/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 1991-2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

#include <sys/types.h>
#include <sys/stream.h>
#include <sys/stropts.h>
#include <sys/tihdr.h>
#include <sys/tiuser.h>
#include <sys/timod.h>

#include <sys/socket.h>
#include <sys/sockio.h>
#include <netinet/in.h>
#include <net/if.h>

#include <inet/common.h>
#include <inet/mib2.h>
#include <inet/ip.h>
#include <netinet/igmp_var.h>
#include <netinet/ip_mroute.h>

#include <arpa/inet.h>

#include <netdb.h>
#include <nss_dbdefs.h>
#include <fcntl.h>
#include <stropts.h>

#include "bootparam_private.h"

typedef struct mib_item_s {
        struct mib_item_s       *next_item;
        long                    group;
        long                    mib_id;
        long                    length;
        char                    *valp;
} mib_item_t;

static void free_itemlist(mib_item_t *);

static mib_item_t *
mibget(int sd)
{
        char                    buf[512];
        int                     flags;
        int                     i, j, getcode;
        struct strbuf           ctlbuf, databuf;
        struct T_optmgmt_req    *tor = (struct T_optmgmt_req *)(void *)buf;
        struct T_optmgmt_ack    *toa = (struct T_optmgmt_ack *)(void *)buf;
        struct T_error_ack      *tea = (struct T_error_ack *)(void *)buf;
        struct opthdr           *req;
        mib_item_t              *first_item = nilp(mib_item_t);
        mib_item_t              *last_item  = nilp(mib_item_t);
        mib_item_t              *temp;

        tor->PRIM_type = T_SVR4_OPTMGMT_REQ;
        tor->OPT_offset = sizeof (struct T_optmgmt_req);
        tor->OPT_length = sizeof (struct opthdr);
        tor->MGMT_flags = T_CURRENT;
        req = (struct opthdr *)&tor[1];
        req->level = MIB2_IP;           /* any MIB2_xxx value ok here */
        req->name  = 0;
        req->len   = 0;

        ctlbuf.buf = buf;
        ctlbuf.len = tor->OPT_length + tor->OPT_offset;
        flags = 0;
        if (putmsg(sd, &ctlbuf, nilp(struct strbuf), flags) == -1) {
                perror("mibget: putmsg(ctl) failed");
                goto error_exit;
        }
        /*
         * each reply consists of a ctl part for one fixed structure
         * or table, as defined in mib2.h.  The format is a T_OPTMGMT_ACK,
         * containing an opthdr structure.  level/name identify the entry,
         * len is the size of the data part of the message.
         */
        req = (struct opthdr *)&toa[1];
        ctlbuf.maxlen = sizeof (buf);
        for (j = 1; ; j++) {
                flags = 0;
                getcode = getmsg(sd, &ctlbuf, nilp(struct strbuf), &flags);
                if (getcode == -1) {
                        perror("mibget getmsg(ctl) failed");
                        if (debug) {
                                msgout("#   level   name    len");
                                i = 0;
                                for (last_item = first_item; last_item;
                                        last_item = last_item->next_item)
                                        msgout("%d  %4ld   %5ld   %ld", ++i,
                                                last_item->group,
                                                last_item->mib_id,
                                                last_item->length);
                        }
                        goto error_exit;
                }
                if ((getcode == 0) &&
                    (ctlbuf.len >= sizeof (struct T_optmgmt_ack))&&
                    (toa->PRIM_type == T_OPTMGMT_ACK) &&
                    (toa->MGMT_flags == T_SUCCESS) &&
                    (req->len == 0)) {
                        if (debug)
                                msgout("mibget getmsg() %d returned EOD "
                                    "(level %lu, name %lu)",
                                    j, req->level, req->name);
                        return (first_item);            /* this is EOD msg */
                }

