Use inline functions to convert buffer data to scalars.

* common/host2net.h (buf16_to_ulong, buf16_to_uint): New.
(buf16_to_ushort, buf16_to_u16): New.
(buf32_to_size_t, buf32_to_ulong, buf32_to_uint, buf32_to_u32): New.
--

Commit 91b826a388 was not enough to
avoid all sign extension on shift problems.  Hanno Böck found a case
with an invalid read due to this problem.  To fix that once and for
all almost all uses of "<< 24" and "<< 8" are changed by this patch to
use an inline function from host2net.h.

Signed-off-by: Werner Koch <wk@gnupg.org>

sm/fingerprint.c

@@ -31,6 +31,9 @@
 #include <gcrypt.h>
 #include <ksba.h>
 
+#include "host2net.h"
+
+
 /* Return the fingerprint of the certificate (we can't put this into
    libksba because we need libgcrypt support).  The caller must
    provide an array of sufficient length or NULL so that the function
@@ -149,14 +152,8 @@ gpgsm_get_short_fingerprint (ksba_cert_t cert, unsigned long *r_high)
 
   gpgsm_get_fingerprint (cert, GCRY_MD_SHA1, digest, NULL);
   if (r_high)
-    *r_high = (((unsigned long)digest[12]<<24)
-               |(digest[13]<<16)
-               |(digest[14]<< 8)
-               |digest[15]);
-  return (((unsigned long)digest[16]<<24)
-          |(digest[17]<<16)
-          |(digest[18]<<8)
-          |digest[19]);
+    *r_high = buf32_to_ulong (digest+12);
+  return buf32_to_ulong (digest + 16);
 }