X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Fofp-util.c;h=d7bc0ee450d43b4465f40f480a354c917f547de1;hb=eb5f3e933b0922d369ad839b2afa1cd7ab764b6e;hp=d773a3fa9f0e8c5e73cf38f18948018ce89dde36;hpb=fa37b408eac875cbc0d7adbbb3f7a004371172da;p=openvswitch

diff --git a/lib/ofp-util.c b/lib/ofp-util.c
index d773a3fa..d7bc0ee4 100644
--- a/lib/ofp-util.c
+++ b/lib/ofp-util.c
@@ -18,14 +18,16 @@
 #include "ofp-print.h"
 #include <inttypes.h>
 #include <stdlib.h>
+#include "byte-order.h"
+#include "nx-match.h"
 #include "ofp-util.h"
 #include "ofpbuf.h"
 #include "packets.h"
 #include "random.h"
-
-#define THIS_MODULE VLM_ofp_util
 #include "vlog.h"
 
+VLOG_DEFINE_THIS_MODULE(ofp_util);
+
 /* Rate limit for OpenFlow message parse errors.  These always indicate a bug
  * in the peer and so there's not much point in showing a lot of them. */
 static struct vlog_rate_limit bad_ofmsg_rl = VLOG_RATE_LIMIT_INIT(1, 5);
@@ -58,6 +60,14 @@ make_openflow(size_t openflow_len, uint8_t type, struct ofpbuf **bufferp)
     return put_openflow_xid(openflow_len, type, alloc_xid(), *bufferp);
 }
 
+/* Similar to make_openflow() but creates a Nicira vendor extension message
+ * with the specific 'subtype'.  'subtype' should be in host byte order. */
+void *
+make_nxmsg(size_t openflow_len, uint32_t subtype, struct ofpbuf **bufferp)
+{
+    return make_nxmsg_xid(openflow_len, subtype, alloc_xid(), bufferp);
+}
+
 /* Allocates and stores in '*bufferp' a new ofpbuf with a size of
  * 'openflow_len', starting with an OpenFlow header with the given 'type' and
  * transaction id 'xid'.  Allocated bytes beyond the header, if any, are
@@ -79,6 +89,19 @@ make_openflow_xid(size_t openflow_len, uint8_t type, uint32_t xid,
     return put_openflow_xid(openflow_len, type, xid, *bufferp);
 }
 
+/* Similar to make_openflow_xid() but creates a Nicira vendor extension message
+ * with the specific 'subtype'.  'subtype' should be in host byte order. */
+void *
+make_nxmsg_xid(size_t openflow_len, uint32_t subtype, uint32_t xid,
+               struct ofpbuf **bufferp)
+{
+    struct nicira_header *nxh = make_openflow_xid(openflow_len, OFPT_VENDOR,
+                                                  xid, bufferp);
+    nxh->vendor = htonl(NX_VENDOR_ID);
+    nxh->subtype = htonl(subtype);
+    return nxh;
+}
+
 /* Appends 'openflow_len' bytes to 'buffer', starting with an OpenFlow header
  * with the given 'type' and an arbitrary transaction id.  Allocated bytes
  * beyond the header, if any, are zeroed.
@@ -124,14 +147,14 @@ put_openflow_xid(size_t openflow_len, uint8_t type, uint32_t xid,
 /* Updates the 'length' field of the OpenFlow message in 'buffer' to
  * 'buffer->size'. */
 void
-update_openflow_length(struct ofpbuf *buffer) 
+update_openflow_length(struct ofpbuf *buffer)
 {
     struct ofp_header *oh = ofpbuf_at_assert(buffer, 0, sizeof *oh);
-    oh->length = htons(buffer->size); 
+    oh->length = htons(buffer->size);
 }
 
