Initial working version

vendor/github.com/xor-gate/sshfp/entry.go

@@ -0,0 +1,64 @@
+package sshfp
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"fmt"
+	"math"
+	"time"
+
+	"github.com/miekg/dns"
+	"golang.org/x/crypto/ssh"
+)
+
+// Entry wraps a DNS SSHFP entry used for caching
+type Entry struct {
+	*dns.SSHFP
+	ExpiresAt   time.Time
+	Hostname    string
+	Fingerprint []byte
+}
+
+// Entries for a single Hostname
+type Entries []*Entry
+
+// Validate checks if the SSH public key is valid
+func (e *Entry) Validate(pubKey ssh.PublicKey) bool {
+	if e.Fingerprint == nil {
+		return false
+	}
+	fp := sha256.Sum256(pubKey.Marshal())
+	return bytes.Equal(e.Fingerprint, fp[:])
+}
+
+// TTL calculates the remaining seconds the entry is valid. When ExpiresAt field is zero then it
+//  never expires and returns math.MaxUint32.
+func (e *Entry) TTL() uint32 {
+	if e.ExpiresAt.IsZero() {
+		return math.MaxUint32
+	}
+	ttl := time.Until(e.ExpiresAt)
+	if ttl < 1 {
+		return 0
+	}
+	return uint32(ttl / time.Second)
+}
+
+// IsExpired checks if the entry is expired
+func (e *Entry) IsExpired() bool {
+	if e.ExpiresAt.IsZero() {
+		return false
+	}
+	return time.Now().After(e.ExpiresAt)
+}
+
+// IsValid checks if the entry is valid
+func (e *Entry) IsValid() bool {
+	return true
+}
+
+// String creates a human readable presentation of the SSHFP entry
+// <hostname> <algorithm string> <fingerprint type string>
+func (e *Entry) String() string {
+	return fmt.Sprintf("%s %s %s", e.Hostname, Algorithm(e.SSHFP.Algorithm), Type(e.SSHFP.Type))
+}