+/*
+ * 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.
+ */
+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;
+ if (ipprintfs)
+ printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
+
+#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 %X", ntohl(*mtod(m, struct in_addr *)));
+ 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;
+ if (ipprintfs)
+ printf(" %X\n", ntohl(*q));
+ }
+ /*
+ * Last hop goes to final destination.
+ */
+ *q = ip_srcrt.dst;
+#ifdef DIAGNOSTIC
+ if (ipprintfs)
+ printf(" %lx\n", ntohl(q->s_addr));
+#endif
+ return (m);
+}
+
projects / unix-history / blobdiff