From 61b484c13b50b0a2f256a1b0f2447511f1568968 Mon Sep 17 00:00:00 2001
From: Aaron Gable <aaron@letsencrypt.org>
Date: Mon, 12 Aug 2024 09:17:09 -0700
Subject: [PATCH] Update to math/rand/v2 (#7657)

Replace all of Boulder's usage of the Go stdlib "math/rand" package with
the newer "math/rand/v2" package which first became available in go1.22.
This package has an improved API and faster performance across the
board.

See https://go.dev/blog/randv2 and https://go.dev/blog/chacha8rand for
details.
---
 bdns/servers.go                       |  7 ++++---
 ca/ca.go                              |  4 ++--
 cmd/cert-checker/main_test.go         |  4 ++--
 cmd/rocsp-tool/client.go              | 14 +++++++-------
 core/util.go                          |  2 +-
 crl/updater/continuous.go             |  4 ++--
 ctpolicy/loglist/loglist.go           |  4 ++--
 grpc/internal/grpcrand/grpcrand.go    |  9 ++++-----
 mocks/sa.go                           |  4 ++--
 ocsp/responder/responder.go           |  4 ++--
 policy/pa.go                          |  4 ++--
 ra/ra_test.go                         |  6 +++---
 ratelimits/limiter_test.go            |  4 ++--
 sa/sa_test.go                         |  4 ++--
 semaphore/semaphore_test.go           |  7 ++++---
 test/ct-test-srv/main.go              |  4 ++--
 test/load-generator/acme/challenge.go |  4 ++--
 test/load-generator/boulder-calls.go  | 12 ++++++------
 va/caa.go                             |  2 +-
 va/http_test.go                       |  4 ++--
 va/va.go                              |  2 +-
 21 files changed, 55 insertions(+), 54 deletions(-)

diff --git a/bdns/servers.go b/bdns/servers.go
index dd8edee98..bfb9d7e0f 100644
--- a/bdns/servers.go
+++ b/bdns/servers.go
@@ -4,15 +4,16 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"math/rand"
+	"math/rand/v2"
 	"net"
 	"strconv"
 	"sync"
 	"time"
 
-	"github.com/letsencrypt/boulder/cmd"
 	"github.com/miekg/dns"
 	"github.com/prometheus/client_golang/prometheus"
+
+	"github.com/letsencrypt/boulder/cmd"
 )
 
 // ServerProvider represents a type which can provide a list of addresses for
@@ -306,7 +307,7 @@ func (dp *dynamicProvider) Addrs() ([]string, error) {
 	var r []string
 	dp.mu.RLock()
 	for ip, ports := range dp.addrs {
-		port := fmt.Sprint(ports[rand.Intn(len(ports))])
+		port := fmt.Sprint(ports[rand.IntN(len(ports))])
 		addr := net.JoinHostPort(ip, port)
 		r = append(r, addr)
 	}
diff --git a/ca/ca.go b/ca/ca.go
index 5eb28eaac..e55b2d665 100644
--- a/ca/ca.go
+++ b/ca/ca.go
@@ -14,7 +14,7 @@ import (
 	"errors"
 	"fmt"
 	"math/big"
-	mrand "math/rand"
+	mrand "math/rand/v2"
 	"strings"
 	"time"
 
@@ -535,7 +535,7 @@ func (ca *certificateAuthorityImpl) issuePrecertificateInner(ctx context.Context
 	if !ok || len(issuerPool) == 0 {
 		return nil, nil, berrors.InternalServerError("no issuers found for public key algorithm %s", csr.PublicKeyAlgorithm)
 	}
-	issuer := issuerPool[mrand.Intn(len(issuerPool))]
+	issuer := issuerPool[mrand.IntN(len(issuerPool))]
 
