github.com/btcsuite/btcd@v0.24.0/addrmgr/doc.go (about)

     1  // Copyright (c) 2014 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  /*
     6  Package addrmgr implements concurrency safe Bitcoin address manager.
     7  
     8  # Address Manager Overview
     9  
    10  In order maintain the peer-to-peer Bitcoin network, there needs to be a source
    11  of addresses to connect to as nodes come and go.  The Bitcoin protocol provides
    12  the getaddr and addr messages to allow peers to communicate known addresses with
    13  each other.  However, there needs to a mechanism to store those results and
    14  select peers from them.  It is also important to note that remote peers can't
    15  be trusted to send valid peers nor attempt to provide you with only peers they
    16  control with malicious intent.
    17  
    18  With that in mind, this package provides a concurrency safe address manager for
    19  caching and selecting peers in a non-deterministic manner.  The general idea is
    20  the caller adds addresses to the address manager and notifies it when addresses
    21  are connected, known good, and attempted.  The caller also requests addresses as
    22  it needs them.
    23  
    24  The address manager internally segregates the addresses into groups and
    25  non-deterministically selects groups in a cryptographically random manner.  This
    26  reduce the chances multiple addresses from the same nets are selected which
    27  generally helps provide greater peer diversity, and perhaps more importantly,
    28  drastically reduces the chances an attacker is able to coerce your peer into
    29  only connecting to nodes they control.
    30  
    31  The address manager also understands routability and Tor addresses and tries
    32  hard to only return routable addresses.  In addition, it uses the information
    33  provided by the caller about connected, known good, and attempted addresses to
    34  periodically purge peers which no longer appear to be good peers as well as
    35  bias the selection toward known good peers.  The general idea is to make a best
    36  effort at only providing usable addresses.
    37  */
    38  package addrmgr