Line data    Source code

       1             : #ifndef HEADER_fd_src_ballet_shred_fd_shred_h
       2             : #define HEADER_fd_src_ballet_shred_fd_shred_h
       3             : 
       4             : #include <stdio.h>
       5             : /* Shreds form the on-wire representation of Solana block data
       6             :    optimized for transmission over unreliable links/WAN.
       7             : 
       8             :    ### Layout
       9             : 
      10             :    Each shred is 1228 bytes long.
      11             : 
      12             :       +------------------------+
      13             :       | Common Shred Header    | 83 bytes
      14             :       +------------------------+
      15             :       | Data Header            | 5 bytes
      16             :       | or Coding Header       | or 6 bytes
      17             :       +------------------------+
      18             :       |                        | variable
      19             :       | Payload                | length
      20             :       |                        |
      21             :       +------------------------+
      22             : 
      23             :        for Merkle shreds, followed by:
      24             : 
      25             :       +------------------------+
      26             :       | (Chained merkle root)  | 32 bytes
      27             :       +------------------------+
      28             :       +------------------------+
      29             :       | Merkle node #0 (root)  | 20 bytes
      30             :       +------------------------+
      31             :       | Merkle node #1         | 20 bytes
      32             :       ..........................
      33             : 
      34             :        for resigned shreds shreds, followed by:
      35             : 
      36             :       +------------------------+
      37             :       | signature              | 64 bytes
      38             :       ..........................
      39             : 
      40             :    ### Shredding
      41             : 
      42             :    For a given input data blob (usually an entry batch),
      43             :    data shreds are derived by simply splitting up the blob into subslices.
      44             : 
      45             :    Each shred is sized such that it fits into a single UDP packet,
      46             :    i.e. currently bound by the generally accepted IPv6 MTU of 1280 bytes.
      47             : 
      48             :    ### Forward Error Correction
      49             : 
      50             :    Coding shreds implement Reed-Solomon error correction to provide tolerance against packet loss.
      51             : 
      52             :    Each data shred is first assigned an FEC set.
      53             :    For the vector of data shreds in each set, a corresponding vector of coding shreds contains parity data.
      54             : 
      55             :    FEC sets and entry batches do not necessarily align.
      56             : 
      57             :    ### Merkle Inclusion Proofs
      58             : 
      59             :    Data and coding shreds come in two variants respectively: legacy and merkle.
      60             :    Merkle shreds extend legacy shreds by adding FEC set inclusion proofs.
      61             : 
      62             :    It allows the block producer to commit to the vector of shreds that make up an FEC set.
      63             :    The inclusion proof is used to verify whether a shred is part of the FEC set commitment.
      64             : 
      65             :    The length of the inclusion proof is indicated by the variant field.
      66             : 
      67             :    ### resigned shreds
      68             : 
      69             :    Resigned shreds allow for an additional signature to be added on to lock down
      70             :    the retransmitter for turbine propagation
      71             : 
      72             :    ### Authentication
      73             : 
      74             :    Shreds are signed by the block producer.
      75             :    Consequentially, only the block producer is able to create valid shreds for any given block. */
      76             : 
      77             : #include "../fd_ballet.h"
      78             : 
      79             : /* FD_SHRED_MAX_SZ: The max byte size of a shred.
      80             :    This limit derives from the IPv6 MTU of 1280 bytes, minus 48 bytes
      81             :    for the UDP/IPv6 headers and another 4 bytes for good measure.  Most
      82             :    shreds are this size, but Merkle data shreds may be smaller. */
      83   102428826 : #define FD_SHRED_MAX_SZ (1228UL)
      84             : /* FD_SHRED_MIN_SZ: The minimum byte size of a shred.
      85             :    A code shred of the max size covers a data shred of the minimum size
      86             :    with no padding. */
      87   102427233 : #define FD_SHRED_MIN_SZ (1203UL)
      88             : /* FD_SHRED_DATA_HEADER_SZ: size of all headers for data type shreds. */
      89   100564068 : #define FD_SHRED_DATA_HEADER_SZ (0x58UL)
      90             : /* FD_SHRED_CODE_HEADER_SZ: size of all headers for coding type shreds. */
      91    51177402 : #define FD_SHRED_CODE_HEADER_SZ (0x59UL)
      92             : 
      93             : /* FD_SHRED_TYPE_* identifies the type of a shred.