 struct ofpbuf *
-make_flow_mod(uint16_t command, const flow_t *flow, size_t actions_len)
+make_flow_mod(uint16_t command, const struct flow *flow, size_t actions_len)
 {
     struct ofp_flow_mod *ofm;
     size_t size = sizeof *ofm + actions_len;
@@ -160,7 +183,7 @@ make_flow_mod(uint16_t command, const flow_t *flow, size_t actions_len)
 }
 
 struct ofpbuf *
-make_add_flow(const flow_t *flow, uint32_t buffer_id,
+make_add_flow(const struct flow *flow, uint32_t buffer_id,
               uint16_t idle_timeout, size_t actions_len)
 {
     struct ofpbuf *out = make_flow_mod(OFPFC_ADD, flow, actions_len);
@@ -172,7 +195,7 @@ make_add_flow(const flow_t *flow, uint32_t buffer_id,
 }
 
 struct ofpbuf *
-make_del_flow(const flow_t *flow)
+make_del_flow(const struct flow *flow)
 {
     struct ofpbuf *out = make_flow_mod(OFPFC_DELETE_STRICT, flow, 0);
     struct ofp_flow_mod *ofm = out->data;
@@ -181,18 +204,23 @@ make_del_flow(const flow_t *flow)
 }
 
 struct ofpbuf *
-make_add_simple_flow(const flow_t *flow,
+make_add_simple_flow(const struct flow *flow,
                      uint32_t buffer_id, uint16_t out_port,
                      uint16_t idle_timeout)
 {
-    struct ofp_action_output *oao;
-    struct ofpbuf *buffer = make_add_flow(flow, buffer_id, idle_timeout,
-                                          sizeof *oao);
-    oao = ofpbuf_put_zeros(buffer, sizeof *oao);
-    oao->type = htons(OFPAT_OUTPUT);
-    oao->len = htons(sizeof *oao);
-    oao->port = htons(out_port);
-    return buffer;
+    if (out_port != OFPP_NONE) {
+        struct ofp_action_output *oao;
+        struct ofpbuf *buffer;
+
+        buffer = make_add_flow(flow, buffer_id, idle_timeout, sizeof *oao);
+        oao = ofpbuf_put_zeros(buffer, sizeof *oao);
+        oao->type = htons(OFPAT_OUTPUT);
+        oao->len = htons(sizeof *oao);
+        oao->port = htons(out_port);
+        return buffer;
+    } else {
+        return make_add_flow(flow, buffer_id, idle_timeout, 0);
+    }
 }
 
 struct ofpbuf *
@@ -258,12 +286,16 @@ struct ofpbuf *
 make_buffered_packet_out(uint32_t buffer_id,
                          uint16_t in_port, uint16_t out_port)
 {
-    struct ofp_action_output action;
-    action.type = htons(OFPAT_OUTPUT);
-    action.len = htons(sizeof action);
-    action.port = htons(out_port);
-    return make_packet_out(NULL, buffer_id, in_port,
-                           (struct ofp_action_header *) &action, 1);
+    if (out_port != OFPP_NONE) {
+        struct ofp_action_output action;
+        action.type = htons(OFPAT_OUTPUT);
+        action.len = htons(sizeof action);
+        action.port = htons(out_port);
+        return make_packet_out(NULL, buffer_id, in_port,
+                               (struct ofp_action_header *) &action, 1);
+    } else {
+        return make_packet_out(NULL, buffer_id, in_port, NULL, 0);
+    }
 }
 
 /* Creates and returns an OFPT_ECHO_REQUEST message with an empty payload. */
@@ -293,7 +325,7 @@ make_echo_reply(const struct ofp_header *rq)
 }
 
 static int
-check_message_type(uint8_t got_type, uint8_t want_type) 
+check_message_type(uint8_t got_type, uint8_t want_type)
 {
     if (got_type != want_type) {
         char *want_type_name = ofp_message_type_to_string(want_type);
@@ -384,50 +416,6 @@ check_ofp_message_array(const struct ofp_header *msg, uint8_t type,
     return 0;
 }
 
