str/hex: to-from hexstring conversion routines.

[ccan] / ccan / str / hex / hex.c

diff --git a/ccan/str/hex/hex.c b/ccan/str/hex/hex.c
new file mode 100644 (file)
index 0000000..fd4074f
--- /dev/null
+++ b/ccan/str/hex/hex.c
@@ -0,0 +1,70 @@
+/* CC0 license (public domain) - see LICENSE file for details */
+#include <ccan/str/hex/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;
+}