Add support for client-side session resumption

11 files changed, 305 insertions, 167 deletions

diff --git a/doc/examples/tls_client.cpp b/doc/examples/tls_client.cpp
index 275d4b309..1787e8dea 100644
--- a/doc/examples/tls_client.cpp
+++ b/doc/examples/tls_client.cpp
@@ -112,6 +112,82 @@ void process_data(const byte buf[], size_t buf_size, u16bit alert_info)
       printf("%c", buf[i]);
    }
 
+void doit(RandomNumberGenerator& rng,
+          TLS_Policy& policy,
+          TLS_Session_Manager& session_manager,
+          const std::string& host,
+          u16bit port)
+   {
+   int sockfd = connect_to_host(host, port);
+
+   TLS_Client client(std::tr1::bind(socket_write, sockfd, _1, _2),
+                     process_data,
+                     handshake_complete,
+                     session_manager,
+                     policy,
+                     rng,
+                     host);
+
+   fd_set readfds;
+
+   bool version_reported = false;
+
+   while(true)
+      {
+      FD_ZERO(&readfds);
+      FD_SET(sockfd, &readfds);
+      FD_SET(STDIN_FILENO, &readfds);
+
+      ::select(sockfd + 1, &readfds, NULL, NULL, NULL);
+
+      if(client.is_closed())
+         break;
+
+      if(client.is_active() && !version_reported)
+         printf("Negotiated version %04X\n", client.protocol_version());
+
+      if(FD_ISSET(sockfd, &readfds))
+         {
+         byte buf[1024] = { 0 };
+         ssize_t got = read(sockfd, buf, sizeof(buf));
+
+         if(got == 0)
+            {
+            printf("EOF on socket\n");
+            break;
+            }
+         else if(got == -1)
+            {
+            printf("Socket error %d (%s)\n", errno, strerror(errno));
+            continue;
+            }
+
+         //printf("socket read %d\n", got);
+
+         client.received_data(buf, got);
+         }
+      else if(FD_ISSET(STDIN_FILENO, &readfds))
+         {
+         byte buf[1024] = { 0 };
+         ssize_t got = read(STDIN_FILENO, buf, sizeof(buf));
+
+         if(got == 0)
+            {
+            printf("EOF on stdin\n");
+            client.close();
+            break;
+            }
+         else if(got == -1)
+            {
+            printf("Error reading stdin %d (%s)\n", errno, strerror(errno));
+            continue;
+            }
+
+         client.queue_for_sending(buf, got);
+         }
+      }
+   }
+
 int main(int argc, char* argv[])
    {
    if(argc != 2 && argc != 3)
@@ -130,74 +206,9 @@ int main(int argc, char* argv[])
       std::string host = argv[1];
       u32bit port = argc == 3 ? Botan::to_u32bit(argv[2]) : 443;
 
-      int sockfd = connect_to_host(host, port);
-
-      TLS_Client client(std::tr1::bind(socket_write, sockfd, _1, _2),
-                        process_data,
-                        handshake_complete,
-                        session_manager,
-                        policy,
-                        rng,
-                        host);
-
-      fd_set readfds;
-
-      bool version_reported = false;
-
       while(true)
-         {
-         FD_ZERO(&readfds);
-         FD_SET(sockfd, &readfds);
-         FD_SET(STDIN_FILENO, &readfds);
-
-         ::select(sockfd + 1, &readfds, NULL, NULL, NULL);
-
-         if(client.is_closed())
-            break;
-
-         if(client.is_active() && !version_reported)
-            printf("Negotiated version %04X\n", client.protocol_version());
+         doit(rng, policy, session_manager, host, port);
 
