🎨 Implement HTTPS network serving (#16912)

* Add use TLS for network serving configuration option

* kernel: Implement TLS certificate generation

* kernel: server: Use https for fixed port proxy when needed

* Allow exporting the CA Certificate file

* Implement import and export of CA Certs

kernel/util/cert.go

@@ -0,0 +1,337 @@
+// SiYuan - Refactor your thinking
+// Copyright (c) 2020-present, b3log.org
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package util
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"fmt"
+	"math/big"
+	"net"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/88250/gulu"
+	"github.com/siyuan-note/logging"
+)
+
+const (
+	TLSCACertFilename = "ca.crt"
+	TLSCAKeyFilename  = "ca.key"
+	TLSCertFilename   = "cert.pem"
+	TLSKeyFilename    = "key.pem"
+)
+
+// Returns paths to existing TLS certificates or generates new ones signed by a local CA.
+// Certificates are stored in the conf directory of the workspace.
+func GetOrCreateTLSCert() (certPath, keyPath string, err error) {
+	certPath = filepath.Join(ConfDir, TLSCertFilename)
+	keyPath = filepath.Join(ConfDir, TLSKeyFilename)
+	caCertPath := filepath.Join(ConfDir, TLSCACertFilename)
+	caKeyPath := filepath.Join(ConfDir, TLSCAKeyFilename)
+
+	if !gulu.File.IsExist(caCertPath) || !gulu.File.IsExist(caKeyPath) {
+		logging.LogInfof("generating local CA for TLS...")
+		if err = generateCACert(caCertPath, caKeyPath); err != nil {
+			logging.LogErrorf("failed to generate CA certificates: %s", err)
+			return "", "", err
+		}
+	}
+
+	if gulu.File.IsExist(certPath) && gulu.File.IsExist(keyPath) {
+		if validateCert(certPath) {
+			logging.LogInfof("using existing TLS certificates from [%s]", ConfDir)
+			return certPath, keyPath, nil
+		}
+		logging.LogInfof("existing TLS certificates are invalid or expired, regenerating...")
+	}
+
+	caCert, caKey, err := loadCA(caCertPath, caKeyPath)
+	if err != nil {
+		logging.LogErrorf("failed to load CA certificates: %s", err)
+		return "", "", err
+	}
+
+	logging.LogInfof("generating TLS server certificates signed by local CA...")
+	if err = generateServerCert(certPath, keyPath, caCert, caKey); err != nil {
+		logging.LogErrorf("failed to generate TLS certificates: %s", err)
+		return "", "", err
+	}
+
+	logging.LogInfof("generated TLS certificates at [%s]", ConfDir)
+	return certPath, keyPath, nil
+}
+
+// Checks if the certificate file exists, is not expired, and contains all current IP addresses
+func validateCert(certPath string) bool {
+	certPEM, err := os.ReadFile(certPath)
+	if err != nil {
+		return false
+	}
+
+	block, _ := pem.Decode(certPEM)
+	if block == nil {
+		return false
+	}
+
+	cert, err := x509.ParseCertificate(block.Bytes)
+	if err != nil {
+		return false
+	}
+
+	// Check if certificate is still valid, with 7 day buffer
+	if !time.Now().Add(7 * 24 * time.Hour).Before(cert.NotAfter) {
+		return false
+	}
+
+	// Check if certificate contains all current IP addresses
+	currentIPs := GetServerAddrs()
+	certIPMap := make(map[string]bool)
+	for _, ip := range cert.IPAddresses {
+		certIPMap[ip.String()] = true
+	}
+
+	for _, ipStr := range currentIPs {
+		ipStr = trimIPv6Brackets(ipStr)
+		ip := net.ParseIP(ipStr)
+		if ip == nil {
+			continue
+		}
+
+		if !certIPMap[ip.String()] {
+			logging.LogInfof("certificate missing current IP address [%s], will regenerate", ip.String())
+			return false
+		}
+	}
+
+	return true
+}
+
+// Creates a new self-signed CA certificate
+func generateCACert(certPath, keyPath string) error {
+	privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		return err
+	}
+
+	serialNumber, err := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 128))
+	if err != nil {
+		return err
+	}
+
+	notBefore := time.Now()
+	notAfter := notBefore.Add(10 * 365 * 24 * time.Hour)
+
+	template := x509.Certificate{
+		SerialNumber: serialNumber,
+		Subject: pkix.Name{
+			Organization: []string{"SiYuan"},
+			CommonName:   "SiYuan Local CA",
+		},
+		NotBefore:             notBefore,
+		NotAfter:              notAfter,
+		KeyUsage:              x509.KeyUsageCertSign | x509.KeyUsageCRLSign,
+		BasicConstraintsValid: true,
+		IsCA:                  true,
+	}
+
+	certDER, err := x509.CreateCertificate(rand.Reader, &template, &template, &privateKey.PublicKey, privateKey)
+	if err != nil {
+		return err
+	}
+
+	return writeCertAndKey(certPath, keyPath, certDER, privateKey)
+}
+
+// Creates a new server certificate signed by the CA
