| 1 | /* ip_icmp.c 4.14 82/04/24 */ |
| 2 | |
| 3 | #include "../h/param.h" |
| 4 | #include "../h/systm.h" |
| 5 | #include "../h/mbuf.h" |
| 6 | #include "../h/protosw.h" |
| 7 | #include "../h/socket.h" |
| 8 | #include "../h/clock.h" |
| 9 | #include "../net/in.h" |
| 10 | #include "../net/in_systm.h" |
| 11 | #include "../net/ip.h" |
| 12 | #include "../net/ip_icmp.h" |
| 13 | |
| 14 | /* |
| 15 | * ICMP routines: error generation, receive packet processing, and |
| 16 | * routines to turnaround packets back to the originator, and |
| 17 | * host table maintenance routines. |
| 18 | */ |
| 19 | |
| 20 | /* |
| 21 | * Generate an error packet of type error |
| 22 | * in response to bad packet ip. |
| 23 | */ |
| 24 | icmp_error(oip, type, code) |
| 25 | struct ip *oip; |
| 26 | int type, code; |
| 27 | { |
| 28 | register unsigned oiplen = oip->ip_hl << 2; |
| 29 | register struct icmp *icp; |
| 30 | struct mbuf *m; |
| 31 | struct ip *nip; |
| 32 | COUNT(ICMP_ERROR); |
| 33 | |
| 34 | /* |
| 35 | * Make sure that the old IP packet had 8 bytes of data to return; |
| 36 | * if not, don't bother. Also don't EVER error if the old |
| 37 | * packet protocol was ICMP. |
| 38 | */ |
| 39 | if (oip->ip_len - oiplen < 8 || oip->ip_p == IPPROTO_ICMP) |
| 40 | goto free; |
| 41 | |
| 42 | /* |
| 43 | * First, formulate icmp message |
| 44 | */ |
| 45 | m = m_get(M_DONTWAIT); |
| 46 | if (m == 0) |
| 47 | goto free; |
| 48 | m->m_len = oiplen + 8 + ICMP_MINLEN; |
| 49 | m->m_off = MMAXOFF - m->m_len; |
| 50 | icp = mtod(m, struct icmp *); |
| 51 | icp->icmp_type = type; |
| 52 | icp->icmp_void = 0; |
| 53 | if (type == ICMP_PARAMPROB) { |
| 54 | icp->icmp_pptr = code; |
| 55 | code = 0; |
| 56 | } |
| 57 | icp->icmp_code = code; |
| 58 | bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, oiplen + 8); |
| 59 | |
| 60 | /* |
| 61 | * Now, copy old ip header in front of icmp |
| 62 | * message. This allows us to reuse any source |
| 63 | * routing info present. |
| 64 | */ |
| 65 | m->m_off -= oiplen; |
| 66 | nip = mtod(m, struct ip *); |
| 67 | bcopy((caddr_t)oip, (caddr_t)nip, oiplen); |
| 68 | nip->ip_len = m->m_len + oiplen; |
| 69 | nip->ip_p = IPPROTO_ICMP; |
| 70 | /* icmp_send adds ip header to m_off and m_len, so we deduct here */ |
| 71 | m->m_off += oiplen; |
| 72 | icmp_reflect(nip); |
| 73 | |
| 74 | free: |
| 75 | m_freem(dtom(oip)); |
| 76 | } |
| 77 | |
| 78 | static char icmpmap[] = { |
| 79 | -1, -1, -1, |
| 80 | PRC_UNREACH_NET, PRC_QUENCH, PRC_REDIRECT_NET, |
| 81 | -1, -1, -1, |
| 82 | -1, -1, PRC_TIMXCEED_INTRANS, |
| 83 | PRC_PARAMPROB, -1, -1, |
| 84 | -1, -1 |
| 85 | }; |
| 86 | |
| 87 | static struct sockproto icmproto = { AF_INET, IPPROTO_ICMP }; |
| 88 | static struct sockaddr_in icmpsrc = { AF_INET }; |
| 89 | static struct sockaddr_in icmpdst = { AF_INET }; |
| 90 | |
| 91 | /* |
| 92 | * Process a received ICMP message. |
| 93 | */ |
| 94 | icmp_input(m) |
| 95 | struct mbuf *m; |
| 96 | { |
| 97 | register struct icmp *icp; |
| 98 | register struct ip *ip = mtod(m, struct ip *); |
| 99 | int icmplen = ip->ip_len, hlen = ip->ip_hl << 2, i; |
| 100 | extern u_char ip_protox[]; |
| 101 | COUNT(ICMP_INPUT); |
| 102 | |
| 103 | /* |
| 104 | * Locate icmp structure in mbuf, and check |
| 105 | * that not corrupted and of at least minimum length. |
| 106 | */ |
| 107 | if (icmplen < ICMP_MINLEN) |
