libsysutils/src/NetlinkEvent.cpp - android-core - Git at Google

 /*
  * Copyright (C) 2008 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 #include <stdlib.h>
 #include <string.h>

 #define LOG_TAG "NetlinkEvent"
 #include <cutils/log.h>

 #include <sysutils/NetlinkEvent.h>

 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <netinet/icmp6.h>
 #include <arpa/inet.h>
 #include <net/if.h>

 #include <linux/if.h>
 #include <linux/netfilter/nfnetlink.h>
 #include <linux/netfilter_ipv4/ipt_ULOG.h>
 /* From kernel's net/netfilter/xt_quota2.c */
 const int QLOG_NL_EVENT  = 112;

 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>

 const int NetlinkEvent::NlActionUnknown = 0;
 const int NetlinkEvent::NlActionAdd = 1;
 const int NetlinkEvent::NlActionRemove = 2;
 const int NetlinkEvent::NlActionChange = 3;
 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;
     memset(mParams, 0, sizeof(mParams));
     mPath = NULL;
     mSubsystem = NULL;
 }

 NetlinkEvent::~NetlinkEvent() {
     int i;
     if (mPath)
         free(mPath);
     if (mSubsystem)
         free(mSubsystem);
     for (i = 0; i < NL_PARAMS_MAX; i++) {
         if (!mParams[i])
             break;
         free(mParams[i]);
     }
 }

 void NetlinkEvent::dump() {
     int i;

     for (i = 0; i < NL_PARAMS_MAX; i++) {
         if (!mParams[i])
             break;
         SLOGD("NL param '%s'\n", mParams[i]);
     }
 }

 /*
  * Parse a RTM_NEWADDR or RTM_DELADDR message.
  */
 bool NetlinkEvent::parseIfAddrMessage(int type, struct ifaddrmsg *ifaddr,
                                       int rtasize) {
     struct rtattr *rta;
     struct ifa_cacheinfo *cacheinfo = NULL;
     char addrstr[INET6_ADDRSTRLEN] = "";

     // Sanity check.
     if (type != RTM_NEWADDR && type != RTM_DELADDR) {
         SLOGE("parseIfAddrMessage on incorrect message type 0x%x\n", type);
         return false;
     }

     // For log messages.
     const char *msgtype = (type == RTM_NEWADDR) ? "RTM_NEWADDR" : "RTM_DELADDR";

     for (rta = IFA_RTA(ifaddr); RTA_OK(rta, rtasize);
          rta = RTA_NEXT(rta, rtasize)) {
         if (rta->rta_type == IFA_ADDRESS) {
             // Only look at the first address, because we only support notifying
             // one change at a time.
             if (*addrstr != '\0') {
                 SLOGE("Multiple IFA_ADDRESSes in %s, ignoring\n", msgtype);
                 continue;
             }

             // Convert the IP address to a string.
             if (ifaddr->ifa_family == AF_INET) {
                 struct in_addr *addr4 = (struct in_addr *) RTA_DATA(rta);
                 if (RTA_PAYLOAD(rta) < sizeof(*addr4)) {
                     SLOGE("Short IPv4 address (%d bytes) in %s",
                           RTA_PAYLOAD(rta), msgtype);
                     continue;
                 }
                 inet_ntop(AF_INET, addr4, addrstr, sizeof(addrstr));
             } else if (ifaddr->ifa_family == AF_INET6) {
                 struct in6_addr *addr6 = (struct in6_addr *) RTA_DATA(rta);
                 if (RTA_PAYLOAD(rta) < sizeof(*addr6)) {
                     SLOGE("Short IPv6 address (%d bytes) in %s",
                           RTA_PAYLOAD(rta), msgtype);
                     continue;
                 }
                 inet_ntop(AF_INET6, addr6, addrstr, sizeof(addrstr));
             } else {
                 SLOGE("Unknown address family %d\n", ifaddr->ifa_family);
                 continue;
             }

