Ultrix-3.1/sys/net/ip_input.c
/**********************************************************************
* Copyright (c) Digital Equipment Corporation 1984, 1985, 1986. *
* All Rights Reserved. *
* Reference "/usr/src/COPYRIGHT" for applicable restrictions. *
**********************************************************************/
/*
* Copyright (c) 1982 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*
* SCCSID: @(#)ip_input.c 3.0 4/21/86
* Based on: @(#)ip_input.c 6.11 (Berkeley) 6/8/85
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <errno.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include <netinet/tcp.h>
u_char ip_protox[IPPROTO_MAX];
int ipqmaxlen = IFQ_MAXLEN;
struct in_ifaddr *in_ifaddr; /* first inet address */
/*
* IP initialization: fill in IP protocol switch table.
* All protocols not implemented in kernel go to raw IP protocol handler.
*/
ip_init()
{
register struct protosw *pr;
register int i;
pr = pffindproto(PF_INET, IPPROTO_RAW);
if (pr == 0)
panic("ip_init");
for (i = 0; i < IPPROTO_MAX; i++)
ip_protox[i] = pr - inetsw;
for (pr = inetdomain.dom_protosw;
pr < inetdomain.dom_protoswNPROTOSW; pr++)
if (pr->pr_domain->dom_family == PF_INET &&
pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) {
if (pr->pr_protocol >= IPPROTO_MAX)
panic("ip_init: proto");
ip_protox[pr->pr_protocol] = pr - inetsw;
}
ipq.next = ipq.prev = &ipq;
#ifndef pdp11
ip_id = time.tv_sec & 0xffff;
#else pdp11
ip_id = time & 0xffff;
#endif pdp11
ipintrq.ifq_maxlen = ipqmaxlen;
}
u_char ipcksum = 1;
struct ip *ip_reass();
struct sockaddr_in ipaddr = { AF_INET };
/*
* Ip input routine. Checksum and byte swap header. If fragmented
* try to reassamble. If complete and fragment queue exists, discard.
* Process options. Pass to next level.
*/
ipintr()
{
register struct ip *ip;
register struct mbuf *m;
struct mbuf *m0;
register int i;
register struct ipq *fp;
register struct in_ifaddr *ia;
int hlen, s;
#ifdef pdp11
segm map;
saveseg5(map);
#endif pdp11
next:
/*
* Get next datagram off input queue and get IP header
* in first mbuf.
*/
s = splimp();
IF_DEQUEUE(&ipintrq, m);
splx(s);
if (m == 0) {
#ifdef pdp11
restorseg5(map);
#endif pdp11
return;
}
if ((m->m_off > MMAXOFF || m->m_len < sizeof (struct ip)) &&
(m = m_pullup(m, sizeof (struct ip))) == 0) {
ipstat.ips_toosmall++;
goto next;
}
ip = mtod(m, struct ip *);
hlen = ip->ip_hl << 2;
if (hlen < 10) { /* minimum header length */
ipstat.ips_badhlen++;
goto bad;
}
if (hlen > m->m_len) {
if ((m = m_pullup(m, hlen)) == 0) {
ipstat.ips_badhlen++;
goto next;
}
ip = mtod(m, struct ip *);
}
if (ipcksum)
if (ip->ip_sum = in_cksum(m, hlen)) {
ipstat.ips_badsum++;
goto bad;
}
/*
* Convert fields to host representation.
*/
ip->ip_len = ntohs((u_short)ip->ip_len);
if (ip->ip_len < hlen) {
ipstat.ips_badlen++;
goto bad;
}
ip->ip_id = ntohs(ip->ip_id);
ip->ip_off = ntohs((u_short)ip->ip_off);
/*
* Check that the amount of data in the buffers
* is as at least much as the IP header would have us expect.
* Trim mbufs if longer than we expect.
* Drop packet if shorter than we expect.
