/*
 * rfcomm_pppd.c
 */

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2001-2008 Maksim Yevmenkin <m_evmenkin@yahoo.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $Id: rfcomm_pppd.c,v 1.5 2003/09/07 18:32:11 max Exp $
 */
#define L2CAP_SOCKET_CHECKED
#include <bluetooth.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <sdp.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#define RFCOMM_PPPD     "rfcomm_pppd"

int             rfcomm_channel_lookup   (bdaddr_t const *local,
                                         bdaddr_t const *remote,
                                         int service, int *channel, int *error);

static void     exec_ppp        (int s, char *unit, char *label);
static void     sighandler      (int s);
static void     usage           (void);

static int      done;

/* Main */
int
main(int argc, char *argv[])
{
        struct sockaddr_rfcomm   sock_addr;
        char                    *label = NULL, *unit = NULL, *ep = NULL;
        bdaddr_t                 addr;
        int                      s, channel, detach, server, service,
                                 regdun, regsp;
        pid_t                    pid;

        memcpy(&addr, NG_HCI_BDADDR_ANY, sizeof(addr));
        channel = 0;
        detach = 1;
        server = 0;
        service = 0;
        regdun = 0;
        regsp = 0;

        /* Parse command line arguments */
        while ((s = getopt(argc, argv, "a:cC:dDhl:sSu:")) != -1) {
                switch (s) {
                case 'a': /* BDADDR */
                        if (!bt_aton(optarg, &addr)) {
                                struct hostent  *he = NULL;

                                if ((he = bt_gethostbyname(optarg)) == NULL)
                                        errx(1, "%s: %s", optarg, hstrerror(h_errno));

                                memcpy(&addr, he->h_addr, sizeof(addr));
                        }
                        break;

                case 'c': /* client */
                        server = 0;
                        break;

                case 'C': /* RFCOMM channel */
                        channel = strtoul(optarg, &ep, 10);
                        if (*ep != '\0') {
                                channel = 0;
                                switch (tolower(optarg[0])) {
                                case 'd': /* DialUp Networking */
                                        service = SDP_SERVICE_CLASS_DIALUP_NETWORKING;
                                        break;

                                case 'l': /* LAN Access Using PPP */
                                        service = SDP_SERVICE_CLASS_LAN_ACCESS_USING_PPP;
                                        break;
                                }
                        }
                        break;

                case 'd': /* do not detach */
                        detach = 0;
                        break;

                case 'D': /* Register DUN service as well as LAN service */
                        regdun = 1;
                        break;

                case 'l': /* PPP label */
                        label = optarg;
                        break;

                case 's': /* server */
                        server = 1;
                        break;

                case 'S': /* Register SP service as well as LAN service */
                        regsp = 1;
                        break;

                case 'u': /* PPP -unit option */
                        strtoul(optarg, &ep, 10);
                        if (*ep != '\0')
                                usage();
                                /* NOT REACHED */

                        unit = optarg;
                        break;

                case 'h':
                default:
                        usage();
                        /* NOT REACHED */
                }
        }

        /* Check if we got everything we wanted */
        if (label == NULL)
                errx(1, "Must specify PPP label");

        if (!server) {
                if (memcmp(&addr, NG_HCI_BDADDR_ANY, sizeof(addr)) == 0)
                        errx(1, "Must specify server BD_ADDR");

                /* Check channel, if was not set then obtain it via SDP */
                if (channel == 0 && service != 0)
                        if (rfcomm_channel_lookup(NULL, &addr, service,
                                                        &channel, &s) != 0)
                                errc(1, s, "Could not obtain RFCOMM channel");
        }

        if (channel <= 0 || channel > 30)
                errx(1, "Invalid RFCOMM channel number %d", channel);

        openlog(RFCOMM_PPPD, LOG_PID | LOG_PERROR | LOG_NDELAY, LOG_USER);

        if (detach && daemon(0, 0) < 0) {
                syslog(LOG_ERR, "Could not daemon(0, 0). %s (%d)",
                        strerror(errno), errno);
                exit(1);
        }

        s = socket(PF_BLUETOOTH, SOCK_STREAM, BLUETOOTH_PROTO_RFCOMM);
        if (s < 0) {
                syslog(LOG_ERR, "Could not create socket. %s (%d)",
                        strerror(errno), errno);
                exit(1);
        }

        if (server) {
                struct sigaction         sa;
                void                    *ss = NULL;
                sdp_lan_profile_t        lan;