                if (ctlbuf.len >= sizeof (struct T_error_ack) &&
                    tea->PRIM_type == T_ERROR_ACK) {
                        msgout("mibget %d gives T_ERROR_ACK: "
                            "TLI_error = 0x%lx, UNIX_error = 0x%lx",
                            j, tea->TLI_error, tea->UNIX_error);
                        errno = (tea->TLI_error == TSYSERR)
                                ? tea->UNIX_error : EPROTO;
                        goto error_exit;
                }

                if (getcode != MOREDATA ||
                    ctlbuf.len < sizeof (struct T_optmgmt_ack) ||
                    toa->PRIM_type != T_OPTMGMT_ACK ||
                    toa->MGMT_flags != T_SUCCESS) {
                        msgout("mibget getmsg(ctl) %d returned %d, "
                            "ctlbuf.len = %d, PRIM_type = %ld",
                            j, getcode, ctlbuf.len, toa->PRIM_type);
                        if (toa->PRIM_type == T_OPTMGMT_ACK)
                                msgout("T_OPTMGMT_ACK: MGMT_flags = 0x%lx, "
                                    "req->len = %lu",
                                    toa->MGMT_flags, req->len);
                        errno = ENOMSG;
                        goto error_exit;
                }

                temp = (mib_item_t *)malloc(sizeof (mib_item_t));
                if (!temp) {
                        perror("mibget malloc failed");
                        goto error_exit;
                }
                if (last_item)
                        last_item->next_item = temp;
                else
                        first_item = temp;
                last_item = temp;
                last_item->next_item = nilp(mib_item_t);
                last_item->group = req->level;
                last_item->mib_id = req->name;
                last_item->length = req->len;
                last_item->valp = (char *)malloc(req->len);
                if (debug)
                        msgout(
                        "msg %d:  group = %4ld   mib_id = %5ld   length = %ld",
                                j, last_item->group, last_item->mib_id,
                                last_item->length);

                databuf.maxlen = last_item->length;
                databuf.buf    = last_item->valp;
                databuf.len    = 0;
                flags = 0;
                getcode = getmsg(sd, nilp(struct strbuf), &databuf, &flags);
                if (getcode == -1) {
                        perror("mibget getmsg(data) failed");
                        goto error_exit;
                } else if (getcode != 0) {
                        msgout("xmibget getmsg(data) returned %d, "
                            "databuf.maxlen = %d, databuf.len = %d",
                            getcode, databuf.maxlen, databuf.len);
                        goto error_exit;
                }
        }

error_exit:
        free_itemlist(first_item);
        return (NULL);
}

static void
free_itemlist(mib_item_t *item_list)
{
        mib_item_t      *item;

        while (item_list) {
                item = item_list;
                item_list = item->next_item;
                if (item->valp)
                        free(item->valp);
                free(item);
        }
}

/*
 * If we are a router, return address of interface closest to client.
 * If we are not a router, look through our routing table and return
 * address of "best" router that is on same net as client.
 *
 * We expect the router flag to show up first, followed by interface
 * addr group, followed by the routing table.
 */

in_addr_t
get_ip_route(struct in_addr client_addr)
{
        boolean_t       found;
        mib_item_t      *item_list;
        mib_item_t      *item;
        int             sd;
        mib2_ip_t               *mip;
        mib2_ipAddrEntry_t      *map;
        mib2_ipRouteEntry_t     *rp;
        int                     ip_forwarding = 2;      /* off */
        /* mask of interface used to route to client and best_router */
        struct in_addr          interface_mask;
        /* address of interface used to route to client and best_router */
        struct in_addr          interface_addr;
        /* address of "best router"; i.e. the answer */
        struct in_addr          best_router;

        interface_mask.s_addr = 0L;
        interface_addr.s_addr = 0L;
        best_router.s_addr = 0L;

        /* open a stream to IP */
        sd = open("/dev/ip", O_RDWR);
        if (sd == -1) {
                perror("ip open");
                (void) close(sd);
                msgout("can't open mib stream");
                return (0);
        }

        /* send down a request and suck up all the mib info from IP */
        if ((item_list = mibget(sd)) == nilp(mib_item_t)) {
                msgout("mibget() failed");
                (void) close(sd);
                return (0);
        }

