]> git.lizzy.rs Git - minetest.git/blobdiff - src/network/serverpackethandler.cpp
Optional reconnect functionality
[minetest.git] / src / network / serverpackethandler.cpp
index 6b1d5bc025aaa0bbb4d0bab53b5e3ea947b8f0e9..f756d80ef68fe29460c166cc04576bcc9f273b1a 100644 (file)
@@ -32,9 +32,11 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "version.h"
 #include "network/networkprotocol.h"
 #include "network/serveropcodes.h"
+#include "util/auth.h"
 #include "util/base64.h"
 #include "util/pointedthing.h"
 #include "util/serialize.h"
+#include "util/srp.h"
 
 void Server::handleCommand_Deprecated(NetworkPacket* pkt)
 {
@@ -89,21 +91,22 @@ void Server::handleCommand_Init(NetworkPacket* pkt)
        // First byte after command is maximum supported
        // serialization version
        u8 client_max;
-       u8 compression_modes;
+       u16 supp_compr_modes;
        u16 min_net_proto_version = 0;
        u16 max_net_proto_version;
+       std::string playerName;
 
-       *pkt >> client_max >> compression_modes >> min_net_proto_version
-                       >> max_net_proto_version;
+       *pkt >> client_max >> supp_compr_modes >> min_net_proto_version
+                       >> max_net_proto_version >> playerName;
 
        u8 our_max = SER_FMT_VER_HIGHEST_READ;
        // Use the highest version supported by both
-       int deployed = std::min(client_max, our_max);
+       u8 depl_serial_v = std::min(client_max, our_max);
        // If it's lower than the lowest supported, give up.
-       if (deployed < SER_FMT_VER_LOWEST)
-               deployed = SER_FMT_VER_INVALID;
+       if (depl_serial_v < SER_FMT_VER_LOWEST)
+               depl_serial_v = SER_FMT_VER_INVALID;
 
-       if (deployed == SER_FMT_VER_INVALID) {
+       if (depl_serial_v == SER_FMT_VER_INVALID) {
                actionstream << "Server: A mismatched client tried to connect from "
                                << addr_s << std::endl;
                infostream<<"Server: Cannot negotiate serialization version with "
@@ -112,7 +115,7 @@ void Server::handleCommand_Init(NetworkPacket* pkt)
                return;
        }
 
-       client->setPendingSerializationVersion(deployed);
+       client->setPendingSerializationVersion(depl_serial_v);
 
        /*
                Read and check network protocol version
@@ -137,7 +140,7 @@ void Server::handleCommand_Init(NetworkPacket* pkt)
 
        client->net_proto_version = net_proto_version;
 
-       // On this handler protocol version 25 is required
+       // On this handler at least protocol version 25 is required
        if (net_proto_version < 25 ||
                        net_proto_version < SERVER_PROTOCOL_VERSION_MIN ||
                        net_proto_version > SERVER_PROTOCOL_VERSION_MAX) {
@@ -156,41 +159,16 @@ void Server::handleCommand_Init(NetworkPacket* pkt)
                }
        }
 
-       // @TODO: check if we support same modes, but not required now
-
-       client->setSupportedCompressionModes(compression_modes);
-
-       m_clients.event(pkt->getPeerId(), CSE_Init);
-}
-
-void Server::handleCommand_Auth(NetworkPacket* pkt)
-{
-       std::string addr_s;
-       try {
-               Address address = getPeerAddress(pkt->getPeerId());
-               addr_s = address.serializeString();
-       }
-       catch (con::PeerNotFoundException &e) {
-               /*
-                * no peer for this packet found
-                * most common reason is peer timeout, e.g. peer didn't
-                * respond for some time, your server was overloaded or
-                * things like that.
-                */
-               infostream << "Server::ProcessData(): Canceling: peer "
-                               << pkt->getPeerId() << " not found" << std::endl;
-               return;
-       }
-
-       std::string playerName, playerPassword;
-
-       *pkt >> playerName >> playerPassword;
-
+       /*
+               Validate player name
+       */
        const char* playername = playerName.c_str();
 
