/*-
 * Copyright (c) 2013-2015 Varnish Software AS
 * All rights reserved.
 *
 * Author: Poul-Henning Kamp <phk@phk.freebsd.dk>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * 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 AND CONTRIBUTORS ``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 AUTHOR OR CONTRIBUTORS 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.
 *
 * Struct sockaddr_* is not even close to a convenient API.
 *
 * These functions try to mitigate the madness, at the cost of actually
 * knowing something about address families.
 */

#include "config.h"

#include <string.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/types.h>
#include <netinet/in.h>

#include "vdef.h"
#include "vas.h"
#include "vsa.h"
#include "miniobj.h"

/*
 * Struct sockaddr{|_in|_in6|_storage} is absolutely the worst data
 * structure I have ever seen gold-plated in international standards.
 *
 * Network addresses have multiple different forms, many fewer today
 * than in last century, but imagine that in addition to IPv4 and IPv6
 * we had 40 other protocols.  Actually, you don't need to imagine that
 * just count the AF_* macros in /usr/include/sys/socket.h.
 *
 * So what do we pass the kernel API for an address to bind(2), connect(2) &
 * listen(2) etc. etc ?
 *
 * We could define a struct which is big enough to hold any and all
 * of these addresses.  That would make it a fixed size argument.
 * obviously the struct would have to be something like:
 *	struct bla {
 *		int family;
 *		char address[MAX_ADDR_LEN];
 *	}
 * and MAX_ADDR_LEN would have to be quite large, 128 byte or so.
 *
 * Back in last century that was TOTALLY unacceptable waste of space.
 *
 * The way which was chosen instead, was to make a "generic" address,
 * and have per protocol "specific" addresses, and pass the length
 * argument explicitly to the KPI functions.
 *
 * The generic address was called "struct sockaddr", and the specific
 * were called "struct sockaddr_${whatever}".  All of these must have
 * a "family" field as first element, so the kernel can figure out
 * which protocol it is.
 *
 * The generic struct sockaddr was made big enough for all protocols
 * supported in the kernel, so it would have different sizes depending
 * on your machine and kernel configuration.
 *
 * However, that allowed you to write protocol-agnostic programs, by
 * using "struct sockaddr" throughout, and relying on libray APIs for
 * things like name to address (and vice versa) resolution, and since
 * nobody were in the business of shipping random UNIX binaries around
 * the lack of binary portability didn't matter.
 *
 * Along the way the BSD people figured out that it was a bother
 * to carry the length argument separately, and added that to the
 * format of sockaddr, but other groups found this unclean, as
 * the length was already an explicit parameter.
 *
 * The net result of this is that your "portable" code, must take
 * care to handle the "sa_len" member on kernels which have it,
 * while still tracking the separate length argument for all other
 * kernels.
 *
 * Needless to say, there were no neat #define to tell you which
 * was which, so each programmer found a different heuristic to
 * decide, often not understanding it fully, which caused the kind
 * of portability issues which lead to the autocrap tools.
 *
 * Then all the other protocols died, we were left with IP and
 * life were good, the dot-com madness multiplied the IT-business
 * by a factor 1000, by making any high-school student who had
 * programmed PERL for 6 weeks a "senior web-programmer".
 *
 * Next IPv6 happened, in a rush even, (no seriously, I'm not kidding!),
 * and since IPv6 addresses were HUGE, like 16 bytes HUGE, the generic
 * struct sockaddr was not increased in size.
 *
 * At least "not yet", because it would break all the shitty code written
 * by the dot-com generation.
 *
 * Nobody used IPv6 anyway so that didn't matter that much.
 *
 * Then people actually started using IPv6 and its struct sockaddr_in6,
 * and realized that all the code which used "struct sockaddr" to allocate
 * space at compile time were broken.
 *
 * Some people took to using sockaddr_in6, since that was known to
 * be big enough for both IPv4 and IPv6, but "purist" found that
 * ugly and "prone to future trouble".
 *
 * So instead they came up with a "clean solution":  The added
 * "struct sockaddr_storage" which is defined to be "Large enough
 * to accommodate all supported protocol-specific address structures".
 *
 * Since we cannot possibly know what zany protocols will exist in
 * the future, and since some people think that we will add future
 * protocols, while retaining ABI compatibility, (totally overlooking
 * the fact that no code for name-resolution supports that) it is
 * usually defined so it can cope with 128 byte addresses.
 *
 * Does that ring a bell ?
 *
 * Only, not quite:  Remember that all APIs require you to track
 * the address and the length separately, so you only get the
 * size of the specific protocols sockaddr_${whatever} from API
 * functions, not a full sockaddr_storage, and besides the
 * prototype for the KPI is still "struct sockaddr *", so you
 * cannot gain C type-safety back by using sockaddr_storage
 * as the "generic network address" type.
 *
 * So we have come full circle, while causing maximum havoc along
 * the way and for the forseeable future.
 *
 * Do I need to tell you that static code analysis tools have a
 * really hard time coping with this, and that they give a lot of
 * false negatives which confuse people ?
 *
 * I have decided to try to contain this crap in this single
 * source-file, with only minimum leakage into the rest of Varnish,
 * which will only know of pointers to "struct suckaddr", the naming
 * of which is my of the historical narrative above.
 *
 * And you don't need to take my word for this, you can see it all
 * in various #include files on your own system.   If you are on
 * a Solaris derivative, don't miss the beautiful horror hidden in the
 * variant definition of IPv6 addresses between kernel and userland.
 *
 */

