/* dnsmasq is Copyright (c) 2000-2006 Simon Kelley 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; version 2 dated June, 1991. 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 "dnsmasq.h" #ifdef HAVE_LINUX_NETWORK #include #include #include /* linux 2.6.19 buggers up the headers, patch it up here. */ #ifndef IFA_RTA # define IFA_RTA(r) \ ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ifaddrmsg)))) # include #endif static struct iovec iov; static void nl_err(struct nlmsghdr *h); static void nl_routechange(struct nlmsghdr *h); void netlink_init(void) { struct sockaddr_nl addr; addr.nl_family = AF_NETLINK; addr.nl_pad = 0; addr.nl_pid = 0; /* autobind */ #ifdef HAVE_IPV6 addr.nl_groups = RTMGRP_IPV4_ROUTE | RTMGRP_IPV6_ROUTE; #else addr.nl_groups = RTMGRP_IPV4_ROUTE; #endif /* May not be able to have permission to set multicast groups don't die in that case */ if ((daemon->netlinkfd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE)) != -1) { if (bind(daemon->netlinkfd, (struct sockaddr *)&addr, sizeof(addr)) == -1) { addr.nl_groups = 0; if (errno != EPERM || bind(daemon->netlinkfd, (struct sockaddr *)&addr, sizeof(addr)) == -1) daemon->netlinkfd = -1; } } if (daemon->netlinkfd == -1) die(_("cannot create netlink socket: %s"), NULL, EC_MISC); iov.iov_len = 200; iov.iov_base = safe_malloc(iov.iov_len); } static ssize_t netlink_recv(void) { struct msghdr msg; ssize_t rc; msg.msg_control = NULL; msg.msg_controllen = 0; msg.msg_name = NULL; msg.msg_namelen = 0; msg.msg_iov = &iov; msg.msg_iovlen = 1; while (1) { msg.msg_flags = 0; while ((rc = recvmsg(daemon->netlinkfd, &msg, MSG_PEEK)) == -1 && errno == EINTR); /* 2.2.x doesn't suport MSG_PEEK at all, returning EOPNOTSUPP, so we just grab a big buffer and pray in that case. */ if (rc == -1 && errno == EOPNOTSUPP) { if (!expand_buf(&iov, 2000)) return -1; break; } if (rc == -1 || !(msg.msg_flags & MSG_TRUNC)) break; if (!expand_buf(&iov, iov.iov_len + 100)) return -1; } /* finally, read it for real */ while ((rc = recvmsg(daemon->netlinkfd, &msg, 0)) == -1 && errno == EINTR); return rc; } int iface_enumerate(void *parm, int (*ipv4_callback)(), int (*ipv6_callback)()) { struct sockaddr_nl addr; struct nlmsghdr *h; ssize_t len; static unsigned int seq = 0; int family = AF_INET; struct { struct nlmsghdr nlh; struct rtgenmsg g; } req; addr.nl_family = AF_NETLINK; addr.nl_pad = 0; addr.nl_groups = 0; addr.nl_pid = 0; /* address to kernel */ again: req.nlh.nlmsg_len = sizeof(req); req.nlh.nlmsg_type = RTM_GETADDR; req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST | NLM_F_ACK; req.nlh.nlmsg_pid = 0; req.nlh.nlmsg_seq = ++seq; req.g.rtgen_family = family; /* Don't block in recvfrom if send fails */ while((len = sendto(daemon->netlinkfd, (void *)&req, sizeof(req), 0, (struct sockaddr *)&addr, sizeof(addr))) == -1 && retry_send()); if (len == -1) return 0; while (1) { if ((len = netlink_recv()) == -1) return 0; for (h = (struct nlmsghdr *)iov.iov_base; NLMSG_OK(h, (size_t)len); h = NLMSG_NEXT(h, len)) if (h->nlmsg_type == NLMSG_ERROR) nl_err(h); else if (h->nlmsg_seq != seq) nl_routechange(h); /* May be multicast arriving async */ else if (h->nlmsg_type == NLMSG_DONE) { #ifdef HAVE_IPV6 if (family == AF_INET && ipv6_callback) { family = AF_INET6; goto again; } #endif return 1; } else if (h->nlmsg_type == RTM_NEWADDR) { struct ifaddrmsg *ifa = NLMSG_DATA(h); struct rtattr *rta = IFA_RTA(ifa); unsigned int len1 = h->nlmsg_len - NLMSG_LENGTH(sizeof(*ifa)); if (ifa->ifa_family == AF_INET) { struct in_addr netmask, addr, broadcast; netmask.s_addr = htonl(0xffffffff << (32 - ifa->ifa_prefixlen)); addr.s_addr = 0; broadcast.s_addr = 0; while (RTA_OK(rta, len1)) { if (rta->rta_type == IFA_LOCAL) addr = *((struct in_addr *)(rta+1)); else if (rta->rta_type == IFA_BROADCAST) broadcast = *((struct in_addr *)(rta+1)); rta = RTA_NEXT(rta, len1); } if (addr.s_addr && ipv4_callback) if (!((*ipv4_callback)(addr, ifa->ifa_index, netmask, broadcast, parm))) return 0; } #ifdef HAVE_IPV6 else if (ifa->ifa_family == AF_INET6) { struct in6_addr *addrp = NULL; while (RTA_OK(rta, len1)) { if (rta->rta_type == IFA_ADDRESS) addrp = ((struct in6_addr *)(rta+1)); rta = RTA_NEXT(rta, len1); } if (addrp && ipv6_callback) if (!((*ipv6_callback)(addrp, ifa->ifa_index, ifa->ifa_index, parm))) return 0; } #endif } } } void netlink_multicast(void) { ssize_t len; struct nlmsghdr *h; if ((len = netlink_recv()) != -1) { for (h = (struct nlmsghdr *)iov.iov_base; NLMSG_OK(h, (size_t)len); h = NLMSG_NEXT(h, len)) if (h->nlmsg_type == NLMSG_ERROR) nl_err(h); else nl_routechange(h); } } static void nl_err(struct nlmsghdr *h) { struct nlmsgerr *err = NLMSG_DATA(h); if (err->error != 0) my_syslog(LOG_ERR, _("netlink returns error: %s"), strerror(-(err->error))); } /* We arrange to receive netlink multicast messages whenever the network route is added. If this happens and we still have a DNS packet in the buffer, we re-send it. This helps on DoD links, where frequently the packet which triggers dialling is a DNS query, which then gets lost. By re-sending, we can avoid the lookup failing. */ static void nl_routechange(struct nlmsghdr *h) { if (h->nlmsg_type == RTM_NEWROUTE && daemon->srv_save) { struct rtmsg *rtm = NLMSG_DATA(h); if (rtm->rtm_type == RTN_UNICAST && rtm->rtm_scope == RT_SCOPE_LINK) while(sendto(daemon->srv_save->sfd->fd, daemon->packet, daemon->packet_len, 0, &daemon->srv_save->addr.sa, sa_len(&daemon->srv_save->addr)) == -1 && retry_send()); } } #endif