#include #include #include #include #include #include #include #include #include #include #include #include "icmp.h" static char *pr_addr(__u32 addr) { static char buf[4096]; sprintf(buf, "%s", inet_ntoa(*(struct in_addr *)&addr)); return buf; } static void pr_icmph(__u8 type, __u8 code, __u32 info, struct icmphdr *icp) { switch (type) { case ICMP_ECHOREPLY: printf("Echo Reply\n"); /* XXX ID + Seq + Data */ break; case ICMP_DEST_UNREACH: switch(code) { case ICMP_NET_UNREACH: printf("Destination Net Unreachable\n"); break; case ICMP_HOST_UNREACH: printf("Destination Host Unreachable\n"); break; case ICMP_PROT_UNREACH: printf("Destination Protocol Unreachable\n"); break; case ICMP_PORT_UNREACH: printf("Destination Port Unreachable\n"); break; case ICMP_FRAG_NEEDED: printf("Frag needed and DF set (mtu = %u)\n", info); break; case ICMP_SR_FAILED: printf("Source Route Failed\n"); break; case ICMP_PKT_FILTERED: printf("Packet filtered\n"); break; default: printf("Dest Unreachable, Bad Code: %d\n", code); break; } break; case ICMP_SOURCE_QUENCH: printf("Source Quench\n"); break; case ICMP_REDIRECT: switch(code) { case ICMP_REDIR_NET: printf("Redirect Network"); break; case ICMP_REDIR_HOST: printf("Redirect Host"); break; case ICMP_REDIR_NETTOS: printf("Redirect Type of Service and Network"); break; case ICMP_REDIR_HOSTTOS: printf("Redirect Type of Service and Host"); break; default: printf("Redirect, Bad Code: %d", code); break; } if (icp) printf("(New nexthop: %s)\n", pr_addr(icp->un.gateway)); break; case ICMP_ECHO: printf("Echo Request\n"); /* XXX ID + Seq + Data */ break; case ICMP_TIME_EXCEEDED: switch(code) { case ICMP_EXC_TTL: printf("Time to live exceeded\n"); break; case ICMP_EXC_FRAGTIME: printf("Frag reassembly time exceeded\n"); break; default: printf("Time exceeded, Bad Code: %d\n", code); break; } break; case ICMP_PARAMETERPROB: printf("Parameter problem: pointer = %u\n", icp ? (ntohl(icp->un.gateway)>>24) : info); break; case ICMP_TIMESTAMP: printf("Timestamp\n"); /* XXX ID + Seq + 3 timestamps */ break; case ICMP_TIMESTAMPREPLY: printf("Timestamp Reply\n"); /* XXX ID + Seq + 3 timestamps */ break; case ICMP_INFO_REQUEST: printf("Information Request\n"); /* XXX ID + Seq */ break; case ICMP_INFO_REPLY: printf("Information Reply\n"); /* XXX ID + Seq */ break; #ifdef ICMP_MASKREQ case ICMP_MASKREQ: printf("Address Mask Request\n"); break; #endif #ifdef ICMP_MASKREPLY case ICMP_MASKREPLY: printf("Address Mask Reply\n"); break; #endif default: printf("Bad ICMP type: %d\n", type); } } static u_short in_cksum(const u_short *addr, register int len, u_short csum) { const u_short *w = addr; u_short answer; int sum = csum, nleft = len; while (nleft > 1) { sum += *w++; nleft -= 2; } if (nleft == 1) sum += htons(*(u_char *)w << 8); sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */ sum += (sum >> 16); /* add carry */ answer = ~sum; /* truncate to 16 bits */ return answer; } int icmp_parse_reply(__u8 *buf, int len, int seq, struct sockaddr *addr, struct sockaddr *origdest) { struct sockaddr_in *from = (struct sockaddr_in *) addr; struct sockaddr_in *to = (struct sockaddr_in *) origdest; struct icmphdr *icp; struct iphdr *ip; int hlen, csfailed; /* Check the IP header */ ip = (struct iphdr *) buf; hlen = ip->ihl * 4; if (len < hlen + 8 || ip->ihl < 5) return 1; /* Now the ICMP part */ len -= hlen; icp = (struct icmphdr *)(buf + hlen); csfailed = in_cksum((u_short *)icp, len, 0); if (icp->type == ICMP_ECHOREPLY) { if (icp->un.echo.id != getpid() || ntohs(icp->un.echo.sequence) != seq) return 1; /* 'Twas not our ECHO */ printf("From %s: icmp_seq=%u bytes=%d\n", pr_addr(from->sin_addr.s_addr), ntohs(icp->un.echo.sequence), len); } else { /* We fall here when a redirect or source quench arrived. * Also this branch processes icmp errors, when IP_RECVERR * is