V9/sys/inet.old/ip_input.c
/* ip_input.c 6.1 83/08/16 */
#include "../h/param.h"
#include "../h/systm.h"
#include "../h/stream.h"
#include "../h/inet/mbuf.h"
#include "../h/inet/in.h"
#include "../h/inet/ip.h"
#include "../h/inet/ip_var.h"
int ipqmaxlen = 50;
u_char ipcksum = 1;
struct ip *ip_reass();
/*
* 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.
*/
ip_input(m)
register struct mbuf *m;
{
register struct ip *ip;
register struct ipq *fp;
register int i;
int hlen;
if (m == 0)
return;
if (BLEN(m) < sizeof (struct ip) &&
(m = m_pullup(m, sizeof (struct ip))) == 0) {
ipstat.ips_toosmall++;
return;
}
ip = mtod(m, struct ip *);
if ((hlen = ip->ip_hl << 2) > BLEN(m)) {
if ((m = m_pullup(m, hlen)) == 0) {
ipstat.ips_badhlen++;
return;
}
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 = bp_len(m) - ip->ip_len;
if (i < 0) {
ipstat.ips_tooshort++;
goto bad;
}
if (i > 0)
m_adj(m, -i);
/*
* 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).
*/
ip->ip_dst = ntohl(ip->ip_dst);
ip->ip_src = ntohl(ip->ip_src);
if (hlen > sizeof (struct ip) && ip_dooptions(ip))
return;
if (ip_ifwithaddr(ip->ip_dst) == 0) {
ip_forward(ip);
return;
}
/*
* Look for queue of fragments
* of this datagram.
*/
if(ipq.next == 0 && ipq.prev == 0) /* init, only once */
ipq.next = ipq.prev = &ipq;
for (fp = ipq.next; fp != &ipq; fp = fp->next)
if (ip->ip_id == fp->ipq_id &&
ip->ip_src == fp->ipq_src &&
ip->ip_dst == fp->ipq_dst &&
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)
return;
hlen = ip->ip_hl << 2;
m = dtom(ip);
} else
if (fp)
ip_freef(fp);
/*
* Switch out to protocol's input routine.
*/
ipdrint(m, (unsigned int)(ip->ip_p));
return;
bad:
m_freem(m);
}
/*
* 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.
*/
struct ip *
ip_reass(ip, fp)
register struct ipasfrag *ip;
register struct ipq *fp;
{
register struct mbuf *m = dtom(ip);
register struct ipasfrag *q;
struct mbuf *t;
int hlen = ip->ip_hl << 2;
int i, next;
/*
* Presence of header sizes in mbufs
* would confuse code below.
*/
m->rptr += hlen;
/*
* If first fragment to arrive, create a reassembly queue.
*/
if (fp == 0) {
if ((t = m_get(M_WAIT, MT_FTABLE)) == NULL)
goto dropfrag;
t->m_next = 0;
fp = mtod(t, struct ipq *);
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;
m_adj(dtom(ip), i);
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);
}
insert:
/*
* Stick new segment in its place;
* check for complete reassembly.
*/
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);
t = m->m_next;
m->m_next = 0;
m_cat(m, t);
q = q->ipf_next;
while (q != (struct ipasfrag *)fp) {
t = dtom(q);
q = q->ipf_next;
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.
*/
ip = fp->ipq_next;
ip->ip_len = next;
((struct ip *)ip)->ip_src = fp->ipq_src;
((struct ip *)ip)->ip_dst = fp->ipq_dst;
remque(fp);
(void) m_free(dtom(fp));
m = dtom(ip);
m->rptr -= sizeof (struct ipasfrag);
return ((struct ip *)ip);
dropfrag:
m_freem(m);
return (0);
}
/*
* Free a fragment reassembly header and all
* associated datagrams.
*/
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));
}
remque(fp);
(void) m_free(dtom(fp));
}
/*
* Put an ip fragment on a reassembly chain.
* Like insque, but pointers in middle of structure.
*/
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.
*/
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 = spl6();
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);
}
timeout(ip_slowtimo, (caddr_t)0, hz);
splx(s);
}
#if NOTDEF
/* who calls this? */
/*
* Drain off all datagram fragments.
*/
ip_drain()
{
while (ipq.next != &ipq)
ip_freef(ipq.next);
}
#endif
/*
* Do option processing on a datagram,
* possibly discarding it if bad options
* are encountered.
*/
ip_dooptions(ip)
struct ip *ip;
{
register u_char *cp;
int opt, optlen, cnt;
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];
switch (opt) {
default:
break;
#ifdef FAT_CHANCE
/*
* 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;
ifp = if_ifwithaddr((struct sockaddr *)&ipaddr);
type = ICMP_UNREACH, code = ICMP_UNREACH_SRCFAIL;
if (ifp == 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 &&
if_ifonnetof(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 (ifinet == 0)
goto bad; /* ??? */
*sin++ = ((struct sockaddr_in *)&ifinet->if_addr)->sin_addr;
break;
case IPOPT_TS_PRESPEC:
ipaddr.sin_addr = *sin;
if (if_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;
#endif FATCHANCE
}
}
return (0);
}
/*
* 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) {
mopt->wptr = mopt->base + olen;
mopt->rptr = mopt->base;
bcopy((caddr_t)ip, mtod(m, caddr_t), (unsigned)olen);
}
i = BLEN(m) - (sizeof (struct ip) + olen);
bcopy((caddr_t)ip+olen, (caddr_t)ip, (unsigned)i);
m->wptr -= olen;
}
int ipforwarding = 1;
extern ipprintfs;
/*
* Forward a packet. If some error occurs return the sender
* and 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.
*/
ip_forward(ip)
register struct ip *ip;
{
struct mbuf *mopt;
if(ipprintfs)
printf("forward: src %x dst %x ttl %x\n", ip->ip_src,
ip->ip_dst, ip->ip_ttl);
if (ipforwarding == 0) {
m_freem(dtom(ip));
return;
}
if (ip->ip_ttl < IPTTLDEC) {
m_freem(dtom(ip));
return;
}
ip->ip_ttl -= IPTTLDEC;
mopt = m_get(M_DONTWAIT, MT_DATA);
if (mopt == NULL) {
m_freem(dtom(ip));
return;
}
mopt->next = 0;
ip_stripoptions(ip, mopt);
ip_output(dtom(ip), mopt, IP_FORWARDING);
}