New utility function to reverse a buffer, either by copying or in-place.

crypto/buffer/buffer.c

@@ -219,3 +219,26 @@ size_t BUF_strlcat(char *dst, const char *src, size_t size)
 		l++;
 	return l + BUF_strlcpy(dst, src, size);
 	}
+
+void BUF_reverse(unsigned char *out, unsigned char *in, size_t size)
+	{
+	size_t i;
+	if (in)
+		{
+		out += size - 1;
+		for (i = 0; i < size; i++)
+			*in++ = *out--;
+		}
+	else
+		{
+		unsigned char *q;
+		char c;
+		q = out + size - 1;
+		for (i = 0; i < size/2; i++)
+			{
+			c = *q;
+			*q-- = *out;
+			*out++ = c;
+			}
+		}
+	}

crypto/buffer/buffer.h

@@ -88,6 +88,7 @@ int	BUF_MEM_grow_clean(BUF_MEM *str, int len);
 char *	BUF_strdup(const char *str);
 char *	BUF_strndup(const char *str, size_t siz);
 void *	BUF_memdup(const void *data, size_t siz);
+void	BUF_reverse(unsigned char *out, unsigned char *in, size_t siz);
 
 /* safe string functions */
 size_t BUF_strlcpy(char *dst,const char *src,size_t siz);