Code Snippet
class PortForward {
public:
// COM interfaces
IUPnPNAT *Nat;
IStaticPortMappingCollection *Collection;
IStaticPortMapping *Mapping;
// Methods
PortForward();
~PortForward();
bool SetupForward(char protocol, int externalport, int internalport, read ipaddress, read name);
bool Access();
bool Add(char protocol, int externalport, int internalport, read ipaddress, read name);
};
PortForward::PortForward() {
// Set the COM interface pointers to NULL so we'll know if we've initialized them
Nat = NULL;
Collection = NULL;
Mapping = NULL;
}
// Delete this PortForward object
PortForward::~PortForward() {
// Release the COM interfaces that we got access to
if (Mapping) { Mapping->Release(); Mapping = NULL; }
if (Collection) { Collection->Release(); Collection = NULL; }
if (Nat) { Nat->Release(); Nat = NULL; }
}
// Takes a protocol 't' for TCP or 'u' for UDP, the port to forward externally and internally, and a program name up to 11 letters a-z and A-Z only
bool PortForward::SetupForward(char protocol, int externalport, int internalport, read ipaddress, read name) {
// Connect to the COM object, and have it begin talking UPnP to the router
if (!Access()) return false;
// Remove any forward the router has for the given protocol and port
Remove(protocol, externalport); // Even if remove fails, we still want to try to add
// Add a fresh port mapping with the right name and a checked box
if (!Add(protocol, externalport, internalport, ipaddress, name)) return false;
// Everything worked
return true;
}
// Get access to the COM objects
// Returns true if it works, false if there was an error
bool PortForward::Access() {
// Initialize COM itself so this thread can use it
HRESULT result = CoInitialize(NULL); // Must be NULL
if (FAILED(result)) Report("PortForward::Access CoInitialize failed");
if (FAILED(result)) return false;
// Access the IUPnPNAT COM interface, has Windows send UPnP messages to the NAT router
result = CoCreateInstance(__uuidof(UPnPNAT), NULL, CLSCTX_ALL, __uuidof(IUPnPNAT), (void **)&Nat);
if (FAILED(result)) Report("PortForward::Access CoCreateInstance IUPnPNAT failed");
else if (!Nat) Report("PortForward::Access CoCreateInstance succeeded, but left Nat null");
if (FAILED(result) || !Nat) return false;
// Get the collection of forwarded ports from it, has Windows send UPnP messages to the NAT router
result = Nat->get_StaticPortMappingCollection(&Collection); // Won't work if the NAT has UPnP turned off
if (FAILED(result)) Report("PortForward::Access Nat->get_StaticPortMappingCollection failed");
else if (!Collection) Report("PortForward::Access Nat->get_StaticPortMappingCollection succeeded, but left Collection null");
if (FAILED(result) || !Collection) return false; // Frequently, result is S_OK but Collection is null
// Everything worked
return true;
}
// Takes a protocol 't' for TCP or 'u' for UDP, the ports to forward externally and internally, and the program name and description
// Talks UPnP to the router to setup port forwarding
// Returns false if there was an error
bool PortForward::Add(char protocol, int externalport, int internalport, read ipaddress, read name) {
// Make a local BSTR with the protocol described in text
Beaster p;
if (protocol == 't') p.Set("TCP");
else p.Set("UDP");
// Express the name and description as BSTRs
Beaster i(ipaddress);
Beaster n(name);
// Have Windows send UPnP messages to the NAT router to get it to forward a port
if (Mapping) { Mapping->Release(); Mapping = NULL; } // Reuse the mapping interface pointer
HRESULT result = Collection->Add( // Create a new port mapping, and add it to the collection
externalport, // The port to forward
p.B, // The protocol as the text "TCP" or "UDP" in a BSTR
internalport, // This computer's internal LAN port to forward to, like 192.168.1.100:internalport
i.B, // Internal IP address to forward to, like "192.168.1.100"
true, // True to start forwarding now
n.B, // Description text the router can show in its Web configuration interface
&Mapping); // Access to the IStaticPortMapping interface, if this works
if (FAILED(result)) Report("PortForward::Add Collection->Add failed");
else if (!Mapping) Report("PortForward::Add Collection->Add succeeded, but left Mapping null");
if (FAILED(result) || !Mapping) return false;
return true;
}
UPnP port forwarding in Visual Basic