 	if issuer.Cert.NotAfter.Before(notAfter) {
 		err = berrors.InternalServerError("cannot issue a certificate that expires after the issuer certificate")
diff --git a/cmd/cert-checker/main_test.go b/cmd/cert-checker/main_test.go
index eee0012b0..2a7f7419b 100644
--- a/cmd/cert-checker/main_test.go
+++ b/cmd/cert-checker/main_test.go
@@ -15,7 +15,7 @@ import (
 	"errors"
 	"log"
 	"math/big"
-	mrand "math/rand"
+	mrand "math/rand/v2"
 	"os"
 	"slices"
 	"sort"
@@ -355,7 +355,7 @@ func TestGetAndProcessCerts(t *testing.T) {
 	reg := satest.CreateWorkingRegistration(t, isa.SA{Impl: sa})
 	test.AssertNotError(t, err, "Couldn't create registration")
 	for range 5 {
-		rawCert.SerialNumber = big.NewInt(mrand.Int63())
+		rawCert.SerialNumber = big.NewInt(mrand.Int64())
 		certDER, err := x509.CreateCertificate(rand.Reader, &rawCert, &rawCert, &testKey.PublicKey, testKey)
 		test.AssertNotError(t, err, "Couldn't create certificate")
 		_, err = sa.AddCertificate(context.Background(), &sapb.AddCertificateRequest{
diff --git a/cmd/rocsp-tool/client.go b/cmd/rocsp-tool/client.go
index c70fa30aa..f6e3cb856 100644
--- a/cmd/rocsp-tool/client.go
+++ b/cmd/rocsp-tool/client.go
@@ -3,7 +3,7 @@ package notmain
 import (
 	"context"
 	"fmt"
-	"math/rand"
+	"math/rand/v2"
 	"os"
 	"sync/atomic"
 	"time"
@@ -104,9 +104,9 @@ func (cl *client) loadFromDB(ctx context.Context, speed ProcessingSpeed, startFr
 		if result.err != nil {
 			errorCount++
 			if errorCount < 10 ||
-				(errorCount < 1000 && rand.Intn(1000) < 100) ||
-				(errorCount < 100000 && rand.Intn(1000) < 10) ||
-				(rand.Intn(1000) < 1) {
+				(errorCount < 1000 && rand.IntN(1000) < 100) ||
+				(errorCount < 100000 && rand.IntN(1000) < 10) ||
+				(rand.IntN(1000) < 1) {
 				cl.logger.Errf("error: %s", result.err)
 			}
 		} else {
@@ -115,9 +115,9 @@ func (cl *client) loadFromDB(ctx context.Context, speed ProcessingSpeed, startFr
 
 		total := successCount + errorCount
 		if total < 10 ||
-			(total < 1000 && rand.Intn(1000) < 100) ||
-			(total < 100000 && rand.Intn(1000) < 10) ||
-			(rand.Intn(1000) < 1) {
+			(total < 1000 && rand.IntN(1000) < 100) ||
+			(total < 100000 && rand.IntN(1000) < 10) ||
+			(rand.IntN(1000) < 1) {
 			cl.logger.Infof("stored %d responses, %d errors", successCount, errorCount)
 		}
 	}
diff --git a/core/util.go b/core/util.go
index 36a323530..607b3edbf 100644
--- a/core/util.go
+++ b/core/util.go
@@ -15,7 +15,7 @@ import (
 	"fmt"
 	"io"
 	"math/big"
-	mrand "math/rand"
+	mrand "math/rand/v2"
 	"os"
 	"path"
 	"reflect"
diff --git a/crl/updater/continuous.go b/crl/updater/continuous.go
index e4552f68f..4597fd60a 100644
--- a/crl/updater/continuous.go
+++ b/crl/updater/continuous.go
@@ -2,7 +2,7 @@ package updater
 
 import (
 	"context"
-	"math/rand"
+	"math/rand/v2"
 	"sync"
 	"time"
 
