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#include <u.h>
#include <libc.h>
#include <ip.h>
#include <bio.h>
#include <ndb.h>
#include "dat.h"

/*
 *      ala rfc2131
 */

enum {
        Maxloglen = 1024,
};

typedef struct Req Req;
struct Req
{
        int     fd;                     /* for reply */
        Bootp   *bp;
        Udphdr  *up;
        uchar   *e;                     /* end of received message */
        uchar   *p;                     /* options pointer */
        uchar   *max;                   /* max end of reply */

        /* expanded to v6 */
        uchar   ciaddr[IPaddrlen];
        uchar   giaddr[IPaddrlen];

        /* parsed options */
        int     p9request;              /* flag: this is a bootp with plan9 options */
        int     genrequest;             /* flag: this is a bootp with generic options */
        int     broadcast;              /* flag: request was broadcast */
        int     dhcptype;               /* dhcp message type */
        int     leasetime;              /* dhcp lease */
        uchar   ip[IPaddrlen];          /* requested address */
        uchar   server[IPaddrlen];      /* server address */
        char    msg[ERRMAX];            /* error message */
        char    vci[32];                /* vendor class id */
        char    *id;                    /* client id */
        uchar   requested[32];          /* requested params */
        uchar   vendorclass[32];
        char    cputype[32-3];

        Info    gii;                    /* about target network */
        Info    ii;                     /* about target system */
        int     staticbinding;

        uchar buf[2*1024];              /* message buffer */
};

#define TFTP "/lib/tftpd"

char    *blog = "ipboot";
char    mysysname[64];
Ipifc   *ipifcs;
int     debug;
int     nobootp;
long    now;
int     slowstat, slowdyn;
char    net[256];

int     pptponly;       /* only answer request that came from the pptp server */
int     mute, mutestat;
int     minlease = MinLease;
int     staticlease = StaticLease;

uvlong  start;

static int v6opts;

/* option magic */
char plan9opt[4] = { 'p', '9', ' ', ' ' };
char genericopt[4] = { 0x63, 0x82, 0x53, 0x63 };

/* well known addresses */
uchar zeros[Maxhwlen];

/* option debug buffer */
char optbuf[1024];
char *op;
char *oe = optbuf + sizeof(optbuf);

char *optname[256] =
{
[OBend]                 "end",
[OBpad]                 "pad",
[OBmask]                "mask",
[OBtimeoff]             "timeoff",
[OBrouter]              "router",
[OBtimeserver]          "time",
[OBnameserver]          "name",
[OBdnserver]            "dns",
[OBlogserver]           "log",
[OBcookieserver]        "cookie",
[OBlprserver]           "lpr",
[OBimpressserver]       "impress",
[OBrlserver]            "rl",
[OBhostname]            "host",
[OBbflen]               "bflen",
[OBdumpfile]            "dumpfile",
[OBdomainname]          "dom",
[OBswapserver]          "swap",
[OBrootpath]            "rootpath",
[OBextpath]             "extpath",
[OBipforward]           "ipforward",
[OBnonlocal]            "nonlocal",
[OBpolicyfilter]        "policyfilter",
[OBmaxdatagram]         "maxdatagram",
[OBttl]                 "ttl",
[OBpathtimeout]         "pathtimeout",
[OBpathplateau]         "pathplateau",
[OBmtu]                 "mtu",
[OBsubnetslocal]        "subnetslocal",
[OBbaddr]               "baddr",
[OBdiscovermask]        "discovermask",
[OBsupplymask]          "supplymask",
[OBdiscoverrouter]      "discoverrouter",
[OBrsserver]            "rsserver",
[OBstaticroutes]        "staticroutes",
[OBtrailerencap]        "trailerencap",
[OBarptimeout]          "arptimeout",
[OBetherencap]          "etherencap",
[OBtcpttl]              "tcpttl",
[OBtcpka]               "tcpka",
[OBtcpkag]              "tcpkag",
[OBnisdomain]           "nisdomain",
[OBniserver]            "niserver",
[OBntpserver]           "ntpserver",
[OBvendorinfo]          "vendorinfo",
[OBnetbiosns]           "NBns",
[OBnetbiosdds]          "NBdds",
[OBnetbiostype]         "NBtype",
[OBnetbiosscope]        "NBscope",
[OBxfontserver]         "xfont",
[OBxdispmanager]        "xdisp",
[OBnisplusdomain]       "NPdomain",
[OBnisplusserver]       "NP",
[OBhomeagent]           "homeagent",
[OBsmtpserver]          "smtp",
[OBpop3server]          "pop3",
[OBnntpserver]          "nntp",
[OBwwwserver]           "www",
[OBfingerserver]        "finger",
[OBircserver]           "ircserver",
[OBstserver]            "stserver",
[OBstdaserver]          "stdaserver",

/* dhcp options */
[ODipaddr]              "ip",
[ODlease]               "leas",
[ODoverload]            "overload",
[ODtype]                "typ",
[ODserverid]            "sid",
[ODparams]              "params",
[ODmessage]             "message",
[ODmaxmsg]              "maxmsg",
[ODrenewaltime]         "renewaltime",
[ODrebindingtime]       "rebindingtime",
[ODvendorclass]         "vendorclass",
[ODclientid]            "cid",
[ODtftpserver]          "tftpserver",
[ODbootfile]            "bf",
};

void    addropt(Req*, int, uchar*);
void    addrsopt(Req*, int, uchar**, int);
void    arpenter(uchar*, uchar*);
void    bootp(Req*);
void    byteopt(Req*, int, uchar);
void    dhcp(Req*);
void    fatal(int, char*, ...);
void    hexopt(Req*, int, char*);
void    logdhcp(Req*);
void    logdhcpout(Req *, char *);
void    longopt(Req*, int, long);
void    maskopt(Req*, int, uchar*);
void    miscoptions(Req*, uchar*);
int     openlisten(char *net);
void    p9addrsopt(Req *rp, int t, uchar **ip, int i);
void    parseoptions(Req*);
void    proto(Req*, int);
void    rcvdecline(Req*);
void    rcvdiscover(Req*);
void    rcvinform(Req*);
void    rcvrelease(Req*);
void    rcvrequest(Req*);
int     readlast(int, uchar*, int);
char*   readsysname(void);
void    remrequested(Req*, int);
void    sendack(Req*, uchar*, int, int);
void    sendnak(Req*, char*);
void    sendoffer(Req*, uchar*, int);
void    stringopt(Req*, int, char*);
void    termopt(Req*);
int     validip(uchar*);
void    vectoropt(Req*, int, uchar*, int);
void    warning(int, char*, ...);