-         if(FD_ISSET(sockfd, &readfds))
-            {
-            byte buf[1024] = { 0 };
-            ssize_t got = read(sockfd, buf, sizeof(buf));
-
-            if(got == 0)
-               {
-               printf("EOF on socket\n");
-               break;
-               }
-            else if(got == -1)
-               {
-               printf("Socket error %d (%s)\n", errno, strerror(errno));
-               continue;
-               }
-
-            //printf("socket read %d\n", got);
-
-            client.received_data(buf, got);
-            }
-         else if(FD_ISSET(STDIN_FILENO, &readfds))
-            {
-            byte buf[1024] = { 0 };
-            ssize_t got = read(STDIN_FILENO, buf, sizeof(buf));
-
-            if(got == 0)
-               {
-               printf("EOF on stdin\n");
-               client.close();
-               break;
-               }
-            else if(got == -1)
-               {
-               printf("Error reading stdin %d (%s)\n", errno, strerror(errno));
-               continue;
-               }
-
-            client.queue_for_sending(buf, got);
-            }
-         }
    }
    catch(std::exception& e)
       {
diff --git a/src/tls/hello.cpp b/src/tls/hello.cpp
index fc19f6802..08d8eee8e 100644
--- a/src/tls/hello.cpp
+++ b/src/tls/hello.cpp
@@ -17,7 +17,7 @@ namespace Botan {
 /*
 * Encode and send a Handshake message
 */
-void HandshakeMessage::send(Record_Writer& writer, TLS_Handshake_Hash& hash) const
+void Handshake_Message::send(Record_Writer& writer, TLS_Handshake_Hash& hash) const
    {
    MemoryVector<byte> buf = serialize();
    MemoryVector<byte> send_buf(4);
@@ -86,6 +86,27 @@ Client_Hello::Client_Hello(Record_Writer& writer,
    }
 
 /*
+* Create a new Client Hello message
+*/
+Client_Hello::Client_Hello(Record_Writer& writer,
+                           TLS_Handshake_Hash& hash,
+                           RandomNumberGenerator& rng,
+                           const TLS_Session& session) :
+   c_version(session.version()),
+   sess_id(session.session_id()),
+   c_random(rng.random_vec(32)),
+   requested_hostname(session.sni_hostname()),
+   requested_srp_id(session.srp_identifier()),
+   m_fragment_size(session.fragment_size()),
+   has_secure_renegotiation(session.secure_renegotiation())
+   {
+   suites.push_back(session.ciphersuite());
+   comp_methods.push_back(session.compression_method());
+
+   send(writer, hash);
+   }
+
+/*
 * Serialize a Client Hello message
 */
 MemoryVector<byte> Client_Hello::serialize() const
diff --git a/src/tls/tls_channel.h b/src/tls/tls_channel.h
index 8eca71305..c1e9e1fda 100644
--- a/src/tls/tls_channel.h
+++ b/src/tls/tls_channel.h
@@ -24,9 +24,8 @@ class BOTAN_DLL TLS_Channel
    public:
       /**
       * Inject TLS traffic received from counterparty
-
       * @return a hint as the how many more bytes we need to process the
-                current record (this may be 0 if on a record boundary)
+      *         current record (this may be 0 if on a record boundary)
       */
       virtual size_t received_data(const byte buf[], size_t buf_size);
 
@@ -43,21 +42,23 @@ class BOTAN_DLL TLS_Channel
       /**
       * Send a TLS alert message. If the alert is fatal, the
       * internal state (keys, etc) will be reset
+      * @param level is warning or fatal
+      * @param type is the type of alert
       */
       void alert(Alert_Level level, Alert_Type type);
 
       /**
-      * Is the connection active for sending application data?
+      * @return true iff the connection is active for sending application data
       */
       bool is_active() const { return handshake_completed && !is_closed(); }
 
       /**
-      * Has the connection been definitely closed
+      * @return true iff the connection has been definitely closed
       */
       bool is_closed() const { return connection_closed; }
 
       /**
-      * Return the negotiated version (if session is currently active)
+      * @return negotiated version (if session is currently active)
       */
       Version_Code protocol_version() const;
 
@@ -67,7 +68,7 @@ class BOTAN_DLL TLS_Channel
       virtual void renegotiate() = 0;
 
       /**
-      * Return the certificates of the peer
+      * @return certificate chain of the peer (may be empty)
       */
       std::vector<X509_Certificate> peer_cert_chain() const { return peer_certs; }
 
diff --git a/src/tls/tls_client.cpp b/src/tls/tls_client.cpp
index 1790151f9..9942c2d44 100644
--- a/src/tls/tls_client.cpp
+++ b/src/tls/tls_client.cpp
@@ -8,10 +8,13 @@
 #include <botan/tls_client.h>
 #include <botan/internal/tls_session_key.h>
 #include <botan/internal/tls_handshake_state.h>
+#include <botan/internal/stl_util.h>
 #include <botan/rsa.h>
 #include <botan/dsa.h>
 #include <botan/dh.h>
 
