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 "../bmtree/fd_bmtree.h"
       5             : 
       6             : /* Shreds form the on-wire representation of Solana block data
       7             :    optimized for transmission over unreliable links/WAN.
       8             : 
       9             :    ### Layout
      10             : 
      11             :    Each shred is 1228 bytes long.
      12             : 
      13             :       +------------------------+
      14             :       | Common Shred Header    | 83 bytes
      15             :       +------------------------+
      16             :       | Data Header            | 5 bytes
      17             :       | or Coding Header       | or 6 bytes
      18             :       +------------------------+
      19             :       |                        | variable
      20             :       | Payload                | length
      21             :       |                        |
      22             :       +------------------------+
      23             : 
      24             :        for Merkle shreds, followed by:
      25             : 
      26             :       +------------------------+
      27             :       | (Chained merkle root)  | 32 bytes
      28             :       +------------------------+
      29             :       +------------------------+
      30             :       | Merkle node #0 (root)  | 20 bytes
      31             :       +------------------------+
      32             :       | Merkle node #1         | 20 bytes
      33             :       ..........................
      34             : 
      35             :        for resigned shreds shreds, followed by:
      36             : 
      37             :       +------------------------+
      38             :       | signature              | 64 bytes
      39             :       ..........................
      40             : 
      41             :    ### Shredding
      42             : 
      43             :    For a given input data blob (usually an entry batch),
      44             :    data shreds are derived by simply splitting up the blob into subslices.
      45             : 
      46             :    Each shred is sized such that it fits into a single UDP packet,
      47             :    i.e. currently bound by the generally accepted IPv6 MTU of 1280 bytes.
      48             : 
      49             :    ### Forward Error Correction
      50             : 
      51             :    Coding shreds implement Reed-Solomon error correction to provide tolerance against packet loss.
      52             : 
      53             :    Each data shred is first assigned an FEC set.
      54             :    For the vector of data shreds in each set, a corresponding vector of coding shreds contains parity data.
      55             : 
      56             :    FEC sets and entry batches do not necessarily align.
      57             : 
      58             :    ### Merkle Inclusion Proofs
      59             : 
      60             :    Data and coding shreds come in two variants respectively: legacy and merkle.
      61             :    Merkle shreds extend legacy shreds by adding FEC set inclusion proofs.
      62             : 
      63             :    It allows the block producer to commit to the vector of shreds that make up an FEC set.
      64             :    The inclusion proof is used to verify whether a shred is part of the FEC set commitment.
      65             : 
      66             :    The length of the inclusion proof is indicated by the variant field.
      67             : 
      68             :    ### resigned shreds
      69             : 
      70             :    Resigned shreds allow for an additional signature to be added on to lock down
      71             :    the retransmitter for turbine propagation
      72             : 
      73             :    ### Authentication
      74             : 
      75             :    Shreds are signed by the block producer.
      76             :    Consequentially, only the block producer is able to create valid shreds for any given block. */
      77             : 
      78             : #include "../fd_ballet.h"
      79             : 
      80             : /* FD_SHRED_MAX_SZ: The max byte size of a shred.
      81             :    This limit derives from the IPv6 MTU of 1280 bytes, minus 48 bytes
      82             :    for the UDP/IPv6 headers and another 4 bytes for good measure.  Most
      83             :    shreds are this size, but Merkle data shreds may be smaller. */
      84   102428826 : #define FD_SHRED_MAX_SZ (1228UL)
      85             : /* FD_SHRED_MIN_SZ: The minimum byte size of a shred.
      86             :    A code shred of the max size covers a data shred of the minimum size
      87             :    with no padding. */
      88   102427233 : #define FD_SHRED_MIN_SZ (1203UL)
      89             : /* FD_SHRED_DATA_HEADER_SZ: size of all headers for data type shreds. */
      90   100564068 : #define FD_SHRED_DATA_HEADER_SZ (0x58UL)
      91             : /* FD_SHRED_CODE_HEADER_SZ: size of all headers for coding type shreds. */
      92    51177402 : #define FD_SHRED_CODE_HEADER_SZ (0x59UL)
      93             : 
      94             : /* FD_SHRED_TYPE_* identifies the type of a shred.
