lib/libstand/udp.c

/* Taken from $NetBSD: net.c,v 1.20 1997/12/26 22:41:30 scottr Exp $    */

/*
 * Copyright (c) 1992 Regents of the University of California.
 * All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * 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.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 * @(#) Header: net.c,v 1.9 93/08/06 19:32:15 leres Exp  (LBL)
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/socket.h>

#include <string.h>

#include <net/if.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <netinet/in_systm.h>

#include <netinet/in_pcb.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>

#include "stand.h"
#include "net.h"

/* Caller must leave room for ethernet, ip and udp headers in front!! */
ssize_t
sendudp(d, pkt, len)
    struct iodesc *d;
    void *pkt;
    size_t len;
{
    ssize_t cc;
    struct ip *ip;
    struct udphdr *uh;
    u_char *ea;

#ifdef NET_DEBUG
    if (debug) {
        printf("sendudp: d=%lx called.\n", (long)d);
        if (d) {
            printf("saddr: %s:%d",
                inet_ntoa(d->myip), ntohs(d->myport));
            printf(" daddr: %s:%d\n",
                inet_ntoa(d->destip), ntohs(d->destport));
        }
    }
#endif

    uh = (struct udphdr *)pkt - 1;
    ip = (struct ip *)uh - 1;
    len += sizeof(*ip) + sizeof(*uh);

    bzero(ip, sizeof(*ip) + sizeof(*uh));

    ip->ip_v = IPVERSION;           /* half-char */
    ip->ip_hl = sizeof(*ip) >> 2;       /* half-char */
    ip->ip_len = htons(len);
    ip->ip_p = IPPROTO_UDP;         /* char */
    ip->ip_ttl = IPDEFTTL;          /* char */
    ip->ip_src = d->myip;
    ip->ip_dst = d->destip;
    ip->ip_sum = in_cksum(ip, sizeof(*ip));  /* short, but special */

    uh->uh_sport = d->myport;
    uh->uh_dport = d->destport;
    uh->uh_ulen = htons(len - sizeof(*ip));

#ifndef UDP_NO_CKSUM
    {
        struct udpiphdr *ui;
        struct ip tip;

        /* Calculate checksum (must save and restore ip header) */
        tip = *ip;
        ui = (struct udpiphdr *)ip;
        bzero(&ui->ui_x1, sizeof(ui->ui_x1));
        ui->ui_len = uh->uh_ulen;
        uh->uh_sum = in_cksum(ui, len);
        *ip = tip;
    }
#endif

    if (ip->ip_dst.s_addr == INADDR_BROADCAST || ip->ip_src.s_addr == 0 ||
        netmask == 0 || SAMENET(ip->ip_src, ip->ip_dst, netmask))
        ea = arpwhohas(d, ip->ip_dst);
    else
        ea = arpwhohas(d, gateip);

    cc = sendether(d, ip, len, ea, ETHERTYPE_IP);
    if (cc == -1)
        return (-1);
    if (cc != len)
        panic("sendudp: bad write (%zd != %zd)", cc, len);
    return (cc - (sizeof(*ip) + sizeof(*uh)));
}

/*
 * Receive a UDP packet and validate it is for us.
 * Caller leaves room for the headers (Ether, IP, UDP)
 */
ssize_t
readudp(d, pkt, len, tleft)
    struct iodesc *d;
    void *pkt;
    size_t len;
    time_t tleft;
{
    ssize_t n;
    size_t hlen;
    struct ip *ip;
    struct udphdr *uh;
    u_int16_t etype;    /* host order */

#ifdef NET_DEBUG
    if (debug)
        printf("readudp: called\n");
#endif

    uh = (struct udphdr *)pkt - 1;
    ip = (struct ip *)uh - 1;

    n = readether(d, ip, len + sizeof(*ip) + sizeof(*uh), tleft, &etype);
    if (n == -1 || n < sizeof(*ip) + sizeof(*uh))
        return -1;

    /* Ethernet address checks now in readether() */

    /* Need to respond to ARP requests. */
    if (etype == ETHERTYPE_ARP) {
        struct arphdr *ah = (void *)ip;
        if (ah->ar_op == htons(ARPOP_REQUEST)) {
            /* Send ARP reply */
            arp_reply(d, ah);
        }
        return -1;
    }

    if (etype != ETHERTYPE_IP) {
#ifdef NET_DEBUG
        if (debug)
            printf("readudp: not IP. ether_type=%x\n", etype);
#endif
        return -1;
    }

    /* Check ip header */
    if (ip->ip_v != IPVERSION ||
        ip->ip_p != IPPROTO_UDP) {  /* half char */
#ifdef NET_DEBUG
        if (debug)
            printf("readudp: IP version or not UDP. ip_v=%d ip_p=%d\n", ip->ip_v, ip->ip_p);
#endif
        return -1;
    }

    hlen = ip->ip_hl << 2;
    if (hlen < sizeof(*ip) ||
        in_cksum(ip, hlen) != 0) {
#ifdef NET_DEBUG
        if (debug)
            printf("readudp: short hdr or bad cksum.\n");
#endif
        return -1;
    }
    if (n < ntohs(ip->ip_len)) {
#ifdef NET_DEBUG
        if (debug)
            printf("readudp: bad length %d < %d.\n",
                   (int)n, ntohs(ip->ip_len));
#endif
        return -1;
    }
    if (d->myip.s_addr && ip->ip_dst.s_addr != d->myip.s_addr) {
#ifdef NET_DEBUG
        if (debug) {
            printf("readudp: bad saddr %s != ", inet_ntoa(d->myip));
            printf("%s\n", inet_ntoa(ip->ip_dst));
        }
#endif
        return -1;
    }

    /* If there were ip options, make them go away */
    if (hlen != sizeof(*ip)) {
        bcopy(((u_char *)ip) + hlen, uh, len - hlen);
        ip->ip_len = htons(sizeof(*ip));
        n -= hlen - sizeof(*ip);
    }
    if (uh->uh_dport != d->myport) {
#ifdef NET_DEBUG
        if (debug)
            printf("readudp: bad dport %d != %d\n",
                d->myport, ntohs(uh->uh_dport));
#endif
        return -1;
    }

#ifndef UDP_NO_CKSUM
    if (uh->uh_sum) {
        struct udpiphdr *ui;
        struct ip tip;

        n = ntohs(uh->uh_ulen) + sizeof(*ip);
        if (n > RECV_SIZE - ETHER_SIZE) {
            printf("readudp: huge packet, udp len %d\n", (int)n);
            return -1;
        }

        /* Check checksum (must save and restore ip header) */
        tip = *ip;
        ui = (struct udpiphdr *)ip;
        bzero(&ui->ui_x1, sizeof(ui->ui_x1));
        ui->ui_len = uh->uh_ulen;
        if (in_cksum(ui, n) != 0) {
#ifdef NET_DEBUG
            if (debug)
                printf("readudp: bad cksum\n");
#endif
            *ip = tip;
            return -1;
        }
        *ip = tip;
    }
#endif
    if (ntohs(uh->uh_ulen) < sizeof(*uh)) {
#ifdef NET_DEBUG
        if (debug)
            printf("readudp: bad udp len %d < %d\n",
                ntohs(uh->uh_ulen), (int)sizeof(*uh));
#endif
        return -1;
    }

    n = (n > (ntohs(uh->uh_ulen) - sizeof(*uh))) ?
        ntohs(uh->uh_ulen) - sizeof(*uh) : n;
    return (n);
}