/* * Copyright (c) 1982, 1986, 1988, 1993 * The Regents of the University of California. All rights reserved. * * 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. * 3. 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. * * @(#)ip_input.c 8.2 (Berkeley) 1/4/94 * ip_input.c,v 1.11 1994/11/16 10:17:08 jkh Exp */ /* * Changes and additions relating to SLiRP are * Copyright (c) 1995 Danny Gasparovski. * * Please read the file COPYRIGHT for the * terms and conditions of the copyright. */ #include "slirp.h" #include "ip_icmp.h" static struct ip *ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp); static void ip_freef(Slirp *slirp, struct ipq *fp); static void ip_enq(register struct ipasfrag *p, register struct ipasfrag *prev); static void ip_deq(register struct ipasfrag *p); /* * IP initialization: fill in IP protocol switch table. * All protocols not implemented in kernel go to raw IP protocol handler. */ void ip_init(Slirp *slirp) { slirp->ipq.ip_link.next = slirp->ipq.ip_link.prev = &slirp->ipq.ip_link; udp_init(slirp); tcp_init(slirp); icmp_init(slirp); } void ip_cleanup(Slirp *slirp) { udp_cleanup(slirp); tcp_cleanup(slirp); icmp_cleanup(slirp); } /* * Ip input routine. Checksum and byte swap header. If fragmented * try to reassemble. Process options. Pass to next level. */ void ip_input(struct mbuf *m) { Slirp *slirp = m->slirp; register struct ip *ip; int hlen; DEBUG_CALL("ip_input"); DEBUG_ARG("m = %lx", (long)m); DEBUG_ARG("m_len = %d", m->m_len); if (m->m_len < (int)sizeof(struct ip)) { return; } ip = mtod(m, struct ip *); if (ip->ip_v != IPVERSION) { goto bad; } hlen = ip->ip_hl << 2; if (hlen < (int)sizeof(struct ip) || hlen>m->m_len) {/* min header length */ goto bad; /* or packet too short */ } /* keep ip header intact for ICMP reply * ip->ip_sum = cksum(m, hlen); * if (ip->ip_sum) { */ if(cksum(m,hlen)) { goto bad; } /* * Convert fields to host representation. */ NTOHS(ip->ip_len); if (ip->ip_len < hlen) { goto bad; } NTOHS(ip->ip_id); NTOHS(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. */ if (m->m_len < ip->ip_len) { goto bad; } /* Should drop packet if mbuf too long? hmmm... */ if (m->m_len > ip->ip_len) m_adj(m, ip->ip_len - m->m_len); /* check ip_ttl for a correct ICMP reply */ if(ip->ip_ttl==0) { icmp_error(m, ICMP_TIMXCEED,ICMP_TIMXCEED_INTRANS, 0,"ttl"); goto bad; } /* * If offset or IP_MF are set, must reassemble. * Otherwise, nothing need be done. * (We could look in the reassembly queue to see * if the packet was previously fragmented, * but it's not worth the time; just let them time out.) * * XXX This should fail, don't fragment yet */ if (ip->ip_off &~ IP_DF) { register struct ipq *fp; struct qlink *l; /* * Look for queue of fragments * of this datagram. */ for (l = (qlink*)slirp->ipq.ip_link.next; l != &slirp->ipq.ip_link; l = (qlink*)l->next) { fp = container_of(l, struct ipq, ip_link); 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 = NULL; 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; if (ip->ip_off & IP_MF) ip->ip_tos |= 1; else ip->ip_tos &= ~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 (ip->ip_tos & 1 || ip->ip_off) { ip = ip_reass(slirp, ip, fp); if (ip == NULL) return; m = dtom(slirp, ip); } else if (fp) ip_freef(slirp, fp); } else ip->ip_len -= hlen; /* * Switch out to protocol's input routine. */ switch (ip->ip_p) { case IPPROTO_TCP: tcp_input(m, hlen, (struct socket *)NULL); break; case IPPROTO_UDP: udp_input(m, hlen); break; case IPPROTO_ICMP: icmp_input(m, hlen); break; default: m_free(m); } return; bad: m_free(m); return; } #define iptofrag(P) ((struct ipasfrag *)(((char*)(P)) - sizeof(struct qlink))) #define fragtoip(P) ((struct ip*)(((char*)(P)) + sizeof(struct qlink))) /* * 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(Slirp *slirp, struct ip *ip, struct ipq *fp) { register struct mbuf *m = dtom(slirp, ip); register struct ipasfrag *q; int hlen = ip->ip_hl << 2; int i, next; DEBUG_CALL("ip_reass"); DEBUG_ARG("ip = %lx", (long)ip); DEBUG_ARG("fp = %lx", (long)fp); DEBUG_ARG("m = %lx", (long)m); /* * Presence of header sizes in mbufs * would confuse code below. * Fragment m_data is concatenated. */ m->m_data += hlen; m->m_len -= hlen; /* * If first fragment to arrive, create a reassembly queue. */ if (fp == NULL) { struct mbuf *t = m_get(slirp); if (t == NULL) { goto dropfrag; } fp = mtod(t, struct ipq *); insque(&fp->ip_link, &slirp->ipq.ip_link); fp->ipq_ttl = IPFRAGTTL; fp->ipq_p = ip->ip_p; fp->ipq_id = ip->ip_id; fp->frag_link.next = fp->frag_link.prev = &fp->frag_link; fp->ipq_src = ip->ip_src; fp->ipq_dst = ip->ip_dst; q = (struct ipasfrag *)fp; goto insert; } /* * Find a segment which begins after this one does. */ for (q = (struct ipasfrag *)fp->frag_link.next; q != (struct ipasfrag *)&fp->frag_link; q = (struct ipasfrag *)q->ipf_next) if (q->ipf_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 != &fp->frag_link) { struct ipasfrag *pq = (struct ipasfrag*)q->ipf_prev; i = pq->ipf_off + pq->ipf_len - ip->ip_off; if (i > 0) { if (i >= ip->ip_len) goto dropfrag; m_adj(dtom(slirp, 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->frag_link && ip->ip_off + ip->ip_len > q->ipf_off) { i = (ip->ip_off + ip->ip_len) - q->ipf_off; if (i < q->ipf_len) { q->ipf_len -= i; q->ipf_off += i; m_adj(dtom(slirp, q), i); break; } q = (struct ipasfrag*)q->ipf_next; m_free(dtom(slirp, q->ipf_prev)); ip_deq((struct ipasfrag*)q->ipf_prev); } insert: /* * Stick new segment in its place; * check for complete reassembly. */ ip_enq(iptofrag(ip), (struct ipasfrag*)q->ipf_prev); next = 0; for (q = (struct ipasfrag*)fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link; q = (struct ipasfrag*)q->ipf_next) { if (q->ipf_off != next) return NULL; next += q->ipf_len; } if (((struct ipasfrag *)(q->ipf_prev))->ipf_tos & 1) return NULL; /* * Reassembly is complete; concatenate fragments. */ q = (struct ipasfrag *)fp->frag_link.next; m = dtom(slirp, q); q = (struct ipasfrag *) q->ipf_next; while (q != (struct ipasfrag*)&fp->frag_link) { struct mbuf *t = dtom(slirp, q); q = (struct ipasfrag *) 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. */ q = (struct ipasfrag *)fp->frag_link.next; /* * If the fragments concatenated to an mbuf that's * bigger than the total size of the fragment, then and * m_ext buffer was alloced. But fp->ipq_next points to * the old buffer (in the mbuf), so we must point ip * into the new buffer. */ if (m->m_flags & M_EXT) { int delta = (char *)q - m->m_dat; q = (struct ipasfrag *)(m->m_ext + delta); } ip = fragtoip(q); ip->ip_len = next; ip->ip_tos &= ~1; ip->ip_src = fp->ipq_src; ip->ip_dst = fp->ipq_dst; remque(&fp->ip_link); (void) m_free(dtom(slirp, fp)); m->m_len += (ip->ip_hl << 2); m->m_data -= (ip->ip_hl << 2); return ip; dropfrag: m_free(m); return NULL; } /* * Free a fragment reassembly header and all * associated datagrams. */ static void ip_freef(Slirp *slirp, struct ipq *fp) { register struct ipasfrag *q, *p; for (q = (struct ipasfrag *)fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link; q = p) { p = (struct ipasfrag *)q->ipf_next; ip_deq(q); m_free(dtom(slirp, q)); } remque(&fp->ip_link); (void) m_free(dtom(slirp, fp)); } /* * Put an ip fragment on a reassembly chain. * Like insque, but pointers in middle of structure. */ static void ip_enq(register struct ipasfrag *p, register struct ipasfrag *prev) { DEBUG_CALL("ip_enq"); DEBUG_ARG("prev = %lx", (long)prev); p->ipf_prev = prev; p->ipf_next = prev->ipf_next; ((struct ipasfrag *)(prev->ipf_next))->ipf_prev = p; prev->ipf_next = p; } /* * To ip_enq as remque is to insque. */ static void ip_deq(register struct ipasfrag *p) { ((struct ipasfrag *)(p->ipf_prev))->ipf_next = p->ipf_next; ((struct ipasfrag *)(p->ipf_next))->ipf_prev = p->ipf_prev; } /* * IP timer processing; * if a timer expires on a reassembly * queue, discard it. */ void ip_slowtimo(Slirp *slirp) { struct qlink *l; DEBUG_CALL("ip_slowtimo"); l = (struct qlink*)slirp->ipq.ip_link.next; if (l == NULL) return; while (l != &slirp->ipq.ip_link) { struct ipq *fp = container_of(l, struct ipq, ip_link); l = (struct qlink*)l->next; if (--fp->ipq_ttl == 0) { ip_freef(slirp, fp); } } } /* * Do option processing on a datagram, * possibly discarding it if bad options are encountered, * or forwarding it if source-routed. * Returns 1 if packet has been forwarded/freed, * 0 if the packet should be processed further. */ #ifdef notdef int ip_dooptions(m) struct mbuf *m; { register struct ip *ip = mtod(m, struct ip *); register u_char *cp; register struct