1 files changed, 286 insertions, 213 deletions

diff --git a/sshd.c b/sshd.c
index d65671ddd..c4b1d1dfe 100644
--- a/sshd.c
+++ b/sshd.c
@@ -11,7 +11,7 @@
  */
 
 #include "includes.h"
-RCSID("$Id: sshd.c,v 1.31 1999/11/24 23:42:08 damien Exp $");
+RCSID("$Id: sshd.c,v 1.32 1999/11/25 00:54:59 damien Exp $");
 
 #include "xmalloc.h"
 #include "rsa.h"
@@ -65,12 +65,16 @@ char *av0;
 /* Saved arguments to main(). */
 char **saved_argv;
 
-/* This is set to the socket that the server is listening; this is used in
-   the SIGHUP signal handler. */
+/*
+ * This is set to the socket that the server is listening; this is used in
+ * the SIGHUP signal handler.
+ */
 int listen_sock;
 
-/* the client's version string, passed by sshd2 in compat mode.
-   if != NULL, sshd will skip the version-number exchange */
+/*
+ * the client's version string, passed by sshd2 in compat mode. if != NULL,
+ * sshd will skip the version-number exchange
+ */
 char *client_version_string = NULL;
 
 /* Flags set in auth-rsa from authorized_keys flags.  These are set in auth-rsa.c. */
@@ -88,19 +92,23 @@ struct envstring *custom_environment = NULL;
 /* Session id for the current session. */
 unsigned char session_id[16];
 
-/* Any really sensitive data in the application is contained in this structure.
-   The idea is that this structure could be locked into memory so that the
-   pages do not get written into swap.  However, there are some problems.
-   The private key contains BIGNUMs, and we do not (in principle) have
-   access to the internals of them, and locking just the structure is not
-   very useful.  Currently, memory locking is not implemented. */
+/*
+ * Any really sensitive data in the application is contained in this
+ * structure. The idea is that this structure could be locked into memory so
+ * that the pages do not get written into swap.  However, there are some
+ * problems. The private key contains BIGNUMs, and we do not (in principle)
+ * have access to the internals of them, and locking just the structure is
+ * not very useful.  Currently, memory locking is not implemented.
+ */
 struct {
         RSA *private_key;        /* Private part of server key. */
         RSA *host_key;           /* Private part of host key. */
 } sensitive_data;
 
-/* Flag indicating whether the current session key has been used.  This flag
-   is set whenever the key is used, and cleared when the key is regenerated. */
+/*
+ * Flag indicating whether the current session key has been used.  This flag
+ * is set whenever the key is used, and cleared when the key is regenerated.
+ */
 int key_used = 0;
 
 /* This is set to true when SIGHUP is received. */
@@ -466,7 +474,7 @@ main(int ac, char **av)
                         fprintf(stderr, "sshd version %s\n", SSH_VERSION);
                         fprintf(stderr, "Usage: %s [options]\n", av0);
                         fprintf(stderr, "Options:\n");
-                        fprintf(stderr, "  -f file    Configuration file (default %s/sshd_config)\n", ETCDIR);
+                        fprintf(stderr, "  -f file    Configuration file (default %s)\n", SERVER_CONFIG_FILE);
                         fprintf(stderr, "  -d         Debugging mode\n");
                         fprintf(stderr, "  -i         Started from inetd\n");
                         fprintf(stderr, "  -q         Quiet (no logging)\n");
@@ -614,13 +622,11 @@ main(int ac, char **av)
                 setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, (void *) &linger,
                            sizeof(linger));
 
-                /* Initialize the socket address. */
                 memset(&sin, 0, sizeof(sin));
                 sin.sin_family = AF_INET;
                 sin.sin_addr = options.listen_addr;
                 sin.sin_port = htons(options.port);
 
-                /* Bind the socket to the desired port. */
                 if (bind(listen_sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) {
                         error("bind: %.100s", strerror(errno));
                         shutdown(listen_sock, SHUT_RDWR);
@@ -628,12 +634,13 @@ main(int ac, char **av)
                         fatal("Bind to port %d failed.", options.port);
                 }
                 if (!debug_flag) {
-                        /* Record our pid in /etc/sshd_pid to make it
-                           easier to kill the correct sshd.  We don\'t
-                           want to do this before the bind above because
-                           the bind will fail if there already is a
-                           daemon, and this will overwrite any old pid in
-                           the file. */
+                        /*
+                         * Record our pid in /etc/sshd_pid to make it easier
+                         * to kill the correct sshd.  We don\'t want to do
+                         * this before the bind above because the bind will
+                         * fail if there already is a daemon, and this will
+                         * overwrite any old pid in the file.
+                         */
                         f = fopen(SSH_DAEMON_PID_FILE, "w");
                         if (f) {
                                 fprintf(f, "%u\n", (unsigned int) getpid());
@@ -666,8 +673,10 @@ main(int ac, char **av)
                 /* Arrange SIGCHLD to be caught. */
                 signal(SIGCHLD, main_sigchld_handler);
 