             // Find the interface name.
             char ifname[IFNAMSIZ + 1];
             if (!if_indextoname(ifaddr->ifa_index, ifname)) {
                 SLOGE("Unknown ifindex %d in %s", ifaddr->ifa_index, msgtype);
                 return false;
             }

             // Fill in interface information.
             mAction = (type == RTM_NEWADDR) ? NlActionAddressUpdated :
                                               NlActionAddressRemoved;
             mSubsystem = strdup("net");
             asprintf(&mParams[0], "ADDRESS=%s/%d", addrstr,
                      ifaddr->ifa_prefixlen);
             asprintf(&mParams[1], "INTERFACE=%s", ifname);
             asprintf(&mParams[2], "FLAGS=%u", ifaddr->ifa_flags);
             asprintf(&mParams[3], "SCOPE=%u", ifaddr->ifa_scope);
         } else if (rta->rta_type == IFA_CACHEINFO) {
             // Address lifetime information.
             if (cacheinfo) {
                 // We only support one address.
                 SLOGE("Multiple IFA_CACHEINFOs in %s, ignoring\n", msgtype);
                 continue;
             }

             if (RTA_PAYLOAD(rta) < sizeof(*cacheinfo)) {
                 SLOGE("Short IFA_CACHEINFO (%d vs. %d bytes) in %s",
                       RTA_PAYLOAD(rta), sizeof(cacheinfo), msgtype);
                 continue;
             }

             cacheinfo = (struct ifa_cacheinfo *) RTA_DATA(rta);
             asprintf(&mParams[4], "PREFERRED=%u", cacheinfo->ifa_prefered);
             asprintf(&mParams[5], "VALID=%u", cacheinfo->ifa_valid);
             asprintf(&mParams[6], "CSTAMP=%u", cacheinfo->cstamp);
             asprintf(&mParams[7], "TSTAMP=%u", cacheinfo->tstamp);
         }
     }

     if (addrstr[0] == '\0') {
         SLOGE("No IFA_ADDRESS in %s\n", msgtype);
         return false;
     }

     return true;
 }

 /*
 <<<<<<< HEAD
  * 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, (unsigned) size) && (nh->nlmsg_type != NLMSG_DONE);
          nh = NLMSG_NEXT(nh, size)) {

         if (nh->nlmsg_type == RTM_NEWLINK) {
             int len = nh->nlmsg_len - sizeof(*nh);
             struct ifinfomsg *ifi;

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

             ifi = (ifinfomsg *)NLMSG_DATA(nh);
             if ((ifi->ifi_flags & IFF_LOOPBACK) != 0) {
                 continue;
             }

             struct rtattr *rta = (struct rtattr *)
               ((char *) ifi + NLMSG_ALIGN(sizeof(*ifi)));
             len = NLMSG_PAYLOAD(nh, sizeof(*ifi));

             while(RTA_OK(rta, len)) {
                 switch(rta->rta_type) {
                 case IFLA_IFNAME:
                     char buffer[16 + IFNAMSIZ];
                     snprintf(buffer, sizeof(buffer), "INTERFACE=%s",
                              (char *) RTA_DATA(rta));
                     mParams[0] = strdup(buffer);
                     mAction = (ifi->ifi_flags & IFF_LOWER_UP) ?
                       NlActionLinkUp : NlActionLinkDown;
                     mSubsystem = strdup("net");
                     break;
                 }

                 rta = RTA_NEXT(rta, len);
             }

         } else if (nh->nlmsg_type == QLOG_NL_EVENT) {
             char *devname;
             ulog_packet_msg_t *pm;
             size_t len = nh->nlmsg_len - sizeof(*nh);
             if (sizeof(*pm) > len) {
                 SLOGE("Got a short QLOG message\n");
                 continue;
             }
             pm = (ulog_packet_msg_t *)NLMSG_DATA(nh);
             devname = pm->indev_name[0] ? pm->indev_name : pm->outdev_name;
             asprintf(&mParams[0], "ALERT_NAME=%s", pm->prefix);
             asprintf(&mParams[1], "INTERFACE=%s", devname);
             mSubsystem = strdup("qlog");
             mAction = NlActionChange;