*/
i = -ip->ip_len;
m0 = m;
for (;;) {
i += m->m_len;
if (m->m_next == 0)
break;
m = m->m_next;
}
if (i != 0) {
if (i < 0) {
ipstat.ips_tooshort++;
m = m0;
goto bad;
}
if (i <= m->m_len)
m->m_len -= i;
else
m_adj(m0, -i);
}
m = m0;
/*
* Process options and, if not destined for us,
* ship it on. ip_dooptions returns 1 when an
* error was detected (causing an icmp message
* to be sent and the original packet to be freed).
*/
if (hlen > sizeof (struct ip) && ip_dooptions(ip))
goto next;
/*
* Check our list of addresses, to see if the packet is for us.
*/
for (ia = in_ifaddr; ia; ia = ia->ia_next) {
#define satosin(sa) ((struct sockaddr_in *)(sa))
if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
break;
if ((ia->ia_ifp->if_flags & IFF_BROADCAST) &&
satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
ip->ip_dst.s_addr)
break;
/*
* Look for all-0's host part (old broadcast addr).
*/
if ((ia->ia_ifp->if_flags & IFF_BROADCAST) &&
ia->ia_subnet == ntohl(ip->ip_dst.s_addr))
break;
}
if (ia == (struct in_ifaddr *)0) {
ip_forward(ip);
goto next;
}
/*
* Look for queue of fragments
* of this datagram.
*/
for (fp = ipq.next; fp != &ipq; fp = fp->next)
if (ip->ip_id == fp->ipq_id &&
ip->ip_src.s_addr == fp->ipq_src.s_addr &&
ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
ip->ip_p == fp->ipq_p)
goto found;
fp = 0;
found:
/*
* Adjust ip_len to not reflect header,
* set ip_mff if more fragments are expected,
* convert offset of this to bytes.
*/
ip->ip_len -= hlen;
((struct ipasfrag *)ip)->ipf_mff = 0;
if (ip->ip_off & IP_MF)
((struct ipasfrag *)ip)->ipf_mff = 1;
ip->ip_off <<= 3;
/*
* If datagram marked as having more fragments
* or if this is not the first fragment,
* attempt reassembly; if it succeeds, proceed.
*/
if (((struct ipasfrag *)ip)->ipf_mff || ip->ip_off) {
ip = ip_reass((struct ipasfrag *)ip, fp);
if (ip == 0)
goto next;
hlen = ip->ip_hl << 2;
m = dtom(ip);
} else
if (fp)
ip_freef(fp);
/*
* Switch out to protocol's input routine.
*/
#ifdef pdp11
if ((i = ip->ip_p) >= IPPROTO_MAX)
i = IPPROTO_psudoRAW;
(*inetsw[ip_protox[i]].pr_input)(m);
#else pdp11
(*inetsw[ip_protox[ip->ip_p]].pr_input)(m);
#endif pdp11
goto next;
bad:
m_freem(m);
goto next;
}
#ifdef pdp11
#define DTOM(q) ((q)->ipf_mbuf) /* the mbuf for this fragment */
#else
#define DTOM(q) dtom(q)
#endif
/*
* Take incoming datagram fragment and try to
* reassemble it into whole datagram. If a chain for
* reassembly of this datagram already exists, then it
* is given as fp; otherwise have to make a chain.
*/
static struct ip *
ip_reass(ip, fp)
register struct ipasfrag *ip;
register struct ipq *fp;
{
register struct mbuf *m = dtom(ip);
register struct ipasfrag *q;
#ifdef pdp11
register struct ipasfrag *ipf;
#endif pdp11
struct mbuf *t;
int hlen = ip->ip_hl << 2;
int i, next;
/*
* Presence of header sizes in mbufs
* would confuse code below.
*/
m->m_off += hlen;
m->m_len -= hlen;
/*
* If first fragment to arrive, create a reassembly queue.
*/
if (fp == 0) {
#ifdef vax
if ((t = m_get(M_WAIT, MT_FTABLE)) == NULL)
goto dropfrag;
fp = mtod(t, struct ipq *);
#else pdp11
MSGET(fp, struct ipq, MT_FTABLE, 0, M_DONTWAIT);
if (fp == NULL)
goto dropfrag;
#endif
insque(fp, &ipq);
fp->ipq_ttl = IPFRAGTTL;
fp->ipq_p = ip->ip_p;
fp->ipq_id = ip->ip_id;
fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp;
fp->ipq_src = ((struct ip *)ip)->ip_src;
fp->ipq_dst = ((struct ip *)ip)->ip_dst;
q = (struct ipasfrag *)fp;
goto insert;
}
/*
* Find a segment which begins after this one does.
