| 1 | /* ip_icmp.c 4.13 82/04/07 */ |
| 2 | |
| 3 | #include "../h/param.h" |
| 4 | #include "../h/systm.h" |
| 5 | #include "../h/mbuf.h" |
| 6 | #include "../h/protosw.h" |
| 7 | #include "../h/clock.h" |
| 8 | #include "../net/in.h" |
| 9 | #include "../net/in_systm.h" |
| 10 | #include "../net/ip.h" |
| 11 | #include "../net/ip_icmp.h" |
| 12 | |
| 13 | /* |
| 14 | * ICMP routines: error generation, receive packet processing, and |
| 15 | * routines to turnaround packets back to the originator, and |
| 16 | * host table maintenance routines. |
| 17 | */ |
| 18 | |
| 19 | /* |
| 20 | * Generate an error packet of type error in response to bad packet ip. |
| 21 | */ |
| 22 | icmp_error(oip, type, code) |
| 23 | struct ip *oip; |
| 24 | int type; |
| 25 | { |
| 26 | unsigned oiplen = oip->ip_hl << 2; |
| 27 | struct icmp *icp = (struct icmp *)((int)oip + oiplen); |
| 28 | struct mbuf *m; |
| 29 | struct ip *nip; |
| 30 | COUNT(ICMP_ERROR); |
| 31 | |
| 32 | /* |
| 33 | * Make sure that the old IP packet had 8 bytes of data to return; |
| 34 | * if not, don't bother. Also don't EVER error if the old |
| 35 | * packet protocol was ICMP. |
| 36 | */ |
| 37 | if (oip->ip_len - oiplen < 8 || oip->ip_p == IPPROTO_ICMP) |
| 38 | goto free; |
| 39 | |
| 40 | /* |
| 41 | * Get a new mbuf, and fill in a ICMP header at the bottom |
| 42 | * of the mbuf, followed by the old IP header and 8 bytes |
| 43 | * of its data. |
| 44 | */ |
| 45 | m = m_get(M_DONTWAIT); |
| 46 | if (m == 0) |
| 47 | goto free; |
| 48 | m->m_off = MMAXOFF - (oiplen + 8); |
| 49 | icp->icmp_type = type; |
| 50 | if (type == ICMP_PARAMPROB) { |
| 51 | icp->icmp_code = 0; |
| 52 | icp->icmp_pptr = code; |
| 53 | } else |
| 54 | icp->icmp_code = code; |
| 55 | bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, oiplen + 8); |
| 56 | |
| 57 | /* |
| 58 | * Now prepend an IP header and reflect this packet back to |
| 59 | * the source. |
| 60 | */ |
| 61 | m->m_off -= sizeof (struct ip); |
| 62 | m->m_len += sizeof (struct ip); |
| 63 | nip = (struct ip *)mtod(m, struct ip *); |
| 64 | *nip = *oip; |
| 65 | icmp_reflect(nip); |
| 66 | |
| 67 | free: |
| 68 | /* |
| 69 | * Discard mbufs of original datagram |
| 70 | */ |
| 71 | m_freem(dtom(oip)); |
| 72 | } |
| 73 | |
| 74 | /* |
| 75 | * Process a received ICMP message. |
| 76 | */ |
| 77 | icmp_input(m) |
| 78 | struct mbuf *m; |
| 79 | { |
| 80 | register struct icmp *icp; |
| 81 | register struct ip *ip = mtod(m, struct ip *); |
| 82 | int hlen = ip->ip_hl << 2; |
| 83 | int icmplen = ip->ip_len - hlen; |
| 84 | int i; |
| 85 | extern u_char ip_protox[]; |
| 86 | COUNT(ICMP_INPUT); |
| 87 | |
| 88 | /* |
| 89 | * Locate icmp structure in mbuf, and check |
| 90 | * that not corrupted and of at least minimum length. |
| 91 | */ |
| 92 | m->m_len -= hlen; |
| 93 | m->m_off += hlen; |
| 94 | /* need routine to make sure header is in this mbuf here */ |
| 95 | icp = (struct icmp *)mtod(m, struct icmp *); |
| 96 | i = icp->icmp_cksum; |
| 97 | icp->icmp_cksum = 0; |