-int
-check_ofp_packet_out(const struct ofp_header *oh, struct ofpbuf *data,
-                     int *n_actionsp, int max_ports)
-{
-    const struct ofp_packet_out *opo;
-    unsigned int actions_len, n_actions;
-    size_t extra;
-    int error;
-
-    *n_actionsp = 0;
-    error = check_ofp_message_array(oh, OFPT_PACKET_OUT,
-                                    sizeof *opo, 1, &extra);
-    if (error) {
-        return error;
-    }
-    opo = (const struct ofp_packet_out *) oh;
-
-    actions_len = ntohs(opo->actions_len);
-    if (actions_len > extra) {
-        VLOG_WARN_RL(&bad_ofmsg_rl, "packet-out claims %u bytes of actions "
-                     "but message has room for only %zu bytes",
-                     actions_len, extra);
-        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_LEN);
-    }
-    if (actions_len % sizeof(union ofp_action)) {
-        VLOG_WARN_RL(&bad_ofmsg_rl, "packet-out claims %u bytes of actions, "
-                     "which is not a multiple of %zu",
-                     actions_len, sizeof(union ofp_action));
-        return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_LEN);
-    }
-
-    n_actions = actions_len / sizeof(union ofp_action);
-    error = validate_actions((const union ofp_action *) opo->actions,
-                             n_actions, max_ports);
-    if (error) {
-        return error;
-    }
-
-    data->data = (void *) &opo->actions[n_actions];
-    data->size = extra - actions_len;
-    *n_actionsp = n_actions;
-    return 0;
-}
-
 const struct ofp_flow_stats *
 flow_stats_first(struct flow_stats_iterator *iter,
                  const struct ofp_stats_reply *osr)
@@ -473,9 +461,6 @@ flow_stats_next(struct flow_stats_iterator *iter)
     return fs;
 }
 
-/* Alignment of ofp_actions. */
-#define ACTION_ALIGNMENT 8
-
 static int
 check_action_exact_len(const union ofp_action *a, unsigned int len,
                        unsigned int required_len)
@@ -489,8 +474,11 @@ check_action_exact_len(const union ofp_action *a, unsigned int len,
     return 0;
 }
 
+/* Checks that 'port' is a valid output port for the OFPAT_OUTPUT action, given
+ * that the switch will never have more than 'max_ports' ports.  Returns 0 if
+ * 'port' is valid, otherwise an ofp_mkerr() return code. */
 static int
-check_action_port(int port, int max_ports)
+check_output_port(uint16_t port, int max_ports)
 {
     switch (port) {
     case OFPP_IN_PORT:
@@ -503,7 +491,7 @@ check_action_port(int port, int max_ports)
         return 0;
 
     default:
-        if (port >= 0 && port < max_ports) {
+        if (port < max_ports) {
             return 0;
         }
         VLOG_WARN_RL(&bad_ofmsg_rl, "unknown output port %x", port);
@@ -511,10 +499,37 @@ check_action_port(int port, int max_ports)
     }
 }
 
+/* Checks that 'action' is a valid OFPAT_ENQUEUE action, given that the switch
+ * will never have more than 'max_ports' ports.  Returns 0 if 'port' is valid,
+ * otherwise an ofp_mkerr() return code. */
+static int
+check_enqueue_action(const union ofp_action *a, unsigned int len,
+                     int max_ports)
+{
+    const struct ofp_action_enqueue *oae;
+    uint16_t port;
+    int error;
+
+    error = check_action_exact_len(a, len, 16);
+    if (error) {
+        return error;
+    }
+
+    oae = (const struct ofp_action_enqueue *) a;
+    port = ntohs(oae->port);
+    if (port < max_ports || port == OFPP_IN_PORT) {
+        return 0;
+    }
+    VLOG_WARN_RL(&bad_ofmsg_rl, "unknown enqueue port %x", port);
+    return ofp_mkerr(OFPET_BAD_ACTION, OFPBAC_BAD_OUT_PORT);
+}
+
 static int
-check_nicira_action(const union ofp_action *a, unsigned int len)
+check_nicira_action(const union ofp_action *a, unsigned int len,
+                    const struct flow *flow)
 {
     const struct nx_action_header *nah;
+    int error;
 