*/
for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next)
if (q->ip_off > ip->ip_off)
break;
/*
* If there is a preceding segment, it may provide some of
* our data already. If so, drop the data from the incoming
* segment. If it provides all of our data, drop us.
*/
if (q->ipf_prev != (struct ipasfrag *)fp) {
i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off;
if (i > 0) {
if (i >= ip->ip_len)
goto dropfrag;
#ifdef vax
m_adj(dtom(ip), i);
#else pdp11
m_adj(m, i);
#endif
ip->ip_off += i;
ip->ip_len -= i;
}
}
/*
* While we overlap succeeding segments trim them or,
* if they are completely covered, dequeue them.
*/
while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) {
i = (ip->ip_off + ip->ip_len) - q->ip_off;
if (i < q->ip_len) {
q->ip_len -= i;
q->ip_off += i;
m_adj(DTOM(q), i);
break;
}
q = q->ipf_next;
m_freem(DTOM(q->ipf_prev));
ip_deq(q->ipf_prev);
#ifdef pdp11
MSFREE(q->ipf_prev);
#endif pdp11
}
insert:
/*
* Stick new segment in its place;
* check for complete reassembly.
*/
#ifdef pdp11
MSGET(ipf, struct ipasfrag, MT_FTABLE, 0, M_DONTWAIT);
if (ipf == 0)
goto dropfrag;
bcopy(ip, ipf, sizeof *ipf);
ipf->ipf_mbuf = m;
ip = ipf;
#endif
ip_enq(ip, q->ipf_prev);
next = 0;
for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) {
if (q->ip_off != next)
return (0);
next += q->ip_len;
}
if (q->ipf_prev->ipf_mff)
return (0);
/*
* Reassembly is complete; concatenate fragments.
*/
q = fp->ipq_next;
m = DTOM(q);
#ifdef pdp11
hlen = q->ip_hl << 2;
#endif pdp11
t = m->m_next;
m->m_next = 0;
m_cat(m, t);
#ifdef pdp11
ipf = q;
#endif pdp11
q = q->ipf_next;
#ifdef pdp11
MSFREE(ipf);
#endif pdp11
while (q != (struct ipasfrag *)fp) {
t = DTOM(q);
#ifdef pdp11
ipf = q;
#endif
q = q->ipf_next;
#ifdef pdp11
MSFREE(ipf);
#endif pdp11
m_cat(m, t);
}
/*
* Create header for new ip packet by
* modifying header of first packet;
* dequeue and discard fragment reassembly header.
* Make header visible.
*/
#ifdef vax
ip = fp->ipq_next;
#else pdp11
m->m_len += hlen;
m->m_off -= hlen;
ip = mtod(m, struct ipasfrag *);
#endif
ip->ip_len = next;
((struct ip *)ip)->ip_src = fp->ipq_src;
((struct ip *)ip)->ip_dst = fp->ipq_dst;
remque(fp);
#ifdef vax
(void) m_free(dtom(fp));
m = dtom(ip);
m->m_len += sizeof (struct ipasfrag);
m->m_off -= sizeof (struct ipasfrag);
#else pdp11
MSFREE(fp);
#endif pdp11
return ((struct ip *)ip);
dropfrag:
m_freem(m);
return (0);
}
/*
* Free a fragment reassembly header and all
* associated datagrams.
*/
static
ip_freef(fp)
struct ipq *fp;
{
register struct ipasfrag *q, *p;
for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) {
p = q->ipf_next;
ip_deq(q);
m_freem(DTOM(q));
#ifdef pdp11
MSFREE(q);
#endif pdp11
}
remque(fp);
#ifdef vax
(void) m_free(dtom(fp));
#else pdp11
MSFREE(fp);
#endif
}
/*
* Put an ip fragment on a reassembly chain.