void
timestamp(char *tag)
{
        uvlong t;

        t = nsec()/1000;
        syslog(0, blog, "%s %lludµs", tag, t - start);
}

void
usage(void)
{
        fprint(2, "usage: dhcp [-dmnprsSZ] [-f directory] [-M minlease] "
                "[-x netmtpt] [-Z staticlease] addr n [addr n] ...\n");
        exits("usage");
}

void
main(int argc, char **argv)
{
        int i, n, fd;
        uchar ip[IPaddrlen];
        Req r;

        setnetmtpt(net, sizeof net, nil);

        fmtinstall('E', eipfmt);
        fmtinstall('I', eipfmt);
        fmtinstall('V', eipfmt);
        fmtinstall('M', eipfmt);
        ARGBEGIN {
        case '6':
                v6opts = 1;
                break;
        case 'd':
                debug = 1;
                break;
        case 'f':
                ndbfile = EARGF(usage());
                break;
        case 'm':
                mute = 1;
                break;
        case 'M':
                minlease = atoi(EARGF(usage()));
                if(minlease <= 0)
                        minlease = MinLease;
                break;
        case 'n':
                nobootp = 1;
                break;
        case 'p':
                pptponly = 1;
                break;
        case 'r':
                mutestat = 1;
                break;
        case 's':
                slowstat = 1;
                break;
        case 'S':
                slowdyn = 1;
                break;
        case 'x':
                setnetmtpt(net, sizeof net, EARGF(usage()));
                break;
        case 'Z':
                staticlease = atoi(EARGF(usage()));
                if(staticlease <= 0)
                        staticlease = StaticLease;
                break;
        default:
                usage();
                break;
        } ARGEND;

        while(argc > 1){
                parseip(ip, argv[0]);
                if(!validip(ip))
                        usage();
                n = atoi(argv[1]);
                if(n <= 0)
                        usage();
                initbinding(ip, n);
                argc -= 2;
                argv += 2;
        }

        /* for debugging */
        for(i = 0; i < 256; i++)
                if(optname[i] == 0)
                        optname[i] = smprint("%d", i);

        /* what is my name? */
        strcpy(mysysname, readsysname());

        /* put process in background */
        if(!debug)
        switch(rfork(RFNOTEG|RFPROC|RFFDG)) {
        case -1:
                fatal(1, "fork");
        case 0:
                break;
        default:
                exits(0);
        }

        if (chdir(TFTP) < 0)
                warning(1, "can't change directory to %s", TFTP);
        fd = openlisten(net);

        for(;;){
                memset(&r, 0, sizeof(r));
                r.fd = fd;
                n = readlast(r.fd, r.buf, sizeof(r.buf));
                if(n < Udphdrsize)
                        fatal(1, "error reading requests");
                start = nsec()/1000;
                op = optbuf;
                *op = 0;
                proto(&r, n);
                if(r.id != nil)
                        free(r.id);
        }
}

void
proto(Req *rp, int n)
{
        uchar relip[IPaddrlen];
        char buf[64];

        now = time(0);

        rp->e = rp->buf + n;
        rp->bp = (Bootp*)rp->buf;
        rp->up = (Udphdr*)rp->buf;
        if (ipcmp(rp->up->laddr, IPv4bcast) == 0){
                ipmove(rp->up->laddr, rp->up->ifcaddr);
                rp->broadcast = 1;
        }
        rp->max = rp->buf + Udphdrsize + MINSUPPORTED - IPUDPHDRSIZE;
        rp->p = rp->bp->optdata;
        v4tov6(rp->giaddr, rp->bp->giaddr);
        v4tov6(rp->ciaddr, rp->bp->ciaddr);

        if(pptponly && rp->bp->htype != 0)
                return;

        ipifcs = readipifc(net, ipifcs, -1);
        if(validip(rp->giaddr))
                ipmove(relip, rp->giaddr);
        else if(validip(rp->up->raddr))
                ipmove(relip, rp->up->raddr);
        else
                ipmove(relip, rp->up->laddr);
        if(rp->e < (uchar*)rp->bp->sname){
                warning(0, "packet too short");
                return;
        }
        if(rp->bp->op != Bootrequest){
                warning(0, "not bootrequest");
                return;
        }

        if(rp->e >= rp->bp->optdata){
                if(memcmp(rp->bp->optmagic, plan9opt, sizeof(rp->bp->optmagic)) == 0)
                        rp->p9request = 1;
                if(memcmp(rp->bp->optmagic, genericopt, sizeof(rp->bp->optmagic)) == 0) {
                        rp->genrequest = 1;
                        parseoptions(rp);
                }
        }
        rp->p = rp->bp->optdata;

        /*  If no id is specified, make one from the hardware address
         *  of the target.  We assume all zeros is not a hardware address
         *  which could be a mistake.
         */
        if(rp->id == nil){
                if(rp->bp->hlen > Maxhwlen){
                        warning(0, "hlen %d", rp->bp->hlen);
                        return;
                }
                if(memcmp(zeros, rp->bp->chaddr, rp->bp->hlen) == 0){
                        warning(0, "no chaddr");
                        return;
                }
                sprint(buf, "hwa%2.2ux_", rp->bp->htype);
                rp->id = tohex(buf, rp->bp->chaddr, rp->bp->hlen);
        }

        /* info about gateway */
        if(lookupip(relip, &rp->gii, 1) < 0){
                warning(0, "lookupip failed");
                return;
        }

        /* info about target system */
        if(lookup(rp->bp, &rp->ii, &rp->gii) == 0)
                if(rp->ii.indb && rp->ii.dhcpgroup[0] == 0)
                        rp->staticbinding = 1;

        if(rp->dhcptype)
                dhcp(rp);
        else
                bootp(rp);
        timestamp("done");
}