@@ -21,7 +21,7 @@ func (cu *crlUpdater) Run(ctx context.Context) error {
 
 		// Wait for a random number of nanoseconds less than the updatePeriod, so
 		// that process restarts do not skip or delay shards deterministically.
-		waitTimer := time.NewTimer(time.Duration(rand.Int63n(cu.updatePeriod.Nanoseconds())))
+		waitTimer := time.NewTimer(time.Duration(rand.Int64N(cu.updatePeriod.Nanoseconds())))
 		defer waitTimer.Stop()
 		select {
 		case <-waitTimer.C:
diff --git a/ctpolicy/loglist/loglist.go b/ctpolicy/loglist/loglist.go
index 8722b65c8..95cc724a1 100644
--- a/ctpolicy/loglist/loglist.go
+++ b/ctpolicy/loglist/loglist.go
@@ -5,7 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"math/rand"
+	"math/rand/v2"
 	"os"
 	"strings"
 	"time"
@@ -314,6 +314,6 @@ func (ll List) PickOne(operator string, expiry time.Time) (string, string, error
 		return "", "", fmt.Errorf("no log found for group %q and expiry %s", operator, expiry)
 	}
 
-	log := candidates[rand.Intn(len(candidates))]
+	log := candidates[rand.IntN(len(candidates))]
 	return log.Url, log.Key, nil
 }
diff --git a/grpc/internal/grpcrand/grpcrand.go b/grpc/internal/grpcrand/grpcrand.go
index 740f83c2b..f4df37293 100644
--- a/grpc/internal/grpcrand/grpcrand.go
+++ b/grpc/internal/grpcrand/grpcrand.go
@@ -21,13 +21,12 @@
 package grpcrand
 
 import (
-	"math/rand"
+	"math/rand/v2"
 	"sync"
-	"time"
 )
 
 var (
-	r  = rand.New(rand.NewSource(time.Now().UnixNano()))
+	r  = rand.New(rand.NewPCG(rand.Uint64(), rand.Uint64()))
 	mu sync.Mutex
 )
 
@@ -42,14 +41,14 @@ func Int() int {
 func Int63n(n int64) int64 {
 	mu.Lock()
 	defer mu.Unlock()
-	return r.Int63n(n)
+	return r.Int64N(n)
 }
 
 // Intn implements rand.Intn on the grpcrand global source.
 func Intn(n int) int {
 	mu.Lock()
 	defer mu.Unlock()
-	return r.Intn(n)
+	return r.IntN(n)
 }
 
 // Float64 implements rand.Float64 on the grpcrand global source.
diff --git a/mocks/sa.go b/mocks/sa.go
index 511fcef7a..bbbb65cc9 100644
--- a/mocks/sa.go
+++ b/mocks/sa.go
@@ -6,7 +6,7 @@ import (
 	"crypto/x509"
 	"errors"
 	"fmt"
-	"math/rand"
+	"math/rand/v2"
 	"net"
 	"os"
 	"time"
@@ -353,7 +353,7 @@ func (sa *StorageAuthority) NewOrderAndAuthzs(_ context.Context, req *sapb.NewOr
 		Names:            req.NewOrder.Names,
 		V2Authorizations: req.NewOrder.V2Authorizations,
 		// Mock new fields generated by the database transaction.
-		Id:      rand.Int63(),
+		Id:      rand.Int64(),
 		Created: timestamppb.Now(),
 		// A new order is never processing because it can't have been finalized yet.
 		BeganProcessing:        false,
diff --git a/ocsp/responder/responder.go b/ocsp/responder/responder.go
index 5fc273644..d985e92ef 100644
--- a/ocsp/responder/responder.go
+++ b/ocsp/responder/responder.go
@@ -40,7 +40,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"math/rand"
+	"math/rand/v2"
 	"net/http"
 	"net/url"
 	"time"
@@ -153,7 +153,7 @@ var hashToString = map[crypto.Hash]string{
 }
 