      95             :    It is located at the four high bits of byte 0x40 (64) of the shred header
      96             :    and can be extracted using the fd_shred_type() function. */
      97             : /* FD_SHRED_TYPE_LEGACY_DATA: A shred carrying raw binary data. */
      98   105967074 : #define FD_SHRED_TYPE_LEGACY_DATA ((uchar)0xA0)
      99             : /* FD_SHRED_TYPE_LEGACY_CODE: A shred carrying Reed-Solomon ECC. */
     100             : #define FD_SHRED_TYPE_LEGACY_CODE ((uchar)0x50)
     101             : /* FD_SHRED_TYPE_MERKLE_DATA: A shred carrying raw binary data and a merkle inclusion proof. */
     102    54984906 : #define FD_SHRED_TYPE_MERKLE_DATA ((uchar)0x80)
     103             : /* FD_SHRED_TYPE_MERKLE_CODE: A shred carrying Reed-Solomon ECC and a merkle inclusion proof. */
     104   153215931 : #define FD_SHRED_TYPE_MERKLE_CODE ((uchar)0x40)
     105             : /* FD_SHRED_TYPE_MERKLE_DATA_CHAINED: A shred carrying raw binary data and a chained merkle inclusion proof. */
     106       23292 : #define FD_SHRED_TYPE_MERKLE_DATA_CHAINED ((uchar)0x90)
     107             : /* FD_SHRED_TYPE_MERKLE_CODE_CHAINED: A shred carrying Reed-Solomon ECC and a chained merkle inclusion proof. */
     108       22428 : #define FD_SHRED_TYPE_MERKLE_CODE_CHAINED ((uchar)0x60)
     109             : 
     110             : /* FD_SHRED_TYPE_MERKLE_DATA_CHAINED_RESIGNED: A shred carrying raw binary data and a chained merkle inclusion proof and resigned. */
     111   101486664 : #define FD_SHRED_TYPE_MERKLE_DATA_CHAINED_RESIGNED ((uchar)0xB0)
     112             : /* FD_SHRED_TYPE_MERKLE_CODE_CHAINED_RESIGNED: A shred carrying Reed-Solomon ECC and a chained merkle inclusion proof and resigned. */
     113   101485032 : #define FD_SHRED_TYPE_MERKLE_CODE_CHAINED_RESIGNED ((uchar)0x70)
     114             : 
     115             : /* FD_SHRED_TYPEMASK_DATA: bitwise AND with type matches data shred */
     116             : #define FD_SHRED_TYPEMASK_DATA FD_SHRED_TYPE_MERKLE_DATA
     117             : /* FD_SHRED_TYPEMASK_CODE: bitwise AND with type matches code shred */
     118   101457426 : #define FD_SHRED_TYPEMASK_CODE FD_SHRED_TYPE_MERKLE_CODE
     119             : 
     120             : /* FD_SHRED_MERKLE_ROOT_SZ: the size of a merkle tree root in bytes. */
     121       21945 : #define FD_SHRED_MERKLE_ROOT_SZ (32UL)
     122             : /* FD_SHRED_MERKLE_NODE_SZ: the size of a merkle inclusion proof node in bytes. */
     123   102946059 : #define FD_SHRED_MERKLE_NODE_SZ (20UL)
     124             : /* FD_SHRED_MERKLE_LAYER_CNT: the count of inclusion proof layers in the binary merkle tree. */
     125         159 : #define FD_SHRED_MERKLE_LAYER_CNT (10UL)
     126             : /* FD_SHRED_SIGNATURE_SZ: the size of a signature in a shred. */
     127   101467497 : #define FD_SHRED_SIGNATURE_SZ (64UL)
     128             : /* A merkle inclusion proof node. */
     129             : typedef uchar fd_shred_merkle_t[FD_SHRED_MERKLE_NODE_SZ];
     130             : 
     131             : /* Constants relating to the data shred "flags" field. */
     132             : 
     133             : /* Mask of the "reference tick"    field in shred.data.flags */
     134           0 : #define FD_SHRED_DATA_REF_TICK_MASK      ((uchar)0x3f)
     135             : /* Mask of the "slot complete"       bit in shred.data.flags
     136             :    Indicates the last shred in a slot. */
     137             : #define FD_SHRED_DATA_FLAG_SLOT_COMPLETE ((uchar)0x80)
