/*-
 * server.c
 *
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2004 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: server.c,v 1.6 2004/01/13 01:54:39 max Exp $
 */

#include <sys/param.h>
#include <sys/select.h>
#include <sys/stat.h>
#include <sys/queue.h>
#include <sys/ucred.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#define L2CAP_SOCKET_CHECKED
#include <bluetooth.h>
#include <errno.h>
#include <pwd.h>
#include <sdp.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "log.h"
#include "profile.h"
#include "provider.h"
#include "server.h"

static void     server_accept_client            (server_p srv, int32_t fd);
static int32_t  server_process_request          (server_p srv, int32_t fd);
static int32_t  server_send_error_response      (server_p srv, int32_t fd,
                                                 uint16_t error);
static void     server_close_fd                 (server_p srv, int32_t fd);

/*
 * Initialize server
 */

int32_t
server_init(server_p srv, char const *control)
{
        struct sockaddr_un      un;
        struct sockaddr_l2cap   l2;
        int32_t                 unsock, l2sock;
        socklen_t               size;
        uint16_t                imtu;

        assert(srv != NULL);
        assert(control != NULL);

        memset(srv, 0, sizeof(*srv));

        /* Open control socket */
        if (unlink(control) < 0 && errno != ENOENT) {
                log_crit("Could not unlink(%s). %s (%d)",
                        control, strerror(errno), errno);
                return (-1);
        }

        unsock = socket(PF_LOCAL, SOCK_STREAM, 0);
        if (unsock < 0) {
                log_crit("Could not create control socket. %s (%d)",
                        strerror(errno), errno);
                return (-1);
        }

        memset(&un, 0, sizeof(un));
        un.sun_len = sizeof(un);
        un.sun_family = AF_LOCAL;
        strlcpy(un.sun_path, control, sizeof(un.sun_path));

        if (bind(unsock, (struct sockaddr *) &un, sizeof(un)) < 0) {
                log_crit("Could not bind control socket. %s (%d)",
                        strerror(errno), errno);
                close(unsock);
                return (-1);
        }

        if (chmod(control, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH) < 0) {
                log_crit("Could not change permissions on control socket. " \
                        "%s (%d)", strerror(errno), errno);
                close(unsock);
                return (-1);
        }

        if (listen(unsock, 10) < 0) {
                log_crit("Could not listen on control socket. %s (%d)",
                        strerror(errno), errno);
                close(unsock);
                return (-1);
        }

        /* Open L2CAP socket */
        l2sock = socket(PF_BLUETOOTH, SOCK_SEQPACKET, BLUETOOTH_PROTO_L2CAP);
        if (l2sock < 0) {
                log_crit("Could not create L2CAP socket. %s (%d)",
                        strerror(errno), errno);
                close(unsock);
                return (-1);
        }

        size = sizeof(imtu);
        if (getsockopt(l2sock, SOL_L2CAP, SO_L2CAP_IMTU, &imtu, &size) < 0) {
                log_crit("Could not get L2CAP IMTU. %s (%d)",
                        strerror(errno), errno);
                close(unsock);
                close(l2sock);
                return (-1);
        }

        memset(&l2, 0, sizeof(l2));
        l2.l2cap_len = sizeof(l2);
        l2.l2cap_family = AF_BLUETOOTH;
        memcpy(&l2.l2cap_bdaddr, NG_HCI_BDADDR_ANY, sizeof(l2.l2cap_bdaddr));
        l2.l2cap_psm = htole16(NG_L2CAP_PSM_SDP);

        if (bind(l2sock, (struct sockaddr *) &l2, sizeof(l2)) < 0) {
                log_crit("Could not bind L2CAP socket. %s (%d)",
                        strerror(errno), errno);
                close(unsock);
                close(l2sock);
                return (-1);
        }

        if (listen(l2sock, 10) < 0) {
                log_crit("Could not listen on L2CAP socket. %s (%d)",
                        strerror(errno), errno);
                close(unsock);
                close(l2sock);
                return (-1);
        }

        /* Allocate incoming buffer */
        srv->imtu = (imtu > SDP_LOCAL_MTU)? imtu : SDP_LOCAL_MTU;
        srv->req = (uint8_t *) calloc(srv->imtu, sizeof(srv->req[0]));
        if (srv->req == NULL) {
                log_crit("Could not allocate request buffer");
                close(unsock);
                close(l2sock);
                return (-1);
        }