-       if (playerName.size() > PLAYERNAME_SIZE) {
-               actionstream << "Server: Player with an too long name "
-                               << "tried to connect from " << addr_s << std::endl;
+       size_t pns = playerName.size();
+       if (pns == 0 || pns > PLAYERNAME_SIZE) {
+               actionstream << "Server: Player with "
+                       << ((pns > PLAYERNAME_SIZE) ? "a too long" : "an empty")
+                       << " name tried to connect from " << addr_s << std::endl;
                DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_WRONG_NAME);
                return;
        }
@@ -202,6 +180,11 @@ void Server::handleCommand_Auth(NetworkPacket* pkt)
                return;
        }
 
+       m_clients.setPlayerName(pkt->getPeerId(), playername);
+       //TODO (later) case insensitivity
+
+       std::string legacyPlayerNameCasing = playerName;
+
        if (!isSingleplayer() && strcasecmp(playername, "singleplayer") == 0) {
                actionstream << "Server: Player with the name \"singleplayer\" "
                                << "tried to connect from " << addr_s << std::endl;
@@ -211,7 +194,7 @@ void Server::handleCommand_Auth(NetworkPacket* pkt)
 
        {
                std::string reason;
-               if(m_script->on_prejoinplayer(playername, addr_s, reason)) {
+               if (m_script->on_prejoinplayer(playername, addr_s, &reason)) {
                        actionstream << "Server: Player with the name \"" << playerName << "\" "
                                        << "tried to connect from " << addr_s << " "
                                        << "but it was disallowed for the following reason: "
@@ -222,23 +205,9 @@ void Server::handleCommand_Auth(NetworkPacket* pkt)
                }
        }
 
-       if (playerPassword.size() > PASSWORD_SIZE) {
-               actionstream << "Server: Player with an too long password "
-                               << "tried to connect from " << addr_s << std::endl;
-               DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_WRONG_PASSWORD);
-               return;
-       }
-
        infostream << "Server: New connection: \"" << playerName << "\" from "
                        << addr_s << " (peer_id=" << pkt->getPeerId() << ")" << std::endl;
 
-       if(!base64_is_valid(playerPassword)){
-               actionstream << "Server: " << playerName
-                               << " supplied invalid password hash" << std::endl;
-               DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_WRONG_PASSWORD);
-               return;
-       }
-
        // Enforce user limit.
        // Don't enforce for users that have some admin right
        if (m_clients.getClientIDs(CS_Created).size() >= g_settings->getU16("max_users") &&
@@ -247,76 +216,78 @@ void Server::handleCommand_Auth(NetworkPacket* pkt)
                        !checkPriv(playername, "privs") &&
                        !checkPriv(playername, "password") &&
                        playername != g_settings->get("name")) {
-               actionstream << "Server: " << playername << " tried to join, but there"
-                               << " are already max_users="
+               actionstream << "Server: " << playername << " tried to join from "
+                               << addr_s << ", but there" << " are already max_users="
                                << g_settings->getU16("max_users") << " players." << std::endl;
                DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_TOO_MANY_USERS);
                return;
        }
 