     138             : /* Mask of the "data batch complete" bit in shred.data.flags */
     139             : #define FD_SHRED_DATA_FLAG_DATA_COMPLETE ((uchar)0x40)
     140             : 
     141             : /* Maximum number of data shreds in a slot, also maximum number of parity shreds in a slot */
     142           0 : #define FD_SHRED_MAX_PER_SLOT (1 << 15UL) /* 32,768 shreds */
     143             : 
     144             : /* Offset of the shred variant. Used for parsing. */
     145             : #define FD_SHRED_VARIANT_OFF 0x40
     146             : 
     147             : /* Firedancer-specific internal error codes.
     148             : 
     149             :    These are not part of the Solana protocol. */
     150             : 
     151           0 : #define FD_SHRED_EBATCH  0x4000 /* End of batch reached (success)
     152             :                                    no more shreds and found FD_SHRED_DATA_FLAG_DATA_COMPLETE */
     153           0 : #define FD_SHRED_ESLOT   0x8000 /* End of slot reached (success)
     154             :                                    no more shreds and found FD_SHRED_DATA_FLAG_SLOT_COMPLETE */
     155           0 : #define FD_SHRED_ENOMEM      12 /* Error: Target buffer too small */
     156           0 : #define FD_SHRED_EINVAL      22 /* Error: Invalid shred data */
     157           0 : #define FD_SHRED_EPIPE       32 /* Error: Expected data in source buffer, got EOF */
     158             : 
     159             : /* Primary shred data structure.
     160             :    Relies heavily on packed fields and unaligned memory accesses. */
     161             : struct __attribute__((packed)) fd_shred {
     162             :   /* Ed25519 signature over the shred
     163             : 
     164             :      For legacy type shreds, signs over content of the shred structure past this signature field.
     165             :      For merkle type shreds, signs over the first node of the inclusion proof (merkle root). */
     166             :   /* 0x00 */ fd_ed25519_sig_t signature;
     167             : 
     168             :   /* Shred variant specifier
     169             :      Consists of two four bit fields. (Deliberately not using bit fields here)
     170             : 
     171             :      The high four bits indicate the shred type:
     172             :      - 0101: legacy code
     173             :      - 1010: legacy data
     174             :      - 0100: merkle code
     175             :      - 0110: merkle code (chained)
     176             :      - 0111: merkle code (chained resigned)
     177             :      - 1000: merkle data
     178             :      - 1001: merkle data (chained)
     179             :      - 1011: merkle data (chained resigned)
     180             : 
     181             :      For legacy type shreds, the low four bits are set to static patterns.
     182             :      For merkle type shreds, the low four bits are set to the number of non-root nodes in the inclusion proof.
     183             :      For merkle code type shreds, the 3rd highest bit represents if the merkle tree is chained.
     184             :      For merkle data type shreds, the 4th highest bit represents if the merkle tree is chained.
     185             :      For merkle code type shreds, the 4th highest bit represents if the shred is resigned.
     186             :      For merkle data type shreds, the 3th highest bit represents if the shred is resigned.
