scylladb/net/ip.cc

/*
 * Copyright (C) 2014 Cloudius Systems, Ltd.
 *
 */

#include "ip.hh"
#include "core/print.hh"
#include "core/future-util.hh"
#include "core/shared_ptr.hh"

namespace net {

std::ostream& operator<<(std::ostream& os, ipv4_address a) {
    auto ip = a.ip;
    return fprint(os, "%d.%d.%d.%d",
            (ip >> 24) & 0xff,
            (ip >> 16) & 0xff,
            (ip >> 8) & 0xff,
            (ip >> 0) & 0xff);
}

ipv4::ipv4(interface* netif)
    : _netif(netif)
    , _global_arp(netif)
    , _arp(_global_arp)
    , _l3(netif, eth_protocol_num::ipv4)
    , _rx_packets(_l3.receive([this] (packet p, ethernet_address ea) {
        return handle_received_packet(std::move(p), ea); },
      [this] (packet& p, size_t off) {
        return handle_on_cpu(p, off);}))
    , _tcp(*this)
    , _icmp(*this)
    , _l4({ { uint8_t(ip_protocol_num::tcp), &_tcp }, { uint8_t(ip_protocol_num::icmp), &_icmp }}) {
}

unsigned ipv4::handle_on_cpu(packet& p, size_t off)
{
    auto iph = p.get_header<ip_hdr>(off);

    if (_packet_filter) {
        bool h = false;
        auto r = _packet_filter->forward(p, off + sizeof(ip_hdr), iph->src_ip, iph->dst_ip, h);
        if (h) {
            return r;
        }
    }

    auto l4 = _l4[iph->ip_proto];
    if (!l4) {
        return engine.cpu_id();
    }
    return l4->forward(p, off + sizeof(ip_hdr), iph->src_ip, iph->dst_ip);
}

bool ipv4::in_my_netmask(ipv4_address a) const {
    return !((a.ip ^ _host_address.ip) & _netmask.ip);
}

bool ipv4::needs_frag(packet& p, ip_protocol_num prot_num, net::hw_features hw_features) {
    if (p.len() + ipv4_hdr_len_min <= hw_features.mtu) {
        return false;
    }

    if ((prot_num == ip_protocol_num::tcp && hw_features.tx_tso) ||
        (prot_num == ip_protocol_num::udp && hw_features.tx_ufo)) {
        return false;
    }

    return true;
}

future<>
ipv4::handle_received_packet(packet p, ethernet_address from) {
    auto iph = p.get_header<ip_hdr>(0);
    if (!iph) {
        return make_ready_future<>();
    }
    checksummer csum;
    csum.sum(reinterpret_cast<char*>(iph), sizeof(*iph));
    if (csum.get() != 0) {
        return make_ready_future<>();
    }
    auto h = ntoh(*iph);
    // FIXME: process options
    if (in_my_netmask(h.src_ip) && h.src_ip != _host_address) {
        _arp.learn(from, h.src_ip);
    }
    if (h.frag & 0x3fff) {
        // FIXME: defragment
        return make_ready_future<>();
    }

    if (_packet_filter) {
        bool handled = false;
        auto r = _packet_filter->handle(p, &h, from, handled);
        if (handled) {
            return std::move(r);
        }
    }

    if (h.dst_ip != _host_address) {
        // FIXME: forward
        return make_ready_future<>();
    }
    auto l4 = _l4[h.ip_proto];
    if (l4) {
        unsigned ip_len = h.len;
        unsigned ip_hdr_len = h.ihl * 4;
        unsigned ip_payload_len = ip_len - ip_hdr_len;
        if (p.len() < ip_len) {
            return make_ready_future<>();
        }
        p.trim_front(ip_hdr_len);
        if (p.len() > ip_payload_len) {
            p.trim_back(p.len() - ip_payload_len);
        }
        l4->received(std::move(p), h.src_ip, h.dst_ip);
    }
    return make_ready_future<>();
}

future<> ipv4::send(ipv4_address to, ip_protocol_num proto_num, packet p) {
    uint16_t remaining = p.len();
    uint16_t offset = 0;
    auto needs_frag = this->needs_frag(p, proto_num, hw_features());

