ofp-util: Make ofputil_encode_set_protocol() able to return failure.

Soon, it's not going to be possible to switch between every possible
protocol on an established OpenFlow connection, yet
ofputil_encode_set_protocol() didn't have a documented way to report such
a problem.  This commit adds a means for reporting and makes its callers
able to handle the problem.

Also, initially make ofputil_encode_set_protocol() fail when the current
and requested protocols are for different OpenFlow versions.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Reviewed-by: Simon Horman <horms@verge.net.au>

diff --git a/lib/learning-switch.c b/lib/learning-switch.c
index 7a60f3c32adb92c5fe9fa0f044f66cc6629d8545..eeaa3064395eecd90522765fafd59c21fd767085 100644 (file)
--- a/lib/learning-switch.c
+++ b/lib/learning-switch.c
@@ -200,15 +200,19 @@ lswitch_handshake(struct lswitch *sw)
                 error = rconn_send(sw->rconn, msg, NULL);
             }
         }
+        if (protocol & usable_protocols) {
+            for (i = 0; !error && i < sw->n_default_flows; i++) {
+                msg = ofputil_encode_flow_mod(&sw->default_flows[i], protocol);
+                error = rconn_send(sw->rconn, msg, NULL);
+            }
 
-        for (i = 0; !error && i < sw->n_default_flows; i++) {
-            msg = ofputil_encode_flow_mod(&sw->default_flows[i], protocol);
-            error = rconn_send(sw->rconn, msg, NULL);
-        }
-
-        if (error) {
-            VLOG_INFO_RL(&rl, "%s: failed to queue default flows (%s)",
-                         rconn_get_name(sw->rconn), strerror(error));
+            if (error) {
+                VLOG_INFO_RL(&rl, "%s: failed to queue default flows (%s)",
+                             rconn_get_name(sw->rconn), strerror(error));
+            }
+        } else {
+            VLOG_INFO_RL(&rl, "%s: failed to set usable protocol",
+                         rconn_get_name(sw->rconn));
         }
     }
     sw->protocol = protocol;

diff --git a/lib/ofp-util.c b/lib/ofp-util.c
index 6ff9df894b72564f15693982d00a38aef96250e3..ad3fb369219fe8f666219719be1ef1fa40f4d9a4 100644 (file)
--- a/lib/ofp-util.c
+++ b/lib/ofp-util.c
@@ -1201,15 +1201,25 @@ ofputil_encode_hello(uint32_t allowed_versions)
  * connection if the switch processes the returned message correctly.  (If
  * '*next != want' then the caller will have to iterate.)
  *
- * If 'current == want', returns NULL and stores 'current' in '*next'. */
+ * If 'current == want', or if it is not possible to transition from 'current'
+ * to 'want' (because, for example, 'current' and 'want' use different OpenFlow
+ * protocol versions), returns NULL and stores 'current' in '*next'. */
 struct ofpbuf *
 ofputil_encode_set_protocol(enum ofputil_protocol current,
                             enum ofputil_protocol want,
                             enum ofputil_protocol *next)
 {
+    enum ofp_version cur_version, want_version;
     enum ofputil_protocol cur_base, want_base;
     bool cur_tid, want_tid;
 
+    cur_version = ofputil_protocol_to_ofp_version(current);
+    want_version = ofputil_protocol_to_ofp_version(want);
+    if (cur_version != want_version) {
+        *next = current;
+        return NULL;
+    }
+
     cur_base = ofputil_protocol_to_base(current);
     want_base = ofputil_protocol_to_base(want);
     if (cur_base != want_base) {

diff --git a/utilities/ovs-ofctl.c b/utilities/ovs-ofctl.c
index 914be9840870535b4321d23f35f4d6cd946f3087..08c3aa9272f5f022a70826e3d47497586731733b 100644 (file)
--- a/utilities/ovs-ofctl.c
+++ b/utilities/ovs-ofctl.c
@@ -763,7 +763,7 @@ try_set_protocol(struct vconn *vconn, enum ofputil_protocol want,
 
         request = ofputil_encode_set_protocol(*cur, want, &next);
         if (!request) {
-            return true;
+            return *cur == want;
         }
 
         run(vconn_transact_noreply(vconn, request, &reply),