github.com/ethereum/go-ethereum@v1.16.1/p2p/protocol.go (about)

     1  // Copyright 2014 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package p2p
    18  
    19  import (
    20  	"cmp"
    21  	"fmt"
    22  	"strings"
    23  
    24  	"github.com/ethereum/go-ethereum/p2p/enode"
    25  	"github.com/ethereum/go-ethereum/p2p/enr"
    26  )
    27  
    28  // Protocol represents a P2P subprotocol implementation.
    29  type Protocol struct {
    30  	// Name should contain the official protocol name,
    31  	// often a three-letter word.
    32  	Name string
    33  
    34  	// Version should contain the version number of the protocol.
    35  	Version uint
    36  
    37  	// Length should contain the number of message codes used
    38  	// by the protocol.
    39  	Length uint64
    40  
    41  	// Run is called in a new goroutine when the protocol has been
    42  	// negotiated with a peer. It should read and write messages from
    43  	// rw. The Payload for each message must be fully consumed.
    44  	//
    45  	// The peer connection is closed when Start returns. It should return
    46  	// any protocol-level error (such as an I/O error) that is
    47  	// encountered.
    48  	Run func(peer *Peer, rw MsgReadWriter) error
    49  
    50  	// NodeInfo is an optional helper method to retrieve protocol specific metadata
    51  	// about the host node.
    52  	NodeInfo func() interface{}
    53  
    54  	// PeerInfo is an optional helper method to retrieve protocol specific metadata
    55  	// about a certain peer in the network. If an info retrieval function is set,
    56  	// but returns nil, it is assumed that the protocol handshake is still running.
    57  	PeerInfo func(id enode.ID) interface{}
    58  
    59  	// DialCandidates, if non-nil, is a way to tell Server about protocol-specific nodes
    60  	// that should be dialed. The server continuously reads nodes from the iterator and
    61  	// attempts to create connections to them.
    62  	DialCandidates enode.Iterator
    63  
    64  	// Attributes contains protocol specific information for the node record.
    65  	Attributes []enr.Entry
    66  }
    67  
    68  func (p Protocol) cap() Cap {
    69  	return Cap{p.Name, p.Version}
    70  }
    71  
    72  // Cap is the structure of a peer capability.
    73  type Cap struct {
    74  	Name    string
    75  	Version uint
    76  }
    77  
    78  func (cap Cap) String() string {
    79  	return fmt.Sprintf("%s/%d", cap.Name, cap.Version)
    80  }
    81  
    82  // Cmp defines the canonical sorting order of capabilities.
    83  func (cap Cap) Cmp(other Cap) int {
    84  	if cap.Name == other.Name {
    85  		return cmp.Compare(cap.Version, other.Version)
    86  	}
    87  	return strings.Compare(cap.Name, other.Name)
    88  }