      94             :    It is located at the four high bits of byte 0x40 (64) of the shred header
      95             :    and can be extracted using the fd_shred_type() function. */
      96             : /* FD_SHRED_TYPE_LEGACY_DATA: A shred carrying raw binary data. */
      97   105967074 : #define FD_SHRED_TYPE_LEGACY_DATA ((uchar)0xA0)
      98             : /* FD_SHRED_TYPE_LEGACY_CODE: A shred carrying Reed-Solomon ECC. */
      99             : #define FD_SHRED_TYPE_LEGACY_CODE ((uchar)0x50)
     100             : /* FD_SHRED_TYPE_MERKLE_DATA: A shred carrying raw binary data and a merkle inclusion proof. */
     101    54984906 : #define FD_SHRED_TYPE_MERKLE_DATA ((uchar)0x80)
     102             : /* FD_SHRED_TYPE_MERKLE_CODE: A shred carrying Reed-Solomon ECC and a merkle inclusion proof. */
     103   153215931 : #define FD_SHRED_TYPE_MERKLE_CODE ((uchar)0x40)
     104             : /* FD_SHRED_TYPE_MERKLE_DATA_CHAINED: A shred carrying raw binary data and a chained merkle inclusion proof. */
     105       23292 : #define FD_SHRED_TYPE_MERKLE_DATA_CHAINED ((uchar)0x90)
     106             : /* FD_SHRED_TYPE_MERKLE_CODE_CHAINED: A shred carrying Reed-Solomon ECC and a chained merkle inclusion proof. */
     107       22428 : #define FD_SHRED_TYPE_MERKLE_CODE_CHAINED ((uchar)0x60)
     108             : 
     109             : /* FD_SHRED_TYPE_MERKLE_DATA_CHAINED_RESIGNED: A shred carrying raw binary data and a chained merkle inclusion proof and resigned. */
     110   101486664 : #define FD_SHRED_TYPE_MERKLE_DATA_CHAINED_RESIGNED ((uchar)0xB0)
     111             : /* FD_SHRED_TYPE_MERKLE_CODE_CHAINED_RESIGNED: A shred carrying Reed-Solomon ECC and a chained merkle inclusion proof and resigned. */
     112   101485032 : #define FD_SHRED_TYPE_MERKLE_CODE_CHAINED_RESIGNED ((uchar)0x70)
     113             : 
     114             : /* FD_SHRED_TYPEMASK_DATA: bitwise AND with type matches data shred */
     115             : #define FD_SHRED_TYPEMASK_DATA FD_SHRED_TYPE_MERKLE_DATA
     116             : /* FD_SHRED_TYPEMASK_CODE: bitwise AND with type matches code shred */
     117   101457426 : #define FD_SHRED_TYPEMASK_CODE FD_SHRED_TYPE_MERKLE_CODE
     118             : 
     119             : /* FD_SHRED_MERKLE_ROOT_SZ: the size of a merkle tree root in bytes. */
     120       21945 : #define FD_SHRED_MERKLE_ROOT_SZ (32UL)
     121             : /* FD_SHRED_MERKLE_NODE_SZ: the size of a merkle inclusion proof node in bytes. */
     122   102946059 : #define FD_SHRED_MERKLE_NODE_SZ (20UL)
     123             : /* FD_SHRED_MERKLE_LAYER_CNT: the count of inclusion proof layers in the binary merkle tree. */
     124         159 : #define FD_SHRED_MERKLE_LAYER_CNT (10UL)
     125             : /* FD_SHRED_SIGNATURE_SZ: the size of a signature in a shred. */
     126   101467497 : #define FD_SHRED_SIGNATURE_SZ (64UL)
     127             : /* A merkle inclusion proof node. */
     128             : typedef uchar fd_shred_merkle_t[FD_SHRED_MERKLE_NODE_SZ];
     129             : 
     130             : /* Constants relating to the data shred "flags" field. */
     131             : 
     132             : /* Mask of the "reference tick"    field in shred.data.flags */
     133           0 : #define FD_SHRED_DATA_REF_TICK_MASK      ((uchar)0x3f)
     134             : /* Mask of the "slot complete"       bit in shred.data.flags
     135             :    Indicates the last shred in a slot. */
     136           0 : #define FD_SHRED_DATA_FLAG_SLOT_COMPLETE ((uchar)0x80)
     137             : /* Mask of the "data batch complete" bit in shred.data.flags */
     138             : #define FD_SHRED_DATA_FLAG_DATA_COMPLETE ((uchar)0x40)
     139             : 
     140             : /* Maximum number of data shreds in a slot, also maximum number of parity shreds in a slot */
     141           0 : #define FD_SHRED_MAX_PER_SLOT (1 << 15UL) /* 32,768 shreds */
     142             : 
     143             : /* Offset of the shred variant. Used for parsing. */
     144             : #define FD_SHRED_VARIANT_OFF 0x40
     145             : 
     146             : /* Firedancer-specific internal error codes.
