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s20161105
rarpd.c
725 строк
15 KB
David Heidelberger
replace non-POSIX compilant caddr_t with char *
18 апр 2014, 16:23
18 апр 2014, 16:23
cce92c8
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/* * rarpd.c RARP daemon. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> */ #include <stdio.h> #include <syslog.h> #include <dirent.h> #include <malloc.h> #include <string.h> #include <unistd.h> #include <stdlib.h> #include <netdb.h> #include <errno.h> #include <fcntl.h> #include <signal.h> #include <poll.h> #include <arpa/inet.h> #include <netinet/in.h> #include <linux/if.h> #include <linux/if_arp.h> #include <linux/if_packet.h> #include <linux/filter.h> #include <sys/ioctl.h> #include <sys/socket.h> int do_reload = 1; int debug; int verbose; int ifidx; int allow_offlink; int only_ethers; int all_ifaces; int listen_arp; char *ifname; char *tftp_dir = "/etc/tftpboot"; extern int ether_ntohost(char *name, unsigned char *ea); void usage(void) __attribute__((noreturn)); struct iflink { struct iflink *next; int index; int hatype; unsigned char lladdr[16]; char name[IFNAMSIZ]; struct ifaddr *ifa_list; } *ifl_list; struct ifaddr { struct ifaddr *next; __u32 prefix; __u32 mask; __u32 local; }; struct rarp_map { struct rarp_map *next; int ifindex; int arp_type; int lladdr_len; unsigned char lladdr[16]; __u32 ipaddr; } *rarp_db; void usage() { fprintf(stderr, "Usage: rarpd [ -dveaA ] [ -b tftpdir ] [ interface]\n"); exit(1); } void load_db(void) { } void load_if(void) { int fd; struct ifreq *ifrp, *ifend; struct iflink *ifl; struct ifaddr *ifa; struct ifconf ifc; struct ifreq ibuf[256]; if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { syslog(LOG_ERR, "socket: %m"); return; } ifc.ifc_len = sizeof ibuf; ifc.ifc_buf = (char *)ibuf; if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 || ifc.ifc_len < (int)sizeof(struct ifreq)) { syslog(LOG_ERR, "SIOCGIFCONF: %m"); close(fd); return; } while ((ifl = ifl_list) != NULL) { while ((ifa = ifl->ifa_list) != NULL) { ifl->ifa_list = ifa->next; free(ifa); } ifl_list = ifl->next; free(ifl); } ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len); for (ifrp = ibuf; ifrp < ifend; ifrp++) { __u32 addr; __u32 mask; __u32 prefix; if (ifrp->ifr_addr.sa_family != AF_INET) continue; addr = ((struct sockaddr_in*)&ifrp->ifr_addr)->sin_addr.s_addr; if (addr == 0) continue; if (ioctl(fd, SIOCGIFINDEX, ifrp)) { syslog(LOG_ERR, "ioctl(SIOCGIFNAME): %m"); continue; } if (ifidx && ifrp->ifr_ifindex != ifidx) continue; for (ifl = ifl_list; ifl; ifl = ifl->next) if (ifl->index == ifrp->ifr_ifindex) break; if (ifl == NULL) { char *p; int index = ifrp->ifr_ifindex; if (ioctl(fd, SIOCGIFHWADDR, ifrp)) { syslog(LOG_ERR, "ioctl(SIOCGIFHWADDR): %m"); continue; } ifl = (struct iflink*)malloc(sizeof(*ifl)); if (ifl == NULL) continue; memset(ifl, 0, sizeof(*ifl)); ifl->next = ifl_list; ifl_list = ifl; ifl->index = index; ifl->hatype = ifrp->ifr_hwaddr.sa_family; memcpy(ifl->lladdr, ifrp->ifr_hwaddr.sa_data, 14); strncpy(ifl->name, ifrp->ifr_name, IFNAMSIZ); p = strchr(ifl->name, ':'); if (p) *p = 0; if (verbose) syslog(LOG_INFO, "link %s", ifl->name); } if (ioctl(fd, SIOCGIFNETMASK, ifrp)) { syslog(LOG_ERR, "ioctl(SIOCGIFMASK): %m"); continue; } mask = ((struct sockaddr_in*)&ifrp->ifr_netmask)->sin_addr.s_addr; if (ioctl(fd, SIOCGIFDSTADDR, ifrp)) { syslog(LOG_ERR, "ioctl(SIOCGIFDSTADDR): %m"); continue; } prefix = ((struct