/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include "libnm-glib-aux/nm-default-glib-i18n-lib.h"

#include "nm-lldp-network.h"

#include <linux/filter.h>
#include <linux/if_packet.h>
#include <netinet/if_ether.h>

int
nm_lldp_network_bind_raw_socket(int ifindex)
{
    static const struct sock_filter filter[] = {
        BPF_STMT(BPF_LD + BPF_W + BPF_ABS,
                 offsetof(struct ethhdr, h_dest)),             /* A <- 4 bytes of destination MAC */
        BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0180c200, 1, 0), /* A != 01:80:c2:00 */
        BPF_STMT(BPF_RET + BPF_K, 0),                          /* drop packet */
        BPF_STMT(BPF_LD + BPF_H + BPF_ABS,
                 offsetof(struct ethhdr, h_dest)
                     + 4), /* A <- remaining 2 bytes of destination MAC */
        BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0000, 3, 0),                    /* A != 00:00 */
        BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0003, 2, 0),                    /* A != 00:03 */
        BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x000e, 1, 0),                    /* A != 00:0e */
        BPF_STMT(BPF_RET + BPF_K, 0),                                         /* drop packet */
        BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ethhdr, h_proto)), /* A <- protocol */
        BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, NM_ETHERTYPE_LLDP, 1, 0), /* A != NM_ETHERTYPE_LLDP */
        BPF_STMT(BPF_RET + BPF_K, 0),                                 /* drop packet */
        BPF_STMT(BPF_RET + BPF_K, UINT32_MAX),                        /* accept packet */
    };
    static const struct sock_fprog fprog = {
        .len    = G_N_ELEMENTS(filter),
        .filter = (struct sock_filter *) filter,
    };
    struct packet_mreq mreq = {
        .mr_ifindex = ifindex,
        .mr_type    = PACKET_MR_MULTICAST,
        .mr_alen    = ETH_ALEN,
        .mr_address = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x00},
    };
    struct sockaddr_ll saddrll = {
        .sll_family  = AF_PACKET,
        .sll_ifindex = ifindex,
    };
    nm_auto_close int fd = -1;

    assert(ifindex > 0);

    fd = socket(AF_PACKET, SOCK_RAW | SOCK_CLOEXEC | SOCK_NONBLOCK, htobe16(NM_ETHERTYPE_LLDP));
    if (fd < 0)
        return -errno;

    if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog)) < 0)
        return -errno;

    /* customer bridge */
    if (setsockopt(fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
        return -errno;

    /* non TPMR bridge */
    mreq.mr_address[ETH_ALEN - 1] = 0x03;
    if (setsockopt(fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
        return -errno;

    /* nearest bridge */
    mreq.mr_address[ETH_ALEN - 1] = 0x0E;
    if (setsockopt(fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
        return -errno;

    if (bind(fd, (const struct sockaddr *) &saddrll, sizeof(saddrll)) < 0)
        return -errno;

    return nm_steal_fd(&fd);
}