-       std::string checkpwd; // Password hash to check against
-       bool has_auth = m_script->getAuth(playername, &checkpwd, NULL);
-
-       // If no authentication info exists for user, create it
-       if (!has_auth) {
-               if (!isSingleplayer() &&
-                               g_settings->getBool("disallow_empty_password") &&
-                               playerPassword.empty()) {
-                       actionstream << "Server: " << playerName
-                                       << " supplied empty password" << std::endl;
-                       DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_EMPTY_PASSWORD);
+       /*
+               Compose auth methods for answer
+       */
+       std::string encpwd; // encrypted Password field for the user
+       bool has_auth = m_script->getAuth(playername, &encpwd, NULL);
+       u32 auth_mechs = 0;
+
+       client->chosen_mech = AUTH_MECHANISM_NONE;
+
+       if (has_auth) {
+               std::vector<std::string> pwd_components = str_split(encpwd, '#');
+               if (pwd_components.size() == 4) {
+                       if (pwd_components[1] == "1") { // 1 means srp
+                               auth_mechs |= AUTH_MECHANISM_SRP;
+                               client->enc_pwd = encpwd;
+                       } else {
+                               actionstream << "User " << playername
+                                       << " tried to log in, but password field"
+                                       << " was invalid (unknown mechcode)." << std::endl;
+                               DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_SERVER_FAIL);
+                               return;
+                       }
+               } else if (base64_is_valid(encpwd)) {
+                       auth_mechs |= AUTH_MECHANISM_LEGACY_PASSWORD;
+                       client->enc_pwd = encpwd;
+               } else {
+                       actionstream << "User " << playername
+                               << " tried to log in, but password field"
+                               << " was invalid (invalid base64)." << std::endl;
+                       DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_SERVER_FAIL);
                        return;
                }
-               std::string raw_default_password =
-                       g_settings->get("default_password");
-               std::string initial_password =
-                       translatePassword(playername, raw_default_password);
-
-               // If default_password is empty, allow any initial password
-               if (raw_default_password.length() == 0)
-                       initial_password = playerPassword.c_str();
-
-               m_script->createAuth(playername, initial_password);
-       }
-
-       has_auth = m_script->getAuth(playername, &checkpwd, NULL);
-
-       if(!has_auth) {
-               actionstream << "Server: " << playerName << " cannot be authenticated"
-                               << " (auth handler does not work?)" << std::endl;
-               DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_SERVER_FAIL);
-               return;
-       }
-
-       if(playerPassword.c_str() != checkpwd) {
-               actionstream << "Server: " << playerName << " supplied wrong password"
-                               << std::endl;
-               DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_WRONG_PASSWORD);
-               return;
-       }
-
-       RemotePlayer *player =
-                       static_cast<RemotePlayer*>(m_env->getPlayer(playername));
-
-       if (player && player->peer_id != 0) {
-               errorstream << "Server: " << playername << ": Failed to emerge player"
-                               << " (player allocated to an another client)" << std::endl;
-               DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_ALREADY_CONNECTED);
+       } else {
+               std::string default_password = g_settings->get("default_password");
+               if (default_password.length() == 0) {
+                       auth_mechs |= AUTH_MECHANISM_FIRST_SRP;
+               } else {
+                       // Take care of default passwords.
+                       client->enc_pwd = getSRPVerifier(playerName, default_password);
+                       auth_mechs |= AUTH_MECHANISM_SRP;
+                       // Create auth, but only on successful login
+                       client->create_player_on_auth_success = true;
+               }
        }
 
-       m_clients.setPlayerName(pkt->getPeerId(), playername);
-
        /*
-               Answer with a TOCLIENT_INIT
+               Answer with a TOCLIENT_HELLO
        */
 
-       NetworkPacket resp_pkt(TOCLIENT_AUTH_ACCEPT, 1 + 6 + 8 + 4, pkt->getPeerId());
+       verbosestream << "Sending TOCLIENT_HELLO with auth method field: "
+               << auth_mechs << std::endl;
 
-       resp_pkt << v3f(0,0,0) << (u64) m_env->getServerMap().getSeed()
-                       << g_settings->getFloat("dedicated_server_step");
+       NetworkPacket resp_pkt(TOCLIENT_HELLO, 1 + 4
+               + legacyPlayerNameCasing.size(), pkt->getPeerId());
+
+       u16 depl_compress_mode = NETPROTO_COMPRESSION_NONE;
+       resp_pkt << depl_serial_v << depl_compress_mode << net_proto_version
+               << auth_mechs << legacyPlayerNameCasing;
 
        Send(&resp_pkt);
-       m_clients.event(pkt->getPeerId(), CSE_Init);
+
+       client->allowed_auth_mechs = auth_mechs;
+       client->setDeployedCompressionMode(depl_compress_mode);
+
+       m_clients.event(pkt->getPeerId(), CSE_Hello);
 }
 
 void Server::handleCommand_Init_Legacy(NetworkPacket* pkt)
@@ -354,7 +325,7 @@ void Server::handleCommand_Init_Legacy(NetworkPacket* pkt)
                return;
        }
 
-       verbosestream << "Server: Got TOSERVER_INIT from " << addr_s << " (peer_id="
+       verbosestream << "Server: Got TOSERVER_INIT_LEGACY from " << addr_s << " (peer_id="
                        << pkt->getPeerId() << ")" << std::endl;
 
