From: Stephan Bosch <stephan.bosch@dovecot.fi>
Date: Wed, 13 Feb 2019 18:00:11 +0000 (+0100)
Subject: lib: base64 - Make code suitable for encoding/decoding different Base64 variants.
X-Git-Tag: 2.3.8~138
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ca160577fce3d7cd70c8b02711dcad202e559846;p=thirdparty%2Fdovecot%2Fcore.git

lib: base64 - Make code suitable for encoding/decoding different Base64 variants.
---

diff --git a/src/lib/base64.c b/src/lib/base64.c
index a60a6af7ea..0b5f004c87 100644
--- a/src/lib/base64.c
+++ b/src/lib/base64.c
@@ -5,14 +5,14 @@
 #include "buffer.h"
 
 /*
- * "base64" encoding (RFC 4648, Section 4)
+ * Common Base 64
  */
 
-static const char b64enc[];
-static const unsigned char b64dec[256];
-
-void base64_encode(const void *src, size_t src_size, buffer_t *dest)
+void base64_scheme_encode(const struct base64_scheme *b64,
+			  const void *src, size_t src_size,
+			  buffer_t *dest)
 {
+	const char *b64enc = b64->encmap;
 	const size_t res_size = MAX_BASE64_ENCODED_SIZE(src_size);
 	unsigned char *start = buffer_append_space_unsafe(dest, res_size);
 	unsigned char *ptr = start;
@@ -54,9 +54,11 @@ void base64_encode(const void *src, size_t src_size, buffer_t *dest)
 #define IS_EMPTY(c) \
 	((c) == '\n' || (c) == '\r' || (c) == ' ' || (c) == '\t')
 
-int base64_decode(const void *src, size_t src_size,
-		  size_t *src_pos_r, buffer_t *dest)
+int base64_scheme_decode(const struct base64_scheme *b64,
+			 const void *src, size_t src_size, size_t *src_pos_r,
+			 buffer_t *dest)
 {
+	const unsigned char *b64dec = b64->decmap;
 	const unsigned char *src_c = src;
 	size_t src_pos;
 	unsigned char input[4], output[3];
@@ -122,64 +124,65 @@ int base64_decode(const void *src, size_t src_size,
 	return ret;
 }
 
-buffer_t *t_base64_decode_str(const char *str)
+buffer_t *t_base64_scheme_decode_str(const struct base64_scheme *b64,
+				     const char *str)
 {
 	buffer_t *buf;
 	size_t len = strlen(str);
 
 	buf = t_buffer_create(MAX_BASE64_DECODED_SIZE(len));
-	(void)base64_decode(str, len, NULL, buf);
+	(void)base64_scheme_decode(b64, str, len, NULL, buf);
 	return buf;
 }
 
-bool base64_is_valid_char(char c)
-{
-	return b64dec[(uint8_t)c] != 0xff;
-}
-
-static const char b64enc[64] = {
-       'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
-       'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
-       'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
-       'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
-       'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
-       'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
-       'w', 'x', 'y', 'z', '0', '1', '2', '3',
-       '4', '5', '6', '7', '8', '9', '+', '/',
-};
+/*
+ * "base64" encoding scheme (RFC 4648, Section 4)
+ */
 
-static const unsigned char b64dec[256] = {
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 0-7 */
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 8-15 */
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 16-23 */
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 24-31 */
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 32-39 */
-	0xff, 0xff, 0xff, 0x3e, 0xff, 0xff, 0xff, 0x3f, /* 40-47 */
-	0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, /* 48-55 */
-	0x3c, 0x3d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 56-63 */
-	0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, /* 64-71 */
-	0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, /* 72-79 */
-	0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, /* 80-87 */
-	0x17, 0x18, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff, /* 88-95 */
-	0xff, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, /* 96-103 */
-	0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, /* 104-111 */
-	0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, /* 112-119 */
-	0x31, 0x32, 0x33, 0xff, 0xff, 0xff, 0xff, 0xff, /* 120-127 */
-
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 128-255 */
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+struct base64_scheme base64_scheme = {
+	.encmap = {
+		'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
+		'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
+		'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
+		'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
+		'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
+		'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
+		'w', 'x', 'y', 'z', '0', '1', '2', '3',
+		'4', '5', '6', '7', '8', '9', '+', '/',
+	},
+	.decmap = {
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 0-7 */
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 8-15 */
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 16-23 */
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 24-31 */
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 32-39 */
+		0xff, 0xff, 0xff, 0x3e, 0xff, 0xff, 0xff, 0x3f, /* 40-47 */
+		0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, /* 48-55 */
+		0x3c, 0x3d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 56-63 */
+		0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, /* 64-71 */
+		0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, /* 72-79 */
+		0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, /* 80-87 */
+		0x17, 0x18, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff, /* 88-95 */
+		0xff, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, /* 96-103 */
+		0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, /* 104-111 */
+		0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, /* 112-119 */
+		0x31, 0x32, 0x33, 0xff, 0xff, 0xff, 0xff, 0xff, /* 120-127 */
+
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, /* 128-255 */
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+	},
 };
diff --git a/src/lib/base64.h b/src/lib/base64.h
index c52ec4fafe..664e652309 100644
--- a/src/lib/base64.h
+++ b/src/lib/base64.h
@@ -12,16 +12,31 @@
 #define MAX_BASE64_DECODED_SIZE(size) \
 	(((size) + 3) / 4 * 3)
 