        /* Allocate memory for descriptor index */
        srv->fdidx = (fd_idx_p) calloc(FD_SETSIZE, sizeof(srv->fdidx[0]));
        if (srv->fdidx == NULL) {
                log_crit("Could not allocate fd index");
                free(srv->req);
                close(unsock);
                close(l2sock);
                return (-1);
        }

        /* Register Service Discovery profile (attach it to control socket) */
        if (provider_register_sd(unsock) < 0) {
                log_crit("Could not register Service Discovery profile");
                free(srv->fdidx);
                free(srv->req);
                close(unsock);
                close(l2sock);
                return (-1);
        }

        /*
         * If we got here then everything is fine. Add both control sockets
         * to the index.
         */

        FD_ZERO(&srv->fdset);
        srv->maxfd = (unsock > l2sock)? unsock : l2sock;
        
        FD_SET(unsock, &srv->fdset);
        srv->fdidx[unsock].valid = 1;
        srv->fdidx[unsock].server = 1;
        srv->fdidx[unsock].control = 1;
        srv->fdidx[unsock].priv = 0;
        srv->fdidx[unsock].rsp_cs = 0;
        srv->fdidx[unsock].rsp_size = 0;
        srv->fdidx[unsock].rsp_limit = 0;
        srv->fdidx[unsock].omtu = SDP_LOCAL_MTU;
        srv->fdidx[unsock].rsp = NULL;

        FD_SET(l2sock, &srv->fdset);
        srv->fdidx[l2sock].valid = 1;
        srv->fdidx[l2sock].server = 1;
        srv->fdidx[l2sock].control = 0;
        srv->fdidx[l2sock].priv = 0;
        srv->fdidx[l2sock].rsp_cs = 0;
        srv->fdidx[l2sock].rsp_size = 0;
        srv->fdidx[l2sock].rsp_limit = 0;
        srv->fdidx[l2sock].omtu = 0; /* unknown */
        srv->fdidx[l2sock].rsp = NULL;

        return (0);
}

/*
 * Shutdown server
 */

void
server_shutdown(server_p srv)
{
        int     fd;

        assert(srv != NULL);

        for (fd = 0; fd < srv->maxfd + 1; fd ++)
                if (srv->fdidx[fd].valid)
                        server_close_fd(srv, fd);

        free(srv->req);
        free(srv->fdidx);

        memset(srv, 0, sizeof(*srv));
}

/*
 * Do one server iteration
 */

int32_t
server_do(server_p srv)
{
        fd_set  fdset;
        int32_t n, fd;

        assert(srv != NULL);

        /* Copy cached version of the fd set and call select */
        memcpy(&fdset, &srv->fdset, sizeof(fdset));
        n = select(srv->maxfd + 1, &fdset, NULL, NULL, NULL);
        if (n < 0) {
                if (errno == EINTR)
                        return (0);

                log_err("Could not select(%d, %p). %s (%d)",
                        srv->maxfd + 1, &fdset, strerror(errno), errno);

                return (-1);
        }

        /* Process  descriptors */
        for (fd = 0; fd < srv->maxfd + 1 && n > 0; fd ++) {
                if (!FD_ISSET(fd, &fdset))
                        continue;

                assert(srv->fdidx[fd].valid);
                n --;

                if (srv->fdidx[fd].server)
                        server_accept_client(srv, fd);
                else if (server_process_request(srv, fd) != 0)
                        server_close_fd(srv, fd);
        }

        return (0);
        
}

/*
 * Accept new client connection and register it with index
 */

static void
server_accept_client(server_p srv, int32_t fd)
{
        uint8_t         *rsp = NULL;
        int32_t          cfd, priv;
        uint16_t         omtu;
        socklen_t        size;

        do {
                cfd = accept(fd, NULL, NULL);
        } while (cfd < 0 && errno == EINTR);

        if (cfd < 0) {
                log_err("Could not accept connection on %s socket. %s (%d)",
                        srv->fdidx[fd].control? "control" : "L2CAP",
                        strerror(errno), errno);
                return;
        }

        assert(!FD_ISSET(cfd, &srv->fdset));
        assert(!srv->fdidx[cfd].valid);

        priv = 0;

        if (!srv->fdidx[fd].control) {
                /* Get local BD_ADDR */
                size = sizeof(srv->req_sa);
                if (getsockname(cfd,(struct sockaddr*)&srv->req_sa,&size) < 0) {
                        log_err("Could not get local BD_ADDR. %s (%d)",
                                strerror(errno), errno);
                        close(cfd);
                        return;
                }