struct suckaddr {
	unsigned			magic;
#define SUCKADDR_MAGIC			0x4b1e9335
	union {
		struct sockaddr		sa;
		struct sockaddr_in	sa4;
		struct sockaddr_in6	sa6;
	} u;
};

const size_t vsa_suckaddr_len = sizeof(struct suckaddr);

/*
 * Bogus IPv4 address 0.0.0.0:0 to be used for VCL *.ip variables when the
 * "real" address is not IP (such as UDS addresses).
 */
static struct suckaddr bogo_ip_vsa;
const struct suckaddr *bogo_ip = &bogo_ip_vsa;
/* same in IPv6 */
static struct suckaddr bogo_ip6_vsa;
const struct suckaddr *bogo_ip6 = &bogo_ip6_vsa;

void
VSA_Init(void)
{
	AN(VSA_BuildFAP(&bogo_ip_vsa, PF_INET, NULL, 0, NULL, 0));
	AN(VSA_BuildFAP(&bogo_ip6_vsa, PF_INET6, NULL, 0, NULL, 0));
}

/*
 * This VRT interface is for the VCC generated ACL code, which needs
 * to know the address family and a pointer to the actual address.
 */

int
VSA_GetPtr(const struct suckaddr *sua, const unsigned char ** dst)
{

	AN(dst);
	if (sua == NULL)
		return (-1);
	CHECK_OBJ_NOTNULL(sua, SUCKADDR_MAGIC);

	switch (sua->u.sa.sa_family) {
	case PF_INET:
		assert(sua->u.sa.sa_family == sua->u.sa4.sin_family);
		*dst = (const unsigned char *)&sua->u.sa4.sin_addr;
		return (sua->u.sa4.sin_family);
	case PF_INET6:
		assert(sua->u.sa.sa_family == sua->u.sa6.sin6_family);
		*dst = (const unsigned char *)&sua->u.sa6.sin6_addr;
		return (sua->u.sa6.sin6_family);
	default:
		*dst = NULL;
		return (-1);
	}
}

/*
 * Return the size of a struct sockaddr in a struck suckaddr
 * or 0 if unknown family
 */
static inline
socklen_t sua_len(const struct sockaddr *sa)
{

	switch (sa->sa_family) {
	case PF_INET:
		return (sizeof(struct sockaddr_in));
	case PF_INET6:
		return (sizeof(struct sockaddr_in6));
	case AF_UNIX:
		return (sizeof(struct sockaddr_un));
	default:
		return (0);
	}
}

/*
 * Malloc a suckaddr from a sockaddr of some kind.
 */

const struct suckaddr *
VSA_Malloc(const void *s, unsigned  sal)
{

	return (VSA_Build(NULL, s, sal));
}

/*
 * 'd' SHALL point to vsa_suckaddr_len aligned bytes of storage
 *
 * fam: address family
 * a / al : address and length
 * p / pl : port and length
 *
 * NULL or 0 length argument are ignored.
 * argument of the wrong length are an error (NULL return value, EINVAL)
 */
const struct suckaddr *
VSA_BuildFAP(void *d, sa_family_t fam, const void *a, unsigned al,
	    const void *p, unsigned pl)
{
	struct sockaddr_in sin4;
	struct sockaddr_in6 sin6;

	switch (fam) {
	case PF_INET:
		memset(&sin4, 0, sizeof sin4);
		sin4.sin_family = fam;
		if (a != NULL && al > 0) {
			if (al != sizeof(sin4.sin_addr))
				break;
			memcpy(&sin4.sin_addr, a, al);
		}
		if (p != NULL && pl > 0) {
			if (pl != sizeof(sin4.sin_port))
				break;
			memcpy(&sin4.sin_port, p, pl);
		}
		return (VSA_Build(d, &sin4, sizeof sin4));
	case PF_INET6:
		memset(&sin6, 0, sizeof sin6);
		sin6.sin6_family = fam;
		if (a != NULL && al > 0) {
			if (al != sizeof(sin6.sin6_addr))
				break;
			memcpy(&sin6.sin6_addr, a, al);
		}
		if (p != NULL && pl > 0) {
			if (pl != sizeof(sin6.sin6_port))
				break;
			memcpy(&sin6.sin6_port, p, pl);
		}
		return (VSA_Build(d, &sin6, sizeof sin6));
	default:
		errno = EAFNOSUPPORT;
		return (NULL);
	}
	errno = EINVAL;
	return (NULL);
}

const struct suckaddr *
VSA_Build(void *d, const void *s, unsigned sal)
{
	struct suckaddr *sua;
	const struct sockaddr *sa = s;
	unsigned l;	// for flexelint

