refactor handshake

3 files changed, 208 insertions, 174 deletions

diff --git a/handshake/handshake.go b/handshake/handshake.go
index 880e907..e5e3c37 100644
--- a/handshake/handshake.go
+++ b/handshake/handshake.go
@@ -1,21 +1,10 @@
 package handshake
 
 import (
-	"bufio"
 	"context"
-	"errors"
-	"fmt"
 	"golang.org/x/sync/errgroup"
-	"io"
-	"net"
-	"net/netip"
-	"os"
-	"slices"
-	"strings"
 	"time"
 
-	"git.samanthony.xyz/hose/hosts"
-	"git.samanthony.xyz/hose/key"
 	"git.samanthony.xyz/hose/util"
 )
 
@@ -27,15 +16,6 @@ const (
 	retryInterval = 500 * time.Millisecond
 )
 
-var errHostKey = errors.New("host key verification failed")
-
-type keyType string
-
-const (
-	boxPublicKey keyType = "Public encryption key"
-	sigPublicKey         = "Public signature verification key"
-)
-
 // Handshake exchanges public keys with a remote host.
 // The user is asked to verify the received keys before they are saved in the known hosts file.
 func Handshake(rhost string) error {
@@ -66,157 +46,3 @@ func Handshake(rhost string) error {
 		return nil
 	}
 }
-
-// send sends the local public box (encryption) key to a remote host.
-func send(rhost string) error {
-	pubBoxkey, err := key.LoadBoxPublicKey()
-	if err != nil {
-		return err
-	}
-
-	pubSigKey, err := key.LoadSigPublicKey()
-	if err != nil {
-		return err
-	}
-
-	raddr := net.JoinHostPort(rhost, port)
-	util.Logf("connecting to %s...", raddr)
-	conn, err := dialWithTimeout(network, raddr, timeout)
-	if err != nil {
-		return err
-	}
-	defer conn.Close()
-	util.Logf("connected to %s", raddr)
-
-	if _, err := conn.Write(pubBoxkey[:]); err != nil {
-		return err
-	}
-	if _, err := conn.Write(pubSigKey[:]); err != nil {
-		return err
-	}
-
-	util.Logf("sent public keys to %s", rhost)
-	return nil
-}
-
-func dialWithTimeout(network, address string, timeout time.Duration) (net.Conn, error) {
-	ctx, cancel := context.WithTimeout(context.Background(), timeout)
-	defer cancel()
-	for {
-		select {
-		case <-ctx.Done(): // timeout.
-			return nil, fmt.Errorf("dial %s %s: connection refused", network, address)
-		default:
-		}
-		conn, err := net.Dial(network, address)
-		if err == nil {
-			return conn, nil
-		}
-		time.Sleep(retryInterval)
-	}
-}
-
-// receive receives the public keys of a remote host.
-// The user is asked to verify the keys before they are saved to the known hosts file.
-func receive(rhost string) error {
-	// Listen for connection.
-	laddr := net.JoinHostPort("", port)
-	ln, err := net.Listen(network, laddr)
-	if err != nil {
-		return err
-	}
-	defer ln.Close()
-	util.Logf("listening on %s", laddr)
-
-	conn, err := ln.Accept()
-	if err != nil {
-		return err
-	}
-	defer conn.Close()
-	util.Logf("accepted connection from %s", conn.RemoteAddr())
-
-	// Receive public box (encryption) key from remote host.
-	var rBoxPubKey key.BoxPublicKey
-	_, err = io.ReadFull(conn, rBoxPubKey[:])
-	if err != nil {
-		return err
-	}
-	util.Logf("received public encryption key from %s", conn.RemoteAddr())
-
-	// Receive public signature verification key from remote host.
-	var rSigPubKey key.SigPublicKey
-	_, err = io.ReadFull(conn, rSigPubKey[:])
-	if err != nil {
-		return err
-	}
-	util.Logf("receive public signature verification key from %s", conn.RemoteAddr())
-
-	// Ask user to verify the keys.
-	host, _, err := net.SplitHostPort(conn.RemoteAddr().String())
-	if err != nil {
-		return err
-	}
-	raddr, err := netip.ParseAddr(host)
-	if err != nil {
-		return err
-	}
-	// Verify box key.
-	ok, err := verifyKey(raddr, rBoxPubKey[:], boxPublicKey)
-	if err != nil {
-		return err
-	}
-	if !ok { // user rejected the key.
