_SA;
-	if (getsockname(fd, &lsa.u.sa, &lsa.len) != 0)
+	if (get_name(fd, &lsa.u.sa, &lsa.len) != 0)
 		return NULL;
 
 	lsa_ptr = xzalloc(LSA_LEN_SIZE + lsa.len);
 	if (lsa.len > LSA_SIZEOF_SA) { /* rarely (if ever) happens */
 		lsa_ptr->len = lsa.len;
-		getsockname(fd, &lsa_ptr->u.sa, &lsa_ptr->len);
+		get_name(fd, &lsa_ptr->u.sa, &lsa_ptr->len);
 	} else {
 		memcpy(lsa_ptr, &lsa, LSA_LEN_SIZE + lsa.len);
 	}
 	return lsa_ptr;
 }
 
+len_and_sockaddr* FAST_FUNC get_sock_lsa(int fd)
+{
+	return get_lsa(fd, getsockname);
+}
+
+len_and_sockaddr* FAST_FUNC get_peer_lsa(int fd)
+{
+	return get_lsa(fd, getpeername);
+}
+
 void FAST_FUNC xconnect(int s, const struct sockaddr *s_addr, socklen_t addrlen)
 {
 	if (connect(s, s_addr, addrlen) < 0) {

networking/ftpd.c

@@ -461,21 +461,6 @@ handle_epsv(void)
 	free(response);
 }
 
-/* libbb candidate */
-static
-len_and_sockaddr* get_peer_lsa(int fd)
-{
-	len_and_sockaddr *lsa;
-	socklen_t len = 0;
-
-	if (getpeername(fd, NULL, &len) != 0)
-		return NULL;
-	lsa = xzalloc(LSA_LEN_SIZE + len);
-	lsa->len = len;
-	getpeername(fd, &lsa->u.sa, &lsa->len);
-	return lsa;
-}
-
 static void
 handle_port(void)
 {

networking/telnetd.c

@@ -226,6 +226,9 @@ make_new_session(
 		IF_FEATURE_TELNETD_STANDALONE(int sock)
 		IF_NOT_FEATURE_TELNETD_STANDALONE(void)
 ) {
+#if !ENABLE_FEATURE_TELNETD_STANDALONE
+	enum { sock = 0 );
+#endif
 	const char *login_argv[2];
 	struct termios termbuf;
 	int fd, pid;
@@ -243,9 +246,9 @@ make_new_session(
 	ndelay_on(fd);
 	close_on_exec_on(fd);
 
-#if ENABLE_FEATURE_TELNETD_STANDALONE
 	/* SO_KEEPALIVE by popular demand */
 	setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
+#if ENABLE_FEATURE_TELNETD_STANDALONE
 	ts->sockfd_read = sock;
 	ndelay_on(sock);
 	if (sock == 0) { /* We are called with fd 0 - we are in inetd mode */
@@ -256,8 +259,6 @@ make_new_session(
 	if (sock > G.maxfd)
 		G.maxfd = sock;
 #else
-	/* SO_KEEPALIVE by popular demand */
-	setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
 	/* ts->sockfd_read = 0; - done by xzalloc */
 	ts->sockfd_write = 1;
 	ndelay_on(0);
@@ -313,6 +314,17 @@ make_new_session(
 	/* Restore default signal handling ASAP */
 	bb_signals((1 << SIGCHLD) + (1 << SIGPIPE), SIG_DFL);
 
+	if (ENABLE_FEATURE_UTMP) {
+		len_and_sockaddr *lsa = get_peer_lsa(sock);
+		char *hostname = NULL;
+		if (lsa) {
+			hostname = xmalloc_sockaddr2dotted(&lsa->u.sa);
+			free(lsa);
+		}
+		write_new_utmp(pid, LOGIN_PROCESS, tty_name, /*username:*/ "LOGIN", hostname);
+		free(hostname);
+	}
+
 	/* Make new session and process group */
 	setsid();
 
@@ -326,9 +338,6 @@ make_new_session(
 	pid = getpid();
 	tcsetpgrp(0, pid); /* switch this tty's process group to us */
 
-//TODO: fetch remote addr via getpeername (see ftpd.c)
-	write_new_utmp(pid, LOGIN_PROCESS, tty_name, /*username:*/ "LOGIN", /*hostname:*/ NULL);
-
 	/* The pseudo-terminal allocated to the client is configured to operate
 	 * in cooked mode, and with XTABS CRMOD enabled (see tty(4)) */
 	tcgetattr(0, &termbuf);