[MINOR] add encode/decode function for 30-bit integers from/to base64
These functions only require 5 chars to encode 30 bits, and don't expect
any padding. They will be used to encode dates in cookies.
(cherry picked from commit a7e2b5fc4612994c7b13bcb103a4a2c3ecd6438a)
diff --git a/src/base64.c b/src/base64.c
index ea244a2..594ab45 100644
--- a/src/base64.c
+++ b/src/base64.c
@@ -1,7 +1,7 @@
/*
* ASCII <-> Base64 conversion as described in RFC1421.
*
- * Copyright 2006-2008 Willy Tarreau <w@1wt.eu>
+ * Copyright 2006-2010 Willy Tarreau <w@1wt.eu>
* Copyright 2009-2010 Krzysztof Piotr Oledzki <ole@ans.pl>
*
* This program is free software; you can redistribute it and/or
@@ -135,3 +135,50 @@
return convlen;
}
+
+
+/* Converts the lower 30 bits of an integer to a 5-char base64 string. The
+ * caller is responsible for ensuring that the output buffer can accept 6 bytes
+ * (5 + the trailing zero). The pointer to the string is returned. The
+ * conversion is performed with MSB first and in a format that can be
+ * decoded with b64tos30(). This format is not padded and thus is not
+ * compatible with usual base64 routines.
+ */
+const char *s30tob64(int in, char *out)
+{
+ int i;
+ for (i = 0; i < 5; i++) {
+ out[i] = base64tab[(in >> 24) & 0x3F];
+ in <<= 6;
+ }
+ out[5] = '\0';
+ return out;
+}
+
+/* Converts a 5-char base64 string encoded by s30tob64() into a 30-bit integer.
+ * The caller is responsible for ensuring that the input contains at least 5
+ * chars. If any unexpected character is encountered, a negative value is
+ * returned. Otherwise the decoded value is returned.
+ */
+int b64tos30(const char *in)
+{
+ int i, out;
+ signed char b;
+
+ out = 0;
+ for (i = 0; i < 5; i++) {
+ b = (signed char)in[i] - B64CMIN;
+ if ((unsigned char)b > (B64CMAX - B64CMIN))
+ return -1; /* input character out of range */
+
+ b = base64rev[b] - B64BASE - 1;
+ if (b < 0) /* invalid character */
+ return -1;
+
+ if (b == B64PADV) /* padding not allowed */
+ return -1;
+
+ out = (out << 6) + b;
+ }
+ return out;
+}