/*
 * since we are single-threaded, this causes us to effectively
 * stop listening while we sleep.
 */
static void
slowdelay(Req *rp)
{
        if(slowstat && rp->staticbinding || slowdyn && !rp->staticbinding)
                sleep(1000);
}

void
dhcp(Req *rp)
{
        logdhcp(rp);

        switch(rp->dhcptype){
        case Discover:
                slowdelay(rp);
                rcvdiscover(rp);
                break;
        case Request:
                rcvrequest(rp);
                break;
        case Decline:
                rcvdecline(rp);
                break;
        case Release:
                rcvrelease(rp);
                break;
        case Inform:
                rcvinform(rp);
                break;
        }
}

void
rcvdiscover(Req *rp)
{
        Binding *b, *nb;

        if(rp->staticbinding){
                sendoffer(rp, rp->ii.ipaddr, (staticlease > minlease? staticlease: minlease));
                return;
        }

        /*
         *  first look for an outstanding offer
         */
        b = idtooffer(rp->id, &rp->gii);

        /*
         * rfc2131 says:
         *   If an address is available, the new address
         *   SHOULD be chosen as follows:
         *
         *      o The client's current address as recorded in the client's current
         *        binding, ELSE
         *
         *      o The client's previous address as recorded in the client's (now
         *        expired or released) binding, if that address is in the server's
         *        pool of available addresses and not already allocated, ELSE
         *
         *      o The address requested in the 'Requested IP Address' option, if that
         *        address is valid and not already allocated, ELSE
         *
         *      o A new address allocated from the server's pool of available
         *        addresses; the address is selected based on the subnet from which
         *        the message was received (if 'giaddr' is 0) or on the address of
         *        the relay agent that forwarded the message ('giaddr' when not 0).
         */
        if(b == nil){
                b = idtobinding(rp->id, &rp->gii, 1);
                if(b && b->boundto && strcmp(b->boundto, rp->id) != 0)
                if(validip(rp->ip) && samenet(rp->ip, &rp->gii)){
                        nb = iptobinding(rp->ip, 0);
                        if(nb && nb->lease < now)
                                b = nb;
                }
        }
        if(b == nil){
                warning(0, "!Discover(%s via %I): no binding %I",
                        rp->id, rp->gii.ipaddr, rp->ip);
                return;
        }
        mkoffer(b, rp->id, rp->leasetime);
        sendoffer(rp, b->ip, b->offer);
}

void
rcvrequest(Req *rp)
{
        Binding *b;

        if(validip(rp->server)){
                /* this is a reply to an offer - SELECTING */

                /* check for hard assignment */
                if(rp->staticbinding){
                        if(forme(rp->server))
                                sendack(rp, rp->ii.ipaddr,
                                        (staticlease > minlease? staticlease:
                                        minlease), 1);
                        else
                                warning(0, "!Request(%s via %I): for server %I not me",
                                        rp->id, rp->gii.ipaddr, rp->server);
                        return;
                }

                b = idtooffer(rp->id, &rp->gii);

                /* if we don't have an offer, nak */
                if(b == nil){
                        warning(0, "!Request(%s via %I): no offer",
                                rp->id, rp->gii.ipaddr);
                        if(forme(rp->server))
                                sendnak(rp, "no offer for you");
                        return;
                }

                /* if not for me, retract offer */
                if(!forme(rp->server)){
                        b->expoffer = 0;
                        warning(0, "!Request(%s via %I): for server %I not me",
                                rp->id, rp->gii.ipaddr, rp->server);
                        return;
                }

                /*
                 *  if the client is confused about what we offered, nak.
                 *  client really shouldn't be specifying this when selecting
                 */
                if(validip(rp->ip) && ipcmp(rp->ip, b->ip) != 0){
                        warning(0, "!Request(%s via %I): requests %I, not %I",
                                rp->id, rp->gii.ipaddr, rp->ip, b->ip);
                        sendnak(rp, "bad ip address option");
                        return;
                }
                if(commitbinding(b) < 0){
                        warning(0, "!Request(%s via %I): can't commit %I",
                                rp->id, rp->gii.ipaddr, b->ip);
                        sendnak(rp, "can't commit binding");
                        return;
                }
                sendack(rp, b->ip, b->offer, 1);
        } else if(validip(rp->ip)){
                /*
                 *  checking address/net - INIT-REBOOT
                 *
                 *  This is a rebooting client that remembers its old
                 *  address.
                 */
                /* check for hard assignment */
                if(rp->staticbinding){
                        if(memcmp(rp->ip, rp->ii.ipaddr, IPaddrlen) != 0){
                                warning(0, "!Request(%s via %I): %I not valid for %E",
                                        rp->id, rp->gii.ipaddr, rp->ip, rp->bp->chaddr);
                                sendnak(rp, "not valid");
                        }
                        sendack(rp, rp->ii.ipaddr, (staticlease > minlease?
                                staticlease: minlease), 1);
                        return;
                }

                /* make sure the network makes sense */
                if(!samenet(rp->ip, &rp->gii)){
                        warning(0, "!Request(%s via %I): bad forward of %I",
                                rp->id, rp->gii.ipaddr, rp->ip);
                        sendnak(rp, "wrong network");
                        return;
                }
                b = iptobinding(rp->ip, 0);
                if(b == nil){
                        warning(0, "!Request(%s via %I): no binding for %I",
                                rp->id, rp->gii.ipaddr, rp->ip);
                        return;
                }
                if(memcmp(rp->ip, b->ip, IPaddrlen) != 0 || now > b->lease){
                        warning(0, "!Request(%s via %I): %I not valid",
                                rp->id, rp->gii.ipaddr, rp->ip);
                        sendnak(rp, "not valid");
                        return;
                }
                b->offer = b->lease - now;
                sendack(rp, b->ip, b->offer, 1);
        } else if(validip(rp->ciaddr)){
                /*
                 *  checking address - RENEWING or REBINDING
                 *
                 *  these states are indistinguishable in our action.  The only
                 *  difference is how close to lease expiration the client is.
                 *  If it is really close, it broadcasts the request hoping that
                 *  some server will answer.
                 */

                /* check for hard assignment */
                if(rp->staticbinding){
                        if(ipcmp(rp->ciaddr, rp->ii.ipaddr) != 0){
                                warning(0, "!Request(%s via %I): %I not valid",
                                        rp->id, rp->gii.ipaddr, rp->ciaddr);
                                sendnak(rp, "not valid");
                        }
                        sendack(rp, rp->ii.ipaddr, (staticlease > minlease?
                                staticlease: minlease), 1);
                        return;
                }

