mirror of
https://github.com/sheumann/hush.git
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173 lines
4.4 KiB
C
173 lines
4.4 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Copyright (C) 2011 Denys Vlasenko.
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*
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* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
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#include "common.h"
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#include "d6_common.h"
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#include "dhcpd.h"
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#include <netinet/in.h>
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#include <netinet/if_ether.h>
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#include <netpacket/packet.h>
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#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 2
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void FAST_FUNC d6_dump_packet(struct d6_packet *packet)
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{
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if (dhcp_verbose < 2)
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return;
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bb_info_msg(
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" xid %x"
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, packet->d6_xid32
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);
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//*bin2hex(buf, (void *) packet->chaddr, sizeof(packet->chaddr)) = '\0';
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//bb_info_msg(" chaddr %s", buf);
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}
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#endif
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int FAST_FUNC d6_recv_kernel_packet(struct in6_addr *peer_ipv6
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UNUSED_PARAM
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, struct d6_packet *packet, int fd)
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{
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int bytes;
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memset(packet, 0, sizeof(*packet));
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bytes = safe_read(fd, packet, sizeof(*packet));
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if (bytes < 0) {
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log1("Packet read error, ignoring");
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return bytes; /* returns -1 */
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}
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if (bytes < offsetof(struct d6_packet, d6_options)) {
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bb_info_msg("Packet with bad magic, ignoring");
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return -2;
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}
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log1("Received a packet");
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d6_dump_packet(packet);
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return bytes;
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}
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/* Construct a ipv6+udp header for a packet, send packet */
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int FAST_FUNC d6_send_raw_packet(
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struct d6_packet *d6_pkt, unsigned d6_pkt_size,
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struct in6_addr *src_ipv6, int source_port,
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struct in6_addr *dst_ipv6, int dest_port, const uint8_t *dest_arp,
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int ifindex)
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{
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struct sockaddr_ll dest_sll;
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struct ip6_udp_d6_packet packet;
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int fd;
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int result = -1;
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const char *msg;
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fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IPV6));
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if (fd < 0) {
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msg = "socket(%s)";
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goto ret_msg;
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}
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memset(&dest_sll, 0, sizeof(dest_sll));
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memset(&packet, 0, offsetof(struct ip6_udp_d6_packet, data));
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packet.data = *d6_pkt; /* struct copy */
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dest_sll.sll_family = AF_PACKET;
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dest_sll.sll_protocol = htons(ETH_P_IPV6);
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dest_sll.sll_ifindex = ifindex;
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dest_sll.sll_halen = 6;
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memcpy(dest_sll.sll_addr, dest_arp, 6);
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if (bind(fd, (struct sockaddr *)&dest_sll, sizeof(dest_sll)) < 0) {
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msg = "bind(%s)";
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goto ret_close;
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}
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packet.ip6.ip6_vfc = (6 << 4); /* 4 bits version, top 4 bits of tclass */
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if (src_ipv6)
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packet.ip6.ip6_src = *src_ipv6; /* struct copy */
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packet.ip6.ip6_dst = *dst_ipv6; /* struct copy */
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packet.udp.source = htons(source_port);
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packet.udp.dest = htons(dest_port);
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/* size, excluding IP header: */
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packet.udp.len = htons(sizeof(struct udphdr) + d6_pkt_size);
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packet.ip6.ip6_plen = packet.udp.len;
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/*
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* Someone was smoking weed (at least) while inventing UDP checksumming:
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* UDP checksum skips first four bytes of IPv6 header.
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* 'next header' field should be summed as if it is one more byte
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* to the right, therefore we write its value (IPPROTO_UDP)
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* into ip6_hlim, and its 'real' location remains zero-filled for now.
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*/
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packet.ip6.ip6_hlim = IPPROTO_UDP;
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packet.udp.check = inet_cksum(
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(uint16_t *)&packet + 2,
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offsetof(struct ip6_udp_d6_packet, data) - 4 + d6_pkt_size
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);
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/* fix 'hop limit' and 'next header' after UDP checksumming */
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packet.ip6.ip6_hlim = 1; /* observed Windows machines to use hlim=1 */
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packet.ip6.ip6_nxt = IPPROTO_UDP;
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d6_dump_packet(d6_pkt);
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result = sendto(fd, &packet, offsetof(struct ip6_udp_d6_packet, data) + d6_pkt_size,
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/*flags:*/ 0,
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(struct sockaddr *) &dest_sll, sizeof(dest_sll)
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);
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msg = "sendto";
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ret_close:
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close(fd);
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if (result < 0) {
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ret_msg:
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bb_perror_msg(msg, "PACKET");
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}
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return result;
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}
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/* Let the kernel do all the work for packet generation */
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int FAST_FUNC d6_send_kernel_packet(
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struct d6_packet *d6_pkt, unsigned d6_pkt_size,
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struct in6_addr *src_ipv6, int source_port,
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struct in6_addr *dst_ipv6, int dest_port)
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{
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struct sockaddr_in6 sa;
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int fd;
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int result = -1;
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const char *msg;
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fd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);
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if (fd < 0) {
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msg = "socket(%s)";
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goto ret_msg;
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}
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setsockopt_reuseaddr(fd);
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memset(&sa, 0, sizeof(sa));
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sa.sin6_family = AF_INET6;
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sa.sin6_port = htons(source_port);
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sa.sin6_addr = *src_ipv6; /* struct copy */
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if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
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msg = "bind(%s)";
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goto ret_close;
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}
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memset(&sa, 0, sizeof(sa));
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sa.sin6_family = AF_INET6;
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sa.sin6_port = htons(dest_port);
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sa.sin6_addr = *dst_ipv6; /* struct copy */
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if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
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msg = "connect";
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goto ret_close;
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}
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d6_dump_packet(d6_pkt);
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result = safe_write(fd, d6_pkt, d6_pkt_size);
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msg = "write";
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ret_close:
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close(fd);
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if (result < 0) {
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ret_msg:
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bb_perror_msg(msg, "UDP");
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}
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return result;
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}
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