     147             : 
     148             :    These are not part of the Solana protocol. */
     149             : 
     150           0 : #define FD_SHRED_EBATCH  0x4000 /* End of batch reached (success)
     151             :                                    no more shreds and found FD_SHRED_DATA_FLAG_DATA_COMPLETE */
     152           0 : #define FD_SHRED_ESLOT   0x8000 /* End of slot reached (success)
     153             :                                    no more shreds and found FD_SHRED_DATA_FLAG_SLOT_COMPLETE */
     154           0 : #define FD_SHRED_ENOMEM      12 /* Error: Target buffer too small */
     155           0 : #define FD_SHRED_EINVAL      22 /* Error: Invalid shred data */
     156           0 : #define FD_SHRED_EPIPE       32 /* Error: Expected data in source buffer, got EOF */
     157             : 
     158             : /* Primary shred data structure.
     159             :    Relies heavily on packed fields and unaligned memory accesses. */
     160             : struct __attribute__((packed)) fd_shred {
     161             :   /* Ed25519 signature over the shred
     162             : 
     163             :      For legacy type shreds, signs over content of the shred structure past this signature field.
     164             :      For merkle type shreds, signs over the first node of the inclusion proof (merkle root). */
     165             :   /* 0x00 */ fd_ed25519_sig_t signature;
     166             : 
     167             :   /* Shred variant specifier
     168             :      Consists of two four bit fields. (Deliberately not using bit fields here)
     169             : 
     170             :      The high four bits indicate the shred type:
     171             :      - 0101: legacy code
     172             :      - 1010: legacy data
     173             :      - 0100: merkle code
     174             :      - 0110: merkle code (chained)
     175             :      - 0111: merkle code (chained resigned)
     176             :      - 1000: merkle data
     177             :      - 1001: merkle data (chained)
     178             :      - 1011: merkle data (chained resigned)
     179             : 
     180             :      For legacy type shreds, the low four bits are set to static patterns.
     181             :      For merkle type shreds, the low four bits are set to the number of non-root nodes in the inclusion proof.
     182             :      For merkle code type shreds, the 3rd highest bit represents if the merkle tree is chained.
     183             :      For merkle data type shreds, the 4th highest bit represents if the merkle tree is chained.
     184             :      For merkle code type shreds, the 4th highest bit represents if the shred is resigned.
     185             :      For merkle data type shreds, the 3th highest bit represents if the shred is resigned.
     186             : */
     187             :   /* 0x40 */ uchar  variant;
     188             : 
     189             :   /* Slot number that this shred is part of */
     190             :   /* 0x41 */ ulong  slot;
     191             : 
     192             :   /* Index of this shred within the slot */
     193             :   /* 0x49 */ uint   idx;
     194             : 
     195             :   /* Hash of the genesis version and historical hard forks of the current chain */
     196             :   /* 0x4d */ ushort version;
     197             : 
     198             :   /* Index into the vector of FEC sets for this slot. For data shreds, fec_set_idx<=idx. */
     199             :   /* 0x4f */ uint   fec_set_idx;
     200             : 
     201             :   union {
     202             :     /* Common data shred header */
     203             :     struct __attribute__((packed)) {
     204             :       /* Slot number difference between this block and the parent block.
     205             :          parent_off <= slot.
