diff options
Diffstat (limited to 'slirp/src/ip_input.c')
| -rw-r--r-- | slirp/src/ip_input.c | 471 |
1 files changed, 471 insertions, 0 deletions
diff --git a/slirp/src/ip_input.c b/slirp/src/ip_input.c new file mode 100644 index 0000000000..e0b94b0e42 --- /dev/null +++ b/slirp/src/ip_input.c @@ -0,0 +1,471 @@ +/* + * 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; + + if (!slirp->in_enabled) { + goto bad; + } + + DEBUG_CALL("ip_input"); + DEBUG_ARG("m = %p", m); + DEBUG_ARG("m_len = %d", m->m_len); + + if (m->m_len < sizeof (struct ip)) { + goto bad; + } + + ip = mtod(m, struct ip *); + + if (ip->ip_v != IPVERSION) { + goto bad; + } + + hlen = ip->ip_hl << 2; + if (hlen<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_send_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 = slirp->ipq.ip_link.next; l != &slirp->ipq.ip_link; + l = 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, AF_INET); + 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); +} + +#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 = %p", ip); + DEBUG_ARG("fp = %p", fp); + DEBUG_ARG("m = %p", 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 = fp->frag_link.next; q != (struct ipasfrag *)&fp->frag_link; + q = 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 = 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 = q->ipf_next; + m_free(dtom(slirp, q->ipf_prev)); + ip_deq(q->ipf_prev); + } + +insert: + /* + * Stick new segment in its place; + * check for complete reassembly. + */ + ip_enq(iptofrag(ip), q->ipf_prev); + next = 0; + for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link; + q = 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 = 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 = 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 = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link; q = p) { + p = 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 = %p", 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 = 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 = l->next; + if (--fp->ipq_ttl == 0) { + ip_freef(slirp, fp); + } + } +} + +/* + * 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 char *opts; + int olen; + + olen = (ip->ip_hl<<2) - sizeof (struct ip); + opts = (char *)(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; +} |