     if (len < 16) {
         VLOG_DBG_RL(&bad_ofmsg_rl,
@@ -526,24 +541,69 @@ check_nicira_action(const union ofp_action *a, unsigned int len)
     switch (ntohs(nah->subtype)) {
     case NXAST_RESUBMIT:
     case NXAST_SET_TUNNEL:
+    case NXAST_DROP_SPOOFED_ARP:
+    case NXAST_SET_QUEUE:
+    case NXAST_POP_QUEUE:
         return check_action_exact_len(a, len, 16);
+
+    case NXAST_REG_MOVE:
+        error = check_action_exact_len(a, len,
+                                       sizeof(struct nx_action_reg_move));
+        if (error) {
+            return error;
+        }
+        return nxm_check_reg_move((const struct nx_action_reg_move *) a, flow);
+
+    case NXAST_REG_LOAD:
+        error = check_action_exact_len(a, len,
+                                       sizeof(struct nx_action_reg_load));
+        if (error) {
+            return error;
+        }
+        return nxm_check_reg_load((const struct nx_action_reg_load *) a, flow);
+
+    case NXAST_NOTE:
+        return 0;
+
     default:
         return ofp_mkerr(OFPET_BAD_ACTION, OFPBAC_BAD_VENDOR_TYPE);
     }
 }
 
 static int
-check_action(const union ofp_action *a, unsigned int len, int max_ports)
+check_action(const union ofp_action *a, unsigned int len,
+             const struct flow *flow, int max_ports)
 {
     int error;
 
     switch (ntohs(a->type)) {
     case OFPAT_OUTPUT:
-        error = check_action_port(ntohs(a->output.port), max_ports);
-        return error ? error : check_action_exact_len(a, len, 8);
+        error = check_action_exact_len(a, len, 8);
+        if (error) {
+            return error;
+        }
+        return check_output_port(ntohs(a->output.port), max_ports);
 
     case OFPAT_SET_VLAN_VID:
+        error = check_action_exact_len(a, len, 8);
+        if (error) {
+            return error;
+        }
+        if (a->vlan_vid.vlan_vid & ~htons(0xfff)) {
+            return ofp_mkerr(OFPET_BAD_ACTION, OFPBAC_BAD_ARGUMENT);
+        }
+        return 0;
+
     case OFPAT_SET_VLAN_PCP:
+        error = check_action_exact_len(a, len, 8);
+        if (error) {
+            return error;
+        }
+        if (a->vlan_vid.vlan_vid & ~7) {
+            return ofp_mkerr(OFPET_BAD_ACTION, OFPBAC_BAD_ARGUMENT);
+        }
+        return 0;
+
     case OFPAT_STRIP_VLAN:
     case OFPAT_SET_NW_SRC:
     case OFPAT_SET_NW_DST:
@@ -558,9 +618,12 @@ check_action(const union ofp_action *a, unsigned int len, int max_ports)
 
     case OFPAT_VENDOR:
         return (a->vendor.vendor == htonl(NX_VENDOR_ID)
-                ? check_nicira_action(a, len)
+                ? check_nicira_action(a, len, flow)
                 : ofp_mkerr(OFPET_BAD_ACTION, OFPBAC_BAD_VENDOR));
 
+    case OFPAT_ENQUEUE:
+        return check_enqueue_action(a, len, max_ports);
+
     default:
         VLOG_WARN_RL(&bad_ofmsg_rl, "unknown action type %"PRIu16,
                 ntohs(a->type));
@@ -570,13 +633,14 @@ check_action(const union ofp_action *a, unsigned int len, int max_ports)
 
 int
 validate_actions(const union ofp_action *actions, size_t n_actions,
-                 int max_ports)
+                 const struct flow *flow, int max_ports)
 {
-    const union ofp_action *a;
+    size_t i;
 
