/*      $OpenBSD: print-gre.c,v 1.35 2024/05/21 05:00:48 jsg Exp $      */

/*
 * Copyright (c) 2002 Jason L. Wright (jason@thought.net)
 * 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 ``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 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.
 */

/*
 * tcpdump filter for GRE - Generic Routing Encapsulation
 * RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE)
 */

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

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

#include <net/ethertypes.h>

#include <stdio.h>
#include <string.h>

#include "interface.h"
#include "addrtoname.h"
#include "extract.h"

#define GRE_CP          0x8000          /* checksum present */
#define GRE_RP          0x4000          /* routing present */
#define GRE_KP          0x2000          /* key present */
#define GRE_SP          0x1000          /* sequence# present */
#define GRE_sP          0x0800          /* source routing */
#define GRE_RECRS       0x0700          /* recursion count */
#define GRE_AP          0x0080          /* acknowledgment# present */
#define GRE_VERS        0x0007          /* protocol version */

/* source route entry types */
#define GRESRE_IP       0x0800          /* IP */
#define GRESRE_ASN      0xfffe          /* ASN */

#define NVGRE_VSID_MASK         0xffffff00U
#define NVGRE_VSID_SHIFT        8
#define NVGRE_FLOWID_MASK       0x000000ffU
#define NVGRE_FLOWID_SHIFT      0

#define GRE_WCCP        0x883e
#define ERSPAN_II       0x88be
#define ERSPAN_III      0x22eb

struct wccp_redirect {
        uint8_t         flags;
#define WCCP_D                  (1 << 7)
#define WCCP_A                  (1 << 6)
        uint8_t         ServiceId;
        uint8_t         AltBucket;
        uint8_t         PriBucket;
};

void gre_print_0(const u_char *, u_int);
void gre_print_1(const u_char *, u_int);
void gre_print_pptp(const u_char *, u_int, uint16_t);
void gre_print_eoip(const u_char *, u_int, uint16_t);
void gre_print_erspan(uint16_t, const u_char *, u_int);
void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int);
void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int);
void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int);

void
gre_print(const u_char *p, u_int length)
{
        uint16_t vers;
        int l;

        l = snapend - p;

        if (l < sizeof(vers)) {
                printf("[|gre]");
                return;
        }
        vers = EXTRACT_16BITS(p) & GRE_VERS;

        switch (vers) {
        case 0:
                gre_print_0(p, length);
                break;
        case 1:
                gre_print_1(p, length);
                break;
        default:
                printf("gre-unknown-version=%u", vers);
                break;
        }
}

void
gre_print_0(const u_char *p, u_int length)
{
        uint16_t flags, proto;
        u_int l;

        l = snapend - p;

        flags = EXTRACT_16BITS(p);
        p += sizeof(flags);
        l -= sizeof(flags);
        length -= sizeof(flags);

        printf("gre");

        if (vflag) {
                printf(" [%s%s%s%s%s]",
                    (flags & GRE_CP) ? "C" : "",
                    (flags & GRE_RP) ? "R" : "",
                    (flags & GRE_KP) ? "K" : "",
                    (flags & GRE_SP) ? "S" : "",
                    (flags & GRE_sP) ? "s" : "");
        }

        if (l < sizeof(proto))
                goto trunc;
        proto = EXTRACT_16BITS(p);
        p += sizeof(proto);
        l -= sizeof(proto);
        length -= sizeof(proto);

        if (vflag)
                printf(" %04x", proto);

        if ((flags & GRE_CP) | (flags & GRE_RP)) {
                if (l < 2)
                        goto trunc;
                if ((flags & GRE_CP) && vflag)
                        printf(" sum 0x%x", EXTRACT_16BITS(p));
                p += 2;
                l -= 2;
                length -= 2;

                if (l < 2)
                        goto trunc;
                if (flags & GRE_RP)
                        printf(" off 0x%x", EXTRACT_16BITS(p));
                p += 2;
                l -= 2;
                length -= 2;
        }

        if (flags & GRE_KP) {
                uint32_t key, vsid;

                if (l < sizeof(key))
                        goto trunc;
                key = EXTRACT_32BITS(p);
                p += sizeof(key);
                l -= sizeof(key);
                length -= sizeof(key);

