forked from aholler/snetmanmon
/
send_rpc_ra.cpp
204 lines (173 loc) · 5.45 KB
/
send_rpc_ra.cpp
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// send_rpc_ra
//
// (C) 2015 Alexander Holler
//
#include <cstring>
#include <iostream>
#include <netinet/icmp6.h>
#include <sys/socket.h>
#include <unistd.h> // close
#include <net/if.h> // if_nametoindex
#include <errno.h>
#include <ifaddrs.h>
#include <arpa/inet.h> // inet_pton
static bool is_link_local(const in6_addr& addr)
{
static const in6_addr addr6_linklocal = { { {
0xfe, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
} } };
return !(std::memcmp(&addr6_linklocal, &addr, 8));
}
static int set_src_addr(const std::string& if_name, in6_addr& src)
{
ifaddrs* ifaddr;
if (::getifaddrs(&ifaddr) == -1) {
std::cerr << "Error from getifaddrs ( " << strerror(errno) << ")!\n";
return 1;
}
int rc = 2;
for (ifaddrs* ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
if (ifa->ifa_addr == NULL)
continue;
if (ifa->ifa_addr->sa_family != AF_INET6)
continue;
if (!ifa->ifa_name)
continue;
if (if_name == ifa->ifa_name) {
if (!is_link_local(reinterpret_cast<const sockaddr_in6*>(ifa->ifa_addr)->sin6_addr))
continue;
src = reinterpret_cast<const sockaddr_in6*>(ifa->ifa_addr)->sin6_addr;
rc = 0;
break;
}
}
::freeifaddrs(ifaddr);
return rc;
}
static int check_prefix(const std::string if_name, const in6_addr& prefix)
{
ifaddrs* ifaddr;
if (::getifaddrs(&ifaddr) == -1) {
std::cerr << "Error from getifaddrs ( " << strerror(errno) << ")!\n";
return 1;
}
for (ifaddrs* ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
if (ifa->ifa_addr == NULL)
continue;
if (ifa->ifa_addr->sa_family != AF_INET6)
continue;
if (!ifa->ifa_name)
continue;
if (if_name == ifa->ifa_name) {
if (!std::memcmp(&prefix, &reinterpret_cast<const sockaddr_in6*>(ifa->ifa_addr)->sin6_addr, 8)) {
::freeifaddrs(ifaddr);
return 2;
}
}
}
::freeifaddrs(ifaddr);
return 0;
}
int main(int argc, char** argv)
{
std::cout << "\nsend_rpc_ra\n";
std::cout << "\n(C) 2015 Alexander Holler\n\n";
if (argc != 4) {
std::cout << "Usage: " <<
"send_rpc_ra interface destination_ipv6 prefix_ipv6\n" <<
"Example: " <<
"send_ra eth0 ff02::1 fecd::\n\n";
return 1;
}
std::string interface(argv[1]);
std::string destination(argv[2]);
std::string prefix(argv[3]);
struct {
nd_router_advert nra;
nd_opt_prefix_info opt_prefix_info;
} my_ra;
std::memset(&my_ra, 0, sizeof(my_ra));
my_ra.nra.nd_ra_type = ND_ROUTER_ADVERT;
msghdr msghdr;
std::memset(&msghdr, 0, sizeof(msghdr));
// destination address
sockaddr_in6 dst;
std::memset(&dst, 0, sizeof(dst));
dst.sin6_family = AF_INET6;
dst.sin6_port = htons(IPPROTO_ICMPV6);
if (inet_pton(AF_INET6, destination.c_str(), &dst.sin6_addr) != 1) {
std::cerr << "Error setting destination '" << destination << "'\n";
return 2;
}
msghdr.msg_name = &dst;
msghdr.msg_namelen = sizeof(dst);
iovec iov[2];
std::memset(&iov, 0, sizeof(iov));
iov[0].iov_base = &my_ra;
iov[0].iov_len = sizeof(my_ra);
msghdr.msg_iov = (struct iovec *) &iov;
msghdr.msg_iovlen = sizeof(iov) / sizeof(struct iovec);
in6_pktinfo* ipi;
cmsghdr* cmsg_hdr;
uint8_t cmsgbuf[CMSG_SPACE(sizeof(int)) + CMSG_SPACE(sizeof(*ipi))];
std::memset(&cmsgbuf, 0, sizeof(cmsgbuf));
msghdr.msg_control = &cmsgbuf;
msghdr.msg_controllen = sizeof(cmsgbuf);
// hop limit
cmsg_hdr = CMSG_FIRSTHDR(&msghdr);
cmsg_hdr->cmsg_level = IPPROTO_IPV6;
cmsg_hdr->cmsg_type = IPV6_HOPLIMIT;
cmsg_hdr->cmsg_len = CMSG_LEN(sizeof(int));
cmsgbuf[sizeof(*cmsg_hdr)] = 255; // using CMSG_DATA throws a warning
// packet info
cmsg_hdr = CMSG_NXTHDR(&msghdr, cmsg_hdr);
cmsg_hdr->cmsg_level = IPPROTO_IPV6;
cmsg_hdr->cmsg_type = IPV6_PKTINFO;
cmsg_hdr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
ipi = (struct in6_pktinfo *) CMSG_DATA(cmsg_hdr);
ipi->ipi6_ifindex = if_nametoindex(interface.c_str());
if (!ipi->ipi6_ifindex) {
std::cerr << "Interface '" << interface << "' not found!\n";
return 3;
}
in6_addr s_addr;
std::memset(&s_addr, 0, sizeof(s_addr));
if (set_src_addr(interface, s_addr)) {
std::cerr << "Error finding link-local address of interface '" << interface << "'!\n";
return 4;
}
std::memcpy(&ipi->ipi6_addr, &s_addr, sizeof(ipi->ipi6_addr));
msghdr.msg_iovlen = 1;
my_ra.opt_prefix_info.nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
my_ra.opt_prefix_info.nd_opt_pi_len = 4;
if (inet_pton(AF_INET6, prefix.c_str(), &my_ra.opt_prefix_info.nd_opt_pi_prefix) != 1) {
std::cerr << "Error converting prefix '" << prefix << "'!\n";
return 5;
}
my_ra.opt_prefix_info.nd_opt_pi_prefix_len = 64;
if (check_prefix(interface, my_ra.opt_prefix_info.nd_opt_pi_prefix)) {
std::cerr << "Prefix " << prefix << " seems to be in use!\n";
return 6;
}
my_ra.opt_prefix_info.nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO;
my_ra.opt_prefix_info.nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_RADDR;
// Setting both lifetimes to 1 means the kernel will only delete the
// link-local address without creating it before.
my_ra.opt_prefix_info.nd_opt_pi_valid_time = htonl(1);
my_ra.opt_prefix_info.nd_opt_pi_preferred_time = htonl(1);
int sock = ::socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
if (sock < 0) {
std::cerr << "Error opening raw socket, are you root?\n";
return 7;
}
if (::sendmsg(sock, &msghdr, 0) < 0) {
::close(sock);
std::cerr << "Error sending RA ( " << strerror(errno) << ")!\n";
return 8;
}
::close(sock);
std::cout << "Sent a Router Advertisment with prefix " <<
prefix << " to " << destination << "\n";
return 0;
}