[*] Initial commit

lonetix/include/df/bgp/prefix.h

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+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+/**
+ * \file bgp/prefix.h
+ *
+ * Network prefixes types and utilities.
+ *
+ * \copyright The DoubleFourteen Code Forge (C) All Rights Reserved
+ * \author    Lorenzo Cogotti
+ */
+
+#ifndef DF_BGP_PREFIX_H_
+#define DF_BGP_PREFIX_H_
+
+#include "sys/ip.h"
+
+/**
+ * \brief `Afi` values.
+ *
+ * \see [Address family numbers](https://www.iana.org/assignments/address-family-numbers/address-family-numbers.xhtml)
+ *
+ * \note Address family numbers are in network order (big endian).
+ *
+ * @{
+ */
+
+#define AFI_IP  BE16(1)
+#define AFI_IP6 BE16(2)
+
+/**
+ * \brief Address Family Identifier, as defined by the BGP protocol.
+ *
+ * \note Address family numbers are in network order (big endian).
+ */
+typedef Uint16 Afi;
+
+/** @} */
+
+/**
+ * \brief `Safi` values.
+ *
+ * \see [SAFI namespace](https://www.iana.org/assignments/safi-namespace/safi-namespace.xhtml)
+ * \see [RFC 4760](http://www.iana.org/go/rfc4760)
+ *
+ * @{
+ */
+
+#define SAFI_UNICAST   U8_C(1)
+#define SAFI_MULTICAST U8_C(2)
+
+/// Subsequent Address Family Identifier, as defined by the BGP protocol.
+typedef Uint8 Safi;
+
+/** @} */
+
+#pragma pack(push, 1)
+
+/**
+ * \brief BGP prefix with PATH ID information
+ *
+ * \warning **Misaligned struct**.
+ * \note    Fields are in network order (big endian).
+ */
+typedef ALIGNED(1, struct) {
+	Uint32 pathId;  ///< Path identifier
+	Uint8  width;   ///< Prefix length in bits
+
+	/**
+	 * \brief Prefix content `union`.
+	 *
+	 * \warning Only `PFXLEN(width)` bytes are relevant.
+	 */
+	union {
+		Uint8   bytes[16];  ///< Prefix raw bytes
+		Uint16  words[8];   ///< Prefix contents as a sequence of 16-bits values
+		Uint32  dwords[4];  ///< Prefix contents as a sequence of 32-bits values
+		Ipv4adr v4;         ///< Prefix as a **full** IPv4 address
+		Ipv6adr v6;         ///< Prefix as a **full** IPv6 address
+	};
+} ApRawPrefix;
+
+/**
+ * \brief BGP prefix with no PATH ID information.
+ *
+ * \warning **Misaligned struct**.
+ * \note    Fields are in network order (big endian).
+ */
+typedef ALIGNED(1, struct) {
+	Uint8 width;  ///< Prefix length in bits
+
+	/**
+	 * \brief Prefix content `union`.
+	 *
+	 * \warning Only `PFXLEN(width)` bytes are relevant.
+	 */
+	union {
+		Uint8   bytes[16];  ///< Prefix raw bytes
+		Uint16  words[8];   ///< Prefix contents as a sequence of 16-bits values
+		Uint32  dwords[4];  ///< Prefix contents as a sequence of 32-bits values
+		Ipv4adr v4;         ///< Prefix as a **full** IPv4 address
+		Ipv6adr v6;         ///< Prefix as a **full** IPv6 address
+	};
+} RawPrefix;
+
+/**
+ * \brief "Fat" prefix structure, contains both the actual data and metadata about the BGP prefix itself.
+ *
+ * The structure doesn't reflect the actual BGP protocol format,
+ * it is used whenever a raw BGP data pointer isn't sufficient
+ * to convey enough context for a prefix (e.g. iterating every prefix available
+ * inside a BGP message).
+ *
+ * \warning **Misaligned struct**.
+ * \note    Fields are in network order (big endian).
+ *
+ * \note Given the significant amount of metadata, it
+ *       should be used sparingly, raw prefixes should be preferred
+ *       whenever possible to save the overhead.
+ */
+ typedef ALIGNED(1, struct) {
+	Boolean8 isAddPath;  ///< Whether the path identifier is meaningful or not
+	Afi      afi;        ///< Prefix address family
+	Safi     safi;       ///< Prefix subsequent AFI
+	Uint32   pathId;     ///< Path identifier (only meaningful if `isAddPath` is `TRUE`)
+	Uint8    width;      ///< Prefix width, in bits (maximum legal value depends on AFI)
+
+	/**
+	 * \brief Prefix content `union`.
