Define the SHA-1 digest length in wsutil/sha1.h and use it.

Hopefully that'll make it a little easier to make sure that we're not
overflowing arrays.

Change-Id: I770df045ef9a45fd486c1271ea424b3334bb39d2
Reviewed-on: https://code.wireshark.org/review/8370
Reviewed-by: Guy Harris <guy@alum.mit.edu>

2 files changed, 16 insertions, 11 deletions

diff --git a/wsutil/sha1.c b/wsutil/sha1.c
index b7a2a76cef..3aaf557052 100644
--- a/wsutil/sha1.c
+++ b/wsutil/sha1.c
@@ -261,7 +261,7 @@ static guint8 sha1_padding[64] =
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 };
 
-void sha1_finish( sha1_context *ctx, guint8 digest[20] )
+void sha1_finish( sha1_context *ctx, guint8 digest[SHA1_DIGEST_LEN] )
 {
     guint32 last, padn;
     guint32 high, low;
@@ -312,20 +312,20 @@ void sha1_hmac_update( sha1_hmac_context *hctx, const guint8 *buf, guint32 bufle
     sha1_update( &hctx->ctx, buf, buflen );
 }
 
-void sha1_hmac_finish( sha1_hmac_context *hctx, guint8 digest[20] )
+void sha1_hmac_finish( sha1_hmac_context *hctx, guint8 digest[SHA1_DIGEST_LEN] )
 {
-    guint8 tmpbuf[20];
+    guint8 tmpbuf[SHA1_DIGEST_LEN];
 
     sha1_finish( &hctx->ctx, tmpbuf );
 
     sha1_starts( &hctx->ctx );
     sha1_update( &hctx->ctx, hctx->k_opad, 64 );
-    sha1_update( &hctx->ctx, tmpbuf, 20 );
+    sha1_update( &hctx->ctx, tmpbuf, SHA1_DIGEST_LEN );
     sha1_finish( &hctx->ctx, digest );
 }
 
 void sha1_hmac( const guint8 *key, guint32 keylen, const guint8 *buf, guint32 buflen,
-                guint8 digest[20] )
+                guint8 digest[SHA1_DIGEST_LEN] )
 {
     sha1_hmac_context hctx;
 
@@ -365,7 +365,7 @@ int main( int argc, char *argv[] )
     char output[41];
     sha1_context ctx;
     unsigned char buf[1000];
-    unsigned char sha1sum[20];
+    unsigned char sha1sum[SHA1_DIGEST_LEN];
 
     if( argc < 2 )
     {
@@ -394,7 +394,7 @@ int main( int argc, char *argv[] )
 
             sha1_finish( &ctx, sha1sum );
 
-            for( j = 0; j < 20; j++ )
+            for( j = 0; j < SHA1_DIGEST_LEN; j++ )
             {
                 g_snprintf( output + j * 2, 41-j*2, "%02x", sha1sum[j] );
             }
@@ -427,7 +427,7 @@ int main( int argc, char *argv[] )
 
         sha1_finish( &ctx, sha1sum );
 
-        for( j = 0; j < 20; j++ )
+        for( j = 0; j < SHA1_DIGEST_LEN; j++ )
         {
             printf( "%02x", sha1sum[j] );
         }
diff --git a/wsutil/sha1.h b/wsutil/sha1.h
index f4f9d86a1c..52a9842d57 100644
--- a/wsutil/sha1.h
+++ b/wsutil/sha1.h
@@ -30,6 +30,11 @@
 
 #include "ws_symbol_export.h"
 
+/*
+ * Length of a SHA-1 digest, in bytes.  160 bits = 20 bytes.
+ */
+#define SHA1_DIGEST_LEN 20
+
 typedef struct
 {
     guint32 total[2];
@@ -43,7 +48,7 @@ void sha1_starts( sha1_context *ctx );
 WS_DLL_PUBLIC
 void sha1_update( sha1_context *ctx, const guint8 *input, guint32 length );
 WS_DLL_PUBLIC
-void sha1_finish( sha1_context *ctx, guint8 digest[20] );
+void sha1_finish( sha1_context *ctx, guint8 digest[SHA1_DIGEST_LEN] );
 
 typedef struct {
     sha1_context ctx;
@@ -56,9 +61,9 @@ void sha1_hmac_starts( sha1_hmac_context *hctx, const guint8 *key, guint32 keyle
 WS_DLL_PUBLIC
 void sha1_hmac_update( sha1_hmac_context *hctx, const guint8 *buf, guint32 buflen );
 WS_DLL_PUBLIC
-void sha1_hmac_finish( sha1_hmac_context *hctx, guint8 digest[20] );
+void sha1_hmac_finish( sha1_hmac_context *hctx, guint8 digest[SHA1_DIGEST_LEN] );
 WS_DLL_PUBLIC
 void sha1_hmac( const guint8 *key, guint32 keylen, const guint8 *buf, guint32 buflen,
-                guint8 digest[20] );
+                guint8 digest[SHA1_DIGEST_LEN] );
 
 #endif /* sha1.h */