* Like insque, but pointers in middle of structure.
*/
static
ip_enq(p, prev)
register struct ipasfrag *p, *prev;
{
p->ipf_prev = prev;
p->ipf_next = prev->ipf_next;
prev->ipf_next->ipf_prev = p;
prev->ipf_next = p;
}
/*
* To ip_enq as remque is to insque.
*/
static
ip_deq(p)
register struct ipasfrag *p;
{
p->ipf_prev->ipf_next = p->ipf_next;
p->ipf_next->ipf_prev = p->ipf_prev;
}
/*
* IP timer processing;
* if a timer expires on a reassembly
* queue, discard it.
*/
ip_slowtimo()
{
register struct ipq *fp;
int s = splnet();
fp = ipq.next;
if (fp == 0) {
splx(s);
return;
}
while (fp != &ipq) {
--fp->ipq_ttl;
fp = fp->next;
if (fp->prev->ipq_ttl == 0)
ip_freef(fp->prev);
}
splx(s);
}
/*
* Drain off all datagram fragments.
*/
ip_drain()
{
while (ipq.next != &ipq)
ip_freef(ipq.next);
}
/*
* Do option processing on a datagram,
* possibly discarding it if bad options
* are encountered.
*/
static
ip_dooptions(ip)
struct ip *ip;
{
register u_char *cp;
int opt, optlen, cnt, code, type;
struct in_addr *sin;
register struct ip_timestamp *ipt;
register struct ifaddr *ifa;
struct in_addr t;
cp = (u_char *)(ip + 1);
cnt = (ip->ip_hl << 2) - sizeof (struct ip);
for (; cnt > 0; cnt -= optlen, cp += optlen) {
opt = cp[0];
if (opt == IPOPT_EOL)
break;
if (opt == IPOPT_NOP)
optlen = 1;
else {
optlen = cp[1];
if (optlen <= 0 || optlen >= cnt)
goto bad;
}
switch (opt) {
default:
break;
/*
* Source routing with record.
* Find interface with current destination address.
* If none on this machine then drop if strictly routed,
* or do nothing if loosely routed.
* Record interface address and bring up next address
* component. If strictly routed make sure next
* address on directly accessible net.
*/
case IPOPT_LSRR:
case IPOPT_SSRR:
if (cp[2] < 4 || cp[2] > optlen - (sizeof (long) - 1))
break;
sin = (struct in_addr *)(cp + cp[2]);
ipaddr.sin_addr = *sin;
ifa = ifa_ifwithaddr((struct sockaddr *)&ipaddr);
type = ICMP_UNREACH, code = ICMP_UNREACH_SRCFAIL;
if (ifa == 0) {
if (opt == IPOPT_SSRR)
goto bad;
break;
}
t = ip->ip_dst; ip->ip_dst = *sin; *sin = t;
cp[2] += 4;
if (cp[2] > optlen - (sizeof (long) - 1))
break;
ip->ip_dst = sin[1];
if (opt == IPOPT_SSRR &&
in_iaonnetof(in_netof(ip->ip_dst)) == 0)
goto bad;
break;
case IPOPT_TS:
code = cp - (u_char *)ip;
type = ICMP_PARAMPROB;
ipt = (struct ip_timestamp *)cp;
if (ipt->ipt_len < 5)
goto bad;
if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) {
if (++ipt->ipt_oflw == 0)
goto bad;
break;
}
sin = (struct in_addr *)(cp+cp[2]);
switch (ipt->ipt_flg) {
case IPOPT_TS_TSONLY:
break;
case IPOPT_TS_TSANDADDR:
if (ipt->ipt_ptr + 8 > ipt->ipt_len)
goto bad;
if (in_ifaddr == 0)
goto bad; /* ??? */
*sin++ = IA_SIN(in_ifaddr)->sin_addr;
break;
case IPOPT_TS_PRESPEC:
ipaddr.sin_addr = *sin;
if (ifa_ifwithaddr((struct sockaddr *)&ipaddr) == 0)
continue;
if (ipt->ipt_ptr + 8 > ipt->ipt_len)
goto bad;
ipt->ipt_ptr += 4;
break;
default:
goto bad;
}
*(n_time *)sin = iptime();
ipt->ipt_ptr += 4;
}
}
return (0);
bad:
icmp_error(ip, type, code);
return (1);
}
/*
* Strip out IP options, at higher
* level protocol in the kernel.