-    for (a = actions; a < &actions[n_actions]; ) {
+    for (i = 0; i < n_actions; ) {
+        const union ofp_action *a = &actions[i];
         unsigned int len = ntohs(a->header.len);
-        unsigned int n_slots = len / ACTION_ALIGNMENT;
+        unsigned int n_slots = len / OFP_ACTION_ALIGN;
         unsigned int slots_left = &actions[n_actions] - a;
         int error;
 
@@ -588,21 +652,36 @@ validate_actions(const union ofp_action *actions, size_t n_actions,
         } else if (!len) {
             VLOG_DBG_RL(&bad_ofmsg_rl, "action has invalid length 0");
             return ofp_mkerr(OFPET_BAD_ACTION, OFPBAC_BAD_LEN);
-        } else if (len % ACTION_ALIGNMENT) {
+        } else if (len % OFP_ACTION_ALIGN) {
             VLOG_DBG_RL(&bad_ofmsg_rl, "action length %u is not a multiple "
-                        "of %d", len, ACTION_ALIGNMENT);
+                        "of %d", len, OFP_ACTION_ALIGN);
             return ofp_mkerr(OFPET_BAD_ACTION, OFPBAC_BAD_LEN);
         }
 
-        error = check_action(a, len, max_ports);
+        error = check_action(a, len, flow, max_ports);
         if (error) {
             return error;
         }
-        a += n_slots;
+        i += n_slots;
     }
     return 0;
 }
 
+/* Returns true if 'action' outputs to 'port' (which must be in network byte
+ * order), false otherwise. */
+bool
+action_outputs_to_port(const union ofp_action *action, uint16_t port)
+{
+    switch (ntohs(action->type)) {
+    case OFPAT_OUTPUT:
+        return action->output.port == port;
+    case OFPAT_ENQUEUE:
+        return ((const struct ofp_action_enqueue *) action)->port == port;
+    default:
+        return false;
+    }
+}
+
 /* The set of actions must either come from a trusted source or have been
  * previously validated with validate_actions(). */
 const union ofp_action *
@@ -617,10 +696,10 @@ actions_first(struct actions_iterator *iter,
 const union ofp_action *
 actions_next(struct actions_iterator *iter)
 {
-    if (iter->pos < iter->end) {
+    if (iter->pos != iter->end) {
         const union ofp_action *a = iter->pos;
         unsigned int len = ntohs(a->header.len);
-        iter->pos += len / ACTION_ALIGNMENT;
+        iter->pos += len / OFP_ACTION_ALIGN;
         return a;
     } else {
         return NULL;
@@ -630,7 +709,8 @@ actions_next(struct actions_iterator *iter)
 void
 normalize_match(struct ofp_match *m)
 {
-    enum { OFPFW_NW = OFPFW_NW_SRC_MASK | OFPFW_NW_DST_MASK | OFPFW_NW_PROTO };
+    enum { OFPFW_NW = (OFPFW_NW_SRC_MASK | OFPFW_NW_DST_MASK | OFPFW_NW_PROTO
+                       | OFPFW_NW_TOS) };
     enum { OFPFW_TP = OFPFW_TP_SRC | OFPFW_TP_DST };
     uint32_t wc;
 