sockaddr_in*)&ifrp->ifr_dstaddr)->sin_addr.s_addr; for (ifa = ifl->ifa_list; ifa; ifa = ifa->next) { if (ifa->local == addr && ifa->prefix == prefix && ifa->mask == mask) break; } if (ifa == NULL) { if (mask == 0 || prefix == 0) continue; ifa = (struct ifaddr*)malloc(sizeof(*ifa)); memset(ifa, 0, sizeof(*ifa)); ifa->local = addr; ifa->prefix = prefix; ifa->mask = mask; ifa->next = ifl->ifa_list; ifl->ifa_list = ifa; if (verbose) { int i; __u32 m = ~0U; for (i=32; i>=0; i--) { if (htonl(m) == mask) break; m <<= 1; } if (addr == prefix) { syslog(LOG_INFO, " addr %s/%d on %s\n", inet_ntoa(*(struct in_addr*)&addr), i, ifl->name); } else { char tmpa[64]; sprintf(tmpa, "%s", inet_ntoa(*(struct in_addr*)&addr)); syslog(LOG_INFO, " addr %s %s/%d on %s\n", tmpa, inet_ntoa(*(struct in_addr*)&prefix), i, ifl->name); } } } } } void configure(void) { load_if(); load_db(); } int bootable(__u32 addr) { struct dirent *dent; DIR *d; char name[9]; sprintf(name, "%08X", (__u32)ntohl(addr)); d = opendir(tftp_dir); if (d == NULL) { syslog(LOG_ERR, "opendir: %m"); return 0; } while ((dent = readdir(d)) != NULL) { if (strncmp(dent->d_name, name, 8) == 0) break; } closedir(d); return dent != NULL; } struct ifaddr *select_ipaddr(int ifindex, __u32 *sel_addr, __u32 **alist) { struct iflink *ifl; struct ifaddr *ifa; int retry = 0; int i; retry: for (ifl=ifl_list; ifl; ifl=ifl->next) if (ifl->index == ifindex) break; if (ifl == NULL && !retry) { retry++; load_if(); goto retry; } if (ifl == NULL) return NULL; for (i=0; alist[i]; i++) { __u32 addr = *(alist[i]); for (ifa=ifl->ifa_list; ifa; ifa=ifa->next) { if (!((ifa->prefix^addr)&ifa->mask)) { *sel_addr = addr; return ifa; } } if (ifa == NULL && retry==0) { retry++; load_if(); goto retry; } } if (i==1 && allow_offlink) { *sel_addr = *(alist[0]); return ifl->ifa_list; } syslog(LOG_ERR, "Off-link request on %s", ifl->name); return NULL; } struct rarp_map *rarp_lookup(int ifindex, int hatype, int halen, unsigned char *lladdr) { struct rarp_map *r; for (r=rarp_db; r; r=r->next) { if (r->arp_type != hatype && r->arp_type != -1) continue; if (r->lladdr_len != halen) continue; if (r->ifindex != ifindex && r->ifindex != 0) continue; if (memcmp(r->lladdr, lladdr, halen) == 0) break; } if (r == NULL) { if (hatype == ARPHRD_ETHER && halen == 6) { struct ifaddr *ifa; struct hostent *hp; char ename[256]; static struct rarp_map emap = { NULL, 0, ARPHRD_ETHER, 6, }; if (ether_ntohost(ename, lladdr) != 0 || (hp = gethostbyname(ename)) == NULL) { if (verbose) syslog(LOG_INFO, "not found in /etc/ethers"); return NULL; } if (hp->h_addrtype != AF_INET) { syslog(LOG_ERR, "no IP address"); return NULL; } ifa = select_ipaddr(ifindex, &emap.ipaddr, (__u32 **)hp->h_addr_list); if (ifa) { memcpy(emap.lladdr, lladdr, 6); if (only_ethers || bootable(emap.ipaddr)) return &emap; if (verbose) syslog(LOG_INFO, "not bootable"); } } } return r; } static int load_arp_bpflet(int fd) { static struct sock_filter insns[] = { BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6), BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, ARPOP_RREQUEST, 0, 1), BPF_STMT(BPF_RET|BPF_K, 1024), BPF_STMT(BPF_RET|BPF_K, 0), }; static struct sock_fprog filter = { sizeof insns / sizeof(insns[0]), insns }; return setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)); } int put_mylladdr(unsigned char **ptr_p, int ifindex, int alen) { struct iflink *ifl; for (ifl=ifl_list; ifl; ifl = ifl->next) if (ifl->index == ifindex) break; if (ifl==NULL) return -1; memcpy(*ptr_p, ifl->lladdr, alen); *ptr_p += alen; return 0; } int put_myipaddr(unsigned char **ptr_p, int ifindex, __u32 hisipaddr) { __u32 laddr = 0; struct iflink *ifl; struct ifaddr *ifa; for (ifl=ifl_list; ifl; ifl = ifl->next) if (ifl->index == ifindex) break; if (ifl==NULL) return -1; for (ifa=ifl->ifa_list; ifa; ifa=ifa->next) { if (!