        /*
         * We make three passes through the list of collected IP mib
         * information.  First we figure out if we are a router.  Next,
         * we find which of our interfaces is on the same subnet as
         * the client.  Third, we paw through our own routing table
         * looking for a useful router address.
         */

        /*
         * The general IP group.
         */
        for (item = item_list; item; item = item->next_item) {
                if ((item->group == MIB2_IP) && (item->mib_id == 0)) {
                        /* are we an IP router? */
                        mip = (mib2_ip_t *)(void *)item->valp;
                        ip_forwarding = mip->ipForwarding;
                        break;
                }
        }

        /*
         * The interface group.
         */
        for (item = item_list, found = B_FALSE; item != NULL && !found;
            item = item->next_item) {
                if ((item->group == MIB2_IP) && (item->mib_id == MIB2_IP_20)) {
                        /*
                         * Try to find out which interface is up, configured,
                         * not loopback, and on the same subnet as the client.
                         * Save its address and netmask.
                         */
                        map = (mib2_ipAddrEntry_t *)(void *)item->valp;
                        while ((char *)map < item->valp + item->length) {
                                in_addr_t       addr, mask, net;
                                int             ifflags;

                                ifflags = map->ipAdEntInfo.ae_flags;
                                addr = map->ipAdEntAddr;
                                mask =  map->ipAdEntNetMask;
                                net = addr & mask;

                                if ((ifflags & IFF_LOOPBACK | IFF_UP) ==
                                    IFF_UP && addr != INADDR_ANY &&
                                    net == (client_addr.s_addr & mask)) {
                                        interface_addr.s_addr = addr;
                                        interface_mask.s_addr = mask;
                                        found = B_TRUE;
                                        break;
                                }
                                map++;
                        }
                }
        }

        /*
         * If this exercise found no interface on the same subnet as
         * the client, then we can't suggest any router address to
         * use.
         */
        if (interface_addr.s_addr == 0) {
                if (debug)
                        msgout("get_ip_route: no interface on same net "
                            "as client");
                (void) close(sd);
                free_itemlist(item_list);
                return (0);
        }

        /*
         * If we are a router, we return to client the address of our
         * interface on the same net as the client.
         */
        if (ip_forwarding == 1) {
                if (debug)
                        msgout("get_ip_route: returning local addr %s",
                                inet_ntoa(interface_addr));
                (void) close(sd);
                free_itemlist(item_list);
                return (interface_addr.s_addr);
        }

        if (debug) {
                msgout("interface_addr = %s.", inet_ntoa(interface_addr));
                msgout("interface_mask = %s", inet_ntoa(interface_mask));
        }


        /*
         * The routing table group.
         */
        for (item = item_list; item; item = item->next_item) {
                if ((item->group == MIB2_IP) && (item->mib_id == MIB2_IP_21)) {
                        if (debug)
                                msgout("%lu records for ipRouteEntryTable",
                                        item->length /
                                        sizeof (mib2_ipRouteEntry_t));

                        for (rp = (mib2_ipRouteEntry_t *)(void *)item->valp;
                                (char *)rp < item->valp + item->length;
                                rp++) {
                                if (debug >= 2)
                                        msgout("ire_type = %d, next_hop = 0x%x",
                                                rp->ipRouteInfo.re_ire_type,
                                                rp->ipRouteNextHop);

                                /*
                                 * We are only interested in real
                                 * gateway routes.
                                 */
                                if ((rp->ipRouteInfo.re_ire_type !=
                                    IRE_DEFAULT) &&
                                    (rp->ipRouteInfo.re_ire_type !=
                                    IRE_PREFIX) &&
                                    (rp->ipRouteInfo.re_ire_type !=
                                    IRE_HOST) &&
                                    (rp->ipRouteInfo.re_ire_type !=
                                    IRE_HOST_REDIRECT))
                                        continue;

