/*-
* Copyright (c) 2014-2020 Mindaugas Rasiukevicius <rmind at netbsd org>
* Copyright (c) 2010-2014 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This material is based upon work partially supported by The
* NetBSD Foundation under a contract with Mindaugas Rasiukevicius.
*
* 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 NETBSD FOUNDATION, INC. 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 THE FOUNDATION 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.
*/

/*
* Connection key -- is an n-tuple structure encoding the address length,
* layer 3 protocol, source and destination addresses and ports (or other
* protocol IDs) and some configurable elements (see below).
*
* Key layout
*
*      The single key is formed out of 32-bit integers.  The layout is
*      as follows (first row -- fields, second row -- number of bits):
*
*      | alen | proto |  ckey  | src-id | dst-id | src-addr | dst-addr |
*      +------+-------+--------+--------+--------+----------+----------+
*      |   4  |   8   |   20   |   16   |   16   |  32-128  |  32-128  |
*
*      The source and destination are inverted if the key is for the
*      backwards stream (NPF_FLOW_BACK).  The address length depends on
*      the 'alen' field.  The length is in words and is either 1 or 4,
*      meaning 4 or 16 in bytes.
*
*      The 20-bit configurable key area ('ckey') is for the optional
*      elements which may be included or excluded by the user.  It has
*      the following layout:
*
*      | direction | interface-id |
*      +-----------+--------------+
*      |     2     |      18      |
*
*      Note: neither direction nor interface ID cannot be zero; we rely
*      on this by reserving the zero 'ckey' value to for the case when
*      these checks are not applicable.
*
* Embedding in the connection structure (npf_conn_t)
*
*      Two keys are stored in the npf_conn_t::c_keys[] array, which is
*      variable-length, depending on whether the keys store IPv4 or IPv6
*      addresses.  The length of the first key determines the position
*      of the second key.
*
* WARNING: the keys must be immutable while they are in conndb.
*/

#ifdef _KERNEL
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: npf_connkey.c,v 1.2 2020/05/30 14:16:56 rmind Exp $");

#include <sys/param.h>
#include <sys/types.h>
#endif

#define __NPF_CONN_PRIVATE
#include "npf_conn.h"
#include "npf_impl.h"

unsigned
npf_connkey_setkey(npf_connkey_t *key, unsigned alen, unsigned proto,
   const void *ipv, const uint16_t *id, const npf_flow_t flow)
{
       const npf_addr_t * const *ips = ipv;
       uint32_t *k = key->ck_key;
       unsigned isrc, idst;

       if (__predict_true(flow == NPF_FLOW_FORW)) {
               isrc = NPF_SRC, idst = NPF_DST;
       } else {
               isrc = NPF_DST, idst = NPF_SRC;
       }

       /*
        * See the key layout explanation above.
        */
       KASSERT((alen >> 2) <= 0xf && proto <= 0xff);
       k[0] = ((uint32_t)(alen >> 2) << 28) | (proto << 20);
       k[1] = ((uint32_t)id[isrc] << 16) | id[idst];

       if (__predict_true(alen == sizeof(in_addr_t))) {
               k[2] = ips[isrc]->word32[0];
               k[3] = ips[idst]->word32[0];
               return 4 * sizeof(uint32_t);
       } else {
               const unsigned nwords = alen >> 2;
               memcpy(&k[2], ips[isrc], alen);
               memcpy(&k[2 + nwords], ips[idst], alen);
               return (2 + (nwords * 2)) * sizeof(uint32_t);
       }
}

void
npf_connkey_getkey(const npf_connkey_t *key, unsigned *alen, unsigned *proto,
   npf_addr_t *ips, uint16_t *id)
{
       const uint32_t *k = key->ck_key;

       /*
        * See the key layout explanation above.
        */

       *alen = (k[0] >> 28) << 2;
       *proto = (k[0] >> 16) & 0xff;
       id[NPF_SRC] = k[1] >> 16;
       id[NPF_DST] = k[1] & 0xffff;

       switch (*alen) {
       case sizeof(struct in6_addr):
       case sizeof(struct in_addr):
               memcpy(&ips[NPF_SRC], &k[2], *alen);
               memcpy(&ips[NPF_DST], &k[2 + ((unsigned)*alen >> 2)], *alen);
               return;
       default:
               KASSERT(0);
       }
}

