Rename file; use new RNG source with mutex

client.go

@@ -50,10 +50,6 @@ import (
  "golang.org/x/net/idna"
 )
 
-func init() {
- weakrand.Seed(time.Now().UnixNano())
-}
-
 // Client is a high-level API for ACME operations. It wraps
 // a lower-level ACME client with useful functions to make
 // common flows easier, especially for the issuance of
@@ -346,10 +342,12 @@ func (c *Client) getAuthzObjects(ctx context.Context, account acme.Account, orde
  preferredChallenges.addUnique(chal.Type)
  }
  if preferredWasEmpty {
- weakrand.Shuffle(len(preferredChallenges), func(i, j int) {
+ randomSourceMu.Lock()
+ randomSource.Shuffle(len(preferredChallenges), func(i, j int) {
  preferredChallenges[i], preferredChallenges[j] =
  preferredChallenges[j], preferredChallenges[i]
  })
+ randomSourceMu.Unlock()
  }
  preferredChallengesMu.Unlock()
 
@@ -796,9 +794,15 @@ type retryableErr struct{ error }
 
 func (re retryableErr) Unwrap() error { return re.error }
 
-// Keep a list of challenges we've seen offered by servers,
-// and prefer keep an ordered list of
+// Keep a list of challenges we've seen offered by servers, ordered by success rate.
 var (
  preferredChallenges challengeTypes
  preferredChallengesMu sync.Mutex
 )
+
+// Best practice is to avoid the default RNG source and seed our own;
+// custom sources are not safe for concurrent use, hence the mutex.
+var (
+ randomSource = weakrand.New(weakrand.NewSource(time.Now().UnixNano()))
+ randomSourceMu sync.Mutex
+)

certificate_request.go → csr.go

@@ -1,3 +1,17 @@
+// Copyright 2020 Matthew Holt
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package acmez
 
 import (