-		return errHostKey
-	}
-	// Verify signature verification key.
-	ok, err = verifyKey(raddr, rSigPubKey[:], sigPublicKey)
-	if err != nil {
-		return err
-	}
-	if !ok { // user rejected the key.
-		return errHostKey
-	}
-
-	// Save in known hosts file.
-	return hosts.Add(hosts.Host{raddr, rBoxPubKey, rSigPubKey})
-}
-
-// verifyKey asks the user to verify a key received from a remote host.
-// It returns true if the user accepts the key, or false if they don't, or a non-nil error.
-func verifyKey(host netip.Addr, key []byte, kt keyType) (bool, error) {
-	// Ask host to verify the key.
-	util.Logf("%s key of host %q: %x\nIs this the correct key (yes/[no])?",
-		kt, host, key[:])
-	response, err := scan([]string{"yes", "no", ""})
-	if err != nil {
-		return false, err
-	}
-	switch response {
-	case "yes":
-		return true, nil
-	case "no":
-		return false, nil
-	case "":
-		return false, nil // default option
-	}
-	panic("unreachable")
-}
-
-// scan reads from stdin until the user enters one of the valid responses.
-func scan(responses []string) (string, error) {
-	scanner := bufio.NewScanner(os.Stdin)
-	scanner.Scan()
-	if err := scanner.Err(); err != nil {
-		return "", err
-	}
-	response := strings.TrimSpace(scanner.Text())
-	for !slices.Contains(responses, response) {
-		util.Logf("Please enter one of %q", responses)
-		scanner.Scan()
-		if err := scanner.Err(); err != nil {
-			return "", err
-		}
-		response = strings.TrimSpace(scanner.Text())
-	}
-	return response, nil
-}
diff --git a/handshake/receive.go b/handshake/receive.go
new file mode 100644
index 0000000..986b967
--- /dev/null
+++ b/handshake/receive.go
@@ -0,0 +1,139 @@
+package handshake
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"net"
+	"net/netip"
+	"os"
+	"slices"
+	"strings"
+
+	"git.samanthony.xyz/hose/hosts"
+	"git.samanthony.xyz/hose/key"
+	"git.samanthony.xyz/hose/util"
+)
+
+type keyType string
+
+const (
+	boxPublicKey keyType = "Public encryption key"
+	sigPublicKey         = "Public signature verification key"
+)
+
+var errVerifyKey = errors.New("host key verification failed")
+
+// receive receives the public keys of a remote host.
+// The user is asked to verify the keys before they are saved to the known hosts file.
+func receive(rhost string) error {
+	conn, err := acceptConnection()
+	if err != nil {
+		return err
+	}
+	defer conn.Close()
+	util.Logf("accepted connection from %s", conn.RemoteAddr())
+
+	rBoxPubKey, rSigPubKey, err := receiveKeys(conn)
+	if err != nil {
+		return err
+	}
+
+	// Ask user to verify the keys.
+	host, _, err := net.SplitHostPort(conn.RemoteAddr().String())
+	if err != nil {
+		return err
+	}
+	raddr, err := netip.ParseAddr(host)
+	if err != nil {
+		return err
+	}
+	if err := verifyKeys(raddr, rBoxPubKey, rSigPubKey); err != nil {
+		return err
+	}
+
+	// Save in known hosts file.
+	return hosts.Add(hosts.Host{raddr, rBoxPubKey, rSigPubKey})
+}
+
+func acceptConnection() (net.Conn, error) {
+	laddr := net.JoinHostPort("", port)
+	ln, err := net.Listen(network, laddr)
+	if err != nil {
+		return nil, err
+	}
+	defer ln.Close()
+	util.Logf("listening on %s", laddr)
+	return ln.Accept()
+}
+
+func receiveKeys(conn net.Conn) (key.BoxPublicKey, key.SigPublicKey, error) {
+	// Receive public box (encryption) key from remote host.
+	var rBoxPubKey key.BoxPublicKey
+	_, err := io.ReadFull(conn, rBoxPubKey[:])
+	if err != nil {
+		return key.BoxPublicKey{}, key.SigPublicKey{}, err
+	}
+	util.Logf("received public encryption key from %s", conn.RemoteAddr())
+
+	// Receive public signature verification key from remote host.
+	var rSigPubKey key.SigPublicKey
