update: do not hardcode sha1 hash length

src/misc/update.c

@@ -316,7 +316,7 @@ static bool GetUpdateFile( update_t *p_update )
             goto error;
         }
 
-        if( verify_signature( p_new_pkey->sig.r, p_new_pkey->sig.s,
+        if( verify_signature( &p_new_pkey->sig,
                     &p_update->p_pkey->key, p_hash ) == VLC_SUCCESS )
         {
             free( p_hash );
@@ -347,7 +347,7 @@ static bool GetUpdateFile( update_t *p_update )
         goto error;
     }
 
-    else if( verify_signature( sign.r, sign.s, &p_update->p_pkey->key, p_hash )
+    else if( verify_signature( &sign, &p_update->p_pkey->key, p_hash )
             != VLC_SUCCESS )
     {
         msg_Err( p_update->p_libvlc, "BAD SIGNATURE for status file" );
@@ -696,7 +696,7 @@ static void* update_DownloadReal( void *obj )
         goto end;
     }
 
-    if( verify_signature( sign.r, sign.s, &p_update->p_pkey->key, p_hash )
+    if( verify_signature( &sign, &p_update->p_pkey->key, p_hash )
             != VLC_SUCCESS )
     {
         vlc_unlink( psz_destfile );

src/misc/update.h

@@ -194,8 +194,7 @@ parse_public_key(
  * Verify an OpenPGP signature made on some SHA-1 hash, with some DSA public key
  */
 int
-verify_signature(
-        uint8_t *p_r, uint8_t *p_s, public_key_packet_t *p_key,
+verify_signature(signature_packet_t *sign, public_key_packet_t *p_key,
         uint8_t *p_hash );
 
 /*

src/misc/update_crypto.c

@@ -417,7 +417,7 @@ static int pgp_unarmor( const char *p_ibuf, size_t i_ibuf_len,
 /*
  * Verify an OpenPGP signature made on some SHA-1 hash, with some DSA public key
  */
-int verify_signature( uint8_t *p_r, uint8_t *p_s, public_key_packet_t *p_key,
+int verify_signature( signature_packet_t *sign, public_key_packet_t *p_key,
                       uint8_t *p_hash )
 {
     /* the data to be verified (a SHA-1 hash) */
@@ -444,6 +444,8 @@ int verify_signature( uint8_t *p_r, uint8_t *p_s, public_key_packet_t *p_key,
         gcry_sexp_build( &key_sexp, &erroff, key_sexp_s, p, q, g, y ) )
         goto problem;
 
+    uint8_t *p_r = sign->r;
+    uint8_t *p_s = sign->s;
     int i_r_len = mpi_len( p_r );
     int i_s_len = mpi_len( p_s );
     if( gcry_mpi_scan( &r, GCRYMPI_FMT_USG, p_r + 2, i_r_len, NULL ) ||
@@ -451,7 +453,7 @@ int verify_signature( uint8_t *p_r, uint8_t *p_s, public_key_packet_t *p_key,
         gcry_sexp_build( &sig_sexp, &erroff, sig_sexp_s, r, s ) )
         goto problem;
 
-    int i_hash_len = 20;
+    int i_hash_len = gcry_md_get_algo_dlen (sign->digest_algo);
     if( gcry_mpi_scan( &hash, GCRYMPI_FMT_USG, p_hash, i_hash_len, NULL ) ||
         gcry_sexp_build( &hash_sexp, &erroff, hash_sexp_s, hash ) )
         goto problem;
@@ -655,9 +657,10 @@ static uint8_t *hash_finish( gcry_md_hd_t hd, signature_packet_t *p_sig )
     gcry_md_final( hd );
 
     uint8_t *p_tmp = (uint8_t*) gcry_md_read( hd, p_sig->digest_algo) ;
-    uint8_t *p_hash = malloc( 20 );
+    unsigned int hash_len = gcry_md_get_algo_dlen (p_sig->digest_algo);
+    uint8_t *p_hash = malloc(hash_len);
     if( p_hash )
-        memcpy( p_hash, p_tmp, 20 );
+        memcpy(p_hash, p_tmp, hash_len);
     gcry_md_close( hd );
     return p_hash;
 }