mctpd: respond to Get EID using physical addressing

Currently, mctpd running as an endpoint with no EID set cannot reply to
Get EID message, due to having no routing knowledge and we currently
use EID-based routing for the response.

This uses physical addressing for Get Endpoint message.

Signed-off-by: Khang D Nguyen <[email protected]>

Author: khangng-ampere

src/mctpd.c

@@ -570,6 +570,29 @@ static int read_message(struct ctx *ctx, int sd, uint8_t **ret_buf, size_t *ret_
 	return rc;
 }
 
+/* Replies to a physical address */
+static int reply_message_phys(struct ctx *ctx, int sd, const void *resp, size_t resp_len,
+	const struct sockaddr_mctp_ext *addr)
+{
+	ssize_t len;
+	struct sockaddr_mctp_ext reply_addr = *addr;
+
+	reply_addr.smctp_base.smctp_tag &= ~MCTP_TAG_OWNER;
+
+	len = mctp_ops.mctp.sendto(sd, resp, resp_len, 0,
+				   (struct sockaddr *)&reply_addr,
+				   sizeof(reply_addr));
+	if (len < 0) {
+		return -errno;
+	}
+
+	if ((size_t)len != resp_len) {
+		bug_warn("short sendto %zd, expected %zu", len, resp_len);
+		return -EPROTO;
+	}
+	return 0;
+}
+
 /* Replies to a real EID, not physical addressing */
 static int reply_message(struct ctx *ctx, int sd, const void *resp, size_t resp_len,
 	const struct sockaddr_mctp_ext *addr)
@@ -694,7 +717,8 @@ static int handle_control_get_endpoint_id(struct ctx *ctx,
 	SET_ENDPOINT_ID_TYPE(resp->eid_type, 2);
 	// TODO: medium specific information
 
-	return reply_message(ctx, sd, resp, sizeof(*resp), addr);
+	// Get Endpoint ID is typically send and reply using physical addressing.
+	return reply_message_phys(ctx, sd, resp, sizeof(*resp), addr);
 }
 
 static int handle_control_get_endpoint_uuid(struct ctx *ctx,

tests/test_mctpd_endpoint.py

@@ -2,14 +2,35 @@
 from mctp_test_utils import *
 from mctpd import *
 
-@pytest.fixture(name="config")
-def endpoint_config():
+@pytest.fixture
+def config():
     return """
     mode = "endpoint"
     """
 
+@pytest.fixture
+async def sysnet():
+    system = System()
+    iface = System.Interface("mctp0", 1, 1, bytes([0x1D]), 68, 254, True)
+    await system.add_interface(iface)
+    network = Network()
+    network.add_endpoint(Endpoint(iface, bytes([0x10]), eid=8))
+    return Sysnet(system, network)
+
+
 """ Test if mctpd is running as an endpoint """
 async def test_endpoint_role(dbus, mctpd):
     obj = await mctpd_mctp_iface_control_obj(dbus, mctpd.system.interfaces[0])
     role = await obj.get_role()
     assert str(role) == "Endpoint"
+
+
+""" mctpd returns null EID on no EID """
+async def test_respond_get_eid_with_no_eid(dbus, mctpd):
+    bo = mctpd.network.endpoints[0]
+
+    assert len(mctpd.system.addresses) == 0
+
+    # no EID yet
+    rsp = await bo.send_control(mctpd.network.mctp_socket, 0x02)
+    assert rsp.hex(' ') == '00 02 00 00 02 00'