Simplify code that parses ifa_flags.

When parsing an RTM_NEWADDR or RTM_DELADDR, ifaddr is always
present (unless the message is invalid). So ifaddr->ifa_flags is
always known before any attributes are parsed.

Bug: 155005831
Test: atest NetworkStackNextIntegrationTests:IpClientIntegrationTest continues to apss
Change-Id: Id1998faccca7d81c1b7f3e85e4912aa22919e94a

1 files changed, 4 insertions, 6 deletions

diff --git a/libsysutils/src/NetlinkEvent.cpp b/libsysutils/src/NetlinkEvent.cpp
index 3340f8a45..9c1621bc8 100644
--- a/libsysutils/src/NetlinkEvent.cpp
+++ b/libsysutils/src/NetlinkEvent.cpp
@@ -180,7 +180,7 @@ bool NetlinkEvent::parseIfAddrMessage(const struct nlmsghdr *nh) {
     struct ifa_cacheinfo *cacheinfo = nullptr;
     char addrstr[INET6_ADDRSTRLEN] = "";
     char ifname[IFNAMSIZ] = "";
-    uint32_t flags = 0;
+    uint32_t flags;
 
     if (!checkRtNetlinkLength(nh, sizeof(*ifaddr)))
         return false;
@@ -195,6 +195,9 @@ bool NetlinkEvent::parseIfAddrMessage(const struct nlmsghdr *nh) {
     // For log messages.
     const char *msgtype = rtMessageName(type);
 
+    // First 8 bits of flags. In practice will always be overridden when parsing IFA_FLAGS below.
+    flags = ifaddr->ifa_flags;
+
     struct rtattr *rta;
     int len = IFA_PAYLOAD(nh);
     for (rta = IFA_RTA(ifaddr); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
@@ -231,10 +234,6 @@ bool NetlinkEvent::parseIfAddrMessage(const struct nlmsghdr *nh) {
                 SLOGD("Unknown ifindex %d in %s", ifaddr->ifa_index, msgtype);
             }
 
-            // First 8 bits of flags. In practice will always be overridden by the IFA_FLAGS below,
-            // because that always appears after IFA_ADDRESS. But just in case, support both orders.
-            flags = (flags & 0xffffff00) | ifaddr->ifa_flags;
-
         } else if (rta->rta_type == IFA_CACHEINFO) {
             // Address lifetime information.
             if (maybeLogDuplicateAttribute(cacheinfo, "IFA_CACHEINFO", msgtype))
@@ -249,7 +248,6 @@ bool NetlinkEvent::parseIfAddrMessage(const struct nlmsghdr *nh) {
             cacheinfo = (struct ifa_cacheinfo *) RTA_DATA(rta);
 
         } else if (rta->rta_type == IFA_FLAGS) {
-            // In practice IFA_FLAGS is always after IFA_ADDRESS, so this will overwrite the flags.
             flags = *(uint32_t*)RTA_DATA(rta);
         }
     }