teems/App/net.cpp

#include <iostream>

#include "config.hpp"
#include "net.hpp"

NetIO::NetIO(boost::asio::io_context &io_context, const Config &config)
    : conf(config), myconf(config.nodes[config.my_node_num])
{
    num_nodes = conf.nodes.size();
    nodesockets.resize(num_nodes);
    me = conf.my_node_num;

    // Node number n will accept connections from nodes 0, ..., n-1 and
    // make connections to nodes n+1, ..., num_nodes-1.  This is all
    // single threaded, but it doesn't deadlock because node 0 isn't
    // waiting for any incoming connections, so it immediately makes
    // outgoing connections.  When it connects to node 1, that node
    // accepts its (only) incoming connection, and then starts making
    // its outgoing connections, etc.

    tcp::resolver resolver(io_context);
    tcp::acceptor acceptor(io_context,
        resolver.resolve(myconf.listenhost, myconf.listenport)->endpoint());

    for(size_t i=0; i<me; ++i) {
#ifdef VERBOSE_NET
        std::cerr << "Accepting number " << i << "\n";
#endif
        tcp::socket nodesock = acceptor.accept();
#ifdef VERBOSE_NET
        std::cerr << "Accepted number " << i << "\n";
#endif
        // Read 2 bytes from the socket, which will be the
        // connecting node's node number
        unsigned short node_num;
        boost::asio::read(nodesock,
            boost::asio::buffer(&node_num, sizeof(node_num)));
        if (node_num >= num_nodes) {
            std::cerr << "Received bad node number\n";
        } else {
            nodesockets[node_num] = std::move(nodesock);
#ifdef VERBOSE_NET
            std::cerr << "Received connection from " <<
                config.nodes[node_num].name << "\n";
#endif
        }
    }

    for(size_t i=me+1; i<num_nodes; ++i) {
        boost::system::error_code err;
        tcp::socket nodesock(io_context);
        while(1) {
#ifdef VERBOSE_NET
            std::cerr << "Connecting to " << config.nodes[i].name << "...\n";
#endif
            boost::asio::connect(nodesock,
                resolver.resolve(config.nodes[i].listenhost,
                    config.nodes[i].listenport), err);
            if (!err) break;
            std::cerr << "Connection to " << config.nodes[i].name <<
                " refused, will retry.\n";
            sleep(1);
        }
        // Write 2 bytes to the socket to tell the peer node our node
        // number
        unsigned short node_num = (unsigned short)me;
        boost::asio::write(nodesock,
            boost::asio::buffer(&node_num, sizeof(node_num)));
        nodesockets[i] = std::move(nodesock);
#ifdef VERBOSE_NET
        std::cerr << "Connected to " << config.nodes[i].name << "\n";
#endif
    }
}