Add functionality to reply to NS packets which are destined for a proxied interface.

Uses netlink sockets to learn the addresses on the proxied
interfaces so that NS packets can be replied to (with a NA)
when the address is present.

Signed-off-by: Carl Smith <carl.smith@alliedtelesis.co.nz>

Makefile

@@ -9,11 +9,13 @@ CXX     ?= g++
 GZIP    ?= /bin/gzip
 MANDIR  ?= ${DESTDIR}${PREFIX}/share/man
 SBINDIR ?= ${DESTDIR}${PREFIX}/sbin
+PKG_CONFIG ?= pkg-config
 
-LIBS     =
+LIBS     = `${PKG_CONFIG} --libs glib-2.0 libnl-3.0 libnl-route-3.0` -pthread
+CPPFLAGS = `${PKG_CONFIG} --cflags glib-2.0 libnl-3.0 libnl-route-3.0`
 
 OBJS     = src/logger.o src/ndppd.o src/iface.o src/proxy.o src/address.o \
-           src/rule.o src/session.o src/conf.o src/route.o
+           src/rule.o src/session.o src/conf.o src/route.o src/nd-netlink.o
 
 all: ndppd ndppd.1.gz ndppd.conf.5.gz nd-proxy
 
@@ -35,7 +37,7 @@ ndppd: ${OBJS}
 	${CXX} -o ndppd ${LDFLAGS} ${LIBS} ${OBJS}
 
 nd-proxy: nd-proxy.c
-	${CXX} -o nd-proxy -Wall -Werror ${LDFLAGS} `pkg-config --cflags glib-2.0` nd-proxy.c `pkg-config --libs glib-2.0`
+	${CXX} -o nd-proxy -Wall -Werror ${LDFLAGS} `${PKG_CONFIG} --cflags glib-2.0` nd-proxy.c `${PKG_CONFIG} --libs glib-2.0`
 