                /* make sure the network makes sense */
                if(!samenet(rp->ciaddr, &rp->gii)){
                        warning(0, "!Request(%s via %I): bad forward of %I",
                                rp->id, rp->gii.ipaddr, rp->ip);
                        sendnak(rp, "wrong network");
                        return;
                }
                b = iptobinding(rp->ciaddr, 0);
                if(b == nil){
                        warning(0, "!Request(%s via %I): no binding for %I",
                                rp->id, rp->gii.ipaddr, rp->ciaddr);
                        return;
                }
                if(ipcmp(rp->ciaddr, b->ip) != 0){
                        warning(0, "!Request(%I via %s): %I not valid",
                                rp->id, rp->gii.ipaddr, rp->ciaddr);
                        sendnak(rp, "invalid ip address");
                        return;
                }
                mkoffer(b, rp->id, rp->leasetime);
                if(commitbinding(b) < 0){
                        warning(0, "!Request(%s via %I): can't commit %I",
                                rp->id, rp->gii.ipaddr, b->ip);
                        sendnak(rp, "can't commit binding");
                        return;
                }
                sendack(rp, b->ip, b->offer, 1);
        }
}

void
rcvdecline(Req *rp)
{
        Binding *b;
        char buf[64];

        if(rp->staticbinding)
                return;

        b = idtooffer(rp->id, &rp->gii);
        if(b == nil){
                warning(0, "!Decline(%s via %I): no binding",
                        rp->id, rp->gii.ipaddr);
                return;
        }

        /* mark ip address as in use */
        snprint(buf, sizeof(buf), "declined by %s", rp->id);
        mkoffer(b, buf, 0x7fffffff);
        commitbinding(b);
}

void
rcvrelease(Req *rp)
{
        Binding *b;

        if(rp->staticbinding)
                return;

        b = idtobinding(rp->id, &rp->gii, 0);
        if(b == nil){
                warning(0, "!Release(%s via %I): no binding",
                        rp->id, rp->gii.ipaddr);
                return;
        }
        if(strcmp(rp->id, b->boundto) != 0){
                warning(0, "!Release(%s via %I): invalid release of %I",
                        rp->id, rp->gii.ipaddr, rp->ip);
                return;
        }
        warning(0, "Release(%s via %I): releasing %I", b->boundto, rp->gii.ipaddr, b->ip);
        if(releasebinding(b, rp->id) < 0)
                warning(0, "release: couldn't release");
}

void
rcvinform(Req *rp)
{
        Binding *b;

        if(rp->staticbinding){
                sendack(rp, rp->ii.ipaddr, 0, 0);
                return;
        }

        b = iptobinding(rp->ciaddr, 0);
        if(b == nil){
                warning(0, "!Inform(%s via %I): no binding for %I",
                        rp->id, rp->gii.ipaddr, rp->ip);
                return;
        }
        sendack(rp, b->ip, 0, 0);
}

int
setsiaddr(uchar *siaddr, uchar *saddr, uchar *laddr)
{
        if(ipcmp(saddr, IPnoaddr) != 0){
                v6tov4(siaddr, saddr);
                return 0;
        } else {
                v6tov4(siaddr, laddr);
                return 1;
        }
}

int
ismuted(Req *rp)
{
        return mute || (mutestat && rp->staticbinding);
}

void
sendoffer(Req *rp, uchar *ip, int offer)
{
        int n;
        ushort flags;
        Bootp *bp;
        Udphdr *up;

        bp = rp->bp;
        up = rp->up;

        /*
         *  set destination
         */
        flags = nhgets(bp->flags);
        if(validip(rp->giaddr)){
                ipmove(up->raddr, rp->giaddr);
                hnputs(up->rport, 67);
        } else if(flags & Fbroadcast){
                ipmove(up->raddr, IPv4bcast);
                hnputs(up->rport, 68);
        } else {
                ipmove(up->raddr, ip);
                if(bp->htype == 1)
                        arpenter(up->raddr, bp->chaddr);
                hnputs(up->rport, 68);
        }

        /*
         *  fill in standard bootp part
         */
        bp->op = Bootreply;
        bp->hops = 0;
        hnputs(bp->secs, 0);
        memset(bp->ciaddr, 0, sizeof(bp->ciaddr));
        v6tov4(bp->giaddr, rp->giaddr);
        v6tov4(bp->yiaddr, ip);
        setsiaddr(bp->siaddr, rp->ii.tftp, up->laddr);
        strncpy(bp->sname, mysysname, sizeof(bp->sname));
        strncpy(bp->file, rp->ii.bootf, sizeof(bp->file));

        /*
         *  set options
         */
        byteopt(rp, ODtype, Offer);
        longopt(rp, ODlease, offer);
        addropt(rp, ODserverid, up->laddr);
        miscoptions(rp, ip);
        termopt(rp);

        logdhcpout(rp, "Offer");

        /*
         *  send
         */
        n = rp->p - rp->buf;
        if(!ismuted(rp) && write(rp->fd, rp->buf, n) != n)
                warning(0, "offer: write failed: %r");
}

void
sendack(Req *rp, uchar *ip, int offer, int sendlease)
{
        int n;
        ushort flags;
        Bootp *bp;
        Udphdr *up;

        bp = rp->bp;
        up = rp->up;

        /*
         *  set destination
         */
        flags = nhgets(bp->flags);
        if(validip(rp->giaddr)){
                ipmove(up->raddr, rp->giaddr);
                hnputs(up->rport, 67);
        } else if(flags & Fbroadcast){
                ipmove(up->raddr, IPv4bcast);
                hnputs(up->rport, 68);
        } else {
                ipmove(up->raddr, ip);
                if(bp->htype == 1)
                        arpenter(up->raddr, bp->chaddr);
                hnputs(up->rport, 68);
        }

        /*
         *  fill in standard bootp part
         */
        bp->op = Bootreply;
        bp->hops = 0;
        hnputs(bp->secs, 0);
        v6tov4(bp->giaddr, rp->giaddr);
        v6tov4(bp->yiaddr, ip);
        setsiaddr(bp->siaddr, rp->ii.tftp, up->laddr);
        strncpy(bp->sname, mysysname, sizeof(bp->sname));
        strncpy(bp->file, rp->ii.bootf, sizeof(bp->file));

        /*
         *  set options
         */
        byteopt(rp, ODtype, Ack);
        if(sendlease){
                longopt(rp, ODlease, offer);
        }
        addropt(rp, ODserverid, up->laddr);
        miscoptions(rp, ip);
        termopt(rp);

        logdhcpout(rp, "Ack");

