diff options
Diffstat (limited to 'sys/netinet/ip_input.c')
| -rw-r--r-- | sys/netinet/ip_input.c | 1166 |
1 files changed, 1166 insertions, 0 deletions
diff --git a/sys/netinet/ip_input.c b/sys/netinet/ip_input.c new file mode 100644 index 0000000..d3bfeac --- /dev/null +++ b/sys/netinet/ip_input.c @@ -0,0 +1,1166 @@ +/* + * 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. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 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. + * + * @(#)ip_input.c 8.2 (Berkeley) 1/4/94 + */ + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/malloc.h> +#include <sys/mbuf.h> +#include <sys/domain.h> +#include <sys/protosw.h> +#include <sys/socket.h> +#include <sys/errno.h> +#include <sys/time.h> +#include <sys/kernel.h> + +#include <net/if.h> +#include <net/route.h> + +#include <netinet/in.h> +#include <netinet/in_systm.h> +#include <netinet/ip.h> +#include <netinet/in_pcb.h> +#include <netinet/in_var.h> +#include <netinet/ip_var.h> +#include <netinet/ip_icmp.h> + +#ifndef IPFORWARDING +#ifdef GATEWAY +#define IPFORWARDING 1 /* forward IP packets not for us */ +#else /* GATEWAY */ +#define IPFORWARDING 0 /* don't forward IP packets not for us */ +#endif /* GATEWAY */ +#endif /* IPFORWARDING */ +#ifndef IPSENDREDIRECTS +#define IPSENDREDIRECTS 1 +#endif +int ipforwarding = IPFORWARDING; +int ipsendredirects = IPSENDREDIRECTS; +int ip_defttl = IPDEFTTL; +#ifdef DIAGNOSTIC +int ipprintfs = 0; +#endif + +extern struct domain inetdomain; +extern struct protosw inetsw[]; +u_char ip_protox[IPPROTO_MAX]; +int ipqmaxlen = IFQ_MAXLEN; +struct in_ifaddr *in_ifaddr; /* first inet address */ +struct ifqueue ipintrq; + +/* + * We need to save the IP options in case a protocol wants to respond + * to an incoming packet over the same route if the packet got here + * using IP source routing. This allows connection establishment and + * maintenance when the remote end is on a network that is not known + * to us. + */ +int ip_nhops = 0; +static struct ip_srcrt { + struct in_addr dst; /* final destination */ + char nop; /* one NOP to align */ + char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */ + struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)]; +} ip_srcrt; + +#ifdef GATEWAY +extern int if_index; +u_long *ip_ifmatrix; +#endif + +static void save_rte __P((u_char *, struct in_addr)); +/* + * IP initialization: fill in IP protocol switch table. + * All protocols not implemented in kernel go to raw IP protocol handler. + */ +void +ip_init() +{ + register struct protosw *pr; + register int i; + + pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_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) + ip_protox[pr->pr_protocol] = pr - inetsw; + ipq.next = ipq.prev = &ipq; + ip_id = time.tv_sec & 0xffff; + ipintrq.ifq_maxlen = ipqmaxlen; +#ifdef GATEWAY + i = (if_index + 1) * (if_index + 1) * sizeof (u_long); + ip_ifmatrix = (u_long *) malloc(i, M_RTABLE, M_WAITOK); + bzero((char *)ip_ifmatrix, i); +#endif +} + +struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; +struct route ipforward_rt; + +/* + * Ip input routine. Checksum and byte swap header. If fragmented + * try to reassemble. Process options. Pass to next level. + */ +void +ipintr() +{ + register struct ip *ip; + register struct mbuf *m; + register struct ipq *fp; + register struct in_ifaddr *ia; + int hlen, s; + +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) + return; +#ifdef DIAGNOSTIC + if ((m->m_flags & M_PKTHDR) == 0) + panic("ipintr no HDR"); +#endif + /* + * If no IP addresses have been set yet but the interfaces + * are receiving, can't do anything with incoming packets yet. + */ + if (in_ifaddr == NULL) + goto bad; + ipstat.ips_total++; + if (m->m_len < sizeof (struct ip) && + (m = m_pullup(m, sizeof (struct ip))) == 0) { + ipstat.ips_toosmall++; + goto next; + } + ip = mtod(m, struct ip *); + if (ip->ip_v != IPVERSION) { + ipstat.ips_badvers++; + goto bad; + } + hlen = ip->ip_hl << 2; + if (hlen < sizeof(struct ip)) { /* 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 (ip->ip_sum = in_cksum(m, hlen)) { + ipstat.ips_badsum++; + goto bad; + } + + /* + * Convert fields to host representation. + */ + NTOHS(ip->ip_len); + if (ip->ip_len < hlen) { + ipstat.ips_badlen++; + 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_pkthdr.len < ip->ip_len) { + ipstat.ips_tooshort++; + goto bad; + } + if (m->m_pkthdr.len > ip->ip_len) { + if (m->m_len == m->m_pkthdr.len) { + m->m_len = ip->ip_len; + m->m_pkthdr.len = ip->ip_len; + } else + m_adj(m, ip->ip_len - m->m_pkthdr.len); + } + + /* + * 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). + */ + ip_nhops = 0; /* for source routed packets */ + if (hlen > sizeof (struct ip) && ip_dooptions(m)) + 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) + goto ours; + if ( +#ifdef DIRECTED_BROADCAST + ia->ia_ifp == m->m_pkthdr.rcvif && +#endif + (ia->ia_ifp->if_flags & IFF_BROADCAST)) { + u_long t; + + if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == + ip->ip_dst.s_addr) + goto ours; + if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr) + goto ours; + /* + * Look for all-0's host part (old broadcast addr), + * either for subnet or net. + */ + t = ntohl(ip->ip_dst.s_addr); + if (t == ia->ia_subnet) + goto ours; + if (t == ia->ia_net) + goto ours; + } + } + if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) { + struct in_multi *inm; +#ifdef MROUTING + extern struct socket *ip_mrouter; + + if (ip_mrouter) { + /* + * If we are acting as a multicast router, all + * incoming multicast packets are passed to the + * kernel-level multicast forwarding function. + * The packet is returned (relatively) intact; if + * ip_mforward() returns a non-zero value, the packet + * must be discarded, else it may be accepted below. + * + * (The IP ident field is put in the same byte order + * as expected when ip_mforward() is called from + * ip_output().) + */ + ip->ip_id = htons(ip->ip_id); + if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) { + ipstat.ips_cantforward++; + m_freem(m); + goto next; + } + ip->ip_id = ntohs(ip->ip_id); + + /* + * The process-level routing demon needs to receive + * all multicast IGMP packets, whether or not this + * host belongs to their destination groups. + */ + if (ip->ip_p == IPPROTO_IGMP) + goto ours; + ipstat.ips_forward++; + } +#endif + /* + * See if we belong to the destination multicast group on the + * arrival interface. + */ + IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm); + if (inm == NULL) { + ipstat.ips_cantforward++; + m_freem(m); + goto next; + } + goto ours; + } + if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) + goto ours; + if (ip->ip_dst.s_addr == INADDR_ANY) + goto ours; + + /* + * Not for us; forward if possible and desirable. + */ + if (ipforwarding == 0) { + ipstat.ips_cantforward++; + m_freem(m); + } else + ip_forward(m, 0); + goto next; + +ours: + /* + * 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.) + */ + if (ip->ip_off &~ IP_DF) { + if (m->m_flags & M_EXT) { /* XXX */ + if ((m = m_pullup(m, sizeof (struct ip))) == 0) { + ipstat.ips_toosmall++; + goto next; + } + ip = mtod(m, struct ip *); + } + /* + * 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 &= ~1; + 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 & 1 || ip->ip_off) { + ipstat.ips_fragments++; + ip = ip_reass((struct ipasfrag *)ip, fp); + if (ip == 0) + goto next; + ipstat.ips_reassembled++; + m = dtom(ip); + } else + if (fp) + ip_freef(fp); + } else + ip->ip_len -= hlen; + + /* + * Switch out to protocol's input routine. + */ + ipstat.ips_delivered++; + (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); + goto next; +bad: + m_freem(m); + goto next; +} + +/* + * 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->m_data += hlen; + m->m_len -= hlen; + + /* + * If first fragment to arrive, create a reassembly queue. + */ + if (fp == 0) { + if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL) + goto dropfrag; + 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 & 1) + 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; + ip->ipf_mff &= ~1; + ((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->m_len += (ip->ip_hl << 2); + m->m_data -= (ip->ip_hl << 2); + /* some debugging cruft by sklower, below, will go away soon */ + if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ + register int plen = 0; + for (t = m; m; m = m->m_next) + plen += m->m_len; + t->m_pkthdr.len = plen; + } + return ((struct ip *)ip); + +dropfrag: + ipstat.ips_fragdropped++; + m_freem(m); + return (0); +} + +/* + * Free a fragment reassembly header and all + * associated datagrams. + */ +void +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. + */ +void +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. + */ +void +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. + */ +void +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) { + ipstat.ips_fragtimeout++; + ip_freef(fp->prev); + } + } + splx(s); +} + +/* + * Drain off all datagram fragments. + */ +void +ip_drain() +{ + + while (ipq.next != &ipq) { + ipstat.ips_fragdropped++; + ip_freef(ipq.next); + } +} + +/* + * 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. + */ +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 = ICMP_PARAMPROB, forward = 0; + struct in_addr *sin, dst; + 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 (long)) { + 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_ifpforaddr((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: + ip->ip_len -= ip->ip_hl << 2; /* XXX icmp_error adds in hdr length */ + icmp_error(m, type, code, 0, 0); + ipstat.ips_badoptions++; + return (1); +} + +/* + * Given address of next destination (final or next hop), + * return internet address info of interface to be used to get there. + */ +struct in_ifaddr * +ip_rtaddr(dst) + struct in_addr dst; +{ + register struct sockaddr_in *sin; + + sin = (struct sockaddr_in *) &ipforward_rt.ro_dst; + + if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) { + if (ipforward_rt.ro_rt) { + RTFREE(ipforward_rt.ro_rt); + ipforward_rt.ro_rt = 0; + } + sin->sin_family = AF_INET; + sin->sin_len = sizeof(*sin); + sin->sin_addr = dst; + + rtalloc(&ipforward_rt); + } + if (ipforward_rt.ro_rt == 0) + return ((struct in_ifaddr *)0); + return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa); +} + +/* + * Save incoming source route for use in replies, + * to be picked up later by ip_srcroute if the receiver is interested. + */ +void +save_rte(option, dst) + u_char *option; + struct in_addr dst; +{ + unsigned olen; + + olen = option[IPOPT_OLEN]; +#ifdef DIAGNOSTIC + if (ipprintfs) + printf("save_rte: olen %d\n", olen); +#endif + if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst))) + return; + bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen); + ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); + ip_srcrt.dst = dst; +} + +/* + * Retrieve incoming source route for use in replies, + * in the same form used by setsockopt. + * The first hop is placed before the options, will be removed later. + */ +struct mbuf * +ip_srcroute() +{ + register struct in_addr *p, *q; + register struct mbuf *m; + + if (ip_nhops == 0) + return ((struct mbuf *)0); + m = m_get(M_DONTWAIT, MT_SOOPTS); + if (m == 0) + return ((struct mbuf *)0); + +#define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt)) + + /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ + m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) + + OPTSIZ; +#ifdef DIAGNOSTIC + if (ipprintfs) + printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len); +#endif + + /* + * First save first hop for return route + */ + p = &ip_srcrt.route[ip_nhops - 1]; + *(mtod(m, struct in_addr *)) = *p--; +#ifdef DIAGNOSTIC + if (ipprintfs) + printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr)); +#endif + + /* + * Copy option fields and padding (nop) to mbuf. + */ + ip_srcrt.nop = IPOPT_NOP; + ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; + bcopy((caddr_t)&ip_srcrt.nop, + mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ); + q = (struct in_addr *)(mtod(m, caddr_t) + + sizeof(struct in_addr) + OPTSIZ); +#undef OPTSIZ + /* + * Record return path as an IP source route, + * reversing the path (pointers are now aligned). + */ + while (p >= ip_srcrt.route) { +#ifdef DIAGNOSTIC + if (ipprintfs) + printf(" %lx", ntohl(q->s_addr)); +#endif + *q++ = *p--; + } + /* + * Last hop goes to final destination. + */ + *q = ip_srcrt.dst; +#ifdef DIAGNOSTIC + if (ipprintfs) + printf(" %lx\n", ntohl(q->s_addr)); +#endif + return (m); +} + +/* + * 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(m, mopt) + 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); + bcopy(opts + olen, opts, (unsigned)i); + m->m_len -= olen; + if (m->m_flags & M_PKTHDR) + m->m_pkthdr.len -= olen; + ip->ip_hl = sizeof(struct ip) >> 2; +} + +u_char inetctlerrmap[PRC_NCMDS] = { + 0, 0, 0, 0, + 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, + EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, + EMSGSIZE, EHOSTUNREACH, 0, 0, + 0, 0, 0, 0, + ENOPROTOOPT +}; + +/* + * 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 repertoire + * of codes and types. + * + * If not forwarding, just drop the packet. This could be confusing + * if ipforwarding was zero but some routing protocol