-                /* Stay listening for connections until the system crashes
-                   or the daemon is killed with a signal. */
+                /*
+                 * Stay listening for connections until the system crashes or
+                 * the daemon is killed with a signal.
+                 */
                 for (;;) {
                         if (received_sighup)
                                 sighup_restart();
@@ -682,12 +691,16 @@ main(int ac, char **av)
                                 error("accept: %.100s", strerror(errno));
                                 continue;
                         }
-                        /* Got connection.  Fork a child to handle it,
-                           unless we are in debugging mode. */
+                        /*
+                         * Got connection.  Fork a child to handle it, unless
+                         * we are in debugging mode.
+                         */
                         if (debug_flag) {
-                                /* In debugging mode.  Close the listening
-                                   socket, and start processing the
-                                   connection without forking. */
+                                /*
+                                 * In debugging mode.  Close the listening
+                                 * socket, and start processing the
+                                 * connection without forking.
+                                 */
                                 debug("Server will not fork when running in debugging mode.");
                                 close(listen_sock);
                                 sock_in = newsock;
@@ -695,16 +708,17 @@ main(int ac, char **av)
                                 pid = getpid();
                                 break;
                         } else {
-                                /* Normal production daemon.  Fork, and
-                                   have the child process the connection.
-                                   The parent continues listening. */
+                                /*
+                                 * Normal production daemon.  Fork, and have
+                                 * the child process the connection. The
+                                 * parent continues listening.
+                                 */
                                 if ((pid = fork()) == 0) {
-                                        /* Child.  Close the listening
-                                           socket, and start using the
-                                           accepted socket.  Reinitialize
-                                           logging (since our pid has
-                                           changed).  We break out of the
-                                           loop to handle the connection. */
+                                        /*
+                                         * Child.  Close the listening socket, and start using the
+                                         * accepted socket.  Reinitialize logging (since our pid has
+                                         * changed).  We break out of the loop to handle the connection.
+                                         */
                                         close(listen_sock);
                                         sock_in = newsock;
                                         sock_out = newsock;
@@ -731,9 +745,11 @@ main(int ac, char **av)
 
         /* This is the child processing a new connection. */
 
-        /* Disable the key regeneration alarm.  We will not regenerate the
-           key since we are no longer in a position to give it to anyone.
-           We will not restart on SIGHUP since it no longer makes sense. */
+        /*
+         * Disable the key regeneration alarm.  We will not regenerate the
+         * key since we are no longer in a position to give it to anyone. We
+         * will not restart on SIGHUP since it no longer makes sense.
+         */
         alarm(0);
         signal(SIGALRM, SIG_DFL);
         signal(SIGHUP, SIG_DFL);
@@ -741,17 +757,20 @@ main(int ac, char **av)
         signal(SIGQUIT, SIG_DFL);
         signal(SIGCHLD, SIG_DFL);
 
-        /* Set socket options for the connection.  We want the socket to
-           close as fast as possible without waiting for anything.  If the
-           connection is not a socket, these will do nothing. */
-        /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on,
-           sizeof(on)); */
+        /*
+         * Set socket options for the connection.  We want the socket to
+         * close as fast as possible without waiting for anything.  If the
+         * connection is not a socket, these will do nothing.
+         */
+        /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
         linger.l_onoff = 1;
         linger.l_linger = 5;
         setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
 
-        /* Register our connection.  This turns encryption off because we
-           do not have a key. */
+        /*
+         * Register our connection.  This turns encryption off because we do
+         * not have a key.
+         */
         packet_set_connection(sock_in, sock_out);
 
         remote_port = get_remote_port();
@@ -777,12 +796,14 @@ main(int ac, char **av)
         verbose("Connection from %.500s port %d", remote_ip, remote_port);
 #endif /* LIBWRAP */
 
-        /* We don\'t want to listen forever unless the other side
-           successfully authenticates itself.  So we set up an alarm which
-           is cleared after successful authentication.  A limit of zero
-           indicates no limit. Note that we don\'t set the alarm in
-           debugging mode; it is just annoying to have the server exit
-           just when you are about to discover the bug. */
+        /*
+         * We don\'t want to listen forever unless the other side
+         * successfully authenticates itself.  So we set up an alarm which is
+         * cleared after successful authentication.  A limit of zero
+         * indicates no limit. Note that we don\'t set the alarm in debugging
+         * mode; it is just annoying to have the server exit just when you
+         * are about to discover the bug.
+         */
         signal(SIGALRM, grace_alarm_handler);
         if (!debug_flag)
                 alarm(options.login_grace_time);
@@ -815,8 +836,10 @@ main(int ac, char **av)
                 buf[sizeof(buf) - 1] = 0;
         }
 
