Knownhosts tilde aware path expansion - fixes #1107

libvirt/uri/ssh.go

@@ -5,13 +5,14 @@ import (
 	"log"
 	"net"
 	"os"
-	"path/filepath"
 	"strings"
 
 	"github.com/kevinburke/ssh_config"
 	"golang.org/x/crypto/ssh"
 	"golang.org/x/crypto/ssh/agent"
 	"golang.org/x/crypto/ssh/knownhosts"
+
+	"github.com/dmacvicar/terraform-provider-libvirt/libvirt/util"
 )
 
 const (
@@ -80,13 +81,7 @@ func (u *ConnectionURI) parseAuthMethods(target string, sshcfg *ssh_config.Confi
 		case "privkey":
 			for _, keypath := range sshKeyPaths {
 				log.Printf("[DEBUG] Reading ssh key '%s'", keypath)
-				path := os.ExpandEnv(keypath)
-				if strings.HasPrefix(path, "~/") {
-					home, err := os.UserHomeDir()
-					if err == nil {
-						path = filepath.Join(home, path[2:])
-					}
-				}
+				path := util.ExpandPath(keypath)
 				sshKey, err := os.ReadFile(path)
 				if err != nil {
 					log.Printf("[ERROR] Failed to read ssh key '%s': %v", keypath, err)
@@ -119,8 +114,8 @@ func (u *ConnectionURI) parseAuthMethods(target string, sshcfg *ssh_config.Confi
 // the ssh configuration file is loaded once and passed along to each host connection.
 func (u *ConnectionURI) dialSSH() (net.Conn, error) {
 	var sshcfg* ssh_config.Config = nil
+	sshConfigFile, err := os.Open(util.ExpandPath(defaultSSHConfigFile))
 
-	sshConfigFile, err := os.Open(os.ExpandEnv(defaultSSHConfigFile))
 	if err != nil {
 		log.Printf("[WARN] Failed to open ssh config file: %v", err)
 	} else {
@@ -221,11 +216,11 @@ func (u *ConnectionURI) dialHost(target string, sshcfg *ssh_config.Config, depth
 		ssh.KeyAlgoECDSA521,
 	}
 	if !skipVerify {
-		kh, err := knownhosts.New(os.ExpandEnv(knownHostsPath))
+		kh, err := knownhosts.New(util.ExpandPath(knownHostsPath))
 		if err != nil {
 			return nil, fmt.Errorf("failed to read ssh known hosts: %w", err)
 		}
-		log.Printf("[DEBUG] Using known hosts file '%s' for target '%s'", os.ExpandEnv(knownHostsPath), target)
+		log.Printf("[DEBUG] Using known hosts file '%s' for target '%s'", util.ExpandPath(knownHostsPath), target)
 
 		hostKeyCallback = func(hostname string, remote net.Addr, key ssh.PublicKey) error {
 			err := kh(net.JoinHostPort(hostName, port), remote, key)

libvirt/util/expandenv.go

@@ -0,0 +1,34 @@
+package util
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+var (
+	userHomeDir = os.UserHomeDir
+	expandEnv   = os.ExpandEnv
+)
+
+// ExpandPath expands environment variables and resolves ~ to the home directory
+// this is a drop-in replacement for os.ExpandEnv but is additionally '~' aware.
+func ExpandPath(path string) string {
+	path = filepath.Clean(expandEnv(path))
+	tilde := filepath.FromSlash("~/")
+
+	// note to maintainers: tilde without a following slash character is simply
+	// interpreted as part of the filename (e.g. ~foo/bar != ~/foo/bar). However,
+	// when running on windows, the filepath will be represented by backslashes ('\'),
+	// therefore we need to convert "~/" to the platform specific format to test for
+	// it, otherwise on windows systems the prefix test will always fail.
+	if strings.HasPrefix(path, tilde) {
+		home, err := userHomeDir()
+		if err != nil {
+			return path // return path as-is if unable to resolve home directory
+		}
+		// Replace ~ with home directory
+		path = filepath.Join(home, strings.TrimPrefix(path, tilde))
+	}
+	return path
+}

libvirt/util/expandenv_test.go

@@ -0,0 +1,32 @@
+package util
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestExpandPath(t *testing.T) {
+	userHomeDir = func() (string, error) {
+		return "/home/mock", nil
+	}
+	expandEnv = func(s string) string {
+		return strings.Replace(s, "${HOME}", "/home/mock", 1)
+	}
+
+
+	assert.Equal(t, filepath.FromSlash("foo/bar/baz"), ExpandPath("foo/bar/baz"))
+	assert.Equal(t, filepath.FromSlash("/home/mock/foo/bar/baz"), ExpandPath("~/foo/bar/baz"))
+	assert.Equal(t, filepath.FromSlash("/home/mock/foo/bar/baz"), ExpandPath("${HOME}/foo/bar/baz"))
+	assert.Equal(t, filepath.FromSlash("~foo/bar/baz"), ExpandPath("~foo/bar/baz"))
+
+	userHomeDir = func() (string, error) {
+		return "", fmt.Errorf("some failure")
+	}
+
+	// failure to get home expansion should leave string unchanged
+	assert.Equal(t, filepath.FromSlash("~/foo/bar/baz"), ExpandPath("~/foo/bar/baz"))
+}