static inline void
npf_connkey_setckey(npf_connkey_t *key, unsigned ifid, unsigned di)
{
       if (ifid) {
               /*
                * Interface ID: the lower 18 bits of the 20-bit 'ckey'.
                * Note: the interface ID cannot be zero.
                */
               CTASSERT(NPF_MAX_IFMAP < (1U << 18));
               key->ck_key[0] |= ifid;
       }
       if (di) {
               /*
                * Direction: The highest 2 bits of the 20-bit 'ckey'.
                * Note: we rely on PFIL_IN and PFIL_OUT definitions.
                */
               CTASSERT(PFIL_IN == 0x1 || PFIL_OUT == 0x2);
               KASSERT((di & ~PFIL_ALL) == 0);
               key->ck_key[0] |= ((uint32_t)di << 18);
       }
}

static void
npf_connkey_getckey(const npf_connkey_t *key, unsigned *ifid, unsigned *di)
{
       const uint32_t * const k = key->ck_key;

       *ifid = k[0] & ((1U << 20) - 1);
       *di = (k[0] >> 18) & PFIL_ALL;
}

/*
* npf_conn_adjkey: adjust the connection key by setting the address/port.
*
* => The 'which' must either be NPF_SRC or NPF_DST.
*/
void
npf_conn_adjkey(npf_connkey_t *key, const npf_addr_t *naddr,
   const uint16_t id, const unsigned which)
{
       const unsigned alen = NPF_CONNKEY_ALEN(key);
       uint32_t * const k = key->ck_key;
       uint32_t *addr = &k[2 + ((alen >> 2) * which)];

       KASSERT(which == NPF_SRC || which == NPF_DST);
       KASSERT(alen > 0);
       memcpy(addr, naddr, alen);

       if (id) {
               const uint32_t oid = k[1];
               const unsigned shift = 16 * !which;
               const uint32_t mask = 0xffff0000 >> shift;
               k[1] = ((uint32_t)id << shift) | (oid & mask);
       }
}

static unsigned
npf_connkey_copy(const npf_connkey_t *skey, npf_connkey_t *dkey, bool invert)
{
       const unsigned klen = NPF_CONNKEY_LEN(skey);
       const uint32_t *sk = skey->ck_key;
       uint32_t *dk = dkey->ck_key;

       if (invert) {
               const unsigned alen = NPF_CONNKEY_ALEN(skey);
               const unsigned nwords = alen >> 2;

               dk[0] = sk[1];
               dk[1] = (sk[1] >> 16) | (sk[1] << 16);
               memcpy(&dk[2], &sk[2 + nwords], alen);
               memcpy(&dk[2 + nwords], &sk[2], alen);
       } else {
               memcpy(dk, sk, klen);
       }
       return klen;
}

/*
* npf_conn_conkey: construct a key for the connection lookup.
*
* => Returns the key length in bytes or zero on failure.
*/
unsigned
npf_conn_conkey(const npf_cache_t *npc, npf_connkey_t *key,
   const unsigned di, const npf_flow_t flow)
{
       const npf_conn_params_t *params = npc->npc_ctx->params[NPF_PARAMS_CONN];
       const nbuf_t *nbuf = npc->npc_nbuf;
       const unsigned proto = npc->npc_proto;
       const unsigned alen = npc->npc_alen;
       const struct tcphdr *th;
       const struct udphdr *uh;
       uint16_t id[2] = { 0, 0 };
       unsigned ret;

       if (npc->npc_ckey) {
               /*
                * Request to override the connection key.
                */
               const bool invert = flow != NPF_FLOW_FORW;
               return npf_connkey_copy(npc->npc_ckey, key, invert);
       }

       switch (proto) {
       case IPPROTO_TCP:
               KASSERT(npf_iscached(npc, NPC_TCP));
               th = npc->npc_l4.tcp;
               id[NPF_SRC] = th->th_sport;
               id[NPF_DST] = th->th_dport;
               break;
       case IPPROTO_UDP:
               KASSERT(npf_iscached(npc, NPC_UDP));
               uh = npc->npc_l4.udp;
               id[NPF_SRC] = uh->uh_sport;
               id[NPF_DST] = uh->uh_dport;
               break;
       case IPPROTO_ICMP:
               if (npf_iscached(npc, NPC_ICMP_ID)) {
                       const struct icmp *ic = npc->npc_l4.icmp;
                       id[NPF_SRC] = ic->icmp_id;
                       id[NPF_DST] = ic->icmp_id;
                       break;
               }
               return 0;
       case IPPROTO_ICMPV6:
               if (npf_iscached(npc, NPC_ICMP_ID)) {
                       const struct icmp6_hdr *ic6 = npc->npc_l4.icmp6;
                       id[NPF_SRC] = ic6->icmp6_id;
                       id[NPF_DST] = ic6->icmp6_id;
                       break;
               }
               return 0;
       default:
               /* Unsupported protocol. */
               return 0;
       }

       ret = npf_connkey_setkey(key, alen, proto, npc->npc_ips, id, flow);
       npf_connkey_setckey(key,
           params->connkey_interface ? nbuf->nb_ifid : 0,
           params->connkey_direction ? (di & PFIL_ALL) : 0);
       return ret;
}

