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package monitor
import (
"context"
"crypto/sha256"
"fmt"
"sync"
"time"
ct "github.com/google/certificate-transparency-go"
"github.com/google/certificate-transparency-go/client"
"github.com/google/certificate-transparency-go/scanner"
"gitlab.torproject.org/rgdd/ct/pkg/merkle"
)
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()
for {
select {
case <-ctx.Done():
return // FIXME: check if we can pop something before return
case c := <-chunkCh:
heap.push(c)
if heap.gap(state.NextIndex) {
continue
}
c = heap.pop()
if len(c.matches) == 0 && len(c.leafHashes) < int(t.cfg.ChunkSize) {
heap.push(c)
continue // FIXME: don't trigger if we havn't run nextState for too long
}
nextState, err := t.nextState(ctx, state, c)
if err != nil {
errorCh <- err
heap.push(c)
continue
}
state = nextState
eventCh <- Event{State: state, Matches: c.matches, Errors: c.errors}
}
}
}
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 := getSignedTreeHead(ctx, t.checker)
if err != nil {
return State{}, fmt.Errorf("%s: get-sth: %v", t.checker.BaseURI(), err)
}
sth.LogID = state.SignedTreeHead.LogID
oldSize := state.TreeSize
oldRoot := state.SHA256RootHash
newSize := sth.TreeSize
newRoot := sth.SHA256RootHash
proof, err := 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, unslice(proof)); err != nil {
return State{}, fmt.Errorf("%s: verify consistency: %v", t.checker.BaseURI(), err)
}
return State{SignedTreeHead: *sth, NextIndex: state.NextIndex}, nil
}
func (t *tail) nextIncludedState(ctx context.Context, state State, c *chunk) (State, error) {
leafHash := c.leafHashes[0]
oldSize := state.NextIndex + uint64(len(c.leafHashes))
iproof, err := getInclusionProof(ctx, t.checker, leafHash, oldSize) // FIXME: set leaf index in ctx to hack into tile API
if err != nil {
return State{}, fmt.Errorf("%s: get-inclusion: %v", t.checker.BaseURI(), err)
}
if got, want := uint64(iproof.LeafIndex), state.NextIndex; got != want {
return State{}, fmt.Errorf("%s: wrong index for get-inclusion proof query %x:%d", t.checker.BaseURI(), leafHash[:], oldSize)
}
oldRoot, err := merkle.TreeHeadFromRangeProof(c.leafHashes, state.NextIndex, unslice(iproof.AuditPath))
if err != nil {
return State{}, fmt.Errorf("%s: range proof: %v", t.checker.BaseURI(), err)
}
newSize := state.TreeSize
newRoot := state.SHA256RootHash
cproof, err := 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, unslice(cproof)); err != nil {
return State{}, fmt.Errorf("%s: verify consistency: %v", t.checker.BaseURI(), err)
}
state.NextIndex += uint64(len(c.leafHashes))
return state, nil
}
func getInclusionProof(ctx context.Context, cli client.CheckLogClient, leafHash [sha256.Size]byte, size uint64) (*ct.GetProofByHashResponse, error) {
rctx, cancel := context.WithTimeout(ctx, 10*time.Second)
defer cancel()
return cli.GetProofByHash(rctx, leafHash[:], size)
}
func getConsistencyProof(ctx context.Context, cli client.CheckLogClient, oldSize, newSize uint64) ([][]byte, error) {
if oldSize == 0 || oldSize >= newSize {
return [][]byte{}, nil
}
rctx, cancel := context.WithTimeout(ctx, 10*time.Second)
defer cancel()
return cli.GetSTHConsistency(rctx, oldSize, newSize)
}
func getSignedTreeHead(ctx context.Context, cli client.CheckLogClient) (*ct.SignedTreeHead, error) {
rctx, cancel := context.WithTimeout(ctx, 10*time.Second)
defer cancel()
return cli.GetSTH(rctx)
}
func unslice(hashes [][]byte) [][sha256.Size]byte {
var ret [][sha256.Size]byte
for _, hash := range hashes {
var h [sha256.Size]byte
copy(h[:], hash)
ret = append(ret, h)
}
return ret
}
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