         } else if (nh->nlmsg_type == RTM_NEWADDR ||
                    nh->nlmsg_type == RTM_DELADDR) {
             int len = nh->nlmsg_len - sizeof(*nh);
             struct ifaddrmsg *ifa;

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

             ifa = (ifaddrmsg *)NLMSG_DATA(nh);
             size_t rtasize = IFA_PAYLOAD(nh);
             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);
         }
     }

     return true;
 }

 /* If the string between 'str' and 'end' begins with 'prefixlen' characters
  * from the 'prefix' array, then return 'str + prefixlen', otherwise return
  * NULL.
  */
 static const char*
 has_prefix(const char* str, const char* end, const char* prefix, size_t prefixlen)
 {
     if ((end-str) >= (ptrdiff_t)prefixlen && !memcmp(str, prefix, prefixlen))
         return str + prefixlen;
     else
         return NULL;
 }

 /* Same as strlen(x) for constant string literals ONLY */
 #define CONST_STRLEN(x)  (sizeof(x)-1)

 /* Convenience macro to call has_prefix with a constant string literal  */
 #define HAS_CONST_PREFIX(str,end,prefix)  has_prefix((str),(end),prefix,CONST_STRLEN(prefix))


 /*
  * Parse an ASCII-formatted message from a NETLINK_KOBJECT_UEVENT
  * netlink socket.
  */
 bool NetlinkEvent::parseAsciiNetlinkMessage(char *buffer, int size) {
     const char *s = buffer;
     const char *end;
     int param_idx = 0;
     int i;
     int first = 1;

     if (size == 0)
         return false;

     /* Ensure the buffer is zero-terminated, the code below depends on this */
     buffer[size-1] = '\0';

     end = s + size;
     while (s < end) {
         if (first) {
             const char *p;
             /* buffer is 0-terminated, no need to check p < end */
             for (p = s; *p != '@'; p++) {
                 if (!*p) { /* no '@', should not happen */
                     return false;
                 }
             }
             mPath = strdup(p+1);
             first = 0;
         } else {
             const char* a;
             if ((a = HAS_CONST_PREFIX(s, end, "ACTION=")) != NULL) {
                 if (!strcmp(a, "add"))
                     mAction = NlActionAdd;
                 else if (!strcmp(a, "remove"))
                     mAction = NlActionRemove;
                 else if (!strcmp(a, "change"))
                     mAction = NlActionChange;
             } else if ((a = HAS_CONST_PREFIX(s, end, "SEQNUM=")) != NULL) {
                 mSeq = atoi(a);
             } else if ((a = HAS_CONST_PREFIX(s, end, "SUBSYSTEM=")) != NULL) {
                 mSubsystem = strdup(a);
             } else if (param_idx < NL_PARAMS_MAX) {
                 mParams[param_idx++] = strdup(s);
             }
         }
         s += strlen(s) + 1;
     }
     return true;
 }

 bool NetlinkEvent::decode(char *buffer, int size, int format) {
     if (format == NetlinkListener::NETLINK_FORMAT_BINARY) {
         return parseBinaryNetlinkMessage(buffer, size);
     } else {
         return parseAsciiNetlinkMessage(buffer, size);
     }
 }

 const char *NetlinkEvent::findParam(const char *paramName) {
     size_t len = strlen(paramName);
     for (int i = 0; i < NL_PARAMS_MAX && mParams[i] != NULL; ++i) {
         const char *ptr = mParams[i] + len;
         if (!strncmp(mParams[i], paramName, len) && *ptr == '=')
             return ++ptr;
     }

