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package monitor
import (
"context"
"fmt"
"sync"
"time"
"github.com/google/certificate-transparency-go/client"
"github.com/google/certificate-transparency-go/scanner"
"gitlab.torproject.org/rgdd/ct/pkg/merkle"
"rgdd.se/silentct/internal/ioutil"
"rgdd.se/silentct/internal/logutil"
)
type tail struct {
cfg Config
matcher Matcher
scanner scanner.LogClient
checker client.CheckLogClient
}
func (t *tail) run(ctx context.Context, mon MonitoredLog, eventCh chan Event, errorCh chan error) {
chunkCh := make(chan *chunk)
defer close(chunkCh)
mctx, cancel := context.WithCancel(ctx)
defer cancel()
var wg sync.WaitGroup
defer wg.Wait()
callback := func(eb scanner.EntryBatch) {
c := chunk{startIndex: uint64(eb.Start)}
for i := 0; i < len(eb.Entries); i++ {
c.leafHashes = append(c.leafHashes, merkle.HashLeafNode(eb.Entries[i].LeafInput))
match, err := t.matcher.Match(eb.Entries[i].LeafInput, eb.Entries[i].ExtraData)
if err != nil {
c.errors = append(c.errors, fmt.Errorf("while processing index %d for %s: %v", i, mon.Config.URL, err))
continue
}
if !match {
continue
}
c.matches = append(c.matches, LogEntry{
LeafIndex: c.startIndex + uint64(i),
LeafData: eb.Entries[i].LeafInput,
ExtraData: eb.Entries[i].ExtraData,
})
}
chunkCh <- &c
}
fetcher := scanner.NewFetcher(t.scanner, &scanner.FetcherOptions{
BatchSize: int(t.cfg.BatchSize),
StartIndex: int64(mon.State.NextIndex),
ParallelFetch: int(t.cfg.NumWorkers),
Continuous: true, // FIXME: don't set this for read-only log
})
wg.Add(1)
go func() {
defer wg.Done()
defer cancel()
fetcher.Run(mctx, callback)
}()
wg.Add(1)
go func() {
defer wg.Done()
defer cancel()
t.sequence(mctx, mon, eventCh, errorCh, chunkCh)
}()
}
func (t *tail) sequence(ctx context.Context, mon MonitoredLog, eventCh chan Event, errorCh chan error, chunkCh chan *chunk) {
state := mon.State
heap := newChunks()
sendChunk := func(ctx context.Context, force bool) {
if heap.gap(state.NextIndex) {
return // nothing to send yet
}
c := heap.pop()
if !force && len(c.matches) == 0 && len(c.leafHashes) < int(t.cfg.ChunkSize) {
heap.push(c)
return // wait for a larger chunk before batch verification
}
nextState, err := t.nextState(ctx, state, c)
if err != nil {
errorCh <- err
heap.push(c)
return
}
state = nextState
eventCh <- Event{State: state, Matches: c.matches, Errors: c.errors}
}
refreshSTH := func(ctx context.Context) {
timestamp := time.UnixMilli(int64(state.Timestamp))
timestamp = timestamp.Add(t.cfg.ChunkTime)
timestamp = timestamp.Add(-1 * time.Second)
if timestamp.After(time.Now()) {
return
}
// Looks like we haven't send any chunks the past ChunkTime time units.
// Get a newer tree head so the timestamp can be used for freshness.
nextState, err := t.nextConsistentState(ctx, state)
if err != nil {
errorCh <- err
return
}
state = nextState
eventCh <- Event{State: state}
}
sendTicker := time.NewTicker(t.cfg.ChunkTime)
defer sendTicker.Stop()
for {
select {
case <-ctx.Done():
dctx, cancel := context.WithTimeout(context.Background(), t.cfg.ExitTime)
defer cancel()
sendChunk(dctx, true)
refreshSTH(dctx)
return
case <-sendTicker.C:
sendChunk(ctx, true)
refreshSTH(ctx)
case c := <-chunkCh:
heap.push(c)
sendChunk(ctx, false)
}
}
}
func (t *tail) nextState(ctx context.Context, state State, c *chunk) (State, error) {
newState, err := t.nextConsistentState(ctx, state)
if err != nil {
return State{}, err
}
newState, err = t.nextIncludedState(ctx, newState, c)
if err != nil {
return State{}, err
}
return newState, nil
}
func (t *tail) nextConsistentState(ctx context.Context, state State) (State, error) {
sth, err := logutil.GetSignedTreeHead(ctx, t.checker)
if err != nil {
return State{}, fmt.Errorf("%s: get-sth: %v", t.checker.BaseURI(), err)
}
if sth.Timestamp < state.Timestamp {
return State{}, fmt.Errorf("%s: get-sth: timestamp is shrinking", t.checker.BaseURI())
}
sth.LogID = state.SignedTreeHead.LogID
oldSize := state.TreeSize
oldRoot := state.SHA256RootHash
newSize := sth.TreeSize
newRoot := sth.SHA256RootHash
proof, err := logutil.GetConsistencyProof(ctx, t.checker, oldSize, newSize)
if err != nil {
return State{}, fmt.Errorf("%s: get-consistency: %v", t.checker.BaseURI(), err)
}
if err := merkle.VerifyConsistency(oldSize, newSize, oldRoot, newRoot, proof); err != nil {
return State{}, fmt.Errorf("%s: verify consistency: %v", t.checker.BaseURI(), err)
}
return State{SignedTreeHead: *sth, CompactRange: ioutil.CopyHashes(state.CompactRange), NextIndex: state.NextIndex}, nil
}
func (t *tail) nextIncludedState(ctx context.Context, state State, c *chunk) (State, error) {
cr, err := logutil.AppendCompactRange(state.CompactRange, state.NextIndex, c.leafHashes)
if err != nil {
panic(fmt.Sprintf("bug: %v", err))
}
oldRoot := logutil.RootHash(cr)
oldSize := state.NextIndex + uint64(len(c.leafHashes))
newRoot := state.SHA256RootHash
newSize := state.TreeSize
proof, err := logutil.GetConsistencyProof(ctx, t.checker, oldSize, newSize)
if err != nil {
return State{}, fmt.Errorf("%s: tree: get-consistency: %v", t.checker.BaseURI(), err)
}
if err := merkle.VerifyConsistency(oldSize, newSize, oldRoot, newRoot, proof); err != nil {
return State{}, fmt.Errorf("%s: tree: verify consistency: %v", t.checker.BaseURI(), err)
}
state.NextIndex += uint64(len(c.leafHashes))
state.CompactRange = ioutil.UnsliceHashes(cr.Hashes())
return state, nil
}
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