Input validations, help strings, default_user support

builtin/logical/ssh/util.go

@@ -8,7 +8,6 @@ import (
 	"encoding/pem"
 	"fmt"
 	"io"
-	"log"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -16,6 +15,11 @@ import (
 	"golang.org/x/crypto/ssh"
 )
 
+/*
+Executes the command represented by the input.
+Multiple commands can be run by concatinating strings with ';'.
+Currently, it is supported only for linux platforms and user bash shell.
+*/
 func exec_command(cmdString string) error {
 	cmd := exec.Command("/bin/bash", "-c", cmdString)
 	if _, err := cmd.Output(); err != nil {
@@ -24,11 +28,16 @@ func exec_command(cmdString string) error {
 	return nil
 }
 
+/*
+Transfers the file  to the target machine by establishing an SSH session with the target.
+Uses the public key authentication method and hence the parameter 'key' takes in the private key.
+The fileName parameter takes an absolute path.
+*/
 func uploadFileScp(fileName, username, ip, key string) error {
 	nameBase := filepath.Base(fileName)
 	file, err := os.Open(fileName)
 	if err != nil {
-		return fmt.Errorf("Unable to open file")
+		return err
 	}
 	stat, err := file.Stat()
 	if os.IsNotExist(err) {
@@ -36,7 +45,7 @@ func uploadFileScp(fileName, username, ip, key string) error {
 	}
 	session, err := createSSHPublicKeysSession(username, ip, key)
 	if err != nil {
-		return fmt.Errorf("Unable to create SSH Session using public keys: %s", err)
+		return err
 	}
 	if session == nil {
 		return fmt.Errorf("Invalid session object")
@@ -50,12 +59,19 @@ func uploadFileScp(fileName, username, ip, key string) error {
 		w.Close()
 	}()
 	if err := session.Run(fmt.Sprintf("scp -vt %s", nameBase)); err != nil {
-		return fmt.Errorf("Failed to run: %s", err)
+		return err
 	}
 	return nil
 }
 
-func createSSHPublicKeysSession(username string, ipAddr string, hostKey string) (*ssh.Session, error) {
+/*
+Creates a SSH session object which can be used to run commands in the target machine.
+The session will use public key authentication method with port 22.
+*/
+func createSSHPublicKeysSession(username, ipAddr, hostKey string) (*ssh.Session, error) {
+	if username == "" || ipAddr == "" || hostKey == "" {
+		return nil, fmt.Errorf("Invalid parameters")
+	}
 	signer, err := ssh.ParsePrivateKey([]byte(hostKey))
 	if err != nil {
 		return nil, fmt.Errorf("Parsing Private Key failed: %s", err)
@@ -70,7 +86,7 @@ func createSSHPublicKeysSession(username string, ipAddr string, hostKey string)
 
 	client, err := ssh.Dial("tcp", ipAddr+":22", config)
 	if err != nil {
-		return nil, fmt.Errorf("Dial Failed: %s", err)
+		return nil, err
 	}
 	if client == nil {
 		return nil, fmt.Errorf("Invalid client object: %s", err)
@@ -78,35 +94,45 @@ func createSSHPublicKeysSession(username string, ipAddr string, hostKey string)
 
 	session, err := client.NewSession()
 	if err != nil {
-		return nil, fmt.Errorf("Creating new client session failed: %s", err)
+		return nil, err
 	}
 	return session, nil
 }
 
-func removeFile(fileName string) {
+/*
+Deletes the file in the current directory.
+The parameter is just the name of the file and not a path.
+*/
+func removeFile(fileName string) error {
+	if fileName == "" {
+		return fmt.Errorf("Invalid file name")
+	}
 	wd, err := os.Getwd()
 	if err != nil {
-		log.Printf("Error fetching working directory:%s", err)
-		return
+		return err
 	}
 	absFileName := wd + "/" + fileName
 
 	if _, err := os.Stat(absFileName); err == nil {
 		err := os.Remove(absFileName)
 		if err != nil {
-			log.Printf(fmt.Sprintf("Failed: %s", err))
-			return
+			return err
 		}
 	}
+	return nil
 }
 
-func generateRSAKeys() (string, string, error) {
+/*
+Creates a new RSA key pair with key length of 2048.
+The private key will be of pem format and the public key will be of OpenSSH format.
+*/
+func generateRSAKeys() (publicKeyRsa string, privateKeyRsa string, err error) {
 	privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
 	if err != nil {
 		return "", "", fmt.Errorf("error generating RSA key-pair: %s", err)
 	}
 
-	privateKeyRsa := string(pem.EncodeToMemory(&pem.Block{
+	privateKeyRsa = string(pem.EncodeToMemory(&pem.Block{
 		Type:  "RSA PRIVATE KEY",
 		Bytes: x509.MarshalPKCS1PrivateKey(privateKey),
 	}))
@@ -115,10 +141,6 @@ func generateRSAKeys() (string, string, error) {
 	if err != nil {
 		return "", "", fmt.Errorf("error generating RSA key-pair: %s", err)
 	}
-	publicKeyRsa := "ssh-rsa " + base64.StdEncoding.EncodeToString(sshPublicKey.Marshal())
-
-	//ioutil.WriteFile("testkey.pem", []byte(privateKeyRsa), 0600)
-	//ioutil.WriteFile("testkey.pub", []byte(publicKeyRsa), 0600)
-
-	return publicKeyRsa, privateKeyRsa, nil
+	publicKeyRsa = "ssh-rsa " + base64.StdEncoding.EncodeToString(sshPublicKey.Marshal())
+	return
 }