--- /dev/null
+/*
+ * BFD Data Plane protocol messages header.
+ *
+ * Copyright (C) 2020 Network Device Education Foundation, Inc. ("NetDEF")
+ * Rafael F. Zalamena
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the “Software”), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/**
+ * \file bfddp_packet.h
+ */
+#ifndef BFD_DP_PACKET_H
+#define BFD_DP_PACKET_H
+
+#include <netinet/in.h>
+
+#include <stdint.h>
+
+/*
+ * Protocol definitions.
+ */
+
+/**
+ * BFD protocol version as defined in RFC5880 Section 4.1 Generic BFD Control
+ * Packet Format.
+ */
+#define BFD_PROTOCOL_VERSION 1
+
+/** Default data plane port. */
+#define BFD_DATA_PLANE_DEFAULT_PORT 50700
+
+/** BFD single hop UDP port, as defined in RFC 5881 Section 4. Encapsulation. */
+#define BFD_SINGLE_HOP_PORT 3784
+
+/** BFD multi hop UDP port, as defined in RFC 5883 Section 5. Encapsulation. */
+#define BFD_MULTI_HOP_PORT 4784
+
+/** Default slow start multiplier. */
+#define SLOWSTART_DMULT 3
+/** Default slow start transmission speed. */
+#define SLOWSTART_TX 1000000u
+/** Default slow start receive speed. */
+#define SLOWSTART_RX 1000000u
+/** Default slow start echo receive speed. */
+#define SLOWSTART_ERX 0u
+
+/*
+ * BFD single hop source UDP ports. As defined in RFC 5881 Section 4.
+ * Encapsulation.
+ */
+#define BFD_SOURCE_PORT_BEGIN 49152
+#define BFD_SOURCE_PORT_END 65535
+
+/** BFD data plane protocol version. */
+#define BFD_DP_VERSION 1
+
+/** BFD data plane message types. */
+enum bfddp_message_type {
+ /** Ask for BFD daemon or data plane for echo packet. */
+ ECHO_REQUEST = 0,
+ /** Answer a ECHO_REQUEST packet. */
+ ECHO_REPLY = 1,
+ /** Add or update BFD peer session. */
+ DP_ADD_SESSION = 2,
+ /** Delete BFD peer session. */
+ DP_DELETE_SESSION = 3,
+ /** Tell BFD daemon state changed: timer expired or session down. */
+ BFD_STATE_CHANGE = 4,
+
+ /** Ask for BFD session counters. */
+ DP_REQUEST_SESSION_COUNTERS = 5,
+ /** Tell BFD daemon about counters values. */
+ BFD_SESSION_COUNTERS = 6,
+};
+
+/**
+ * `ECHO_REQUEST`/`ECHO_REPLY` data payload.
+ *
+ * Data plane might use whatever precision it wants for `dp_time`
+ * field, however if you want to be able to tell the delay between
+ * data plane packet send and BFD daemon packet processing you should
+ * use `gettimeofday()` and have the data plane clock synchronized with
+ * BFD daemon (not a problem if data plane runs in the same system).
+ *
+ * Normally data plane will only check the time stamp it sent to determine
+ * the whole packet trip time.
+ */
+struct bfddp_echo {
+ /** Filled by data plane. */
+ uint64_t dp_time;
+ /** Filled by BFD daemon. */
+ uint64_t bfdd_time;
+};
+
+
+/** BFD session flags. */
+enum bfddp_session_flag {
+ /** Set when using multi hop. */
+ SESSION_MULTIHOP = (1 << 0),
+ /** Set when using demand mode. */
+ SESSION_DEMAND = (1 << 1),
+ /** Set when using cbit (Control Plane Independent). */
+ SESSION_CBIT = (1 << 2),
+ /** Set when using echo mode. */
+ SESSION_ECHO = (1 << 3),
+ /** Set when using IPv6. */
+ SESSION_IPV6 = (1 << 4),
+ /** Set when using passive mode. */
+ SESSION_PASSIVE = (1 << 5),
+ /** Set when session is administrative down. */
+ SESSION_SHUTDOWN = (1 << 6),
+};
+
+/**
+ * `DP_ADD_SESSION`/`DP_DELETE_SESSION` data payload.