                /* maybe NVGRE, or key entropy? */
                vsid = (key & NVGRE_VSID_MASK) >> NVGRE_VSID_SHIFT;
                printf(" key=%u|%u+%02x", key, vsid,
                    (key & NVGRE_FLOWID_MASK) >> NVGRE_FLOWID_SHIFT);
        }

        if (flags & GRE_SP) {
                if (l < 4)
                        goto trunc;
                printf(" seq %u", EXTRACT_32BITS(p));
                p += 4;
                l -= 4;
                length -= 4;
        }

        if (flags & GRE_RP) {
                for (;;) {
                        u_int16_t af;
                        u_int8_t sreoff;
                        u_int8_t srelen;

                        if (l < 4)
                                goto trunc;
                        af = EXTRACT_16BITS(p);
                        sreoff = *(p + 2);
                        srelen = *(p + 3);
                        p += 4;
                        l -= 4;
                        length -= 4;

                        if (af == 0 && srelen == 0)
                                break;

                        gre_sre_print(af, sreoff, srelen, p, l);

                        if (l < srelen)
                                goto trunc;
                        p += srelen;
                        l -= srelen;
                        length -= srelen;
                }
        }

        printf(" ");

        switch (packettype) {
        case PT_ERSPAN:
                gre_print_erspan(flags, p, length);
                return;
        default:
                break;
        }

        switch (proto) {
        case 0:
                printf("keep-alive");
                break;
        case GRE_WCCP: {
                printf("wccp ");

                if (l == 0)
                        return;

                if (*p >> 4 != 4) {
                        struct wccp_redirect *wccp;

                        if (l < sizeof(*wccp)) {
                                printf("[|wccp]");
                                return;
                        }

                        wccp = (struct wccp_redirect *)p;

                        printf("D:%c A:%c SId:%u Alt:%u Pri:%u",
                            (wccp->flags & WCCP_D) ? '1' : '0',
                            (wccp->flags & WCCP_A) ? '1' : '0',
                            wccp->ServiceId, wccp->AltBucket, wccp->PriBucket);

                        p += sizeof(*wccp);
                        l -= sizeof(*wccp);

                        printf(": ");
                }

                /* FALLTHROUGH */
        }
        case ETHERTYPE_IP:
                ip_print(p, length);
                break;
        case ETHERTYPE_IPV6:
                ip6_print(p, length);
                break;
        case ETHERTYPE_MPLS:
        case ETHERTYPE_MPLS_MCAST:
                mpls_print(p, length);
                break;
        case ETHERTYPE_TRANSETHER:
                ether_tryprint(p, length, 0);
                break;
#ifndef ETHERTYPE_NSH
#define ETHERTYPE_NSH 0x894f
#endif
        case ETHERTYPE_NSH:
                nsh_print(p, length);
                break;
        case ERSPAN_II:
                gre_print_erspan(flags, p, length);
                break;
        case 0x2000:
                cdp_print(p, length, l, 0);
                break;
#ifndef ETHERTYPE_NHRP
#define ETHERTYPE_NHRP 0x2001
#endif
        case ETHERTYPE_NHRP:
                nhrp_print(p, length);
                break;
        default:
                printf("unknown-proto-%04x", proto);
        }
        return;

trunc:
        printf("[|gre]");
}

void
gre_print_1(const u_char *p, u_int length)
{
        uint16_t flags, proto;
        int l;

        l = snapend - p;

        flags = EXTRACT_16BITS(p);
        p += sizeof(flags);
        l -= sizeof(flags);
        length -= sizeof(flags);

        if (l < sizeof(proto))
                goto trunc;

        proto = EXTRACT_16BITS(p);
        p += sizeof(proto);
        l -= sizeof(proto);
        length -= sizeof(proto);

        switch (proto) {
        case ETHERTYPE_PPP:
                gre_print_pptp(p, length, flags);
                break;
        case 0x6400:
                /* MikroTik RouterBoard Ethernet over IP (EoIP) */
                gre_print_eoip(p, length, flags);
                break;
        default:
                printf("unknown-gre1-proto-%04x", proto);
                break;
        }

        return;

trunc:
        printf("[|gre1]");
}

void
gre_print_pptp(const u_char *p, u_int length, uint16_t flags)
{
        uint16_t len;
        int l;

