[8445] Fixed redundant calculation of v and s on every login Author: arrai

    The SRP-6 specifications clearly say, that v and s are only to be
    calculated on registering a user and changing his password; calculating
    them on every login is plain waste.

--HG--
branch : trunk

1 files changed, 24 insertions, 6 deletions

diff --git a/src/trinityrealm/AuthSocket.cpp b/src/trinityrealm/AuthSocket.cpp
index 14dadb1f2e2..88cd3aa0ec9 100644
--- a/src/trinityrealm/AuthSocket.cpp
+++ b/src/trinityrealm/AuthSocket.cpp
@@ -248,7 +248,6 @@ void AuthSocket::OnAccept()
     sLog.outBasic("Accepting connection from '%s:%d'",
         GetRemoteAddress().c_str(), GetRemotePort());
 
-    s.SetRand(s_BYTE_SIZE * 8);
 }
 
 /// Read the packet from the client
@@ -297,6 +296,8 @@ void AuthSocket::OnRead()
 /// Make the SRP6 calculation from hash in dB
 void AuthSocket::_SetVSFields(const std::string& rI)
 {
+    s.SetRand(s_BYTE_SIZE * 8);
+
     BigNumber I;
     I.SetHexStr(rI.c_str());
 
@@ -398,7 +399,7 @@ bool AuthSocket::_HandleLogonChallenge()
         ///- Get the account details from the account table
         // No SQL injection (escaped user name)
 
-        result = loginDatabase.PQuery("SELECT sha_pass_hash,id,locked,last_ip,gmlevel FROM account WHERE username = '%s'",_safelogin.c_str ());
+        result = loginDatabase.PQuery("SELECT sha_pass_hash,id,locked,last_ip,gmlevel,v,s FROM account WHERE username = '%s'",_safelogin.c_str ());
         if( result )
         {
             ///- If the IP is 'locked', check that the player comes indeed from the correct IP address
@@ -448,7 +449,21 @@ bool AuthSocket::_HandleLogonChallenge()
                 {
                     ///- Get the password from the account table, upper it, and make the SRP6 calculation
                     std::string rI = (*result)[0].GetCppString();
-                    _SetVSFields(rI);
+
+                    ///- Don't calculate (v, s) if there are already some in the database
+                    std::string databaseV = (*result)[5].GetCppString();
+                    std::string databaseS = (*result)[6].GetCppString();
+
+                    sLog.outDebug("database authentication values: v='%s' s='%s'", databaseV.c_str(), databaseS.c_str());
+
+                    // multiply with 2, bytes are stored as hexstring
+                    if(databaseV.size() != s_BYTE_SIZE*2 || databaseS.size() != s_BYTE_SIZE*2)
+                        _SetVSFields(rI);
+                    else
+                    {
+                        s.SetHexStr(databaseS.c_str());
+                        v.SetHexStr(databaseV.c_str());
+                    }
 
                     b.SetRand(19 * 8);
                     BigNumber gmod = g.ModExp(b, N);
@@ -593,8 +608,13 @@ bool AuthSocket::_HandleLogonProof()
 
     ///- Continue the SRP6 calculation based on data received from the client
     BigNumber A;
+
     A.SetBinary(lp.A, 32);
 
+    // SRP safeguard: abort if A==0
+    if (A.isZero())
+        return false;
+
     Sha1Hash sha;
     sha.UpdateBigNumbers(&A, &B, NULL);
     sha.Finalize();
@@ -605,7 +625,7 @@ bool AuthSocket::_HandleLogonProof()
     uint8 t[32];
     uint8 t1[16];
     uint8 vK[40];
-    memcpy(t, S.AsByteArray(), 32);
+    memcpy(t, S.AsByteArray(32), 32);
     for (int i = 0; i < 16; ++i)
     {
         t1[i] = t[i * 2];
@@ -906,8 +926,6 @@ bool AuthSocket::_HandleRealmList()
 
     SendBuf((char const*)hdr.contents(), hdr.size());
 
-    // Set check field before possible relogin to realm
-    _SetVSFields(rI);
     return true;
 }