 .cc.o:
 	${CXX} -c ${CPPFLAGS} $(CXXFLAGS) -o $@ $<

src/nd-netlink.cc

@@ -0,0 +1,275 @@
+//
+//@file nd-netlink.cc
+//
+// Copyright 2016, Allied Telesis Labs New Zealand, Ltd
+//
+// 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, either version 3 of the License, or
+// (at your option) any later version.
+//
+// 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.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include <sys/socket.h>
+#include <errno.h>
+#include <netlink/route/addr.h>
+#include <arpa/inet.h>
+#include "ndppd.h"
+#include <algorithm>
+
+NDPPD_NS_BEGIN
+
+pthread_mutex_t cs_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+struct in6_addr*
+address_create_ipv6(struct in6_addr *local)
+{
+    struct in6_addr *addr = (struct in6_addr *)calloc(1, sizeof(struct in6_addr));
+    memcpy(addr, local, sizeof(struct in6_addr));
+    return addr;
+}
+
+void if_add_to_list(int ifindex, const ptr<iface>& ifa)
+{
+    bool found = false;
+
+    pthread_mutex_lock (&cs_mutex);
+    for (std::vector<interface>::iterator it = interfaces.begin();
+            it != interfaces.end(); it++) {
+        if ((*it).ifindex == ifindex) {
+            found = true;
+            break;
+        }
+    }
+    if (!found) {
+        logger::debug() << "rule::add_iface() if=" << ifa->name();
+        interface anInterface;
+        anInterface._name = ifa->name();
+        anInterface.ifindex = ifindex;
+        interfaces.push_back(anInterface);
+    }
+    pthread_mutex_unlock (&cs_mutex);
+}
+
+void
+if_addr_add(int ifindex, struct in6_addr *iaddr)
+{
+    pthread_mutex_lock (&cs_mutex);
+    for (std::vector<interface>::iterator it = interfaces.begin();
+         it != interfaces.end(); it++) {
+        if ((*it).ifindex == ifindex) {
+            address addr = address(*iaddr);
+            logger::debug() << "Adding addr " << addr.to_string();
+            std::list<address>::iterator it_addr;
+            it_addr = std::find((*it).addresses.begin(), (*it).addresses.end(), addr);
+            if (it_addr == (*it).addresses.end()) {
+                (*it).addresses.push_back(addr);
+            }
+            break;
+        }
+    }
+    free(iaddr);
+    pthread_mutex_unlock (&cs_mutex);
+}
+
+void
+if_addr_del(int ifindex, struct in6_addr *iaddr)
+{
+    pthread_mutex_lock (&cs_mutex);
+    for (std::vector<interface>::iterator it = interfaces.begin();
+         it != interfaces.end(); it++) {
+        if ((*it).ifindex == ifindex) {
+            address addr = address(*iaddr);
+            logger::debug() << "Deleting addr " << addr.to_string();
+            (*it).addresses.remove(addr);
+            break;
+        }
+    }
+    free(iaddr);
+    pthread_mutex_unlock (&cs_mutex);
+}
+
+bool
+if_addr_find(std::string iface, const struct in6_addr *iaddr)
+{
+    bool found = false;
+
+    pthread_mutex_lock (&cs_mutex);
+    for (std::vector<interface>::iterator it = interfaces.begin();
+         it != interfaces.end(); it++) {
+        if (iface.compare((*it)._name) == 0) {
+            address addr = address(*iaddr);
+            std::list<address>::iterator it_addr;
+            it_addr = std::find((*it).addresses.begin(), (*it).addresses.end(), addr);
+            if (it_addr != (*it).addresses.end()) {
+                found = true;
+                break;
+            }
+        }
+    }
+    pthread_mutex_unlock (&cs_mutex);
+    return found;
+}
+
+static void
+nl_msg_newaddr(struct nlmsghdr *hdr)
+{
+    struct ifaddrmsg *ifaddr =
+        (struct ifaddrmsg *)(((char *) hdr) + (sizeof(struct nlmsghdr)));
+    // parse the attributes
+    struct nlattr *attrs[IFA_MAX + 1];
+    struct nlattr *s = (struct nlattr *)(((char *) ifaddr) + (sizeof(struct ifaddrmsg)));
+    int len = nlmsg_datalen(hdr) - sizeof(struct ifinfomsg);
+    memset(&attrs, '\0', sizeof(attrs));
+    nla_parse(attrs, IFA_MAX, s, len, NULL);
+
+    struct in6_addr* addr = NULL;
+
+    if (ifaddr->ifa_family == AF_INET6) {
+        addr = address_create_ipv6((struct in6_addr *)nla_data(attrs[IFA_ADDRESS]));
+        if_addr_add(ifaddr->ifa_index, addr);
+    }
+}
+
+static void
+nl_msg_deladdr(struct nlmsghdr *hdr)
+{
+    struct ifaddrmsg *ifaddr =
+        (struct ifaddrmsg *)(((char *) hdr) + (sizeof(struct nlmsghdr)));
+    // parse the attributes
+    struct nlattr *attrs[IFA_MAX + 1];
+    struct nlattr *s = (struct nlattr *)(((char *) ifaddr) + (sizeof(struct ifaddrmsg)));
+    int len = nlmsg_datalen(hdr) - sizeof(struct ifinfomsg);
+    memset(&attrs, '\0', sizeof(attrs));
+    nla_parse(attrs, IFA_MAX, s, len, NULL);
+
+    struct in6_addr* addr = NULL;
+
+    if (ifaddr->ifa_family == AF_INET6) {
+        addr = address_create_ipv6((struct in6_addr *)nla_data(attrs[IFA_ADDRESS]));
+        if_addr_del(ifaddr->ifa_index, addr);
+    }
+}
+
+static void
+new_addr(struct nl_object *obj, void *p)
+{
+    struct rtnl_addr *addr = (struct rtnl_addr *) obj;
+    struct nl_addr *local = rtnl_addr_get_local(addr);
+    int family = rtnl_addr_get_family(addr);
+    int ifindex = rtnl_addr_get_ifindex(addr);
+    struct in6_addr* in_addr = NULL;
+
+    char ipstr[INET6_ADDRSTRLEN];
+    inet_ntop(family, nl_addr_get_binary_addr(local), ipstr, INET6_ADDRSTRLEN);
+
+    switch (family) {
+    case AF_INET:
+        break;
+    case AF_INET6:
+        in_addr = address_create_ipv6((struct in6_addr *)nl_addr_get_binary_addr(local));
+        if_addr_add(ifindex, in_addr);
+        break;
+    default:
+        logger::error() << "Unknown message family: " << family;
+    }
+}
+
+static int
+nl_msg_handler(struct nl_msg *msg, void *arg)
+{
+    logger::debug() << "nl_msg_handler";
+    struct nlmsghdr *hdr = nlmsg_hdr(msg);
+
+    switch (hdr->nlmsg_type) {
+    case RTM_NEWADDR:
+        nl_msg_newaddr(hdr);
+        break;
+    case RTM_DELADDR:
+        nl_msg_deladdr(hdr);
+        break;
+    default:
+        logger::error() << "Unknown message type: " << hdr->nlmsg_type;
+    }
+
+    return NL_OK;
+}
+
+static void *
+netlink_monitor(void *p)
+{
+    struct nl_sock *sock = (struct nl_sock *) p;
+    struct nl_cache *addr_cache;
+
+    // get all the current addresses
+    if (rtnl_addr_alloc_cache(sock, &addr_cache) < 0) {
+        perror("rtnl_addr_alloc_cache");
+        return NULL;
+    }
+
+    // add existing addresses
+    nl_cache_foreach(addr_cache, new_addr, NULL);
+    // destroy the cache
+    nl_cache_free(addr_cache);
+
+    // switch to notification mode
+    // disable sequence checking
+    nl_socket_disable_seq_check(sock);
+    // set the callback we want
+    nl_socket_modify_cb(sock, NL_CB_VALID, NL_CB_CUSTOM, nl_msg_handler, NULL);
+
+    // subscribe to the IPv6 address change callbacks
+    nl_socket_add_memberships(sock, RTNLGRP_IPV6_IFADDR, 0);
+
+    while (1)
+    {
+        nl_recvmsgs_default(sock);
+    }
+    return NULL;
+}
+
+static pthread_t monitor_thread;
+static struct nl_sock *monitor_sock;
+struct nl_sock *control_sock;
+
+bool
+netlink_setup()
+{
+    // create a netlink socket
+    control_sock = nl_socket_alloc();
+    nl_connect(control_sock, NETLINK_ROUTE);
+
+    // create a thread to run the netlink monitor in
+    // create a netlink socket
+    monitor_sock = nl_socket_alloc();
+    nl_connect(monitor_sock, NETLINK_ROUTE);
+    // increase the recv buffer size to capture all notifications
+    nl_socket_set_buffer_size(monitor_sock, 2048000, 0);
+
+    pthread_create(&monitor_thread, NULL, netlink_monitor, monitor_sock);
+    pthread_setname_np(monitor_thread, "netlink");
+    if (pthread_setschedprio(monitor_thread, -10) < 0)
+    {
+        logger::warning() << "setschedprio: " << strerror(errno);
+    }
+    return true;
+}
+
+bool
+netlink_teardown()
+{
+    void *res = 0;
+    pthread_cancel(monitor_thread);
+    pthread_join(monitor_thread, &res);
+    nl_socket_free(monitor_sock);
+    nl_socket_free(control_sock);
+    return true;
+}
+
+NDPPD_NS_END