| 108 | goto free; |
| 109 | m->m_len -= hlen; |
| 110 | m->m_off += hlen; |
| 111 | /* need routine to make sure header is in this mbuf here */ |
| 112 | icp = mtod(m, struct icmp *); |
| 113 | i = icp->icmp_cksum; |
| 114 | icp->icmp_cksum = 0; |
| 115 | if (i != in_cksum(m, icmplen)) { |
| 116 | printf("icmp: cksum %x\n", i); |
| 117 | goto free; |
| 118 | } |
| 119 | |
| 120 | /* |
| 121 | * Message type specific processing. |
| 122 | */ |
| 123 | switch (i = icp->icmp_type) { |
| 124 | |
| 125 | case ICMP_UNREACH: |
| 126 | case ICMP_TIMXCEED: |
| 127 | case ICMP_PARAMPROB: |
| 128 | case ICMP_REDIRECT: |
| 129 | case ICMP_SOURCEQUENCH: |
| 130 | /* |
| 131 | * Problem with previous datagram; advise |
| 132 | * higher level routines. |
| 133 | */ |
| 134 | if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)) |
| 135 | goto free; |
| 136 | (*protosw[ip_protox[ip->ip_p]].pr_ctlinput) |
| 137 | (icmpmap[i] + icp->icmp_code, (caddr_t)icp); |
| 138 | goto free; |
| 139 | |
| 140 | case ICMP_ECHO: |
| 141 | icp->icmp_type = ICMP_ECHOREPLY; |
| 142 | goto reflect; |
| 143 | |
| 144 | case ICMP_TSTAMP: |
| 145 | if (icmplen < ICMP_TSLEN) |
| 146 | goto free; |
| 147 | icp->icmp_type = ICMP_TSTAMPREPLY; |
| 148 | icp->icmp_rtime = iptime(); |
| 149 | icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ |
| 150 | goto reflect; |
| 151 | |
| 152 | case ICMP_IREQ: |
| 153 | /* fill in source address zero fields! */ |
| 154 | goto reflect; |
| 155 | |
| 156 | case ICMP_ECHOREPLY: |
| 157 | case ICMP_TSTAMPREPLY: |
| 158 | case ICMP_IREQREPLY: |
| 159 | if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)) |
| 160 | goto free; |
| 161 | icmpsrc.sin_addr = ip->ip_src; |
| 162 | icmpdst.sin_addr = ip->ip_dst; |
| 163 | raw_input(dtom(icp), &icmproto, (struct sockaddr *)&icmpsrc, |
| 164 | (struct sockaddr *)&icmpdst); |
| 165 | goto free; |
| 166 | |
| 167 | default: |
| 168 | goto free; |
| 169 | } |
| 170 | reflect: |
| 171 | icmp_reflect(ip); |
| 172 | free: |
| 173 | m_freem(dtom(ip)); |
| 174 | } |
| 175 | |
| 176 | /* |
| 177 | * Reflect the ip packet back to the source |
| 178 | * TODO: rearrange ip source routing options. |
| 179 | */ |
| 180 | icmp_reflect(ip) |
| 181 | struct ip *ip; |
| 182 | { |
| 183 | struct in_addr t; |
| 184 | COUNT(ICMP_REFLECT); |
| 185 | |
| 186 | t = ip->ip_dst; |
| 187 | ip->ip_dst = ip->ip_src; |
| 188 | ip->ip_src = t; |
| 189 | icmp_send(ip); |
| 190 | } |
| 191 | |
| 192 | int generateicmpmsgs = 0; |
| 193 | |
| 194 | /* |
| 195 | * Send an icmp packet back to the ip level, |
| 196 | * after supplying a checksum. |
| 197 | */ |
| 198 | icmp_send(ip) |
| 199 | struct ip *ip; |
| 200 | { |
| 201 | register int hlen = ip->ip_hl << 2; |
| 202 | register struct icmp *icp; |
| 203 | register struct mbuf *m = dtom(ip); |
| 204 | |
| 205 | COUNT(ICMP_SEND); |
| 206 | if (!generateicmpmsgs) |
| 207 | return; |
| 208 | icp = mtod(m, struct icmp *); |
| 209 | icp->icmp_cksum = 0; |
| 210 | icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); |
| 211 | m->m_off -= hlen; |
| 212 | m->m_len += hlen; |
| 213 | (void) ip_output(m, 0, 0, 0); |
| 214 | } |
| 215 | |
| 216 | n_time |
| 217 | iptime() |
| 218 | { |
| 219 | int s = spl6(); |
| 220 | u_long t; |
| 221 | |
| 222 | COUNT(IPTIME); |
| 223 | t = (time % SECDAY) * 1000 + lbolt * hz; |
| 224 | splx(s); |
| 225 | return (htonl(t)); |
| 226 | } |