+	_, err = io.ReadFull(conn, rSigPubKey[:])
+	if err != nil {
+		return key.BoxPublicKey{}, key.SigPublicKey{}, err
+	}
+	util.Logf("receive public signature verification key from %s", conn.RemoteAddr())
+
+	return rBoxPubKey, rSigPubKey, nil
+}
+
+// verifyKeys asks the user to verify keys received from a remote host.
+// It returns a non-nil error if the user rejects the keys.
+func verifyKeys(host netip.Addr, rBoxPubKey key.BoxPublicKey, rSigPubKey key.SigPublicKey) error {
+	// Verify box key.
+	if err := verifyKey(host, rBoxPubKey[:], boxPublicKey); err != nil {
+		return err
+	}
+	// Verify signature verification key.
+	return verifyKey(host, rSigPubKey[:], sigPublicKey)
+}
+
+// verifyKey asks the user to verify a key received from a remote host.
+// It returns a non-nil error if the user rejects the key.
+func verifyKey(host netip.Addr, key []byte, kt keyType) error {
+	// Ask host to verify the key.
+	util.Logf("%s key of host %q: %x\nIs this the correct key (yes/[no])?",
+		kt, host, key[:])
+	response, err := scan([]string{"yes", "no", ""})
+	if err != nil {
+		return err
+	}
+	switch response {
+	case "yes":
+		return nil
+	case "no":
+		return errVerifyKey
+	case "":
+		return errVerifyKey // default option
+	}
+	panic("unreachable")
+}
+
+// scan reads from stdin until the user enters one of the valid responses.
+func scan(responses []string) (string, error) {
+	scanner := bufio.NewScanner(os.Stdin)
+	scanner.Scan()
+	if err := scanner.Err(); err != nil {
+		return "", err
+	}
+	response := strings.TrimSpace(scanner.Text())
+	for !slices.Contains(responses, response) {
+		util.Logf("Please enter one of %q", responses)
+		scanner.Scan()
+		if err := scanner.Err(); err != nil {
+			return "", err
+		}
+		response = strings.TrimSpace(scanner.Text())
+	}
+	return response, nil
+}
diff --git a/handshake/send.go b/handshake/send.go
new file mode 100644
index 0000000..444db70
--- /dev/null
+++ b/handshake/send.go
@@ -0,0 +1,69 @@
+package handshake
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"time"
+
+	"git.samanthony.xyz/hose/key"
+	"git.samanthony.xyz/hose/util"
+)
+
+// send sends the local public box (encryption) key to a remote host.
+func send(rhost string) error {
+	// Load keys from disc.
+	boxPubKey, sigPubKey, err := loadKeys()
+	if err != nil {
+		return err
+	}
+	// Send them to the remote host.
+	return sendKeys(rhost, boxPubKey, sigPubKey)
+}
+
+func loadKeys() (key.BoxPublicKey, key.SigPublicKey, error) {
+	boxPubKey, err := key.LoadBoxPublicKey()
+	if err != nil {
+		return key.BoxPublicKey{}, key.SigPublicKey{}, err
+	}
+	sigPubKey, err := key.LoadSigPublicKey()
+	return boxPubKey, sigPubKey, err
+}
+
+func sendKeys(rhost string, boxPubKey key.BoxPublicKey, sigPubKey key.SigPublicKey) error {
+	raddr := net.JoinHostPort(rhost, port)
+	util.Logf("connecting to %s...", raddr)
+	conn, err := dialWithTimeout(network, raddr, timeout)
+	if err != nil {
+		return err
+	}
+	defer conn.Close()
+	util.Logf("connected to %s", raddr)
+
+	if _, err := conn.Write(boxPubKey[:]); err != nil {
+		return err
+	}
+	if _, err := conn.Write(sigPubKey[:]); err != nil {
+		return err
+	}
+	util.Logf("sent public keys to %s", rhost)
+
+	return nil
+}
+
+func dialWithTimeout(network, address string, timeout time.Duration) (net.Conn, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+	for {
+		select {
+		case <-ctx.Done(): // timeout.
+			return nil, fmt.Errorf("dial %s %s: connection refused", network, address)
+		default:
+		}
+		conn, err := net.Dial(network, address)
+		if err == nil {
+			return conn, nil
+		}
+		time.Sleep(retryInterval)
+	}
+}