src/nd-netlink.h

@@ -0,0 +1,28 @@
+//
+// @file nd-netlink.h
+//
+// Copyright 2016, Allied Telesis Labs New Zealand, Ltd
+//
+// 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, either version 3 of the License, or
+// (at your option) any later version.
+//
+// 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.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#pragma once
+
+NDPPD_NS_BEGIN
+
+bool netlink_teardown();
+bool netlink_setup();
+bool if_addr_find(std::string iface, const struct in6_addr *iaddr);
+void if_add_to_list(int ifindex, const ptr<iface>& ifa);
+
+NDPPD_NS_END

src/ndppd.cc

@@ -286,6 +286,8 @@ int main(int argc, char* argv[], char* env[])
 
     gettimeofday(&t1, 0);
 
+    netlink_setup();
+
     while (running) {
         if (iface::poll_all() < 0) {
             if (running) {
@@ -308,6 +310,7 @@ int main(int argc, char* argv[], char* env[])
         session::update_all(elapsed_time);
     }
 
+    netlink_teardown();
     logger::notice() << "Bye";
 
     return 0;

src/ndppd.h

@@ -35,3 +35,4 @@
 #include "proxy.h"
 #include "session.h"
 #include "rule.h"
+#include "nd-netlink.h"

src/proxy.cc

@@ -126,6 +126,11 @@ void proxy::handle_solicit(const address& saddr, const address& daddr,
                 return;
             } else {
                 se->add_iface((*it)->ifa());
+                if (if_addr_find((*it)->ifa()->name(), &taddr.const_addr())) {
+                    logger::debug() << "Sending NA out " << (*it)->ifa()->name();
+                    se->add_iface(_ifa);
+                    se->handle_advert();
+                }
             }
         }
     }

src/rule.cc

@@ -16,6 +16,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <net/if.h>
 
 #include "ndppd.h"
 #include "rule.h"
@@ -24,6 +25,8 @@
 
 NDPPD_NS_BEGIN
 
+std::vector<interface> interfaces;
+
 rule::rule()
 {
 }
@@ -36,6 +39,12 @@ ptr<rule> rule::create(const ptr<proxy>& pr, const address& addr, const ptr<ifac
     ru->_ifa  = ifa;
     ru->_addr = addr;
     ru->_aut  = false;
+    unsigned int ifindex;
+
+    ifindex = if_nametoindex(pr->ifa()->name().c_str());
+    if_add_to_list(ifindex, pr->ifa());
+    ifindex = if_nametoindex(ifa->name().c_str());
+    if_add_to_list(ifindex, ifa);
 
     logger::debug() << "rule::create() if=" << pr->ifa()->name() << ", addr=" << addr;
 

src/rule.h

@@ -18,6 +18,7 @@
 #include <string>
 #include <vector>
 #include <map>
+#include <list>
 
 #include <sys/poll.h>
 
@@ -56,4 +57,19 @@ private:
     rule();
 };
 
+class interface {
+public:
+    // List of IPv6 addresses on this interface
+    std::list<address> addresses;
+
+    // Index of this interface
+    int ifindex;
+
+    // Name of this interface.
+    std::string _name;
+
+};
+
+extern std::vector<interface> interfaces;
+
 NDPPD_NS_END