        l = snapend - p;

        printf("pptp");

        if (vflag) {
                printf(" [%s%s%s%s%s%s]",
                    (flags & GRE_CP) ? "C" : "",
                    (flags & GRE_RP) ? "R" : "",
                    (flags & GRE_KP) ? "K" : "",
                    (flags & GRE_SP) ? "S" : "",
                    (flags & GRE_sP) ? "s" : "",
                    (flags & GRE_AP) ? "A" : "");
        }

        if (flags & GRE_CP) {
                printf(" cpset!");
                return;
        }
        if (flags & GRE_RP) {
                printf(" rpset!");
                return;
        }
        if ((flags & GRE_KP) == 0) {
                printf(" kpunset!");
                return;
        }
        if (flags & GRE_sP) {
                printf(" spset!");
                return;
        }

        /* GRE_KP */
        if (l < sizeof(len))
                goto trunc;
        len = EXTRACT_16BITS(p);
        p += sizeof(len);
        l -= sizeof(len);
        length -= sizeof(len);

        if (vflag)
                printf(" len %u", EXTRACT_16BITS(p));

        if (l < 2)
                goto trunc;
        printf(" callid %u", EXTRACT_16BITS(p));
        p += 2;
        l -= 2;
        length -= 2;

        if (flags & GRE_SP) {
                if (l < 4)
                        goto trunc;
                printf(" seq %u", EXTRACT_32BITS(p));
                p += 4;
                l -= 4;
                length -= 4;
        }

        if (flags & GRE_AP) {
                if (l < 4)
                        goto trunc;
                printf(" ack %u", EXTRACT_32BITS(p));
                p += 4;
                l -= 4;
                length -= 4;
        }

        if ((flags & GRE_SP) == 0)
                return;

        if (length < len) {
                printf(" truncated-pptp - %d bytes missing!",
                    len - length);
                len = length;
        }

        printf(": ");

        ppp_hdlc_print(p, len);
        return;

trunc:
        printf("[|pptp]");
}

void
gre_print_eoip(const u_char *p, u_int length, uint16_t flags)
{
        uint16_t len, id;
        int l;

        l = snapend - p;

        printf("eoip");

        flags &= ~GRE_VERS;
        if (flags != GRE_KP) {
                printf(" unknown-eoip-flags-%04x!", flags);
                return;
        }

        if (l < sizeof(len))
                goto trunc;

        len = EXTRACT_16BITS(p);
        p += sizeof(len);
        l -= sizeof(len);
        length -= sizeof(len);

        if (l < sizeof(id))
                goto trunc;

        id = EXTRACT_LE_16BITS(p);
        p += sizeof(id);
        l -= sizeof(id);
        length -= sizeof(id);

        if (vflag)
                printf(" len=%u tunnel-id=%u", len, id);
        else
                printf(" %u", id);

        if (length < len) {
                printf(" truncated-eoip - %d bytes missing!",
                    len - length);
                len = length;
        }

        printf(": ");

        if (len == 0)
                printf("keepalive");
        else
                ether_tryprint(p, len, 0);

        return;

trunc:
        printf("[|eoip]");
}

#define ERSPAN2_VER_SHIFT       28
#define ERSPAN2_VER_MASK        (0xfU << ERSPAN2_VER_SHIFT)
#define ERSPAN2_VER             (0x1U << ERSPAN2_VER_SHIFT)
#define ERSPAN2_VLAN_SHIFT      16
#define ERSPAN2_VLAN_MASK       (0xfffU << ERSPAN2_VLAN_SHIFT)
#define ERSPAN2_COS_SHIFT       13
#define ERSPAN2_COS_MASK        (0x7U << ERSPAN2_COS_SHIFT)
#define ERSPAN2_EN_SHIFT        11
#define ERSPAN2_EN_MASK         (0x3U << ERSPAN2_EN_SHIFT)
#define ERSPAN2_EN_NONE         (0x0U << ERSPAN2_EN_SHIFT)
#define ERSPAN2_EN_ISL          (0x1U << ERSPAN2_EN_SHIFT)
#define ERSPAN2_EN_DOT1Q        (0x2U << ERSPAN2_EN_SHIFT)
#define ERSPAN2_EN_VLAN         (0x3U << ERSPAN2_EN_SHIFT)
#define ERSPAN2_T_SHIFT         10
#define ERSPAN2_T_MASK          (0x1U << ERSPAN2_T_SHIFT)
#define ERSPAN2_SID_SHIFT       0
#define ERSPAN2_SID_MASK        (0x3ffU << ERSPAN2_SID_SHIFT)