+#include <stdio.h>
+
 namespace Botan {
 
 /*
@@ -24,7 +27,7 @@ TLS_Client::TLS_Client(std::tr1::function<void (const byte[], size_t)> output_fn
                        const TLS_Policy& policy,
                        RandomNumberGenerator& rng,
                        const std::string& hostname,
-                       const std::string& srp_username) :
+                       const std::string& srp_identifier) :
    TLS_Channel(output_fn, proc_fn, handshake_fn),
    policy(policy),
    rng(rng),
@@ -34,13 +37,36 @@ TLS_Client::TLS_Client(std::tr1::function<void (const byte[], size_t)> output_fn
 
    state = new Handshake_State;
    state->set_expected_next(SERVER_HELLO);
-   state->client_hello = new Client_Hello(writer,
-                                          state->hash,
-                                          policy,
-                                          rng,
-                                          secure_renegotiation.for_client_hello(),
-                                          hostname,
-                                          srp_username);
+
+   if(hostname != "")
+      {
+      TLS_Session session_info;
+      if(session_manager.load_from_host_info(hostname, 0, session_info))
+         {
+         if(session_info.srp_identifier() == srp_identifier)
+            {
+            state->client_hello = new Client_Hello(
+               writer,
+               state->hash,
+               rng,
+               session_info);
+
+            state->resume_master_secret = session_info.master_secret();
+            }
+         }
+      }
+
+   if(!state->client_hello) // not resuming
+      {
+      state->client_hello = new Client_Hello(
+         writer,
+         state->hash,
+         policy,
+         rng,
+         secure_renegotiation.for_client_hello(),
+         hostname,
+         srp_identifier);
+      }
 
    secure_renegotiation.update(state->client_hello);
    }
@@ -128,19 +154,14 @@ void TLS_Client::process_handshake_msg(Handshake_Type type,
                              "TLS_Client: Server replied with bad ciphersuite");
          }
 
-      state->version = state->server_hello->version();
-
-      if(state->version > state->client_hello->version())
+      if(!value_exists(state->client_hello->compression_methods(),
+                       state->server_hello->compression_method()))
          {
          throw TLS_Exception(HANDSHAKE_FAILURE,
-                             "TLS_Client: Server replied with bad version");
+                             "TLS_Client: Server replied with bad compression method");
          }
 
-      if(state->version < policy.min_version())
-         {
-         throw TLS_Exception(PROTOCOL_VERSION,
-                             "TLS_Client: Server is too old for specified policy");
-         }
+      state->version = state->server_hello->version();
 
       writer.set_version(state->version);
       reader.set_version(state->version);
@@ -149,20 +170,56 @@ void TLS_Client::process_handshake_msg(Handshake_Type type,
 
       state->suite = TLS_Cipher_Suite(state->server_hello->ciphersuite());
 
