odhcpd: rework IPv6 interface address dump

Rework the IPv6 address dump logic to make it more robust
and generate syslog traces in case of error situations

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

diff --git a/src/odhcpd.c b/src/odhcpd.c
index 6a3ba868436d5c7f5eacbe02b7893858d4a66d6a..5e0597711fe9954b6e5eec9c5f3068b03a6a6259 100644 (file)
--- a/src/odhcpd.c
+++ b/src/odhcpd.c
@@ -29,6 +29,7 @@
 #include <net/if.h>
 #include <netinet/ip6.h>
 #include <netpacket/packet.h>
+#include <linux/netlink.h>
 #include <linux/rtnetlink.h>
 
 #include <sys/socket.h>
@@ -236,48 +237,56 @@ ssize_t odhcpd_get_interface_addresses(int ifindex,
                                        continue;
 
                                syslog(LOG_WARNING, "Failed to receive IPv6 address rtnetlink message (%s)", strerror(errno));
-                               return ret;
+                               ret = -1;
+                               goto out;
                        }
                }
 
-               if (nhm->nlmsg_type != RTM_NEWADDR) {
-                       syslog(LOG_WARNING, "Unexpected rtnetlink message (%d) in response to IPv6 address dump", nhm->nlmsg_type);
-                       break;
-               }
-
-               // Skip address but keep clearing socket buffer
-               if (ret >= (ssize_t)cnt)
-                       continue;
+               switch (nhm->nlmsg_type) {
+               case RTM_NEWADDR: {
+                       // Skip address but keep clearing socket buffer
+                       if (ret >= (ssize_t)cnt)
+                               continue;
 
-               struct ifaddrmsg *ifa = NLMSG_DATA(nhm);
-               if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
-                               (ifindex && ifa->ifa_index != (unsigned)ifindex))
-                       continue;
+                       struct ifaddrmsg *ifa = NLMSG_DATA(nhm);
+                       if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
+                                       (ifindex && ifa->ifa_index != (unsigned)ifindex))
+                               continue;
 
-               struct rtattr *rta = (struct rtattr*)&ifa[1];
-               size_t alen = NLMSG_PAYLOAD(nhm, sizeof(*ifa));
-               memset(&addrs[ret], 0, sizeof(addrs[ret]));
-               addrs[ret].prefix = ifa->ifa_prefixlen;
-
-               while (RTA_OK(rta, alen)) {
-                       if (rta->rta_type == IFA_ADDRESS) {
-                               memcpy(&addrs[ret].addr, RTA_DATA(rta),
-                                               sizeof(struct in6_addr));
-                       } else if (rta->rta_type == IFA_CACHEINFO) {
-                               struct ifa_cacheinfo *ifc = RTA_DATA(rta);
-                               addrs[ret].preferred = ifc->ifa_prefered;
-                               addrs[ret].valid = ifc->ifa_valid;
+                       struct rtattr *rta = (struct rtattr*)&ifa[1];
+                       size_t alen = NLMSG_PAYLOAD(nhm, sizeof(*ifa));
+                       memset(&addrs[ret], 0, sizeof(addrs[ret]));
+                       addrs[ret].prefix = ifa->ifa_prefixlen;
+
+                       while (RTA_OK(rta, alen)) {
+                               if (rta->rta_type == IFA_ADDRESS) {
+                                       memcpy(&addrs[ret].addr, RTA_DATA(rta),
+                                                       sizeof(struct in6_addr));
+                               } else if (rta->rta_type == IFA_CACHEINFO) {
+                                       struct ifa_cacheinfo *ifc = RTA_DATA(rta);
+                                       addrs[ret].preferred = ifc->ifa_prefered;
+                                       addrs[ret].valid = ifc->ifa_valid;
+                               }
+
+                               rta = RTA_NEXT(rta, alen);
                        }
 
-                       rta = RTA_NEXT(rta, alen);
-               }
+                       if (ifa->ifa_flags & IFA_F_DEPRECATED)
+                               addrs[ret].preferred = 0;
 
-               if (ifa->ifa_flags & IFA_F_DEPRECATED)
-                       addrs[ret].preferred = 0;
+                       ++ret;
+                       break;
+               }
+               case NLMSG_DONE:
+                       goto out;
+               default:
+                       syslog(LOG_WARNING, "Unexpected rtnetlink message (%d) in response to IPv6 address dump", nhm->nlmsg_type);
+                       ret = -1;
+                       goto out;
+               }
 
-               ++ret;
        }
-
+out:
        return ret;
 }