feat(agent): 增加 HTTPS pin 模式并修复隧道端口竞态

internal/frp/agent_https.go

@@ -0,0 +1,70 @@
+package frp
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/sha256"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/hex"
+	"encoding/pem"
+	"fmt"
+	"math/big"
+	"net"
+	"time"
+)
+
+type agentCertificate struct {
+	CertPEM string
+	KeyPEM  string
+	Pin     string
+}
+
+func generateAgentCertificate(host string) (agentCertificate, error) {
+	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		return agentCertificate{}, err
+	}
+	serialLimit := new(big.Int).Lsh(big.NewInt(1), 128)
+	serial, err := rand.Int(rand.Reader, serialLimit)
+	if err != nil {
+		return agentCertificate{}, err
+	}
+	now := time.Now()
+	template := &x509.Certificate{
+		SerialNumber: serial,
+		Subject:      pkix.Name{CommonName: host},
+		NotBefore:    now.Add(-5 * time.Minute),
+		NotAfter:     now.Add(365 * 24 * time.Hour),
+		KeyUsage:     x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment,
+		ExtKeyUsage:  []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+	}
+	if ip := net.ParseIP(host); ip != nil {
+		template.IPAddresses = []net.IP{ip}
+	} else {
+		template.DNSNames = []string{host}
+	}
+	der, err := x509.CreateCertificate(rand.Reader, template, template, &key.PublicKey, key)
+	if err != nil {
+		return agentCertificate{}, err
+	}
+	keyDER, err := x509.MarshalPKCS8PrivateKey(key)
+	if err != nil {
+		return agentCertificate{}, err
+	}
+	sum := sha256.Sum256(der)
+	return agentCertificate{
+		CertPEM: string(pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der})),
+		KeyPEM:  string(pem.EncodeToMemory(&pem.Block{Type: "PRIVATE KEY", Bytes: keyDER})),
+		Pin:     hex.EncodeToString(sum[:]),
+	}, nil
+}
+
+func validatePin(pin string) error {
+	decoded, err := hex.DecodeString(pin)
+	if err != nil || len(decoded) != sha256.Size {
+		return fmt.Errorf("证书指纹格式无效")
+	}
+	return nil
+}