        // Do not allow multiple players in simple singleplayer mode.
@@ -387,7 +358,7 @@ void Server::handleCommand_Init_Legacy(NetworkPacket* pkt)
                DenyAccess_Legacy(pkt->getPeerId(), std::wstring(
                                L"Your client's version is not supported.\n"
                                L"Server version is ")
-                               + narrow_to_wide(g_version_string) + L"."
+                               + utf8_to_wide(g_version_string) + L"."
                );
                return;
        }
@@ -422,6 +393,10 @@ void Server::handleCommand_Init_Legacy(NetworkPacket* pkt)
                        net_proto_version = max_net_proto_version;
        }
 
+       // The client will send up to date init packet, ignore this one
+       if (net_proto_version >= 25)
+               return;
+
        verbosestream << "Server: " << addr_s << ": Protocol version: min: "
                        << min_net_proto_version << ", max: " << max_net_proto_version
                        << ", chosen: " << net_proto_version << std::endl;
@@ -435,15 +410,15 @@ void Server::handleCommand_Init_Legacy(NetworkPacket* pkt)
                DenyAccess_Legacy(pkt->getPeerId(), std::wstring(
                                L"Your client's version is not supported.\n"
                                L"Server version is ")
-                               + narrow_to_wide(g_version_string) + L",\n"
+                               + utf8_to_wide(g_version_string) + L",\n"
                                + L"server's PROTOCOL_VERSION is "
-                               + narrow_to_wide(itos(SERVER_PROTOCOL_VERSION_MIN))
+                               + utf8_to_wide(itos(SERVER_PROTOCOL_VERSION_MIN))
                                + L"..."
-                               + narrow_to_wide(itos(SERVER_PROTOCOL_VERSION_MAX))
+                               + utf8_to_wide(itos(SERVER_PROTOCOL_VERSION_MAX))
                                + L", client's PROTOCOL_VERSION is "
-                               + narrow_to_wide(itos(min_net_proto_version))
+                               + utf8_to_wide(itos(min_net_proto_version))
                                + L"..."
-                               + narrow_to_wide(itos(max_net_proto_version))
+                               + utf8_to_wide(itos(max_net_proto_version))
                );
                return;
        }
@@ -455,13 +430,13 @@ void Server::handleCommand_Init_Legacy(NetworkPacket* pkt)
                        DenyAccess_Legacy(pkt->getPeerId(), std::wstring(
                                        L"Your client's version is not supported.\n"
                                        L"Server version is ")
-                                       + narrow_to_wide(g_version_string) + L",\n"
+                                       + utf8_to_wide(g_version_string) + L",\n"
                                        + L"server's PROTOCOL_VERSION (strict) is "
-                                       + narrow_to_wide(itos(LATEST_PROTOCOL_VERSION))
+                                       + utf8_to_wide(itos(LATEST_PROTOCOL_VERSION))
                                        + L", client's PROTOCOL_VERSION is "
-                                       + narrow_to_wide(itos(min_net_proto_version))
+                                       + utf8_to_wide(itos(min_net_proto_version))
                                        + L"..."
-                                       + narrow_to_wide(itos(max_net_proto_version))
+                                       + utf8_to_wide(itos(max_net_proto_version))
                        );
                        return;
                }
@@ -509,12 +484,12 @@ void Server::handleCommand_Init_Legacy(NetworkPacket* pkt)
 
        {
                std::string reason;
-               if (m_script->on_prejoinplayer(playername, addr_s, reason)) {
+               if (m_script->on_prejoinplayer(playername, addr_s, &reason)) {
                        actionstream << "Server: Player with the name \"" << playername << "\" "
                                        << "tried to connect from " << addr_s << " "
                                        << "but it was disallowed for the following reason: "
                                        << reason << std::endl;
-                       DenyAccess_Legacy(pkt->getPeerId(), narrow_to_wide(reason.c_str()));
+                       DenyAccess_Legacy(pkt->getPeerId(), utf8_to_wide(reason.c_str()));
                        return;
                }
        }
@@ -603,7 +578,7 @@ void Server::handleCommand_Init_Legacy(NetworkPacket* pkt)
                        static_cast<RemotePlayer*>(m_env->getPlayer(playername));
 
        if (player && player->peer_id != 0) {
-               errorstream << "Server: " << playername << ": Failed to emerge player"
+               actionstream << "Server: " << playername << ": Failed to emerge player"
                                << " (player allocated to an another client)" << std::endl;
                DenyAccess_Legacy(pkt->getPeerId(), L"Another client is connected with this "
                                L"name. If your client closed unexpectedly, try again in "
@@ -624,7 +599,7 @@ void Server::handleCommand_Init_Legacy(NetworkPacket* pkt)
                        << g_settings->getFloat("dedicated_server_step");
 