-      // if resuming, next is HANDSHAKE_CCS
-
-      if(state->suite.sig_type() != TLS_ALGO_SIGNER_ANON)
-         {
-         state->set_expected_next(CERTIFICATE);
-         }
-      else if(state->suite.kex_type() != TLS_ALGO_KEYEXCH_NOKEX)
+      if(!state->server_hello->session_id().empty() &&
+         (state->server_hello->session_id() == state->client_hello->session_id()))
          {
-         state->set_expected_next(SERVER_KEX);
+         // successful resumption
+
+         /*
+         In this case, we offered the original session and the server
+         must resume with it
+         */
+         if(state->server_hello->version() != state->client_hello->version())
+            throw TLS_Exception(HANDSHAKE_FAILURE,
+                                "Server resumed session but with wrong version");
+
+         state->keys = SessionKeys(state->suite, state->version,
+                                   state->resume_master_secret,
+                                   state->client_hello->random(),
+                                   state->server_hello->random(),
+                                   true);
+
+         state->set_expected_next(HANDSHAKE_CCS);
          }
       else
          {
-         state->set_expected_next(CERTIFICATE_REQUEST); // optional
-         state->set_expected_next(SERVER_HELLO_DONE);
+         // new session
+
+         if(state->version > state->client_hello->version())
+            {
+            throw TLS_Exception(HANDSHAKE_FAILURE,
+                                "TLS_Client: Server replied with bad version");
+            }
+
+         if(state->version < policy.min_version())
+            {
+            throw TLS_Exception(PROTOCOL_VERSION,
+                                "TLS_Client: Server is too old for specified policy");
+            }
+
+         if(state->suite.sig_type() != TLS_ALGO_SIGNER_ANON)
+            {
+            state->set_expected_next(CERTIFICATE);
+            }
+         else if(state->suite.kex_type() != TLS_ALGO_KEYEXCH_NOKEX)
+            {
+            state->set_expected_next(SERVER_KEX);
+            }
+         else
+            {
+            state->set_expected_next(CERTIFICATE_REQUEST); // optional
+            state->set_expected_next(SERVER_HELLO_DONE);
+            }
          }
       }
    else if(type == CERTIFICATE)
@@ -308,6 +365,38 @@ void TLS_Client::process_handshake_msg(Handshake_Type type,
          throw TLS_Exception(DECRYPT_ERROR,
                              "Finished message didn't verify");
 
+      state->hash.update(type, contents);
+
+      if(!state->client_finished) // session resume case
+         {
+         writer.send(CHANGE_CIPHER_SPEC, 1);
+
+         writer.activate(state->suite, state->keys, CLIENT);
+
+         state->client_finished = new Finished(writer, state->hash,
+                                               state->version, CLIENT,
+                                               state->keys.master_secret());
+         }
+
+      TLS_Session session_info(
+         state->server_hello->session_id(),
+         state->keys.master_secret(),
+         state->server_hello->version(),
+         state->server_hello->ciphersuite(),
+         state->server_hello->compression_method(),
+         CLIENT,
+         secure_renegotiation.supported(),
+         state->server_hello->fragment_size(),
+         peer_certs,
+         state->client_hello->sni_hostname(),
+         ""
+         );
+
+      session_manager.save(session_info);
+
+      if(handshake_fn)
+         handshake_fn(session_info);
+
       secure_renegotiation.update(state->client_finished, state->server_finished);
 
       delete state;
diff --git a/src/tls/tls_client.h b/src/tls/tls_client.h
index 75a85f74d..0f654a40f 100644
--- a/src/tls/tls_client.h
+++ b/src/tls/tls_client.h
@@ -25,7 +25,7 @@ class BOTAN_DLL TLS_Client : public TLS_Channel
       * @param socket_output_fn is called with data for the outbound socket
       * @param proc_fn is called when new data (application or alerts) is received
       * @param handshake_complete is called when a handshake is completed
-      * @param session_manager manages session resumption
+      * @param session_manager manages session state
       * @param policy specifies other connection policy information
       * @param rng a random number generator
       * @param servername the server's DNS name, if known
diff --git a/src/tls/tls_handshake_state.h b/src/tls/tls_handshake_state.h
index 1602ca17c..f57538478 100644
--- a/src/tls/tls_handshake_state.h
+++ b/src/tls/tls_handshake_state.h
@@ -50,6 +50,11 @@ class Handshake_State
 
       SecureQueue queue;
 
+      /*
+      * Only used by clients for session resumption
+      */
+      SecureVector<byte> resume_master_secret;
+
       Version_Code version;
    private:
       u32bit hand_expecting_mask, hand_received_mask;
diff --git a/src/tls/tls_messages.h b/src/tls/tls_messages.h
index 2d66dfa11..f0620003b 100644
--- a/src/tls/tls_messages.h
+++ b/src/tls/tls_messages.h
@@ -9,6 +9,7 @@
 #define BOTAN_TLS_MESSAGES_H__
 
 #include <botan/internal/tls_handshake_hash.h>
+#include <botan/tls_session.h>
 #include <botan/tls_policy.h>
 #include <botan/tls_magic.h>
 #include <botan/tls_suites.h>
@@ -25,16 +26,16 @@ class Record_Reader;
 /**
 * TLS Handshake Message Base Class
 */
-class HandshakeMessage
+class Handshake_Message
    {
    public:
       void send(Record_Writer& writer, TLS_Handshake_Hash& hash) const;
 
       virtual Handshake_Type type() const = 0;
 
