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|
// Package monitor provides monitoring of Certificate Transparency logs. If
// running in continuous mode, the list of logs can be updated dynamically.
//
// Implement the Matcher interface to customize which certificates should be
// included in the monitor's emitted events. See MatchAll for an example.
//
// Note that this package verifies that the monitored logs are locally
// consistent with regard to the initial start-up state. It is up to the user
// to process the monitor's emitted events and errors, and to persist state.
package monitor
import (
"context"
"crypto/x509"
"encoding/base64"
"fmt"
"net/http"
"os"
"sync"
ct "github.com/google/certificate-transparency-go"
"github.com/google/certificate-transparency-go/client"
"github.com/google/certificate-transparency-go/jsonclient"
"gitlab.torproject.org/rgdd/ct/pkg/metadata"
"rgdd.se/silent-ct/internal/logger"
)
// MonitoredLog provides information about a log the monitor is following
type MonitoredLog struct {
Config metadata.Log
State State
}
// State is the latest append-only state the monitor observed from its local
// vantage point. The next entry to download is specified by NextIndex.
type State struct {
ct.SignedTreeHead `json:"latest_sth"`
NextIndex uint64 `json:"next_index"`
}
// Event carries the latest consistent monitor state, found matches, as well as
// errors that occurred while trying to match on the downloaded log entries.
type Event struct {
State State
Matches []LogEntry
Errors []error
}
func (ev *Event) Summary() string {
return fmt.Sprintf("log %s: tree size %d at next index %d (%d matches, %d errors)",
base64.StdEncoding.EncodeToString(ev.State.LogID[:]),
ev.State.TreeSize, ev.State.NextIndex, len(ev.Matches), len(ev.Errors))
}
// LogEntry is a Merkle tree leaf in a log
type LogEntry struct {
LeafIndex uint64 `json:"leaf_index"`
LeafData []byte `json:"leaf_data"`
ExtraData []byte `json:"extra_data"`
}
type Config struct {
// Optional
Matcher Matcher // Which log entries to match (default is to match all)
Logger *logger.Logger // Debug prints only (no output by default)
Contact string // Something that help log operators get in touch
ChunkSize uint // Min number of leaves to propagate a chunk without matches
BatchSize uint // Max number of certificates to accept per worker
NumWorkers uint // Number of parallel workers to use for each log
}
type Monitor struct {
cfg Config
matcher Matcher
eventCh chan Event
configCh chan MonitoredLog
errorCh chan error
}
func New(cfg Config, evCh chan Event, cfgCh chan MonitoredLog, errCh chan error) (Monitor, error) {
if cfg.Matcher == nil {
cfg.Matcher = &MatchAll{}
}
if !cfg.Logger.IsConfigured() {
cfg.Logger = logger.New(logger.Config{Level: logger.LevelNotice, File: os.Stderr})
}
if cfg.Contact == "" {
cfg.Contact = "unknown-user"
}
if cfg.ChunkSize == 0 {
cfg.ChunkSize = 16364
}
if cfg.BatchSize == 0 {
cfg.BatchSize = 1024
}
if cfg.NumWorkers == 0 {
cfg.NumWorkers = 2
}
return Monitor{cfg: cfg, matcher: cfg.Matcher, eventCh: evCh, configCh: cfgCh, errorCh: errCh}, nil
}
func (mon *Monitor) RunOnce(ctx context.Context, cfg []MonitoredLog, evCh chan Event, errCh chan error) error {
return fmt.Errorf("TODO")
}
func (mon *Monitor) RunForever(ctx context.Context) error {
var wg sync.WaitGroup
defer wg.Wait()
mctx, cancel := context.WithCancel(ctx)
defer cancel()
monitoring := make(map[metadata.LogURL]context.CancelFunc)
for {
select {
case <-ctx.Done():
return nil
case log := <-mon.configCh:
if tcancel, ok := monitoring[log.Config.URL]; ok {
delete(monitoring, log.Config.URL)
tcancel()
continue
}
newTail := mon.newTailRFC6962
if log.Config.DNS != nil { // FIXME: get a real nob for tile-based logs
newTail = mon.newTailTile
}
t, err := newTail(log)
if err != nil {
return err
}
tctx, tcancel := context.WithCancel(mctx)
monitoring[log.Config.URL] = tcancel
wg.Add(1)
go func(log MonitoredLog, t tail) {
defer wg.Done()
defer tcancel()
t.run(tctx, log, mon.eventCh, mon.errorCh)
}(log, t)
}
}
}
const userAgentPrefix = "rgdd.se/silent-ct"
func (mon *Monitor) newTailRFC6962(log MonitoredLog) (tail, error) {
key, err := x509.MarshalPKIXPublicKey(log.Config.Key.Public)
if err != nil {
return tail{}, err
}
cli, err := client.New(string(log.Config.URL), &http.Client{}, jsonclient.Options{
Logger: &discard{},
UserAgent: userAgentPrefix + "/" + mon.cfg.Contact,
PublicKeyDER: key,
})
if err != nil {
return tail{}, err
}
return tail{cfg: mon.cfg, scanner: cli, checker: cli, matcher: mon.matcher}, nil
}
func (mon *Monitor) newTailTile(cfg MonitoredLog) (tail, error) {
return tail{}, fmt.Errorf("TODO")
}
type discard struct{}
func (n *discard) Printf(string, ...interface{}) {}
|