-        /* Check that the versions match.  In future this might accept
-           several versions and set appropriate flags to handle them. */
+        /*
+         * Check that the versions match.  In future this might accept
+         * several versions and set appropriate flags to handle them.
+         */
         if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor,
                    remote_version) != 3) {
                 const char *s = "Protocol mismatch.\n";
@@ -848,11 +871,13 @@ main(int ac, char **av)
                         no_agent_forwarding_flag = 1;
                 }
         }
-        /* Check that the connection comes from a privileged port.  Rhosts-
-           and Rhosts-RSA-Authentication only make sense from priviledged
-           programs.  Of course, if the intruder has root access on his
-           local machine, he can connect from any port.  So do not use
-           these authentication methods from machines that you do not trust. */
+        /*
+         * Check that the connection comes from a privileged port.  Rhosts-
+         * and Rhosts-RSA-Authentication only make sense from priviledged
+         * programs.  Of course, if the intruder has root access on his local
+         * machine, he can connect from any port.  So do not use these
+         * authentication methods from machines that you do not trust.
+         */
         if (remote_port >= IPPORT_RESERVED ||
             remote_port < IPPORT_RESERVED / 2) {
                 options.rhosts_authentication = 0;
@@ -914,13 +939,15 @@ do_connection()
         int plen, slen;
         u_int32_t rand = 0;
 
-        /* Generate check bytes that the client must send back in the user
-           packet in order for it to be accepted; this is used to defy ip
-           spoofing attacks.  Note that this only works against somebody
-           doing IP spoofing from a remote machine; any machine on the
-           local network can still see outgoing packets and catch the
-           random cookie.  This only affects rhosts authentication, and
-           this is one of the reasons why it is inherently insecure. */
+        /*
+         * Generate check bytes that the client must send back in the user
+         * packet in order for it to be accepted; this is used to defy ip
+         * spoofing attacks.  Note that this only works against somebody
+         * doing IP spoofing from a remote machine; any machine on the local
+         * network can still see outgoing packets and catch the random
+         * cookie.  This only affects rhosts authentication, and this is one
+         * of the reasons why it is inherently insecure.
+         */
         for (i = 0; i < 8; i++) {
                 if (i % 4 == 0)
                         rand = arc4random();
@@ -928,9 +955,11 @@ do_connection()
                 rand >>= 8;
         }
 
-        /* Send our public key.  We include in the packet 64 bits of
-           random data that must be matched in the reply in order to
-           prevent IP spoofing. */
+        /*
+         * Send our public key.  We include in the packet 64 bits of random
+         * data that must be matched in the reply in order to prevent IP
+         * spoofing.
+         */
         packet_start(SSH_SMSG_PUBLIC_KEY);
         for (i = 0; i < 8; i++)
                 packet_put_char(check_bytes[i]);
@@ -1002,14 +1031,15 @@ do_connection()
         session_key_int = BN_new();
         packet_get_bignum(session_key_int, &slen);
 
-        /* Get protocol flags. */
         protocol_flags = packet_get_int();
         packet_set_protocol_flags(protocol_flags);
 
         packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
 
-        /* Decrypt it using our private server key and private host key
-           (key with larger modulus first). */
+        /*
+         * Decrypt it using our private server key and private host key (key
+         * with larger modulus first).
+         */
         if (BN_cmp(sensitive_data.private_key->n, sensitive_data.host_key->n) > 0) {
                 /* Private key has bigger modulus. */
                 if (BN_num_bits(sensitive_data.private_key->n) <
@@ -1040,14 +1070,15 @@ do_connection()
                                     sensitive_data.private_key);
         }
 
-        /* Compute session id for this session. */
         compute_session_id(session_id, check_bytes,
                            sensitive_data.host_key->n,
                            sensitive_data.private_key->n);
 
