/*      $OpenBSD: packet.c,v 1.38 2024/08/21 15:18:00 florian Exp $ */

/*
 * Copyright (c) 2004, 2005 Esben Norby <norby@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>

#include <netinet/in.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <net/if_dl.h>

#include <errno.h>
#include <event.h>
#include <stdlib.h>
#include <string.h>

#include "ospfd.h"
#include "ospf.h"
#include "log.h"
#include "ospfe.h"

int              ip_hdr_sanity_check(const struct ip *, u_int16_t);
int              ospf_hdr_sanity_check(const struct ip *,
                    struct ospf_hdr *, u_int16_t, const struct iface *);
struct iface    *find_iface(struct ospfd_conf *, unsigned int, struct in_addr);

static u_int8_t *recv_buf;

int
gen_ospf_hdr(struct ibuf *buf, struct iface *iface, u_int8_t type)
{
        struct ospf_hdr ospf_hdr;

        bzero(&ospf_hdr, sizeof(ospf_hdr));
        ospf_hdr.version = OSPF_VERSION;
        ospf_hdr.type = type;
        ospf_hdr.rtr_id = ospfe_router_id();
        if (iface->type != IF_TYPE_VIRTUALLINK)
                ospf_hdr.area_id = iface->area->id.s_addr;
        ospf_hdr.auth_type = htons(iface->auth_type);

        return (ibuf_add(buf, &ospf_hdr, sizeof(ospf_hdr)));
}

/* send and receive packets */
int
send_packet(struct iface *iface, struct ibuf *buf, struct sockaddr_in *dst)
{
        struct msghdr            msg;
        struct iovec             iov[2];
        struct ip                ip_hdr;

        /* setup IP hdr */
        bzero(&ip_hdr, sizeof(ip_hdr));
        ip_hdr.ip_v = IPVERSION;
        ip_hdr.ip_hl = sizeof(ip_hdr) >> 2;
        ip_hdr.ip_tos = IPTOS_PREC_INTERNETCONTROL;
        ip_hdr.ip_len = htons(ibuf_size(buf) + sizeof(ip_hdr));
        ip_hdr.ip_id = 0;  /* 0 means kernel set appropriate value */
        ip_hdr.ip_off = 0;
        ip_hdr.ip_ttl = iface->type != IF_TYPE_VIRTUALLINK ?
            IP_DEFAULT_MULTICAST_TTL : MAXTTL;
        ip_hdr.ip_p = IPPROTO_OSPF;
        ip_hdr.ip_sum = 0;
        ip_hdr.ip_src = iface->addr;
        ip_hdr.ip_dst = dst->sin_addr;

        /* setup buffer */
        bzero(&msg, sizeof(msg));
        iov[0].iov_base = &ip_hdr;
        iov[0].iov_len = sizeof(ip_hdr);
        iov[1].iov_base = ibuf_data(buf);
        iov[1].iov_len = ibuf_size(buf);
        msg.msg_name = dst;
        msg.msg_namelen = sizeof(*dst);
        msg.msg_iov = iov;
        msg.msg_iovlen = 2;

        /* set outgoing interface for multicast traffic */
        if (IN_MULTICAST(ntohl(dst->sin_addr.s_addr)))
                if (if_set_mcast(iface) == -1)
                        return (-1);

        if (sendmsg(iface->fd, &msg, 0) == -1) {
                log_warn("%s: error sending packet to %s on interface %s",
                    __func__, inet_ntoa(ip_hdr.ip_dst), iface->name);
                return (-1);
        }

        return (0);
}

void
recv_packet(int fd, short event, void *bula)
{
        union {
                struct cmsghdr hdr;
                char    buf[CMSG_SPACE(sizeof(struct sockaddr_dl))];
        } cmsgbuf;
        struct msghdr            msg;
        struct iovec             iov;
        struct ip                ip_hdr;
        struct in_addr           addr;
        struct ospfd_conf       *xconf = bula;
        struct ospf_hdr         *ospf_hdr;
        struct iface            *iface;
        struct nbr              *nbr = NULL;
        char                    *buf;
        struct cmsghdr          *cmsg;
        ssize_t                  r;
        u_int16_t                len;
        int                      l;
        unsigned int             ifindex = 0;

        if (event != EV_READ)
                return;

        if (recv_buf == NULL)
                if ((recv_buf = malloc(READ_BUF_SIZE)) == NULL)
                        fatal(__func__);

