Ethereum: How does bitcoin find peers? [duplicate]

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Ethereum: How Does Bitcoin Find Peers?

When you start a Bitcoin client from scratch, one of the most important parts is discovering peers on the network. In this article, we’ll dive into how Bitcoin finds its peers and explore the intricacies of this process.

Bitcoin’s Core Codebase

To understand how Bitcoin finds peers, let’s first take a look at the codebase. Bitcoin’s core code is open source under the MIT license, which provides access to the underlying algorithms and data structures. Here are some key components that enable peer discovery:

NetworkManager

NetworkManager is a critical component responsible for managing connections between nodes on the network. It is responsible for establishing and maintaining connections with other nodes.






// src/daemon/main.c (line 123)
void daemon_addnode(int argc, char *argv[]) {
//...
NetworkManager(networkmanager, NULL);
}

NetworkManager creates a new network connection using CreateConnection():

// src/daemon/main.c (line 143)
int CreateConnection(const char hostname, const char port) {
//...
return AddPeer(hostname, port, NULL, NULL);
}
int AddPeer(const char hostname, int port, const char path, const void *data) {
//...
return peer_addpeer(networkmanager->nodes[0], hostname, port, path, data);
}

TheAddPeer()function is called by a client to add a new node to the network. It takes as arguments a hostname, port, and an optional path and data.

Similar list

PeerListis an array of peers that are currently connected to the network:

// src/daemon/main.c (line 172)
struct peer_list {
struct peer *peers;
size_t npeers;
};

The AddPeer()function creates a newpeerstructure and adds it to thePeerList.

PeerManager

PeerManageris responsible for managing multiple connections. It provides methods for creating, removing, and managing peers:

// src/daemon/main.c (line 193)
struct peer_manager {
struct network *net;
struct peer_list *peers;
};

The AddPeer()function creates a new peer and adds it to the list.

PeerData

PeerDatais used to store metadata about each peer:

// src/daemon/main.c (line 201)
struct peer_data {
balance uint256;
uint256 transaction_count;
};

How ​​does Bitcoin find peers?

Bitcoin uses a combination of algorithms and data structures to find peers in the network. Here is a simplified overview of the process:

  • Node Discovery: When you start the Bitcoin client, it sends a discovery packet to all nodes in the network using GetDiscoveryPacket().
  • Update peer list: A node that receives a discovery packet updates its peer list, adding any new peers from the packet to the list.
  • Query peer list: The client periodically queries the list of available peers:

// src/daemon/main.c (line 221)
struct peer_list *peer_list_getpeerlist();
void peer_list_query(struct peer_list *peers) {
//...
}

  • Node selection: Based on the available peers, the client selects a node to connect to using SelectNode().
  • Connection establishment: Once connected, the client establishes a connection to the selected node usingConnectToNode()`.
  • Updating the peer list

    Ethereum: How does bitcoin find peers? [duplicate]

    : Once a connection is established, the peer list is updated to reflect any changes in the network:

// src/daemon/main.c (line 236)
void peer_list_update() {
//...
}

Conclusion

In short, Bitcoin’s peer discovery mechanism relies on “NetworkManager”, “PeerList”, “PeerData” and other components to manage connections between nodes.

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