        /*
         *  send
         */
        n = rp->p - rp->buf;
        if(!ismuted(rp) && write(rp->fd, rp->buf, n) != n)
                warning(0, "ack: write failed: %r");
}

void
sendnak(Req *rp, char *msg)
{
        int n;
        Bootp *bp;
        Udphdr *up;

        bp = rp->bp;
        up = rp->up;

        /*
         *  set destination (always broadcast)
         */
        if(validip(rp->giaddr)){
                ipmove(up->raddr, rp->giaddr);
                hnputs(up->rport, 67);
        } else {
                ipmove(up->raddr, IPv4bcast);
                hnputs(up->rport, 68);
        }

        /*
         *  fill in standard bootp part
         */
        bp->op = Bootreply;
        bp->hops = 0;
        hnputs(bp->secs, 0);
        v6tov4(bp->giaddr, rp->giaddr);
        memset(bp->ciaddr, 0, sizeof(bp->ciaddr));
        memset(bp->yiaddr, 0, sizeof(bp->yiaddr));
        memset(bp->siaddr, 0, sizeof(bp->siaddr));

        /*
         *  set options
         */
        byteopt(rp, ODtype, Nak);
        addropt(rp, ODserverid, up->laddr);
        if(msg)
                stringopt(rp, ODmessage, msg);
        if(strncmp(rp->id, "id", 2) == 0)
                hexopt(rp, ODclientid, rp->id+2);
        termopt(rp);

        logdhcpout(rp, "Nak");

        /*
         *  send nak
         */
        n = rp->p - rp->buf;
        if(!ismuted(rp) && write(rp->fd, rp->buf, n) != n)
                warning(0, "nak: write failed: %r");
}

void
bootp(Req *rp)
{
        int n;
        Bootp *bp;
        Udphdr *up;
        ushort flags;
        Iplifc *lifc;
        Info *iip;

        warning(0, "bootp %s %I->%I from %s via %I, file %s %s",
                rp->genrequest? "generic": (rp->p9request? "p9": ""),
                rp->up->raddr, rp->up->laddr,
                rp->id, rp->gii.ipaddr,
                rp->bp->file, rp->broadcast? "broadcast": "unicast");

        if(nobootp)
                return;

        bp = rp->bp;
        up = rp->up;
        iip = &rp->ii;

        if(rp->staticbinding == 0){
                warning(0, "bootp from unknown %s via %I", rp->id, rp->gii.ipaddr);
                return;
        }

        /* ignore if not for us */
        if(*bp->sname){
                if(strcmp(bp->sname, mysysname) != 0){
                        bp->sname[20] = 0;
                        warning(0, "bootp for server %s", bp->sname);
                        return;
                }
        } else
                slowdelay(rp);

        /* ignore if we don't know what file to load */
        if(*bp->file == 0){
                if(rp->genrequest && *iip->bootf2) /* if not plan 9 & have alternate file... */
                        strncpy(bp->file, iip->bootf2, sizeof(bp->file));
                else if(*iip->bootf)
                        strncpy(bp->file, iip->bootf, sizeof(bp->file));
                else if(*bp->sname) /* if we were asked, respond no matter what */
                        bp->file[0] = '\0';
                else {
                        warning(0, "no bootfile for %I", iip->ipaddr);
                        return;
                }
        }

        /* ignore if the file is unreadable */
        if((!rp->genrequest) && bp->file[0] && access(bp->file, 4) < 0){
                warning(0, "inaccessible bootfile1 %s", bp->file);
                return;
        }

        bp->op = Bootreply;
        v6tov4(bp->yiaddr, iip->ipaddr);
        if(rp->p9request){
                warning(0, "p9bootp: %I", iip->ipaddr);
                memmove(bp->optmagic, plan9opt, 4);
                if(iip->gwip == 0)
                        v4tov6(iip->gwip, bp->giaddr);
                rp->p += sprint((char*)rp->p, "%V %I %I %I", iip->ipmask+IPv4off, iip->fsip,
                                iip->auip, iip->gwip);
                sprint(optbuf, "%s", (char*)(bp->optmagic));
        } else if(rp->genrequest){
                warning(0, "genericbootp: %I", iip->ipaddr);
                memmove(bp->optmagic, genericopt, 4);
                miscoptions(rp, iip->ipaddr);
                termopt(rp);
        } else if(iip->vendor[0] != 0) {
                warning(0, "bootp vendor field: %s", iip->vendor);
                memset(rp->p, 0, 128-4);
                rp->p += sprint((char*)bp->optmagic, "%s", iip->vendor);
        } else {
                memset(rp->p, 0, 128-4);
                rp->p += 128-4;
        }

        /*
         *  set destination
         */
        flags = nhgets(bp->flags);
        if(validip(rp->giaddr)){
                ipmove(up->raddr, rp->giaddr);
                hnputs(up->rport, 67);
        } else if(flags & Fbroadcast){
                ipmove(up->raddr, IPv4bcast);
                hnputs(up->rport, 68);
        } else {
                v4tov6(up->raddr, bp->yiaddr);
                if(bp->htype == 1)
                        arpenter(up->raddr, bp->chaddr);
                hnputs(up->rport, 68);
        }

        /*
         *  select best local address if destination is directly connected
         */
        lifc = findlifc(up->raddr);
        if(lifc)
                ipmove(up->laddr, lifc->ip);

        /*
         *  our identity
         */
        strncpy(bp->sname, mysysname, sizeof(bp->sname));

        /*
         *  set tftp server
         */
        setsiaddr(bp->siaddr, iip->tftp, up->laddr);
        if(rp->genrequest && *iip->bootf2)
                setsiaddr(bp->siaddr, iip->tftp2, up->laddr);

        /*
         * RFC 1048 says that we must pad vendor field with
         * zeros until we have a 64 byte field.
         */
        n = rp->p - rp->bp->optdata;
        if(n < 64-4) {
                memset(rp->p, 0, (64-4)-n);
                rp->p += (64-4)-n;
        }