 func SampledError(log blog.Logger, sampleRate int, format string, a ...interface{}) {
-	if sampleRate > 0 && rand.Intn(sampleRate) == 0 {
+	if sampleRate > 0 && rand.IntN(sampleRate) == 0 {
 		log.Errf(format, a...)
 	}
 }
diff --git a/policy/pa.go b/policy/pa.go
index ce7857a7d..2e7981518 100644
--- a/policy/pa.go
+++ b/policy/pa.go
@@ -5,7 +5,7 @@ import (
 	"encoding/hex"
 	"errors"
 	"fmt"
-	"math/rand"
+	"math/rand/v2"
 	"net"
 	"net/mail"
 	"os"
@@ -46,7 +46,7 @@ func New(challengeTypes map[core.AcmeChallenge]bool, log blog.Logger) (*Authorit
 		log:               log,
 		enabledChallenges: challengeTypes,
 		// We don't need real randomness for this.
-		pseudoRNG: rand.New(rand.NewSource(99)),
+		pseudoRNG: rand.New(rand.NewPCG(rand.Uint64(), rand.Uint64())),
 	}
 
 	return &pa, nil
diff --git a/ra/ra_test.go b/ra/ra_test.go
index b09a76a86..f9d6782db 100644
--- a/ra/ra_test.go
+++ b/ra/ra_test.go
@@ -15,7 +15,7 @@ import (
 	"errors"
 	"fmt"
 	"math/big"
-	mrand "math/rand"
+	mrand "math/rand/v2"
 	"net"
 	"os"
 	"regexp"
@@ -2401,7 +2401,7 @@ func (msa *mockSAWithAuthzs) GetAuthorizations2(ctx context.Context, req *sapb.G
 func (msa *mockSAWithAuthzs) NewOrderAndAuthzs(ctx context.Context, req *sapb.NewOrderAndAuthzsRequest, _ ...grpc.CallOption) (*corepb.Order, error) {
 	authzIDs := req.NewOrder.V2Authorizations
 	for range req.NewAuthzs {
-		authzIDs = append(authzIDs, mrand.Int63())
+		authzIDs = append(authzIDs, mrand.Int64())
 	}
 	return &corepb.Order{
 		// Fields from the input new order request.
@@ -2411,7 +2411,7 @@ func (msa *mockSAWithAuthzs) NewOrderAndAuthzs(ctx context.Context, req *sapb.Ne
 		V2Authorizations:       authzIDs,
 		CertificateProfileName: req.NewOrder.CertificateProfileName,
 		// Mock new fields generated by the database transaction.
-		Id:      mrand.Int63(),
+		Id:      mrand.Int64(),
 		Created: timestamppb.Now(),
 		// A new order is never processing because it can't have been finalized yet.
 		BeganProcessing: false,
diff --git a/ratelimits/limiter_test.go b/ratelimits/limiter_test.go
index efec45432..62f927bdd 100644
--- a/ratelimits/limiter_test.go
+++ b/ratelimits/limiter_test.go
@@ -2,7 +2,7 @@ package ratelimits
 
 import (
 	"context"
-	"math/rand"
+	"math/rand/v2"
 	"net"
 	"testing"
 	"time"
@@ -43,7 +43,7 @@ func setup(t *testing.T) (context.Context, map[string]*Limiter, *TransactionBuil
 	// runs.
 	randIP := make(net.IP, 4)
 	for i := range 4 {
-		randIP[i] = byte(rand.Intn(256))
+		randIP[i] = byte(rand.IntN(256))
 	}
 
 	// Construct a limiter for each source.
diff --git a/sa/sa_test.go b/sa/sa_test.go
index 10991d412..626a27d74 100644
--- a/sa/sa_test.go
+++ b/sa/sa_test.go
@@ -14,7 +14,7 @@ import (
 	"fmt"
 	"math/big"
 	"math/bits"
-	mrand "math/rand"
+	mrand "math/rand/v2"
 	"net"
 	"os"
 	"reflect"
@@ -3358,7 +3358,7 @@ func TestSerialsForIncident(t *testing.T) {
 		"1335": true, "1336": true, "1337": true, "1338": true,
 	}
 	for i := range expectedSerials {
-		randInt := func() int64 { return mrand.Int63() }
+		randInt := func() int64 { return mrand.Int64() }
 		_, err := testIncidentsDbMap.ExecContext(ctx,
 			fmt.Sprintf("INSERT INTO incident_foo (%s) VALUES ('%s', %d, %d, '%s')",
 				"serial, registrationID, orderID, lastNoticeSent",
diff --git a/semaphore/semaphore_test.go b/semaphore/semaphore_test.go
index 71a5d2340..976491b73 100644
--- a/semaphore/semaphore_test.go
+++ b/semaphore/semaphore_test.go
@@ -6,14 +6,15 @@ package semaphore_test
 