                /* Install signal handler */
                memset(&sa, 0, sizeof(sa));
                sa.sa_handler = sighandler;

                if (sigaction(SIGTERM, &sa, NULL) < 0) {
                        syslog(LOG_ERR, "Could not sigaction(SIGTERM). %s (%d)",
                                strerror(errno), errno);
                        exit(1);
                }

                if (sigaction(SIGHUP, &sa, NULL) < 0) {
                        syslog(LOG_ERR, "Could not sigaction(SIGHUP). %s (%d)",
                                strerror(errno), errno);
                        exit(1);
                }

                if (sigaction(SIGINT, &sa, NULL) < 0) {
                        syslog(LOG_ERR, "Could not sigaction(SIGINT). %s (%d)",
                                strerror(errno), errno);
                        exit(1);
                }

                sa.sa_handler = SIG_IGN;
                sa.sa_flags = SA_NOCLDWAIT;

                if (sigaction(SIGCHLD, &sa, NULL) < 0) {
                        syslog(LOG_ERR, "Could not sigaction(SIGCHLD). %s (%d)",
                                strerror(errno), errno);
                        exit(1);
                }

                /* bind socket and listen for incoming connections */
                sock_addr.rfcomm_len = sizeof(sock_addr);
                sock_addr.rfcomm_family = AF_BLUETOOTH;
                memcpy(&sock_addr.rfcomm_bdaddr, &addr,
                        sizeof(sock_addr.rfcomm_bdaddr));
                sock_addr.rfcomm_channel = channel;

                if (bind(s, (struct sockaddr *) &sock_addr,
                                sizeof(sock_addr)) < 0) {
                        syslog(LOG_ERR, "Could not bind socket. %s (%d)",
                                strerror(errno), errno);
                        exit(1);
                }

                if (listen(s, 10) < 0) {
                        syslog(LOG_ERR, "Could not listen on socket. %s (%d)",
                                strerror(errno), errno);
                        exit(1);
                }

                ss = sdp_open_local(NULL);
                if (ss == NULL) {
                        syslog(LOG_ERR, "Unable to create local SDP session");
                        exit(1);
                }

                if (sdp_error(ss) != 0) {
                        syslog(LOG_ERR, "Unable to open local SDP session. " \
                                "%s (%d)", strerror(sdp_error(ss)),
                                sdp_error(ss));
                        exit(1);
                }

                memset(&lan, 0, sizeof(lan));
                lan.server_channel = channel;

                if (sdp_register_service(ss,
                                SDP_SERVICE_CLASS_LAN_ACCESS_USING_PPP,
                                &addr, (void *) &lan, sizeof(lan), NULL) != 0) {
                        syslog(LOG_ERR, "Unable to register LAN service with " \
                                "local SDP daemon. %s (%d)",
                                strerror(sdp_error(ss)), sdp_error(ss));
                        exit(1);
                }

                /*
                 * Register DUN (Dial-Up Networking) service on the same
                 * RFCOMM channel if requested. There is really no good reason
                 * to not to support this. AT-command exchange can be faked
                 * with chat script in ppp.conf
                 */

                if (regdun) {
                        sdp_dun_profile_t       dun;

                        memset(&dun, 0, sizeof(dun));
                        dun.server_channel = channel;

                        if (sdp_register_service(ss,
                                        SDP_SERVICE_CLASS_DIALUP_NETWORKING,
                                        &addr, (void *) &dun, sizeof(dun),
                                        NULL) != 0) {
                                syslog(LOG_ERR, "Unable to register DUN " \
                                        "service with local SDP daemon. " \
                                        "%s (%d)", strerror(sdp_error(ss)),
                                        sdp_error(ss));
                                exit(1);
                        }
                }

                /*
                 * Register SP (Serial Port) service on the same RFCOMM channel
                 * if requested. It appears that some cell phones are using so
                 * called "callback mechanism". In this scenario user is trying
                 * to connect his cell phone to the Internet, and, user's host
                 * computer is acting as the gateway server. It seems that it
                 * is not possible to tell the phone to just connect and start
                 * using the LAN service. Instead the user's host computer must
                 * "jump start" the phone by connecting to the phone's SP
                 * service. What happens next is the phone kills the existing
                 * connection and opens another connection back to the user's
                 * host computer. The phone really wants to use LAN service,
                 * but for whatever reason it looks for SP service on the
                 * user's host computer. This brain damaged behavior was
                 * reported for Nokia 6600 and Sony/Ericsson P900. Both phones
                 * are Symbian-based phones. Perhaps this is a Symbian problem?
                 */

                if (regsp) {
                        sdp_sp_profile_t        sp;

                        memset(&sp, 0, sizeof(sp));
                        sp.server_channel = channel;

                        if (sdp_register_service(ss,
                                        SDP_SERVICE_CLASS_SERIAL_PORT,
                                        &addr, (void *) &sp, sizeof(sp),
                                        NULL) != 0) {
                                syslog(LOG_ERR, "Unable to register SP " \
                                        "service with local SDP daemon. " \
                                        "%s (%d)", strerror(sdp_error(ss)),
                                        sdp_error(ss));
                                exit(1);
                        }
                }
                
                for (done = 0; !done; ) {
                        socklen_t       len = sizeof(sock_addr);
                        int             s1 = accept(s, (struct sockaddr *) &sock_addr, &len);

