This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3, or (at your option)
+ the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
/* Get UCHAR_MAX. */
#include <limits.h>
+#include <string.h>
+
/* C89 compliant way to cast 'char' to 'unsigned char'. */
static inline unsigned char
to_uchar (char ch)
possible. If OUTLEN is larger than BASE64_LENGTH(INLEN), also zero
terminate the output buffer. */
void
-base64_encode (const char *in, size_t inlen,
- char *out, size_t outlen)
+base64_encode (const char *restrict in, size_t inlen,
+ char *restrict out, size_t outlen)
{
static const char b64str[64] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
return uchar_in_range (to_uchar (ch)) && 0 <= b64[to_uchar (ch)];
}
-/* Decode base64 encoded input array IN of length INLEN to output
- array OUT that can hold *OUTLEN bytes. Return true if decoding was
- successful, i.e. if the input was valid base64 data, false
- otherwise. If *OUTLEN is too small, as many bytes as possible will
- be written to OUT. On return, *OUTLEN holds the length of decoded
- bytes in OUT. Note that as soon as any non-alphabet characters are
- encountered, decoding is stopped and false is returned. This means
- that, when applicable, you must remove any line terminators that is
- part of the data stream before calling this function. */
-bool
-base64_decode (const char *in, size_t inlen,
- char *out, size_t *outlen)
+/* Initialize decode-context buffer, CTX. */
+void
+base64_decode_ctx_init (struct base64_decode_context *ctx)
{
- size_t outleft = *outlen;
+ ctx->i = 0;
+}
- while (inlen >= 2)
- {
- if (!isbase64 (in[0]) || !isbase64 (in[1]))
- break;
+/* If CTX->i is 0 or 4, there are four or more bytes in [*IN..IN_END), and
+ none of those four is a newline, then return *IN. Otherwise, copy up to
+ 4 - CTX->i non-newline bytes from that range into CTX->buf, starting at
+ index CTX->i and setting CTX->i to reflect the number of bytes copied,
+ and return CTX->buf. In either case, advance *IN to point to the byte
+ after the last one processed, and set *N_NON_NEWLINE to the number of
+ verified non-newline bytes accessible through the returned pointer. */
+static inline char *
+get_4 (struct base64_decode_context *ctx,
+ char const *restrict *in, char const *restrict in_end,
+ size_t *n_non_newline)
+{
+ if (ctx->i == 4)
+ ctx->i = 0;
- if (outleft)
+ if (ctx->i == 0)
+ {
+ char const *t = *in;
+ if (4 <= in_end - *in && memchr (t, '\n', 4) == NULL)
{
- *out++ = ((b64[to_uchar (in[0])] << 2)
- | (b64[to_uchar (in[1])] >> 4));
- outleft--;
+ /* This is the common case: no newline. */
+ *in += 4;
+ *n_non_newline = 4;
+ return (char *) t;
}
+ }
- if (inlen == 2)
- break;
+ {
+ /* Copy non-newline bytes into BUF. */
+ char const *p = *in;
+ while (p < in_end)
+ {
+ char c = *p++;
+ if (c != '\n')
+ {
+ ctx->buf[ctx->i++] = c;
+ if (ctx->i == 4)
+ break;
+ }
+ }
+
+ *in = p;
+ *n_non_newline = ctx->i;
+ return ctx->buf;
+ }
+}
+
+#define return_false \
+ do \
+ { \
+ *outp = out; \
+ return false; \
+ } \
+ while (false)
+
+/* Decode up to four bytes of base64-encoded data, IN, of length INLEN
+ into the output buffer, *OUT, of size *OUTLEN bytes. Return true if
+ decoding is successful, false otherwise. If *OUTLEN is too small,
+ as many bytes as possible are written to *OUT. On return, advance
+ *OUT to point to the byte after the last one written, and decrement
+ *OUTLEN to reflect the number of bytes remaining in *OUT. */
+static inline bool
+decode_4 (char const *restrict in, size_t inlen,
+ char *restrict *outp, size_t *outleft)
+{
+ char *out = *outp;
+ if (inlen < 2)
+ return false;
+
+ if (!isbase64 (in[0]) || !isbase64 (in[1]))
+ return false;
+
+ if (*outleft)
+ {
+ *out++ = ((b64[to_uchar (in[0])] << 2)
+ | (b64[to_uchar (in[1])] >> 4));
+ --*outleft;
+ }
+
+ if (inlen == 2)
+ return_false;
+
+ if (in[2] == '=')
+ {
+ if (inlen != 4)
+ return_false;
+
+ if (in[3] != '=')
+ return_false;
+ }
+ else
+ {
+ if (!isbase64 (in[2]))
+ return_false;
- if (in[2] == '=')
+ if (*outleft)
{
- if (inlen != 4)
- break;
+ *out++ = (((b64[to_uchar (in[1])] << 4) & 0xf0)
+ | (b64[to_uchar (in[2])] >> 2));
+ --*outleft;
+ }
- if (in[3] != '=')
- break;
+ if (inlen == 3)
+ return_false;
+ if (in[3] == '=')
+ {
+ if (inlen != 4)
+ return_false;
}
else
{
- if (!isbase64 (in[2]))
- break;
+ if (!isbase64 (in[3]))
+ return_false;
- if (outleft)
+ if (*outleft)
{
- *out++ = (((b64[to_uchar (in[1])] << 4) & 0xf0)
- | (b64[to_uchar (in[2])] >> 2));
- outleft--;
+ *out++ = (((b64[to_uchar (in[2])] << 6) & 0xc0)
+ | b64[to_uchar (in[3])]);
+ --*outleft;
}
+ }
+ }
- if (inlen == 3)
- break;
+ *outp = out;
+ return true;
+}
- if (in[3] == '=')
- {
- if (inlen != 4)
- break;
- }
- else
+/* Decode base64-encoded input array IN of length INLEN to output array
+ OUT that can hold *OUTLEN bytes. The input data may be interspersed
+ with newlines. Return true if decoding was successful, i.e. if the
+ input was valid base64 data, false otherwise. If *OUTLEN is too
+ small, as many bytes as possible will be written to OUT. On return,
+ *OUTLEN holds the length of decoded bytes in OUT. Note that as soon
+ as any non-alphabet, non-newline character is encountered, decoding
+ is stopped and false is returned. If INLEN is zero, then process
+ only whatever data is stored in CTX.
