mgmt: Cleanup handling of extended messages

OpenFlow has a maximum messages size of 65536 bytes, but management
messages can be greater than that.  The management protocol's Extended
Data message is used to get around that limitation.  This commit cleans
up some problems with our implementation and adds some additional
sanity-checking to received messages.

Related to vNetManager Bug #1843.

diff --git a/include/openflow/openflow-mgmt.h b/include/openflow/openflow-mgmt.h
index c3b62c9..04017d4 100644 (file)
--- a/include/openflow/openflow-mgmt.h
+++ b/include/openflow/openflow-mgmt.h
@@ -243,7 +243,8 @@ enum ofmp_extended_data_flags {
 
 /* Body of extended data message.  May be sent by either the switch or the
  * controller to send messages that are greater than 65535 bytes in
- * length.
+ * length.  The OpenFlow transaction id (xid) must be the same for all
+ * the individual OpenFlow messages that make up an extended message.
  *
  * OFMPT_EXTENDED_DATA (switch <-> controller) */
 struct ofmp_extended_data {

diff --git a/vswitchd/mgmt.c b/vswitchd/mgmt.c
index e6e7d4e..d15b4ba 100644 (file)
--- a/vswitchd/mgmt.c
+++ b/vswitchd/mgmt.c
@@ -54,6 +54,7 @@ static struct rconn *mgmt_rconn;
 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(60, 60);
 static struct svec capabilities;
 static struct ofpbuf ext_data_buffer;
+static uint32_t ext_data_xid = UINT32_MAX;
 uint64_t mgmt_id;
 
 
@@ -222,6 +223,10 @@ mgmt_reconfigure(void)
     if (retval == EAFNOSUPPORT) {
         VLOG_ERR("no support for %s vconn", controller_name);
     }
+
+    /* Reset the extended message buffer when we create a new
+     * management connection. */
+    ofpbuf_clear(&ext_data_buffer);
 }
 
 static void *
@@ -261,12 +266,18 @@ send_openflow_buffer(struct ofpbuf *buffer)
         return EINVAL;
     }
 
+    /* Make sure there's room to transmit the data.  We don't want to
+     * fail part way through a send. */
+    if (rconn_packet_counter_read(txqlen) >= TXQ_LIMIT) {
+        return EAGAIN;
+    }
+
     /* OpenFlow messages use a 16-bit length field, so messages over 64K
      * must be broken into multiple pieces. 
      */
     if (buffer->size <= 65535) {
         update_openflow_length(buffer);
-        retval = rconn_send_with_limit(mgmt_rconn, buffer, txqlen, TXQ_LIMIT);
+        retval = rconn_send(mgmt_rconn, buffer, txqlen);
         if (retval) {
             VLOG_WARN_RL(&rl, "send to %s failed: %s",
                          rconn_get_name(mgmt_rconn), strerror(retval));
@@ -292,12 +303,10 @@ send_openflow_buffer(struct ofpbuf *buffer)
                     &new_buffer);
             oed->type = header->type;
 
-            if (remain > 65535) {
+            if (remain > new_len) {
                 oed->flags |= OFMPEDF_MORE_DATA;
             }
 
-            printf("xxx SENDING LEN: %d\n", new_len);
-
             /* Copy the entire original message, including the OpenFlow
              * header, since management protocol structure definitions
              * include these headers.
@@ -305,8 +314,7 @@ send_openflow_buffer(struct ofpbuf *buffer)
             ofpbuf_put(new_buffer, ptr, new_len);
 
             update_openflow_length(new_buffer);
-            retval = rconn_send_with_limit(mgmt_rconn, new_buffer, txqlen, 
-                    TXQ_LIMIT);
+            retval = rconn_send(mgmt_rconn, new_buffer, txqlen);
             if (retval) {
                 VLOG_WARN_RL(&rl, "send to %s failed: %s",
                              rconn_get_name(mgmt_rconn), strerror(retval));
@@ -670,23 +678,48 @@ static int
 recv_ofmp_extended_data(uint32_t xid, const struct ofmp_header *ofmph,
         size_t len)
 {
-    size_t data_len;
+    int data_len;
     struct ofmp_extended_data *ofmped;
-    uint8_t *ptr;
 
-    data_len = len - sizeof(*ofmped);
-    if (data_len <= sizeof(*ofmped)) {
+    if (len <= sizeof(*ofmped)) {
         /* xxx Send error. */
         return -EINVAL;
     }
 
+    ext_data_xid = xid;
     ofmped = (struct ofmp_extended_data *)ofmph;
 
-    ptr = ofpbuf_put(&ext_data_buffer, ofmped->data, data_len);
+    data_len = len - sizeof(*ofmped);
+    ofpbuf_put(&ext_data_buffer, ofmped->data, data_len);
+
+    if (!(ofmped->flags & OFMPEDF_MORE_DATA)) {
+        struct ofmp_header *new_oh;
+        int error;
+
+        /* An embedded message must be greater than the size of an
+         * OpenFlow message. */
+        new_oh = ofpbuf_at(&ext_data_buffer, 0, 65536);
+        if (!new_oh) {
+            VLOG_WARN_RL(&rl, "received short embedded message: %d\n",
+                    ext_data_buffer.size);
+            return -EINVAL;
+        }
+
+        /* Make sure that this is a management message and that there's
+         * not an embedded extended data message. */
+        if ((new_oh->header.vendor != htonl(NX_VENDOR_ID))
+                || (new_oh->header.subtype != htonl(NXT_MGMT))
+                || (new_oh->type == htonl(OFMPT_EXTENDED_DATA))) {
+            VLOG_WARN_RL(&rl, "received bad embedded message\n");
+            return -EINVAL;
+        }
+        new_oh->header.header.xid = ext_data_xid;
+        new_oh->header.header.length = 0;
 
-    if (!ofmped->flags & OFMPEDF_MORE_DATA) {
-        recv_ofmp(xid, ext_data_buffer.data, ext_data_buffer.size);
+        error = recv_ofmp(xid, ext_data_buffer.data, ext_data_buffer.size);
         ofpbuf_clear(&ext_data_buffer);
+
+        return error;
     }
 
     return 0;
@@ -707,6 +740,12 @@ int recv_ofmp(uint32_t xid, struct ofmp_header *ofmph, size_t len)
         len = ntohs(ofmph->header.header.length);
     }
 
+    /* Reset the extended data buffer if this isn't a continuation of an 
+     * existing extended data message. */
+    if (ext_data_xid != xid) {
+        ofpbuf_clear(&ext_data_buffer);
+    }
+
     /* xxx Should sanity-check for min/max length */
     switch (ntohs(ofmph->type)) 
     {