     SLOGE("NetlinkEvent::FindParam(): Parameter '%s' not found", paramName);
     return NULL;
 }
	/*
	* Copyright (C) 2008 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	#include <stdlib.h>
	#include <string.h>

	#define LOG_TAG "NetlinkEvent"
	#include <cutils/log.h>

	#include <sysutils/NetlinkEvent.h>

	#include <sys/types.h>
	#include <sys/socket.h>
	#include <netinet/in.h>
	#include <netinet/icmp6.h>
	#include <arpa/inet.h>
	#include <net/if.h>

	#include <linux/if.h>
	#include <linux/netfilter/nfnetlink.h>
	#include <linux/netfilter_ipv4/ipt_ULOG.h>
	/* From kernel's net/netfilter/xt_quota2.c */
	const int QLOG_NL_EVENT = 112;

	#include <linux/netlink.h>
	#include <linux/rtnetlink.h>

	const int NetlinkEvent::NlActionUnknown = 0;
	const int NetlinkEvent::NlActionAdd = 1;
	const int NetlinkEvent::NlActionRemove = 2;
	const int NetlinkEvent::NlActionChange = 3;
	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;
	memset(mParams, 0, sizeof(mParams));
	mPath = NULL;
	mSubsystem = NULL;
	}

	NetlinkEvent::~NetlinkEvent() {
	int i;
	if (mPath)
	free(mPath);
	if (mSubsystem)
	free(mSubsystem);
	for (i = 0; i < NL_PARAMS_MAX; i++) {
	if (!mParams[i])
	break;
	free(mParams[i]);
	}
	}

	void NetlinkEvent::dump() {
	int i;

	for (i = 0; i < NL_PARAMS_MAX; i++) {
	if (!mParams[i])
	break;
	SLOGD("NL param '%s'\n", mParams[i]);
	}
	}

	/*
	* Parse a RTM_NEWADDR or RTM_DELADDR message.
	*/
	bool NetlinkEvent::parseIfAddrMessage(int type, struct ifaddrmsg *ifaddr,
	int rtasize) {
	struct rtattr *rta;
	struct ifa_cacheinfo *cacheinfo = NULL;
	char addrstr[INET6_ADDRSTRLEN] = "";

	// Sanity check.
	if (type != RTM_NEWADDR && type != RTM_DELADDR) {
	SLOGE("parseIfAddrMessage on incorrect message type 0x%x\n", type);
	return false;
	}

	// For log messages.
	const char *msgtype = (type == RTM_NEWADDR) ? "RTM_NEWADDR" : "RTM_DELADDR";

	for (rta = IFA_RTA(ifaddr); RTA_OK(rta, rtasize);
	rta = RTA_NEXT(rta, rtasize)) {
	if (rta->rta_type == IFA_ADDRESS) {
	// Only look at the first address, because we only support notifying
	// one change at a time.
	if (*addrstr != '\0') {
	SLOGE("Multiple IFA_ADDRESSes in %s, ignoring\n", msgtype);
	continue;
	}

	// Convert the IP address to a string.
	if (ifaddr->ifa_family == AF_INET) {
	struct in_addr addr4 = (struct in_addr ) RTA_DATA(rta);
	if (RTA_PAYLOAD(rta) < sizeof(*addr4)) {
	SLOGE("Short IPv4 address (%d bytes) in %s",
	RTA_PAYLOAD(rta), msgtype);
	continue;
	}
	inet_ntop(AF_INET, addr4, addrstr, sizeof(addrstr));
	} else if (ifaddr->ifa_family == AF_INET6) {
	struct in6_addr addr6 = (struct in6_addr ) RTA_DATA(rta);
	if (RTA_PAYLOAD(rta) < sizeof(*addr6)) {
	SLOGE("Short IPv6 address (%d bytes) in %s",
	RTA_PAYLOAD(rta), msgtype);
	continue;
	}
	inet_ntop(AF_INET6, addr6, addrstr, sizeof(addrstr));
	} else {
	SLOGE("Unknown address family %d\n", ifaddr->ifa_family);
	continue;
	}

