From b1f9139ca50ddeb88d395dca2021ab1bdade20b6 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 26 Aug 2022 10:39:18 +0530
Subject: [PATCH] Use a fully random async_id rather than a uuid

---
 tools/cmd/at/template.go       |  2 +-
 tools/utils/short-uuid.go      | 17 +++++++++++++++++
 tools/utils/short-uuid_test.go |  4 ++--
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/tools/cmd/at/template.go b/tools/cmd/at/template.go
index 6b58983a0..ef4bc7e86 100644
--- a/tools/cmd/at/template.go
+++ b/tools/cmd/at/template.go
@@ -39,7 +39,7 @@ func create_rc_CMD_NAME(args []string) (*utils.RemoteControlCmd, error) {
 		NoResponse: NO_RESPONSE_BASE,
 	}
 	if IS_ASYNC {
-		async_id, err := utils.HumanUUID4()
+		async_id, err := utils.HumanRandomId(128)
 		if err != nil {
 			return nil, err
 		}
diff --git a/tools/utils/short-uuid.go b/tools/utils/short-uuid.go
index 7f1eb074b..ebdd43b6b 100644
--- a/tools/utils/short-uuid.go
+++ b/tools/utils/short-uuid.go
@@ -3,6 +3,7 @@
 package utils
 
 import (
+	"crypto/rand"
 	"math"
 	"math/big"
 
@@ -70,6 +71,15 @@ func CreateShortUUID(alphabet string) *ShortUUID {
 	return &ans
 }
 
+func (self *ShortUUID) Random(num_bits int64) (string, error) {
+	max := big.NewInt(0).Exp(big.NewInt(2), big.NewInt(num_bits), nil)
+	bi, err := rand.Int(rand.Reader, max)
+	if err != nil {
+		return "", err
+	}
+	return num_to_string(bi, self.alphabet, &self.alphabet_len, self.pad_to_length), nil
+}
+
 func (self *ShortUUID) Uuid4() (string, error) {
 	b, err := uuid.NewRandom()
 	if err != nil {
@@ -92,3 +102,10 @@ func HumanUUID4() (string, error) {
 	}
 	return HumanUUID.Uuid4()
 }
+
+func HumanRandomId(num_bits int64) (string, error) {
+	if HumanUUID == nil {
+		HumanUUID = CreateShortUUID(HUMAN_ALPHABET)
+	}
+	return HumanUUID.Random(num_bits)
+}
diff --git a/tools/utils/short-uuid_test.go b/tools/utils/short-uuid_test.go
index 8f20dbda0..6a58763f2 100644
--- a/tools/utils/short-uuid_test.go
+++ b/tools/utils/short-uuid_test.go
@@ -8,11 +8,11 @@ import (
 )
 
 func TestShortUUID(t *testing.T) {
-	a, err := HumanUUID4()
+	a, err := HumanRandomId(128)
 	if err != nil {
 		t.Fatal(err)
 	}
-	b, err := HumanUUID4()
+	b, err := HumanRandomId(128)
 	if err != nil {
 		t.Fatal(err)
 	}