-        /* Extract session key from the decrypted integer.  The key is in
-           the least significant 256 bits of the integer; the first byte
-           of the key is in the highest bits. */
+        /*
+         * Extract session key from the decrypted integer.  The key is in the
+         * least significant 256 bits of the integer; the first byte of the
+         * key is in the highest bits.
+         */
         BN_mask_bits(session_key_int, sizeof(session_key) * 8);
         len = BN_num_bytes(session_key_int);
         if (len < 0 || len > sizeof(session_key))
@@ -1125,8 +1156,7 @@ allowed_user(struct passwd * pw)
                         if (match_pattern(pw->pw_name, options.deny_users[i]))
                                 return 0;
         }
-        /* Return false if AllowUsers isn't empty and user isn't listed
-           there */
+        /* Return false if AllowUsers isn't empty and user isn't listed there */
         if (options.num_allow_users > 0) {
                 if (!pw->pw_name)
                         return 0;
@@ -1151,8 +1181,10 @@ allowed_user(struct passwd * pw)
                                 if (match_pattern(grp->gr_name, options.deny_groups[i]))
                                         return 0;
                 }
-                /* Return false if AllowGroups isn't empty and user's
-                   group isn't listed there */
+                /*
+                 * Return false if AllowGroups isn't empty and user's group
+                 * isn't listed there
+                 */
                 if (options.num_allow_groups > 0) {
                         if (!grp->gr_name)
                                 return 0;
@@ -1216,8 +1248,10 @@ do_authentication(char *user)
         }
 #endif
 
-        /* If we are not running as root, the user must have the same uid
-           as the server. */
+        /*
+         * If we are not running as root, the user must have the same uid as
+         * the server.
+         */
         if (getuid() != 0 && pw->pw_uid != getuid())
                 packet_disconnect("Cannot change user when server not running as root.");
 
@@ -1357,10 +1391,12 @@ do_authloop(struct passwd * pw)
                                 verbose("Rhosts authentication disabled.");
                                 break;
                         }
-                        /* Get client user name.  Note that we just have
-                           to trust the client; this is one reason why
-                           rhosts authentication is insecure. (Another is
-                           IP-spoofing on a local network.) */
+                        /*
+                         * Get client user name.  Note that we just have to
+                         * trust the client; this is one reason why rhosts
+                         * authentication is insecure. (Another is
+                         * IP-spoofing on a local network.)
+                         */
                         client_user = packet_get_string(&ulen);
                         packet_integrity_check(plen, 4 + ulen, type);
 
@@ -1379,9 +1415,11 @@ do_authloop(struct passwd * pw)
                                 verbose("Rhosts with RSA authentication disabled.");
                                 break;
                         }
-                        /* Get client user name.  Note that we just have
-                           to trust the client; root on the client machine
-                           can claim to be any user. */
+                        /*
+                         * Get client user name.  Note that we just have to
+                         * trust the client; root on the client machine can
+                         * claim to be any user.
+                         */
                         client_user = packet_get_string(&ulen);
 
                         /* Get the client host key. */
@@ -1425,9 +1463,11 @@ do_authloop(struct passwd * pw)
                                 verbose("Password authentication disabled.");
                                 break;
                         }
-                        /* Read user password.  It is in plain text, but
-                           was transmitted over the encrypted channel so
-                           it is not visible to an outside observer. */
+                        /*
+                         * Read user password.  It is in plain text, but was
+                         * transmitted over the encrypted channel so it is
+                         * not visible to an outside observer.
+                         */
                         password = packet_get_string(&dlen);
                         packet_integrity_check(plen, 4 + dlen, type);
 
@@ -1463,8 +1503,7 @@ do_authloop(struct passwd * pw)
                                         skeyinfo = skey_fake_keyinfo(pw->pw_name);
                                 }
                                 if (skeyinfo != NULL) {
-                                        /* we send our s/key- in
-                                           tis-challenge messages */
+                                        /* we send our s/key- in tis-challenge messages */
                                         debug("sending challenge '%s'", skeyinfo);
                                         packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
                                         packet_put_string(skeyinfo, strlen(skeyinfo));
@@ -1493,8 +1532,10 @@ do_authloop(struct passwd * pw)
 #endif
 
                 default:
-                        /* Any unknown messages will be ignored (and
-                           failure returned) during authentication. */
+                        /*
+                         * Any unknown messages will be ignored (and failure
+                         * returned) during authentication.
+                         */
                         log("Unknown message during authentication: type %d", type);
                         break;
                 }
@@ -1559,11 +1600,12 @@ do_fake_authloop(char *user)
         packet_send();
         packet_write_wait();
 
-        /* Keep reading packets, and always respond with a failure.  This
-           is to avoid disclosing whether such a user really exists. */
+        /*
+         * Keep reading packets, and always respond with a failure.  This is
+         * to avoid disclosing whether such a user really exists.
+         */
         for (attempt = 1;; attempt++) {
-                /* Read a packet.  This will not return if the client
-                   disconnects. */
+                /* Read a packet.  This will not return if the client disconnects. */
                 int plen;
                 int type = packet_read(&plen);
 #ifdef SKEY
@@ -1583,8 +1625,10 @@ do_fake_authloop(char *user)
                 if (attempt > AUTH_FAIL_MAX)
                         packet_disconnect(AUTH_FAIL_MSG, user);
 