broken. */ switch (icp->type) { case ICMP_ECHO: /* MUST NOT */ return 1; case ICMP_SOURCE_QUENCH: case ICMP_REDIRECT: case ICMP_DEST_UNREACH: case ICMP_TIME_EXCEEDED: case ICMP_PARAMETERPROB: { struct iphdr * iph = (struct iphdr *)(&icp[1]); struct icmphdr *icp1 = (struct icmphdr*)((unsigned char *)iph + iph->ihl*4); int error_pkt; if (len < 8 + sizeof(struct iphdr) + 8 || len < 8 + iph->ihl * 4 + 8) return 1; if (icp1->type != ICMP_ECHO || iph->daddr != to->sin_addr.s_addr || icp1->un.echo.id != getpid() || ntohs(icp1->un.echo.sequence) != seq) return 1; error_pkt = (icp->type != ICMP_REDIRECT && icp->type != ICMP_SOURCE_QUENCH); if (error_pkt) { //acknowledge(ntohs(icp1->un.echo.sequence)); } printf("From %s: icmp_seq=%u ", pr_addr(from->sin_addr.s_addr), ntohs(icp1->un.echo.sequence)); if (csfailed) printf("(BAD CHECKSUM)"); pr_icmph(icp->type, icp->code, ntohl(icp->un.gateway), icp); return !error_pkt; } default: /* MUST NOT */ break; } printf("From %s: ", pr_addr(from->sin_addr.s_addr)); pr_icmph(icp->type, icp->code, ntohl(icp->un.gateway), icp); return 0; } return 0; } int icmp_send(int fd, struct sockaddr *to, int tolen, void *buf, int buflen) { int i; i = sendto(fd, buf, buflen, 0, to, tolen); if (i != buflen) return -1; return 0; } int icmp_send_frag_needed(int fd, struct sockaddr *to, int tolen, struct iphdr *iph, int newmtu) { struct sockaddr_in *to_in = (struct sockaddr_in *) to; const int len = sizeof(struct icmphdr) + sizeof(struct iphdr) + 8; char packet[len]; struct icmphdr *icp; icp = (struct icmphdr *) packet; icp->type = ICMP_DEST_UNREACH; icp->code = ICMP_FRAG_NEEDED; icp->checksum = 0; icp->un.frag.__unused = 0; icp->un.frag.mtu = htons(newmtu); /* copy ip header + 64-bits of original packet */ memcpy(icp + 1, iph, sizeof(struct iphdr) + 8); icp->checksum = in_cksum((u_short *) icp, len, 0); printf("To %s: frag_needed mtu=%d\n", pr_addr(to_in->sin_addr.s_addr), newmtu); return icmp_send(fd, to, tolen, packet, len); } int icmp_send_ping(int fd, struct sockaddr *to, int tolen, int seq, int total_size) { struct sockaddr_in *to_in = (struct sockaddr_in *) to; __u8 packet[1500]; struct icmphdr *icp; int len; if (total_size > sizeof(packet)) return -1; if (total_size < sizeof(struct iphdr) + sizeof(struct icmphdr)) total_size = sizeof(struct iphdr) + sizeof(struct icmphdr); len = total_size - sizeof(struct iphdr); memset(packet, 0, sizeof(packet)); icp = (struct icmphdr *) packet; icp->type = ICMP_ECHO; icp->code = 0; icp->checksum = 0; icp->un.echo.sequence = htons(seq); icp->un.echo.id = getpid(); icp->checksum = in_cksum((u_short *) icp, len, 0); #if 0 printf("To %s: icmp_seq=%u bytes=%d\n", pr_addr(to_in->sin_addr.s_addr), seq, len); #endif return icmp_send(fd, to, tolen, (void *) packet, len); } int icmp_read_reply(int fd, struct sockaddr *from, socklen_t fromlen, __u8 *buf, int buflen) { int len; len = recvfrom(fd, buf, buflen, 0, from, &fromlen); if (len < 0) { if (errno == EAGAIN || errno == EINTR) return 0; return -1; } return len; } int icmp_open(float timeout) { const int pmtudisc = IP_PMTUDISC_DO; struct timeval tv; int fd; fd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); if (fd < 0) { perror("mtuinject: socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)"); goto err; } if (setsockopt(fd, SOL_IP, IP_MTU_DISCOVER, &pmtudisc, sizeof(pmtudisc)) == -1) { perror("ping: IP_MTU_DISCOVER"); goto err_close; } tv.tv_sec = (time_t) timeout; tv.tv_usec = (timeout - tv.tv_sec) * 1000000; setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, (char*)&tv, sizeof(tv)); tv.tv_sec = (time_t) timeout; tv.tv_usec = (timeout - tv.tv_sec) * 1000000; if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, (char*)&tv, sizeof(tv)) == -1) goto err_close; return fd; err_close: close(fd); err: return -1; } void icmp_close(int fd) { close(fd); }