Adds helper files to access config files and generate tls config.

internal/config/files.go

@@ -0,0 +1,26 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+)
+
+var (
+	CAFile         = configFile("ca.pem")
+	ServerCertFile = configFile("server.pem")
+	ServerKeyFile  = configFile("server-key.pem")
+	ClientCertFile = configFile("client.pem")
+	ClientKeyFile  = configFile("client-key.pem")
+)
+
+func configFile(filename string) string {
+	if dir := os.Getenv("CONFIG_DIR"); dir != "" {
+		return filepath.Join(dir, filename)
+	}
+
+	homeDir, err := os.UserHomeDir()
+	if err != nil {
+		panic(err)
+	}
+	return filepath.Join(homeDir, ".proglog", filename)
+}

internal/config/tls.go

@@ -0,0 +1,59 @@
+package config
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"fmt"
+	"io/ioutil"
+)
+
+func SetupTLSConfig(cfg TLSConfig) (*tls.Config, error) {
+	var err error
+	tlsConfig := &tls.Config{}
+	// Load key pair for the server.
+	if cfg.CertFile != "" && cfg.KeyFile != "" {
+		tlsConfig.Certificates = make([]tls.Certificate, 1)
+		tlsConfig.Certificates[0], err = tls.LoadX509KeyPair(
+			cfg.CertFile,
+			cfg.KeyFile,
+		)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if cfg.CAFile != "" {
+		b, err := ioutil.ReadFile(cfg.CAFile)
+		if err != nil {
+			return nil, err
+		}
+		ca := x509.NewCertPool()
+		ok := ca.AppendCertsFromPEM(b)
+		if !ok {
+			return nil, fmt.Errorf(
+				"failed to parse root certificate: %q",
+				cfg.CAFile,
+			)
+		}
+		if cfg.Server {
+			tlsConfig.ClientCAs = ca
+			tlsConfig.ClientAuth = tls.RequireAndVerifyClientCert
+		} else {
+			tlsConfig.RootCAs = ca
+		}
+		tlsConfig.ServerName = cfg.ServerAddress
+	}
+
+	return tlsConfig, nil
+
+}
+
+type TLSConfig struct {
+	CertFile      string
+	KeyFile       string
+	CAFile        string
+	ServerAddress string
+	// If this is true, the server validates the authenticity of client certificates.
+	// Meaning we can use mutual TLS authentication.
+	Server bool
+}