1 files changed, 112 insertions, 0 deletions
diff --git a/internal/ssh/ssh.go b/internal/ssh/ssh.go
new file mode 100644
index 0000000..77cc341
--- /dev/null
+++ b/internal/ssh/ssh.go
@@ -0,0 +1,112 @@
+package ssh
+
+import (
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"github.com/mimecast/dtail/internal/logger"
+	"encoding/pem"
+	"fmt"
+	"io/ioutil"
+	"net"
+	"os"
+	"syscall"
+
+	gossh "golang.org/x/crypto/ssh"
+	"golang.org/x/crypto/ssh/agent"
+	"golang.org/x/crypto/ssh/terminal"
+)
+
+// GeneratePrivateRSAKey is used by the server to generate its key.
+func GeneratePrivateRSAKey(size int) (*rsa.PrivateKey, error) {
+	privateKey, err := rsa.GenerateKey(rand.Reader, size)
+	if err != nil {
+		return nil, err
+	}
+
+	err = privateKey.Validate()
+	if err != nil {
+		return nil, err
+	}
+
+	return privateKey, nil
+}
+
+// EncodePrivateKeyToPEM is a helper function for converting a key to PEM format.
+func EncodePrivateKeyToPEM(privateKey *rsa.PrivateKey) []byte {
+	derFormat := x509.MarshalPKCS1PrivateKey(privateKey)
+
+	block := pem.Block{
+		Type:    "RSA PRIVATE KEY",
+		Headers: nil,
+		Bytes:   derFormat,
+	}
+
+	return pem.EncodeToMemory(&block)
+}
+
+// Agent used for SSH auth.
+func Agent() (gossh.AuthMethod, error) {
+	sshAgent, err := net.Dial("unix", os.Getenv("SSH_AUTH_SOCK"))
+	if err != nil {
+		return nil, err
+	}
+	agentClient := agent.NewClient(sshAgent)
+	keys, err := agentClient.List()
+	if err != nil {
+		return nil, err
+	}
+	for i, key := range keys {
+		logger.Debug("Public key", i, key)
+	}
+	return gossh.PublicKeysCallback(agentClient.Signers), nil
+}
+
+// EnterKeyPhrase is required to read phrase protected private keys.
+func EnterKeyPhrase(keyFile string) []byte {
+	fmt.Printf("Enter phrase for key %s: ", keyFile)
+	phrase, err := terminal.ReadPassword(int(syscall.Stdin))
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("%s\n", string(phrase))
+	return phrase
+}
+
+// KeyFile returns the key as a SSH auth method.
+func KeyFile(keyFile string) (gossh.AuthMethod, error) {
+	buffer, err := ioutil.ReadFile(keyFile)
+	if err != nil {
+		return nil, err
+	}
+
+	key, err := gossh.ParsePrivateKey(buffer)
+	if err != nil {
+		return nil, err
+	}
+
+	// Key phrase support disabled as password will be printed to stdout!
+	/*
+		if err == nil {
+			return gossh.PublicKeys(key), nil
+		}
+
+		keyPhrase := EnterKeyPhrase(keyFile)
+		key, err = gossh.ParsePrivateKeyWithPassphrase(buffer, keyPhrase)
+		if err != nil {
+			return nil, err
+		}
+	*/
+
+	return gossh.PublicKeys(key), nil
+}
+
+// PrivateKey returns the private key as a SSH auth method.
+func PrivateKey(keyFile string) (gossh.AuthMethod, error) {
+	signer, err := KeyFile(keyFile)
+	if err != nil {
+		logger.Debug(keyFile, err)
+		return nil, err
+	}
+	return gossh.AuthMethod(signer), nil
+}