From 8b19de666e02f24280728938dd985ecb3673b83e Mon Sep 17 00:00:00 2001 From: Steven Barth Date: Mon, 14 Oct 2013 08:37:38 +0200 Subject: Initial commit --- src/odhcpd.c | 423 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 423 insertions(+) create mode 100644 src/odhcpd.c (limited to 'src/odhcpd.c') diff --git a/src/odhcpd.c b/src/odhcpd.c new file mode 100644 index 0000000..6070bfb --- /dev/null +++ b/src/odhcpd.c @@ -0,0 +1,423 @@ +/** + * Copyright (C) 2012-2013 Steven Barth + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License v2 as published by + * the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include + +#include +#include "odhcpd.h" + + + +static int ioctl_sock; +static int rtnl_socket = -1; +static int rtnl_seq = 0; +static int urandom_fd = -1; + + +int main() +{ + openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON); + uloop_init(); + + if (getuid() != 0) { + syslog(LOG_ERR, "Must be run as root!"); + return 2; + } + + ioctl_sock = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0); + + if ((rtnl_socket = odhcpd_open_rtnl()) < 0) { + syslog(LOG_ERR, "Unable to open socket: %s", strerror(errno)); + return 2; + } + + if ((urandom_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC)) < 0) + return 4; + + signal(SIGUSR1, SIG_IGN); + + if (init_router()) + return 4; + + if (init_dhcpv6()) + return 4; + + if (init_ndp()) + return 4; + + if (init_dhcpv4()) + return 4; + + if (init_ubus()) + return 4; + + odhcpd_run(); + return 0; +} + +int odhcpd_open_rtnl(void) +{ + int sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE); + + // Connect to the kernel netlink interface + struct sockaddr_nl nl = {.nl_family = AF_NETLINK}; + if (connect(sock, (struct sockaddr*)&nl, sizeof(nl))) { + syslog(LOG_ERR, "Failed to connect to kernel rtnetlink: %s", + strerror(errno)); + return -1; + } + + return sock; +} + + +// Read IPv6 MTU for interface +int odhcpd_get_interface_mtu(const char *ifname) +{ + char buf[64]; + const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/mtu"; + snprintf(buf, sizeof(buf), sysctl_pattern, ifname); + + int fd = open(buf, O_RDONLY); + ssize_t len = read(fd, buf, sizeof(buf) - 1); + close(fd); + + if (len < 0) + return -1; + + + buf[len] = 0; + return atoi(buf); + +} + + +// Read IPv6 MAC for interface +int odhcpd_get_mac(const struct interface *iface, uint8_t mac[6]) +{ + struct ifreq ifr; + strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name)); + if (ioctl(ioctl_sock, SIOCGIFHWADDR, &ifr) < 0) + return -1; + memcpy(mac, ifr.ifr_hwaddr.sa_data, 6); + return 0; +} + + +// Forwards a packet on a specific interface +ssize_t odhcpd_send(int socket, struct sockaddr_in6 *dest, + struct iovec *iov, size_t iov_len, + const struct interface *iface) +{ + // Construct headers + uint8_t cmsg_buf[CMSG_SPACE(sizeof(struct in6_pktinfo))] = {0}; + struct msghdr msg = {(void*)dest, sizeof(*dest), iov, iov_len, + cmsg_buf, sizeof(cmsg_buf), 0}; + + // Set control data (define destination interface) + struct cmsghdr *chdr = CMSG_FIRSTHDR(&msg); + chdr->cmsg_level = IPPROTO_IPV6; + chdr->cmsg_type = IPV6_PKTINFO; + chdr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo)); + struct in6_pktinfo *pktinfo = (struct in6_pktinfo*)CMSG_DATA(chdr); + pktinfo->ipi6_ifindex = iface->ifindex; + + // Also