Support parsing RDNSS ND options from netlink. (b185e90d) · Commits · e / os / android_system_core

include/sysutils/NetlinkEvent.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -36,6 +36,7 @@ public:
		const static int NlActionLinkUp;
		const static int NlActionAddressUpdated;
		const static int NlActionAddressRemoved;
		const static int NlActionRdnss;

		NetlinkEvent();
		virtual ~NetlinkEvent();
		@@ -49,9 +50,10 @@ public:
		void dump();

		protected:
		bool parseIfAddrMessage(int type, struct ifaddrmsg *ifaddr, int rtasize);
		bool parseBinaryNetlinkMessage(char *buffer, int size);
		bool parseAsciiNetlinkMessage(char *buffer, int size);
		bool parseIfAddrMessage(int type, struct ifaddrmsg *ifaddr, int rtasize);
		bool parseNdUserOptMessage(struct nduseroptmsg *msg, int optsize);
		};

		#endif

libsysutils/src/NetlinkEvent.cpp

+121 −4

Original line number	Diff line number	Diff line
		@@ -24,6 +24,7 @@
		#include <sys/types.h>
		#include <sys/socket.h>
		#include <netinet/in.h>
		#include <netinet/icmp6.h>
		#include <arpa/inet.h>
		#include <net/if.h>

		@@ -44,6 +45,7 @@ const int NetlinkEvent::NlActionLinkUp = 4;
		const int NetlinkEvent::NlActionLinkDown = 5;
		const int NetlinkEvent::NlActionAddressUpdated = 6;
		const int NetlinkEvent::NlActionAddressRemoved = 7;
		const int NetlinkEvent::NlActionRdnss = 8;

		NetlinkEvent::NetlinkEvent() {
		mAction = NlActionUnknown;
		@@ -76,7 +78,7 @@ void NetlinkEvent::dump() {
		}

		/*
		* Decode a RTM_NEWADDR or RTM_DELADDR message.
		* Parse a RTM_NEWADDR or RTM_DELADDR message.
		*/
		bool NetlinkEvent::parseIfAddrMessage(int type, struct ifaddrmsg *ifaddr,
		int rtasize) {
		@@ -172,13 +174,111 @@ bool NetlinkEvent::parseIfAddrMessage(int type, struct ifaddrmsg *ifaddr,
		}

		/*
		* Parse an binary message from a NETLINK_ROUTE netlink socket.
		* Parse a RTM_NEWNDUSEROPT message.
		*/
		bool NetlinkEvent::parseNdUserOptMessage(struct nduseroptmsg *msg, int len) {
		// Check the length is valid.
		if (msg->nduseropt_opts_len > len) {
		SLOGE("RTM_NEWNDUSEROPT invalid length %d > %d\n",
		msg->nduseropt_opts_len, len);
		return false;
		}
		len = msg->nduseropt_opts_len;

		// Check address family and packet type.
		if (msg->nduseropt_family != AF_INET6) {
		SLOGE("RTM_NEWNDUSEROPT message for unknown family %d\n",
		msg->nduseropt_family);
		return false;
		}

		if (msg->nduseropt_icmp_type != ND_ROUTER_ADVERT \|\|
		msg->nduseropt_icmp_code != 0) {
		SLOGE("RTM_NEWNDUSEROPT message for unknown ICMPv6 type/code %d/%d\n",
		msg->nduseropt_icmp_type, msg->nduseropt_icmp_code);
		return false;
		}

		// Find the interface name.
		char ifname[IFNAMSIZ + 1];
		if (!if_indextoname(msg->nduseropt_ifindex, ifname)) {
		SLOGE("RTM_NEWNDUSEROPT on unknown ifindex %d\n",
		msg->nduseropt_ifindex);
		return false;
		}

		// The kernel sends a separate netlink message for each ND option in the RA.
		// So only parse the first ND option in the message.
		struct nd_opt_hdr opthdr = (struct nd_opt_hdr ) (msg + 1);