                        if (s1 < 0) {
                                syslog(LOG_ERR, "Could not accept connection " \
                                        "on socket. %s (%d)", strerror(errno),
                                        errno);
                                exit(1);
                        }
                                
                        pid = fork();
                        if (pid == (pid_t) -1) {
                                syslog(LOG_ERR, "Could not fork(). %s (%d)",
                                        strerror(errno), errno);
                                exit(1);
                        }

                        if (pid == 0) {
                                sdp_close(ss);
                                close(s);

                                /* Reset signal handler */
                                memset(&sa, 0, sizeof(sa));
                                sa.sa_handler = SIG_DFL;

                                sigaction(SIGTERM, &sa, NULL);
                                sigaction(SIGHUP, &sa, NULL);
                                sigaction(SIGINT, &sa, NULL);
                                sigaction(SIGCHLD, &sa, NULL);

                                /* Become daemon */
                                daemon(0, 0);

                                /*
                                 * XXX Make sure user does not shoot himself
                                 * in the foot. Do not pass unit option to the
                                 * PPP when operating in the server mode.
                                 */

                                exec_ppp(s1, NULL, label);
                        } else
                                close(s1);
                }
        } else {
                sock_addr.rfcomm_len = sizeof(sock_addr);
                sock_addr.rfcomm_family = AF_BLUETOOTH;
                memcpy(&sock_addr.rfcomm_bdaddr, NG_HCI_BDADDR_ANY,
                        sizeof(sock_addr.rfcomm_bdaddr));
                sock_addr.rfcomm_channel = 0;

                if (bind(s, (struct sockaddr *) &sock_addr,
                                sizeof(sock_addr)) < 0) {
                        syslog(LOG_ERR, "Could not bind socket. %s (%d)",
                                strerror(errno), errno);
                        exit(1);
                }

                memcpy(&sock_addr.rfcomm_bdaddr, &addr,
                        sizeof(sock_addr.rfcomm_bdaddr));
                sock_addr.rfcomm_channel = channel;

                if (connect(s, (struct sockaddr *) &sock_addr,
                                sizeof(sock_addr)) < 0) {
                        syslog(LOG_ERR, "Could not connect socket. %s (%d)",
                                strerror(errno), errno);
                        exit(1);
                }

                exec_ppp(s, unit, label);
        }

        exit(0);
} /* main */

/* 
 * Redirects stdin/stdout to s, stderr to /dev/null and exec
 * 'ppp -direct -quiet [-unit N] label'. Never returns.
 */

static void
exec_ppp(int s, char *unit, char *label)
{
        char     ppp[] = "/usr/sbin/ppp";
        char    *ppp_args[] = { ppp,  "-direct", "-quiet",
                                NULL, NULL,      NULL,     NULL };

        close(0);
        if (dup(s) < 0) {
                syslog(LOG_ERR, "Could not dup(0). %s (%d)",
                        strerror(errno), errno);
                exit(1);
        }

        close(1);
        if (dup(s) < 0) {
                syslog(LOG_ERR, "Could not dup(1). %s (%d)",
                        strerror(errno), errno);
                exit(1);
        }

        close(2);
        open("/dev/null", O_RDWR);

        if (unit != NULL) {
                ppp_args[3] = "-unit";
                ppp_args[4] = unit;
                ppp_args[5] = label;
        } else
                ppp_args[3] = label;

        if (execv(ppp, ppp_args) < 0) {
                syslog(LOG_ERR, "Could not exec(%s -direct -quiet%s%s %s). " \
                        "%s (%d)", ppp, (unit != NULL)? " -unit " : "",
                        (unit != NULL)? unit : "", label,
                        strerror(errno), errno);
                exit(1);
        }
} /* run_ppp */

/* Signal handler */
static void
sighandler(int s)
{
        done = 1;
} /* sighandler */

/* Display usage and exit */
static void
usage(void)
{
        fprintf(stdout,
"Usage: %s options\n" \
"Where options are:\n" \
"\t-a address   Address to listen on or connect to (required for client)\n" \
"\t-c           Act as a clinet (default)\n" \
"\t-C channel   RFCOMM channel to listen on or connect to (required)\n" \
"\t-d           Run in foreground\n" \
"\t-D           Register Dial-Up Networking service (server mode only)\n" \
"\t-l label     Use PPP label (required)\n" \
"\t-s           Act as a server\n" \
"\t-S           Register Serial Port service (server mode only)\n" \
"\t-u N         Tell PPP to operate on /dev/tunN (client mode only)\n" \
"\t-h           Display this message\n", RFCOMM_PPPD);

        exit(255);
} /* usage */