+struct base64_scheme {
+	const char encmap[64];
+	const unsigned char decmap[256];
+};
+
 /*
- * "base64" encoding (RFC 4648, Section 4)
+ * Generic Base64 API
+ */
+
+/* Translates binary data into some variant of Base64. The src must not point to
+   dest buffer.
+
+   The b64 parameter is the definition of the particular Base 64 encoding scheme
+   that is used. See below for specific functions.
  */
+void base64_scheme_encode(const struct base64_scheme *b64,
+			  const void *src, size_t src_size,
+			  buffer_t *dest);
 
-/* Translates binary data into base64. The src must not point to dest buffer. */
-void base64_encode(const void *src, size_t src_size, buffer_t *dest);
+/* Translates some variant of Base64 data into binary and appends it to dest
+   buffer. dest may point to same buffer as src. Returns 1 if all ok, 0 if end
+   of Base64 data found, -1 if data is invalid.
 
-/* Translates base64 data into binary and appends it to dest buffer. dest may
-   point to same buffer as src. Returns 1 if all ok, 0 if end of base64 data
-   found, -1 if data is invalid.
+   The b64 parameter is the definition of the particular Base 64 encoding scheme
+   that is expected. See below for specific functions.
 
    Any CR, LF characters are ignored, as well as whitespace at beginning or
    end of line.
@@ -29,13 +44,59 @@ void base64_encode(const void *src, size_t src_size, buffer_t *dest);
    This function may be called multiple times for parsing the same stream.
    If src_pos is non-NULL, it's updated to first non-translated character in
    src. */
-int base64_decode(const void *src, size_t src_size,
-		  size_t *src_pos_r, buffer_t *dest) ATTR_NULL(3);
+int base64_scheme_decode(const struct base64_scheme *b64,
+			 const void *src, size_t src_size, size_t *src_pos_r,
+			 buffer_t *dest) ATTR_NULL(4);
+
+/* Decode given string to a buffer allocated from data stack.
+
+   The decmap is the mapping table used for the specific base64 encoding
+   variant. See below for specific functions.
+ */
+buffer_t *t_base64_scheme_decode_str(const struct base64_scheme *b64,
+				     const char *str);
+
+/* Returns TRUE if c is a valid encoding character (excluding '=') for the
+   provided base64 mapping table */
+static inline bool
+base64_scheme_is_valid_char(const struct base64_scheme *b64, char c)
+{
+	return b64->decmap[(uint8_t)c] != 0xff;
+}
+
+/*
+ * "base64" encoding scheme (RFC 4648, Section 4)
+ */
+
+extern struct base64_scheme base64_scheme;
+
+/* Translates binary data into base64. See base64_scheme_encode(). */
+static inline void
+base64_encode(const void *src, size_t src_size, buffer_t *dest)
+{
+	base64_scheme_encode(&base64_scheme, src, src_size, dest);
+}
+
+/* Translates base64 data into binary and appends it to dest buffer. See
+   base64_scheme_decode(). */
+static inline int
+base64_decode(const void *src, size_t src_size, size_t *src_pos_r,
+	      buffer_t *dest) ATTR_NULL(3)
+{
+	return base64_scheme_decode(&base64_scheme, src, src_size,
+				    src_pos_r, dest);
+}
 
 /* Decode given string to a buffer allocated from data stack. */
-buffer_t *t_base64_decode_str(const char *str);
+static inline buffer_t *t_base64_decode_str(const char *str)
+{
+	return t_base64_scheme_decode_str(&base64_scheme, str);
+}
 
 /* Returns TRUE if c is a valid base64 encoding character (excluding '=') */
-bool base64_is_valid_char(char c);
+static inline bool base64_is_valid_char(char c)
+{
+	return base64_scheme_is_valid_char(&base64_scheme, c);
+}
 
 #endif