     187             : */
     188             :   /* 0x40 */ uchar  variant;
     189             : 
     190             :   /* Slot number that this shred is part of */
     191             :   /* 0x41 */ ulong  slot;
     192             : 
     193             :   /* Index of this shred within the slot */
     194             :   /* 0x49 */ uint   idx;
     195             : 
     196             :   /* Hash of the genesis version and historical hard forks of the current chain */
     197             :   /* 0x4d */ ushort version;
     198             : 
     199             :   /* Index into the vector of FEC sets for this slot. For data shreds, fec_set_idx<=idx. */
     200             :   /* 0x4f */ uint   fec_set_idx;
     201             : 
     202             :   union {
     203             :     /* Common data shred header */
     204             :     struct __attribute__((packed)) fd_shred_data {
     205             :       /* Slot number difference between this block and the parent block.
     206             :          parent_off <= slot.
     207             :          Always greater than zero, except for slot 0, in which case the
     208             :          previous invariant forces this to be 0. */
     209             :       /* 0x53 */ ushort parent_off;
     210             : 
     211             :       /* Bit field (MSB first)
     212             :          See FD_SHRED_DATA_FLAG_*
     213             : 
     214             :           [XX.. ....] Block complete?       0b00=no 0b01=no 0b11=yes (implies Entry batch complete)
     215             :           [.X.. ....] Entry batch complete?  0b0=no  0b1=yes
     216             :           [..XX XXXX] Reference tick number */
     217             :       /* 0x55 */ uchar  flags;
     218             : 
     219             :       /* Shred size: size of data shred headers (88 bytes) + payload length */
     220             :       /* 0x56 */ ushort size;
     221             :     } data;
     222             : 
     223             :     /* Common coding shred header */
     224             :     struct __attribute__((packed)) fd_shred_code {
     225             :       /* Total number of data shreds in slot. Must be positive. */
     226             :       /* 0x53 */ ushort data_cnt;
     227             : 
     228             :       /* Total number of coding shreds in slot. Must be positive. */
     229             :       /* 0x55 */ ushort code_cnt;
     230             : 
     231             :       /* Index within the vector of coding shreds in slot. In [0,
     232             :          code_cnt).  Also, shred.code.idx <= shred.idx. */
     233             :       /* 0x57 */ ushort idx;
     234             :     } code;
     235             :   };
     236             : };
     237             : typedef struct fd_shred_data fd_shred_data_t;
     238             : typedef struct fd_shred_code fd_shred_code_t;
     239             : typedef struct fd_shred fd_shred_t;
     240             : 
     241             : FD_PROTOTYPES_BEGIN
     242             : 
     243             : /* fd_shred_parse: Parses and validates an untrusted shred stored in
     244             :    bytes buf[i] for i in [0, sz).  sz must be at least FD_SHRED_MIN_SZ
     245             :    bytes.  Allows trailing data.
