# 
# patch "ChangeLog"
#  from [f6962ae1e54db8ef7df9d8daf40c08415d3b60d7]
#    to [a7d78e5b4cb7e07bdf3aba7a92ea4fc609a03316]
# 
# patch "Makefile.am"
#  from [8f57b338067b43d1d1ae5de118323a6c67f6be7d]
#    to [f2cebcb5b9a6cf9ca254765464af8cccc11da225]
# 
# patch "netcmd.cc"
#  from [7308c12cecebbd725ddca9ebfa94bd9a6e1efdea]
#    to [f1f30a4a9655a95d2007a309a0d4a618229dcdca]
# 
# patch "netcmd.hh"
#  from [db259c3bbd1fdc984b3cae3fb90128f7b0e461e5]
#    to [f5565d11c6b2db20139d0aab07a5b8bfe37b3cd8]
# 
# patch "netsync.cc"
#  from [a216c4dc84981cff4cdf26cc45303c46a16054fd]
#    to [c0daeb05b828a4e64c62379ceb8f2113c3f8b1ae]
# 
# patch "transforms.hh"
#  from [beb9c11a04e735f442928aea2e984834c8573c8d]
#    to [9fb4f54ab766397cc5a40885457b2ddbabbb300f]
# 
--- ChangeLog
+++ ChangeLog
@@ -1,3 +1,15 @@
+2005-06-26  Matt Johnston  <address@hidden>
+
+	* netcmd.cc (netcmd::read, netcmd::write): change to using a HMACs 
+	chained by including the previous HMAC in the input data, rather
+	than altering the key each time.
+	* netcmd.cc ({read,write}_{data,delta}_cmd): use encode_gzip/decode_gzip
+	  rather than raw xform.
+	* hmac.{cc,hh}: new chained_hmac abstraction
+	* Makefile.in: add them
+	* netsync.cc: each session keeps a chained_hmac for read/write
+	* transforms.hh: add a string variant for encode_gzip
+
 2005-06-25  Nathaniel Smith  <address@hidden>
 
 	* netsync.cc: Tweak comment.
--- Makefile.am
+++ Makefile.am
@@ -40,6 +40,7 @@
          selectors.cc selectors.hh					\
          annotate.cc annotate.hh					\
          restrictions.cc restrictions.hh				\
+         hmac.cc hmac.hh                  \
 									\
 	 cleanup.hh unit_tests.hh interner.hh				\
          cycle_detector.hh randomfile.hh adler32.hh quick_alloc.hh	\
--- netcmd.cc
+++ netcmd.cc
@@ -7,10 +7,6 @@
 #include <vector>
 #include <utility>
 
-#include "cryptopp/gzip.h"
-#include "cryptopp/hmac.h"
-#include "cryptopp/sha.h"
-
 #include "adler32.hh"
 #include "constants.hh"
 #include "netcmd.hh"
@@ -18,6 +14,7 @@
 #include "numeric_vocab.hh"
 #include "sanity.hh"
 #include "transforms.hh"
+#include "hmac.hh"
 
 using namespace std;
 using namespace boost;
@@ -68,34 +65,19 @@
 }
   
 void 
-netcmd::write(string & out, netsync_session_key const & key,
-              netsync_hmac_value & hmac_val) const
+netcmd::write(string & out, chained_hmac & hmac) const
 {
   size_t oldlen = out.size();
   out += static_cast<char>(version);
   out += static_cast<char>(cmd_code);
   insert_variable_length_string(payload, out);
 
-  I(key().size() == CryptoPP::SHA::DIGESTSIZE);
-  I(key().size() == hmac_val().size());
-  byte keybuf[CryptoPP::SHA::DIGESTSIZE];
-  for (size_t i = 0; i < sizeof(keybuf); i++)
-    {
-      keybuf[i] = key()[i] ^ hmac_val()[i];
-    }
-  CryptoPP::HMAC<CryptoPP::SHA> hmac(keybuf, sizeof(keybuf));
-  char digest[CryptoPP::SHA::DIGESTSIZE];
-  hmac.CalculateDigest(reinterpret_cast<byte *>(digest),
-                       reinterpret_cast<const byte *>(out.data() + oldlen),
-                       out.size() - oldlen);
-  string digest_str(digest, sizeof(digest));
-  hmac_val = netsync_hmac_value(digest_str);
-  out.append(digest_str);
+  string digest = hmac.process(out, oldlen);
+  out.append(digest);
 }
 
 bool 
-netcmd::read(string & inbuf, netsync_session_key const & key,
-             netsync_hmac_value & hmac_val)
+netcmd::read(string & inbuf, chained_hmac & hmac)
 {
   size_t pos = 0;
 
