Introduced gnutls_hex_encode2() and gnutls_hex_decode2()

These also use safer hex decoding functions which don't skip
invalid input.

4 files changed, 175 insertions, 1 deletions

diff --git a/lib/extras/Makefile.am b/lib/extras/Makefile.am
index b621de9b94..8f9b63be50 100644
--- a/lib/extras/Makefile.am
+++ b/lib/extras/Makefile.am
@@ -28,10 +28,12 @@ AM_CPPFLAGS = \
 	-I$(srcdir)/..			\
 	-I$(srcdir)/../opencdk
 
+EXTRA_DIST = licenses/CC0
+
 if ENABLE_MINITASN1
 AM_CPPFLAGS += -I$(srcdir)/../minitasn1
 endif
 
 noinst_LTLIBRARIES = libgnutls_extras.la
 
-libgnutls_extras_la_SOURCES = randomart.c randomart.h
+libgnutls_extras_la_SOURCES = randomart.c randomart.h hex.c hex.h
diff --git a/lib/extras/hex.c b/lib/extras/hex.c
new file mode 100644
index 0000000000..55ce6073e8
--- /dev/null
+++ b/lib/extras/hex.c
@@ -0,0 +1,71 @@
+/* CC0 license (public domain) - see LICENSE file for details */
+#include <config.h>
+#include <hex.h>
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static bool char_to_hex(unsigned char *val, char c)
+{
+	if (c >= '0' && c <= '9') {
+		*val = c - '0';
+		return true;
+	}
+ 	if (c >= 'a' && c <= 'f') {
+		*val = c - 'a' + 10;
+		return true;
+	}
+ 	if (c >= 'A' && c <= 'F') {
+		*val = c - 'A' + 10;
+		return true;
+	}
+	return false;
+}
+
+bool hex_decode(const char *str, size_t slen, void *buf, size_t bufsize)
+{
+	unsigned char v1, v2;
+	unsigned char *p = buf;
+
+	while (slen > 1) {
+		if (!char_to_hex(&v1, str[0]) || !char_to_hex(&v2, str[1]))
+			return false;
+		if (!bufsize)
+			return false;
+		*(p++) = (v1 << 4) | v2;
+		str += 2;
+		slen -= 2;
+		bufsize--;
+	}
+	return slen == 0 && bufsize == 0;
+}
+
+static char hexchar(unsigned int val)
+{
+	if (val < 10)
+		return '0' + val;
+	if (val < 16)
+		return 'a' + val - 10;
+	abort();
+}
+
+bool hex_encode(const void *buf, size_t bufsize, char *dest, size_t destsize)
+{
+	size_t used = 0;
+
+	if (destsize < 1)
+		return false;
+
+	while (used < bufsize) {
+		unsigned int c = ((const unsigned char *)buf)[used];
+		if (destsize < 3)
+			return false;
+		*(dest++) = hexchar(c >> 4);
+		*(dest++) = hexchar(c & 0xF);
+		used++;
+		destsize -= 2;
+	}
+	*dest = '\0';
+
+	return used + 1;
+}
diff --git a/lib/extras/hex.h b/lib/extras/hex.h
new file mode 100644
index 0000000000..0a0d5c5aa8
--- /dev/null
+++ b/lib/extras/hex.h
@@ -0,0 +1,73 @@
+/* CC0 (Public domain) - see LICENSE file for details */
+#ifndef CCAN_HEX_H
+#define CCAN_HEX_H
+#include "config.h"
+#include <stdbool.h>
+#include <stdlib.h>
+
+/**
+ * hex_decode - Unpack a hex string.
+ * @str: the hexidecimal string
+ * @slen: the length of @str
+ * @buf: the buffer to write the data into
+ * @bufsize: the length of @buf
+ *
+ * Returns false if there are any characters which aren't 0-9, a-f or A-F,
+ * of the string wasn't the right length for @bufsize.
+ *
+ * Example:
+ *	unsigned char data[20];
+ *
+ *	if (!hex_decode(argv[1], strlen(argv[1]), data, 20))
+ *		printf("String is malformed!\n");
+ */
+bool hex_decode(const char *str, size_t slen, void *buf, size_t bufsize);
+
+/**
+ * hex_encode - Create a nul-terminated hex string
+ * @buf: the buffer to read the data from
+ * @bufsize: the length of @buf
+ * @dest: the string to fill
+ * @destsize: the max size of the string
+ *
+ * Returns true if the string, including terminator, fit in @destsize;
+ *
+ * Example:
+ *	unsigned char buf[] = { 0x1F, 0x2F };
+ *	char str[5];
+ *
+ *	if (!hex_encode(buf, sizeof(buf), str, sizeof(str)))
+ *		abort();
+ */
+bool hex_encode(const void *buf, size_t bufsize, char *dest, size_t destsize);
+
+/**
+ * hex_str_size - Calculate how big a nul-terminated hex string is
+ * @bytes: bytes of data to represent
+ *
+ * Example:
+ *	unsigned char buf[] = { 0x1F, 0x2F };
+ *	char str[hex_str_size(sizeof(buf))];
+ *
+ *	hex_encode(buf, sizeof(buf), str, sizeof(str));
+ */
+static inline size_t hex_str_size(size_t bytes)
+{
+	return 2 * bytes + 1;
+}
+
+/**
+ * hex_data_size - Calculate how many bytes of data in a hex string
+ * @strlen: the length of the string (with or without NUL)
+ *
+ * Example:
+ *	const char str[] = "1F2F";
+ *	unsigned char buf[hex_data_size(sizeof(str))];
+ *
+ *	hex_decode(str, strlen(str), buf, sizeof(buf));
+ */
+static inline size_t hex_data_size(size_t strlen)
+{
+	return strlen / 2;
+}
+#endif /* PETTYCOIN_HEX_H */
diff --git a/lib/extras/licenses/CC0 b/lib/extras/licenses/CC0
new file mode 100644
index 0000000000..feb9b118e6
--- /dev/null
+++ b/lib/extras/licenses/CC0
@@ -0,0 +1,28 @@
+Statement of Purpose
+
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