     246             : 
     247             :    The returned pointer either equals the input pointer or is NULL if
     248             :    the given shred is malformed or violates any invariants described
     249             :    above. */
     250             : FD_FN_PURE fd_shred_t const *
     251             : fd_shred_parse( uchar const * buf,
     252             :                 ulong         sz );
     253             : 
     254             : /* fd_shred_type: Returns the value of the shred's type field. (FD_SHRED_TYPE_*) */
     255             : FD_FN_CONST static inline uchar
     256   308909103 : fd_shred_type( uchar variant ) {
     257   308909103 :   return variant & 0xf0;
     258   308909103 : }
     259             : 
     260             : /* fd_shred_variant: Returns the encoded variant field
     261             :    given the shred type and merkle proof length. */
     262             : FD_FN_CONST static inline uchar
     263             : fd_shred_variant( uchar type,
     264   101837526 :                   uchar merkle_cnt ) {
     265   101837526 :   if( FD_LIKELY( type==FD_SHRED_TYPE_LEGACY_DATA ) )
     266           3 :     merkle_cnt = 0x05;
     267   101837526 :   if( FD_LIKELY( type==FD_SHRED_TYPE_LEGACY_CODE ) )
     268           3 :     merkle_cnt = 0x0a;
     269   101837526 :   return (uchar)(type | merkle_cnt);
     270   101837526 : }
     271             : 
     272             : FD_FN_PURE static inline ulong
     273   101455980 : fd_shred_sz( fd_shred_t const * shred ) {
     274   101455980 :   uchar type = fd_shred_type( shred->variant );
     275   101455980 :   return fd_ulong_if(
     276   101455980 :     type & FD_SHRED_TYPEMASK_CODE,
     277   101455980 :     FD_SHRED_MAX_SZ,
     278   101455980 :     fd_ulong_if( type==FD_SHRED_TYPE_LEGACY_DATA, shred->data.size, FD_SHRED_MIN_SZ)
     279   101455980 :   ); /* Legacy data */
     280   101455980 : }
     281             : 
     282             : /* fd_shred_header_sz: Returns the header size of a shred.
     283             :    Returns zero if the shred has an invalid variant.
     284             : 
     285             :    Accesses offsets up to FD_SHRED_HEADER_MIN_SZ. */
     286             : FD_FN_CONST static inline ulong
     287        9909 : fd_shred_header_sz( uchar variant ) {
     288        9909 :   uchar type = fd_shred_type( variant );
     289        9909 :   if( FD_LIKELY( type & FD_SHRED_TYPEMASK_DATA ) )
     290        4524 :     return FD_SHRED_DATA_HEADER_SZ;
     291        5385 :   if( FD_LIKELY( type & FD_SHRED_TYPEMASK_CODE ) )
     292        5385 :     return FD_SHRED_CODE_HEADER_SZ;
     293           0 :   return 0;
     294        5385 : }
     295             : 
     296             : /* fd_shred_merkle_cnt: Returns number of nodes in the merkle inclusion
     297             :    proof.  Note that this excludes the root.  Returns zero if the given
     298             :    shred is not a merkle variant. */
     299             : FD_FN_CONST static inline uint
     300   101470254 : fd_shred_merkle_cnt( uchar variant ) {
     301   101470254 :   uchar type = fd_shred_type( variant );
     302   101470254 :   if( FD_UNLIKELY( ( type == FD_SHRED_TYPE_LEGACY_DATA ) | ( type == FD_SHRED_TYPE_LEGACY_CODE ) ) )
     303          45 :     return 0;
     304   101470209 :   return (variant&0xfU);
     305   101470254 : }
     306             : 
     307             : /* fd_shred_merkle_sz: Returns the size in bytes of the merkle inclusion proof.
     308             :    Returns zero if the given shred is not a merkle variant.  */
     309             : FD_FN_CONST static inline ulong
     310   101461065 : fd_shred_merkle_sz( uchar variant ) {
     311   101461065 :   return fd_shred_merkle_cnt( variant ) * FD_SHRED_MERKLE_NODE_SZ;
     312   101461065 : }
     313             : 
     314             : 
     315             : /* fd_shred_is_chained: Returns true if the shred is a chained merkle data or code shred. */
     316             : FD_FN_CONST static inline uchar
     317       18831 : fd_shred_is_chained( ulong type ) {