        Send(&resp_pkt);
-       m_clients.event(pkt->getPeerId(), CSE_Init);
+       m_clients.event(pkt->getPeerId(), CSE_InitLegacy);
 }
 
 void Server::handleCommand_Init2(NetworkPacket* pkt)
@@ -642,7 +617,7 @@ void Server::handleCommand_Init2(NetworkPacket* pkt)
                playersao = StageTwoClientInit(pkt->getPeerId());
 
                if (playersao == NULL) {
-                       errorstream
+                       actionstream
                                << "TOSERVER_INIT2 stage 2 client init failed for peer "
                                << pkt->getPeerId() << std::endl;
                        return;
@@ -739,7 +714,7 @@ void Server::handleCommand_ClientReady(NetworkPacket* pkt)
        PlayerSAO* playersao = StageTwoClientInit(peer_id);
 
        if (playersao == NULL) {
-               errorstream
+               actionstream
                        << "TOSERVER_CLIENT_READY stage 2 client init failed for peer_id: "
                        << peer_id << std::endl;
                m_con.DisconnectPeer(peer_id);
@@ -1178,7 +1153,7 @@ void Server::handleCommand_Damage(NetworkPacket* pkt)
                                << std::endl;
 
                playersao->setHP(playersao->getHP() - damage);
-               SendPlayerHPOrDie(playersao->getPeerID(), playersao->getHP() == 0);
+               SendPlayerHPOrDie(playersao);
        }
 }
 
@@ -1223,33 +1198,33 @@ void Server::handleCommand_Breath(NetworkPacket* pkt)
 
 void Server::handleCommand_Password(NetworkPacket* pkt)
 {
-       if ((pkt->getCommand() == TOSERVER_PASSWORD && pkt->getSize() < 4) ||
-                       pkt->getSize() != PASSWORD_SIZE * 2)
+       if (pkt->getSize() != PASSWORD_SIZE * 2)
                return;
 
        std::string oldpwd;
        std::string newpwd;
 
-       if (pkt->getCommand() == TOSERVER_PASSWORD) {
-               *pkt >> oldpwd >> newpwd;
+       // Deny for clients using the new protocol
+       RemoteClient* client = getClient(pkt->getPeerId(), CS_Created);
+       if (client->net_proto_version >= 25) {
+               infostream << "Server::handleCommand_Password(): Denying change: "
+                       << " Client protocol version for peer_id=" << pkt->getPeerId()
+                       << " too new!" << std::endl;
+               return;
        }
-       // 13/03/15
-       // Protocol v24 compat. Please remove in 1 year after
-       // client convergence to 0.4.13/0.5.x
-       else {
-               for (u16 i = 0; i < PASSWORD_SIZE - 1; i++) {
-                       char c = pkt->getChar(i);
-                       if (c == 0)
-                               break;
-                       oldpwd += c;
-               }
 
-               for (u16 i = 0; i < PASSWORD_SIZE - 1; i++) {
-                       char c = pkt->getChar(PASSWORD_SIZE + i);
-                       if (c == 0)
-                               break;
-                       newpwd += c;
-               }
+       for (u16 i = 0; i < PASSWORD_SIZE - 1; i++) {
+               char c = pkt->getChar(i);
+               if (c == 0)
+                       break;
+               oldpwd += c;
+       }
+
+       for (u16 i = 0; i < PASSWORD_SIZE - 1; i++) {
+               char c = pkt->getChar(PASSWORD_SIZE + i);
+               if (c == 0)
+                       break;
+               newpwd += c;
        }
 
