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Rework UDP parsing, particularly around IP addresses.

This originally started as trying to put a consistent space between
the UDP header information and the payload parsing, but while doing
that I noticed inconsistent IPv4 vs IPv6 handling.

Apart from the default "srcip.srcport > dstip.dstpor" output, all
the other places that IP addresses were printed assumed IPv4. It
looks like it is possible that udp_print() can be called without
an IP header, which made these blind IPv4 prints turn into NULL
derefs.

This fixes the problem above by only having a single place that
prints the addresses out, and makes sure to get the difference
between IPv4, IPv6 and no IP correct.

This changes how the checksum is calculated. It incrementally builds
the UDP checksum by feeding the IPv4 and v6 addresses in separately,
then using common code for the rest of the pseudo header and actual
payload.

Lastly, this does make printing the space between the UDP header
and its payload consistent. The UDP code is now responsible for
adding a space after itself so the payload parsers don't have to.
They got it wrong in some cases anyway, so this should be a lot
more uniform.

help and ok sthen@

/*	$OpenBSD: print-vqp.c,v 1.8 2018/07/06 05:47:22 dlg Exp $	*/

/*
 * Copyright (c) 2006 Kevin Steves <stevesk@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.
 */

/*
 * VLAN Query Protocol (VQP)
 *
 *    0                   1                   2                   3
 *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |    Version    |    Opcode     | Response Code |  Data Count   |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                         Transaction ID                        |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                            Type (1)                           |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |             Length            |            Data               /
 *   /                                                               /
 *   /                                                               /
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                            Type (n)                           |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |             Length            |            Data               /
 *   /                                                               /
 *   /                                                               /
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * VQP is layered over UDP.  The default destination port is 1589.
 *
 */

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

#include <net/if.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <arpa/inet.h>

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

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

struct vqp_hdr {
	u_char version;
	u_char opcode;
	u_char rcode;
	u_char dcount;
	u_int32_t xid;
};

#define VQP_JOIN			0x01
#define VQP_JOIN_RESPONSE		0x02
#define VQP_RECONFIRM			0x03
#define VQP_RECONFIRM_RESPONSE		0x04

#define VQP_NO_ERROR			0x00
#define VQP_WRONG_VERSION		0x01
#define VQP_INSUFFICIENT_RESOURCES	0x02
#define VQP_DENY			0x03
#define VQP_SHUTDOWN			0x04
#define VQP_WRONG_MGMT_DOMAIN		0x05

/* 4 bytes struct in_addr; IP address of VQP client */
#define VQP_CLIENT_ADDR			0x00000c01
/* string */
#define VQP_PORT_NAME			0x00000c02
/* string */
#define VQP_VLAN_NAME			0x00000c03
/* string; VTP domain if set */
#define VQP_DOMAIN_NAME			0x00000c04
/* ethernet frame */
#define VQP_ETHERNET_FRAME		0x00000c05
/* 6 bytes, mac address */
#define VQP_MAC				0x00000c06
/* 2 bytes? */
#define VQP_UNKNOWN			0x00000c07
/* 6 bytes, mac address */
#define VQP_COOKIE			0x00000c08

static void
vqp_print_opcode(u_int val)
{
	switch (val) {
	case VQP_JOIN:
		printf("Join");
		break;
	case VQP_JOIN_RESPONSE:
		printf("JoinResp");
		break;
	case VQP_RECONFIRM:
		printf("Reconfirm");
		break;
	case VQP_RECONFIRM_RESPONSE:
		printf("ReconfirmResp");
		break;
	default:
		printf("unknown(%x)", val);
		break;
	}
}

static void
vqp_print_rcode(u_int val)
{
	switch (val) {
	case VQP_NO_ERROR:
		printf("NoError");
		break;
	case VQP_WRONG_VERSION:
		printf("WrongVersion");
		break;
	case VQP_INSUFFICIENT_RESOURCES:
		printf("InsufficientResources");
		break;
	case VQP_DENY:
		printf("Deny");
		break;
	case VQP_SHUTDOWN:
		printf("Shutdown");
		break;
	case VQP_WRONG_MGMT_DOMAIN:
		printf("WrongMgmtDomain");
		break;
	default:
		printf("unknown(%x)", val);
		break;
	}
}

static void
print_hex(const u_char *p, u_int len)
{
	while (len--)
		printf("%02x", *p++);
}

static void
vqp_print_type(u_int type, u_int len, const u_char *p)
{
	switch (type) {
	case VQP_CLIENT_ADDR:
		printf(" client:");
		if (len == sizeof(struct in_addr)) {
			struct in_addr in;
			memcpy(&in, p, sizeof in);
			printf("%s", inet_ntoa(in));
		} else
			print_hex(p, len);
		break;
	case VQP_PORT_NAME:
		printf(" port:");
		fn_printn(p, len, NULL);
		break;
	case VQP_VLAN_NAME:
		printf(" vlan:");
		fn_printn(p, len, NULL);
		break;
	case VQP_DOMAIN_NAME:
		printf(" domain:");
		fn_printn(p, len, NULL);
		break;
	case VQP_ETHERNET_FRAME:
		printf(" ethernet:");
		if (vflag > 1)
			print_hex(p, len);
		else if (len >= ETHER_ADDR_LEN * 2) {
			p += ETHER_ADDR_LEN;	/* skip dst mac */
			printf("%s", etheraddr_string(p)); /* src mac */
		} else
			print_hex(p, len);
		break;
	case VQP_MAC:
		printf(" mac:");
		if (len == ETHER_ADDR_LEN)
			printf("%s", etheraddr_string(p));
		else
			print_hex(p, len);
		break;
	case VQP_UNKNOWN:
		printf(" unknown:");
		print_hex(p, len);
		break;
	case VQP_COOKIE:
		printf(" cookie:");
		if (len == ETHER_ADDR_LEN)
			printf("%s", etheraddr_string(p));
		else
			print_hex(p, len);
		break;
	default:
		printf(" unknown(%x/%u)", type, len);
	}
}

void
vqp_print(const u_char *bp, u_int len)
{
	struct vqp_hdr *p = (struct vqp_hdr *)bp;
	u_int dcount;

	TCHECK(p->version);
	printf("VQPv%u", p->version);
	if (p->version != 1)
		return;
	TCHECK(p->opcode);
	printf("-");
	vqp_print_opcode(p->opcode);
	TCHECK(p->rcode);
	printf(" rcode:");
	vqp_print_rcode(p->rcode);
	TCHECK(p->xid);
	printf(" xid:0x%08x", ntohl(p->xid));
	printf(" dcount:%u", p->dcount);
	bp += sizeof(struct vqp_hdr);

	dcount = p->dcount;
	while (vflag && dcount > 0) {
		u_int type, length;

		TCHECK2(bp[0], 6);
		type = EXTRACT_32BITS(bp);
		bp += 4;
		length = EXTRACT_16BITS(bp);
		bp += 2;
		TCHECK2(bp[0], length);
		vqp_print_type(type, length, bp);
		bp += length;
		dcount--;
	}

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