/* vi: set sw=4 ts=4: */ /* * Copyright (C) 2011 Denys Vlasenko. * * Licensed under GPLv2, see file LICENSE in this source tree. */ #include "common.h" #include "d6_common.h" #include "dhcpc.h" #include "dhcpd.h" #include #include #include #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 2 void FAST_FUNC d6_dump_packet(struct d6_packet *packet) { if (dhcp_verbose < 2) return; bb_info_msg( " xid %x" , packet->d6_xid32 ); //*bin2hex(buf, (void *) packet->chaddr, sizeof(packet->chaddr)) = '\0'; //bb_error_msg(" chaddr %s", buf); } #endif int FAST_FUNC d6_recv_kernel_packet(struct in6_addr *peer_ipv6 UNUSED_PARAM, struct d6_packet *packet, int fd) { int bytes; memset(packet, 0, sizeof(*packet)); bytes = safe_read(fd, packet, sizeof(*packet)); if (bytes < 0) { log1s("packet read error, ignoring"); return bytes; /* returns -1 */ } if (bytes < offsetof(struct d6_packet, d6_options)) { bb_simple_info_msg("packet with bad magic, ignoring"); return -2; } log2("received %s", "a packet"); /* log2 because more informative msg for valid packets is printed later at log1 level */ d6_dump_packet(packet); return bytes; } /* Construct a ipv6+udp header for a packet, send packet */ int FAST_FUNC d6_send_raw_packet_from_client_data_ifindex( struct d6_packet *d6_pkt, unsigned d6_pkt_size, struct in6_addr *src_ipv6, int source_port, struct in6_addr *dst_ipv6, int dest_port, const uint8_t *dest_arp) { struct sockaddr_ll dest_sll; struct ip6_udp_d6_packet packet; int fd; int result = -1; const char *msg; fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IPV6)); if (fd < 0) { msg = "socket(%s)"; goto ret_msg; } memset(&dest_sll, 0, sizeof(dest_sll)); memset(&packet, 0, offsetof(struct ip6_udp_d6_packet, data)); packet.data = *d6_pkt; /* struct copy */ dest_sll.sll_family = AF_PACKET; dest_sll.sll_protocol = htons(ETH_P_IPV6); dest_sll.sll_ifindex = client_data.ifindex; /*dest_sll.sll_hatype = ARPHRD_???;*/ /*dest_sll.sll_pkttype = PACKET_???;*/ dest_sll.sll_halen = 6; memcpy(dest_sll.sll_addr, dest_arp, 6); //TODO: is bind() necessary? we sendto() to this destination, should work anyway if (bind(fd, (struct sockaddr *)&dest_sll, sizeof(dest_sll)) < 0) { msg = "bind(%s)"; goto ret_close; } packet.ip6.ip6_vfc = (6 << 4); /* 4 bits version, top 4 bits of tclass */ // In case we have no IPv6 on our interface at all, we can try // to fill "all hosts" mcast address as source: // /* FF02::1 is Link-local "All_Nodes" address */ // packet.ip6.ip6_dst.s6_addr[0] = 0xff; // packet.ip6.ip6_dst.s6_addr[1] = 0x02; // packet.ip6.ip6_dst.s6_addr[15] = 0x01; // Maybe some servers will be able to respond to us this way? // Users report that leaving ::0 address there makes servers try to reply to ::0, // which doesn't work. if (src_ipv6) packet.ip6.ip6_src = *src_ipv6; /* struct copy */ packet.ip6.ip6_dst = *dst_ipv6; /* struct copy */ packet.udp.source = htons(source_port); packet.udp.dest = htons(dest_port); /* size, excluding IP header: */ packet.udp.len = htons(sizeof(struct udphdr) + d6_pkt_size); packet.ip6.ip6_plen = packet.udp.len; /* * Someone was smoking weed (at least) while inventing UDP checksumming: * UDP checksum skips first four bytes of IPv6 header. * 'next header' field should be summed as if it is one more byte * to the right, therefore we write its value (IPPROTO_UDP) * into ip6_hlim, and its 'real' location remains zero-filled for now. */ packet.ip6.ip6_hlim = IPPROTO_UDP; packet.udp.check = inet_cksum( (uint8_t *)&packet + 4, offsetof(struct ip6_udp_d6_packet, data) - 4 + d6_pkt_size ); /* fix 'hop limit' and 'next header' after UDP checksumming */ packet.ip6.ip6_hlim = 1; /* observed Windows machines to use hlim=1 */ packet.ip6.ip6_nxt = IPPROTO_UDP; d6_dump_packet(d6_pkt); result = sendto(fd, &packet, offsetof(struct ip6_udp_d6_packet, data) + d6_pkt_size, /*flags:*/ 0, (struct sockaddr *) &dest_sll, sizeof(dest_sll) ); msg = "sendto"; ret_close: close(fd); if (result < 0) { ret_msg: bb_perror_msg(msg, "PACKET"); } return result; } /* Let the kernel do all the work for packet generation */ int FAST_FUNC d6_send_kernel_packet_from_client_data_ifindex( struct d6_packet *d6_pkt, unsigned d6_pkt_size, struct in6_addr *src_ipv6, int source_port, struct in6_addr *dst_ipv6, int dest_port) { struct sockaddr_in6 sa; int fd; int result = -1; const char *msg; fd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP); if (fd < 0) { msg = "socket(%s)"; goto ret_msg; } setsockopt_reuseaddr(fd); memset(&sa, 0, sizeof(sa)); sa.sin6_family = AF_INET6; sa.sin6_port = htons(source_port); sa.sin6_addr = *src_ipv6; /* struct copy */ if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) { msg = "bind(%s)"; goto ret_close; } memset(&sa, 0, sizeof(sa)); sa.sin6_family = AF_INET6; sa.sin6_port = htons(dest_port); sa.sin6_addr = *dst_ipv6; /* struct copy */ sa.sin6_scope_id = client_data.ifindex; if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) { msg = "connect"; goto ret_close; } d6_dump_packet(d6_pkt); result = safe_write(fd, d6_pkt, d6_pkt_size); msg = "write"; ret_close: close(fd); if (result < 0) { ret_msg: bb_perror_msg(msg, "UDP"); } return result; }