snapshot of https://github.com/cortezaproject/corteza.git (2024.9.x, 2026-09-18; blobs > 131072B omitted)

server/pkg/rand/rand.go

@@ -0,0 +1,67 @@
+package rand
+
+import (
+	"math/rand"
+	"sync"
+	"time"
+)
+
+// credits: https://stackoverflow.com/questions/22892120/how-to-generate-a-random-string-of-a-fixed-length-in-golang
+
+const (
+	letterSpecials = "~=+%^*/()[]{}/!@#$?|"
+	letterDigits   = "0123456789"
+	letterBytes    = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" + letterDigits
+	letterIdxBits  = 6                    // 6 bits to represent a letter index
+	letterIdxMask  = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
+	letterIdxMax   = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
+)
+
+var randSrc = rand.NewSource(time.Now().UnixNano())
+var mu sync.Mutex
+
+func Bytes(n int) []byte {
+	mu.Lock()
+	defer mu.Unlock()
+
+	b := make([]byte, n)
+
+	// A randSrc.Int63() generates 63 random bits, enough for letterIdxMax characters!
+	for i, cache, remain := n-1, randSrc.Int63(), letterIdxMax; i >= 0; {
+		if remain == 0 {
+			cache, remain = randSrc.Int63(), letterIdxMax
+		}
+		if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
+			b[i] = letterBytes[idx]
+			i--
+		}
+		cache >>= letterIdxBits
+		remain--
+	}
+
+	return b
+}
+
+// Password generates a random ASCII string with at least one digit and one special character
+func Password(n int) string {
+	mu.Lock()
+	defer mu.Unlock()
+
+	b := make([]byte, n)
+
+	for i := 0; i < n; i++ {
+		var s string
+		if i == 0 {
+			s = letterDigits
+		} else if i == 1 {
+			s = letterSpecials
+		} else {
+			s = letterBytes
+		}
+		b[i] = s[rand.Intn(len(s))]
+	}
+	rand.Shuffle(len(b), func(i, j int) {
+		b[i], b[j] = b[j], b[i]
+	})
+	return string(b) // E.g. "3i[g0|)z"
+}