Knownhosts tilde aware path expansion - fixes #1107

libvirt/uri/ssh.go

@@ -5,13 +5,14 @@
 	"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 @@
 		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.ExpandEnvExt(keypath)
 				sshKey, err := os.ReadFile(path)
 				if err != nil {
 					log.Printf("[ERROR] Failed to read ssh key '%s': %v", keypath, err)
@@ -118,13 +113,12 @@
 // construct the whole ssh connection, which can consist of multiple hops if using proxy jumps,
 // 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.ExpandEnvExt(defaultSSHConfigFile))
 
-	sshConfigFile, err := os.Open(os.ExpandEnv(defaultSSHConfigFile))
 	if err != nil {
 		log.Printf("[WARN] Failed to open ssh config file: %v", err)
 	} else {
 		sshcfg, err = ssh_config.Decode(sshConfigFile)
 		if err != nil {
 			log.Printf("[WARN] Failed to parse ssh config file: '%v' - sshconfig will be ignored.", err)
 		}
@@ -132,7 +126,7 @@
 	}
 
 	// configuration loaded, build tunnel
 	sshClient, err := u.dialHost(u.Host, sshcfg, 0)
 	if err != nil {
 		return nil, err
 	}
@@ -221,11 +215,11 @@
 		ssh.KeyAlgoECDSA521,
 	}
 	if !skipVerify {
-		kh, err := knownhosts.New(os.ExpandEnv(knownHostsPath))
+		kh, err := knownhosts.New(util.ExpandEnvExt(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.ExpandEnvExt(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 +1,27 @@
+package util
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+var (
+	userHomeDir = os.UserHomeDir
+	expandEnv   = os.ExpandEnv
+)
+
+// ExpandEnvExt expands environment variables and resolves ~ to the home directory
+// this is a drop-in replacement for os.ExpandEnv but is additionally '~' aware
+func ExpandEnvExt(path string) string {
+	path = expandEnv(path)
+	if strings.HasPrefix(path, "~/") {
+		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, "~/"))
+	}
+	return path
+}

libvirt/util/expandenv_test.go

@@ -0,0 +1,31 @@
+package util
+
+import (
+	"testing"
+	"strings"
+	"fmt"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestExpandEnvExt(t *testing.T) {
+	userHomeDir = func() (string, error) {
+		return "/home/mock", nil
+	}
+	expandEnv = func(s string) string {
+		return strings.Replace(s, "${HOME}", "/home/mock", 1)
+	}
+
+
+	assert.Equal(t, "foo/bar/baz", ExpandEnvExt("foo/bar/baz"))
+	assert.Equal(t, "/home/mock/foo/bar/baz", ExpandEnvExt("~/foo/bar/baz"))
+	assert.Equal(t, "/home/mock/foo/bar/baz", ExpandEnvExt("${HOME}/foo/bar/baz"))
+	assert.Equal(t, "~foo/bar/baz", ExpandEnvExt("~foo/bar/baz"))
+
+	userHomeDir = func() (string, error) {
+		return "", fmt.Errorf("some failure")
+	}
+
+	// failure to get home expansion should leave string unchanged
+	assert.Equal(t, "~/foo/bar/baz", ExpandEnvExt("~/foo/bar/baz"))
+}