/*
* pptp_handle_ctrl_connection
*
* 1. read a packet (should be start_ctrl_conn_rqst)
* 2. reply to packet (send a start_ctrl_conn_rply)
* 3. proceed with GRE and CTRL connections
*
* args: pppaddrs - ppp local and remote addresses (strings)
* inetaddrs - local and client socket address
* retn: 0 success, -1 failure
*/
static void pptp_handle_ctrl_connection(char **pppaddrs, struct in_addr *inetaddrs)
{
/* For echo requests used to check link is alive */
int echo_wait = FALSE; /* Waiting for echo? */
u_int32_t echo_count = 0; /* Sequence # of echo */
time_t echo_time = 0; /* Time last echo req sent */
struct timeval idleTime; /* How long to select() */
/* General local variables */
ssize_t rply_size; /* Reply packet size */
fd_set fds; /* For select() */
int maxfd = clientSocket; /* For select() */
int send_packet; /* Send a packet this time? */
#if BSDUSER_PPP || SLIRP
/* not needed by stuff which uses socketpair() in startCall() */
#define init 1
#else
int init = 0; /* Has pppd initialized the pty? */
#endif
int pty_fd = -1; /* File descriptor of pty */
int gre_fd = -1; /* Network file descriptor */
int sig_fd = sigpipe_fd(); /* Signal pipe descriptor */
unsigned char packet[PPTP_MAX_CTRL_PCKT_SIZE];
unsigned char rply_packet[PPTP_MAX_CTRL_PCKT_SIZE];
for (;;) {
FD_ZERO(&fds);
FD_SET(sig_fd, &fds);
FD_SET(clientSocket, &fds);
if (pty_fd != -1)
FD_SET(pty_fd, &fds);
if (gre_fd != -1 && init)
FD_SET(gre_fd, &fds);
/* set timeout */
if (encaps_gre(-1, NULL, 0) || decaps_hdlc(-1, NULL, 0)) {
idleTime.tv_sec = 0;
idleTime.tv_usec = 50000; /* don't ack immediately */
} else {
idleTime.tv_sec = IDLE_WAIT;
idleTime.tv_usec = 0;
}
/* default: do nothing */
send_packet = FALSE;
switch (select(maxfd + 1, &fds, NULL, NULL, &idleTime)) {
case -1: /* Error with select() */
if (errno != EINTR)
syslog(LOG_ERR, "CTRL: Error with select(), quitting");
goto leave_clear_call;
case 0:
if (decaps_hdlc(-1, NULL, 0)) {
if(decaps_hdlc(-1, encaps_gre, gre_fd))
syslog(LOG_ERR, "CTRL: GRE re-xmit failed");
} else if (encaps_gre(-1, NULL, 0))
/* Pending ack and nothing else to do */
encaps_gre(gre_fd, NULL, 0); /* send ack with no payload */
else if (echo_wait != TRUE) {
/* Timeout. Start idle link detection. */
echo_count++;
if (pptpctrl_debug)
syslog(LOG_DEBUG, "CTRL: Sending ECHO REQ id %d", echo_count);
time(&echo_time);
make_echo_req_packet(rply_packet, &rply_size, echo_count);
echo_wait = TRUE;
send_packet = TRUE;
}
break;
default:
break;
}
/* check for pending SIGTERM delivery */
if (FD_ISSET(sig_fd, &fds)) {
if (sigpipe_read() == SIGTERM)
bail(SIGTERM);
}
/* detect startup of pppd */
#ifndef init
if (!init && pty_fd != -1 && FD_ISSET(pty_fd, &fds))
init = 1;
#endif
/* handle actual packets */
/* send from pty off via GRE */
if (pty_fd != -1 && FD_ISSET(pty_fd, &fds) && decaps_hdlc(pty_fd, encaps_gre, gre_fd) < 0) {
syslog(LOG_ERR, "CTRL: PTY read or GRE write failed (pty,gre)=(%d,%d)", pty_fd, gre_fd);
break;
}
/* send from GRE off to pty */