was advancing + * us as a gateway to somewhere. However, we must let the routing + * protocol deal with that. + * + * The srcrt parameter indicates whether the packet is being forwarded + * via a source route. + */ +void +ip_forward(m, srcrt) + struct mbuf *m; + int srcrt; +{ + register struct ip *ip = mtod(m, struct ip *); + register struct sockaddr_in *sin; + register struct rtentry *rt; + int error, type = 0, code; + struct mbuf *mcopy; + n_long dest; + struct ifnet *destifp; + + dest = 0; +#ifdef DIAGNOSTIC + if (ipprintfs) + printf("forward: src %x dst %x ttl %x\n", ip->ip_src, + ip->ip_dst, ip->ip_ttl); +#endif + if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) { + ipstat.ips_cantforward++; + m_freem(m); + return; + } + HTONS(ip->ip_id); + if (ip->ip_ttl <= IPTTLDEC) { + icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0); + return; + } + ip->ip_ttl -= IPTTLDEC; + + sin = (struct sockaddr_in *)&ipforward_rt.ro_dst; + if ((rt = ipforward_rt.ro_rt) == 0 || + ip->ip_dst.s_addr != sin->sin_addr.s_addr) { + if (ipforward_rt.ro_rt) { + RTFREE(ipforward_rt.ro_rt); + ipforward_rt.ro_rt = 0; + } + sin->sin_family = AF_INET; + sin->sin_len = sizeof(*sin); + sin->sin_addr = ip->ip_dst; + + rtalloc(&ipforward_rt); + if (ipforward_rt.ro_rt == 0) { + icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0); + return; + } + rt = ipforward_rt.ro_rt; + } + + /* + * Save at most 64 bytes of the packet in case + * we need to generate an ICMP message to the src. + */ + mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64)); + +#ifdef GATEWAY + ip_ifmatrix[rt->rt_ifp->if_index + + if_index * m->m_pkthdr.rcvif->if_index]++; +#endif + /* + * If forwarding packet using same interface that it came in on, + * perhaps should send a redirect to sender to shortcut a hop. + * Only send redirect if source is sending directly to us, + * and if packet was not source routed (or has any options). + * Also, don't send redirect if forwarding using a default route + * or a route modified by a redirect. + */ +#define satosin(sa) ((struct sockaddr_in *)(sa)) + if (rt->rt_ifp == m->m_pkthdr.rcvif && + (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && + satosin(rt_key(rt))->sin_addr.s_addr != 0 && + ipsendredirects && !srcrt) { +#define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) + u_long src = ntohl(ip->ip_src.s_addr); + + if (RTA(rt) && + (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) { + if (rt->rt_flags & RTF_GATEWAY) + dest = satosin(rt->rt_gateway)->sin_addr.s_addr; + else + dest = ip->ip_dst.s_addr; + /* Router requirements says to only send host redirects */ + type = ICMP_REDIRECT; + code = ICMP_REDIRECT_HOST; +#ifdef DIAGNOSTIC + if (ipprintfs) + printf("redirect (%d) to %lx\n", code, (u_long)dest); +#endif + } + } + + error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING +#ifdef DIRECTED_BROADCAST + | IP_ALLOWBROADCAST +#endif + , 0); + if (error) + ipstat.ips_cantforward++; + else { + ipstat.ips_forward++; + if (type) + ipstat.ips_redirectsent++; + else { + if (mcopy) + m_freem(mcopy); + return; + } + } + if (mcopy == NULL) + return; + destifp = NULL; + + switch (error) { + + case 0: /* forwarded, but need redirect */ + /* type, code set above */ + break; + + case ENETUNREACH: /* shouldn't happen, checked above */ + case EHOSTUNREACH: + case ENETDOWN: + case EHOSTDOWN: + default: + type = ICMP_UNREACH; + code = ICMP_UNREACH_HOST; + break; + + case EMSGSIZE: + type = ICMP_UNREACH; + code = ICMP_UNREACH_NEEDFRAG; + if (ipforward_rt.ro_rt) + destifp = ipforward_rt.ro_rt->rt_ifp; + ipstat.ips_cantfrag++; + break; + + case ENOBUFS: + type = ICMP_SOURCEQUENCH; + code = 0; + break; + } + icmp_error(mcopy, type, code, dest, destifp); +} + +int +ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen) + int *name; + u_int namelen; + void *oldp; + size_t *oldlenp; + void *newp; + size_t newlen; +{ + /* All sysctl names at this level are terminal. */ + if (namelen != 1) + return (ENOTDIR); + + switch (name[0]) { + case IPCTL_FORWARDING: + return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding)); + case IPCTL_SENDREDIRECTS: + return (sysctl_int(oldp, oldlenp, newp, newlen, + &ipsendredirects)); + case IPCTL_DEFTTL: + return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl)); +#ifdef notyet + case IPCTL_DEFMTU: + return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu)); +#endif + default: + return (EOPNOTSUPP); + } + /* NOTREACHED */ +} |
