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authorRubidium <rubidium@openttd.org>2021-04-18 09:01:27 +0200
committerrubidium42 <rubidium42@users.noreply.github.com>2021-04-24 20:42:01 +0200
commitc545cc9d7039a89e23de160b1c93adc959eabda5 (patch)
tree8522a8e09c0b9fa7e3eba8b4becaef15080f5605
parent470d8b66372ceb5a38ce9823d451bddd2f3eca35 (diff)
downloadopenttd-c545cc9d7039a89e23de160b1c93adc959eabda5.tar.xz
Codechange: move more logic about packet size validity and reading into Packet
-rw-r--r--src/network/core/packet.cpp23
-rw-r--r--src/network/core/packet.h3
-rw-r--r--src/network/core/tcp.cpp10
-rw-r--r--src/network/core/udp.cpp4
4 files changed, 28 insertions, 12 deletions
diff --git a/src/network/core/packet.cpp b/src/network/core/packet.cpp
index 94ffcc558..4eb0e929e 100644
--- a/src/network/core/packet.cpp
+++ b/src/network/core/packet.cpp
@@ -181,13 +181,32 @@ bool Packet::CanReadFromPacket(uint bytes_to_read)
}
/**
+ * Check whether the packet, given the position of the "write" pointer, has read
+ * enough of the packet to contain its size.
+ * @return True iff there is enough data in the packet to contain the packet's size.
+ */
+bool Packet::HasPacketSizeData() const
+{
+ return this->pos >= sizeof(PacketSize);
+}
+
+/**
* Reads the packet size from the raw packet and stores it in the packet->size
+ * @return True iff the packet size seems plausible.
*/
-void Packet::ReadRawPacketSize()
+bool Packet::ParsePacketSize()
{
assert(this->cs != nullptr && this->next == nullptr);
this->size = (PacketSize)this->buffer[0];
this->size += (PacketSize)this->buffer[1] << 8;
+
+ /* If the size of the packet is less than the bytes required for the size and type of
+ * the packet, or more than the allowed limit, then something is wrong with the packet.
+ * In those cases the packet can generally be regarded as containing garbage data. */
+ if (this->size < sizeof(PacketSize) + sizeof(PacketType) || this->size > SEND_MTU) return false;
+
+ this->pos = sizeof(PacketSize);
+ return true;
}
/**
@@ -195,8 +214,6 @@ void Packet::ReadRawPacketSize()
*/
void Packet::PrepareToRead()
{
- this->ReadRawPacketSize();
-
/* Put the position on the right place */
this->pos = sizeof(PacketSize);
}
diff --git a/src/network/core/packet.h b/src/network/core/packet.h
index c9be4eeb5..6e5c5509c 100644
--- a/src/network/core/packet.h
+++ b/src/network/core/packet.h
@@ -71,7 +71,8 @@ public:
void Send_string(const char *data);
/* Reading/receiving of packets */
- void ReadRawPacketSize();
+ bool HasPacketSizeData() const;
+ bool ParsePacketSize();
void PrepareToRead();
bool CanReadFromPacket (uint bytes_to_read);
diff --git a/src/network/core/tcp.cpp b/src/network/core/tcp.cpp
index a51913d84..1461a9298 100644
--- a/src/network/core/tcp.cpp
+++ b/src/network/core/tcp.cpp
@@ -155,8 +155,8 @@ Packet *NetworkTCPSocketHandler::ReceivePacket()
Packet *p = this->packet_recv;
/* Read packet size */
- if (p->pos < sizeof(PacketSize)) {
- while (p->pos < sizeof(PacketSize)) {
+ if (!p->HasPacketSizeData()) {
+ while (!p->HasPacketSizeData()) {
/* Read the size of the packet */
res = recv(this->sock, (char*)p->buffer + p->pos, sizeof(PacketSize) - p->pos, 0);
if (res == -1) {
@@ -178,10 +178,8 @@ Packet *NetworkTCPSocketHandler::ReceivePacket()
p->pos += res;
}
- /* Read the packet size from the received packet */
- p->ReadRawPacketSize();
-
- if (p->size > SEND_MTU) {
+ /* Parse the size in the received packet and if not valid, close the connection. */
+ if (!p->ParsePacketSize()) {
this->CloseConnection();
return nullptr;
}
diff --git a/src/network/core/udp.cpp b/src/network/core/udp.cpp
index 72fec49e1..614ae8c3b 100644
--- a/src/network/core/udp.cpp
+++ b/src/network/core/udp.cpp
@@ -134,14 +134,14 @@ void NetworkUDPSocketHandler::ReceivePackets()
#endif
NetworkAddress address(client_addr, client_len);
- p.PrepareToRead();
/* If the size does not match the packet must be corrupted.
* Otherwise it will be marked as corrupted later on. */
- if (nbytes != p.size) {
+ if (!p.ParsePacketSize() || nbytes != p.size) {
DEBUG(net, 1, "received a packet with mismatching size from %s", address.GetAddressAsString().c_str());
continue;
}
+ p.PrepareToRead();
/* Handle the packet */
this->HandleUDPPacket(&p, &address);