-      virtual ~HandshakeMessage() {}
+      virtual ~Handshake_Message() {}
    private:
-      HandshakeMessage& operator=(const HandshakeMessage&) { return (*this); }
+      Handshake_Message& operator=(const Handshake_Message&) { return (*this); }
       virtual MemoryVector<byte> serialize() const = 0;
       virtual void deserialize(const MemoryRegion<byte>&) = 0;
    };
@@ -42,7 +43,7 @@ class HandshakeMessage
 /**
 * Client Hello Message
 */
-class Client_Hello : public HandshakeMessage
+class Client_Hello : public Handshake_Message
    {
    public:
       Handshake_Type type() const { return CLIENT_HELLO; }
@@ -82,6 +83,11 @@ class Client_Hello : public HandshakeMessage
                    const std::string& hostname = "",
                    const std::string& srp_identifier = "");
 
+      Client_Hello(Record_Writer& writer,
+                   TLS_Handshake_Hash& hash,
+                   RandomNumberGenerator& rng,
+                   const TLS_Session& resumed_session);
+
       Client_Hello(const MemoryRegion<byte>& buf,
                    Handshake_Type type)
          {
@@ -111,7 +117,7 @@ class Client_Hello : public HandshakeMessage
 /**
 * Server Hello Message
 */
-class Server_Hello : public HandshakeMessage
+class Server_Hello : public Handshake_Message
    {
    public:
       Handshake_Type type() const { return SERVER_HELLO; }
@@ -176,7 +182,7 @@ class Server_Hello : public HandshakeMessage
 /**
 * Client Key Exchange Message
 */
-class Client_Key_Exchange : public HandshakeMessage
+class Client_Key_Exchange : public Handshake_Message
    {
    public:
       Handshake_Type type() const { return CLIENT_KEX; }
@@ -209,7 +215,7 @@ class Client_Key_Exchange : public HandshakeMessage
 /**
 * Certificate Message
 */
-class Certificate : public HandshakeMessage
+class Certificate : public Handshake_Message
    {
    public:
       Handshake_Type type() const { return CERTIFICATE; }
@@ -232,7 +238,7 @@ class Certificate : public HandshakeMessage
 /**
 * Certificate Request Message
 */
-class Certificate_Req : public HandshakeMessage
+class Certificate_Req : public Handshake_Message
    {
    public:
       Handshake_Type type() const { return CERTIFICATE_REQUEST; }
@@ -258,7 +264,7 @@ class Certificate_Req : public HandshakeMessage
 /**
 * Certificate Verify Message
 */
-class Certificate_Verify : public HandshakeMessage
+class Certificate_Verify : public Handshake_Message
    {
    public:
       Handshake_Type type() const { return CERTIFICATE_VERIFY; }
@@ -291,7 +297,7 @@ class Certificate_Verify : public HandshakeMessage
 /**
 * Finished Message
 */
-class Finished : public HandshakeMessage
+class Finished : public Handshake_Message
    {
    public:
       Handshake_Type type() const { return FINISHED; }
@@ -327,7 +333,7 @@ class Finished : public HandshakeMessage
 /**
 * Hello Request Message
 */
-class Hello_Request : public HandshakeMessage
+class Hello_Request : public Handshake_Message
    {
    public:
       Handshake_Type type() const { return HELLO_REQUEST; }
@@ -342,7 +348,7 @@ class Hello_Request : public HandshakeMessage
 /**
 * Server Key Exchange Message
 */
-class Server_Key_Exchange : public HandshakeMessage
+class Server_Key_Exchange : public Handshake_Message
    {
    public:
       Handshake_Type type() const { return SERVER_KEX; }
@@ -373,7 +379,7 @@ class Server_Key_Exchange : public HandshakeMessage
 /**
 * Server Hello Done Message
 */
-class Server_Hello_Done : public HandshakeMessage
+class Server_Hello_Done : public Handshake_Message
    {
    public:
       Handshake_Type type() const { return SERVER_HELLO_DONE; }
diff --git a/src/tls/tls_server.cpp b/src/tls/tls_server.cpp
index f0d1fb361..0e2e173cf 100644
--- a/src/tls/tls_server.cpp
+++ b/src/tls/tls_server.cpp
@@ -12,6 +12,8 @@
 #include <botan/rsa.h>
 #include <botan/dh.h>
 
