X-Git-Url: https://bearssl.org/gitweb//home/git/?p=BearSSL;a=blobdiff_plain;f=src%2Fcodec%2Fpemenc.c;fp=src%2Fcodec%2Fpemenc.c;h=236601e60d45a24e078df4468993a94c6f829141;hp=0000000000000000000000000000000000000000;hb=d8fa415fcabecb7d7c8461d8edbe2f265911e72c;hpb=cfbc702d3d64c209784b664eeab8867b603f4d4c

diff --git a/src/codec/pemenc.c b/src/codec/pemenc.c
new file mode 100644
index 0000000..236601e
--- /dev/null
+++ b/src/codec/pemenc.c
@@ -0,0 +1,173 @@
+/*
+ * Copyright (c) 2018 Thomas Pornin <pornin@bolet.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining 
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be 
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "inner.h"
+
+/*
+ * Get the appropriate Base64 character for a numeric value in the
+ * 0..63 range. This is constant-time.
+ */
+static char
+b64char(uint32_t x)
+{
+	/*
+	 * Values 0 to 25 map to 0x41..0x5A ('A' to 'Z')
+	 * Values 26 to 51 map to 0x61..0x7A ('a' to 'z')
+	 * Values 52 to 61 map to 0x30..0x39 ('0' to '9')
+	 * Value 62 maps to 0x2B ('+')
+	 * Value 63 maps to 0x2F ('/')
+	 */
+	uint32_t a, b, c;
+
+	a = x - 26;
+	b = x - 52;
+	c = x - 62;
+
+	/*
+	 * Looking at bits 8..15 of values a, b and c:
+	 *
+	 *     x       a   b   c
+	 *  ---------------------
+	 *   0..25    FF  FF  FF
+	 *   26..51   00  FF  FF
+	 *   52..61   00  00  FF
+	 *   62..63   00  00  00
+	 */
+	return (char)(((x + 0x41) & ((a & b & c) >> 8))
+		| ((x + (0x61 - 26)) & ((~a & b & c) >> 8))
+		| ((x - (52 - 0x30)) & ((~a & ~b & c) >> 8))
+		| ((0x2B + ((x & 1) << 2)) & (~(a | b | c) >> 8)));
+}
+
+/* see bearssl_pem.h */
+size_t
+br_pem_encode(void *dest, const void *data, size_t len,
+	const char *banner, unsigned flags)
+{
+	size_t dlen, banner_len, lines;
+	char *d;
+	unsigned char *buf;
+	size_t u;
+	int off, lim;
+
+	banner_len = strlen(banner);
+	/* FIXME: try to avoid divisions here, as they may pull
+	   an extra libc function. */
+	if ((flags & BR_PEM_LINE64) != 0) {
+		lines = (len + 47) / 48;
+	} else {
+		lines = (len + 56) / 57;
+	}
+	dlen = (banner_len << 1) + 30 + (((len + 2) / 3) << 2)
+		+ lines + 2;
+	if ((flags & BR_PEM_CRLF) != 0) {
+		dlen += lines + 2;
+	}
+
+	if (dest == NULL) {
+		return dlen;
+	}
+
+	d = dest;
+
+	/*
+	 * We always move the source data to the end of output buffer;
+	 * the encoding process never "catches up" except at the very
+	 * end. This also handles all conditions of partial or total
+	 * overlap.
+	 */
+	buf = (unsigned char *)d + dlen - len;
+	memmove(buf, data, len);
+
+	memcpy(d, "-----BEGIN ", 11);
+	d += 11;
+	memcpy(d, banner, banner_len);
+	d += banner_len;
+	memcpy(d, "-----", 5);
+	d += 5;
+	if ((flags & BR_PEM_CRLF) != 0) {
+		*d ++ = 0x0D;
+	}
+	*d ++ = 0x0A;
+
+	off = 0;
+	lim = (flags & BR_PEM_LINE64) != 0 ? 16 : 19;
+	for (u = 0; (u + 2) < len; u += 3) {
+		uint32_t w;
+
+		w = ((uint32_t)buf[u] << 16)
+			| ((uint32_t)buf[u + 1] << 8)
+			| (uint32_t)buf[u + 2];
+		*d ++ = b64char(w >> 18);
+		*d ++ = b64char((w >> 12) & 0x3F);
+		*d ++ = b64char((w >> 6) & 0x3F);
+		*d ++ = b64char(w & 0x3F);
+		if (++ off == lim) {
+			off = 0;
+			if ((flags & BR_PEM_CRLF) != 0) {
+				*d ++ = 0x0D;
+			}
+			*d ++ = 0x0A;
+		}
+	}
+	if (u < len) {
+		uint32_t w;
+
+		w = (uint32_t)buf[u] << 16;
+		if (u + 1 < len) {
+			w |= (uint32_t)buf[u + 1] << 8;
+		}
+		*d ++ = b64char(w >> 18);
+		*d ++ = b64char((w >> 12) & 0x3F);
+		if (u + 1 < len) {
+			*d ++ = b64char((w >> 6) & 0x3F);
+		} else {
+			*d ++ = 0x3D;
+		}
+		*d ++ = 0x3D;
+		off ++;
+	}
+	if (off != 0) {
+		if ((flags & BR_PEM_CRLF) != 0) {
+			*d ++ = 0x0D;
+		}
+		*d ++ = 0x0A;
+	}
+
+	memcpy(d, "-----END ", 9);
+	d += 9;
+	memcpy(d, banner, banner_len);
+	d += banner_len;
+	memcpy(d, "-----", 5);
+	d += 5;
+	if ((flags & BR_PEM_CRLF) != 0) {
+		*d ++ = 0x0D;
+	}
+	*d ++ = 0x0A;
+
+	/* Final zero, not counted in returned length. */
+	*d ++ = 0x00;
+
+	return dlen;
+}