     206             :          Always greater than zero, except for slot 0, in which case the
     207             :          previous invariant forces this to be 0. */
     208             :       /* 0x53 */ ushort parent_off;
     209             : 
     210             :       /* Bit field (MSB first)
     211             :          See FD_SHRED_DATA_FLAG_*
     212             : 
     213             :           [XX.. ....] Block complete?       0b00=no 0b01=no 0b11=yes (implies Entry batch complete)
     214             :           [.X.. ....] Entry batch complete?  0b0=no  0b1=yes
     215             :           [..XX XXXX] Reference tick number */
     216             :       /* 0x55 */ uchar  flags;
     217             : 
     218             :       /* Shred size: size of data shred headers (88 bytes) + payload length */
     219             :       /* 0x56 */ ushort size;
     220             :     } data;
     221             : 
     222             :     /* Common coding shred header */
     223             :     struct __attribute__((packed)) {
     224             :       /* Total number of data shreds in slot. Must be positive. */
     225             :       /* 0x53 */ ushort data_cnt;
     226             : 
     227             :       /* Total number of coding shreds in slot. Must be positive. */
     228             :       /* 0x55 */ ushort code_cnt;
     229             : 
     230             :       /* Index within the vector of coding shreds in slot. In [0,
     231             :          code_cnt).  Also, shred.code.idx <= shred.idx. */
     232             :       /* 0x57 */ ushort idx;
     233             :     } code;
     234             :   };
     235             : };
     236             : typedef struct fd_shred fd_shred_t;
     237             : 
     238             : FD_PROTOTYPES_BEGIN
     239             : 
     240             : /* fd_shred_parse: Parses and validates an untrusted shred stored in
     241             :    bytes buf[i] for i in [0, sz).  sz must be at least FD_SHRED_MIN_SZ
     242             :    bytes.  Allows trailing data.
     243             : 
     244             :    The returned pointer either equals the input pointer or is NULL if
     245             :    the given shred is malformed or violates any invariants described
     246             :    above. */
     247             : FD_FN_PURE fd_shred_t const *
     248             : fd_shred_parse( uchar const * buf,
     249             :                 ulong         sz );
     250             : 
     251             : /* fd_shred_type: Returns the value of the shred's type field. (FD_SHRED_TYPE_*) */
     252             : FD_FN_CONST static inline uchar
     253   308909103 : fd_shred_type( uchar variant ) {
     254   308909103 :   return variant & 0xf0;
     255   308909103 : }
     256             : 
     257             : /* fd_shred_variant: Returns the encoded variant field
     258             :    given the shred type and merkle proof length. */
     259             : FD_FN_CONST static inline uchar
     260             : fd_shred_variant( uchar type,
     261   101837526 :                   uchar merkle_cnt ) {
     262   101837526 :   if( FD_LIKELY( type==FD_SHRED_TYPE_LEGACY_DATA ) )
     263           3 :     merkle_cnt = 0x05;
     264   101837526 :   if( FD_LIKELY( type==FD_SHRED_TYPE_LEGACY_CODE ) )
     265           3 :     merkle_cnt = 0x0a;
     266   101837526 :   return (uchar)(type | merkle_cnt);
     267   101837526 : }
     268             : 
     269             : FD_FN_PURE static inline ulong
     270   101455980 : fd_shred_sz( fd_shred_t const * shred ) {
     271   101455980 :   uchar type = fd_shred_type( shred->variant );
     272   101455980 :   return fd_ulong_if(
     273   101455980 :     type & FD_SHRED_TYPEMASK_CODE,
     274   101455980 :     FD_SHRED_MAX_SZ,
     275   101455980 :     fd_ulong_if( type==FD_SHRED_TYPE_LEGACY_DATA, shred->data.size, FD_SHRED_MIN_SZ)
     276   101455980 :   ); /* Legacy data */
     277   101455980 : }
     278             : 
     279             : /* fd_shred_header_sz: Returns the header size of a shred.
     280             :    Returns zero if the shred has an invalid variant.
     281             : 
     282             :    Accesses offsets up to FD_SHRED_HEADER_MIN_SZ. */
     283             : FD_FN_CONST static inline ulong
     284        9909 : fd_shred_header_sz( uchar variant ) {
     285        9909 :   uchar type = fd_shred_type( variant );
     286        9909 :   if( FD_LIKELY( type & FD_SHRED_TYPEMASK_DATA ) )
     287        4524 :     return FD_SHRED_DATA_HEADER_SZ;
     288        5385 :   if( FD_LIKELY( type & FD_SHRED_TYPEMASK_CODE ) )
     289        5385 :     return FD_SHRED_CODE_HEADER_SZ;
     290           0 :   return 0;
     291        5385 : }
     292             : 
     293             : /* fd_shred_merkle_cnt: Returns number of nodes in the merkle inclusion
     294             :    proof.  Note that this excludes the root.  Returns zero if the given
     295             :    shred is not a merkle variant. */
     296             : FD_FN_CONST static inline uint
     297   101470254 : fd_shred_merkle_cnt( uchar variant ) {
     298   101470254 :   uchar type = fd_shred_type( variant );
     299   101470254 :   if( FD_UNLIKELY( ( type == FD_SHRED_TYPE_LEGACY_DATA ) | ( type == FD_SHRED_TYPE_LEGACY_CODE ) ) )
     300          45 :     return 0;
     301   101470209 :   return (variant&0xfU);
     302   101470254 : }
     303             : 
     304             : /* fd_shred_merkle_sz: Returns the size in bytes of the merkle inclusion proof.