-                /* Send failure.  This should be indistinguishable from a
-                   failed authentication. */
+                /*
+                 * Send failure.  This should be indistinguishable from a
+                 * failed authentication.
+                 */
                 packet_start(SSH_SMSG_FAILURE);
                 packet_send();
                 packet_write_wait();
@@ -1630,19 +1674,25 @@ do_authenticated(struct passwd * pw)
         mode_t tty_mode;
         int n_bytes;
 
-        /* Cancel the alarm we set to limit the time taken for
-           authentication. */
+        /*
+         * Cancel the alarm we set to limit the time taken for
+         * authentication.
+         */
         alarm(0);
 
-        /* Inform the channel mechanism that we are the server side and
-           that the client may request to connect to any port at all.
-           (The user could do it anyway, and we wouldn\'t know what is
-           permitted except by the client telling us, so we can equally
-           well trust the client not to request anything bogus.) */
+        /*
+         * Inform the channel mechanism that we are the server side and that
+         * the client may request to connect to any port at all. (The user
+         * could do it anyway, and we wouldn\'t know what is permitted except
+         * by the client telling us, so we can equally well trust the client
+         * not to request anything bogus.)
+         */
         channel_permit_all_opens();
 
-        /* We stay in this loop until the client requests to execute a
-           shell or a command. */
+        /*
+         * We stay in this loop until the client requests to execute a shell
+         * or a command.
+         */
         while (1) {
                 int plen, dlen;
 
@@ -1826,8 +1876,10 @@ do_authenticated(struct passwd * pw)
                         return;
 
                 default:
-                        /* Any unknown messages in this phase are ignored,
-                           and a failure message is returned. */
+                        /*
+                         * Any unknown messages in this phase are ignored,
+                         * and a failure message is returned.
+                         */
                         log("Unknown packet type received after authentication: %d", type);
                         goto fail;
                 }
@@ -1852,8 +1904,10 @@ fail:
                 continue;
 
 do_forced_command:
-                /* There is a forced command specified for this login.
-                   Execute it. */
+                /*
+                 * There is a forced command specified for this login.
+                 * Execute it.
+                 */
                 debug("Executing forced command: %.900s", forced_command);
                 if (have_pty)
                         do_exec_pty(forced_command, ptyfd, ttyfd, ttyname, pw, term, display, proto, data);
@@ -1897,14 +1951,18 @@ do_exec_no_pty(const char *command, struct passwd * pw,
                 /* Child.  Reinitialize the log since the pid has changed. */
                 log_init(av0, options.log_level, options.log_facility, log_stderr);
 
-                /* Create a new session and process group since the 4.4BSD
-                   setlogin() affects the entire process group. */
+                /*
+                 * Create a new session and process group since the 4.4BSD
+                 * setlogin() affects the entire process group.
+                 */
                 if (setsid() < 0)
                         error("setsid failed: %.100s", strerror(errno));
 
 #ifdef USE_PIPES
-                /* Redirect stdin.  We close the parent side of the socket
-                   pair, and make the child side the standard input. */
+                /*
+                 * Redirect stdin.  We close the parent side of the socket
+                 * pair, and make the child side the standard input.
+                 */
                 close(pin[1]);
                 if (dup2(pin[0], 0) < 0)
                         perror("dup2 stdin");
@@ -1922,9 +1980,11 @@ do_exec_no_pty(const char *command, struct passwd * pw,
                         perror("dup2 stderr");
                 close(perr[1]);
 #else /* USE_PIPES */
-                /* Redirect stdin, stdout, and stderr.  Stdin and stdout
-                   will use the same socket, as some programs
-                   (particularly rdist) seem to depend on it. */
+                /*
+                 * Redirect stdin, stdout, and stderr.  Stdin and stdout will
+                 * use the same socket, as some programs (particularly rdist)
+                 * seem to depend on it.
+                 */
                 close(inout[1]);
                 close(err[1]);
                 if (dup2(inout[0], 0) < 0)      /* stdin */
@@ -1955,8 +2015,10 @@ do_exec_no_pty(const char *command, struct passwd * pw,
         close(inout[0]);
         close(err[0]);
 
-        /* Enter the interactive session.  Note: server_loop must be able
-           to handle the case that fdin and fdout are the same. */
+        /*
+         * Enter the interactive session.  Note: server_loop must be able to
+         * handle the case that fdin and fdout are the same.
+         */
         server_loop(pid, inout[1], inout[1], err[1]);
         /* server_loop has closed inout[1] and err[1]. */
 #endif /* USE_PIPES */
@@ -2012,8 +2074,10 @@ do_exec_pty(const char *command, int ptyfd, int ttyfd,
         /* Get remote host name. */
         hostname = get_canonical_hostname();
 