* Second argument is buffer to which options
* will be moved, and return value is their length.
*/
ip_stripoptions(ip, mopt)
struct ip *ip;
struct mbuf *mopt;
{
register int i;
register struct mbuf *m;
int olen;
olen = (ip->ip_hl<<2) - sizeof (struct ip);
m = dtom(ip);
ip++;
if (mopt) {
#ifdef pdp11
MAPSAVE();
#endif pdp11
mopt->m_len = olen;
mopt->m_off = MMINOFF;
#ifndef pdp11
bcopy((caddr_t)ip, mtod(mopt, caddr_t), (unsigned)olen);
#else pdp11
if (olen)
MBCOPY(m, sizeof *ip, mopt, 0, olen);
MAPREST();
#endif pdp11
}
#ifdef pdp11
if (olen == 0)
return
#endif pdp11
i = m->m_len - (sizeof (struct ip) + olen);
bcopy((caddr_t)ip+olen, (caddr_t)ip, (unsigned)i);
m->m_len -= olen;
}
u_char inetctlerrmap[PRC_NCMDS] = {
ECONNABORTED, ECONNABORTED, 0, 0,
0, 0, EHOSTDOWN, EHOSTUNREACH,
ENETUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED,
EMSGSIZE, 0, 0, 0,
0, 0, 0, 0
};
int ipprintfs = 0;
int ipforwarding = 1;
/*
* Forward a packet. If some error occurs return the sender
* an icmp packet. Note we can't always generate a meaningful
* icmp message because icmp doesn't have a large enough repetoire
* of codes and types.
*/
static
ip_forward(ip)
register struct ip *ip;
{
register int error, type, code;
struct mbuf *mcopy;
#ifdef pdp11
struct mbuf *m = dtom(ip);
#endif pdp11
if (ipprintfs)
printf("forward: src %x dst %x ttl %x\n", ip->ip_src,
ip->ip_dst, ip->ip_ttl);
ip->ip_id = htons(ip->ip_id);
if (ipforwarding == 0) {
/* can't tell difference between net and host */
type = ICMP_UNREACH, code = ICMP_UNREACH_NET;
goto sendicmp;
}
if (ip->ip_ttl < IPTTLDEC) {
type = ICMP_TIMXCEED, code = ICMP_TIMXCEED_INTRANS;
goto sendicmp;
}
ip->ip_ttl -= IPTTLDEC;
/*
* Save at most 64 bytes of the packet in case
* we need to generate an ICMP message to the src.
*/
#ifdef vax
mcopy = m_copy(dtom(ip), 0, imin(ip->ip_len, 64));
#else pdp11
mcopy = m_copy(m, 0, MIN(ip->ip_len, 64));
#endif pdp11
#ifdef vax
error = ip_output(dtom(ip), (struct mbuf *)0, (struct route *)0,
IP_FORWARDING);
#else pdp11
error = ip_output(m, (struct mbuf *)0, (struct route *)0,
IP_FORWARDING);
#endif
if (error == 0) {
if (mcopy)
m_freem(mcopy);
ipstat.ips_forward++;
return;
}
ipstat.ips_cantforward++;
if (mcopy == NULL)
return;
ip = mtod(mcopy, struct ip *);
type = ICMP_UNREACH, code = 0; /* need ``undefined'' */
switch (error) {
case ENETUNREACH:
case ENETDOWN:
code = ICMP_UNREACH_NET;
break;
case EMSGSIZE:
code = ICMP_UNREACH_NEEDFRAG;
break;
case EPERM:
code = ICMP_UNREACH_PORT;
break;
case ENOBUFS:
type = ICMP_SOURCEQUENCH;
break;
case EHOSTDOWN:
case EHOSTUNREACH:
code = ICMP_UNREACH_HOST;
break;
}
sendicmp:
icmp_error(ip, type, code);
}