		// The length is in multiples of 8 octets.
		uint16_t optlen = opthdr->nd_opt_len;
		if (optlen * 8 > len) {
		SLOGE("Invalid option length %d > %d for ND option %d\n",
		optlen * 8, len, opthdr->nd_opt_type);
		return false;
		}

		if (opthdr->nd_opt_type == ND_OPT_RDNSS) {
		// DNS Servers (RFC 6106).
		// Each address takes up 2*8 octets, and the header takes up 8 octets.
		// So for a valid option with one or more addresses, optlen must be
		// odd and greater than 1.
		if ((optlen < 3) \|\| !(optlen & 0x1)) {
		SLOGE("Invalid optlen %d for RDNSS option\n", optlen);
		return false;
		}
		int numaddrs = (optlen - 1) / 2;

		// Find the lifetime.
		struct nd_opt_rdnss rndss_opt = (struct nd_opt_rdnss ) opthdr;
		uint32_t lifetime = ntohl(rndss_opt->nd_opt_rdnss_lifetime);

		// Construct "SERVERS=<comma-separated string of DNS addresses>".
		// Reserve (INET6_ADDRSTRLEN + 1) chars for each address: all but the
		// the last address are followed by ','; the last is followed by '\0'.
		static const char kServerTag[] = "SERVERS=";
		static const int kTagLength = sizeof(kServerTag) - 1;
		int bufsize = kTagLength + numaddrs * (INET6_ADDRSTRLEN + 1);
		char buf = (char ) malloc(bufsize);
		if (!buf) {
		SLOGE("RDNSS option: out of memory\n");
		return false;
		}
		strcpy(buf, kServerTag);
		int pos = kTagLength;

		struct in6_addr addrs = (struct in6_addr ) (rndss_opt + 1);
		for (int i = 0; i < numaddrs; i++) {
		if (i > 0) {
		buf[pos++] = ',';
		}
		inet_ntop(AF_INET6, addrs + i, buf + pos, bufsize - pos);
		pos += strlen(buf + pos);
		}
		buf[pos] = '\0';

		mAction = NlActionRdnss;
		mSubsystem = strdup("net");
		asprintf(&mParams[0], "INTERFACE=%s", ifname);
		asprintf(&mParams[1], "LIFETIME=%u", lifetime);
		mParams[2] = buf;
		} else {
		SLOGD("Unknown ND option type %d\n", opthdr->nd_opt_type);
		return false;
		}

		return true;
		}

		/*
		* Parse a binary message from a NETLINK_ROUTE netlink socket.
		*/
		bool NetlinkEvent::parseBinaryNetlinkMessage(char *buffer, int size) {
		const struct nlmsghdr *nh;

		for (nh = (struct nlmsghdr *) buffer;
		NLMSG_OK(nh, size) && (nh->nlmsg_type != NLMSG_DONE);
		NLMSG_OK(nh, (unsigned) size) && (nh->nlmsg_type != NLMSG_DONE);
		nh = NLMSG_NEXT(nh, size)) {

		if (nh->nlmsg_type == RTM_NEWLINK) {
		@@ -245,8 +345,25 @@ bool NetlinkEvent::parseBinaryNetlinkMessage(char *buffer, int size) {
		if (!parseIfAddrMessage(nh->nlmsg_type, ifa, rtasize)) {
		continue;
		}

		} else if (nh->nlmsg_type == RTM_NEWNDUSEROPT) {
		int len = nh->nlmsg_len - sizeof(*nh);
		struct nduseroptmsg ndmsg = (struct nduseroptmsg ) NLMSG_DATA(nh);

		if (sizeof(*ndmsg) > (size_t) len) {
		SLOGE("Got a short RTM_NEWNDUSEROPT message\n");
		continue;
		}

		size_t optsize = NLMSG_PAYLOAD(nh, sizeof(*ndmsg));
		if (!parseNdUserOptMessage(ndmsg, optsize)) {
		continue;
		}


		} else {
		SLOGD("Unexpected netlink message. type=0x%x\n", nh->nlmsg_type);
		SLOGD("Unexpected netlink message. type=0x%x\n",
		nh->nlmsg_type);
		}
		}