-        /* Get the time when the user last logged in.  Buf will be set to
-           contain the hostname the last login was from. */
+        /*
+         * Get the time when the user last logged in.  Buf will be set to
+         * contain the hostname the last login was from.
+         */
         if (!options.use_login) {
                 last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name,
                                                       buf, sizeof(buf));
@@ -2049,9 +2113,11 @@ do_exec_pty(const char *command, int ptyfd, int ttyfd,
                 /* Close the extra descriptor for the pseudo tty. */
                 close(ttyfd);
 
-                /* Get IP address of client.  This is needed because we
-                   want to record where the user logged in from.  If the
-                   connection is not a socket, let the ip address be 0.0.0.0. */
+                /*
+                 * Get IP address of client.  This is needed because we want
+                 * to record where the user logged in from.  If the
+                 * connection is not a socket, let the ip address be 0.0.0.0.
+                 */
                 memset(&from, 0, sizeof(from));
                 if (packet_get_connection_in() == packet_get_connection_out()) {
                         fromlen = sizeof(from);
@@ -2075,12 +2141,14 @@ do_exec_pty(const char *command, int ptyfd, int ttyfd,
                         fprintf(stderr, pamconv_msg);
 #endif
 
-                /* If the user has logged in before, display the time of
-                   last login. However, don't display anything extra if a
-                   command has been specified (so that ssh can be used to
-                   execute commands on a remote machine without users
-                   knowing they are going to another machine). Login(1)
-                   will do this for us as well, so check if login(1) is used */
+                /*
+                 * If the user has logged in before, display the time of last
+                 * login. However, don't display anything extra if a command
+                 * has been specified (so that ssh can be used to execute
+                 * commands on a remote machine without users knowing they
+                 * are going to another machine). Login(1) will do this for
+                 * us as well, so check if login(1) is used
+                 */
                 if (command == NULL && last_login_time != 0 && !quiet_login &&
                     !options.use_login) {
                         /* Convert the date to a string. */
@@ -2095,10 +2163,12 @@ do_exec_pty(const char *command, int ptyfd, int ttyfd,
                         else
                                 printf("Last login: %s from %s\r\n", time_string, buf);
                 }
-                /* Print /etc/motd unless a command was specified or
-                   printing it was disabled in server options or login(1)
-                   will be used.  Note that some machines appear to print
-                   it in /etc/profile or similar. */
+                /*
+                 * Print /etc/motd unless a command was specified or printing
+                 * it was disabled in server options or login(1) will be
+                 * used.  Note that some machines appear to print it in
+                 * /etc/profile or similar.
+                 */
                 if (command == NULL && options.print_motd && !quiet_login &&
                     !options.use_login) {
                         /* Print /etc/motd if it exists. */
@@ -2118,15 +2188,19 @@ do_exec_pty(const char *command, int ptyfd, int ttyfd,
         /* Parent.  Close the slave side of the pseudo tty. */
         close(ttyfd);
 
-        /* Create another descriptor of the pty master side for use as the
-           standard input.  We could use the original descriptor, but this
-           simplifies code in server_loop.  The descriptor is bidirectional. */
+        /*
+         * Create another descriptor of the pty master side for use as the
+         * standard input.  We could use the original descriptor, but this
+         * simplifies code in server_loop.  The descriptor is bidirectional.
+         */
         fdout = dup(ptyfd);
         if (fdout < 0)
                 packet_disconnect("dup failed: %.100s", strerror(errno));
 
-        /* Add a cleanup function to clear the utmp entry and record logout
-           time in case we call fatal() (e.g., the connection gets closed). */
+        /*
+         * Add a cleanup function to clear the utmp entry and record logout
+         * time in case we call fatal() (e.g., the connection gets closed).
+         */
         cleanup_context.pid = pid;
         cleanup_context.ttyname = ttyname;
         fatal_add_cleanup(pty_cleanup_proc, (void *) &cleanup_context);
@@ -2144,9 +2218,11 @@ do_exec_pty(const char *command, int ptyfd, int ttyfd,
         /* Release the pseudo-tty. */
         pty_release(ttyname);
 
-        /* Close the server side of the socket pairs.  We must do this
-           after the pty cleanup, so that another process doesn't get this
-           pty while we're still cleaning up. */
+        /*
+         * Close the server side of the socket pairs.  We must do this after
+         * the pty cleanup, so that another process doesn't get this pty
+         * while we're still cleaning up.
+         */
         close(ptyfd);
         close(fdout);
 }
@@ -2162,19 +2238,21 @@ child_set_env(char ***envp, unsigned int *envsizep, const char *name,
         unsigned int i, namelen;
         char **env;
 
