ssh/knownhosts: knownhost to support io.reader

ssh/knownhosts/reader.go

@@ -0,0 +1,27 @@
+package knownhosts
+
+import (
+	"io"
+
+	"golang.org/x/crypto/ssh"
+)
+
+// NewFromReader creates a host key callback from the given OpenSSH host io.Reader
+// which is in SSH_KNOWN_HOSTS_FILE_FORMAT. The returned callback is for use in
+// ssh.ClientConfig.HostKeyCallback. By preference, the key check
+// operates on the hostname if available, i.e. if a server changes its
+// IP address, the host key check will still succeed, even though a
+// record of the new IP address is not available.
+func NewFromReader(r io.Reader) (ssh.HostKeyCallback, error) {
+	db := newHostKeyDB()
+	if err := db.Read(r, ""); err != nil {
+		return nil, err
+	}
+
+	var certChecker ssh.CertChecker
+	certChecker.IsHostAuthority = db.IsHostAuthority
+	certChecker.IsRevoked = db.IsRevoked
+	certChecker.HostKeyFallback = db.check
+
+	return certChecker.CheckHostKey, nil
+}

ssh/knownhosts/reader_test.go

@@ -0,0 +1,17 @@
+package knownhosts
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+)
+
+func TestNewFromReader(t *testing.T) {
+	str := fmt.Sprintf("server*.domain %s", edKeyStr)
+
+	_, err := NewFromReader(strings.NewReader(str))
+	if err != nil {
+		t.Fatalf("cannot read from string: %v", err)
+	}
+
+}