set scope ID if link-local + if (IN6_IS_ADDR_LINKLOCAL(&dest->sin6_addr) + || IN6_IS_ADDR_MC_LINKLOCAL(&dest->sin6_addr)) + dest->sin6_scope_id = iface->ifindex; + + // IPV6_PKTINFO doesn't really work for IPv6-raw sockets (bug?) + if (dest->sin6_port == 0) { + msg.msg_control = NULL; + msg.msg_controllen = 0; + } + + char ipbuf[INET6_ADDRSTRLEN]; + inet_ntop(AF_INET6, &dest->sin6_addr, ipbuf, sizeof(ipbuf)); + + ssize_t sent = sendmsg(socket, &msg, MSG_DONTWAIT); + if (sent < 0) + syslog(LOG_WARNING, "Failed to send to %s%%%s (%s)", + ipbuf, iface->ifname, strerror(errno)); + else + syslog(LOG_NOTICE, "Sent %li bytes to %s%%%s", + (long)sent, ipbuf, iface->ifname); + return sent; +} + + +// Detect an IPV6-address currently assigned to the given interface +ssize_t odhcpd_get_interface_addresses(int ifindex, + struct odhcpd_ipaddr *addrs, size_t cnt) +{ + struct { + struct nlmsghdr nhm; + struct ifaddrmsg ifa; + } req = {{sizeof(req), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP, + ++rtnl_seq, 0}, {AF_INET6, 0, 0, 0, ifindex}}; + if (send(rtnl_socket, &req, sizeof(req), 0) < (ssize_t)sizeof(req)) + return 0; + + uint8_t buf[8192]; + ssize_t len = 0, ret = 0; + + for (struct nlmsghdr *nhm = NULL; ; nhm = NLMSG_NEXT(nhm, len)) { + while (len < 0 || !NLMSG_OK(nhm, (size_t)len)) { + len = recv(rtnl_socket, buf, sizeof(buf), 0); + nhm = (struct nlmsghdr*)buf; + if (len < 0 || !NLMSG_OK(nhm, (size_t)len)) { + if (errno == EINTR) + continue; + else + return ret; + } + } + + if (nhm->nlmsg_type != RTM_NEWADDR) + break; + + // Skip address but keep clearing socket buffer + if (ret >= (ssize_t)cnt) + continue; + + struct ifaddrmsg *ifa = NLMSG_DATA(nhm); + if (ifa->ifa_scope != RT_SCOPE_UNIVERSE || + ifa->ifa_index != (unsigned)ifindex) + continue; + + struct rtattr *rta = (struct rtattr*)&ifa[1]; + size_t alen = NLMSG_PAYLOAD(nhm, sizeof(*ifa)); + memset(&addrs[ret], 0, sizeof(addrs[ret])); + addrs[ret].prefix = ifa->ifa_prefixlen; + + while (RTA_OK(rta, alen)) { + if (rta->rta_type == IFA_ADDRESS) { + memcpy(&addrs[ret].addr, RTA_DATA(rta), + sizeof(struct in6_addr)); + } else if (rta->rta_type == IFA_CACHEINFO) { + struct ifa_cacheinfo *ifc = RTA_DATA(rta); + addrs[ret].preferred = ifc->ifa_prefered; + addrs[ret].valid = ifc->ifa_valid; + } + + rta = RTA_NEXT(rta, alen); + } + + if (ifa->ifa_flags & IFA_F_DEPRECATED) + addrs[ret].preferred = 0; + + ++ret; + } + + return ret; +} + + +struct interface* odhcpd_get_interface_by_index(int ifindex) +{ + struct interface *iface; + list_for_each_entry(iface, &interfaces, head) + if (iface->ifindex == ifindex) + return iface; + + return NULL; +} + + +struct interface* odhcpd_get_interface_by_name(const char *name) +{ + struct interface *iface; + list_for_each_entry(iface, &interfaces, head) + if (!strcmp(iface->ifname, name)) + return iface; + + return NULL; +} + + +struct interface* odhcpd_get_master_interface(void) +{ + struct interface *iface; + list_for_each_entry(iface, &interfaces, head) + if (iface->master) + return iface; + + return NULL; +} + + +// Convenience function to receive and do basic validation of packets +static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int events) +{ + struct odhcpd_event *e = container_of(u, struct odhcpd_event, uloop); + + uint8_t