                /* Get outgoing MTU */
                size = sizeof(omtu);
                if (getsockopt(cfd,SOL_L2CAP,SO_L2CAP_OMTU,&omtu,&size) < 0) {
                        log_err("Could not get L2CAP OMTU. %s (%d)",
                                strerror(errno), errno);
                        close(cfd);
                        return;
                }

                /*
                 * The maximum size of the L2CAP packet is 65536 bytes.
                 * The minimum L2CAP MTU is 43 bytes. That means we need
                 * 65536 / 43 = ~1524 chunks to transfer maximum packet
                 * size with minimum MTU. The "rsp_cs" field in fd_idx_t
                 * is 11 bits wide, which gives us up to 2048 chunks.
                 */

                if (omtu < NG_L2CAP_MTU_MINIMUM) {
                        log_err("L2CAP OMTU is too small (%d bytes)", omtu);
                        close(cfd);
                        return;
                }
        } else {
                uid_t            uid;
                gid_t            gid;
                struct passwd   *pw;

                /* Get peer's credentials */
                if (getpeereid(cfd, &uid, &gid) < 0) {
                        log_err("Could not get peer's credentials. %s (%d)",
                                strerror(errno), errno);
                        close(cfd);
                        return;
                }

                /* Check credentials */
                pw = getpwuid(uid);
                if (pw != NULL)
                        priv = (strcmp(pw->pw_name, "root") == 0);
                else
                        log_warning("Could not verify credentials for uid %d",
                                uid);

                memcpy(&srv->req_sa.l2cap_bdaddr, NG_HCI_BDADDR_ANY,
                        sizeof(srv->req_sa.l2cap_bdaddr));

                omtu = srv->fdidx[fd].omtu;
        }

        /*
         * Allocate buffer. This is an overkill, but we can not know how 
         * big our reply is going to be.
         */

        rsp = (uint8_t *) calloc(NG_L2CAP_MTU_MAXIMUM, sizeof(rsp[0]));
        if (rsp == NULL) {
                log_crit("Could not allocate response buffer");
                close(cfd);
                return;
        }

        /* Add client descriptor to the index */
        FD_SET(cfd, &srv->fdset);
        if (srv->maxfd < cfd)
                srv->maxfd = cfd;
        srv->fdidx[cfd].valid = 1;
        srv->fdidx[cfd].server = 0;
        srv->fdidx[cfd].control = srv->fdidx[fd].control;
        srv->fdidx[cfd].priv = priv;
        srv->fdidx[cfd].rsp_cs = 0;
        srv->fdidx[cfd].rsp_size = 0;
        srv->fdidx[cfd].rsp_limit = 0;
        srv->fdidx[cfd].omtu = omtu;
        srv->fdidx[cfd].rsp = rsp;
}

/*
 * Process request from the client
 */

static int32_t
server_process_request(server_p srv, int32_t fd)
{
        sdp_pdu_p       pdu = (sdp_pdu_p) srv->req;
        int32_t         len, error;

        assert(srv->imtu > 0);
        assert(srv->req != NULL);
        assert(FD_ISSET(fd, &srv->fdset));
        assert(srv->fdidx[fd].valid);
        assert(!srv->fdidx[fd].server);
        assert(srv->fdidx[fd].rsp != NULL);
        assert(srv->fdidx[fd].omtu >= NG_L2CAP_MTU_MINIMUM);

        do {
                len = read(fd, srv->req, srv->imtu);
        } while (len < 0 && errno == EINTR);

        if (len < 0) {
                log_err("Could not receive SDP request from %s socket. %s (%d)",
                        srv->fdidx[fd].control? "control" : "L2CAP",
                        strerror(errno), errno);
                return (-1);
        }
        if (len == 0) {
                log_info("Client on %s socket has disconnected",
                        srv->fdidx[fd].control? "control" : "L2CAP");
                return (-1);
        }

        if (len >= sizeof(*pdu) &&
            sizeof(*pdu) + (pdu->len = ntohs(pdu->len)) == len) {
                switch (pdu->pid) {
                case SDP_PDU_SERVICE_SEARCH_REQUEST:
                        error = server_prepare_service_search_response(srv, fd);
                        break;

                case SDP_PDU_SERVICE_ATTRIBUTE_REQUEST:
                        error = server_prepare_service_attribute_response(srv, fd);
                        break;

                case SDP_PDU_SERVICE_SEARCH_ATTRIBUTE_REQUEST:
                        error = server_prepare_service_search_attribute_response(srv, fd);
                        break;