        /* setup buffer */
        bzero(&msg, sizeof(msg));
        iov.iov_base = buf = recv_buf;
        iov.iov_len = READ_BUF_SIZE;
        msg.msg_iov = &iov;
        msg.msg_iovlen = 1;
        msg.msg_control = &cmsgbuf.buf;
        msg.msg_controllen = sizeof(cmsgbuf.buf);

        if ((r = recvmsg(fd, &msg, 0)) == -1) {
                if (errno != EAGAIN && errno != EINTR)
                        log_debug("recv_packet: read error: %s",
                            strerror(errno));
                return;
        }
        for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
            cmsg = CMSG_NXTHDR(&msg, cmsg)) {
                if (cmsg->cmsg_level == IPPROTO_IP &&
                    cmsg->cmsg_type == IP_RECVIF) {
                        ifindex = ((struct sockaddr_dl *)
                            CMSG_DATA(cmsg))->sdl_index;
                        break;
                }
        }

        len = (u_int16_t)r;

        /* IP header sanity checks */
        if (len < sizeof(ip_hdr)) {
                log_warnx("recv_packet: bad packet size");
                return;
        }
        memcpy(&ip_hdr, buf, sizeof(ip_hdr));
        if ((l = ip_hdr_sanity_check(&ip_hdr, len)) == -1)
                return;
        buf += l;
        len -= l;

        /* find a matching interface */
        if ((iface = find_iface(xconf, ifindex, ip_hdr.ip_src)) == NULL) {
                /* XXX add a counter here */
                return;
        }

        /*
         * Packet needs to be sent to AllSPFRouters or AllDRouters
         * or to the address of the interface itself.
         * AllDRouters is only valid for DR and BDR but this is checked later.
         */
        inet_pton(AF_INET, AllSPFRouters, &addr);
        if (ip_hdr.ip_dst.s_addr != addr.s_addr) {
                inet_pton(AF_INET, AllDRouters, &addr);
                if (ip_hdr.ip_dst.s_addr != addr.s_addr) {
                        if (ip_hdr.ip_dst.s_addr != iface->addr.s_addr) {
                                log_debug("recv_packet: packet sent to wrong "
                                    "address %s, interface %s",
                                    inet_ntoa(ip_hdr.ip_dst), iface->name);
                                return;
                        }
                }
        }

        /* OSPF header sanity checks */
        if (len < sizeof(*ospf_hdr)) {
                log_debug("recv_packet: bad packet size");
                return;
        }
        ospf_hdr = (struct ospf_hdr *)buf;

        if ((l = ospf_hdr_sanity_check(&ip_hdr, ospf_hdr, len, iface)) == -1)
                return;

        nbr = nbr_find_id(iface, ospf_hdr->rtr_id);
        if (ospf_hdr->type != PACKET_TYPE_HELLO && nbr == NULL) {
                log_debug("recv_packet: unknown neighbor ID");
                return;
        }

        if (auth_validate(buf, len, iface, nbr)) {
                if (nbr == NULL)
                        log_warnx("recv_packet: authentication error, "
                            "interface %s", iface->name);
                else
                        log_warnx("recv_packet: authentication error, "
                            "neighbor ID %s interface %s",
                            inet_ntoa(nbr->id), iface->name);
                return;
        }

        buf += sizeof(*ospf_hdr);
        len = l - sizeof(*ospf_hdr);