#define ERSPAN2_INDEX_SHIFT     0
#define ERSPAN2_INDEX_MASK      (0xfffffU << ERSPAN2_INDEX_SHIFT)

void
gre_print_erspan(uint16_t flags, const u_char *bp, u_int len)
{
        uint32_t hdr, ver, vlan, cos, en, sid, index;
        u_int l;

        printf("erspan");

        if (!(flags & GRE_SP)) {
                printf(" I: ");
                ether_tryprint(bp, len, 0);
                return;
        }

        l = snapend - bp;
        if (l < sizeof(hdr))
                goto trunc;

        hdr = EXTRACT_32BITS(bp);
        bp += sizeof(hdr);
        l -= sizeof(hdr);
        len -= sizeof(hdr);

        ver = hdr & ERSPAN2_VER_MASK;
        if (ver != ERSPAN2_VER) {
                ver >>= ERSPAN2_VER_SHIFT;
                printf(" erspan-unknown-version-%x", ver);
                return;
        }

        if (vflag)
                printf(" II");

        sid = (hdr & ERSPAN2_SID_MASK) >> ERSPAN2_SID_SHIFT;
        printf(" session %u", sid);

        en = hdr & ERSPAN2_EN_MASK;
        vlan = (hdr & ERSPAN2_VLAN_MASK) >> ERSPAN2_VLAN_SHIFT;
        switch (en) {
        case ERSPAN2_EN_NONE:
                break;
        case ERSPAN2_EN_ISL:
                printf(" isl %u", vlan);
                break;
        case ERSPAN2_EN_DOT1Q:
                printf(" vlan %u", vlan);
                break;
        case ERSPAN2_EN_VLAN:
                printf(" vlan payload");
                break;
        }

        if (vflag) {
                cos = (hdr & ERSPAN2_COS_MASK) >> ERSPAN2_COS_SHIFT;
                printf(" cos %u", cos);

                if (hdr & ERSPAN2_T_MASK)
                        printf(" truncated");
        }

        if (l < sizeof(hdr))
                goto trunc;

        hdr = EXTRACT_32BITS(bp);
        bp += sizeof(hdr);
        l -= sizeof(hdr);
        len -= sizeof(hdr);

        if (vflag) {
                index = (hdr & ERSPAN2_INDEX_MASK) >> ERSPAN2_INDEX_SHIFT;
                printf(" index %u", index);
        }

        printf(": ");
        ether_tryprint(bp, len, 0);
        return;

trunc:
        printf(" [|erspan]");
}

void
gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen,
    const u_char *bp, u_int len)
{
        switch (af) {
        case GRESRE_IP:
                printf(" (rtaf=ip");
                gre_sre_ip_print(sreoff, srelen, bp, len);
                printf(")");
                break;
        case GRESRE_ASN:
                printf(" (rtaf=asn");
                gre_sre_asn_print(sreoff, srelen, bp, len);
                printf(")");
                break;
        default:
                printf(" (rtaf=0x%x)", af);
        }
}
void
gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
{
        struct in_addr a;
        const u_char *up = bp;

        if (sreoff & 3) {
                printf(" badoffset=%u", sreoff);
                return;
        }
        if (srelen & 3) {
                printf(" badlength=%u", srelen);
                return;
        }
        if (sreoff >= srelen) {
                printf(" badoff/len=%u/%u", sreoff, srelen);
                return;
        }

        for (;;) {
                if (len < 4 || srelen == 0)
                        return;

                memcpy(&a, bp, sizeof(a));
                printf(" %s%s",
                    ((bp - up) == sreoff) ? "*" : "",
                    inet_ntoa(a));

                bp += 4;
                len -= 4;
                srelen -= 4;
        }
}

void
gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
{
        const u_char *up = bp;

