Add error codes for Open Flow v1.2

* Where Open Flow 1.2 breaks apart error codes defined
  in previous versions, provide all new definitions to
  previous versions and map the numeric error code to
  the first first definition supplied in ofp-errors.h.
  The case handled so far is:
  OFPERR_OFPBIC_BAD_EXP_TYPE -> { OFPERR_OFPBIC_BAD_EXPERIMENTER,
                                  OFPERR_OFPBIC_BAD_EXP_TYPE }

* Where Open Flow 1.2 adds error codes that were previously
  defined as Nicira extension errors define the later in terms
  of the new codes.

Signed-off-by: Simon Horman <horms@verge.net.au>
[blp@nicira.com added better error checking in extract-ofp-errors, added
 unit tests, miscellaneous cleanup]
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Simon Horman <horms@verge.net.au>

lib/ofp-errors.c

@@ -25,9 +25,17 @@ ofperr_domain_from_version(uint8_t version)
 {
     return (version == ofperr_of10.version ? &ofperr_of10
             : version == ofperr_of11.version ? &ofperr_of11
+            : version == ofperr_of12.version ? &ofperr_of12
             : NULL);
 }
 
+/* Returns the name (e.g. "OpenFlow 1.0") of OpenFlow error domain 'domain'. */
+const char *
+ofperr_domain_get_name(const struct ofperr_domain *domain)
+{
+    return domain->name;
+}
+
 /* Returns true if 'error' is a valid OFPERR_* value, false otherwise. */
 bool
 ofperr_is_valid(enum ofperr error)
@@ -97,6 +105,24 @@ ofperr_get_name(enum ofperr error)
             : "<invalid>");
 }
 
+/* Returns the OFPERR_* value that corresponds for 'name', 0 if none exists.
+ * For example, returns OFPERR_OFPHFC_INCOMPATIBLE if 'name' is
+ * "OFPHFC_INCOMPATIBLE".
+ *
+ * This is probably useful only for debugging and testing. */
+enum ofperr
+ofperr_from_name(const char *name)
+{
+    int i;
+
+    for (i = 0; i < OFPERR_N_ERRORS; i++) {
+        if (!strcmp(name, error_names[i])) {
+            return i + OFPERR_OFS;
+        }
+    }
+    return 0;
+}
+
 /* Returns an extended description name of 'error', e.g. "ofp_header.type not
  * supported." if 'error' is OFPBRC_BAD_TYPE, or "<invalid>" if 'error' is not
  * a valid OFPERR_* value. */
@@ -108,6 +134,15 @@ ofperr_get_description(enum ofperr error)
             : "<invalid>");
 }
 
+static const struct pair *
+ofperr_get_pair__(enum ofperr error, const struct ofperr_domain *domain)
+{
+    size_t ofs = error - OFPERR_OFS;
+
+    assert(ofperr_is_valid(error));
+    return &domain->errors[ofs];
+}
+
 static struct ofpbuf *
 ofperr_encode_msg__(enum ofperr error, const struct ofperr_domain *domain,
                     ovs_be32 xid, const void *data, size_t data_len)
@@ -115,7 +150,6 @@ ofperr_encode_msg__(enum ofperr error, const struct ofperr_domain *domain,
     struct ofp_error_msg *oem;
     const struct pair *pair;
     struct ofpbuf *buf;
-    size_t ofs;
 
     if (!domain) {
         return NULL;
@@ -140,8 +174,7 @@ ofperr_encode_msg__(enum ofperr error, const struct ofperr_domain *domain,
         return NULL;
     }
 
-    ofs = error - OFPERR_OFS;
-    pair = &domain->errors[ofs];
+    pair = ofperr_get_pair__(error, domain);
     if (!ofperr_is_nx_extension(error)) {
         oem = make_openflow_xid(data_len + sizeof *oem, OFPT_ERROR, xid, &buf);
         oem->type = htons(pair->type);
@@ -210,6 +243,28 @@ ofperr_encode_hello(enum ofperr error, const struct ofperr_domain *domain,
     return ofperr_encode_msg__(error, domain, htonl(0), s, strlen(s));
 }
 
+/* Returns the value that would go into an OFPT_ERROR message's 'type' for
+ * encoding 'error' in 'domain'.  Returns -1 if 'error' is not encodable in
+ * 'domain'.
+ *
+ * 'error' must be a valid OFPERR_* code, as checked by ofperr_is_valid(). */
+int
+ofperr_get_type(enum ofperr error, const struct ofperr_domain *domain)
+{
+    return ofperr_get_pair__(error, domain)->type;
+}
+
+/* Returns the value that would go into an OFPT_ERROR message's 'code' for
+ * encoding 'error' in 'domain'.  Returns -1 if 'error' is not encodable in
+ * 'domain' or if 'error' represents a category rather than a specific error.
+ *
+ * 'error' must be a valid OFPERR_* code, as checked by ofperr_is_valid(). */
+int
+ofperr_get_code(enum ofperr error, const struct ofperr_domain *domain)
+{
+    return ofperr_get_pair__(error, domain)->code;
+}
+
 /* Tries to decodes 'oh', which should be an OpenFlow OFPT_ERROR message.
  * Returns an OFPERR_* constant on success, 0 on failure.
  *