+func generateServerCert(certPath, keyPath string, caCert *x509.Certificate, caKey any) error {
+	privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		return err
+	}
+
+	serialNumber, err := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 128))
+	if err != nil {
+		return err
+	}
+
+	notBefore := time.Now()
+	notAfter := notBefore.Add(365 * 24 * time.Hour)
+
+	ipAddresses := []net.IP{
+		net.ParseIP("127.0.0.1"),
+		net.IPv6loopback,
+	}
+
+	localIPs := GetServerAddrs()
+	for _, ipStr := range localIPs {
+		ipStr = trimIPv6Brackets(ipStr)
+		if ip := net.ParseIP(ipStr); ip != nil {
+			ipAddresses = append(ipAddresses, ip)
+		}
+	}
+
+	template := x509.Certificate{
+		SerialNumber: serialNumber,
+		Subject: pkix.Name{
+			Organization: []string{"SiYuan"},
+			CommonName:   "SiYuan Local Server",
+		},
+		NotBefore:             notBefore,
+		NotAfter:              notAfter,
+		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+		DNSNames:              []string{"localhost"},
+		IPAddresses:           ipAddresses,
+	}
+
+	certDER, err := x509.CreateCertificate(rand.Reader, &template, caCert, &privateKey.PublicKey, caKey)
+	if err != nil {
+		return err
+	}
+
+	return writeCertAndKey(certPath, keyPath, certDER, privateKey)
+}
+
+// Loads the CA certificate and private key from files
+func loadCA(certPath, keyPath string) (*x509.Certificate, any, error) {
+	certPEM, err := os.ReadFile(certPath)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	block, _ := pem.Decode(certPEM)
+	if block == nil {
+		return nil, nil, fmt.Errorf("failed to decode CA certificate PEM")
+	}
+
+	caCert, err := x509.ParseCertificate(block.Bytes)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	keyPEM, err := os.ReadFile(keyPath)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	block, _ = pem.Decode(keyPEM)
+	if block == nil {
+		return nil, nil, fmt.Errorf("failed to decode CA key PEM")
+	}
+
+	caKey, err := x509.ParseECPrivateKey(block.Bytes)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return caCert, caKey, nil
+}
+
+func writeCertAndKey(certPath, keyPath string, certDER []byte, privateKey *ecdsa.PrivateKey) error {
+	certFile, err := os.Create(certPath)
+	if err != nil {
+		return err
+	}
+	defer certFile.Close()
+
+	if err = pem.Encode(certFile, &pem.Block{Type: "CERTIFICATE", Bytes: certDER}); err != nil {
+		return err
+	}
+
+	keyFile, err := os.Create(keyPath)
+	if err != nil {
+		return err
+	}
+	defer keyFile.Close()
+
+	keyDER, err := x509.MarshalECPrivateKey(privateKey)
+	if err != nil {
+		return err
+	}
+
+	if err = pem.Encode(keyFile, &pem.Block{Type: "EC PRIVATE KEY", Bytes: keyDER}); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Imports a CA certificate and private key from PEM-encoded strings.
+func ImportCABundle(caCertPEM, caKeyPEM string) error {
+	certBlock, _ := pem.Decode([]byte(caCertPEM))
+	if certBlock == nil {
+		return fmt.Errorf("failed to decode CA certificate PEM")
+	}
+
+	caCert, err := x509.ParseCertificate(certBlock.Bytes)
+	if err != nil {
+		return fmt.Errorf("failed to parse CA certificate: %w", err)
+	}
+
+	if !caCert.IsCA {
+		return fmt.Errorf("the provided certificate is not a CA certificate")
+	}
+
+	keyBlock, _ := pem.Decode([]byte(caKeyPEM))
+	if keyBlock == nil {
+		return fmt.Errorf("failed to decode CA private key PEM")
+	}
+
+	_, err = x509.ParseECPrivateKey(keyBlock.Bytes)
+	if err != nil {
+		return fmt.Errorf("failed to parse CA private key: %w", err)
+	}
+
+	caCertPath := filepath.Join(ConfDir, TLSCACertFilename)
+	caKeyPath := filepath.Join(ConfDir, TLSCAKeyFilename)
+
+	if err := os.WriteFile(caCertPath, []byte(caCertPEM), 0644); err != nil {
+		return fmt.Errorf("failed to write CA certificate: %w", err)
+	}
+
+	if err := os.WriteFile(caKeyPath, []byte(caKeyPEM), 0600); err != nil {
+		return fmt.Errorf("failed to write CA private key: %w", err)
+	}
+
+	certPath := filepath.Join(ConfDir, TLSCertFilename)
+	keyPath := filepath.Join(ConfDir, TLSKeyFilename)
+
+	if gulu.File.IsExist(certPath) {
+		os.Remove(certPath)
+	}
+	if gulu.File.IsExist(keyPath) {
+		os.Remove(keyPath)
+	}
+
+	logging.LogInfof("imported CA bundle, server certificate will be regenerated on next TLS initialization")
+	return nil
+}
+
+// trimIPv6Brackets removes brackets from IPv6 address strings like "[::1]"
+func trimIPv6Brackets(ip string) string {
+	if len(ip) > 2 && ip[0] == '[' && ip[len(ip)-1] == ']' {
+		return ip[1 : len(ip)-1]
+	}
+	return ip
+}