remove deprecated rand.Seed

Suggestion based on go docs of acme autocert.

server/server.go

@@ -26,12 +26,9 @@ package server
 
 import (
 	"context"
-	cryptoRand "crypto/rand"
 	"crypto/tls"
-	"encoding/binary"
 	"errors"
 	"log"
-	"math/rand"
 	"mime"
 	"net/http"
 	_ "net/http/pprof"
@@ -274,9 +271,8 @@ func UseLetsEncrypt(hosts []string) OptionFn {
 			},
 		}
 
-		srvr.tlsConfig = &tls.Config{
-			GetCertificate: m.GetCertificate,
-		}
+		srvr.tlsConfig = m.TLSConfig()
+		srvr.tlsConfig.GetCertificate = m.GetCertificate
 	}
 }
 
@@ -403,14 +399,6 @@ func New(options ...OptionFn) (*Server, error) {
 	return s, nil
 }
 
-func init() {
-	var seedBytes [8]byte
-	if _, err := cryptoRand.Read(seedBytes[:]); err != nil {
-		panic("cannot obtain cryptographically secure seed")
-	}
-	rand.Seed(int64(binary.LittleEndian.Uint64(seedBytes[:])))
-}
-
 // Run starts Server
 func (s *Server) Run() {
 	listening := false

server/token.go

@@ -25,9 +25,22 @@ THE SOFTWARE.
 package server
 
 import (
+	cryptoRand "crypto/rand"
+	"encoding/binary"
 	"math/rand"
 )
 
+var seed *rand.Rand
+
+func init() {
+	var seedBytes [8]byte
+	if _, err := cryptoRand.Read(seedBytes[:]); err != nil {
+		panic("cannot obtain cryptographically secure seed")
+	}
+
+	seed = rand.New(rand.NewSource(int64(binary.LittleEndian.Uint64(seedBytes[:]))))
+}
+
 const (
 	// SYMBOLS characters used for short-urls
 	SYMBOLS = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
@@ -37,7 +50,7 @@ const (
 func token(length int) string {
 	result := ""
 	for i := 0; i < length; i++ {
-		x := rand.Intn(len(SYMBOLS) - 1)
+		x := seed.Intn(len(SYMBOLS) - 1)
 		result = string(SYMBOLS[x]) + result
 	}