-        /* Find the slot where the value should be stored.  If the
-           variable already exists, we reuse the slot; otherwise we append
-           a new slot at the end of the array, expanding if necessary. */
+        /*
+         * Find the slot where the value should be stored.  If the variable
+         * already exists, we reuse the slot; otherwise we append a new slot
+         * at the end of the array, expanding if necessary.
+         */
         env = *envp;
         namelen = strlen(name);
         for (i = 0; env[i]; i++)
                 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
                         break;
         if (env[i]) {
-                /* Name already exists.  Reuse the slot. */
+                /* Reuse the slot. */
                 xfree(env[i]);
         } else {
-                /* New variable.  Expand the array if necessary. */
+                /* New variable.  Expand if necessary. */
                 if (i >= (*envsizep) - 1) {
                         (*envsizep) += 50;
                         env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *));
@@ -2202,40 +2280,27 @@ read_environment_file(char ***env, unsigned int *envsize,
         char buf[4096];
         char *cp, *value;
 
-        /* Open the environment file. */
         f = fopen(filename, "r");
         if (!f)
                 return;
 
-        /* Process each line. */
         while (fgets(buf, sizeof(buf), f)) {
-                /* Skip leading whitespace. */
-                for (cp = buf; *cp == ' ' || *cp == '\t'; cp++);
-
-                /* Ignore empty and comment lines. */
+                for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
+                        ;
                 if (!*cp || *cp == '#' || *cp == '\n')
                         continue;
-
-                /* Remove newline. */
                 if (strchr(cp, '\n'))
                         *strchr(cp, '\n') = '\0';
-
-                /* Find the equals sign.  Its lack indicates badly
-                   formatted line. */
                 value = strchr(cp, '=');
                 if (value == NULL) {
                         fprintf(stderr, "Bad line in %.100s: %.200s\n", filename, buf);
                         continue;
                 }
-                /* Replace the equals sign by nul, and advance value to
-                   the value string. */
+                /* Replace the equals sign by nul, and advance value to the value string. */
                 *value = '\0';
                 value++;
-
-                /* Set the value in environment. */
                 child_set_env(env, envsize, cp, value);
         }
-
         fclose(f);
 }
 
@@ -2299,8 +2364,10 @@ do_child(const char *command, struct passwd * pw, const char *term,
                 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
                         fatal("Failed to set uids to %d.", (int) pw->pw_uid);
         }
-        /* Get the shell from the password data.  An empty shell field is
-           legal, and means /bin/sh. */
+        /*
+         * Get the shell from the password data.  An empty shell field is
+         * legal, and means /bin/sh.
+         */
         shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
 
 #ifdef AFS
@@ -2315,8 +2382,7 @@ do_child(const char *command, struct passwd * pw, const char *term,
         }
 #endif /* AFS */
 
-        /* Initialize the environment.  In the first part we allocate
-           space for all environment variables. */
+        /* Initialize the environment. */
         envsize = 100;
         env = xmalloc(envsize * sizeof(char *));
         env[0] = NULL;
@@ -2335,7 +2401,6 @@ do_child(const char *command, struct passwd * pw, const char *term,
                 /* Normal systems set SHELL by default. */
                 child_set_env(&env, &envsize, "SHELL", shell);
         }
-        /* Let it inherit timezone if we have one. */
         if (getenv("TZ"))
                 child_set_env(&env, &envsize, "TZ", getenv("TZ"));
 
@@ -2354,20 +2419,14 @@ do_child(const char *command, struct passwd * pw, const char *term,
                 xfree(ce);
         }
 
-        /* Set SSH_CLIENT. */
         snprintf(buf, sizeof buf, "%.50s %d %d",
                  get_remote_ipaddr(), get_remote_port(), options.port);
         child_set_env(&env, &envsize, "SSH_CLIENT", buf);
 
-        /* Set SSH_TTY if we have a pty. */
         if (ttyname)
                 child_set_env(&env, &envsize, "SSH_TTY", ttyname);
-
-        /* Set TERM if we have a pty. */
         if (term)
                 child_set_env(&env, &envsize, "TERM", term);
-
-        /* Set DISPLAY if we have one. */
         if (display)
                 child_set_env(&env, &envsize, "DISPLAY", display);
 
@@ -2400,52 +2459,57 @@ do_child(const char *command, struct passwd * pw, const char *term,
         }
 #endif /* HAVE_LIBPAM */
 
-        /* Set XAUTHORITY to always be a local file. */
         if (xauthfile)
                 child_set_env(&env, &envsize, "XAUTHORITY", xauthfile);
 
-        /* Set variable for forwarded authentication connection, if we
-           have one. */
         if (auth_get_socket_name() != NULL)
                 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
                               auth_get_socket_name());
 
