From e18d36ebae30536c77c61cd5da123991e0ca1629 Mon Sep 17 00:00:00 2001
From: Rasmus Dahlberg <rasmus@rgdd.se>
Date: Sun, 31 Dec 2023 09:39:25 +0100
Subject: Add drafty prototype

---
 pkg/storage/index/inmem.go | 113 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 pkg/storage/index/inmem.go

(limited to 'pkg/storage/index/inmem.go')

diff --git a/pkg/storage/index/inmem.go b/pkg/storage/index/inmem.go
new file mode 100644
index 0000000..0a084bf
--- /dev/null
+++ b/pkg/storage/index/inmem.go
@@ -0,0 +1,113 @@
+package index
+
+import (
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/google/certificate-transparency-go/x509"
+	"rgdd.se/silent-ct/pkg/crtutil"
+)
+
+type CertificateID string
+
+func (crtID *CertificateID) Set(crt x509.Certificate) {
+	*crtID = CertificateID(crtutil.UniqueID(crt))
+}
+
+type CertificateInfo struct {
+	ObservedAt time.Time `json:"observed_at"`
+	StoredAt   string    `json:"stored_at"`
+}
+
+// index is an in-memory index of certificates
+type index struct {
+	Alerting   map[CertificateID][]CertificateInfo `json:"alerting"`   // Certificates that were not marked as "good" on time
+	Legitimate map[CertificateID][]CertificateInfo `json:"legitimate"` // Certificates that are considered "good"
+	Pending    map[CertificateID][]CertificateInfo `json:"pending"`    // Certificates that have yet to be marked as "good"
+}
+
+func newIndex() index {
+	return index{
+		Alerting:   make(map[CertificateID][]CertificateInfo),
+		Legitimate: make(map[CertificateID][]CertificateInfo),
+		Pending:    make(map[CertificateID][]CertificateInfo),
+	}
+}
+
+func (ix *index) JSONUnmarshal(b []byte) error {
+	type internal index
+	if err := json.Unmarshal(b, (*internal)(ix)); err != nil {
+		return err
+	}
+	for i, m := range []map[CertificateID][]CertificateInfo{ix.Alerting, ix.Legitimate, ix.Pending} {
+		if m == nil {
+			return fmt.Errorf("dictionary named %q is not in the index", []string{"alerting", "legitimate", "pending"}[i])
+		}
+	}
+	return nil
+}
+
+func (ix *index) triggerAlerts(delay time.Duration) []CertificateInfo {
+	var alerts []CertificateInfo
+
+	for key, certInfos := range ix.Pending {
+		certInfo := certInfos[0]
+		if time.Since(certInfo.ObservedAt) < delay {
+			continue
+		}
+
+		alerts = append(alerts, certInfo)
+		ix.Alerting[key] = certInfos
+		delete(ix.Pending, key)
+	}
+
+	return alerts
+}
+
+func (ix *index) addChain(crtID CertificateID, path string) bool {
+	if _, ok := ix.Legitimate[crtID]; ok {
+		return false // we already marked this certificate as "good"
+	}
+
+	entry := CertificateInfo{ObservedAt: time.Now(), StoredAt: path}
+	crtInfos := []CertificateInfo{entry}
+	if v, ok := ix.Alerting[crtID]; ok {
+		crtInfos = append(crtInfos, v...)
+		delete(ix.Alerting, crtID) // no longer alerting
+	} else if v, ok := ix.Pending[crtID]; ok {
+		crtInfos = append(crtInfos, v...)
+		delete(ix.Pending, crtID) // no longer pending
+	}
+
+	ix.Legitimate[crtID] = crtInfos
+	return true // index updated such that this certificate is marked as "good"
+}
+
+func (ix *index) addEntry(crtID CertificateID, path string) bool {
+	crtInfo := CertificateInfo{ObservedAt: time.Now(), StoredAt: path}
+	if _, ok := ix.Legitimate[crtID]; ok {
+		return add(ix.Legitimate, crtID, crtInfo)
+	} else if _, ok := ix.Alerting[crtID]; ok {
+		return add(ix.Alerting, crtID, crtInfo)
+	}
+	return add(ix.Pending, crtID, crtInfo)
+}
+
+func add(m map[CertificateID][]CertificateInfo, key CertificateID, value CertificateInfo) bool {
+	crtInfos, ok := m[key]
+	if !ok {
+		m[key] = []CertificateInfo{value}
+		return true
+	}
+
+	for _, crtInfo := range crtInfos {
+		if value.StoredAt == crtInfo.StoredAt {
+			return false // duplicate
+		}
+	}
+
+	crtInfos = append(crtInfos, value)
+	m[key] = crtInfos
+	return true
+}
-- 
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