github.com/sberex/go-sberex@v1.8.2-0.20181113200658-ed96ac38f7d7/whisper/whisperv6/doc.go (about)

     1  // This file is part of the go-sberex library. The go-sberex library is 
     2  // free software: you can redistribute it and/or modify it under the terms 
     3  // of the GNU Lesser General Public License as published by the Free 
     4  // Software Foundation, either version 3 of the License, or (at your option)
     5  // any later version.
     6  //
     7  // The go-sberex library is distributed in the hope that it will be useful, 
     8  // but WITHOUT ANY WARRANTY; without even the implied warranty of
     9  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser 
    10  // General Public License <http://www.gnu.org/licenses/> for more details.
    11  
    12  /*
    13  Package whisper implements the Whisper protocol (version 6).
    14  
    15  Whisper combines aspects of both DHTs and datagram messaging systems (e.g. UDP).
    16  As such it may be likened and compared to both, not dissimilar to the
    17  matter/energy duality (apologies to physicists for the blatant abuse of a
    18  fundamental and beautiful natural principle).
    19  
    20  Whisper is a pure identity-based messaging system. Whisper provides a low-level
    21  (non-application-specific) but easily-accessible API without being based upon
    22  or prejudiced by the low-level hardware attributes and characteristics,
    23  particularly the notion of singular endpoints.
    24  */
    25  
    26  // Contains the Whisper protocol constant definitions
    27  
    28  package whisperv6
    29  
    30  import (
    31  	"fmt"
    32  	"time"
    33  )
    34  
    35  // Whisper protocol parameters
    36  const (
    37  	ProtocolVersion    = uint64(6) // Protocol version number
    38  	ProtocolVersionStr = "6.0"     // The same, as a string
    39  	ProtocolName       = "shh"     // Nickname of the protocol in geth
    40  
    41  	// whisper protocol message codes, according to EIP-627
    42  	statusCode           = 0   // used by whisper protocol
    43  	messagesCode         = 1   // normal whisper message
    44  	powRequirementCode   = 2   // PoW requirement
    45  	bloomFilterExCode    = 3   // bloom filter exchange
    46  	p2pRequestCode       = 126 // peer-to-peer message, used by Dapp protocol
    47  	p2pMessageCode       = 127 // peer-to-peer message (to be consumed by the peer, but not forwarded any further)
    48  	NumberOfMessageCodes = 128
    49  
    50  	SizeMask      = byte(3) // mask used to extract the size of payload size field from the flags
    51  	signatureFlag = byte(4)
    52  
    53  	TopicLength     = 4  // in bytes
    54  	signatureLength = 65 // in bytes
    55  	aesKeyLength    = 32 // in bytes
    56  	aesNonceLength  = 12 // in bytes; for more info please see cipher.gcmStandardNonceSize & aesgcm.NonceSize()
    57  	keyIDSize       = 32 // in bytes
    58  	bloomFilterSize = 64 // in bytes
    59  	flagsLength     = 1
    60  
    61  	EnvelopeHeaderLength = 20
    62  
    63  	MaxMessageSize        = uint32(10 * 1024 * 1024) // maximum accepted size of a message.
    64  	DefaultMaxMessageSize = uint32(1024 * 1024)
    65  	DefaultMinimumPoW     = 0.2
    66  
    67  	padSizeLimit      = 256 // just an arbitrary number, could be changed without breaking the protocol
    68  	messageQueueLimit = 1024
    69  
    70  	expirationCycle   = time.Second
    71  	transmissionCycle = 300 * time.Millisecond
    72  
    73  	DefaultTTL           = 50 // seconds
    74  	DefaultSyncAllowance = 10 // seconds
    75  )
    76  
    77  type unknownVersionError uint64
    78  
    79  func (e unknownVersionError) Error() string {
    80  	return fmt.Sprintf("invalid envelope version %d", uint64(e))
    81  }
    82  
    83  // MailServer represents a mail server, capable of
    84  // archiving the old messages for subsequent delivery
    85  // to the peers. Any implementation must ensure that both
    86  // functions are thread-safe. Also, they must return ASAP.
    87  // DeliverMail should use directMessagesCode for delivery,
    88  // in order to bypass the expiry checks.
    89  type MailServer interface {
    90  	Archive(env *Envelope)
    91  	DeliverMail(whisperPeer *Peer, request *Envelope)
    92  }