+ *
+ * `lid` is unique in BFD daemon so it might be used as key for data
+ * structures lookup.
+ */
+struct bfddp_session {
+ /** Important session flags. \see bfddp_session_flag. */
+ uint32_t flags;
+ /**
+ * Session source address.
+ *
+ * Check `flags` field for `SESSION_IPV6` before using as IPv6.
+ */
+ struct in6_addr src;
+ /**
+ * Session destination address.
+ *
+ * Check `flags` field for `SESSION_IPV6` before using as IPv6.
+ */
+ struct in6_addr dst;
+
+ /** Local discriminator. */
+ uint32_t lid;
+ /**
+ * Minimum desired transmission interval (in microseconds) without
+ * jitter.
+ */
+ uint32_t min_tx;
+ /**
+ * Required minimum receive interval rate (in microseconds) without
+ * jitter.
+ */
+ uint32_t min_rx;
+ /**
+ * Required minimum echo receive interval rate (in microseconds)
+ * without jitter.
+ */
+ uint32_t min_echo_rx;
+ /** Amount of milliseconds to wait before starting the session */
+ uint32_t hold_time;
+
+ /** Minimum TTL. */
+ uint8_t ttl;
+ /** Detection multiplier. */
+ uint8_t detect_mult;
+ /** Reserved / zeroed. */
+ uint16_t zero;
+
+ /** Interface index (set to `0` when unavailable). */
+ uint32_t ifindex;
+ /** Interface name (empty when unavailable). */
+ char ifname[64];
+
+ /* TODO: missing authentication. */
+};
+
+/** BFD packet state values as defined in RFC 5880, Section 4.1. */
+enum bfd_state_value {
+ /** Session is administratively down. */
+ STATE_ADMINDOWN = 0,
+ /** Session is down or went down. */
+ STATE_DOWN = 1,
+ /** Session is initializing. */
+ STATE_INIT = 2,
+ /** Session is up. */
+ STATE_UP = 3,
+};
+
+/** BFD diagnostic field values as defined in RFC 5880, Section 4.1. */
+enum bfd_diagnostic_value {
+ /** Nothing was diagnosed. */
+ DIAG_NOTHING = 0,
+ /** Control detection time expired. */
+ DIAG_CONTROL_EXPIRED = 1,
+ /** Echo function failed. */
+ DIAG_ECHO_FAILED = 2,
+ /** Neighbor signaled down. */
+ DIAG_DOWN = 3,
+ /** Forwarding plane reset. */
+ DIAG_FP_RESET = 4,
+ /** Path down. */
+ DIAG_PATH_DOWN = 5,
+ /** Concatenated path down. */
+ DIAG_CONCAT_PATH_DOWN = 6,
+ /** Administratively down. */
+ DIAG_ADMIN_DOWN = 7,
+ /** Reverse concatenated path down. */
+ DIAG_REV_CONCAT_PATH_DOWN = 8,
+};
+
+/** BFD remote state flags. */
+enum bfd_remote_flags {
+ /** Control Plane Independent bit. */
+ RBIT_CPI = (1 << 0),
+ /** Demand mode bit. */
+ RBIT_DEMAND = (1 << 1),
+ /** Multipoint bit. */
+ RBIT_MP = (1 << 2),
+};
+
+/**
+ * `BFD_STATE_CHANGE` data payload.
+ */
+struct bfddp_state_change {
+ /** Local discriminator. */
+ uint32_t lid;
+ /** Remote discriminator. */
+ uint32_t rid;
+ /** Remote configurations/bits set. \see bfd_remote_flags. */
+ uint32_t remote_flags;
+ /** Remote minimum desired transmission interval. */
+ uint32_t desired_tx;
+ /** Remote minimum receive interval. */
+ uint32_t required_rx;
+ /** Remote minimum echo receive interval. */
+ uint32_t required_echo_rx;
+ /** Remote state. \see bfd_state_values.*/
+ uint8_t state;
+ /** Remote diagnostics (if any) */
+ uint8_t diagnostics;
+ /** Remote detection multiplier. */
+ uint8_t detection_multiplier;
+};
+
+/**
+ * BFD control packet state bits definition.
