1 files changed, 49 insertions, 0 deletions
diff --git a/handshake.go b/handshake.go
new file mode 100644
index 0000000..bbd100c
--- /dev/null
+++ b/handshake.go
@@ -0,0 +1,49 @@
+package main
+
+import (
+	"golang/org/x/sync/errgroup"
+
+	"key"
+)
+
+// handshake exchanges public keys with a remote host.
+// The user is asked to verify the fingerprint of the received key
+// before it is saved in the known hosts file.
+func handshake(rhost string) error {
+	logf("initiating handshake with %s...", rhost)
+	var group errgroup.Group
+	group.Go(handshakeSend(rhost))
+	group.Go(handshakeRecv(rhost))
+	return group.Wait()
+}
+
+// handshakeSend sends the local public key to a remote host.
+func handshakeSend(rhost string) error {
+	pubkey, err := key.LoadPublicKey()
+	if err != nil {
+		return err
+	}
+
+	raddr := net.JoinHostPort(rhost, port)
+	logf("connecting to %s...", raddr)
+	conn, err := net.Dial(network, raddr)
+	if err != nil {
+		return err
+	}
+	defer conn.Close()
+	logf("connected to %s", raddr)
+
+	if _, err := conn.Write(pubkey[:]); err != nil {
+		return err
+	}
+
+	logf("sent public key to %s", rhost)
+	return nil
+}
+
+// handshakeRecv receives the public key of a remote host.
+// The user is asked to verify the fingerprint of the key before
+// it is saved to the known hosts file.
+func handshakeRecv(rhost string) error {
+	// TODO
+}