        /*
         *  send
         */
        n = rp->p - rp->buf;
        if(!ismuted(rp) && write(rp->fd, rp->buf, n) != n)
                warning(0, "bootp: write failed: %r");

        warning(0, "bootp via %I: file %s xid(%ux)flag(%ux)ci(%V)gi(%V)yi(%V)si(%V) %s",
                        up->raddr, bp->file, nhgetl(bp->xid), nhgets(bp->flags),
                        bp->ciaddr, bp->giaddr, bp->yiaddr, bp->siaddr,
                        optbuf);
}

void
parseoptions(Req *rp)
{
        int n, c, code;
        uchar *o, *p;

        p = rp->p;

        while(p < rp->e){
                code = *p++;
                if(code == 255)
                        break;
                if(code == 0)
                        continue;

                /* ignore anything that's too long */
                n = *p++;
                o = p;
                p += n;
                if(p > rp->e)
                        return;

                switch(code){
                case ODipaddr:  /* requested ip address */
                        if(n == IPv4addrlen)
                                v4tov6(rp->ip, o);
                        break;
                case ODlease:   /* requested lease time */
                        rp->leasetime = nhgetl(o);
                        if(rp->leasetime > MaxLease || rp->leasetime < 0)
                                rp->leasetime = MaxLease;
                        break;
                case ODtype:
                        c = *o;
                        if(c < 10 && c > 0)
                                rp->dhcptype = c;
                        break;
                case ODserverid:
                        if(n == IPv4addrlen)
                                v4tov6(rp->server, o);
                        break;
                case ODmessage:
                        if(n > sizeof rp->msg-1)
                                n = sizeof rp->msg-1;
                        memmove(rp->msg, o, n);
                        rp->msg[n] = 0;
                        break;
                case ODmaxmsg:
                        c = nhgets(o);
                        c -= 28;
                        c += Udphdrsize;
                        if(c > 0)
                                rp->max = rp->buf + c;
                        break;
                case ODclientid:
                        if(n <= 1)
                                break;
                        rp->id = toid( o, n);
                        break;
                case ODparams:
                        if(n > sizeof(rp->requested))
                                n = sizeof(rp->requested);
                        memmove(rp->requested, o, n);
                        break;
                case ODvendorclass:
                        if(n >= sizeof(rp->vendorclass))
                                n = sizeof(rp->vendorclass)-1;
                        memmove(rp->vendorclass, o, n);
                        rp->vendorclass[n] = 0;
                        if(strncmp((char*)rp->vendorclass, "p9-", 3) == 0)
                                strcpy(rp->cputype, (char*)rp->vendorclass+3);
                        break;
                case OBend:
                        return;
                }
        }
}

void
remrequested(Req *rp, int opt)
{
        uchar *p;

        p = memchr(rp->requested, opt, sizeof(rp->requested));
        if(p != nil)
                *p = OBpad;
}

void
miscoptions(Req *rp, uchar *ip)
{
        int i, j, na;
        uchar x[2*IPaddrlen], vopts[Maxoptlen];
        uchar *op, *omax;
        uchar *addrs[2];
        char *p;
        char *attr[100], **a;
        Ndbtuple *t;

        addrs[0] = x;
        addrs[1] = x+IPaddrlen;

        /* always supply these */
        maskopt(rp, OBmask, rp->gii.ipmask);
        if(validip(rp->gii.gwip)){
                remrequested(rp, OBrouter);
                addropt(rp, OBrouter, rp->gii.gwip);
        } else if(validip(rp->giaddr)){
                remrequested(rp, OBrouter);
                addropt(rp, OBrouter, rp->giaddr);
        }

        /*
         * OBhostname for the HP4000M switches
         * (this causes NT to log infinite errors - tough shit)
         */
        if(*rp->ii.domain){
                remrequested(rp, OBhostname);
                stringopt(rp, OBhostname, rp->ii.domain);
        }
        if(*rp->ii.rootpath)
                stringopt(rp, OBrootpath, rp->ii.rootpath);

        /* figure out what we need to lookup */
        na = 0;
        a = attr;
        if(*rp->ii.domain == 0)
                a[na++] = "dom";
        for(i = 0; i < sizeof(rp->requested); i++)
                switch(rp->requested[i]){
                case OBrouter:
                        a[na++] = "@ipgw";
                        break;
                case OBdnserver:
                        a[na++] = "@dns";
                        break;
                case OBnetbiosns:
                        a[na++] = "@wins";
                        break;
                case OBsmtpserver:
                        a[na++] = "@smtp";
                        break;
                case OBpop3server:
                        a[na++] = "@pop3";
                        break;
                case OBwwwserver:
                        a[na++] = "@www";
                        break;
                case OBntpserver:
                        a[na++] = "@ntp";
                        break;
                case OBtimeserver:
                        a[na++] = "@time";
                        break;
                }
        if(strncmp((char*)rp->vendorclass, "plan9_", 6) == 0
        || strncmp((char*)rp->vendorclass, "p9-", 3) == 0){
                a[na++] = "@fs";
                a[na++] = "@auth";
        }
        t = lookupinfo(ip, a, na);

        /* lookup anything we might be missing */
        if(*rp->ii.domain == 0)
                lookupname(rp->ii.domain, t);

        /* add any requested ones that we know about */
        for(i = 0; i < sizeof(rp->requested); i++)
                switch(rp->requested[i]){
                case OBrouter:
                        j = lookupserver("ipgw", addrs, t);
                        addrsopt(rp, OBrouter, addrs, j);
                        break;
                case OBdnserver:
                        j = lookupserver("dns", addrs, t);
                        addrsopt(rp, OBdnserver, addrs, j);
                        break;
                case OBhostname:
                        if(*rp->ii.domain)
                                stringopt(rp, OBhostname, rp->ii.domain);
                        break;
                case OBdomainname:
                        p = strchr(rp->ii.domain, '.');
                        if(p)
                                stringopt(rp, OBdomainname, p+1);
                        break;
                case OBnetbiosns:
                        j = lookupserver("wins", addrs, t);
                        addrsopt(rp, OBnetbiosns, addrs, j);
                        break;
                case OBnetbiostype:
                        /* p-node: peer to peer WINS queries */
                        byteopt(rp, OBnetbiostype, 0x2);
                        break;
                case OBsmtpserver:
                        j = lookupserver("smtp", addrs, t);
                        addrsopt(rp, OBsmtpserver, addrs, j);
                        break;
                case OBpop3server:
                        j = lookupserver("pop3", addrs, t);
                        addrsopt(rp, OBpop3server, addrs, j);
                        break;
                case OBwwwserver:
                        j = lookupserver("www", addrs, t);
                        addrsopt(rp, OBwwwserver, addrs, j);
                        break;
                case OBntpserver:
                        j = lookupserver("ntp", addrs, t);
                        addrsopt(rp, OBntpserver, addrs, j);
                        break;
                case OBtimeserver:
                        j = lookupserver("time", addrs, t);
                        addrsopt(rp, OBtimeserver, addrs, j);
                        break;
                case OBttl:
                        byteopt(rp, OBttl, 255);
                        break;
                }