	AN(s);
	l = sua_len(sa);
	if (l == 0 || l != sal)
		return (NULL);

	if (d == NULL) {
		d = malloc(vsa_suckaddr_len);
		AN(d);
	}

	sua = d;

	INIT_OBJ(sua, SUCKADDR_MAGIC);
	switch (l) {
	case sizeof sua->u.sa4:
		memcpy(&sua->u.sa4, s, l);
		break;
	case sizeof sua->u.sa6:
		memcpy(&sua->u.sa6, s, l);
		break;
	default:
		WRONG("VSA protocol vs. size");
	}
#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
	sua->u.sa.sa_len = (unsigned char)l;
#endif
	return (sua);
}

const void *
VSA_Get_Sockaddr(const struct suckaddr *sua, socklen_t *slp)
{
	socklen_t sl;

	CHECK_OBJ_NOTNULL(sua, SUCKADDR_MAGIC);
	AN(slp);
	sl = sua_len(&sua->u.sa);
	if (sl == 0)
		return (NULL);
	*slp = sl;
	return (&sua->u.sa);
}

int
VSA_Get_Proto(const struct suckaddr *sua)
{

	CHECK_OBJ_NOTNULL(sua, SUCKADDR_MAGIC);
	return (sua->u.sa.sa_family);
}

int
VSA_Sane(const struct suckaddr *sua)
{
	return (VALID_OBJ(sua, SUCKADDR_MAGIC) && sua_len(&sua->u.sa) != 0);
}

int
VSA_Compare(const struct suckaddr *sua1, const struct suckaddr *sua2)
{

	CHECK_OBJ_NOTNULL(sua1, SUCKADDR_MAGIC);
	CHECK_OBJ_NOTNULL(sua2, SUCKADDR_MAGIC);
	return (memcmp(sua1, sua2, vsa_suckaddr_len));
}

int
VSA_Compare_IP(const struct suckaddr *sua1, const struct suckaddr *sua2)
{

	assert(VSA_Sane(sua1));
	assert(VSA_Sane(sua2));

	if (sua1->u.sa.sa_family != sua2->u.sa.sa_family)
		return (-1);

	switch (sua1->u.sa.sa_family) {
	case PF_INET:
		return (memcmp(&sua1->u.sa4.sin_addr,
		    &sua2->u.sa4.sin_addr, sizeof(struct in_addr)));
	case PF_INET6:
		return (memcmp(&sua1->u.sa6.sin6_addr,
		    &sua2->u.sa6.sin6_addr, sizeof(struct in6_addr)));
	default:
		WRONG("Just plain insane");
	}
	NEEDLESS(return (-1));
}

const struct suckaddr *
VSA_Clone(const struct suckaddr *sua)
{
	struct suckaddr *sua2;

	assert(VSA_Sane(sua));
	sua2 = calloc(1, vsa_suckaddr_len);
	XXXAN(sua2);
	memcpy(sua2, sua, vsa_suckaddr_len);
	return (sua2);
}

unsigned
VSA_Port(const struct suckaddr *sua)
{

	CHECK_OBJ_NOTNULL(sua, SUCKADDR_MAGIC);
	switch (sua->u.sa.sa_family) {
	case PF_INET:
		return (ntohs(sua->u.sa4.sin_port));
	case PF_INET6:
		return (ntohs(sua->u.sa6.sin6_port));
	default:
		return (0);
	}
}

#define VSA_getname(which)				\
const struct suckaddr *					\
VSA_get ## which ## name(int fd, void *d, size_t l)	\
{							\
	struct suckaddr *sua;				\
	socklen_t sl;					\
	int r;						\
							\
	AN(d);						\
	if (l != vsa_suckaddr_len) {			\
		errno = EINVAL;				\
		return (NULL);				\
	}						\
							\
	sua = d;					\
							\
	INIT_OBJ(sua, SUCKADDR_MAGIC);			\
	sl = sizeof(sua->u);				\
	r = get ## which ## name(fd, &sua->u.sa, &sl);	\
							\
	return (r == 0 ? sua : NULL);			\
}							\

VSA_getname(sock)
VSA_getname(peer)
#undef VSA_getname

void
VSA_free(const struct suckaddr **vsap)
{
	const struct suckaddr *vsa;

	TAKE_OBJ_NOTNULL(vsa, vsap, SUCKADDR_MAGIC);
	free(TRUST_ME(vsa));
}