From d96b4425121bfeb122d90c73405f951b220a839c Mon Sep 17 00:00:00 2001
From: lloyd <lloyd@randombit.net>
Date: Fri, 11 Apr 2014 22:13:07 +0000
Subject: Verify that the server did not send any extension that the client
 didn't offer. Previously the client only checked a couple of special cases.

---
 src/lib/tls/tls_client.cpp     | 22 ++++++++++++----------
 src/lib/tls/tls_extensions.cpp |  8 ++++++++
 src/lib/tls/tls_extensions.h   |  3 +++
 src/lib/tls/tls_messages.h     |  6 ++++++
 src/lib/tls/tls_policy.cpp     | 10 ++++++++++
 src/lib/tls/tls_policy.h       |  4 ++--
 6 files changed, 41 insertions(+), 12 deletions(-)

(limited to 'src/lib')

diff --git a/src/lib/tls/tls_client.cpp b/src/lib/tls/tls_client.cpp
index 2bbe51fd7..3de9130d4 100644
--- a/src/lib/tls/tls_client.cpp
+++ b/src/lib/tls/tls_client.cpp
@@ -209,18 +209,20 @@ void Client::process_handshake_msg(const Handshake_State* active_state,
                              "Server replied with compression method we didn't send");
          }
 
-      if(!state.client_hello()->next_protocol_notification() &&
-         state.server_hello()->next_protocol_notification())
-         {
-         throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
-                             "Server sent next protocol but we didn't request it");
-         }
+      auto client_extn = state.client_hello()->extension_types();
+      auto server_extn = state.server_hello()->extension_types();
 
-      if(state.server_hello()->supports_session_ticket())
+      std::vector<Handshake_Extension_Type> diff;
+
+      std::set_difference(server_extn.begin(), server_extn.end(),
+                          client_extn.begin(), server_extn.end(),
+                          std::back_inserter(diff));
+
+      for(auto i : diff)
          {
-         if(!state.client_hello()->supports_session_ticket())
-            throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
-                                "Server sent session ticket extension but we did not");
+         throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
+                             "Server sent extension " + std::to_string(i) +
+                             " but we did not request it");
          }
 
       state.set_version(state.server_hello()->version());
diff --git a/src/lib/tls/tls_extensions.cpp b/src/lib/tls/tls_extensions.cpp
index 1ae9f1749..0860006e6 100644
--- a/src/lib/tls/tls_extensions.cpp
+++ b/src/lib/tls/tls_extensions.cpp
@@ -115,6 +115,14 @@ std::vector<byte> Extensions::serialize() const
    return buf;
    }
 
+std::set<Handshake_Extension_Type> Extensions::extension_types() const
+   {
+   std::set<Handshake_Extension_Type> offers;
+   for(auto i = extensions.begin(); i != extensions.end(); ++i)
+      offers.insert(i->first);
+   return offers;
+   }
+
 Server_Name_Indicator::Server_Name_Indicator(TLS_Data_Reader& reader,
                                              u16bit extension_size)
    {
diff --git a/src/lib/tls/tls_extensions.h b/src/lib/tls/tls_extensions.h
index caa389ded..a88938eba 100644
--- a/src/lib/tls/tls_extensions.h
+++ b/src/lib/tls/tls_extensions.h
@@ -13,6 +13,7 @@
 #include <vector>
 #include <string>
 #include <map>
+#include <set>
 
 namespace Botan {
 
@@ -357,6 +358,8 @@ class Heartbeat_Support_Indicator : public Extension
 class Extensions
    {
    public:
+      std::set<Handshake_Extension_Type> extension_types() const;
+
       template<typename T>
       T* get() const
          {
diff --git a/src/lib/tls/tls_messages.h b/src/lib/tls/tls_messages.h
index a616b0def..f3bf8fad2 100644
--- a/src/lib/tls/tls_messages.h
+++ b/src/lib/tls/tls_messages.h
@@ -149,6 +149,9 @@ class Client_Hello : public Handshake_Message
 
       void update_hello_cookie(const Hello_Verify_Request& hello_verify);
 
+      std::set<Handshake_Extension_Type> extension_types() const
+         { return m_extensions.extension_types(); }
+
       Client_Hello(Handshake_IO& io,
                    Handshake_Hash& hash,
                    Protocol_Version version,
@@ -251,6 +254,9 @@ class Server_Hello : public Handshake_Message
          return false;
          }
 
+      std::set<Handshake_Extension_Type> extension_types() const
+         { return m_extensions.extension_types(); }
+
       Server_Hello(Handshake_IO& io,
                    Handshake_Hash& hash,
                    const Policy& policy,
diff --git a/src/lib/tls/tls_policy.cpp b/src/lib/tls/tls_policy.cpp
index 05251e186..c1f2c311c 100644
--- a/src/lib/tls/tls_policy.cpp
+++ b/src/lib/tls/tls_policy.cpp
@@ -153,6 +153,16 @@ bool Policy::acceptable_ciphersuite(const Ciphersuite&) const
    return true;
    }
 
+bool Policy::negotiate_heartbeat_support() const
+   {
+   return false;
+   }
+
+bool Policy::allow_server_initiated_renegotiation() const
+   {
+   return true;
+   }
+
 namespace {
 
 class Ciphersuite_Preference_Ordering
diff --git a/src/lib/tls/tls_policy.h b/src/lib/tls/tls_policy.h
index 5b205dfeb..9aaa1745c 100644
--- a/src/lib/tls/tls_policy.h
+++ b/src/lib/tls/tls_policy.h
@@ -78,7 +78,7 @@ class BOTAN_DLL Policy
       /**
       * Attempt to negotiate the use of the heartbeat extension
       */
-      virtual bool negotiate_heartbeat_support() const { return false; }
+      virtual bool negotiate_heartbeat_support() const;
 
       /**
       * Allow renegotiation even if the counterparty doesn't
@@ -92,7 +92,7 @@ class BOTAN_DLL Policy
       /**
       * Allow servers to initiate a new handshake
       */
-      virtual bool allow_server_initiated_renegotiation() const { return true; }
+      virtual bool allow_server_initiated_renegotiation() const;
 
       /**
       * Return the group to use for ephemeral Diffie-Hellman key agreement
-- 
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