ip_timestamp *ipt; register struct in_ifaddr *ia; int opt, optlen, cnt, off, code, type, forward = 0; struct in_addr *sin, dst; typedef uint32_t n_time; n_time ntime; dst = ip->ip_dst; cp = (u_char *)(ip + 1); cnt = (ip->ip_hl << 2) - sizeof (struct ip); for (; cnt > 0; cnt -= optlen, cp += optlen) { opt = cp[IPOPT_OPTVAL]; if (opt == IPOPT_EOL) break; if (opt == IPOPT_NOP) optlen = 1; else { optlen = cp[IPOPT_OLEN]; if (optlen <= 0 || optlen > cnt) { code = &cp[IPOPT_OLEN] - (u_char *)ip; 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 is on directly accessible net. */ case IPOPT_LSRR: case IPOPT_SSRR: if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } ipaddr.sin_addr = ip->ip_dst; ia = (struct in_ifaddr *) ifa_ifwithaddr((struct sockaddr *)&ipaddr); if (ia == 0) { if (opt == IPOPT_SSRR) { type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; goto bad; } /* * Loose routing, and not at next destination * yet; nothing to do except forward. */ break; } off--; /* 0 origin */ if (off > optlen - sizeof(struct in_addr)) { /* * End of source route. Should be for us. */ save_rte(cp, ip->ip_src); break; } /* * locate outgoing interface */ bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr, sizeof(ipaddr.sin_addr)); if (opt == IPOPT_SSRR) { #define INA struct in_ifaddr * #define SA struct sockaddr * if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0) ia = (INA)ifa_ifwithnet((SA)&ipaddr); } else ia = ip_rtaddr(ipaddr.sin_addr); if (ia == 0) { type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; goto bad; } ip->ip_dst = ipaddr.sin_addr; bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), (caddr_t)(cp + off), sizeof(struct in_addr)); cp[IPOPT_OFFSET] += sizeof(struct in_addr); /* * Let ip_intr's mcast routing check handle mcast pkts */ forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr)); break; case IPOPT_RR: if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } /* * If no space remains, ignore. */ off--; /* 0 origin */ if (off > optlen - sizeof(struct in_addr)) break; bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr, sizeof(ipaddr.sin_addr)); /* * locate outgoing interface; if we're the destination, * use the incoming interface (should be same). */ if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 && (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) { type = ICMP_UNREACH; code = ICMP_UNREACH_HOST; goto bad; } bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), (caddr_t)(cp + off), sizeof(struct in_addr)); cp[IPOPT_OFFSET] += sizeof(struct in_addr); break; case IPOPT_TS: code = cp - (u_char *)ip; ipt = (struct ip_timestamp *)cp; if (ipt->ipt_len < 5) goto bad; if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) { if (++ipt->ipt_oflw == 0) goto bad; break; } sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1); switch (ipt->ipt_flg) { case IPOPT_TS_TSONLY: break; case IPOPT_TS_TSANDADDR: if (ipt->ipt_ptr + sizeof(n_time) + sizeof(struct in_addr) > ipt->ipt_len) goto bad; ipaddr.sin_addr = dst; ia = (INA)ifaof_ i f p foraddr((SA)&ipaddr, m->m_pkthdr.rcvif); if (ia == 0) continue; bcopy((caddr_t)&IA_SIN(ia)->sin_addr, (caddr_t)sin, sizeof(struct in_addr)); ipt->ipt_ptr += sizeof(struct in_addr); break; case IPOPT_TS_PRESPEC: if (ipt->ipt_ptr + sizeof(n_time) + sizeof(struct in_addr) > ipt->ipt_len) goto bad; bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr, sizeof(struct in_addr)); if (ifa_ifwithaddr((SA)&ipaddr) == 0) continue; ipt->ipt_ptr += sizeof(struct in_addr); break; default: goto bad; } ntime = iptime(); bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1, sizeof(n_time)); ipt->ipt_ptr += sizeof(n_time); } } if (forward) { ip_forward(m, 1); return (1); } return (0); bad: icmp_error(m, type, code, 0, 0); return (1); } #endif /* notdef */ /* * 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. * (XXX) should be deleted; last arg currently ignored. */ void ip_stripoptions(register struct mbuf *m, struct mbuf *mopt) { register int i; struct ip *ip = mtod(m, struct ip *); register caddr_t opts; int olen; olen = (ip->ip_hl<<2) - sizeof (struct ip); opts = (caddr_t)(ip + 1); i = m->m_len - (sizeof (struct ip) + olen); memcpy(opts, opts + olen, (unsigned)i); m->m_len -= olen; ip->ip_hl = sizeof(struct ip) >> 2; }