@@ -641,7 +721,7 @@ normalize_match(struct ofp_match *m)
         /* Can't sensibly match on network or transport headers if the
          * data link type is unknown. */
         wc |= OFPFW_NW | OFPFW_TP;
-        m->nw_src = m->nw_dst = m->nw_proto = 0;
+        m->nw_src = m->nw_dst = m->nw_proto = m->nw_tos = 0;
         m->tp_src = m->tp_dst = 0;
     } else if (m->dl_type == htons(ETH_TYPE_IP)) {
         if (wc & OFPFW_NW_PROTO) {
@@ -672,6 +752,11 @@ normalize_match(struct ofp_match *m)
         if (wc & OFPFW_NW_DST_MASK) {
             m->nw_dst &= flow_nw_bits_to_mask(wc, OFPFW_NW_DST_SHIFT);
         }
+        if (wc & OFPFW_NW_TOS) {
+            m->nw_tos = 0;
+        } else {
+            m->nw_tos &= IP_DSCP_MASK;
+        }
     } else if (m->dl_type == htons(ETH_TYPE_ARP)) {
         if (wc & OFPFW_NW_PROTO) {
             m->nw_proto = 0;
@@ -682,12 +767,12 @@ normalize_match(struct ofp_match *m)
         if (wc & OFPFW_NW_DST_MASK) {
             m->nw_dst &= flow_nw_bits_to_mask(wc, OFPFW_NW_DST_SHIFT);
         }
-        m->tp_src = m->tp_dst = 0;
+        m->tp_src = m->tp_dst = m->nw_tos = 0;
     } else {
         /* Network and transport layer fields will always be extracted as
          * zeros, so we can do an exact-match on those values. */
         wc &= ~(OFPFW_NW | OFPFW_TP);
-        m->nw_proto = m->nw_src = m->nw_dst = 0;
+        m->nw_proto = m->nw_src = m->nw_dst = m->nw_tos = 0;
         m->tp_src = m->tp_dst = 0;
     }
     if (wc & OFPFW_DL_SRC) {
@@ -699,3 +784,170 @@ normalize_match(struct ofp_match *m)
     m->wildcards = htonl(wc);
 }
 
