Avoid undefined behaviour const_casting std::string c_str()

Use non-const data() instead

See: #224

src/network/core/packet.cpp

@@ -11,6 +11,7 @@
 
 #include "../../stdafx.h"
 #include "../../string_func.h"
+#include "../../string_func_extra.h"
 #include "../../command_type.h"
 
 #include "packet.h"
@@ -337,7 +338,7 @@ void Packet::Recv_string(std::string &buffer, StringValidationSettings settings)
 	size_t length = ttd_strnlen((const char *)(this->buffer + this->pos), this->size - this->pos - 1);
 	buffer.assign((const char *)(this->buffer + this->pos), length);
 	this->pos += length + 1;
-	str_validate(const_cast<char *>(buffer.c_str()), buffer.c_str() + buffer.size(), settings);
+	str_validate_inplace(buffer, settings);
 }
 
 /**

src/network/network.cpp

@@ -946,7 +946,7 @@ void NetworkGameLoop()
 				cp->text.resize(MAX_CMD_TEXT_LENGTH);
 				static_assert(MAX_CMD_TEXT_LENGTH > 8192);
 				int ret = sscanf(p, "date{%x; %x; %x}; company: %x; tile: %x (%*u x %*u); p1: %x; p2: %x; p3: " OTTD_PRINTFHEX64 "; cmd: %x; \"%8192[^\"]\"",
-						&next_date, &next_date_fract, &next_tick_skip_counter, &company, &cp->tile, &cp->p1, &cp->p2, &cp->p3, &cp->cmd, const_cast<char *>(cp->text.c_str()));
+						&next_date, &next_date_fract, &next_tick_skip_counter, &company, &cp->tile, &cp->p1, &cp->p2, &cp->p3, &cp->cmd, cp->text.data());
 				/* There are 10 pieces of data to read, however the last is a
 				 * string that might or might not exist. Ignore it if that
 				 * string misses because in 99% of the time it's not used. */

src/network/network_client.cpp

@@ -1163,7 +1163,7 @@ NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_DESYNC_LOG(Pack
 {
 	uint size = p->Recv_uint16();
 	this->server_desync_log.resize(this->server_desync_log.size() + size);
-	p->Recv_binary(const_cast<char *>(this->server_desync_log.data() + this->server_desync_log.size() - size), size);
+	p->Recv_binary(this->server_desync_log.data() + this->server_desync_log.size() - size, size);
 	DEBUG(net, 2, "Received %u bytes of server desync log", size);
 	return NETWORK_RECV_STATUS_OKAY;
 }

src/network/network_server.cpp

@@ -1280,7 +1280,7 @@ NetworkRecvStatus ServerNetworkGameSocketHandler::Receive_CLIENT_DESYNC_LOG(Pack
 {
 	uint size = p->Recv_uint16();
 	this->desync_log.resize(this->desync_log.size() + size);
-	p->Recv_binary(const_cast<char *>(this->desync_log.data() + this->desync_log.size() - size), size);
+	p->Recv_binary(this->desync_log.data() + this->desync_log.size() - size, size);
 	DEBUG(net, 2, "Received %u bytes of client desync log", size);
 	this->receive_limit += p->size;
 	return NETWORK_RECV_STATUS_OKAY;