uploader: use the TOML config file infrastructure, too. (#439)

* Make uploader use the TOML config file intrastructure, too.

* Improve method naming a bit.

* Improve method naming a bit.

* Add forgotten struct tags for TOML

* Add version to command line only parameters in uploader documentation

* Be explicit about supported options in config file.

* allow interactive flags in config file.

---------

Co-authored-by: JanHoefelmeyer <Jan Höfelmeyer jhoefelmeyer@intevation.de>

cmd/csaf_uploader/config.go

@@ -0,0 +1,190 @@
+// This file is Free Software under the MIT License
+// without warranty, see README.md and LICENSES/MIT.txt for details.
+//
+// SPDX-License-Identifier: MIT
+//
+// SPDX-FileCopyrightText: 2023 German Federal Office for Information Security (BSI) <https://www.bsi.bund.de>
+// Software-Engineering: 2023 Intevation GmbH <https://intevation.de>
+
+package main
+
+import (
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"os"
+
+	"github.com/ProtonMail/gopenpgp/v2/crypto"
+	"github.com/csaf-poc/csaf_distribution/v2/internal/certs"
+	"github.com/csaf-poc/csaf_distribution/v2/internal/options"
+	"golang.org/x/crypto/bcrypt"
+	"golang.org/x/term"
+)
+
+const (
+	defaultURL    = "https://localhost/cgi-bin/csaf_provider.go"
+	defaultAction = "upload"
+	defaultTLP    = "csaf"
+)
+
+// The supported flag config of the uploader command line
+type config struct {
+	//lint:ignore SA5008 We are using choice twice: upload, create.
+	Action string `short:"a" long:"action" choice:"upload" choice:"create" description:"Action to perform" toml:"action"`
+	URL    string `short:"u" long:"url" description:"URL of the CSAF provider" value-name:"URL" toml:"url"`
+	//lint:ignore SA5008 We are using choice many times: csaf, white, green, amber, red.
+	TLP            string `short:"t" long:"tlp" choice:"csaf" choice:"white" choice:"green" choice:"amber" choice:"red" description:"TLP of the feed" toml:"tlp"`
+	ExternalSigned bool   `short:"x" long:"external-signed" description:"CSAF files are signed externally. Assumes .asc files beside CSAF files." toml:"external_signed"`
+	NoSchemaCheck  bool   `short:"s" long:"no-schema-check" description:"Do not check files against CSAF JSON schema locally." toml:"no_schema_check"`
+
+	Key              *string `short:"k" long:"key" description:"OpenPGP key to sign the CSAF files" value-name:"KEY-FILE" toml:"key"`
+	Password         *string `short:"p" long:"password" description:"Authentication password for accessing the CSAF provider" value-name:"PASSWORD" toml:"password"`
+	Passphrase       *string `short:"P" long:"passphrase" description:"Passphrase to unlock the OpenPGP key" value-name:"PASSPHRASE" toml:"passphrase"`
+	ClientCert       *string `long:"client-cert" description:"TLS client certificate file (PEM encoded data)" value-name:"CERT-FILE.crt" toml:"client_cert"`
+	ClientKey        *string `long:"client-key" description:"TLS client private key file (PEM encoded data)" value-name:"KEY-FILE.pem" toml:"client_key"`
+	ClientPassphrase *string `long:"client-passphrase" description:"Optional passphrase for the client cert (limited, experimental, see downloader doc)" value-name:"PASSPHRASE" toml:"client_passphrase"`
+
+	PasswordInteractive   bool `short:"i" long:"password-interactive" description:"Enter password interactively" toml:"password_interactive"`
+	PassphraseInteractive bool `short:"I" long:"passphrase-interactive" description:"Enter OpenPGP key passphrase interactively" toml:"passphrase_interactive"`
+
+	Insecure bool `long:"insecure" description:"Do not check TLS certificates from provider" toml:"insecure"`
+
