wireshark/epan/ftypes/ftype-ipv6.c

/*
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 2001 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "config.h"

#include <string.h>

#include <ftypes-int.h>
#include <epan/ipv6.h>
#include <epan/addr_resolv.h>
#include <epan/to_str.h>

static void
ipv6_fvalue_set(fvalue_t *fv, const guint8 *value)
{
	memcpy(fv->value.ipv6.addr.bytes, value, FT_IPv6_LEN);
	fv->value.ipv6.prefix = 128;
}

static gboolean
ipv6_from_unparsed(fvalue_t *fv, const char *s, gboolean allow_partial_value _U_, gchar **err_msg)
{
	const char *slash;
	const char *addr_str;
	char *addr_str_to_free = NULL;
	unsigned int nmask_bits;
	fvalue_t *nmask_fvalue;

	/* Look for prefix: Is there a single slash in the string? */
	slash = strchr(s, '/');
	if (slash) {
		/* Make a copy of the string up to but not including the
		 * slash; that's the address portion. */
		addr_str_to_free = wmem_strndup(NULL, s, slash-s);
		addr_str = addr_str_to_free;
	}
	else
		addr_str = s;

	if (!get_host_ipaddr6(addr_str, &(fv->value.ipv6.addr))) {
		if (err_msg != NULL)
			*err_msg = ws_strdup_printf("\"%s\" is not a valid hostname or IPv6 address.", s);
		if (addr_str_to_free)
			wmem_free(NULL, addr_str_to_free);
		return FALSE;
	}

	if (addr_str_to_free)
		wmem_free(NULL, addr_str_to_free);

	/* If prefix */
	if (slash) {
		/* XXX - this is inefficient */
		nmask_fvalue = fvalue_from_unparsed(FT_UINT32, slash+1, FALSE, err_msg);
		if (!nmask_fvalue) {
			return FALSE;
		}
		nmask_bits = fvalue_get_uinteger(nmask_fvalue);
		fvalue_free(nmask_fvalue);

		if (nmask_bits > 128) {
			if (err_msg != NULL) {
				*err_msg = ws_strdup_printf("Prefix in a IPv6 address should be <= 128, not %u",
						nmask_bits);
			}
			return FALSE;
		}
		fv->value.ipv6.prefix = nmask_bits;
	} else {
		/* Not CIDR; mask covers entire address. */
		fv->value.ipv6.prefix = 128;
	}

	return TRUE;
}

static char *
ipv6_to_repr(wmem_allocator_t *scope, const fvalue_t *fv, ftrepr_t rtype _U_, int field_display _U_)
{
	return ip6_to_str(scope, &(fv->value.ipv6.addr));
}

static gpointer
value_get(fvalue_t *fv)
{
	return fv->value.ipv6.addr.bytes;
}

static const guint8 bitmasks[9] =
	{ 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff };

static int
cmp_order(const fvalue_t *fv_a, const fvalue_t *fv_b)
{
	const ipv6_addr_and_prefix *a = &(fv_a->value.ipv6);
	const ipv6_addr_and_prefix *b = &(fv_b->value.ipv6);
	guint32	prefix;
	int pos = 0;

	prefix = MIN(a->prefix, b->prefix);	/* MIN() like IPv4 */
	prefix = MIN(prefix, 128);		/* sanitize, max prefix is 128 */

	while (prefix >= 8) {
		gint byte_a = (gint) (a->addr.bytes[pos]);
		gint byte_b = (gint) (b->addr.bytes[pos]);

		if (byte_a != byte_b)
			return byte_a - byte_b;

		prefix -= 8;
		pos++;
	}

	if (prefix != 0) {
		gint byte_a = (gint) (a->addr.bytes[pos] & (bitmasks[prefix]));
		gint byte_b = (gint) (b->addr.bytes[pos] & (bitmasks[prefix]));

		if (byte_a != byte_b)
			return byte_a - byte_b;
	}
	return 0;
}

static gboolean
cmp_bitwise_and(const fvalue_t *fv_a, const fvalue_t *fv_b)
{
	const ipv6_addr_and_prefix *a = &(fv_a->value.ipv6);
	const ipv6_addr_and_prefix *b = &(fv_b->value.ipv6);
	guint32	prefix;
	int pos = 0;

	prefix = MIN(a->prefix, b->prefix);	/* MIN() like in IPv4 */
	prefix = MIN(prefix, 128);			/* sanitize, max prefix is 128 */

	while (prefix >= 8) {
		if (a->addr.bytes[pos] & b->addr.bytes[pos])
			return TRUE;

		prefix -= 8;
		pos++;
	}

	if (prefix != 0) {
		guint8 byte_a = (a->addr.bytes[pos] & (bitmasks[prefix]));
		guint8 byte_b = (b->addr.bytes[pos] & (bitmasks[prefix]));

		if (byte_a & byte_b)
			return TRUE;
	}
	return FALSE;
}

static void
slice(fvalue_t *fv, GByteArray *bytes, guint offset, guint length)
{
	guint8* data;

	data = fv->value.ipv6.addr.bytes + offset;

	g_byte_array_append(bytes, data, length);
}

void
ftype_register_ipv6(void)
{
	static ftype_t ipv6_type = {
		FT_IPv6,			/* ftype */
		"FT_IPv6",			/* name */
		"IPv6 address",			/* pretty_name */
		FT_IPv6_LEN,			/* wire_size */
		NULL,				/* new_value */
		NULL,				/* free_value */
		ipv6_from_unparsed,		/* val_from_unparsed */
		NULL,				/* val_from_string */
		NULL,				/* val_from_charconst */
		ipv6_to_repr,			/* val_to_string_repr */

		{ .set_value_bytes = ipv6_fvalue_set },	/* union set_value */
		{ .get_value_ptr = value_get },		/* union get_value */

		cmp_order,
		cmp_bitwise_and,
		NULL, 				/* XXX, cmp_contains, needed? ipv4 doesn't support it */
		NULL,				/* cmp_matches */

		NULL,
		slice,
	};

	ftype_register(FT_IPv6, &ipv6_type);
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 8
 * tab-width: 8
 * indent-tabs-mode: t
 * End:
 *
 * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 * :indentSize=8:tabSize=8:noTabs=false:
 */