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