| 98 | if (i != in_cksum(m, icmplen) || icmplen < ICMP_MINLEN) |
| 99 | goto free; |
| 100 | |
| 101 | /* |
| 102 | * Message type specific processing. |
| 103 | */ |
| 104 | switch (icp->icmp_type) { |
| 105 | |
| 106 | case ICMP_UNREACH: |
| 107 | case ICMP_TIMXCEED: |
| 108 | case ICMP_PARAMPROB: |
| 109 | case ICMP_SOURCEQUENCH: |
| 110 | case ICMP_REDIRECT: |
| 111 | /* |
| 112 | * Problem with previous datagram; advise |
| 113 | * higher level routines. |
| 114 | */ |
| 115 | if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)) |
| 116 | goto free; |
| 117 | (*protosw[ip_protox[ip->ip_p]].pr_ctlinput)(m); |
| 118 | goto free; |
| 119 | |
| 120 | case ICMP_ECHO: |
| 121 | icp->icmp_type = ICMP_ECHOREPLY; |
| 122 | goto reflect; |
| 123 | |
| 124 | case ICMP_TSTAMP: |
| 125 | if (icmplen < ICMP_TSLEN) |
| 126 | goto free; |
| 127 | icp->icmp_type = ICMP_TSTAMPREPLY; |
| 128 | icp->icmp_rtime = iptime(); |
| 129 | icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ |
| 130 | goto reflect; |
| 131 | |
| 132 | case ICMP_IREQ: |
| 133 | /* fill in source address zero fields! */ |
| 134 | goto reflect; |
| 135 | |
| 136 | case ICMP_ECHOREPLY: |
| 137 | case ICMP_TSTAMPREPLY: |
| 138 | case ICMP_IREQREPLY: |
| 139 | if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)) |
| 140 | goto free; |
| 141 | icmp_gotreply(icp); |
| 142 | goto free; |
| 143 | |
| 144 | default: |
| 145 | goto free; |
| 146 | } |
| 147 | reflect: |
| 148 | icmp_reflect(ip); |
| 149 | free: |
| 150 | m_freem(dtom(ip)); |
| 151 | } |
| 152 | |
| 153 | /* |
| 154 | * Reflect the ip packet back to the source |
| 155 | */ |
| 156 | icmp_reflect(ip) |
| 157 | struct ip *ip; |
| 158 | { |
| 159 | struct in_addr t; |
| 160 | COUNT(ICMP_REFLECT); |
| 161 | |
| 162 | t = ip->ip_src; ip->ip_dst = ip->ip_src; ip->ip_src = t; |
| 163 | /* |
| 164 | * This is a little naive... do we have to munge the options |
| 165 | * to reverse source routing? |
| 166 | */ |
| 167 | icmp_send(ip); |
| 168 | } |
| 169 | |
| 170 | /* |
| 171 | * Send an icmp packet back to the ip level, after |
| 172 | * supplying a checksum. |
| 173 | */ |
| 174 | icmp_send(ip) |
| 175 | struct ip *ip; |
| 176 | { |
| 177 | COUNT(ICMP_SEND); |
| 178 | |
| 179 | m_freem(dtom(ip)); |
| 180 | } |
| 181 | |
| 182 | icmp_ctlinput(m) |
| 183 | struct mbuf *m; |
| 184 | { |
| 185 | COUNT(ICMP_CTLINPUT); |
| 186 | |
| 187 | m_freem(m); |
| 188 | } |
| 189 | |
| 190 | /* |
| 191 | * Got a reply, e.g. to an echo message or a timestamp |
| 192 | * message; nothing is done with these yet. |
| 193 | */ |
| 194 | /*ARGSUSED*/ |
| 195 | icmp_gotreply(icp) |
| 196 | struct icmp *icp; |
| 197 | { |
| 198 | |
| 199 | COUNT(ICMP_GOTREPLY); |
| 200 | } |
| 201 | |
| 202 | icmp_drain() |
| 203 | { |
| 204 | |
| 205 | COUNT(ICMP_DRAIN); |
| 206 | } |
| 207 | |
| 208 | n_time |
| 209 | iptime() |
| 210 | { |
| 211 | int s = spl6(); |
| 212 | u_long t; |
| 213 | |
| 214 | COUNT(IPTIME); |
| 215 | t = (time % SECDAY) * 1000 + lbolt * hz; |
| 216 | splx(s); |
| 217 | return (htonl(t)); |
| 218 | } |