                case SDP_PDU_SERVICE_REGISTER_REQUEST:
                        error = server_prepare_service_register_response(srv, fd);
                        break;

                case SDP_PDU_SERVICE_UNREGISTER_REQUEST:
                        error = server_prepare_service_unregister_response(srv, fd);
                        break;

                case SDP_PDU_SERVICE_CHANGE_REQUEST:
                        error = server_prepare_service_change_response(srv, fd);
                        break;

                default:
                        error = SDP_ERROR_CODE_INVALID_REQUEST_SYNTAX;
                        break;
                }
        } else
                error = SDP_ERROR_CODE_INVALID_PDU_SIZE;

        if (error == 0) {
                switch (pdu->pid) {
                case SDP_PDU_SERVICE_SEARCH_REQUEST:
                        error = server_send_service_search_response(srv, fd);
                        break;

                case SDP_PDU_SERVICE_ATTRIBUTE_REQUEST:
                        error = server_send_service_attribute_response(srv, fd);
                        break;

                case SDP_PDU_SERVICE_SEARCH_ATTRIBUTE_REQUEST:
                        error = server_send_service_search_attribute_response(srv, fd);
                        break;

                case SDP_PDU_SERVICE_REGISTER_REQUEST:
                        error = server_send_service_register_response(srv, fd);
                        break;

                case SDP_PDU_SERVICE_UNREGISTER_REQUEST:
                        error = server_send_service_unregister_response(srv, fd);
                        break;

                case SDP_PDU_SERVICE_CHANGE_REQUEST:
                        error = server_send_service_change_response(srv, fd);
                        break;

                default:
                        error = SDP_ERROR_CODE_INVALID_REQUEST_SYNTAX;
                        break;
                }

                if (error != 0)
                        log_err("Could not send SDP response to %s socket, " \
                                "pdu->pid=%d, pdu->tid=%d, error=%d",
                                srv->fdidx[fd].control? "control" : "L2CAP", 
                                pdu->pid, ntohs(pdu->tid), error);
        } else {
                log_err("Could not process SDP request from %s socket, " \
                        "pdu->pid=%d, pdu->tid=%d, pdu->len=%d, len=%d, " \
                        "error=%d",
                        srv->fdidx[fd].control? "control" : "L2CAP", 
                        pdu->pid, ntohs(pdu->tid), pdu->len, len, error);

                error = server_send_error_response(srv, fd, error);
                if (error != 0)
                        log_err("Could not send SDP error response to %s " \
                                "socket, pdu->pid=%d, pdu->tid=%d, error=%d",
                                srv->fdidx[fd].control? "control" : "L2CAP",
                                pdu->pid, ntohs(pdu->tid), error);
        }

        /* On error forget response (if any) */ 
        if (error != 0) {
                srv->fdidx[fd].rsp_cs = 0;
                srv->fdidx[fd].rsp_size = 0;
                srv->fdidx[fd].rsp_limit = 0;
        }

        return (error);
}

/*
 * Send SDP_Error_Response PDU
 */

static int32_t
server_send_error_response(server_p srv, int32_t fd, uint16_t error)
{
        int32_t size;

        struct {
                sdp_pdu_t               pdu;
                uint16_t                error;
        } __attribute__ ((packed))      rsp;

        /* Prepare and send SDP error response */
        rsp.pdu.pid = SDP_PDU_ERROR_RESPONSE;
        rsp.pdu.tid = ((sdp_pdu_p)(srv->req))->tid;
        rsp.pdu.len = htons(sizeof(rsp.error));
        rsp.error   = htons(error);

        do {
                size = write(fd, &rsp, sizeof(rsp));
        } while (size < 0 && errno == EINTR);

        return ((size < 0)? errno : 0);
}

/*
 * Close descriptor and remove it from index
 */

static void
server_close_fd(server_p srv, int32_t fd)
{
        provider_p      provider = NULL, provider_next = NULL;

        assert(FD_ISSET(fd, &srv->fdset));
        assert(srv->fdidx[fd].valid);

        close(fd);

        FD_CLR(fd, &srv->fdset);
        if (fd == srv->maxfd)
                srv->maxfd --;

        if (srv->fdidx[fd].rsp != NULL)
                free(srv->fdidx[fd].rsp);

        memset(&srv->fdidx[fd], 0, sizeof(srv->fdidx[fd]));

        for (provider = provider_get_first();
             provider != NULL;
             provider = provider_next) {
                provider_next = provider_get_next(provider);

                if (provider->fd == fd)
                        provider_unregister(provider);
        }
}