if (gre_fd != -1 && FD_ISSET(gre_fd, &fds) && decaps_gre(gre_fd, encaps_hdlc, pty_fd) < 0) {
if (gre_fd == 6 && pty_fd == 5) {
syslog(LOG_ERR, "CTRL: GRE-tunnel has collapsed (GRE read or PTY write failed (gre,pty)=(%d,%d))", gre_fd, pty_fd);
} else {
syslog(LOG_ERR, "CTRL: GRE read or PTY write failed (gre,pty)=(%d,%d)", gre_fd, pty_fd);
}
break;
}
/* handle control messages */
if (FD_ISSET(clientSocket, &fds)) {
send_packet = TRUE;
switch (read_pptp_packet(clientSocket, packet, rply_packet, &rply_size)) {
case 0:
syslog(LOG_ERR, "CTRL: CTRL read failed");
goto leave_drop_call;
case -1:
send_packet = FALSE;
break;
case STOP_CTRL_CONN_RQST:
if (pptpctrl_debug)
syslog(LOG_DEBUG, "CTRL: Received STOP CTRL CONN request (disconnecting)");
if (gre_fd != -1 || pty_fd != -1)
syslog(LOG_WARNING, "CTRL: Request to close control connection when call is open, closing");
send_pptp_packet(clientSocket, rply_packet, rply_size);
goto leave_drop_call;
case CALL_CLR_RQST:
if(pptpctrl_debug)
syslog(LOG_DEBUG, "CTRL: Received CALL CLR request (closing call)");
if (gre_fd == -1 || pty_fd == -1)
syslog(LOG_WARNING, "CTRL: Request to close call but call not open");
if (gre_fd != -1) {
FD_CLR(gre_fd, &fds);
close(gre_fd);
gre_fd = -1;
}
if (pty_fd != -1) {
FD_CLR(pty_fd, &fds);
close(pty_fd);
pty_fd = -1;
}
/* violating RFC */
goto leave_drop_call;
case OUT_CALL_RQST:
/* for killing off the link later (ugly) */
NOTE_VALUE(PAC, call_id_pair, ((struct pptp_out_call_rply *) (rply_packet))->call_id);
NOTE_VALUE(PNS, call_id_pair, ((struct pptp_out_call_rply *) (rply_packet))->call_id_peer);
if (gre_fd != -1 || pty_fd != -1) {
syslog(LOG_WARNING, "CTRL: Request to open call when call is already open, closing");
if (gre_fd != -1) {
FD_CLR(gre_fd, &fds);
close(gre_fd);
gre_fd = -1;
}
if (pty_fd != -1) {
FD_CLR(pty_fd, &fds);
close(pty_fd);
pty_fd = -1;
}
}
/* change process title for accounting and status scripts */
my_setproctitle(gargc, gargv,
"pptpd [%s:%04X - %04X]",
inet_ntoa(inetaddrs[1]),
ntohs(((struct pptp_out_call_rply *) (rply_packet))->call_id_peer),
ntohs(((struct pptp_out_call_rply *) (rply_packet))->call_id));
/* start the call, by launching pppd */
syslog(LOG_INFO, "CTRL: Starting call (launching pppd, opening GRE)");
pty_fd = startCall(pppaddrs, inetaddrs);
if (pty_fd > maxfd) maxfd = pty_fd;
if ((gre_fd = pptp_gre_init(call_id_pair, pty_fd, inetaddrs)) > maxfd)
maxfd = gre_fd;
break;
case ECHO_RPLY:
if (echo_wait == TRUE && ((struct pptp_echo_rply *) (packet))->identifier == echo_count)
echo_wait = FALSE;
else
syslog(LOG_WARNING, "CTRL: Unexpected ECHO REPLY packet");
/* FALLTHRU */
case SET_LINK_INFO:
send_packet = FALSE;
break;
#ifdef PNS_MODE
case IN_CALL_RQST:
case IN_CALL_RPLY:
case IN_CALL_CONN:
#endif
case CALL_DISCONN_NTFY:
case STOP_CTRL_CONN_RPLY:
/* These don't generate replies. Also they come from things we don't send in this section. */
syslog(LOG_WARNING, "CTRL: Got a reply to a packet we didn't send");
send_packet = FALSE;
break;
