bgp_session.cc

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/*
 * Copyright (c) 2013 Juniper Networks, Inc. All rights reserved.
 */

#include "bgp/bgp_session.h"

#include <algorithm>
#include <string>

#include "bgp/bgp_log.h"
#include "bgp/bgp_peer.h"
#include "bgp/bgp_server.h"
#include "bgp/bgp_session_manager.h"
#include "bgp/bgp_update_sender.h"

using std::string;

using boost::asio::mutable_buffer;

// Extract the total BGP message length. This is a 2 byte field after the
// 16 byte marker. If the buffer doesn't have 18 bytes available return -1.
int BgpMessageReader::MsgLength(Buffer buffer, int offset) {
    size_t size = TcpSession::BufferSize(buffer);
    int remain = size - offset;
    if (remain < BgpMessageReader::kHeaderLenSize) {
        return -1;
    }
    const uint8_t *data = TcpSession::BufferData(buffer) + offset;
    data += 16;
    int length = get_value(data, 2);
    if (bgp_log_test::unit_test())
        assert(length <= 4096);
    return length;
}

BgpMessageReader::BgpMessageReader(TcpSession *session,
    ReceiveCallback callback)
    : TcpMessageReader(session, callback) {
}

BgpMessageReader::~BgpMessageReader() {
}

BgpSession::BgpSession(BgpSessionManager *session_mgr, Socket *socket)
    : TcpSession(session_mgr, socket),
      session_mgr_(session_mgr),
      peer_(NULL),
      task_instance_(-1),
      reader_(new BgpMessageReader(this,
              boost::bind(&BgpSession::ReceiveMsg, this, _1, _2))) {
}

BgpSession::~BgpSession() {
}

//
// Concurrency: called in the context of io::Reader task.
//
bool BgpSession::ReceiveMsg(const u_int8_t *msg, size_t size) {
    return (peer_ ? peer_->ReceiveMsg(this, msg, size) : false);
}

//
// Concurrency: called in the context of bgp::Config task.
//
// Process write ready callback.
//
// 1. Tell BgpUpdateSender that the IPeer is send ready.
// 2. Tell BgpPeer that it's send ready so that it can resume Keepalives.
//
void BgpSession::ProcessWriteReady() {
    if (!peer_)
        return;
    BgpServer *server = peer_->server();
    BgpUpdateSender *sender = server->update_sender();
    sender->PeerSendReady(peer_);
    peer_->SetSendReady();
}

//
// Concurrency: called in the context of io thread.
//
// Handle write ready callback.  Enqueue the session to a WorkQueue in the
// BgpSessionManager.  The WorkQueue gets processed in the context of the
// bgp::Config task.  This ensures that we don't access the BgpPeer while
// the BgpPeer is trying to clear our back pointer to it.
//
// We can ignore any errors since the StateMachine will get informed of the
// TcpSession close independently and react to it.
//
void BgpSession::WriteReady(const boost::system::error_code &error) {
    if (error)
        return;
    session_mgr_->EnqueueWriteReady(this);
}

void BgpSession::LogNotification(int code, int subcode, const string &direction,
                                 const string &peer_key,
                                 const BgpProto::Notification &msg) const {
    // Use SYS_DEBUG for connection collision, SYS_NOTICE for the rest.
    if (code == BgpProto::Notification::Cease &&
        subcode == BgpProto::Notification::ConnectionCollision) {
        BGP_LOG(BgpPeerNotification, SandeshLevel::SYS_DEBUG, BGP_LOG_FLAG_ALL,
                peer_key, direction, code, subcode, msg.ToString());
    } else {
        BGP_LOG(BgpPeerNotificationNotice, SandeshLevel::SYS_NOTICE,
                BGP_LOG_FLAG_ALL, peer_key, direction, code, subcode,
                msg.ToString());
    }
}

void BgpSession::SendNotification(int code, int subcode,
                                  const string &data) {
    BgpProto::Notification msg;
    msg.error = code;
    msg.subcode = subcode;
    msg.data = data;
    uint8_t buf[BgpProto::kMaxMessageSize];
    int msglen = BgpProto::Encode(&msg, buf, sizeof(buf));

    LogNotification(code, subcode, BGP_PEER_DIR_OUT,
                    peer_ ? peer_->ToUVEKey() : ToString(), msg);
    if (msglen > BgpProto::kMinMessageSize) {
        Send(buf, msglen, NULL);
    }
}

void BgpSession::set_peer(BgpPeer *peer) {
    peer_ = peer;
    task_instance_ = peer_->GetTaskInstance();
}

//
// Dissociate the peer from the this BgpSession.
// Do not invalidate the task_instance since it can be used to spawn an
// io::ReaderTask while this method is being executed.
//
void BgpSession::clear_peer() {
    peer_ = NULL;
}