        /* add plan9 specific options */
        if(strncmp((char*)rp->vendorclass, "plan9_", 6) == 0
        || strncmp((char*)rp->vendorclass, "p9-", 3) == 0){
                /* point to temporary area */
                op = rp->p;
                omax = rp->max;
                /* stash encoded options in vopts */
                rp->p = vopts;
                rp->max = vopts + sizeof(vopts) - 1;

                /* emit old v4 addresses first to make sure that they fit */
                addrsopt(rp, OP9fsv4, addrs, lookupserver("fs", addrs, t));
                addrsopt(rp, OP9authv4, addrs, lookupserver("auth", addrs, t));

                p9addrsopt(rp, OP9fs, addrs, lookupserver("fs", addrs, t));
                p9addrsopt(rp, OP9auth, addrs, lookupserver("auth", addrs, t));
                p9addrsopt(rp, OP9ipaddr, addrs, lookupserver("ip", addrs, t));
                p9addrsopt(rp, OP9ipmask, addrs, lookupserver("ipmask", addrs, t));
                p9addrsopt(rp, OP9ipgw, addrs, lookupserver("ipgw", addrs, t));

                /* point back to packet, encapsulate vopts into packet */
                j = rp->p - vopts;
                rp->p = op;
                rp->max = omax;
                vectoropt(rp, OBvendorinfo, vopts, j);
        }

        ndbfree(t);
}

int
openlisten(char *net)
{
        int fd, cfd;
        char data[128], devdir[40];

        sprint(data, "%s/udp!*!bootp", net);
        cfd = announce(data, devdir);
        if(cfd < 0)
                fatal(1, "can't announce");
        if(fprint(cfd, "headers") < 0)
                fatal(1, "can't set header mode");

        sprint(data, "%s/data", devdir);
        fd = open(data, ORDWR);
        if(fd < 0)
                fatal(1, "open udp data");
        return fd;
}

void
fatal(int syserr, char *fmt, ...)
{
        char buf[Maxloglen];
        va_list arg;

        va_start(arg, fmt);
        vseprint(buf, buf+sizeof(buf), fmt, arg);
        va_end(arg);
        if(syserr)
                syslog(1, blog, "%s: %r", buf);
        else
                syslog(1, blog, "%s", buf);
        exits(buf);
}

void
warning(int syserr, char *fmt, ...)
{
        char buf[Maxloglen];
        va_list arg;

        va_start(arg, fmt);
        vseprint(buf, buf+sizeof(buf), fmt, arg);
        va_end(arg);
        if(syserr){
                syslog(0, blog, "%s: %r", buf);
                if(debug)
                        fprint(2, "%s: %r\n", buf);
        } else {
                syslog(0, blog, "%s", buf);
                if(debug)
                        fprint(2, "%s\n", buf);
        }
}

char*
readsysname(void)
{
        static char name[128];
        char *p;
        int n, fd;

        fd = open("/dev/sysname", OREAD);
        if(fd >= 0){
                n = read(fd, name, sizeof(name)-1);
                close(fd);
                if(n > 0){
                        name[n] = 0;
                        return name;
                }
        }
        p = getenv("sysname");
        if(p == nil || *p == 0)
                return "unknown";
        return p;
}

extern int
validip(uchar *ip)
{
        if(ipcmp(ip, IPnoaddr) == 0)
                return 0;
        if(ipcmp(ip, v4prefix) == 0)
                return 0;
        return 1;
}

void
longopt(Req *rp, int t, long v)
{
        if(rp->p + 6 > rp->max)
                return;
        *rp->p++ = t;
        *rp->p++ = 4;
        hnputl(rp->p, v);
        rp->p += 4;

        op = seprint(op, oe, "%s(%ld)", optname[t], v);
}

void
addropt(Req *rp, int t, uchar *ip)
{
        if(rp->p + 6 > rp->max)
                return;
        if (!isv4(ip)) {
                if (debug)
                        warning(0, "not a v4 %s server: %I", optname[t], ip);
                return;
        }
        *rp->p++ = t;
        *rp->p++ = 4;
        memmove(rp->p, ip+IPv4off, 4);
        rp->p += 4;

        op = seprint(op, oe, "%s(%I)", optname[t], ip);
}

void
maskopt(Req *rp, int t, uchar *ip)
{
        if(rp->p + 6 > rp->max)
                return;
        *rp->p++ = t;
        *rp->p++ = 4;
        memmove(rp->p, ip+IPv4off, 4);
        rp->p += 4;

        op = seprint(op, oe, "%s(%M)", optname[t], ip);
}

void
addrsopt(Req *rp, int t, uchar **ip, int i)
{
        int v4s, n;

        if(i <= 0)
                return;
        if(rp->p + 2 + 4*i > rp->max)
                return;
        v4s = 0;
        for(n = i; n-- > 0; )
                if (isv4(ip[n]))
                        v4s++;
        if (v4s <= 0) {
                if (debug)
                        warning(0, "no v4 %s servers", optname[t]);
                return;
        }
        *rp->p++ = t;
        *rp->p++ = 4*v4s;
        op = seprint(op, oe, " %s(", optname[t]);
        while(i-- > 0){
                if (!isv4(*ip)) {
                        op = seprint(op, oe, " skipping %I ", *ip);
                        continue;
                }
                v6tov4(rp->p, *ip);
                rp->p += 4;
                op = seprint(op, oe, "%I", *ip);
                ip++;
                if(i > 0)
                        op = seprint(op, oe, " ");
        }
        op = seprint(op, oe, ")");
}

void
p9addrsopt(Req *rp, int t, uchar **ip, int i)
{
        char *pkt, *payload;