-        /* Read $HOME/.ssh/environment. */
+        /* read $HOME/.ssh/environment. */
         if (!options.use_login) {
                 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", pw->pw_dir);
                 read_environment_file(&env, &envsize, buf);
         }
-        /* If debugging, dump the environment to stderr. */
         if (debug_flag) {
+                /* dump the environment */
                 fprintf(stderr, "Environment:\n");
                 for (i = 0; env[i]; i++)
                         fprintf(stderr, "  %.200s\n", env[i]);
         }
-        /* Close the connection descriptors; note that this is the child,
-           and the server will still have the socket open, and it is
-           important that we do not shutdown it.  Note that the
-           descriptors cannot be closed before building the environment,
-           as we call get_remote_ipaddr there. */
+        /*
+         * Close the connection descriptors; note that this is the child, and
+         * the server will still have the socket open, and it is important
+         * that we do not shutdown it.  Note that the descriptors cannot be
+         * closed before building the environment, as we call
+         * get_remote_ipaddr there.
+         */
         if (packet_get_connection_in() == packet_get_connection_out())
                 close(packet_get_connection_in());
         else {
                 close(packet_get_connection_in());
                 close(packet_get_connection_out());
         }
-        /* Close all descriptors related to channels.  They will still
-           remain open in the parent. */
+        /*
+         * Close all descriptors related to channels.  They will still remain
+         * open in the parent.
+         */
+        /* XXX better use close-on-exec? -markus */
         channel_close_all();
 
-        /* Close any extra file descriptors.  Note that there may still be
-           descriptors left by system functions.  They will be closed
-           later. */
+        /*
+         * Close any extra file descriptors.  Note that there may still be
+         * descriptors left by system functions.  They will be closed later.
+         */
         endpwent();
         endhostent();
 
-        /* Close any extra open file descriptors so that we don\'t have
-           them hanging around in clients.  Note that we want to do this
-           after initgroups, because at least on Solaris 2.3 it leaves
-           file descriptors open. */
+        /*
+         * Close any extra open file descriptors so that we don\'t have them
+         * hanging around in clients.  Note that we want to do this after
+         * initgroups, because at least on Solaris 2.3 it leaves file
+         * descriptors open.
+         */
         for (i = 3; i < 64; i++)
                 close(i);
 
@@ -2454,12 +2518,16 @@ do_child(const char *command, struct passwd * pw, const char *term,
                 fprintf(stderr, "Could not chdir to home directory %s: %s\n",
                         pw->pw_dir, strerror(errno));
 
-        /* Must take new environment into use so that .ssh/rc, /etc/sshrc
-           and xauth are run in the proper environment. */
+        /*
+         * Must take new environment into use so that .ssh/rc, /etc/sshrc and
+         * xauth are run in the proper environment.
+         */
         environ = env;
 
-        /* Run $HOME/.ssh/rc, /etc/sshrc, or xauth (whichever is found
-           first in this order). */
+        /*
+         * Run $HOME/.ssh/rc, /etc/sshrc, or xauth (whichever is found first
+         * in this order).
+         */
         if (!options.use_login) {
                 if (stat(SSH_USER_RC, &st) >= 0) {
                         if (debug_flag)
@@ -2486,8 +2554,7 @@ do_child(const char *command, struct passwd * pw, const char *term,
                 }
 #ifdef XAUTH_PATH
                 else {
-                        /* Add authority data to .Xauthority if
-                           appropriate. */
+                        /* Add authority data to .Xauthority if appropriate. */
                         if (auth_proto != NULL && auth_data != NULL) {
                                 if (debug_flag)
                                         fprintf(stderr, "Running %.100s add %.100s %.100s %.100s\n",
@@ -2510,15 +2577,19 @@ do_child(const char *command, struct passwd * pw, const char *term,
                 else
                         cp = shell;
         }
-        /* If we have no command, execute the shell.  In this case, the
-           shell name to be passed in argv[0] is preceded by '-' to
-           indicate that this is a login shell. */
+        /*
+         * If we have no command, execute the shell.  In this case, the shell
+         * name to be passed in argv[0] is preceded by '-' to indicate that
+         * this is a login shell.
+         */
         if (!command) {
                 if (!options.use_login) {
                         char buf[256];
 
-                        /* Check for mail if we have a tty and it was
-                           enabled in server options. */
+                        /*
+                         * Check for mail if we have a tty and it was enabled
+                         * in server options.
+                         */
                         if (ttyname && options.check_mail) {
                                 char *mailbox;
                                 struct stat mailstat;
@@ -2558,8 +2629,10 @@ do_child(const char *command, struct passwd * pw, const char *term,
                         exit(1);
                 }
         }
-        /* Execute the command using the user's shell.  This uses the -c
-           option to execute the command. */
+        /*
+         * Execute the command using the user's shell.  This uses the -c
+         * option to execute the command.
+         */
         argv[0] = (char *) cp;
         argv[1] = "-c";
         argv[2] = (char *) command;