     318       18831 :   return (uchar)(
     319       18831 :          ( type == FD_SHRED_TYPE_MERKLE_DATA_CHAINED )
     320       18831 :        | ( type == FD_SHRED_TYPE_MERKLE_CODE_CHAINED )
     321       18831 :        | ( type == FD_SHRED_TYPE_MERKLE_DATA_CHAINED_RESIGNED )
     322       18831 :        | ( type == FD_SHRED_TYPE_MERKLE_CODE_CHAINED_RESIGNED ) );
     323       18831 : }
     324             : 
     325             : /* fd_shred_is_resigned: Returns true if the shred is resigned by the retransmitter */
     326             : FD_FN_CONST static inline uchar
     327   101464284 : fd_shred_is_resigned( ulong type ) {
     328   101464284 :   return ( type == FD_SHRED_TYPE_MERKLE_DATA_CHAINED_RESIGNED )
     329   101464284 :        | ( type == FD_SHRED_TYPE_MERKLE_CODE_CHAINED_RESIGNED );
     330   101464284 : }
     331             : 
     332             : /* fd_shred_is_{data,code} return 1 if the provided shred type is one of
     333             :    the data (or code, respectively) types, and 0 if not.  The value
     334             :    provided for type must be a valid shred type (one of the
     335             :    FD_SHRED_TYPE_* values).  For the purposes of these functions,
     336             :    properties beyond data/code are ignored; e.g. a chained resigned
     337             :    Merkle data shred is considered a data shred. */
     338        3522 : FD_FN_CONST static inline uchar fd_shred_is_data( ulong type ) { return (type & 0xC0UL)==0x80UL; }
     339         294 : FD_FN_CONST static inline uchar fd_shred_is_code( ulong type ) { return (type & 0xC0UL)==0x40UL; }
     340             : 
     341             : /* fd_shred_swap_type: changes data into code or vice versa without
     342             :    affecting leagacy, merkle, chained, or resigned status.  For example,
     343             :    fd_shred_swap_type( chained resigned data ) == chained resigned code.
     344             :    fd_shred_swap_type( merkle code ) == merkle data. */
     345             : FD_FN_CONST static inline uchar
     346        3057 : fd_shred_swap_type( ulong type ) {
     347             :   /* Swap bits 4 and 5. Swap bits 6 and 7. */
     348        3057 :   return (uchar)(((type & 0x50UL)<<1) | ((type&0xA0UL)>>1));
     349        3057 : }
     350             : 
     351             : /* fd_shred_payload_sz: Returns the payload size of a shred.
     352             :    Undefined behavior if the shred has not passed `fd_shred_parse`. */
     353             : FD_FN_PURE static inline ulong
     354         294 : fd_shred_payload_sz( fd_shred_t const * shred ) {
     355         294 :   ulong type = fd_shred_type( shred->variant );
     356         294 :   if( FD_LIKELY( type & FD_SHRED_TYPEMASK_DATA ) ) {
     357         147 :     return shred->data.size - FD_SHRED_DATA_HEADER_SZ;
     358         147 :   } else {
     359         147 :     return fd_shred_sz( shred ) - FD_SHRED_CODE_HEADER_SZ
     360         147 :       - fd_shred_merkle_sz( shred->variant )
     361         147 :       - fd_ulong_if( fd_shred_is_chained( type ), FD_SHRED_MERKLE_ROOT_SZ, 0 )
     362         147 :       - fd_ulong_if( fd_shred_is_resigned( type ), FD_SHRED_SIGNATURE_SZ, 0 );
     363         147 :   }
     364         294 : }
     365             : 
     366             : /* fd_shred_merkle_off: Returns the byte offset of the merkle inclusion proof of a shred.
     367             : 
     368             :    The provided shred must have passed validation in fd_shred_parse(). */
     369             : FD_FN_PURE static inline ulong
     370   101449563 : fd_shred_merkle_off( fd_shred_t const * shred ) {
     371   101449563 :   ulong type = fd_shred_type( shred->variant );
     372   101449563 :   return fd_shred_sz( shred )
     373   101449563 :     - fd_shred_merkle_sz( shred->variant )
     374   101449563 :     - fd_ulong_if( fd_shred_is_resigned( type ), FD_SHRED_SIGNATURE_SZ, 0 );
     375   101449563 : }
     376             : 
     377             : /* fd_shred_merkle_nodes: Returns a pointer to the shred's merkle proof data.