 import (
 	"context"
-	"math/rand"
+	"math/rand/v2"
 	"runtime"
 	"sync"
 	"testing"
 	"time"
 
-	"github.com/letsencrypt/boulder/semaphore"
 	"golang.org/x/sync/errgroup"
+
+	"github.com/letsencrypt/boulder/semaphore"
 )
 
 const maxSleep = 1 * time.Millisecond
@@ -21,7 +22,7 @@ const maxSleep = 1 * time.Millisecond
 func HammerWeighted(sem *semaphore.Weighted, n int64, loops int) {
 	for i := 0; i < loops; i++ {
 		_ = sem.Acquire(context.Background(), n)
-		time.Sleep(time.Duration(rand.Int63n(int64(maxSleep/time.Nanosecond))) * time.Nanosecond)
+		time.Sleep(time.Duration(rand.Int64N(int64(maxSleep/time.Nanosecond))) * time.Nanosecond)
 		sem.Release(n)
 	}
 }
diff --git a/test/ct-test-srv/main.go b/test/ct-test-srv/main.go
index 564ad85f7..eb7c4bc81 100644
--- a/test/ct-test-srv/main.go
+++ b/test/ct-test-srv/main.go
@@ -13,7 +13,7 @@ import (
 	"fmt"
 	"io"
 	"log"
-	"math/rand"
+	"math/rand/v2"
 	"net/http"
 	"os"
 	"strings"
@@ -161,7 +161,7 @@ func (is *integrationSrv) addChainOrPre(w http.ResponseWriter, r *http.Request,
 	is.submissions[hostnames]++
 	is.Unlock()
 
-	if is.flakinessRate != 0 && rand.Intn(100) < is.flakinessRate {
+	if is.flakinessRate != 0 && rand.IntN(100) < is.flakinessRate {
 		time.Sleep(10 * time.Second)
 	}
 
diff --git a/test/load-generator/acme/challenge.go b/test/load-generator/acme/challenge.go
index 47e8d861d..12aeb9aa2 100644
--- a/test/load-generator/acme/challenge.go
+++ b/test/load-generator/acme/challenge.go
@@ -3,7 +3,7 @@ package acme
 import (
 	"errors"
 	"fmt"
-	mrand "math/rand"
+	mrand "math/rand/v2"
 	"strings"
 
 	"github.com/letsencrypt/boulder/core"
@@ -67,7 +67,7 @@ func (strategy randomChallengeStrategy) PickChallenge(authz *core.Authorization)
 	if len(authz.Challenges) == 0 {
 		return nil, ErrPickChallengeAuthzMissingChallenges
 	}
-	return &authz.Challenges[mrand.Intn(len(authz.Challenges))], nil
+	return &authz.Challenges[mrand.IntN(len(authz.Challenges))], nil
 }
 
 // preferredTypeChallengeStrategy is a ChallengeStrategy implementation that
diff --git a/test/load-generator/boulder-calls.go b/test/load-generator/boulder-calls.go
index 8f98cade3..351c551f0 100644
--- a/test/load-generator/boulder-calls.go
+++ b/test/load-generator/boulder-calls.go
@@ -16,7 +16,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	mrand "math/rand"
+	mrand "math/rand/v2"
 	"net/http"
 	"time"
 
