Add option to not send pre v25 init packet

The legacy init packet (pre v25) sends information about the client's
password that a server could use to log in to other servers if the
username and password are the same. All the other benefits of SRP of
protocol v25 are missed if the legacy init packet is still sent during
connection creation.

This patch adds an option to not send the v25 init packet. Not sending
the v25 packet means breaking compat with pre v25 servers, but as the
option is not enabled by default, no servers are affected unless the
user explicitly flips the switch. More than 90% of the servers on the
serverlist support post v25 protocols.

The patch also fixes a bug with greying out of non compliant servers
being done wrongly, the min and max params were mixed.

1 files changed, 33 insertions, 21 deletions

diff --git a/src/client.cpp b/src/client.cpp
index 41468f0fd..2a8e02d6e 100644
--- a/src/client.cpp
+++ b/src/client.cpp
@@ -386,25 +386,30 @@ void Client::step(float dtime)
 			Player *myplayer = m_env.getLocalPlayer();
 			FATAL_ERROR_IF(myplayer == NULL, "Local player not found in environment.");
 
-			// Send TOSERVER_INIT_LEGACY
-			// [0] u16 TOSERVER_INIT_LEGACY
-			// [2] u8 SER_FMT_VER_HIGHEST_READ
-			// [3] u8[20] player_name
-			// [23] u8[28] password (new in some version)
-			// [51] u16 minimum supported network protocol version (added sometime)
-			// [53] u16 maximum supported network protocol version (added later than the previous one)
-
-			char pName[PLAYERNAME_SIZE];
-			char pPassword[PASSWORD_SIZE];
-			memset(pName, 0, PLAYERNAME_SIZE * sizeof(char));
-			memset(pPassword, 0, PASSWORD_SIZE * sizeof(char));
-
-			std::string hashed_password = translate_password(myplayer->getName(), m_password);
-			snprintf(pName, PLAYERNAME_SIZE, "%s", myplayer->getName());
-			snprintf(pPassword, PASSWORD_SIZE, "%s", hashed_password.c_str());
-
-			sendLegacyInit(pName, pPassword);
-			if (LATEST_PROTOCOL_VERSION >= 25)
+			u16 proto_version_min = g_settings->getFlag("send_pre_v25_init") ?
+				CLIENT_PROTOCOL_VERSION_MIN_LEGACY : CLIENT_PROTOCOL_VERSION_MIN;
+
+			if (proto_version_min < 25) {
+				// Send TOSERVER_INIT_LEGACY
+				// [0] u16 TOSERVER_INIT_LEGACY
+				// [2] u8 SER_FMT_VER_HIGHEST_READ
+				// [3] u8[20] player_name
+				// [23] u8[28] password (new in some version)
+				// [51] u16 minimum supported network protocol version (added sometime)
+				// [53] u16 maximum supported network protocol version (added later than the previous one)
+
+				char pName[PLAYERNAME_SIZE];
+				char pPassword[PASSWORD_SIZE];
+				memset(pName, 0, PLAYERNAME_SIZE * sizeof(char));
+				memset(pPassword, 0, PASSWORD_SIZE * sizeof(char));
+
+				std::string hashed_password = translate_password(myplayer->getName(), m_password);
+				snprintf(pName, PLAYERNAME_SIZE, "%s", myplayer->getName());
+				snprintf(pPassword, PASSWORD_SIZE, "%s", hashed_password.c_str());
+
+				sendLegacyInit(pName, pPassword);
+			}
+			if (CLIENT_PROTOCOL_VERSION_MAX >= 25)
 				sendInit(myplayer->getName());
 		}
 
@@ -1003,10 +1008,13 @@ void Client::sendLegacyInit(const char* playerName, const char* playerPassword)
 	NetworkPacket pkt(TOSERVER_INIT_LEGACY,
 			1 + PLAYERNAME_SIZE + PASSWORD_SIZE + 2 + 2);
 
+	u16 proto_version_min = g_settings->getFlag("send_pre_v25_init") ?
+		CLIENT_PROTOCOL_VERSION_MIN_LEGACY : CLIENT_PROTOCOL_VERSION_MIN;
+
 	pkt << (u8) SER_FMT_VER_HIGHEST_READ;
 	pkt.putRawString(playerName,PLAYERNAME_SIZE);
 	pkt.putRawString(playerPassword, PASSWORD_SIZE);
-	pkt << (u16) CLIENT_PROTOCOL_VERSION_MIN << (u16) CLIENT_PROTOCOL_VERSION_MAX;
+	pkt << (u16) proto_version_min << (u16) CLIENT_PROTOCOL_VERSION_MAX;
 
 	Send(&pkt);
 }
@@ -1017,8 +1025,12 @@ void Client::sendInit(const std::string &playerName)
 
 	// we don't support network compression yet
 	u16 supp_comp_modes = NETPROTO_COMPRESSION_NONE;
+
+	u16 proto_version_min = g_settings->getFlag("send_pre_v25_init") ?
+		CLIENT_PROTOCOL_VERSION_MIN_LEGACY : CLIENT_PROTOCOL_VERSION_MIN;
+
 	pkt << (u8) SER_FMT_VER_HIGHEST_READ << (u16) supp_comp_modes;
-	pkt << (u16) CLIENT_PROTOCOL_VERSION_MIN << (u16) CLIENT_PROTOCOL_VERSION_MAX;
+	pkt << (u16) proto_version_min << (u16) CLIENT_PROTOCOL_VERSION_MAX;
 	pkt << playerName;
 
 	Send(&pkt);