        /* switch OSPF packet type */
        switch (ospf_hdr->type) {
        case PACKET_TYPE_HELLO:
                inet_pton(AF_INET, AllSPFRouters, &addr);
                if (iface->type == IF_TYPE_BROADCAST ||
                    iface->type == IF_TYPE_POINTOPOINT)
                        if (ip_hdr.ip_dst.s_addr != addr.s_addr) {
                                log_warnx("%s: hello ignored on interface %s, "
                                    "invalid destination IP address %s",
                                    __func__, iface->name,
                                    inet_ntoa(ip_hdr.ip_dst));
                                break;
                        }

                recv_hello(iface, ip_hdr.ip_src, ospf_hdr->rtr_id, buf, len);
                break;
        case PACKET_TYPE_DD:
                recv_db_description(nbr, buf, len);
                break;
        case PACKET_TYPE_LS_REQUEST:
                recv_ls_req(nbr, buf, len);
                break;
        case PACKET_TYPE_LS_UPDATE:
                recv_ls_update(nbr, buf, len);
                break;
        case PACKET_TYPE_LS_ACK:
                recv_ls_ack(nbr, buf, len);
                break;
        default:
                log_debug("recv_packet: unknown OSPF packet type, interface %s",
                    iface->name);
        }
}

int
ip_hdr_sanity_check(const struct ip *ip_hdr, u_int16_t len)
{
        if (ntohs(ip_hdr->ip_len) != len) {
                log_debug("recv_packet: invalid IP packet length %u",
                    ntohs(ip_hdr->ip_len));
                return (-1);
        }

        if (ip_hdr->ip_p != IPPROTO_OSPF)
                /* this is enforced by the socket itself */
                fatalx("recv_packet: invalid IP proto");

        return (ip_hdr->ip_hl << 2);
}

int
ospf_hdr_sanity_check(const struct ip *ip_hdr, struct ospf_hdr *ospf_hdr,
    u_int16_t len, const struct iface *iface)
{
        struct in_addr           addr;

        if (ospf_hdr->version != OSPF_VERSION) {
                log_debug("recv_packet: invalid OSPF version %d",
                    ospf_hdr->version);
                return (-1);
        }

        if (ntohs(ospf_hdr->len) > len ||
            len <= sizeof(struct ospf_hdr)) {
                log_debug("recv_packet: invalid OSPF packet length %d",
                    ntohs(ospf_hdr->len));
                return (-1);
        }

        if (iface->type != IF_TYPE_VIRTUALLINK) {
                if (ospf_hdr->area_id != iface->area->id.s_addr) {
                        addr.s_addr = ospf_hdr->area_id;
                        log_debug("recv_packet: invalid area ID %s, "
                            "interface %s", inet_ntoa(addr), iface->name);
                        return (-1);
                }
        } else {
                if (ospf_hdr->area_id != 0) {
                        addr.s_addr = ospf_hdr->area_id;
                        log_debug("recv_packet: invalid area ID %s, "
                            "interface %s", inet_ntoa(addr), iface->name);
                        return (-1);
                }
        }

        if (iface->type == IF_TYPE_BROADCAST || iface->type == IF_TYPE_NBMA) {
                inet_pton(AF_INET, AllDRouters, &addr);
                if (ip_hdr->ip_dst.s_addr == addr.s_addr &&
                    (iface->state & IF_STA_DRORBDR) == 0) {
                        log_debug("recv_packet: invalid destination IP in "
                            "state %s, interface %s",
                            if_state_name(iface->state), iface->name);
                        return (-1);
                }
        }

        return (ntohs(ospf_hdr->len));
}

struct iface *
find_iface(struct ospfd_conf *xconf, unsigned int ifindex, struct in_addr src)
{
        struct area     *area = NULL;
        struct iface    *iface = NULL;

        /* returned interface needs to be active */
        LIST_FOREACH(area, &xconf->area_list, entry) {
                LIST_FOREACH(iface, &area->iface_list, entry) {
                        switch (iface->type) {
                        case IF_TYPE_VIRTUALLINK:
                                if ((src.s_addr == iface->dst.s_addr) &&
                                    !iface->passive)
                                        return (iface);
                                break;
                        case IF_TYPE_POINTOPOINT:
                                if (ifindex == iface->ifindex &&
                                    !iface->passive)
                                        return (iface);
                                break;
                        default:
                                if (ifindex == iface->ifindex &&
                                    (iface->addr.s_addr & iface->mask.s_addr) ==
                                    (src.s_addr & iface->mask.s_addr) &&
                                    !iface->passive)
                                        return (iface);
                                break;
                        }
                }
        }

        return (NULL);
}