xref: /openbmc/pldm/common/transport.hpp (revision 21f128d8)
1 #pragma once
2 
3 #include <libpldm/base.h>
4 #include <libpldm/pldm.h>
5 #include <poll.h>
6 #include <stddef.h>
7 
8 struct pldm_transport_mctp_demux;
9 struct pldm_transport_af_mctp;
10 
11 union TransportImpl
12 {
13     struct pldm_transport_mctp_demux* mctp_demux;
14     struct pldm_transport_af_mctp* af_mctp;
15 };
16 
17 /* RAII for pldm_transport */
18 class PldmTransport
19 {
20   public:
21     PldmTransport();
22     PldmTransport(const PldmTransport& other) = delete;
23     PldmTransport(const PldmTransport&& other) = delete;
24     PldmTransport& operator=(const PldmTransport& other) = delete;
25     PldmTransport& operator=(const PldmTransport&& other) = delete;
26     ~PldmTransport();
27 
28     /** @brief Provides a file descriptor that can be polled for readiness.
29      *
30      * Readiness generally indicates that a call to recvMsg() will immediately
31      * yield a message.
32      *
33      * @return The relevant file descriptor.
34      */
35     int getEventSource() const;
36 
37     /** @brief Asynchronously send a PLDM message to the specified terminus
38      *
39      * The message may be either a request or a response.
40      *
41      * @param[in] tid - The terminus ID of the message destination
42      * @param[in] tx - The encoded and framed message to send
43      * @param[in] len - The length of the buffer pointed-to by tx
44      *
45      * @return PLDM_REQUESTER_SUCCESS on success, otherwise an appropriate
46      *         PLDM_REQUESTER_* error code.
47      */
48     pldm_requester_rc_t sendMsg(pldm_tid_t tid, const void* tx, size_t len);
49 
50     /** @brief Asynchronously receive a PLDM message addressed to the local
51      * terminus
52      *
53      * The message may be either a request or a response.
54      *
55      * @param[out] tid - The terminus ID of the message source
56      * @param[out] rx - A pointer to the received, encoded message
57      * @param[out] len - The length of the buffer pointed-to by rx
58      *
59      * @return PLDM_REQUESTER_SUCCESS on success, otherwise an appropriate
60      *         PLDM_REQUESTER_* error code.
61      */
62     pldm_requester_rc_t recvMsg(pldm_tid_t& tid, void*& rx, size_t& len);
63 
64     /** @brief Synchronously exchange a request and response with the specified
65      * terminus.
66      *
67      * sendRecvMsg() is a wrapper for the non-compliant
68      * pldm_transport_send_recv_msg() API from libpldm. It is a crutch that may
69      * be used for to fulfil a PLDM request until libpldm implements a correct
70      * requester flow in accordance with the PLDM base specification (DSP0240).
71      *
72      * The implementation blocks after the request is sent until a response is
73      * received, or the upper time-bound on a PLDM exchange is reached. Control
74      * is only handed back to the caller once one of these two outcomes is
75      * achieved.
76      *
77      * @param[in] tid - The terminus ID of the endpoint with which the exchange
78      *                  will occur
79      * @param[in] tx - The encoded and framed message to send
80      * @param[in] txLen - The length of the buffer pointed-to by tx
81      * @param[out] rx - A pointer to the received, encoded message
82      * @param[out] rxLen - The length of the buffer pointed-to by rx
83      *
84      * @return PLDM_REQUESTER_SUCCESS on success, otherwise an appropriate
85      *         PLDM_REQUESTER_* error code.
86      */
87     pldm_requester_rc_t sendRecvMsg(pldm_tid_t tid, const void* tx,
88                                     size_t txLen, void*& rx, size_t& rxLen);
89 
90   private:
91     /** @brief A pollfd object for holding a file descriptor from the libpldm
92      *         transport implementation
93      */
94     pollfd pfd;
95 
96     /** @brief A union holding an appropriately-typed pointer to the selected
97      *         libpldm transport implementation
98      */
99     TransportImpl impl;
100 
101     /** @brief The abstract libpldm transport object for sending and receiving
102      *         PLDM messages.
103      */
104     struct pldm_transport* transport;
105 };
106