+/* Returns a string that describes 'match' in a very literal way, without
+ * interpreting its contents except in a very basic fashion.  The returned
+ * string is intended to be fixed-length, so that it is easy to see differences
+ * between two such strings if one is put above another.  This is useful for
+ * describing changes made by normalize_match().
+ *
+ * The caller must free the returned string (with free()). */
+char *
+ofp_match_to_literal_string(const struct ofp_match *match)
+{
+    return xasprintf("wildcards=%#10"PRIx32" "
+                     " in_port=%5"PRId16" "
+                     " dl_src="ETH_ADDR_FMT" "
+                     " dl_dst="ETH_ADDR_FMT" "
+                     " dl_vlan=%5"PRId16" "
+                     " dl_vlan_pcp=%3"PRId8" "
+                     " dl_type=%#6"PRIx16" "
+                     " nw_tos=%#4"PRIx8" "
+                     " nw_proto=%#4"PRIx16" "
+                     " nw_src=%#10"PRIx32" "
+                     " nw_dst=%#10"PRIx32" "
+                     " tp_src=%5"PRId16" "
+                     " tp_dst=%5"PRId16,
+                     ntohl(match->wildcards),
+                     ntohs(match->in_port),
+                     ETH_ADDR_ARGS(match->dl_src),
+                     ETH_ADDR_ARGS(match->dl_dst),
+                     ntohs(match->dl_vlan),
+                     match->dl_vlan_pcp,
+                     ntohs(match->dl_type),
+                     match->nw_tos,
+                     match->nw_proto,
+                     ntohl(match->nw_src),
+                     ntohl(match->nw_dst),
+                     ntohs(match->tp_src),
+                     ntohs(match->tp_dst));
+}
+
+static uint32_t
+vendor_code_to_id(uint8_t code)
+{
+    switch (code) {
+#define OFPUTIL_VENDOR(NAME, VENDOR_ID) case NAME: return VENDOR_ID;
+        OFPUTIL_VENDORS
+#undef OFPUTIL_VENDOR
+    default:
+        return UINT32_MAX;
+    }
+}
+
+/* Creates and returns an OpenFlow message of type OFPT_ERROR with the error
+ * information taken from 'error', whose encoding must be as described in the
+ * large comment in ofp-util.h.  If 'oh' is nonnull, then the error will use
+ * oh->xid as its transaction ID, and it will include up to the first 64 bytes
+ * of 'oh'.
+ *
+ * Returns NULL if 'error' is not an OpenFlow error code. */
+struct ofpbuf *
+make_ofp_error_msg(int error, const struct ofp_header *oh)
+{
+    static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
+
+    struct ofpbuf *buf;
+    const void *data;
+    size_t len;
+    uint8_t vendor;
+    uint16_t type;
+    uint16_t code;
+    uint32_t xid;
+
+    if (!is_ofp_error(error)) {
+        /* We format 'error' with strerror() here since it seems likely to be
+         * a system errno value. */
+        VLOG_WARN_RL(&rl, "invalid OpenFlow error code %d (%s)",
+                     error, strerror(error));
+        return NULL;
+    }
+
+    if (oh) {
+        xid = oh->xid;
+        data = oh;
+        len = ntohs(oh->length);
+        if (len > 64) {
+            len = 64;
+        }
+    } else {
+        xid = 0;
+        data = NULL;
+        len = 0;
+    }
+
+    vendor = get_ofp_err_vendor(error);
+    type = get_ofp_err_type(error);
+    code = get_ofp_err_code(error);
+    if (vendor == OFPUTIL_VENDOR_OPENFLOW) {
+        struct ofp_error_msg *oem;
+
+        oem = make_openflow_xid(len + sizeof *oem, OFPT_ERROR, xid, &buf);
+        oem->type = htons(type);
+        oem->code = htons(code);
+    } else {
+        struct ofp_error_msg *oem;
+        struct nx_vendor_error *nve;
+        uint32_t vendor_id;
+
+        vendor_id = vendor_code_to_id(vendor);
+        if (vendor_id == UINT32_MAX) {
+            VLOG_WARN_RL(&rl, "error %x contains invalid vendor code %d",
+                         error, vendor);
+            return NULL;
+        }
+
+        oem = make_openflow_xid(len + sizeof *oem + sizeof *nve,
+                                OFPT_ERROR, xid, &buf);
+        oem->type = htons(NXET_VENDOR);
+        oem->code = htons(NXVC_VENDOR_ERROR);
+
+        nve = ofpbuf_put_uninit(buf, sizeof *nve);
+        nve->vendor = htonl(vendor_id);
+        nve->type = htons(type);
+        nve->code = htons(code);
+    }
+
+    if (len) {
+        ofpbuf_put(buf, data, len);
+    }
+
+    return buf;
+}
+
+/* Attempts to pull 'actions_len' bytes from the front of 'b'.  Returns 0 if
+ * successful, otherwise an OpenFlow error.
+ *
+ * If successful, the first action is stored in '*actionsp' and the number of
+ * "union ofp_action" size elements into '*n_actionsp'.  Otherwise NULL and 0
+ * are stored, respectively.
+ *
+ * This function does not check that the actions are valid (the caller should
+ * do so, with validate_actions()).  The caller is also responsible for making
+ * sure that 'b->data' is initially aligned appropriately for "union
+ * ofp_action". */
+int
+ofputil_pull_actions(struct ofpbuf *b, unsigned int actions_len,
+                     union ofp_action **actionsp, size_t *n_actionsp)
+{
+    if (actions_len % OFP_ACTION_ALIGN != 0) {
+        VLOG_DBG_RL(&bad_ofmsg_rl, "OpenFlow message actions length %u "
+                    "is not a multiple of %d", actions_len, OFP_ACTION_ALIGN);
+        goto error;
+    }
+
+    *actionsp = ofpbuf_try_pull(b, actions_len);
+    if (*actionsp == NULL) {
+        VLOG_DBG_RL(&bad_ofmsg_rl, "OpenFlow message actions length %u "
+                    "exceeds remaining message length (%zu)",
+                    actions_len, b->size);
+        goto error;
+    }
+
+    *n_actionsp = actions_len / OFP_ACTION_ALIGN;
+    return 0;
+
+error:
+    *actionsp = NULL;
+    *n_actionsp = 0;
+    return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_LEN);
+}