Const correctness and const-ref in Crypto and elsewhere.

src/crypto/crypto.cc

@@ -184,14 +184,14 @@ Nonce::Nonce( uint64_t val )
   memcpy( bytes + 4, &val_net, 8 );
 }
 
-uint64_t Nonce::val( void )
+uint64_t Nonce::val( void ) const
 {
   uint64_t ret;
   memcpy( &ret, bytes + 4, 8 );
   return be64toh( ret );
 }
 
-Nonce::Nonce( char *s_bytes, size_t len )
+Nonce::Nonce( const char *s_bytes, size_t len )
 {
   if ( len != 8 ) {
     throw CryptoException( "Nonce representation must be 8 octets long." );
@@ -201,18 +201,18 @@ Nonce::Nonce( char *s_bytes, size_t len )
   memcpy( bytes + 4, s_bytes, 8 );
 }
 
-Message::Message( char *nonce_bytes, size_t nonce_len,
-		  char *text_bytes, size_t text_len )
+Message::Message( const char *nonce_bytes, size_t nonce_len,
+		  const char *text_bytes, size_t text_len )
   : nonce( nonce_bytes, nonce_len ),
-    text( (char *)text_bytes, text_len )
+    text( text_bytes, text_len )
 {}
 
-Message::Message( Nonce s_nonce, string s_text )
+Message::Message( const Nonce & s_nonce, const string & s_text )
   : nonce( s_nonce ),
     text( s_text )
 {}
 
-string Session::encrypt( Message plaintext )
+const string Session::encrypt( const Message & plaintext )
 {
   const size_t pt_len = plaintext.text.size();
   const int ciphertext_len = pt_len + 16;
@@ -262,13 +262,13 @@ string Session::encrypt( Message plaintext )
   return plaintext.nonce.cc_str() + text;
 }
 
-Message Session::decrypt( string ciphertext )
+const Message Session::decrypt( const string & ciphertext )
 {
   if ( ciphertext.size() < 24 ) {
     throw CryptoException( "Ciphertext must contain nonce and tag." );
   }
 
-  char *str = (char *)ciphertext.data();
+  const char *str = ciphertext.data();
 
   int body_len = ciphertext.size() - 8;
   int pt_len = body_len - 16;
@@ -297,7 +297,7 @@ Message Session::decrypt( string ciphertext )
     throw CryptoException( "Packet failed integrity check." );
   }
 
-  Message ret( nonce, string( plaintext_buffer.data(), pt_len ) );
+  const Message ret( nonce, string( plaintext_buffer.data(), pt_len ) );
 
   return ret;
 }

src/crypto/crypto.h

@@ -109,21 +109,21 @@ namespace Crypto {
 
   public:
     Nonce( uint64_t val );
-    Nonce( char *s_bytes, size_t len );
+    Nonce( const char *s_bytes, size_t len );
     
     string cc_str( void ) const { return string( bytes + 4, 8 ); }
     const char *data( void ) const { return bytes; }
-    uint64_t val( void );
+    uint64_t val( void ) const;
   };
   
   class Message {
   public:
-    Nonce nonce;
-    string text;
+    const Nonce nonce;
+    const string text;
     
-    Message( char *nonce_bytes, size_t nonce_len,
-	     char *text_bytes, size_t text_len );
-    Message( Nonce s_nonce, string s_text );
+    Message( const char *nonce_bytes, size_t nonce_len,
+	     const char *text_bytes, size_t text_len );
+    Message( const Nonce & s_nonce, const string & s_text );
   };
   
   class Session {
@@ -145,8 +145,8 @@ namespace Crypto {
     Session( Base64Key s_key );
     ~Session();
     
-    string encrypt( Message plaintext );
-    Message decrypt( string ciphertext );
+    const string encrypt( const Message & plaintext );
+    const Message decrypt( const string & ciphertext );
     
     Session( const Session & );
     Session & operator=( const Session & );