                                /*
                                 * We are only interested in routes with
                                 * a next hop on the same subnet as
                                 * the client.
                                 */
                                if ((rp->ipRouteNextHop &
                                        interface_mask.s_addr) !=
                                    (interface_addr.s_addr &
                                        interface_mask.s_addr))
                                        continue;

                                /*
                                 * We have a valid route.  Give preference
                                 * to default routes.
                                 */
                                if ((rp->ipRouteDest == 0) ||
                                    (best_router.s_addr == 0))
                                        best_router.s_addr =
                                                rp->ipRouteNextHop;
                        }
                }
        }

        if (debug && (best_router.s_addr == 0))
                msgout("get_ip_route: no route found for client");

        (void) close(sd);
        free_itemlist(item_list);
        return (best_router.s_addr);
}

/*
 * Return address of server interface closest to client.
 *
 * If the server has only a single IP address return it. Otherwise check
 * if the server has an interface on the same subnet as the client and
 * return the address of that interface.
 */

in_addr_t
find_best_server_int(char **addr_list, char *client_name)
{
        in_addr_t               server_addr = 0;
        struct hostent          h, *hp;
        char                    hbuf[NSS_BUFLEN_HOSTS];
        int                     err;
        struct in_addr          client_addr;
        mib_item_t              *item_list;
        mib_item_t              *item;
        int                     sd;
        mib2_ipAddrEntry_t      *map;
        in_addr_t               client_net = 0, client_mask = 0;
        boolean_t               found_client_int;

        (void) memcpy(&server_addr, addr_list[0], sizeof (in_addr_t));
        if (addr_list[1] == NULL)
                return (server_addr);

        hp = gethostbyname_r(client_name, &h, hbuf, sizeof (hbuf), &err);
        if (hp == NULL)
                return (server_addr);
        (void) memcpy(&client_addr, hp->h_addr_list[0], sizeof (client_addr));

        /* open a stream to IP */
        sd = open("/dev/ip", O_RDWR);
        if (sd == -1) {
                perror("ip open");
                (void) close(sd);
                msgout("can't open mib stream");
                return (server_addr);
        }

        /* send down a request and suck up all the mib info from IP */
        if ((item_list = mibget(sd)) == nilp(mib_item_t)) {
                msgout("mibget() failed");
                (void) close(sd);
                return (server_addr);
        }
        (void) close(sd);

        /*
         * Search through the list for our interface which is on the same
         * subnet as the client and get the netmask.
         */
        for (item = item_list, found_client_int = B_FALSE;
            item != NULL && !found_client_int; item = item->next_item) {
                if ((item->group == MIB2_IP) && (item->mib_id == MIB2_IP_20)) {
                        /*
                         * Try to find out which interface is up, configured,
                         * not loopback, and on the same subnet as the client.
                         * Save its address and netmask.
                         */
                        map = (mib2_ipAddrEntry_t *)(void *)item->valp;
                        while ((char *)map < item->valp + item->length) {
                                in_addr_t       addr, mask, net;
                                int             ifflags;

                                ifflags = map->ipAdEntInfo.ae_flags;
                                addr = map->ipAdEntAddr;
                                mask =  map->ipAdEntNetMask;
                                net = addr & mask;

                                if ((ifflags & IFF_LOOPBACK|IFF_UP) == IFF_UP &&
                                    addr != INADDR_ANY &&
                                    (client_addr.s_addr & mask) == net) {
                                        client_net = net;
                                        client_mask = mask;
                                        found_client_int = B_TRUE;
                                        break;
                                }
                                map++;
                        }
                }
        }

        /*
         * If we found the interface check which is the best IP address.
         */
        if (found_client_int) {
                while (*addr_list != NULL) {
                        in_addr_t       addr;

                        (void) memcpy(&addr, *addr_list, sizeof (in_addr_t));
                        if ((addr & client_mask) == client_net) {
                                server_addr = addr;
                                break;
                        }
                        addr_list++;
                }
        }

        if (debug && server_addr == 0)
                msgout("No usable interface for returning reply");

        free_itemlist(item_list);
        return (server_addr);
}