    // Figure out where to send the packet to. If it is a directly connected
    // host, send to it directly, otherwise send to the default gateway.
    ipv4_address dst;
    if (in_my_netmask(to)) {
        dst = to;
    } else {
        dst = _gw_address;
    }


    auto send_pkt = [this, to, dst, proto_num, needs_frag] (packet& pkt, uint16_t remaining, uint16_t offset) {
        auto iph = pkt.prepend_header<ip_hdr>();
        iph->ihl = sizeof(*iph) / 4;
        iph->ver = 4;
        iph->dscp = 0;
        iph->ecn = 0;
        iph->len = pkt.len();
        // FIXME: a proper id
        iph->id = 0;
        if (needs_frag) {
            uint16_t mf = remaining > 0;
            // The fragment offset is measured in units of 8 octets (64 bits)
            auto off = offset / 8;
            iph->frag = (mf << uint8_t(ip_hdr::frag_bits::mf)) | off;
        } else {
            iph->frag = 0;
        }
        iph->ttl = 64;
        iph->ip_proto = (uint8_t)proto_num;
        iph->csum = 0;
        iph->src_ip = _host_address;
        iph->dst_ip = to;
        *iph = hton(*iph);

        checksummer csum;
        csum.sum(reinterpret_cast<char*>(iph), sizeof(*iph));
        iph->csum = csum.get();

        return _arp.lookup(dst).then([this, pkt = std::move(pkt)] (ethernet_address e_dst) mutable {
            return send_raw(e_dst, std::move(pkt));
        });
    };

    if (needs_frag) {
        struct send_info {
            packet p;
            uint16_t remaining;
            uint16_t offset;
        };
        auto si = make_shared<send_info>({std::move(p), remaining, offset});
        auto stop = [si] { return si->remaining == 0; };
        auto send_frag = [this, send_pkt, si] () mutable {
            auto& remaining = si->remaining;
            auto& offset = si->offset;
            auto mtu = hw_features().mtu;
            auto can_send = std::min(uint16_t(mtu - net::ipv4_hdr_len_min), remaining);
            remaining -= can_send;
            auto pkt = si->p.share(offset, can_send);
            auto ret = send_pkt(pkt, remaining, offset);
            offset += can_send;
            return ret;
        };
        return do_until(stop, send_frag);
    } else {
        // The whole packet can be send in one shot
        remaining = 0;
        return send_pkt(p, remaining, offset);
    }
}

future<> ipv4::send_raw(ethernet_address dst, packet p) {
    return _l3.send(dst, std::move(p));
}

void ipv4::set_host_address(ipv4_address ip) {
    _host_address = ip;
    _arp.set_self_addr(ip);
}

ipv4_address ipv4::host_address() {
    return _host_address;
}

void ipv4::set_gw_address(ipv4_address ip) {
    _gw_address = ip;
}

ipv4_address ipv4::gw_address() const {
    return _gw_address;
}

void ipv4::set_netmask_address(ipv4_address ip) {
    _netmask = ip;
}

ipv4_address ipv4::netmask_address() const {
    return _netmask;
}

void ipv4::set_packet_filter(ip_packet_filter * f) {
    _packet_filter = f;
}

ip_packet_filter * ipv4::packet_filter() const {
    return _packet_filter;
}

void ipv4::register_l4(ipv4::proto_type id, ip_protocol *protocol) {
    _l4.at(id) = protocol;
}

void icmp::received(packet p, ipaddr from, ipaddr to) {
    auto hdr = p.get_header<icmp_hdr>(0);
    if (!hdr || hdr->type != icmp_hdr::msg_type::echo_request) {
        return;
    }
    hdr->type = icmp_hdr::msg_type::echo_reply;
    hdr->code = 0;
    hdr->csum = 0;
    checksummer csum;
    csum.sum(reinterpret_cast<char*>(hdr), p.len());
    hdr->csum = csum.get();
    _inet.send(to, from, std::move(p));
}

}