        Player *player = m_env->getPlayer(pkt->getPeerId());
@@ -1537,14 +1512,12 @@ void Server::handleCommand_Interact(NetworkPacket* pkt)
                        // If the object is a player and its HP changed
                        if (src_original_hp != pointed_object->getHP() &&
                                        pointed_object->getType() == ACTIVEOBJECT_TYPE_PLAYER) {
-                               SendPlayerHPOrDie(((PlayerSAO*)pointed_object)->getPeerID(),
-                                               pointed_object->getHP() == 0);
+                               SendPlayerHPOrDie((PlayerSAO *)pointed_object);
                        }
 
                        // If the puncher is a player and its HP changed
-                       if (dst_origin_hp != playersao->getHP()) {
-                               SendPlayerHPOrDie(playersao->getPeerID(), playersao->getHP() == 0);
-                       }
+                       if (dst_origin_hp != playersao->getHP())
+                               SendPlayerHPOrDie(playersao);
                }
 
        } // action == 0
@@ -1771,7 +1744,7 @@ void Server::handleCommand_NodeMetaFields(NetworkPacket* pkt)
 
        *pkt >> p >> formname >> num;
 
-       std::map<std::string, std::string> fields;
+       StringMap fields;
        for (u16 k = 0; k < num; k++) {
                std::string fieldname;
                *pkt >> fieldname;
@@ -1821,7 +1794,7 @@ void Server::handleCommand_InventoryFields(NetworkPacket* pkt)
 
        *pkt >> formname >> num;
 
-       std::map<std::string, std::string> fields;
+       StringMap fields;
        for (u16 k = 0; k < num; k++) {
                std::string fieldname;
                *pkt >> fieldname;
@@ -1848,3 +1821,266 @@ void Server::handleCommand_InventoryFields(NetworkPacket* pkt)
 