+	Config  string `short:"c" long:"config" description:"Path to config TOML file" value-name:"TOML-FILE" toml:"-"`
+	Version bool   `long:"version" description:"Display version of the binary" toml:"-"`
+
+	clientCerts []tls.Certificate
+	cachedAuth  string
+	keyRing     *crypto.KeyRing
+}
+
+// iniPaths are the potential file locations of the the config file.
+var configPaths = []string{
+	"~/.config/csaf/uploader.toml",
+	"~/.csaf_uploader.toml",
+	"csaf_uploader.toml",
+}
+
+// parseArgsConfig parses the command line and if need a config file.
+func parseArgsConfig() ([]string, *config, error) {
+	p := options.Parser[config]{
+		DefaultConfigLocations: configPaths,
+		ConfigLocation:         func(cfg *config) string { return cfg.Config },
+		Usage:                  "[OPTIONS] advisories...",
+		HasVersion:             func(cfg *config) bool { return cfg.Version },
+		SetDefaults: func(cfg *config) {
+			cfg.URL = defaultURL
+			cfg.Action = defaultAction
+			cfg.TLP = defaultTLP
+		},
+		// Re-establish default values if not set.
+		EnsureDefaults: func(cfg *config) {
+			if cfg.URL == "" {
+				cfg.URL = defaultURL
+			}
+			if cfg.Action == "" {
+				cfg.Action = defaultAction
+			}
+			if cfg.TLP == "" {
+				cfg.TLP = defaultTLP
+			}
+		},
+	}
+	return p.Parse()
+}
+
+// prepareCertificates loads the client side certificates used by the HTTP client.
+func (cfg *config) prepareCertificates() error {
+	cert, err := certs.LoadCertificate(
+		cfg.ClientCert, cfg.ClientKey, cfg.ClientPassphrase)
+	if err != nil {
+		return err
+	}
+	cfg.clientCerts = cert
+	return nil
+}
+
+// readInteractive prints a message to command line and retrieves the password from it.
+func readInteractive(prompt string, pw **string) error {
+	fmt.Print(prompt)
+	p, err := term.ReadPassword(int(os.Stdin.Fd()))
+	if err != nil {
+		return err
+	}
+	ps := string(p)
+	*pw = &ps
+	return nil
+}
+
+// prepareInteractive prompts for interactive passwords.
+func (cfg *config) prepareInteractive() error {
+	if cfg.PasswordInteractive {
+		if err := readInteractive("Enter auth password: ", &cfg.Password); err != nil {
+			return err
+		}
+	}
+	if cfg.PassphraseInteractive {
+		if err := readInteractive("Enter OpenPGP passphrase: ", &cfg.Passphrase); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// loadOpenPGPKey loads an OpenPGP key.
+func loadOpenPGPKey(filename string) (*crypto.Key, error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	return crypto.NewKeyFromArmoredReader(f)
+}
+
+// prepareOpenPGPKey loads the configured OpenPGP key.
+func (cfg *config) prepareOpenPGPKey() error {
+	if cfg.Action != "upload" || cfg.Key == nil {
+		return nil
+	}
+	if cfg.ExternalSigned {
+		return errors.New("refused to sign external signed files")
+	}
+	key, err := loadOpenPGPKey(*cfg.Key)
+	if err != nil {
+		return err
+	}
+	if cfg.Passphrase != nil {
+		if key, err = key.Unlock([]byte(*cfg.Passphrase)); err != nil {
+			return err
+		}
+	}
+	cfg.keyRing, err = crypto.NewKeyRing(key)
+	return err
+}
+
+// preparePassword pre-calculates the auth header.
+func (cfg *config) preparePassword() error {
+	if cfg.Password != nil {
+		hash, err := bcrypt.GenerateFromPassword(
+			[]byte(*cfg.Password), bcrypt.DefaultCost)
+		if err != nil {
+			return err
+		}
+		cfg.cachedAuth = string(hash)
+	}
+	return nil
+}
+
+// prepare prepares internal state of a loaded configuration.
+func (cfg *config) prepare() error {
+	for _, prepare := range []func(*config) error{
+		(*config).prepareCertificates,
+		(*config).prepareInteractive,
+		(*config).prepareOpenPGPKey,
+		(*config).preparePassword,
+	} {
+		if err := prepare(cfg); err != nil {
+			return err
+		}
+	}
+	return nil
+}