github.com/btcsuite/btcd@v0.24.0/wire/invvect.go (about)

     1  // Copyright (c) 2013-2016 The btcsuite developers
     2  // Use of this source code is governed by an ISC
     3  // license that can be found in the LICENSE file.
     4  
     5  package wire
     6  
     7  import (
     8  	"fmt"
     9  	"io"
    10  
    11  	"github.com/btcsuite/btcd/chaincfg/chainhash"
    12  )
    13  
    14  const (
    15  	// MaxInvPerMsg is the maximum number of inventory vectors that can be in a
    16  	// single bitcoin inv message.
    17  	MaxInvPerMsg = 50000
    18  
    19  	// Maximum payload size for an inventory vector.
    20  	maxInvVectPayload = 4 + chainhash.HashSize
    21  
    22  	// InvWitnessFlag denotes that the inventory vector type is requesting,
    23  	// or sending a version which includes witness data.
    24  	InvWitnessFlag = 1 << 30
    25  )
    26  
    27  // InvType represents the allowed types of inventory vectors.  See InvVect.
    28  type InvType uint32
    29  
    30  // These constants define the various supported inventory vector types.
    31  const (
    32  	InvTypeError                InvType = 0
    33  	InvTypeTx                   InvType = 1
    34  	InvTypeBlock                InvType = 2
    35  	InvTypeFilteredBlock        InvType = 3
    36  	InvTypeWitnessBlock         InvType = InvTypeBlock | InvWitnessFlag
    37  	InvTypeWitnessTx            InvType = InvTypeTx | InvWitnessFlag
    38  	InvTypeFilteredWitnessBlock InvType = InvTypeFilteredBlock | InvWitnessFlag
    39  )
    40  
    41  // Map of service flags back to their constant names for pretty printing.
    42  var ivStrings = map[InvType]string{
    43  	InvTypeError:                "ERROR",
    44  	InvTypeTx:                   "MSG_TX",
    45  	InvTypeBlock:                "MSG_BLOCK",
    46  	InvTypeFilteredBlock:        "MSG_FILTERED_BLOCK",
    47  	InvTypeWitnessBlock:         "MSG_WITNESS_BLOCK",
    48  	InvTypeWitnessTx:            "MSG_WITNESS_TX",
    49  	InvTypeFilteredWitnessBlock: "MSG_FILTERED_WITNESS_BLOCK",
    50  }
    51  
    52  // String returns the InvType in human-readable form.
    53  func (invtype InvType) String() string {
    54  	if s, ok := ivStrings[invtype]; ok {
    55  		return s
    56  	}
    57  
    58  	return fmt.Sprintf("Unknown InvType (%d)", uint32(invtype))
    59  }
    60  
    61  // InvVect defines a bitcoin inventory vector which is used to describe data,
    62  // as specified by the Type field, that a peer wants, has, or does not have to
    63  // another peer.
    64  type InvVect struct {
    65  	Type InvType        // Type of data
    66  	Hash chainhash.Hash // Hash of the data
    67  }
    68  
    69  // NewInvVect returns a new InvVect using the provided type and hash.
    70  func NewInvVect(typ InvType, hash *chainhash.Hash) *InvVect {
    71  	return &InvVect{
    72  		Type: typ,
    73  		Hash: *hash,
    74  	}
    75  }
    76  
    77  // readInvVectBuf reads an encoded InvVect from r depending on the protocol
    78  // version.
    79  //
    80  // If b is non-nil, the provided buffer will be used for serializing small
    81  // values.  Otherwise a buffer will be drawn from the binarySerializer's pool
    82  // and return when the method finishes.
    83  //
    84  // NOTE: b MUST either be nil or at least an 8-byte slice.
    85  func readInvVectBuf(r io.Reader, pver uint32, iv *InvVect, buf []byte) error {
    86  	if _, err := io.ReadFull(r, buf[:4]); err != nil {
    87  		return err
    88  	}
    89  	iv.Type = InvType(littleEndian.Uint32(buf[:4]))
    90  
    91  	_, err := io.ReadFull(r, iv.Hash[:])
    92  	return err
    93  }
    94  
    95  // writeInvVectBuf serializes an InvVect to w depending on the protocol version.
    96  //
    97  // If b is non-nil, the provided buffer will be used for serializing small
    98  // values.  Otherwise a buffer will be drawn from the binarySerializer's pool
    99  // and return when the method finishes.
   100  //
   101  // NOTE: b MUST either be nil or at least an 8-byte slice.
   102  func writeInvVectBuf(w io.Writer, pver uint32, iv *InvVect, buf []byte) error {
   103  	littleEndian.PutUint32(buf[:4], uint32(iv.Type))
   104  	if _, err := w.Write(buf[:4]); err != nil {
   105  		return err
   106  	}
   107  
   108  	_, err := w.Write(iv.Hash[:])
   109  	return err
   110  }