        m_script->on_playerReceiveFields(playersao, formname, fields);
 }
+
+void Server::handleCommand_FirstSrp(NetworkPacket* pkt)
+{
+       RemoteClient* client = getClient(pkt->getPeerId(), CS_Invalid);
+       ClientState cstate = client->getState();
+
+       std::string playername = client->getName();
+
+       std::string salt;
+       std::string verification_key;
+
+       std::string addr_s = getPeerAddress(pkt->getPeerId()).serializeString();
+       u8 is_empty;
+
+       *pkt >> salt >> verification_key >> is_empty;
+
+       verbosestream << "Server: Got TOSERVER_FIRST_SRP from " << addr_s
+               << ", with is_empty= " << is_empty << std::endl;
+
+       // Either this packet is sent because the user is new or to change the password
+       if (cstate == CS_HelloSent) {
+               if (!client->isMechAllowed(AUTH_MECHANISM_FIRST_SRP)) {
+                       actionstream << "Server: Client from " << addr_s
+                                       << " tried to set password without being "
+                                       << "authenticated, or the username being new." << std::endl;
+                       DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_UNEXPECTED_DATA);
+                       return;
+               }
+
+               if (!isSingleplayer() &&
+                               g_settings->getBool("disallow_empty_password") &&
+                               is_empty == 1) {
+                       actionstream << "Server: " << playername
+                                       << " supplied empty password from " << addr_s << std::endl;
+                       DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_EMPTY_PASSWORD);
+                       return;
+               }
+
+               std::string initial_ver_key;
+
+               initial_ver_key = encodeSRPVerifier(verification_key, salt);
+               m_script->createAuth(playername, initial_ver_key);
+
+               acceptAuth(pkt->getPeerId(), false);
+       } else {
+               if (cstate < CS_SudoMode) {
+                       infostream << "Server::ProcessData(): Ignoring TOSERVER_FIRST_SRP from "
+                                       << addr_s << ": " << "Client has wrong state " << cstate << "."
+                                       << std::endl;
+                       return;
+               }
+               m_clients.event(pkt->getPeerId(), CSE_SudoLeave);
+               std::string pw_db_field = encodeSRPVerifier(verification_key, salt);
+               bool success = m_script->setPassword(playername, pw_db_field);
+               if (success) {
+                       actionstream << playername << " changes password" << std::endl;
+                       SendChatMessage(pkt->getPeerId(), L"Password change successful.");
+               } else {
+                       actionstream << playername << " tries to change password but "
+                               << "it fails" << std::endl;
+                       SendChatMessage(pkt->getPeerId(), L"Password change failed or unavailable.");
+               }
+       }
+}
+
+void Server::handleCommand_SrpBytesA(NetworkPacket* pkt)
+{
+       RemoteClient* client = getClient(pkt->getPeerId(), CS_Invalid);
+       ClientState cstate = client->getState();
+
+       bool wantSudo = (cstate == CS_Active);
+
+       if (!((cstate == CS_HelloSent) || (cstate == CS_Active))) {
+               actionstream << "Server: got SRP _A packet in wrong state "
+                       << cstate << " from "
+                       << getPeerAddress(pkt->getPeerId()).serializeString()
+                       << ". Ignoring." << std::endl;
+               return;
+       }
+
+       if (client->chosen_mech != AUTH_MECHANISM_NONE) {
+               actionstream << "Server: got SRP _A packet, while auth"
+                       << "is already going on with mech " << client->chosen_mech
+                       << " from " << getPeerAddress(pkt->getPeerId()).serializeString()
+                       << " (wantSudo=" << wantSudo << "). Ignoring." << std::endl;
+               if (wantSudo) {
+                       DenySudoAccess(pkt->getPeerId());
+                       return;
+               } else {
+                       DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_UNEXPECTED_DATA);
+                       return;
+               }
+       }
+
+       std::string bytes_A;
+       u8 based_on;
+       *pkt >> bytes_A >> based_on;
+
+       infostream << "Server: TOSERVER_SRP_BYTES_A received with "
+               << "based_on=" << int(based_on) << " and len_A="
+               << bytes_A.length() << "." << std::endl;
+
+       AuthMechanism chosen = (based_on == 0) ?
+               AUTH_MECHANISM_LEGACY_PASSWORD : AUTH_MECHANISM_SRP;
+
+       if (wantSudo) {
+               if (!client->isSudoMechAllowed(chosen)) {
+                       actionstream << "Server: Player \"" << client->getName()
+                               << "\" at " << getPeerAddress(pkt->getPeerId()).serializeString()
+                               << " tried to change password using unallowed mech "
+                               << chosen << "." << std::endl;
+                       DenySudoAccess(pkt->getPeerId());
+                       return;
+               }
+       } else {
+               if (!client->isMechAllowed(chosen)) {
+                       actionstream << "Server: Client tried to authenticate from "
+                               << getPeerAddress(pkt->getPeerId()).serializeString()
+                               << " using unallowed mech " << chosen << "." << std::endl;
+                       DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_UNEXPECTED_DATA);
+                       return;
+               }
+       }
+
+       client->chosen_mech = chosen;
+
+       std::string bytes_s;
+       std::string bytes_v;
+
+       if (based_on == 0) {
+               char *p_bytes_s = 0;
+               size_t len_s = 0;
+               char *p_bytes_v = 0;