data_buf[RELAYD_BUFFER_SIZE], cmsg_buf[128]; + union { + struct sockaddr_in6 in6; + struct sockaddr_in in; + struct sockaddr_ll ll; + struct sockaddr_nl nl; + } addr; + + while (true) { + struct iovec iov = {data_buf, sizeof(data_buf)}; + struct msghdr msg = {&addr, sizeof(addr), &iov, 1, + cmsg_buf, sizeof(cmsg_buf), 0}; + + ssize_t len = recvmsg(u->fd, &msg, MSG_DONTWAIT); + if (len < 0) { + if (errno == EAGAIN) + break; + else + continue; + } + + + // Extract destination interface + int destiface = 0; + int *hlim = NULL; + struct in6_pktinfo *pktinfo; + struct in_pktinfo *pkt4info; + for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL && + destiface == 0; ch = CMSG_NXTHDR(&msg, ch)) { + if (ch->cmsg_level == IPPROTO_IPV6 && + ch->cmsg_type == IPV6_PKTINFO) { + pktinfo = (struct in6_pktinfo*)CMSG_DATA(ch); + destiface = pktinfo->ipi6_ifindex; + } else if (ch->cmsg_level == IPPROTO_IP && + ch->cmsg_type == IP_PKTINFO) { + pkt4info = (struct in_pktinfo*)CMSG_DATA(ch); + destiface = pkt4info->ipi_ifindex; + } else if (ch->cmsg_level == IPPROTO_IPV6 && + ch->cmsg_type == IPV6_HOPLIMIT) { + hlim = (int*)CMSG_DATA(ch); + } + } + + // Check hoplimit if received + if (hlim && *hlim != 255) + continue; + + // Detect interface for packet sockets + if (addr.ll.sll_family == AF_PACKET) + destiface = addr.ll.sll_ifindex; + + struct interface *iface = + odhcpd_get_interface_by_index(destiface); + + if (!iface && addr.nl.nl_family != AF_NETLINK) + continue; + + char ipbuf[INET6_ADDRSTRLEN] = "kernel"; + if (addr.ll.sll_family == AF_PACKET && + len >= (ssize_t)sizeof(struct ip6_hdr)) + inet_ntop(AF_INET6, &data_buf[8], ipbuf, sizeof(ipbuf)); + else if (addr.in6.sin6_family == AF_INET6) + inet_ntop(AF_INET6, &addr.in6.sin6_addr, ipbuf, sizeof(ipbuf)); + else if (addr.in.sin_family == AF_INET) + inet_ntop(AF_INET, &addr.in.sin_addr, ipbuf, sizeof(ipbuf)); + + syslog(LOG_NOTICE, "--"); + syslog(LOG_NOTICE, "Received %li Bytes from %s%%%s", (long)len, + ipbuf, (iface) ? iface->ifname : "netlink"); + + e->handle_dgram(&addr, data_buf, len, iface); + } +} + +// Register events for the multiplexer +int odhcpd_register(struct odhcpd_event *event) +{ + event->uloop.cb = odhcpd_receive_packets; + return uloop_fd_add(&event->uloop, ULOOP_READ); +} + +void odhcpd_urandom(void *data, size_t len) +{ + read(urandom_fd, data, len); +} + + +time_t odhcpd_time(void) +{ + struct timespec ts; + syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &ts); + return ts.tv_sec; +} + + +static const char hexdigits[] = "0123456789abcdef"; +static const int8_t hexvals[] = { + -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, + -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, +}; + +ssize_t odhcpd_unhexlify(uint8_t *dst, size_t len, const char *src) +{ + size_t c; + for (c = 0; c < len && src[0] && src[1]; ++c) { + int8_t x = (int8_t)*src++; + int8_t y = (int8_t)*src++; + if (x < 0 || (x = hexvals[x]) < 0 + || y < 0 || (y = hexvals[y]) < 0) + return -1; + dst[c] = x << 4 | y; + while (((int8_t)*src) < 0 || + (*src && hexvals[(uint8_t)*src] < 0)) + src++; + } + + return c; +} + + +void odhcpd_hexlify(char *dst, const uint8_t *src, size_t len) +{ + for (size_t i = 0; i < len; ++i) { + *dst++ = hexdigits[src[i] >> 4]; + *dst++ = hexdigits[src[i] & 0x0f]; + } + *dst = 0; +} -- cgit v1.2.3