+
+ Initially, CTX must have been initialized via base64_decode_ctx_init.
+ Subsequent calls to this function must reuse whatever state is recorded
+ in that buffer. It is necessary for when a quadruple of base64 input
+ bytes spans two input buffers.
+
+ If CTX is NULL then newlines are treated as garbage and the input
+ buffer is processed as a unit. */
+
+bool
+base64_decode_ctx (struct base64_decode_context *ctx,
+ const char *restrict in, size_t inlen,
+ char *restrict out, size_t *outlen)
+{
+ size_t outleft = *outlen;
+ bool ignore_newlines = ctx != NULL;
+ bool flush_ctx = false;
+ unsigned int ctx_i = 0;
+
+ if (ignore_newlines)
+ {
+ ctx_i = ctx->i;
+ flush_ctx = inlen == 0;
+ }
+
+
+ while (true)
+ {
+ size_t outleft_save = outleft;
+ if (ctx_i == 0 && !flush_ctx)
+ {
+ while (true)
{
- if (!isbase64 (in[3]))
+ /* Save a copy of outleft, in case we need to re-parse this
+ block of four bytes. */
+ outleft_save = outleft;
+ if (!decode_4 (in, inlen, &out, &outleft))
break;
- if (outleft)
- {
- *out++ = (((b64[to_uchar (in[2])] << 6) & 0xc0)
- | b64[to_uchar (in[3])]);
- outleft--;
- }
+ in += 4;
+ inlen -= 4;
}
}
- in += 4;
- inlen -= 4;
+ if (inlen == 0 && !flush_ctx)
+ break;
+
+ /* Handle the common case of 72-byte wrapped lines.
+ This also handles any other multiple-of-4-byte wrapping. */
+ if (inlen && *in == '\n' && ignore_newlines)
+ {
+ ++in;
+ --inlen;
+ continue;
+ }
+
+ /* Restore OUT and OUTLEFT. */
+ out -= outleft_save - outleft;
+ outleft = outleft_save;
+
+ {
+ char const *in_end = in + inlen;
+ char const *non_nl;
+
+ if (ignore_newlines)
+ non_nl = get_4 (ctx, &in, in_end, &inlen);
+ else
+ non_nl = in; /* Might have nl in this case. */
+
+ /* If the input is empty or consists solely of newlines (0 non-newlines),
+ then we're done. Likewise if there are fewer than 4 bytes when not
+ flushing context and not treating newlines as garbage. */
+ if (inlen == 0 || (inlen < 4 && !flush_ctx && ignore_newlines))
+ {
+ inlen = 0;
+ break;
+ }
+ if (!decode_4 (non_nl, inlen, &out, &outleft))
+ break;
+
+ inlen = in_end - in;
+ }
}
*outlen -= outleft;
- if (inlen != 0)
- return false;
-
- return true;
+ return inlen == 0;
}
/* Allocate an output buffer in *OUT, and decode the base64 encoded
input was invalid, in which case *OUT is NULL and *OUTLEN is
undefined. */
bool
-base64_decode_alloc (const char *in, size_t inlen, char **out,
- size_t *outlen)
+base64_decode_alloc_ctx (struct base64_decode_context *ctx,
+ const char *in, size_t inlen, char **out,
+ size_t *outlen)
{
- /* This may allocate a few bytes too much, depending on input,
- but it's not worth the extra CPU time to compute the exact amount.
- The exact amount is 3 * inlen / 4, minus 1 if the input ends
+ /* This may allocate a few bytes too many, depending on input,
+ but it's not worth the extra CPU time to compute the exact size.
+ The exact size is 3 * inlen / 4, minus 1 if the input ends
with "=" and minus another 1 if the input ends with "==".
Dividing before multiplying avoids the possibility of overflow. */
size_t needlen = 3 * (inlen / 4) + 2;
if (!*out)
return true;
- if (!base64_decode (in, inlen, *out, &needlen))
+ if (!base64_decode_ctx (ctx, in, inlen, *out, &needlen))
{
free (*out);
*out = NULL;
projects / debian / amanda / blobdiff