        if (sreoff & 1) {
                printf(" badoffset=%u", sreoff);
                return;
        }
        if (srelen & 1) {
                printf(" badlength=%u", srelen);
                return;
        }
        if (sreoff >= srelen) {
                printf(" badoff/len=%u/%u", sreoff, srelen);
                return;
        }

        for (;;) {
                if (len < 2 || srelen == 0)
                        return;

                printf(" %s%x",
                    ((bp - up) == sreoff) ? "*" : "",
                    EXTRACT_16BITS(bp));

                bp += 2;
                len -= 2;
                srelen -= 2;
        }
}

/*
 * - RFC 7348 Virtual eXtensible Local Area Network (VXLAN)
 * - draft-ietf-nvo3-vxlan-gpe-08 Generic Protocol Extension for VXLAN
 */

struct vxlan_header {
        uint16_t        flags;
#define VXLAN_VER               0x3000  /* GPE */
#define VXLAN_VER_0             0x0000
#define VXLAN_I                 0x0800  /* Instance Bit */
#define VXLAN_P                 0x0400  /* GPE Next Protocol */
#define VXLAN_B                 0x0200  /* GPE BUM Traffic */
#define VXLAN_O                 0x0100  /* GPE OAM Flag */
        uint8_t         reserved;
        uint8_t         next_proto;     /* GPE */
#define VXLAN_PROTO_RESERVED    0x00
#define VXLAN_PROTO_IPV4        0x01
#define VXLAN_PROTO_IPV6        0x02
#define VXLAN_PROTO_ETHERNET    0x03
#define VXLAN_PROTO_NSH         0x04
#define VXLAN_PROTO_MPLS        0x05
#define VXLAN_PROTO_VBNG        0x07
#define VXLAN_PROTO_GBP         0x80
#define VXLAN_PROTO_IOAM        0x82
        uint32_t        vni;
#define VXLAN_VNI_SHIFT         8
#define VXLAN_VNI_MASK          (0xffffffU << VXLAN_VNI_SHIFT)
#define VXLAN_VNI_RESERVED      (~VXLAN_VNI_MASK)
};

void
vxlan_print(const u_char *p, u_int length)
{
        const struct vxlan_header *vh;
        uint16_t flags, ver;
        uint8_t proto = VXLAN_PROTO_ETHERNET;
        int l = snapend - p;

        printf("VXLAN");

        if (l < sizeof(*vh))
                goto trunc;
        if (length < sizeof(*vh)) {
                printf(" ip truncated");
                return;
        }

        vh = (const struct vxlan_header *)p;

        p += sizeof(*vh);
        length -= sizeof(*vh);

        flags = ntohs(vh->flags);
        ver = flags & VXLAN_VER;
        if (ver != VXLAN_VER_0) {
                printf(" unknown version %u", ver >> 12);
                return;
        }

        if (flags & VXLAN_I) {
                uint32_t vni = (htonl(vh->vni) & VXLAN_VNI_MASK) >>
                    VXLAN_VNI_SHIFT;
                printf(" vni %u", vni);
        }

        if (flags & VXLAN_P)
                proto = vh->next_proto;

        if (flags & VXLAN_B)
                printf(" BUM");

        if (flags & VXLAN_O) {
                printf(" OAM (proto 0x%x, len %u)", proto, length);
                return;
        }

        printf(": ");

        switch (proto) {
        case VXLAN_PROTO_RESERVED:
                printf("Reserved");
                break;
        case VXLAN_PROTO_IPV4:
                ip_print(p, length);
                break;
        case VXLAN_PROTO_IPV6:
                ip6_print(p, length);
                break;
        case VXLAN_PROTO_ETHERNET:
                ether_tryprint(p, length, 0);
                break;
        case VXLAN_PROTO_NSH:
                nsh_print(p, length);
                break;
        case VXLAN_PROTO_MPLS:
                mpls_print(p, length);
                break;

        default:
                printf("Unassigned proto 0x%x", proto);
                break;
        }

        return;
trunc:
        printf(" [|vxlan]");
}

/*
 * Geneve: Generic Network Virtualization Encapsulation
 * draft-ietf-nvo3-geneve-16
 */