	// Find the interface name.
	char ifname[IFNAMSIZ + 1];
	if (!if_indextoname(ifaddr->ifa_index, ifname)) {
	SLOGE("Unknown ifindex %d in %s", ifaddr->ifa_index, msgtype);
	return false;
	}

	// Fill in interface information.
	mAction = (type == RTM_NEWADDR) ? NlActionAddressUpdated :
	NlActionAddressRemoved;
	mSubsystem = strdup("net");
	asprintf(&mParams[0], "ADDRESS=%s/%d", addrstr,
	ifaddr->ifa_prefixlen);
	asprintf(&mParams[1], "INTERFACE=%s", ifname);
	asprintf(&mParams[2], "FLAGS=%u", ifaddr->ifa_flags);
	asprintf(&mParams[3], "SCOPE=%u", ifaddr->ifa_scope);
	} else if (rta->rta_type == IFA_CACHEINFO) {
	// Address lifetime information.
	if (cacheinfo) {
	// We only support one address.
	SLOGE("Multiple IFA_CACHEINFOs in %s, ignoring\n", msgtype);
	continue;
	}

	if (RTA_PAYLOAD(rta) < sizeof(*cacheinfo)) {
	SLOGE("Short IFA_CACHEINFO (%d vs. %d bytes) in %s",
	RTA_PAYLOAD(rta), sizeof(cacheinfo), msgtype);
	continue;
	}

	cacheinfo = (struct ifa_cacheinfo *) RTA_DATA(rta);
	asprintf(&mParams[4], "PREFERRED=%u", cacheinfo->ifa_prefered);
	asprintf(&mParams[5], "VALID=%u", cacheinfo->ifa_valid);
	asprintf(&mParams[6], "CSTAMP=%u", cacheinfo->cstamp);
	asprintf(&mParams[7], "TSTAMP=%u", cacheinfo->tstamp);
	}
	}

	if (addrstr[0] == '\0') {
	SLOGE("No IFA_ADDRESS in %s\n", msgtype);
	return false;
	}

	return true;
	}

	/*
	<<<<<<< HEAD
	* 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, (unsigned) size) && (nh->nlmsg_type != NLMSG_DONE);
	nh = NLMSG_NEXT(nh, size)) {

	if (nh->nlmsg_type == RTM_NEWLINK) {
	int len = nh->nlmsg_len - sizeof(*nh);
	struct ifinfomsg *ifi;

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

	ifi = (ifinfomsg *)NLMSG_DATA(nh);
	if ((ifi->ifi_flags & IFF_LOOPBACK) != 0) {
	continue;
	}

	struct rtattr rta = (struct rtattr )
	((char ) ifi + NLMSG_ALIGN(sizeof(ifi)));
	len = NLMSG_PAYLOAD(nh, sizeof(*ifi));

	while(RTA_OK(rta, len)) {
	switch(rta->rta_type) {
	case IFLA_IFNAME:
	char buffer[16 + IFNAMSIZ];
	snprintf(buffer, sizeof(buffer), "INTERFACE=%s",
	(char *) RTA_DATA(rta));
	mParams[0] = strdup(buffer);
	mAction = (ifi->ifi_flags & IFF_LOWER_UP) ?
	NlActionLinkUp : NlActionLinkDown;
	mSubsystem = strdup("net");
	break;
	}

	rta = RTA_NEXT(rta, len);
	}

	} else if (nh->nlmsg_type == QLOG_NL_EVENT) {
	char *devname;
	ulog_packet_msg_t *pm;
	size_t len = nh->nlmsg_len - sizeof(*nh);
	if (sizeof(*pm) > len) {
	SLOGE("Got a short QLOG message\n");
	continue;
	}
	pm = (ulog_packet_msg_t *)NLMSG_DATA(nh);
	devname = pm->indev_name[0] ? pm->indev_name : pm->outdev_name;
	asprintf(&mParams[0], "ALERT_NAME=%s", pm->prefix);
	asprintf(&mParams[1], "INTERFACE=%s", devname);
	mSubsystem = strdup("qlog");
	mAction = NlActionChange;