+ */
+enum bfddp_control_state_bits {
+ /** Used to request connection establishment signal. */
+ STATE_POLL_BIT = (1 << 5),
+ /** Finalizes the connection establishment signal. */
+ STATE_FINAL_BIT = (1 << 4),
+ /** Signalizes that forward plane doesn't depend on control plane. */
+ STATE_CPI_BIT = (1 << 3),
+ /** Signalizes the use of authentication. */
+ STATE_AUTH_BIT = (1 << 2),
+ /** Signalizes that peer is using demand mode. */
+ STATE_DEMAND_BIT = (1 << 1),
+ /** Used in RFC 8562 implementation. */
+ STATE_MULTI_BIT = (1 << 0),
+};
+
+/**
+ * BFD control packet.
+ *
+ * As defined in 'RFC 5880 Section 4.1 Generic BFD Control Packet Format'.
+ */
+struct bfddp_control_packet {
+ /** (3 bits version << 5) | (5 bits diag). */
+ uint8_t version_diag;
+ /**
+ * (2 bits state << 6) | (6 bits flags)
+ *
+ * \see bfd_state_value, bfddp_control_state_bits.
+ */
+ uint8_t state_bits;
+ /** Detection multiplier. */
+ uint8_t detection_multiplier;
+ /** Packet length in bytes. */
+ uint8_t length;
+ /** Our discriminator. */
+ uint32_t local_id;
+ /** Remote system discriminator. */
+ uint32_t remote_id;
+ /** Desired minimum send interval in microseconds. */
+ uint32_t desired_tx;
+ /** Desired minimum receive interval in microseconds. */
+ uint32_t required_rx;
+ /** Desired minimum echo receive interval in microseconds. */
+ uint32_t required_echo_rx;
+};
+
+/**
+ * The protocol wire message header structure.
+ */
+struct bfddp_message_header {
+ /** Protocol version format. \see BFD_DP_VERSION. */
+ uint8_t version;
+ /** Reserved / zero field. */
+ uint8_t zero;
+ /** Message contents type. \see bfddp_message_type. */
+ uint16_t type;
+ /**
+ * Message identification (to pair request/response).
+ *
+ * The ID `0` is reserved for asynchronous messages (e.g. unrequested
+ * messages).
+ */
+ uint16_t id;
+ /** Message length. */
+ uint16_t length;
+};
+
+/**
+ * Data plane session counters request.
+ *
+ * Message type: `DP_REQUEST_SESSION_COUNTERS`.
+ */
+struct bfddp_request_counters {
+ /** Session local discriminator. */
+ uint32_t lid;
+};
+
+/**
+ * BFD session counters reply.
+ *
+ * Message type: `BFD_SESSION_COUNTERS`.
+ */
+struct bfddp_session_counters {
+ /** Session local discriminator. */
+ uint32_t lid;
+
+ /** Control packet bytes input. */
+ uint64_t control_input_bytes;
+ /** Control packets input. */
+ uint64_t control_input_packets;
+ /** Control packet bytes output. */
+ uint64_t control_output_bytes;
+ /** Control packets output. */
+ uint64_t control_output_packets;
+
+ /** Echo packet bytes input. */
+ uint64_t echo_input_bytes;
+ /** Echo packets input. */
+ uint64_t echo_input_packets;
+ /** Echo packet bytes output. */
+ uint64_t echo_output_bytes;
+ /** Echo packets output. */
+ uint64_t echo_output_packets;
+};
+
+/**
+ * The protocol wire messages structure.
+ */
+struct bfddp_message {
+ /** Message header. \see bfddp_message_header. */
+ struct bfddp_message_header header;
+
+ /** Message payload. \see bfddp_message_type. */
+ union {
+ struct bfddp_echo echo;
+ struct bfddp_session session;
+ struct bfddp_state_change state;
+ struct bfddp_control_packet control;
+ struct bfddp_request_counters counters_req;
+ struct bfddp_session_counters session_counters;
+ } data;
+};
+
+#endif /* BFD_DP_PACKET_H */
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