Parse IP address changes in NetlinkEvent.

This adds support for parsing RTM_NEWADDR and RTM_DELADDR
netlink messages received on netd's netlink socket and
formatting them them so NetlinkHandler can process them.

Address changes are notified in subsystem "address". Interface
changes, which used to be notified in subsystem "net", are now
notified in subsystem "interface" to avoid confusion.

Bug: 10232006
Change-Id: I93a50e8de17014e118a42f5cc0eb90a0cbfa73cc

include/sysutils/NetlinkEvent.h

@@ -47,6 +47,7 @@ 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);
 };

libsysutils/src/NetlinkEvent.cpp

@@ -23,6 +23,10 @@
 
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <netinet/in.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>
@@ -69,6 +73,102 @@ void NetlinkEvent::dump() {
     }
 }
 
+/*
+ * Decode a RTM_NEWADDR or RTM_DELADDR message.
+ */
+bool NetlinkEvent::parseIfAddrMessage(int type, struct ifaddrmsg *ifaddr,
+                                      int rtasize) {
+    struct rtattr *rta = IFA_RTA(ifaddr);
+    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";
+
+    while(RTA_OK(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) ? NlActionAdd : NlActionRemove;
+            mSubsystem = strdup("address");
+            asprintf(&mParams[0], "ADDRESS=%s/%d", addrstr,
+                     ifaddr->ifa_prefixlen);
+            asprintf(&mParams[1], "IFACE=%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);
+        }
+
+        rta = RTA_NEXT(rta, rtasize);
+    }
+
+    if (addrstr[0] == '\0') {
+        SLOGE("No IFA_ADDRESS in %s\n", msgtype);
+        return false;
+    }
+
+    return true;
+}
+
 /*
  * Parse an binary message from a NETLINK_ROUTE netlink socket.
  */
@@ -105,7 +205,7 @@ bool NetlinkEvent::parseBinaryNetlinkMessage(char *buffer, int size) {
                     mParams[0] = strdup(buffer);
                     mAction = (ifi->ifi_flags & IFF_LOWER_UP) ?
                       NlActionLinkUp : NlActionLinkDown;
-                    mSubsystem = strdup("net");
+                    mSubsystem = strdup("interface");
                     break;
                 }
 
@@ -127,6 +227,21 @@ bool NetlinkEvent::parseBinaryNetlinkMessage(char *buffer, int size) {
             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 {
                 SLOGD("Unexpected netlink message. type=0x%x\n", nh->nlmsg_type);
         }