From ff729f67553e3406b9f00ec7da73ef24807e44db Mon Sep 17 00:00:00 2001
From: Maycon Santos <mlsmaycon@gmail.com>
Date: Thu, 7 Jul 2022 16:13:46 +0200
Subject: [PATCH] Use id command for user lookup on MacOS (#384)

When building client without CGO, user.Lookup
attempts to get user from /etc/passwd
Which doesn't have the user as MacOS uses
opendirectoryd as user directory
---
 client/ssh/lookup.go        | 10 ++++++++
 client/ssh/lookup_darwin.go | 47 +++++++++++++++++++++++++++++++++++++
 client/ssh/server.go        |  2 +-
 3 files changed, 58 insertions(+), 1 deletion(-)
 create mode 100644 client/ssh/lookup.go
 create mode 100644 client/ssh/lookup_darwin.go

diff --git a/client/ssh/lookup.go b/client/ssh/lookup.go
new file mode 100644
index 000000000..7acef8f0b
--- /dev/null
+++ b/client/ssh/lookup.go
@@ -0,0 +1,10 @@
+//go:build !darwin
+// +build !darwin
+
+package ssh
+
+import "os/user"
+
+func userNameLookup(username string) (*user.User, error) {
+	return user.Lookup(username)
+}
diff --git a/client/ssh/lookup_darwin.go b/client/ssh/lookup_darwin.go
new file mode 100644
index 000000000..e6f3c3b93
--- /dev/null
+++ b/client/ssh/lookup_darwin.go
@@ -0,0 +1,47 @@
+//go:build darwin
+// +build darwin
+
+package ssh
+
+import (
+	"bytes"
+	"fmt"
+	"os/exec"
+	"os/user"
+	"strings"
+)
+
+func userNameLookup(username string) (*user.User, error) {
+	var userObject *user.User
+	userObject, err := user.Lookup(username)
+	if err != nil && err.Error() == user.UnknownUserError(username).Error() {
+		return idUserNameLookup(username)
+	} else if err != nil {
+		return nil, err
+	}
+
+	return userObject, nil
+}
+
+func idUserNameLookup(username string) (*user.User, error) {
+	cmd := exec.Command("id", "-P", username)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return nil, fmt.Errorf("error while retrieving user with id -P command, error: %v", err)
+	}
+	colon := ":"
+
+	if !bytes.Contains(out, []byte(username+colon)) {
+		return nil, fmt.Errorf("unable to find user in returned string")
+	}
+	// netbird:********:501:20::0:0:netbird:/Users/netbird:/bin/zsh
+	parts := strings.SplitN(string(out), colon, 10)
+	userObject := &user.User{
+		Username: parts[0],
+		Uid:      parts[2],
+		Gid:      parts[3],
+		Name:     parts[7],
+		HomeDir:  parts[8],
+	}
+	return userObject, nil
+}
diff --git a/client/ssh/server.go b/client/ssh/server.go
index 70f13e7c4..5d63362b9 100644
--- a/client/ssh/server.go
+++ b/client/ssh/server.go
@@ -137,7 +137,7 @@ func (srv *DefaultServer) sessionHandler(session ssh.Session) {
 		}
 	}()
 
-	localUser, err := user.Lookup(session.User())
+	localUser, err := userNameLookup(session.User())
 	if err != nil {
 		_, err = fmt.Fprintf(session, "remote SSH server couldn't find local user %s\n", session.User()) //nolint
 		err = session.Exit(1)