+               size_t len_v = 0;
+               getSRPVerifier(client->getName(), client->enc_pwd,
+                       &p_bytes_s, &len_s,
+                       &p_bytes_v, &len_v);
+               bytes_s = std::string(p_bytes_s, len_s);
+               bytes_v = std::string(p_bytes_v, len_v);
+               free(p_bytes_s);
+               free(p_bytes_v);
+       } else if (!decodeSRPVerifier(client->enc_pwd, &bytes_s, &bytes_v)) {
+               // Non-base64 errors should have been catched in the init handler
+               actionstream << "Server: User " << client->getName()
+                       << " tried to log in, but srp verifier field"
+                       << " was invalid (most likely invalid base64)." << std::endl;
+               DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_SERVER_FAIL);
+               return;
+       }
+
+       char *bytes_B = 0;
+       size_t len_B = 0;
+
+       client->auth_data = srp_verifier_new(SRP_SHA256, SRP_NG_2048,
+               client->getName().c_str(),
+               (const unsigned char *) bytes_s.c_str(), bytes_s.size(),
+               (const unsigned char *) bytes_v.c_str(), bytes_v.size(),
+               (const unsigned char *) bytes_A.c_str(), bytes_A.size(),
+               NULL, 0,
+               (unsigned char **) &bytes_B, &len_B, NULL, NULL);
+
+       if (!bytes_B) {
+               actionstream << "Server: User " << client->getName()
+                       << " tried to log in, SRP-6a safety check violated in _A handler."
+                       << std::endl;
+               if (wantSudo) {
+                       DenySudoAccess(pkt->getPeerId());
+                       return;
+               } else {
+                       DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_UNEXPECTED_DATA);
+                       return;
+               }
+       }
+
+       NetworkPacket resp_pkt(TOCLIENT_SRP_BYTES_S_B, 0, pkt->getPeerId());
+       resp_pkt << bytes_s << std::string(bytes_B, len_B);
+       Send(&resp_pkt);
+}
+
+void Server::handleCommand_SrpBytesM(NetworkPacket* pkt)
+{
+       RemoteClient* client = getClient(pkt->getPeerId(), CS_Invalid);
+       ClientState cstate = client->getState();
+
+       bool wantSudo = (cstate == CS_Active);
+
+       verbosestream << "Server: Recieved TOCLIENT_SRP_BYTES_M." << std::endl;
+
+       if (!((cstate == CS_HelloSent) || (cstate == CS_Active))) {
+               actionstream << "Server: got SRP _M packet in wrong state "
+                       << cstate << " from "
+                       << getPeerAddress(pkt->getPeerId()).serializeString()
+                       << ". Ignoring." << std::endl;
+               return;
+       }
+
+       if ((client->chosen_mech != AUTH_MECHANISM_SRP)
+               && (client->chosen_mech != AUTH_MECHANISM_LEGACY_PASSWORD)) {
+               actionstream << "Server: got SRP _M packet, while auth"
+                       << "is going on with mech " << client->chosen_mech
+                       << " from " << getPeerAddress(pkt->getPeerId()).serializeString()
+                       << " (wantSudo=" << wantSudo << "). Denying." << std::endl;
+               if (wantSudo) {
+                       DenySudoAccess(pkt->getPeerId());
+                       return;
+               } else {
+                       DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_UNEXPECTED_DATA);
+                       return;
+               }
+       }
+
+       std::string bytes_M;
+       *pkt >> bytes_M;
+
+       if (srp_verifier_get_session_key_length((SRPVerifier *) client->auth_data)
+                       != bytes_M.size()) {
+               actionstream << "Server: User " << client->getName()
+                       << " at " << getPeerAddress(pkt->getPeerId()).serializeString()
+                       << " sent bytes_M with invalid length " << bytes_M.size() << std::endl;
+               DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_UNEXPECTED_DATA);
+               return;
+       }
+
+       unsigned char *bytes_HAMK = 0;
+
+       srp_verifier_verify_session((SRPVerifier *) client->auth_data,
+               (unsigned char *)bytes_M.c_str(), &bytes_HAMK);
+
+       if (!bytes_HAMK) {
+               if (wantSudo) {
+                       actionstream << "Server: User " << client->getName()
+                               << " at " << getPeerAddress(pkt->getPeerId()).serializeString()
+                               << " tried to change their password, but supplied wrong"
+                               << " (SRP) password for authentication." << std::endl;
+                       DenySudoAccess(pkt->getPeerId());
+                       return;
+               } else {
+                       actionstream << "Server: User " << client->getName()
+                               << " at " << getPeerAddress(pkt->getPeerId()).serializeString()
+                               << " supplied wrong (SRP) password from address "
+                               << getPeerAddress(pkt->getPeerId()).serializeString()
+                               << "." << std::endl;
+                       DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_WRONG_PASSWORD);
+                       return;
+               }
+       }
+
+       if (client->create_player_on_auth_success) {
+               std::string playername = client->getName();
+               m_script->createAuth(playername, client->enc_pwd);
+
+               std::string checkpwd; // not used, but needed for passing something
+               if (!m_script->getAuth(playername, &checkpwd, NULL)) {
+                       actionstream << "Server: " << playername << " cannot be authenticated"
+                               << " (auth handler does not work?)" << std::endl;
+                       DenyAccess(pkt->getPeerId(), SERVER_ACCESSDENIED_SERVER_FAIL);
+                       return;
+               }
+               client->create_player_on_auth_success = false;
+       }
+
+       acceptAuth(pkt->getPeerId(), wantSudo);
+}