route-table: Split header and attribute parsing.

In a subsequent patch we will introduce support for handling the
RTA_MULTIPATH attribute.

The RTA_MULTIPATH attribute is a nested attribute containing
another set of route attributes.  There is some overlap of netlink
policy for parsing both sets of attributes.

Consequently we would want to reuse the code for parsing these
attributes, and splitting up the function allows us to do this in
a subsequent patch.

Signed-off-by: Frode Nordahl <[email protected]>
Signed-off-by: 0-day Robot <[email protected]>

lib/route-table.c

@@ -225,7 +225,9 @@ route_table_reset(void)
 /* Return RTNLGRP_IPV4_ROUTE or RTNLGRP_IPV6_ROUTE on success, 0 on parse
  * error. */
 static int
-route_table_parse(struct ofpbuf *buf, void *change_)
+route_table_parse__(struct ofpbuf *buf, size_t ofs,
+                    const struct nlmsghdr *nlmsg,
+                    const struct rtmsg *rtm, void *change_)
 {
     struct route_table_msg *change = change_;
     bool parsed, ipv4 = false;
@@ -251,28 +253,22 @@ route_table_parse(struct ofpbuf *buf, void *change_)
     };
 
     struct nlattr *attrs[ARRAY_SIZE(policy)];
-    const struct rtmsg *rtm;
-
-    rtm = ofpbuf_at(buf, NLMSG_HDRLEN, sizeof *rtm);
 
     if (rtm->rtm_family == AF_INET) {
-        parsed = nl_policy_parse(buf, NLMSG_HDRLEN + sizeof(struct rtmsg),
-                                 policy, attrs, ARRAY_SIZE(policy));
+        parsed = nl_policy_parse(buf, ofs, policy, attrs,
+                                 ARRAY_SIZE(policy));
         ipv4 = true;
     } else if (rtm->rtm_family == AF_INET6) {
-        parsed = nl_policy_parse(buf, NLMSG_HDRLEN + sizeof(struct rtmsg),
-                                 policy6, attrs, ARRAY_SIZE(policy6));
+        parsed = nl_policy_parse(buf, ofs, policy6, attrs,
+                                 ARRAY_SIZE(policy6));
     } else {
         VLOG_DBG_RL(&rl, "received non AF_INET rtnetlink route message");
         return 0;
     }
 
     if (parsed) {
-        const struct nlmsghdr *nlmsg;
         int rta_oif;      /* Output interface index. */
 
-        nlmsg = buf->data;
-
         memset(change, 0, sizeof *change);
         change->relevant = true;
 
@@ -355,6 +351,19 @@ route_table_parse(struct ofpbuf *buf, void *change_)
     return ipv4 ? RTNLGRP_IPV4_ROUTE : RTNLGRP_IPV6_ROUTE;
 }
 
+static int
+route_table_parse(struct ofpbuf *buf, void *change_)
+{
+    struct rtmsg *rtm;
+    struct nlmsghdr *nlmsg;
+
+    nlmsg = ofpbuf_at(buf, 0, NLMSG_HDRLEN);
+    rtm = ofpbuf_at(buf, NLMSG_HDRLEN, sizeof *rtm);
+
+    return route_table_parse__(buf, NLMSG_HDRLEN + sizeof *rtm,
+                               nlmsg, rtm, change_);
+}
+
 static bool
 route_table_standard_table(uint32_t table_id)
 {