@@ -142,15 +124,19 @@
     throw bad_decode(F("oversized payload of '%d' bytes") % payload_len);
   
   // there might not be enough data yet in the input buffer
-  if (inbuf.size() < pos + payload_len + CryptoPP::SHA::DIGESTSIZE)
+  if (inbuf.size() < pos + payload_len + constants::netsync_hmac_value_length_in_bytes)
     {
-      inbuf.reserve(pos + payload_len + CryptoPP::SHA::DIGESTSIZE + constants::bufsz);
+      inbuf.reserve(pos + payload_len + constants::netsync_hmac_value_length_in_bytes + constants::bufsz);
       return false;
     }
 
 //  out.payload = extract_substring(inbuf, pos, payload_len, "netcmd payload");
   // Do this ourselves, so we can swap the strings instead of copying.
   require_bytes(inbuf, pos, payload_len, "netcmd payload");
+
+  // grab it before the data gets munged
+  string digest = hmac.process(inbuf, 0, pos + payload_len);
+
   payload = inbuf.substr(pos + payload_len);
   inbuf.erase(pos + payload_len, inbuf.npos);
   inbuf.swap(payload);
@@ -158,26 +144,13 @@
   pos = 0;
 
   // they might have given us bogus data
-  string cmd_digest = extract_substring(inbuf, pos, CryptoPP::SHA::DIGESTSIZE,
+  string cmd_digest = extract_substring(inbuf, pos, 
+      constants::netsync_hmac_value_length_in_bytes,
                                         "netcmd HMAC");
   inbuf.erase(0, pos);
-  I(key().size() == CryptoPP::SHA::DIGESTSIZE);
-  I(key().size() == hmac_val().size());
-  byte keybuf[CryptoPP::SHA::DIGESTSIZE];
-  for (size_t i = 0; i < sizeof(keybuf); i++)
-    {
-      keybuf[i] = key()[i] ^ hmac_val()[i];
-    }
-  CryptoPP::HMAC<CryptoPP::SHA> hmac(keybuf, sizeof(keybuf));
-  char digest_buf[CryptoPP::SHA::DIGESTSIZE];
-  hmac.CalculateDigest(reinterpret_cast<byte *>(digest_buf),
-                       reinterpret_cast<const byte *>(payload.data()),
-                       payload.size());
-  string digest(digest_buf, sizeof(digest_buf));
   if (cmd_digest != digest)
     throw bad_decode(F("bad HMAC %s vs. %s") % encode_hexenc(cmd_digest)
                      % encode_hexenc(digest));
-  hmac_val = netsync_hmac_value(digest);
   payload.erase(0, payload_pos);
 
   return true;    
@@ -445,7 +418,13 @@
   extract_variable_length_string(payload, dat, pos,
                                   "data netcmd, data payload");
   if (compressed_p == 1)
-    dat = xform<CryptoPP::Gunzip>(dat);
+  {
+    gzip<data> zdat;
+    data tdat;
+    zdat.swap(dat);
+    decode_gzip(zdat, tdat);
+    tdat.swap(dat);
+  }
   assert_end_of_buffer(payload, pos, "data netcmd payload");
 }
 
@@ -460,8 +439,10 @@
   payload += item();
   if (dat.size() > constants::netcmd_minimum_bytes_to_bother_with_gzip)
     {
+      gzip<data> zdat;
+      encode_gzip(dat, zdat);
       string tmp;
-      tmp = xform<CryptoPP::Gzip>(dat);
+      zdat.swap(tmp);
       payload += static_cast<char>(1); // compressed flag
       insert_variable_length_string(tmp, payload);
     }
@@ -493,8 +474,14 @@
   extract_variable_length_string(payload, tmp, pos,
                                  "delta netcmd, delta payload");
   if (compressed_p == 1)
-    tmp = xform<CryptoPP::Gunzip>(tmp);
-  del = delta(tmp);
+    {
+      gzip<delta> zdel(tmp);
+      decode_gzip(zdel, del);
+    }
+  else
+    {
+      del = tmp;
+    }
   assert_end_of_buffer(payload, pos, "delta netcmd payload");
 }
 
@@ -510,16 +497,19 @@
   payload += base();
   payload += ident();
 