+#include <stdio.h>
+
 namespace Botan {
 
 namespace {
@@ -180,6 +182,8 @@ void TLS_Server::process_handshake_msg(Handshake_Type type,
       if(resuming)
          {
          // resume session
+
+         printf("Resuming a session\n");
          state->server_hello = new Server_Hello(
             writer,
             state->hash,
@@ -377,27 +381,27 @@ void TLS_Server::process_handshake_msg(Handshake_Type type,
 
          if(state->client_certs && state->client_verify)
             peer_certs = state->client_certs->cert_chain();
-
-         TLS_Session session_info(
-            state->server_hello->session_id(),
-            state->keys.master_secret(),
-            state->server_hello->version(),
-            state->server_hello->ciphersuite(),
-            state->server_hello->compression_method(),
-            SERVER,
-            secure_renegotiation.supported(),
-            state->server_hello->fragment_size(),
-            peer_certs,
-            client_requested_hostname,
-            ""
-            );
-
-         session_manager.save(session_info);
-
-         if(handshake_fn)
-            handshake_fn(session_info);
          }
 
+      TLS_Session session_info(
+         state->server_hello->session_id(),
+         state->keys.master_secret(),
+         state->server_hello->version(),
+         state->server_hello->ciphersuite(),
+         state->server_hello->compression_method(),
+         SERVER,
+         secure_renegotiation.supported(),
+         state->server_hello->fragment_size(),
+         peer_certs,
+         client_requested_hostname,
+         ""
+         );
+
+      session_manager.save(session_info);
+
+      if(handshake_fn)
+         handshake_fn(session_info);
+
       secure_renegotiation.update(state->client_finished,
                                   state->server_finished);
 
diff --git a/src/tls/tls_session.h b/src/tls/tls_session.h
index c713efc87..b4b3861ed 100644
--- a/src/tls/tls_session.h
+++ b/src/tls/tls_session.h
@@ -38,16 +38,16 @@ class BOTAN_DLL TLS_Session
       * New session (sets session start time)
       */
       TLS_Session(const MemoryRegion<byte>& session_id,
-                         const MemoryRegion<byte>& master_secret,
-                         Version_Code version,
-                         u16bit ciphersuite,
-                         byte compression_method,
-                         Connection_Side side,
-                         bool secure_renegotiation_supported,
-                         size_t fragment_size,
-                         const std::vector<X509_Certificate>& peer_certs,
-                         const std::string& sni_hostname = "",
-                         const std::string& srp_identifier = "");
+                  const MemoryRegion<byte>& master_secret,
+                  Version_Code version,
+                  u16bit ciphersuite,
+                  byte compression_method,
+                  Connection_Side side,
+                  bool secure_renegotiation_supported,
+                  size_t fragment_size,
+                  const std::vector<X509_Certificate>& peer_certs,
+                  const std::string& sni_hostname = "",
+                  const std::string& srp_identifier = "");
 
       /**
       * Load a session from BER (created by BER_encode)
@@ -111,9 +111,9 @@ class BOTAN_DLL TLS_Session
       size_t fragment_size() const { return m_fragment_size; }
 
       /**
-      * Is secure negotiation supported?
+      * Is secure renegotiation supported?
       */
-      bool secure_negotiation() const
+      bool secure_renegotiation() const
          { return m_secure_renegotiation_supported; }
 
       /**
diff --git a/src/tls/tls_session_manager.cpp b/src/tls/tls_session_manager.cpp
index 7503b7c28..4a0126fc0 100644
--- a/src/tls/tls_session_manager.cpp
+++ b/src/tls/tls_session_manager.cpp
@@ -9,6 +9,8 @@
 #include <botan/hex.h>
 #include <botan/time.h>
 
+#include <stdio.h>
+
 namespace Botan {
 
 bool TLS_Session_Manager_In_Memory::load_from_session_str(
@@ -21,7 +23,7 @@ bool TLS_Session_Manager_In_Memory::load_from_session_str(
 