     378             : 
     379             :    The provided shred must have passed validation in fd_shred_parse(). */
     380             : FD_FN_PURE static inline fd_shred_merkle_t const *
     381        3009 : fd_shred_merkle_nodes( fd_shred_t const * shred ) {
     382        3009 :   uchar const * ptr = (uchar const *)shred;
     383        3009 :   ptr += fd_shred_merkle_off( shred );
     384        3009 :   return (fd_shred_merkle_t const *)ptr;
     385        3009 : }
     386             : 
     387             : /* fd_shred_merkle_root: Assuming that `shred` is a Merkle variant,
     388             :    reconstructs the merkle root from a shred and populates it in
     389             :    root_out.  Returns 1 on success, 0 on failure.  The output value must
     390             :    be ignored if a failure is returned.  U.B. if the shred is not a
     391             :    merkle variant. */
     392             : FD_FN_PURE int
     393             : fd_shred_merkle_root( fd_shred_t const * shred, void * bmtree_mem, fd_bmtree_node_t * root_out );
     394             : 
     395             : /* fd_shred_data_payload: Returns a pointer to a data shred payload.
     396             : 
     397             :   The provided shred must have passed validation in fd_shred_parse(),
     398             :   and must satisfy `type&FD_SHRED_TYPEMASK_DATA`
     399             :   where `uchar type = fd_shred_type( shred->variant )`. */
     400             : FD_FN_CONST static inline uchar const *
     401           3 : fd_shred_data_payload( fd_shred_t const * shred ) {
     402           3 :   return (uchar const *)shred + FD_SHRED_DATA_HEADER_SZ;
     403           3 : }
     404             : 
     405             : /* fd_shred_code_payload: Returns a pointer to a coding shred payload.
     406             : 
     407             :   The provided shred must have passed validation in fd_shred_parse(),
     408             :   and must satisfy `type&FD_SHRED_TYPEMASK_CODE`
     409             :   where `uchar type = fd_shred_type( shred->variant )`. */
     410             : FD_FN_CONST static inline uchar const *
     411           0 : fd_shred_code_payload( fd_shred_t const * shred ) {
     412           0 :   return (uchar const *)shred + FD_SHRED_CODE_HEADER_SZ;
     413           0 : }
     414             : 
     415             : /* fd_shred_chain_offset: Assuming that `shred` is a chained Merkle
     416             :    variant, compute the offset from the start of the shred to the start
     417             :    of the chained Merkle root.  U.B. if the shred is not a chained
     418             :    variant. */
     419             : FD_FN_CONST static inline ulong
     420        1446 : fd_shred_chain_off( uchar variant ) {
     421        1446 :   ulong type = fd_shred_type( variant );
     422        1446 :   return fd_ulong_if( type & FD_SHRED_TYPEMASK_CODE, FD_SHRED_MAX_SZ, FD_SHRED_MIN_SZ )
     423        1446 :     - FD_SHRED_MERKLE_ROOT_SZ
     424        1446 :     - fd_shred_merkle_sz( variant )
     425        1446 :     - fd_ulong_if( fd_shred_is_resigned( type ), FD_SHRED_SIGNATURE_SZ, 0 );
     426        1446 : }
     427             : 
     428             : /* fd_shred_retrasmitter_sig_off: Assuming that `shred` is a resigned
     429             :    variant, compute the offset from the start of the shred to the start
     430             :    of the retransmitter signature.  U.B if the shred is not a resigned
     431             :    chained type. */
     432             : FD_FN_PURE static inline ulong
     433         192 : fd_shred_retransmitter_sig_off( fd_shred_t const * shred ) {
     434         192 :   return fd_shred_sz( shred )-FD_SHRED_SIGNATURE_SZ;
     435         192 : }
     436             : 
     437             : FD_PROTOTYPES_END
     438             : 
     439             : #endif /* HEADER_fd_src_ballet_shred_fd_shred_h */