/*
* npf_conn_getforwkey: get the address to the "forwards" key.
*/
npf_connkey_t *
npf_conn_getforwkey(npf_conn_t *conn)
{
       return (void *)&conn->c_keys[0];
}

/*
* npf_conn_getbackkey: get the address to the "backwards" key.
*
* => It depends on the address length.
*/
npf_connkey_t *
npf_conn_getbackkey(npf_conn_t *conn, unsigned alen)
{
       const unsigned off = 2 + ((alen * 2) >> 2);
       KASSERT(off == NPF_CONNKEY_V4WORDS || off == NPF_CONNKEY_V6WORDS);
       return (void *)&conn->c_keys[off];
}

/*
* Connection key exporting/importing.
*/

nvlist_t *
npf_connkey_export(npf_t *npf, const npf_connkey_t *key)
{
       unsigned alen, proto, ifid, di;
       npf_addr_t ips[2];
       uint16_t ids[2];
       nvlist_t *key_nv;

       key_nv = nvlist_create(0);

       npf_connkey_getkey(key, &alen, &proto, ips, ids);
       nvlist_add_number(key_nv, "proto", proto);
       nvlist_add_number(key_nv, "sport", ids[NPF_SRC]);
       nvlist_add_number(key_nv, "dport", ids[NPF_DST]);
       nvlist_add_binary(key_nv, "saddr", &ips[NPF_SRC], alen);
       nvlist_add_binary(key_nv, "daddr", &ips[NPF_DST], alen);

       npf_connkey_getckey(key, &ifid, &di);
       if (ifid) {
               char ifname[IFNAMSIZ];
               npf_ifmap_copyname(npf, ifid, ifname, sizeof(ifname));
               nvlist_add_string(key_nv, "ifname", ifname);
       }
       if (di) {
               nvlist_add_number(key_nv, "di", di);
       }

       return key_nv;
}

unsigned
npf_connkey_import(npf_t *npf, const nvlist_t *key_nv, npf_connkey_t *key)
{
       npf_addr_t const * ips[2];
       size_t alen1, alen2, proto;
       unsigned ret, di, ifid = 0;
       const char *ifname;
       uint16_t ids[2];

       proto = dnvlist_get_number(key_nv, "proto", 0);
       if (proto >= IPPROTO_MAX) {
               return 0;
       }
       ids[NPF_SRC] = dnvlist_get_number(key_nv, "sport", 0);
       ids[NPF_DST] = dnvlist_get_number(key_nv, "dport", 0);
       ips[NPF_SRC] = dnvlist_get_binary(key_nv, "saddr", &alen1, NULL, 0);
       ips[NPF_DST] = dnvlist_get_binary(key_nv, "daddr", &alen2, NULL, 0);
       if (alen1 == 0 || alen1 > sizeof(npf_addr_t) || alen1 != alen2) {
               return 0;
       }
       ret = npf_connkey_setkey(key, alen1, proto, ips, ids, NPF_FLOW_FORW);
       if (ret == 0) {
               return 0;
       }

       ifname = dnvlist_get_string(key_nv, "ifname", NULL);
       if (ifname && (ifid = npf_ifmap_register(npf, ifname)) == 0) {
               return 0;
       }
       di = dnvlist_get_number(key_nv, "di", 0) & PFIL_ALL;
       npf_connkey_setckey(key, ifid, di);

       return ret;
}

#if defined(DDB) || defined(_NPF_TESTING)

void
npf_connkey_print(const npf_connkey_t *key)
{
       unsigned alen, proto, ifid, di;
       npf_addr_t ips[2];
       uint16_t ids[2];

       npf_connkey_getkey(key, &alen, &proto, ips, ids);
       npf_connkey_getckey(key, &ifid, &di);
       printf("\tkey (ifid %u, di %x)\t", ifid, di);
       printf("%s:%u", npf_addr_dump(&ips[0], alen), ids[0]);
       printf("-> %s:%u\n", npf_addr_dump(&ips[1], alen), ids[1]);
}

#endif

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