    // session has expired, remove it
    const u64bit now = system_time();
-   if(i->second.start_time() + session_lifetime >= now)
+   if(i->second.start_time() + session_lifetime < now)
       {
       sessions.erase(i);
       return false;
@@ -32,7 +34,7 @@ bool TLS_Session_Manager_In_Memory::load_from_session_str(
    }
 
 bool TLS_Session_Manager_In_Memory::load_from_session_id(
-   const MemoryVector<byte>& session_id, TLS_Session& session)
+   const MemoryRegion<byte>& session_id, TLS_Session& session)
    {
    return load_from_session_str(hex_encode(session_id), session);
    }
@@ -60,7 +62,7 @@ bool TLS_Session_Manager_In_Memory::load_from_host_info(
    }
 
 void TLS_Session_Manager_In_Memory::remove_entry(
-   const MemoryVector<byte>& session_id)
+   const MemoryRegion<byte>& session_id)
    {
    std::map<std::string, TLS_Session>::iterator i =
       sessions.find(hex_encode(session_id));
diff --git a/src/tls/tls_session_manager.h b/src/tls/tls_session_manager.h
index b30de7364..289b76a3b 100644
--- a/src/tls/tls_session_manager.h
+++ b/src/tls/tls_session_manager.h
@@ -28,39 +28,38 @@ class BOTAN_DLL TLS_Session_Manager
       /**
       * Try to load a saved session (server side)
       * @param session_id the session identifier we are trying to resume
-      * @param params will be set to the saved session data (if found),
+      * @param session will be set to the saved session data (if found),
                or not modified if not found
-      * @return true if params was modified
+      * @return true if session was modified
       */
-      virtual bool load_from_session_id(const MemoryVector<byte>& session_id,
-                                        TLS_Session& params) = 0;
+      virtual bool load_from_session_id(const MemoryRegion<byte>& session_id,
+                                        TLS_Session& session) = 0;
 
       /**
       * Try to load a saved session (client side)
       * @param hostname of the host we are connecting to
       * @param port the port number if we know it, or 0 if unknown
-      * @param params will be set to the saved session data (if found),
+      * @param session will be set to the saved session data (if found),
                or not modified if not found
-      * @return true if params was modified
+      * @return true if session was modified
       */
       virtual bool load_from_host_info(const std::string& hostname, u16bit port,
-                                       TLS_Session& params) = 0;
+                                       TLS_Session& session) = 0;
 
       /**
-      * Remove this session id from the cache
+      * Remove this session id from the cache, if it exists
       */
-      virtual void remove_entry(const MemoryVector<byte>& session_id) = 0;
+      virtual void remove_entry(const MemoryRegion<byte>& session_id) = 0;
 
       /**
       * Save a session on a best effort basis; the manager may not in
-      * fact be able to save the session for whatever reason, this is
+      * fact be able to save the session for whatever reason; this is
       * not an error. Caller cannot assume that calling save followed
-      * immediately by find will result in a successful lookup.
+      * immediately by load_from_* will result in a successful lookup.
       *
-      * @param session_id the session identifier
-      * @param params to save
+      * @param session to save
       */
-      virtual void save(const TLS_Session& params) = 0;
+      virtual void save(const TLS_Session& session) = 0;
 
       virtual ~TLS_Session_Manager() {}
    };
@@ -86,19 +85,19 @@ class BOTAN_DLL TLS_Session_Manager_In_Memory : public TLS_Session_Manager
          session_lifetime(session_lifetime)
             {}
 
-      bool load_from_session_id(const MemoryVector<byte>& session_id,
-                                TLS_Session& params);
+      bool load_from_session_id(const MemoryRegion<byte>& session_id,
+                                TLS_Session& session);
 
       bool load_from_host_info(const std::string& hostname, u16bit port,
-                               TLS_Session& params);
+                               TLS_Session& session);
 
-      void remove_entry(const MemoryVector<byte>& session_id);
+      void remove_entry(const MemoryRegion<byte>& session_id);
 
       void save(const TLS_Session& session_data);
 
    private:
       bool load_from_session_str(const std::string& session_str,
-                                 TLS_Session& params);
+                                 TLS_Session& session);
 
       size_t max_sessions, session_lifetime;