((ifa->prefix^hisipaddr)&ifa->mask)) { laddr = ifa->local; break; } } memcpy(*ptr_p, &laddr, 4); *ptr_p += 4; return 0; } void arp_advise(int ifindex, unsigned char *lladdr, int lllen, __u32 ipaddr) { int fd; struct arpreq req; struct sockaddr_in *sin; struct iflink *ifl; for (ifl=ifl_list; ifl; ifl = ifl->next) if (ifl->index == ifindex) break; if (ifl == NULL) return; fd = socket(AF_INET, SOCK_DGRAM, 0); memset(&req, 0, sizeof(req)); req.arp_flags = ATF_COM; sin = (struct sockaddr_in *)&req.arp_pa; sin->sin_family = AF_INET; sin->sin_addr.s_addr = ipaddr; req.arp_ha.sa_family = ifl->hatype; memcpy(req.arp_ha.sa_data, lladdr, lllen); memcpy(req.arp_dev, ifl->name, IFNAMSIZ); if (ioctl(fd, SIOCSARP, &req)) syslog(LOG_ERR, "SIOCSARP: %m"); close(fd); } void serve_it(int fd) { unsigned char buf[1024]; struct sockaddr_ll sll; socklen_t sll_len = sizeof(sll); struct arphdr *a = (struct arphdr*)buf; struct rarp_map *rmap; unsigned char *ptr; int n; n = recvfrom(fd, buf, sizeof(buf), MSG_DONTWAIT, (struct sockaddr*)&sll, &sll_len); if (n<0) { if (errno != EINTR && errno != EAGAIN) syslog(LOG_ERR, "recvfrom: %m"); return; } /* Do not accept packets for other hosts and our own ones */ if (sll.sll_pkttype != PACKET_BROADCAST && sll.sll_pkttype != PACKET_MULTICAST && sll.sll_pkttype != PACKET_HOST) return; if (ifidx && sll.sll_ifindex != ifidx) return; if (n<sizeof(*a)) { syslog(LOG_ERR, "truncated arp packet; len=%d", n); return; } /* Accept only RARP requests */ if (a->ar_op != htons(ARPOP_RREQUEST)) return; if (verbose) { int i; char tmpbuf[16*3]; char *ptr = tmpbuf; for (i=0; i<sll.sll_halen; i++) { if (i) { sprintf(ptr, ":%02x", sll.sll_addr[i]); ptr++; } else sprintf(ptr, "%02x", sll.sll_addr[i]); ptr += 2; } syslog(LOG_INFO, "RARP request from %s on if%d", tmpbuf, sll.sll_ifindex); } /* Sanity checks */ /* 1. IP only -> pln==4 */ if (a->ar_pln != 4) { syslog(LOG_ERR, "interesting rarp_req plen=%d", a->ar_pln); return; } /* 2. ARP protocol must be IP */ if (a->ar_pro != htons(ETH_P_IP)) { syslog(LOG_ERR, "rarp protocol is not IP %04x", ntohs(a->ar_pro)); return; } /* 3. ARP types must match */ if (htons(sll.sll_hatype) != a->ar_hrd) { switch (sll.sll_hatype) { case ARPHRD_FDDI: if (a->ar_hrd == htons(ARPHRD_ETHER) || a->ar_hrd == htons(ARPHRD_IEEE802)) break; default: syslog(LOG_ERR, "rarp htype mismatch"); return; } } /* 3. LL address lengths must be equal */ if (a->ar_hln != sll.sll_halen) { syslog(LOG_ERR, "rarp hlen mismatch"); return; } /* 4. Check packet length */ if (sizeof(*a) + 2*4 + 2*a->ar_hln > n) { syslog(LOG_ERR, "truncated rarp request; len=%d", n); return; } /* 5. Silly check: if this guy set different source addresses in MAC header and in ARP, he is insane */ if (memcmp(sll.sll_addr, a+1, sll.sll_halen)) { syslog(LOG_ERR, "this guy set different his lladdrs in arp and header"); return; } /* End of sanity checks */ /* Lookup requested target in our database */ rmap = rarp_lookup(sll.sll_ifindex, sll.sll_hatype, sll.sll_halen, (unsigned char*)(a+1) + sll.sll_halen + 4); if (rmap == NULL) return; /* Prepare reply. It is almost