        if(i <= 0 || !v6opts)
                return;
        pkt = (char *)rp->p;
        *pkt++ = t;                     /* option */
        pkt++;                          /* fill in payload length below */
        payload = pkt;
        *pkt++ = i;                     /* plan 9 address count */
        op = seprint(op, oe, " %s(", optname[t]);
        while(i-- > 0){
                pkt = seprint(pkt, (char *)rp->max, "%I", *ip);
                if ((uchar *)pkt+1 >= rp->max) {
                        op = seprint(op, oe, "<out of mem1>)");
                        return;
                }
                pkt++;                  /* leave NUL as terminator */
                op = seprint(op, oe, "%I", *ip);
                ip++;
                if(i > 0)
                        op = seprint(op, oe, " ");
        }
        if ((uchar *)pkt - rp->p > 0377) {
                op = seprint(op, oe, "<out of mem2>)");
                return;
        }
        op = seprint(op, oe, ")");
        rp->p[1] = pkt - payload;       /* payload length */
        rp->p = (uchar *)pkt;
}

void
byteopt(Req *rp, int t, uchar v)
{
        if(rp->p + 3 > rp->max)
                return;
        *rp->p++ = t;
        *rp->p++ = 1;
        *rp->p++ = v;

        op = seprint(op, oe, "%s(%d)", optname[t], v);
}

void
termopt(Req *rp)
{
        if(rp->p + 1 > rp->max)
                return;
        *rp->p++ = OBend;
}

void
stringopt(Req *rp, int t, char *str)
{
        int n;

        n = strlen(str);
        if(n > 255)
                n = 255;
        if(rp->p+n+2 > rp->max)
                return;
        *rp->p++ = t;
        *rp->p++ = n;
        memmove(rp->p, str, n);
        rp->p += n;

        op = seprint(op, oe, "%s(%s)", optname[t], str);
}

void
vectoropt(Req *rp, int t, uchar *v, int n)
{
        int i;

        if(n > 255) {
                n = 255;
                op = seprint(op, oe, "vectoropt len %d > 255 ", n);
        }
        if(rp->p+n+2 > rp->max)
                return;
        *rp->p++ = t;
        *rp->p++ = n;
        memmove(rp->p, v, n);
        rp->p += n;

        op = seprint(op, oe, "%s(", optname[t]);
        if(n > 0)
                op = seprint(op, oe, "%ud", v[0]);
        for(i = 1; i < n; i++)
                op = seprint(op, oe, " %ud", v[i]);
        op = seprint(op, oe, ")");
}

int
fromhex(int x)
{
        if(x >= '0' && x <= '9')
                return x - '0';
        return x - 'a';
}

void
hexopt(Req *rp, int t, char *str)
{
        int n;

        n = strlen(str);
        n /= 2;
        if(n > 255)
                n = 255;
        if(rp->p+n+2 > rp->max)
                return;
        *rp->p++ = t;
        *rp->p++ = n;
        while(n-- > 0){
                *rp->p++ = (fromhex(str[0])<<4)|fromhex(str[1]);
                str += 2;
        }

        op = seprint(op, oe, "%s(%s)", optname[t], str);
}

void
arpenter(uchar *ip, uchar *ether)
{
        int f;
        char buf[256];

        sprint(buf, "%s/arp", net);
        f = open(buf, OWRITE);
        if(f < 0){
                syslog(debug, blog, "open %s: %r", buf);
                return;
        }
        fprint(f, "add ether %I %E", ip, ether);
        close(f);
}

char *dhcpmsgname[] =
{
        [Discover]      "Discover",
        [Offer]         "Offer",
        [Request]       "Request",
        [Decline]       "Decline",
        [Ack]           "Ack",
        [Nak]           "Nak",
        [Release]       "Release",
        [Inform]        "Inform",
};

void
logdhcp(Req *rp)
{
        char buf[4096];
        char *p, *e;
        int i;

        p = buf;
        e = buf + sizeof(buf);
        if(rp->dhcptype > 0 && rp->dhcptype <= Inform)
                p = seprint(p, e, "%s(", dhcpmsgname[rp->dhcptype]);
        else
                p = seprint(p, e, "%d(", rp->dhcptype);
        p = seprint(p, e, "%I->%I) xid(%ux)flag(%ux)", rp->up->raddr, rp->up->laddr,
                nhgetl(rp->bp->xid), nhgets(rp->bp->flags));
        if(rp->bp->htype == 1)
                p = seprint(p, e, "ea(%E)", rp->bp->chaddr);
        if(validip(rp->ciaddr))
                p = seprint(p, e, "ci(%I)", rp->ciaddr);
        if(validip(rp->giaddr))
                p = seprint(p, e, "gi(%I)", rp->giaddr);
        if(validip(rp->ip))
                p = seprint(p, e, "ip(%I)", rp->ip);
        if(rp->id != nil)
                p = seprint(p, e, "id(%s)", rp->id);
        if(rp->leasetime)
                p = seprint(p, e, "leas(%d)", rp->leasetime);
        if(validip(rp->server))
                p = seprint(p, e, "sid(%I)", rp->server);
        p = seprint(p, e, "need(");
        for(i = 0; i < sizeof(rp->requested); i++)
                if(rp->requested[i] != 0)
                        p = seprint(p, e, "%s ", optname[rp->requested[i]]);
        p = seprint(p, e, ")");
        p = seprint(p, e, " %s", rp->broadcast? "broadcast": "unicast");
        USED(p);
        syslog(0, blog, "%s", buf);
}

void
logdhcpout(Req *rp, char *type)
{
        syslog(0, blog, "%s(%I-%I)id(%s)ci(%V)gi(%V)yi(%V)si(%V) %s",
                type, rp->up->laddr, rp->up->raddr, rp->id,
                rp->bp->ciaddr, rp->bp->giaddr, rp->bp->yiaddr, rp->bp->siaddr, optbuf);
}

/*
 *  if we get behind, it's useless to try answering since the sender
 *  will probably have retransmitted with a differnt sequence number.
 *  So dump all but the last message in the queue.
 */
void
ding(void*, char *msg)
{
        if(strstr(msg, "alarm"))
                noted(NCONT);
        else
                noted(NDFLT);
}

int
readlast(int fd, uchar *buf, int len)
{
        int lastn, n;

        notify(ding);

        lastn = 0;
        for(;;){
                alarm(20);
                n = read(fd, buf, len);
                alarm(0);
                if(n < 0){
                        if(lastn > 0)
                                return lastn;
                        break;
                }
                lastn = n;
        }
        return read(fd, buf, len);
}