commit 06cb8e92034274c6f803e97a17cd07fedf99bde5
author Erik Kline <ek@google.com> Wed Mar 30 18:57:13 2016 +0900
committer Erik Kline <ek@google.com> Wed Mar 30 20:06:36 2016 +0900
tree 810a53d217cb4e246a833fa5ba71bfb53c1a5880
parent b3cf2e0f3d3b9ba328921cd1c9c3839ea70a1ab1

Set IFA_BROADCAST during IPv4 RTM_NEWADDRs

Bug: 27194345
Bug: 27732412
Bug: 27786864
Change-Id: I5a5b41422bbaab4582c268c213b788f61cb0e169

libnetutils/ifc_utils.c

diff --git a/libnetutils/ifc_utils.c b/libnetutils/ifc_utils.c
index e0a9f7f..f9f62f8 100644
--- a/libnetutils/ifc_utils.c
+++ b/libnetutils/ifc_utils.c
@@ -259,10 +259,12 @@
     struct {
         struct nlmsghdr n;
         struct ifaddrmsg r;
-        // Allow for IPv6 address, headers, and padding.
+        // Allow for IPv6 address, headers, IPv4 broadcast addr and padding.
         char attrbuf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
                      NLMSG_ALIGN(sizeof(struct rtattr)) +
-                     NLMSG_ALIGN(INET6_ADDRLEN)];
+                     NLMSG_ALIGN(INET6_ADDRLEN) +
+                     NLMSG_ALIGN(sizeof(struct rtattr)) +
+                     NLMSG_ALIGN(INET_ADDRLEN)];
     } req;
     struct rtattr *rta;
     struct nlmsghdr *nh;
@@ -317,6 +319,16 @@
     req.n.nlmsg_len = NLMSG_ALIGN(req.n.nlmsg_len) + RTA_LENGTH(addrlen);
     memcpy(RTA_DATA(rta), addr, addrlen);
 
+    // Add an explicit IFA_BROADCAST for IPv4 RTM_NEWADDRs.
+    if (ss.ss_family == AF_INET && action == RTM_NEWADDR) {
+        rta = (struct rtattr *) (((char *) &req) + NLMSG_ALIGN(req.n.nlmsg_len));
+        rta->rta_type = IFA_BROADCAST;
+        rta->rta_len = RTA_LENGTH(addrlen);
+        req.n.nlmsg_len = NLMSG_ALIGN(req.n.nlmsg_len) + RTA_LENGTH(addrlen);
+        ((struct in_addr *)addr)->s_addr |= htonl((1<<(32-prefixlen))-1);
+        memcpy(RTA_DATA(rta), addr, addrlen);
+    }
+
     s = socket(PF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
     if (s < 0) {
         return -errno;