@@ -72,7 +72,7 @@ func getAccount(s *State, c *acmeCache) error {
 	}
 
 	// Select a random account from the state and put it into the context
-	c.acct = s.accts[mrand.Intn(len(s.accts))]
+	c.acct = s.accts[mrand.IntN(len(s.accts))]
 	c.ns = &nonceSource{s: s}
 	return nil
 }
@@ -164,7 +164,7 @@ func randDomain(base string) string {
 func newOrder(s *State, c *acmeCache) error {
 	// Pick a random number of names within the constraints of the maxNamesPerCert
 	// parameter
-	orderSize := 1 + mrand.Intn(s.maxNamesPerCert-1)
+	orderSize := 1 + mrand.IntN(s.maxNamesPerCert-1)
 	// Generate that many random domain names. There may be some duplicates, we
 	// don't care. The ACME server will collapse those down for us, how handy!
 	dnsNames := []identifier.ACMEIdentifier{}
@@ -231,7 +231,7 @@ func newOrder(s *State, c *acmeCache) error {
 // popPendingOrder *removes* a random pendingOrder from the context, returning
 // it.
 func popPendingOrder(c *acmeCache) *OrderJSON {
-	orderIndex := mrand.Intn(len(c.pendingOrders))
+	orderIndex := mrand.IntN(len(c.pendingOrders))
 	order := c.pendingOrders[orderIndex]
 	c.pendingOrders = append(c.pendingOrders[:orderIndex], c.pendingOrders[orderIndex+1:]...)
 	return order
@@ -465,7 +465,7 @@ func pollOrderForCert(order *OrderJSON, s *State, c *acmeCache) (*OrderJSON, err
 // popFulfilledOrder **removes** a fulfilled order from the context, returning
 // it. Fulfilled orders have all of their authorizations satisfied.
 func popFulfilledOrder(c *acmeCache) string {
-	orderIndex := mrand.Intn(len(c.fulfilledOrders))
+	orderIndex := mrand.IntN(len(c.fulfilledOrders))
 	order := c.fulfilledOrders[orderIndex]
 	c.fulfilledOrders = append(c.fulfilledOrders[:orderIndex], c.fulfilledOrders[orderIndex+1:]...)
 	return order
@@ -580,7 +580,7 @@ func postAsGet(s *State, c *acmeCache, url string, latencyTag string) (*http.Res
 }
 
 func popCertificate(c *acmeCache) string {
-	certIndex := mrand.Intn(len(c.certs))
+	certIndex := mrand.IntN(len(c.certs))
 	certURL := c.certs[certIndex]
 	c.certs = append(c.certs[:certIndex], c.certs[certIndex+1:]...)
 	return certURL
diff --git a/va/caa.go b/va/caa.go
index b4703b6af..5c235bef4 100644
--- a/va/caa.go
+++ b/va/caa.go
@@ -3,7 +3,7 @@ package va
 import (
 	"context"
 	"fmt"
-	"math/rand"
+	"math/rand/v2"
 	"net/url"
 	"regexp"
 	"strings"
diff --git a/va/http_test.go b/va/http_test.go
index 038803539..92e17db66 100644
--- a/va/http_test.go
+++ b/va/http_test.go
@@ -6,7 +6,7 @@ import (
 	"encoding/base64"
 	"errors"
 	"fmt"
-	mrand "math/rand"
+	mrand "math/rand/v2"
 	"net"
 	"net/http"
 	"net/http/httptest"
@@ -1213,7 +1213,7 @@ func TestHTTPBadPort(t *testing.T) {
 	// Pick a random port between 40000 and 65000 - with great certainty we won't
 	// have an HTTP server listening on this port and the test will fail as
 	// intended
-	badPort := 40000 + mrand.Intn(25000)
+	badPort := 40000 + mrand.IntN(25000)
 	va.httpPort = badPort
 
 	_, err := va.validateHTTP01(ctx, dnsi("localhost"), expectedToken, expectedKeyAuthorization)
diff --git a/va/va.go b/va/va.go
index c935f8d25..097c39d1c 100644
--- a/va/va.go
+++ b/va/va.go
@@ -7,7 +7,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"math/rand"
+	"math/rand/v2"
 	"net"
 	"net/url"
 	"os"