	} else if (nh->nlmsg_type == RTM_NEWADDR \|\|
	nh->nlmsg_type == RTM_DELADDR) {
	int len = nh->nlmsg_len - sizeof(*nh);
	struct ifaddrmsg *ifa;

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

	ifa = (ifaddrmsg *)NLMSG_DATA(nh);
	size_t rtasize = IFA_PAYLOAD(nh);
	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);
	}
	}

	return true;
	}

	/* If the string between 'str' and 'end' begins with 'prefixlen' characters
	* from the 'prefix' array, then return 'str + prefixlen', otherwise return
	* NULL.
	*/
	static const char*
	has_prefix(const char* str, const char* end, const char* prefix, size_t prefixlen)
	{
	if ((end-str) >= (ptrdiff_t)prefixlen && !memcmp(str, prefix, prefixlen))
	return str + prefixlen;
	else
	return NULL;
	}

	/* Same as strlen(x) for constant string literals ONLY */
	#define CONST_STRLEN(x) (sizeof(x)-1)

	/* Convenience macro to call has_prefix with a constant string literal */
	#define HAS_CONST_PREFIX(str,end,prefix) has_prefix((str),(end),prefix,CONST_STRLEN(prefix))


	/*
	* Parse an ASCII-formatted message from a NETLINK_KOBJECT_UEVENT
	* netlink socket.
	*/
	bool NetlinkEvent::parseAsciiNetlinkMessage(char *buffer, int size) {
	const char *s = buffer;
	const char *end;
	int param_idx = 0;
	int i;
	int first = 1;

	if (size == 0)
	return false;

	/* Ensure the buffer is zero-terminated, the code below depends on this */
	buffer[size-1] = '\0';

	end = s + size;
	while (s < end) {
	if (first) {
	const char *p;
	/* buffer is 0-terminated, no need to check p < end */
	for (p = s; *p != '@'; p++) {
	if (!p) { / no '@', should not happen */
	return false;
	}
	}
	mPath = strdup(p+1);
	first = 0;
	} else {
	const char* a;
	if ((a = HAS_CONST_PREFIX(s, end, "ACTION=")) != NULL) {
	if (!strcmp(a, "add"))
	mAction = NlActionAdd;
	else if (!strcmp(a, "remove"))
	mAction = NlActionRemove;
	else if (!strcmp(a, "change"))
	mAction = NlActionChange;
	} else if ((a = HAS_CONST_PREFIX(s, end, "SEQNUM=")) != NULL) {
	mSeq = atoi(a);
	} else if ((a = HAS_CONST_PREFIX(s, end, "SUBSYSTEM=")) != NULL) {
	mSubsystem = strdup(a);
	} else if (param_idx < NL_PARAMS_MAX) {
	mParams[param_idx++] = strdup(s);
	}
	}
	s += strlen(s) + 1;
	}
	return true;
	}

	bool NetlinkEvent::decode(char *buffer, int size, int format) {
	if (format == NetlinkListener::NETLINK_FORMAT_BINARY) {
	return parseBinaryNetlinkMessage(buffer, size);
	} else {
	return parseAsciiNetlinkMessage(buffer, size);
	}
	}

	const char NetlinkEvent::findParam(const char paramName) {
	size_t len = strlen(paramName);
	for (int i = 0; i < NL_PARAMS_MAX && mParams[i] != NULL; ++i) {
	const char *ptr = mParams[i] + len;
	if (!strncmp(mParams[i], paramName, len) && *ptr == '=')
	return ++ptr;
	}

	SLOGE("NetlinkEvent::FindParam(): Parameter '%s' not found", paramName);
	return NULL;
	}