ready, we only replace ARP packet type, put our lladdr and IP address to source fileds, and fill target IP address. */ a->ar_op = htons(ARPOP_RREPLY); ptr = (unsigned char*)(a+1); if (put_mylladdr(&ptr, sll.sll_ifindex, rmap->lladdr_len)) return; if (put_myipaddr(&ptr, sll.sll_ifindex, rmap->ipaddr)) return; /* It is already filled */ ptr += rmap->lladdr_len; memcpy(ptr, &rmap->ipaddr, 4); ptr += 4; /* Update our ARP cache. Probably, this guy will not able to make ARP (if it is broken) */ arp_advise(sll.sll_ifindex, rmap->lladdr, rmap->lladdr_len, rmap->ipaddr); /* Sendto is blocking, but with 5sec timeout */ alarm(5); sendto(fd, buf, ptr - buf, 0, (struct sockaddr*)&sll, sizeof(sll)); alarm(0); } void catch_signal(int sig, void (*handler)(int)) { struct sigaction sa; memset(&sa, 0, sizeof(sa)); sa.sa_handler = handler; #ifdef SA_INTERRUPT sa.sa_flags = SA_INTERRUPT; #endif sigaction(sig, &sa, NULL); } void sig_alarm(int signo) { } void sig_hup(int signo) { do_reload = 1; } int main(int argc, char **argv) { struct pollfd pset[2]; int psize; int opt; opterr = 0; while ((opt = getopt(argc, argv, "aAb:dvoe")) != EOF) { switch (opt) { case 'a': ++all_ifaces; break; case 'A': ++listen_arp; break; case 'd': ++debug; break; case 'v': ++verbose; break; case 'o': ++allow_offlink; break; case 'e': ++only_ethers; break; case 'b': tftp_dir = optarg; break; default: usage(); } } if (argc > optind) { if (argc > optind+1) usage(); ifname = argv[optind]; } psize = 1; pset[0].fd = socket(PF_PACKET, SOCK_DGRAM, 0); if (ifname) { struct ifreq ifr; memset(&ifr, 0, sizeof(ifr)); strncpy(ifr.ifr_name, ifname, IFNAMSIZ); if (ioctl(pset[0].fd, SIOCGIFINDEX, &ifr)) { perror("ioctl(SIOCGIFINDEX)"); usage(); } ifidx = ifr.ifr_ifindex; } pset[1].fd = -1; if (listen_arp) { pset[1].fd = socket(PF_PACKET, SOCK_DGRAM, 0); if (pset[1].fd >= 0) { load_arp_bpflet(pset[1].fd); psize = 1; } } if (pset[1].fd >= 0) { struct sockaddr_ll sll; memset(&sll, 0, sizeof(sll)); sll.sll_family = AF_PACKET; sll.sll_protocol = htons(ETH_P_ARP); sll.sll_ifindex = all_ifaces ? 0 : ifidx; if (bind(pset[1].fd, (struct sockaddr*)&sll, sizeof(sll)) < 0) { close(pset[1].fd); pset[1].fd = -1; psize = 1; } } if (pset[0].fd >= 0) { struct sockaddr_ll sll; memset(&sll, 0, sizeof(sll)); sll.sll_family = AF_PACKET; sll.sll_protocol = htons(ETH_P_RARP); sll.sll_ifindex = all_ifaces ? 0 : ifidx; if (bind(pset[0].fd, (struct sockaddr*)&sll, sizeof(sll)) < 0) { close(pset[0].fd); pset[0].fd = -1; } } if (pset[0].fd < 0) { pset[0] = pset[1]; psize--; } if (psize == 0) { fprintf(stderr, "failed to bind any socket. Aborting.\n"); exit(1); } if (!debug) { int fd; pid_t pid = fork(); if (pid > 0) exit(0); else if (pid == -1) { perror("rarpd: fork"); exit(1); } if (chdir("/") < 0) { perror("rarpd: chdir"); exit(1); } fd = open("/dev/null", O_RDWR); if (fd >= 0) { dup2(fd, 0); dup2(fd, 1); dup2(fd, 2); if (fd > 2) close(fd); } setsid(); } openlog("rarpd", LOG_PID | LOG_CONS, LOG_DAEMON); catch_signal(SIGALRM, sig_alarm); catch_signal(SIGHUP, sig_hup); for (;;) { int i; if (do_reload) { configure(); do_reload = 0; } #define EVENTS (POLLIN|POLLPRI|POLLERR|POLLHUP) pset[0].events = EVENTS; pset[0].revents = 0; pset[1].events = EVENTS; pset[1].revents = 0; i = poll(pset, psize, -1); if (i <= 0) { if (errno != EINTR && i<0) { syslog(LOG_ERR, "poll returned some crap: %m\n"); sleep(10); } continue; } for (i=0; i<psize; i++) { if (pset[i].revents&EVENTS) serve_it(pset[i].fd); } } }