login with random hash

The account server sends out a random number, which is
additionally used for hashing the password.

Reviewed by Bertram

2 files changed, 64 insertions, 3 deletions

diff --git a/src/account-server/account.h b/src/account-server/account.h
index 189e3b5..98794fb 100644
--- a/src/account-server/account.h
+++ b/src/account-server/account.h
@@ -78,6 +78,24 @@ class Account
         const std::string &getPassword() const
         { return mPassword; }
 
+        /**
+         * Set the random salt. This salt is sent to the client, so the client
+         * can hash its password with this random salt.
+         * This will help to protect against replay attacks.
+         *
+         * @param the new random salt to be sent out next login
+         */
+        void setRandomSalt(const std::string &salt)
+        { mRandomSalt = salt; }
+
+
+        /**
+         * Get the user random salt.
+         *
+         * @return the random salt used for next login.
+         */
+        const std::string &getRandomSalt() const
+        { return mRandomSalt; }
 
         /**
          * Set the user email address. The email address is expected to be
@@ -204,6 +222,8 @@ class Account
 
         std::string mName;        /**< User name */
         std::string mPassword;    /**< User password (hashed with salt) */
+        std::string mRandomSalt;  /**< A random sequence sent to client to
+                                       protect against replay attacks.*/
         std::string mEmail;       /**< User email address (hashed) */
         Characters mCharacters;   /**< Character data */
         int mID;                  /**< Unique id */
diff --git a/src/account-server/accounthandler.cpp b/src/account-server/accounthandler.cpp
index 7bd2a0a..f577908 100644
--- a/src/account-server/accounthandler.cpp
+++ b/src/account-server/accounthandler.cpp
@@ -89,6 +89,7 @@ protected:
     void computerDisconnected(NetComputer *comp);
 
 private:
+    void handleLoginRandTriggerMessage(AccountClient &client, MessageIn &msg);
     void handleLoginMessage(AccountClient &client, MessageIn &msg);
     void handleLogoutMessage(AccountClient &client);
     void handleReconnectMessage(AccountClient &client, MessageIn &msg);
@@ -103,6 +104,10 @@ private:
 
     void addServerInfo(MessageOut *msg);
 
+    /** List of all accounts which requested a random seed, but are not logged
+     *  yet. This list will be regularly remove (after timeout) old accounts
+     */
+    std::list<Account*> mPendingAccounts;
 
     /** List of attributes that the client can send at account creation. */
     std::vector<int> mModifiableAttributes;
@@ -292,6 +297,32 @@ void AccountHandler::sendCharacterData(AccountClient &client,
     client.send(charInfo);
 }
 
+std::string getRandomString(int length)
+{
+    char s[length];
+    // No need to care about zeros. They can be handled.
+    // But care for endianness
+    for (int i = 0; i < length; ++i)
+        s[i] = (char)rand();
+
+    return std::string(s, length);
+}
+
+void AccountHandler::handleLoginRandTriggerMessage(AccountClient &client, MessageIn &msg)
+{
+    std::string salt = getRandomString(4);
+    std::string username = msg.readString();
+
+    if (Account *acc = storage->getAccount(username))
+    {
+        acc->setRandomSalt(salt);
+        mPendingAccounts.push_back(acc);
+    }
+    MessageOut reply(APMSG_LOGIN_RNDTRGR_RESPONSE);
+    reply.writeString(salt);
+    client.send(reply);
+}
+
 void AccountHandler::handleLoginMessage(AccountClient &client, MessageIn &msg)
 {
     MessageOut reply(APMSG_LOGIN_RESPONSE);
@@ -349,9 +380,14 @@ void AccountHandler::handleLoginMessage(AccountClient &client, MessageIn &msg)
     }
 
     // Check if the account exists
-    Account *acc = storage->getAccount(username);
-
-    if (!acc || acc->getPassword() != sha256(password))
+    Account *acc = 0;
+    std::list<Account*>::iterator ita;
+    for ( ita = mPendingAccounts.begin() ; ita != mPendingAccounts.end(); ita++ )
+        if ((*ita)->getName() == username)
+            acc = *ita;
+    mPendingAccounts.remove(acc);
+
+    if (!acc || sha256(acc->getPassword() + acc->getRandomSalt()) != password)
     {
         reply.writeInt8(ERRMSG_INVALID_ARGUMENT);
         client.send(reply);
@@ -978,6 +1014,11 @@ void AccountHandler::processMessage(NetComputer *comp, MessageIn &message)
 
     switch (message.getId())
     {
+        case PAMSG_LOGIN_RNDTRGR:
+            LOG_DEBUG("Received msg ... PAMSG_LOGIN_RANDTRIGGER");
+            handleLoginRandTriggerMessage(client, message);
+            break;
+
         case PAMSG_LOGIN:
             LOG_DEBUG("Received msg ... PAMSG_LOGIN");
             handleLoginMessage(client, message);