struct geneve_header {
        uint16_t        flags;
#define GENEVE_VER_SHIFT        14
#define GENEVE_VER_MASK         (0x3U << GENEVE_VER_SHIFT)
#define GENEVE_VER_0            (0x0U << GENEVE_VER_SHIFT)
#define GENEVE_OPT_LEN_SHIFT    8
#define GENEVE_OPT_LEN_MASK     (0x3fU << GENEVE_OPT_LEN_SHIFT)
#define GENEVE_OPT_LEN_UNITS    4
#define GENEVE_O                0x0080  /* Control packet */
#define GENEVE_C                0x0040  /* Critical options present */
        uint16_t                protocol;
        uint32_t        vni;
#define GENEVE_VNI_SHIFT        8
#define GENEVE_VNI_MASK         (0xffffffU << GENEVE_VNI_SHIFT)
#define GENEVE_VNI_RESERVED     (~GENEVE_VNI_MASK)
};

struct geneve_option {
        uint16_t        class;
        uint8_t         type;
        uint8_t         flags;
#define GENEVE_OPTION_LENGTH_SHIFT      0
#define GENEVE_OPTION_LENGTH_MASK       (0x1fU << GENEVE_OPTION_LENGTH_SHIFT)
};

static void
geneve_options_print(const u_char *p, u_int l)
{
        if (l == 0)
                return;

        do {
                struct geneve_option *go;
                unsigned int len, i;

                if (l < sizeof(*go))
                        goto trunc;

                go = (struct geneve_option *)p;
                p += sizeof(*go);
                l -= sizeof(*go);

                printf("\n\toption class %u type %u", ntohs(go->class),
                    go->type);

                len = (go->flags & GENEVE_OPTION_LENGTH_MASK) >>
                    GENEVE_OPTION_LENGTH_SHIFT;
                if (len > 0) {
                        printf(":");
                        for (i = 0; i < len; i++) {
                                uint32_t w;

                                if (l < sizeof(w))
                                        goto trunc;

                                w = EXTRACT_32BITS(p);
                                p += sizeof(w);
                                l -= sizeof(w);

                                printf(" %08x", w);
                        }
                }
        } while (l > 0);

        return;
trunc:
        printf("[|geneve option]");
}

void
geneve_print(const u_char *p, u_int length)
{
        const struct geneve_header *gh;
        uint16_t flags, ver, optlen, proto;
        uint32_t vni;
        int l = snapend - p;

        printf("geneve");

        if (l < sizeof(*gh))
                goto trunc;
        if (length < sizeof(*gh)) {
                printf(" ip truncated");
                return;
        }

        gh = (const struct geneve_header *)p;

        p += sizeof(*gh);
        l -= sizeof(*gh);
        length -= sizeof(*gh);

        flags = ntohs(gh->flags);
        ver = flags & GENEVE_VER_MASK;
        if (ver != GENEVE_VER_0) {
                printf(" unknown version %u", ver >> GENEVE_VER_SHIFT);
                return;
        }

        vni = (htonl(gh->vni) & GENEVE_VNI_MASK) >> GENEVE_VNI_SHIFT;
        printf(" vni %u", vni);

        if (flags & GENEVE_O)
                printf(" Control");

        if (flags & GENEVE_C)
                printf(" Critical");

        optlen = (flags & GENEVE_OPT_LEN_MASK) >> GENEVE_OPT_LEN_SHIFT;
        optlen *= GENEVE_OPT_LEN_UNITS;

        if (l < optlen)
                goto trunc;
        if (length < optlen) {
                printf(" ip truncated");
                return;
        }

        if (optlen > 0)
                geneve_options_print(p, optlen);

        p += optlen;
        length -= optlen;

        printf("\n    ");

        proto = ntohs(gh->protocol);
        switch (proto) {
        case ETHERTYPE_IP:
                ip_print(p, length);
                break;
        case ETHERTYPE_IPV6:
                ip6_print(p, length);
                break;
        case ETHERTYPE_MPLS:
        case ETHERTYPE_MPLS_MCAST:
                mpls_print(p, length);
                break;
        case ETHERTYPE_TRANSETHER:
                ether_tryprint(p, length, 0);
                break;

        default:
                printf("geneve-protocol-0x%x", proto);
                break;
        }

        return;
trunc:
        printf(" [|geneve]");
}