     305             :    Returns zero if the given shred is not a merkle variant.  */
     306             : FD_FN_CONST static inline ulong
     307   101461065 : fd_shred_merkle_sz( uchar variant ) {
     308   101461065 :   return fd_shred_merkle_cnt( variant ) * FD_SHRED_MERKLE_NODE_SZ;
     309   101461065 : }
     310             : 
     311             : 
     312             : /* fd_shred_is_chained: Returns true if the shred is a chained merkle data or code shred. */
     313             : FD_FN_CONST static inline uchar
     314       18831 : fd_shred_is_chained( ulong type ) {
     315       18831 :   return (uchar)(
     316       18831 :          ( type == FD_SHRED_TYPE_MERKLE_DATA_CHAINED )
     317       18831 :        | ( type == FD_SHRED_TYPE_MERKLE_CODE_CHAINED )
     318       18831 :        | ( type == FD_SHRED_TYPE_MERKLE_DATA_CHAINED_RESIGNED )
     319       18831 :        | ( type == FD_SHRED_TYPE_MERKLE_CODE_CHAINED_RESIGNED ) );
     320       18831 : }
     321             : 
     322             : /* fd_shred_is_resigned: Returns true if the shred is resigned by the retransmitter */
     323             : FD_FN_CONST static inline uchar
     324   101464284 : fd_shred_is_resigned( ulong type ) {
     325   101464284 :   return ( type == FD_SHRED_TYPE_MERKLE_DATA_CHAINED_RESIGNED )
     326   101464284 :        | ( type == FD_SHRED_TYPE_MERKLE_CODE_CHAINED_RESIGNED );
     327   101464284 : }
     328             : 
     329             : /* fd_shred_is_{data,code} return 1 if the provided shred type is one of
     330             :    the data (or code, respectively) types, and 0 if not.  The value
     331             :    provided for type must be a valid shred type (one of the
     332             :    FD_SHRED_TYPE_* values).  For the purposes of these functions,
     333             :    properties beyond data/code are ignored; e.g. a chained resigned
     334             :    Merkle data shred is considered a data shred. */
     335        3522 : FD_FN_CONST static inline uchar fd_shred_is_data( ulong type ) { return (type & 0xC0UL)==0x80UL; }
     336         294 : FD_FN_CONST static inline uchar fd_shred_is_code( ulong type ) { return (type & 0xC0UL)==0x40UL; }
     337             : 
     338             : /* fd_shred_swap_type: changes data into code or vice versa without
     339             :    affecting leagacy, merkle, chained, or resigned status.  For example,
     340             :    fd_shred_swap_type( chained resigned data ) == chained resigned code.
     341             :    fd_shred_swap_type( merkle code ) == merkle data. */
     342             : FD_FN_CONST static inline uchar
     343        3057 : fd_shred_swap_type( ulong type ) {
     344             :   /* Swap bits 4 and 5. Swap bits 6 and 7. */
     345        3057 :   return (uchar)(((type & 0x50UL)<<1) | ((type&0xA0UL)>>1));
     346        3057 : }
     347             : 
     348             : /* fd_shred_payload_sz: Returns the payload size of a shred.
     349             :    Undefined behavior if the shred has not passed `fd_shred_parse`. */
     350             : FD_FN_PURE static inline ulong
     351         294 : fd_shred_payload_sz( fd_shred_t const * shred ) {
     352         294 :   ulong type = fd_shred_type( shred->variant );
     353         294 :   if( FD_LIKELY( type & FD_SHRED_TYPEMASK_DATA ) ) {
     354         147 :     return shred->data.size - FD_SHRED_DATA_HEADER_SZ;
     355         147 :   } else {
     356         147 :     return fd_shred_sz( shred ) - FD_SHRED_CODE_HEADER_SZ
     357         147 :       - fd_shred_merkle_sz( shred->variant )
     358         147 :       - fd_ulong_if( fd_shred_is_chained( type ), FD_SHRED_MERKLE_ROOT_SZ, 0 )
     359         147 :       - fd_ulong_if( fd_shred_is_resigned( type ), FD_SHRED_SIGNATURE_SZ, 0 );
     360         147 :   }
     361         294 : }
     362             : 
     363             : /* fd_shred_merkle_off: Returns the byte offset of the merkle inclusion proof of a shred.
