Add back 802.1D Spanning Tree Protocol (STP) library code.

At one point, the OVS distribution contained an IEEE 802.1D Spanning
Tree Protocol (STP) library written by Ben Pfaff and based on the
802.1D-1998 reference code.  It was never integrated into ovs-vswitchd,
so it was removed as part of commit ba18611 (Remove vestigial support
for Spanning Tree Protocol.)

This commit reintroduces the library, cleans up a few spots, and makes
it build cleanly against new code.  A future commit will have
ovs-vswitchd use this library.

1 files changed, 100 insertions, 0 deletions

diff --git a/lib/stp.h b/lib/stp.h
new file mode 100644
index 00000000..7eb2cb96
--- /dev/null
+++ b/lib/stp.h
@@ -0,0 +1,100 @@
+/*
+ * Copyright (c) 2008, 2011 Nicira Networks.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef STP_H
+#define STP_H 1
+
+/* This is an implementation of Spanning Tree Protocol as described in IEEE
+ * 802.1D-1998, clauses 8 and 9.  Section numbers refer to this standard.  */
+
+#include <stdbool.h>
+#include <stdint.h>
+#include "compiler.h"
+#include "util.h"
+
+struct ofpbuf;
+
+/* LLC field values used for STP frames. */
+#define STP_LLC_SSAP 0x42
+#define STP_LLC_DSAP 0x42
+#define STP_LLC_CNTL 0x03
+
+/* Bridge and port priorities that should be used by default. */
+#define STP_DEFAULT_BRIDGE_PRIORITY 32768
+#define STP_DEFAULT_PORT_PRIORITY 128
+
+/* Bridge identifier.  Top 16 bits are a priority value (numerically lower
+ * values are higher priorities).  Bottom 48 bits are MAC address of bridge. */
+typedef uint64_t stp_identifier;
+
+/* Basic STP functionality. */
+#define STP_MAX_PORTS 255
+struct stp *stp_create(const char *name, stp_identifier bridge_id,
+                       void (*send_bpdu)(struct ofpbuf *bpdu, int port_no,
+                                         void *aux),
+                       void *aux);
+void stp_destroy(struct stp *);
+void stp_tick(struct stp *, int ms);
+void stp_set_bridge_id(struct stp *, stp_identifier bridge_id);
+void stp_set_bridge_priority(struct stp *, uint16_t new_priority);
+void stp_set_hello_time(struct stp *, int ms);
+void stp_set_max_age(struct stp *, int ms);
+void stp_set_forward_delay(struct stp *, int ms);
+
+/* STP properties. */
+const char *stp_get_name(const struct stp *);
+stp_identifier stp_get_bridge_id(const struct stp *);
+stp_identifier stp_get_designated_root(const struct stp *);
+bool stp_is_root_bridge(const struct stp *);
+int stp_get_root_path_cost(const struct stp *);
+int stp_get_hello_time(const struct stp *);
+int stp_get_max_age(const struct stp *);
+int stp_get_forward_delay(const struct stp *);
+
+/* Obtaining STP ports. */
+struct stp_port *stp_get_port(struct stp *, int port_no);
+struct stp_port *stp_get_root_port(struct stp *);
+bool stp_get_changed_port(struct stp *, struct stp_port **portp);
+
+/* State of an STP port.
+ *
+ * A port is in exactly one state at any given time, but distinct bits are used
+ * for states to allow testing for more than one state with a bit mask. */
+enum stp_state {
+    STP_DISABLED = 1 << 0,       /* 8.4.5: Disabled by management. */
+    STP_LISTENING = 1 << 1,      /* 8.4.2: Not learning or relaying frames. */
+    STP_LEARNING = 1 << 2,       /* 8.4.3: Learning but not relaying frames. */
+    STP_FORWARDING = 1 << 3,     /* 8.4.4: Learning and relaying frames. */
+    STP_BLOCKING = 1 << 4        /* 8.4.1: Initial boot state. */
+};
+const char *stp_state_name(enum stp_state);
+bool stp_forward_in_state(enum stp_state);
+bool stp_learn_in_state(enum stp_state);
+
+void stp_received_bpdu(struct stp_port *, const void *bpdu, size_t bpdu_size);
+
+struct stp *stp_port_get_stp(struct stp_port *);
+int stp_port_no(const struct stp_port *);
+enum stp_state stp_port_get_state(const struct stp_port *);
+void stp_port_enable(struct stp_port *);
+void stp_port_disable(struct stp_port *);
+void stp_port_set_priority(struct stp_port *, uint8_t new_priority);
+void stp_port_set_path_cost(struct stp_port *, uint16_t path_cost);
+void stp_port_set_speed(struct stp_port *, unsigned int speed);
+void stp_port_enable_change_detection(struct stp_port *);
+void stp_port_disable_change_detection(struct stp_port *);
+
+#endif /* stp.h */