Connection error in SPDM_EMU when using SPDM over MCTP

[amuthakrishnasamy]

Hi Jiewen,

I am creating requester and responder model using SPDM_EMU.
Raspberry pi is used to simulate requester model and Riscv32 processor to used to simulate responder model.
Requester and responder is connected thru I2C.
However, for requester implementation in https://github.com/DMTF/spdm-emu/blob/main/spdm_emu/spdm_emu_common/spdm_emu.c SPDM_EMU, init_client function, I see the socket communication is happening thru TCP packet
bool init_client(SOCKET *sock, uint16_t port)
{
SOCKET client_socket;
struct sockaddr_in server_addr;
int32_t ret_val;

#ifdef _MSC_VER
WSADATA ws;
if (WSAStartup(MAKEWORD(2, 2), &ws) != 0) {
printf("Init Windows socket Failed - %x\n", WSAGetLastError());
return false;
}
#endif
client_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (client_socket == INVALID_SOCKET) {
printf("Create socket Failed - %x\n",
#ifdef _MSC_VER
WSAGetLastError()
#else
errno
#endif
);
return false;
}

I am getting connection error ( on requester side) due to there is no TCP connection between requester and responder.
What would be the suggested implementation that I can use to make connection between requester and responder over MCTP transport layer and I2C/SMBUS.

Thanks
AKrishnasamy

[jyao1]

spdm-emu is just an emulation program running on Windows/Linux OS environment with TCP/IP.

If you want to use it MCTP, then it is NOT an emulation. It is a real platform environment.
You need to write your own device layer function to send/receive function.

See https://github.com/DMTF/libspdm/blob/main/doc/user_guide.md#spdm-responder

0.5, implement required SPDM device IO functions - libspdm_device_send_message_func and libspdm_device_receive_message_func according to spdm_common_lib.

[admiyo]

If I run --trans MCTP it still does everything as tcp/ip.

MCTP supports a socket layer, so instead of listening on tcp, it should listen on an MCTP socket, like the echo listener here:

https://github.com/CodeConstruct/mctp/blob/main/src/mctp-echo.c

But all the socket calls are TCP/IP.

Is this a change in how it was intended to be used?

[alistair23]

Another option is to use SPDM-Utils. Like spdm-emu it uses libspdm but is aimed at testing real devices instead of emulators.

SPDM-Utils can currently communicate with a SPDM device over PCIe DOE. We don't yet have MCTP support, but we are working on it. It should be pretty easy for you to extend SPDM-Utils to support MCTP as well