Rework SSLi_hash2hex() and SSLi_hex2hash().

This replaces the stdio-based implementation (printf(), scanf())
with a hand-written one. This should be worthwhile even if it's
unlikely that these functions show up in any profile.

diff --git a/src/ssl.h b/src/ssl.h
index ab02a2d6e407c4f54f1d9773162607f41fdbd34f..3c59f440b109611174571e07e6f178781bd92b8d 100644 (file)
--- a/src/ssl.h
+++ b/src/ssl.h
@@ -36,7 +36,6 @@
 #include "types.h"
 
 #include <inttypes.h>
-#include <stdio.h>
 #include <string.h>
 
 #if defined(USE_POLARSSL)
@@ -163,22 +162,40 @@ void SSLi_free(SSL_handle_t *ssl);
 
 static inline void SSLi_hash2hex(uint8_t *hash, char *out)
 {
+       const char hexdigits[] = "0123456789abcdef";
        int i, offset = 0;
-       for (i = 0; i < 20; i++)
-               offset += sprintf(out + offset, "%02x", hash[i]);
+       for (i = 0; i < 20; i++) {
+               out[offset++] = hexdigits[hash[i] >> 4];
+               out[offset++] = hexdigits[hash[i] & 0x0f];
+       }
+
+       out[offset] = '\0';
+}
+
+static inline uint8_t nibble(char c)
+{
+       if (c >= '0' && c <= '9')
+               return c - '0';
+
+       /* Force lower case so we don't need to check
+        * for upper case characters.
+        */
+       c |= 32;
+
+       return c - 'a' + 10;
 }
 
 static inline void SSLi_hex2hash(char *in, uint8_t *hash)
 {
-       int i;
-       char byte[3];
-       int scanned;
+       int i, offset = 0;
 
-       byte[2] = '\0';
        for (i = 0; i < 20; i++) {
-               memcpy(byte, &in[i * 2], 2);
-               sscanf(byte, "%02x", &scanned);
-               hash[i] = scanned;
+               uint8_t upper, lower;
+
+               upper = nibble(in[offset++]);
+               lower = nibble(in[offset++]);
+
+               hash[i] = (upper << 4) | lower;
        }
 }
 #endif