vendor: github.com/abbot/go-http-auth for #1802

vendor/github.com/abbot/go-http-auth/md5crypt.go

@@ -0,0 +1,92 @@
+package auth
+
+import "crypto/md5"
+import "strings"
+
+const itoa64 = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+
+var md5_crypt_swaps = [16]int{12, 6, 0, 13, 7, 1, 14, 8, 2, 15, 9, 3, 5, 10, 4, 11}
+
+type MD5Entry struct {
+	Magic, Salt, Hash []byte
+}
+
+func NewMD5Entry(e string) *MD5Entry {
+	parts := strings.SplitN(e, "$", 4)
+	if len(parts) != 4 {
+		return nil
+	}
+	return &MD5Entry{
+		Magic: []byte("$" + parts[1] + "$"),
+		Salt:  []byte(parts[2]),
+		Hash:  []byte(parts[3]),
+	}
+}
+
+/*
+ MD5 password crypt implementation
+*/
+func MD5Crypt(password, salt, magic []byte) []byte {
+	d := md5.New()
+
+	d.Write(password)
+	d.Write(magic)
+	d.Write(salt)
+
+	d2 := md5.New()
+	d2.Write(password)
+	d2.Write(salt)
+	d2.Write(password)
+
+	for i, mixin := 0, d2.Sum(nil); i < len(password); i++ {
+		d.Write([]byte{mixin[i%16]})
+	}
+
+	for i := len(password); i != 0; i >>= 1 {
+		if i&1 == 0 {
+			d.Write([]byte{password[0]})
+		} else {
+			d.Write([]byte{0})
+		}
+	}
+
+	final := d.Sum(nil)
+
+	for i := 0; i < 1000; i++ {
+		d2 := md5.New()
+		if i&1 == 0 {
+			d2.Write(final)
+		} else {
+			d2.Write(password)
+		}
+
+		if i%3 != 0 {
+			d2.Write(salt)
+		}
+
+		if i%7 != 0 {
+			d2.Write(password)
+		}
+
+		if i&1 == 0 {
+			d2.Write(password)
+		} else {
+			d2.Write(final)
+		}
+		final = d2.Sum(nil)
+	}
+
+	result := make([]byte, 0, 22)
+	v := uint(0)
+	bits := uint(0)
+	for _, i := range md5_crypt_swaps {
+		v |= (uint(final[i]) << bits)
+		for bits = bits + 8; bits > 6; bits -= 6 {
+			result = append(result, itoa64[v&0x3f])
+			v >>= 6
+		}
+	}
+	result = append(result, itoa64[v&0x3f])
+
+	return append(append(append(magic, salt...), '$'), result...)
+}