-  string tmp = del();
+  string tmp;
 
   if (tmp.size() > constants::netcmd_minimum_bytes_to_bother_with_gzip)
     {
       payload += static_cast<char>(1); // compressed flag
-      tmp = xform<CryptoPP::Gzip>(tmp);
+      gzip<delta> zdel;
+      encode_gzip(del, zdel);
+      tmp = zdel();
     }
   else
     {
       payload += static_cast<char>(0); // compressed flag       
+      tmp = del();
     }
   I(tmp.size() <= constants::netcmd_payload_limit);
   insert_variable_length_string(tmp, payload);
--- netcmd.hh
+++ netcmd.hh
@@ -12,6 +12,7 @@
 #include "merkle_tree.hh"
 #include "numeric_vocab.hh"
 #include "vocab.hh"
+#include "hmac.hh"
 
 typedef enum 
   { 
@@ -63,10 +64,9 @@
 
   // basic cmd i/o (including checksums)
   void write(std::string & out,
-             netsync_session_key const & key,
-             netsync_hmac_value & hmac_val) const;
+             chained_hmac & hmac) const;
   bool read(std::string & inbuf,
-            netsync_session_key const & key, netsync_hmac_value & hmac_val);
+            chained_hmac & hmac);
 
   // i/o functions for each type of command payload
   void read_error_cmd(std::string & errmsg) const;
--- netsync.cc
+++ netsync.cc
@@ -32,6 +32,7 @@
 #include "xdelta.hh"
 #include "epoch.hh"
 #include "platform.hh"
+#include "hmac.hh"
 
 #include "cryptopp/osrng.h"
 
@@ -271,8 +272,8 @@
   id remote_peer_key_hash;
   rsa_keypair_id remote_peer_key_name;
   netsync_session_key session_key;
-  netsync_hmac_value read_hmac;
-  netsync_hmac_value write_hmac;
+  chained_hmac read_hmac;
+  chained_hmac write_hmac;
   bool authenticated;
 
   time_t last_io_time;
@@ -321,6 +322,8 @@
   id mk_nonce();
   void mark_recent_io();
 
+  void set_session_key(string const & key);
+
   void setup_client_tickers();
 
   bool done_all_refinements();
@@ -629,6 +632,14 @@
 }
 
 void
+session::set_session_key(string const & key)
+{
+  session_key = netsync_session_key(key);
+  read_hmac.set_key(session_key);
+  write_hmac.set_key(session_key);
+}
+
+void
 session::setup_client_tickers()
 {
   byte_in_ticker.reset(new ticker("bytes in", ">", 1024, true));
@@ -777,7 +788,7 @@
 session::write_netcmd_and_try_flush(netcmd const & cmd)
 {
   if (!encountered_error)
-    cmd.write(outbuf, session_key, write_hmac);
+    cmd.write(outbuf, write_hmac);
   else
     L(F("dropping outgoing netcmd (because we're in error unwind mode)\n"));
   // FIXME: this helps keep the protocol pipeline full but it seems to
@@ -1422,7 +1433,7 @@
               nonce2(), hmac_key_encrypted);
   cmd.write_anonymous_cmd(role, pattern, hmac_key_encrypted);
   write_netcmd_and_try_flush(cmd);
-  session_key = netsync_session_key(nonce2());
+  set_session_key(nonce2());
 }
 
 void 
@@ -1440,7 +1451,7 @@
               nonce2(), hmac_key_encrypted);
   cmd.write_auth_cmd(role, pattern, client, nonce1, hmac_key_encrypted, signature);
   write_netcmd_and_try_flush(cmd);
-  session_key = netsync_session_key(nonce2());
+  set_session_key(nonce2());
 }
 
 void
@@ -2043,7 +2054,7 @@
   load_priv_key(app, app.signing_key, our_priv);
   string hmac_key;
   decrypt_rsa(app.lua, app.signing_key, our_priv, hmac_key_encrypted, hmac_key);
-  session_key = netsync_session_key(hmac_key);
+  set_session_key(hmac_key);
   queue_confirm_cmd();
 }
 
@@ -3182,7 +3193,7 @@
 {
   if (!armed)
     {
-      if (cmd.read(inbuf, session_key, read_hmac))
+      if (cmd.read(inbuf, read_hmac))
         {
 //          inbuf.erase(0, cmd.encoded_size());     
           armed = true;
--- transforms.hh
+++ transforms.hh
@@ -73,7 +73,12 @@
 void decode_gzip(gzip<T> const & in, T & out)
 { out = xform<CryptoPP::Gunzip>(in()); }
 
+// string variant for netsync
+template <typename T>
+void encode_gzip(std::string const & in, gzip<T> & out)
+{ out = xform<CryptoPP::Gzip>(in); }
 
+#endif
 // both at once (this is relatively common)
 
 template <typename T>