ofproto: New action TTL decrement.

Following patch implements dec_ttl as vendor action with similar
semantics as OpenFlow 1.2. If TTL reaches zero while procession
actions in current table, the remaining actions in previous tables
are processed. A configuration parameter is added to make TTL
decrement to zero generate packet in.

Feature #8758
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>

2 files changed, 53 insertions, 2 deletions

diff --git a/utilities/ovs-ofctl.8.in b/utilities/ovs-ofctl.8.in
index 4bfd5436..2a20a2f4 100644
--- a/utilities/ovs-ofctl.8.in
+++ b/utilities/ovs-ofctl.8.in
@@ -243,7 +243,7 @@ If a switch has no controller configured, or if
 the configured controller is disconnected, no traffic is sent, so
 monitoring will not show any traffic.
 .
-.IP "\fBmonitor \fIswitch\fR [\fImiss-len\fR]"
+.IP "\fBmonitor \fIswitch\fR [\fImiss-len\fR] [\fIinvalid_ttl\fR]"
 Connects to \fIswitch\fR and prints to the console all OpenFlow
 messages received.  Usually, \fIswitch\fR should specify the name of a
 bridge in the \fBovs\-vswitchd\fR database.
@@ -256,6 +256,13 @@ does not send these and other asynchronous messages to an
 specified on this argument.  (Thus, if \fImiss\-len\fR is not
 specified, very little traffic will ordinarily be printed.)
 .IP
+.IP
+If \fBinvalid_ttl\fR is passed, \fBovs\-ofctl\fR sends an OpenFlow ``set
+configuration'' message at connection setup time that requests
+\fIINVALID_TTL_TO_CONTROLLER\fR, so that \fBovs\-ofctl monitor\fR can
+receive ``packets-in'' messages when TTL reaches zero on \fBdec_ttl\fR action.
+.IP
+
 This command may be useful for debugging switch or controller
 implementations.
 .
@@ -778,6 +785,16 @@ OpenFlow implementations do not support queuing at all.
 Restores the queue to the value it was before any \fBset_queue\fR
 actions were applied.
 .
+.IP \fBdec_ttl\fR
+Decrement TTL of IPv4 packet or hop limit of IPv6 packet.  If the
+TTL or hop limit is initially zero, no decrement occurs.  Instead,
+a ``packet-in'' message with reason code \fBOFPR_INVALID_TTL\fR is
+sent to each connected controller that has enabled receiving them,
+if any.  Processing the current set of actions then stops.
+However, if the current set of actions was reached through
+``resubmit'' then remaining actions in outer levels resume
+processing.
+.
 .IP \fBnote:\fR[\fIhh\fR]...
 Does nothing at all.  Any number of bytes represented as hex digits
 \fIhh\fR may be included.  Pairs of hex digits may be separated by
diff --git a/utilities/ovs-ofctl.c b/utilities/ovs-ofctl.c
index 6219f94a..8a8b8b2d 100644
--- a/utilities/ovs-ofctl.c
+++ b/utilities/ovs-ofctl.c
@@ -794,6 +794,35 @@ set_packet_in_format(struct vconn *vconn,
              ofputil_packet_in_format_to_string(packet_in_format));
 }
 
+static int
+monitor_set_invalid_ttl_to_controller(struct vconn *vconn)
+{
+    struct ofp_switch_config config;
+    enum ofp_config_flags flags;
+
+    fetch_switch_config(vconn, &config);
+    flags = ntohs(config.flags);
+    if (!(flags & OFPC_INVALID_TTL_TO_CONTROLLER)) {
+        /* Set the invalid ttl config. */
+        flags |= OFPC_INVALID_TTL_TO_CONTROLLER;
+
+        config.flags = htons(flags);
+        set_switch_config(vconn, &config);
+
+        /* Then retrieve the configuration to see if it really took.  OpenFlow
+         * doesn't define error reporting for bad modes, so this is all we can
+         * do. */
+        fetch_switch_config(vconn, &config);
+        flags = ntohs(config.flags);
+        if (!(flags & OFPC_INVALID_TTL_TO_CONTROLLER)) {
+            ovs_fatal(0, "setting invalid_ttl_to_controller failed (this "
+                      "switch probably doesn't support mode)");
+            return -EOPNOTSUPP;
+        }
+    }
+    return 0;
+}
+
 static void
 monitor_vconn(struct vconn *vconn)
 {
@@ -876,6 +905,11 @@ do_monitor(int argc, char *argv[])
         config.miss_send_len = htons(atoi(argv[2]));
         set_switch_config(vconn, &config);
     }
+    if (argc > 3) {
+        if (!strcmp(argv[3], "invalid_ttl")) {
+            monitor_set_invalid_ttl_to_controller(vconn);
+        }
+    }
     monitor_vconn(vconn);
 }
 
@@ -1634,7 +1668,7 @@ do_ofp_print(int argc, char *argv[])
 
 static const struct command all_commands[] = {
     { "show", 1, 1, do_show },
-    { "monitor", 1, 2, do_monitor },
+    { "monitor", 1, 3, do_monitor },
     { "snoop", 1, 1, do_snoop },
     { "dump-desc", 1, 1, do_dump_desc },
     { "dump-tables", 1, 1, do_dump_tables },