/* Otherwise, the already-formed reply will do fine, so send it */
}
}
/* send reply packet - this may block, but it should be very rare */
if (send_packet == TRUE && send_pptp_packet(clientSocket, rply_packet, rply_size) < 0) {
syslog(LOG_ERR, "CTRL: Error sending GRE, aborting call");
goto leave_clear_call;
}
/* waiting for echo reply and curtime - echo_time > max wait */
if (echo_wait == TRUE && (time(NULL) - echo_time) > MAX_ECHO_WAIT) {
syslog(LOG_INFO, "CTRL: Session timed out, ending call");
goto leave_clear_call;
}
}
/* Finished! :-) */
leave_drop_call:
NOTE_VALUE(PAC, call_id_pair, htons(-1));
NOTE_VALUE(PNS, call_id_pair, htons(-1));
close(clientSocket);
leave_clear_call:
/* leave clientSocket and call_id_pair alone for bail() */
if (gre_fd != -1)
close(gre_fd);
gre_fd = -1;
if (pty_fd != -1)
close(pty_fd);
pty_fd = -1;
return;
#ifdef init
#undef init
#endif
}
/*** pptp_gre_copy ************************************************************/
void pptp_gre_copy(u_int16_t call_id, u_int16_t peer_call_id,
int pty_fd, int gre_fd)
{
int max_fd;
pptp_gre_call_id = call_id;
pptp_gre_peer_call_id = peer_call_id;
/* Pseudo-terminal already open. */
ack_sent = ack_recv = seq_sent = seq_recv = 0;
/* weird select semantics */
max_fd = gre_fd;
if (pty_fd > max_fd) max_fd = pty_fd;
/* Dispatch loop */
for (;;) { /* until error happens on gre_fd or pty_fd */
struct timeval tv = {0, 0};
struct timeval *tvp;
fd_set rfds;
int retval;
pqueue_t *head;
int block_usecs = -1; /* wait forever */
/* watch terminal and socket for input */
FD_ZERO(&rfds);
FD_SET(gre_fd, &rfds);
FD_SET(pty_fd, &rfds);
/*
* if there are multiple pending ACKs, then do a minimal timeout;
* else if there is a single pending ACK then timeout after 0,5 seconds;
* else block until data is available.
*/
if (ack_sent != seq_recv) {
if (ack_sent + 1 == seq_recv) /* u_int wrap-around safe */
block_usecs = 500000;
else
/* don't use zero, this will force a resceduling */
/* when calling select(), giving pppd a chance to */
/* run. */
block_usecs = 1;
}
/* otherwise block_usecs == -1, which means wait forever */
/*
* If there is a packet in the queue, then don't wait longer than
* the time remaining until it expires.
*/
head = pqueue_head();
if (head != NULL) {
int expiry_time = pqueue_expiry_time(head);
if (block_usecs == -1 || expiry_time < block_usecs)
block_usecs = expiry_time;
}
if (block_usecs == -1) {
tvp = NULL;
} else {
tvp = &tv;
tv.tv_usec = block_usecs;
tv.tv_sec = tv.tv_usec / 1000000;
tv.tv_usec %= 1000000;
}
retval = select(max_fd + 1, &rfds, NULL, NULL, tvp);
if (retval > 0 && FD_ISSET(pty_fd, &rfds)) {
if (decaps_hdlc(pty_fd, encaps_gre, gre_fd) < 0)
break;
} else if (retval == 0 && ack_sent != seq_recv) {
/* if outstanding ack */
/* send ack with no payload */
encaps_gre(gre_fd, NULL, 0);
}
if (retval > 0 && FD_ISSET(gre_fd, &rfds)) {
if (decaps_gre (gre_fd, encaps_hdlc, pty_fd) < 0)
break;
}
if (dequeue_gre (encaps_hdlc, pty_fd) < 0)
break;
}
/* Close up when done. */
close(gre_fd);
close(pty_fd);
}