+	 *
+	 * \warning Only `PFXLEN(width)` bytes are relevant.
+	 */
+	union {
+		Uint8   bytes[16];  ///< Prefix raw bytes
+		Uint16  words[8];   ///< Prefix contents as a sequence of 16-bits values
+		Uint32  dwords[4];  ///< Prefix contents as a sequence of 32-bits values
+		Ipv4adr v4;         ///< Prefix as a **full** IPv4 address
+		Ipv6adr v6;         ///< Prefix as a **full** IPv6 address
+	};
+} Prefix;
+
+#pragma pack(pop)
+
+/// Calculate prefix length in bytes from bit width.
+#define PFXLEN(width) ((size_t) (((width) >> 3) + (((width) & 7) != 0)))
+/**
+ * \brief Return pointer to `RawPrefix` portion out of `ApRawPrefix`, `Prefix` or `RawPrefix` itself.
+ *
+ * Cast operation is useful to discard PATH ID information where irrelevant.
+ */
+#define PLAINPFX(prefix) ((RawPrefix *) (&(prefix)->width))
+/// Return pointer to `ApRawPrefix` out of `Prefix` or `ApRawPrefix` itself.
+#define APPFX(prefix) ((ApRawPrefix *) (&(prefix)->pathId))
+
+/// Maximum length of an IPv6 prefix encoded as a string.
+#define PFX6_STRLEN   (IPV6_STRLEN + 1 + 3)
+/// Maximum length of an IPv4 prefix encoded as a string.
+#define PFX4_STRLEN   (IPV4_STRLEN + 1 + 2)
+/// Maximum length of an IPv6 prefix with PATH ID, encoded as a string.
+#define APPFX6_STRLEN (10 + 1 + PFX6_STRLEN)
+/// Maximum length of an IPv4 prefix with PATH ID, encoded as a string.
+#define APPFX4_STRLEN (10 + 1 + PFX4_STRLEN)
+/// Maximum length of a prefix encoded as a string.
+#define PFX_STRLEN    PFX6_STRLEN
+/// Maximum length of a prefix with PATH ID, encoded as a string.
+#define APPFX_STRLEN  APPFX6_STRLEN
+
+/**
+ * Convert a `RawPrefix` of the specified `Afi` to its string representation.
+ *
+ * \return Pointer to the trailing `\0` inside `dest`.
+ *
+ * \note Assumes `dest` is large enough to hold result (use `[PFX_STRLEN + 1]`)
+ */
+char *Bgp_PrefixToString(Afi afi, const RawPrefix *pfx, char *dest);
+/**
+ * Convert an `ApRawPrefix` of the specified `Afi` to its string representation.
+ *
+ * \return Pointer to the trailing `\0` inside `dest`.
+ *
+ * \note Assumes `dest` is large enough to hold result (use `[APPFX_STRLEN + 1]`)
+ */
+char *Bgp_ApPrefixToString(Afi afi, const ApRawPrefix *pfx, char *dest);
+
+/**
+ * \brief Convert string with format `address/width` to `Prefix`.
+ *
+ * \return `OK` on success, `NG` on invalid prefix string.
+ *
+ * \note Does not handle PATH ID, may only return plain prefixes.
+ */
+Judgement Bgp_StringToPrefix(const char *s, Prefix *dest);
+
+/**
+ * \brief Direct iterator over raw prefix data.
+ *
+ * \note `struct` should be considered opaque.
+ */
+typedef struct {
+	Afi      afi;
+	Safi     safi;
+	Boolean8 isAddPath;
+
+	Uint8 *base, *lim;
+	Uint8 *ptr;
+} Prefixiter;
+
+/**
+ * \brief Start iterating `nbytes` bytes from `data` for prefixes of the specified `afi` and `safi`.
+ *
+ * \return `OK` on success, `NG` on error. Sets BGP error, see `Bgp_GetErrStat()`.
+ */
+Judgement Bgp_StartPrefixes(Prefixiter *it, Afi afi, Safi safi, const void *data, size_t nbytes, Boolean isAddPath);
+/**
+ * \brief Get current prefix and advance iterator.
+ *
+ * \return Current prefix on success, depending on `isAddPath` prefix type
+ *         may be either `RawPrefix` or `ApRawPrefix`. `NULL` on iteration end or
+ *         error. Sets BGP error, see `Bgp_GetErrStat()`.
+ */
+void *Bgp_NextPrefix(Prefixiter *it);
+
+#endif