     364             : 
     365             :    The provided shred must have passed validation in fd_shred_parse(). */
     366             : FD_FN_PURE static inline ulong
     367   101449563 : fd_shred_merkle_off( fd_shred_t const * shred ) {
     368   101449563 :   ulong type = fd_shred_type( shred->variant );
     369   101449563 :   return fd_shred_sz( shred )
     370   101449563 :     - fd_shred_merkle_sz( shred->variant )
     371   101449563 :     - fd_ulong_if( fd_shred_is_resigned( type ), FD_SHRED_SIGNATURE_SZ, 0 );
     372   101449563 : }
     373             : 
     374             : /* fd_shred_merkle_nodes: Returns a pointer to the shred's merkle proof data.
     375             : 
     376             :    The provided shred must have passed validation in fd_shred_parse(). */
     377             : FD_FN_PURE static inline fd_shred_merkle_t const *
     378        3009 : fd_shred_merkle_nodes( fd_shred_t const * shred ) {
     379        3009 :   uchar const * ptr = (uchar const *)shred;
     380        3009 :   ptr += fd_shred_merkle_off( shred );
     381        3009 :   return (fd_shred_merkle_t const *)ptr;
     382        3009 : }
     383             : 
     384             : /* fd_shred_data_payload: Returns a pointer to a data shred payload.
     385             : 
     386             :   The provided shred must have passed validation in fd_shred_parse(),
     387             :   and must satisfy `type&FD_SHRED_TYPEMASK_DATA`
     388             :   where `uchar type = fd_shred_type( shred->variant )`. */
     389             : FD_FN_CONST static inline uchar const *
     390           3 : fd_shred_data_payload( fd_shred_t const * shred ) {
     391           3 :   return (uchar const *)shred + FD_SHRED_DATA_HEADER_SZ;
     392           3 : }
     393             : 
     394             : /* fd_shred_code_payload: Returns a pointer to a coding shred payload.
     395             : 
     396             :   The provided shred must have passed validation in fd_shred_parse(),
     397             :   and must satisfy `type&FD_SHRED_TYPEMASK_CODE`
     398             :   where `uchar type = fd_shred_type( shred->variant )`. */
     399             : FD_FN_CONST static inline uchar const *
     400           0 : fd_shred_code_payload( fd_shred_t const * shred ) {
     401           0 :   return (uchar const *)shred + FD_SHRED_CODE_HEADER_SZ;
     402           0 : }
     403             : 
     404             : /* fd_shred_chain_offset: Assuming that `shred` is a chained Merkle
     405             :    variant, compute the offset from the start of the shred to the start
     406             :    of the chained Merkle root.  U.B. if the shred is not a chained
     407             :    variant. */
     408             : FD_FN_CONST static inline ulong
     409        1446 : fd_shred_chain_offset( uchar variant ) {
     410        1446 :   ulong type = fd_shred_type( variant );
     411        1446 :   return fd_ulong_if( type & FD_SHRED_TYPEMASK_CODE, FD_SHRED_MAX_SZ, FD_SHRED_MIN_SZ )
     412        1446 :     - FD_SHRED_MERKLE_ROOT_SZ
     413        1446 :     - fd_shred_merkle_sz( variant )
     414        1446 :     - fd_ulong_if( fd_shred_is_resigned( type ), FD_SHRED_SIGNATURE_SZ, 0 );
     415        1446 : }
     416             : 
     417             : /* fd_shred_retrasmitter_sig_off: Assuming that `shred` is a resigned
     418             :    variant, compute the offset from the start of the shred to the start
     419             :    of the retransmitter signature.  U.B if the shred is not a resigned
     420             :    chained type. */
     421             : FD_FN_PURE static inline ulong
     422         192 : fd_shred_retransmitter_sig_off( fd_shred_t const * shred ) {
     423         192 :   return fd_shred_sz( shred )-FD_SHRED_SIGNATURE_SZ;
     424         192 : }
     425             : 
     426             : FD_PROTOTYPES_END
     427             : 
     428             : #endif /* HEADER_fd_src_ballet_shred_fd_shred_h */