ipmid.C

#include <stdio.h>
#include <dlfcn.h>
#include <iostream>
#include <unistd.h>
#include <assert.h>
#include <dirent.h>
#include <systemd/sd-bus.h>
#include <string.h>
#include <stdlib.h>
#include <map>
#include "ipmid.H"
#include <sys/time.h>
#include <errno.h>


sd_bus *bus = NULL;

// Channel that is used for OpenBMC Barreleye
const char * DBUS_NAME = "org.openbmc.HostIpmi";
const char * OBJ_NAME = "/org/openbmc/HostIpmi/1";

const char * FILTER = "type='signal',sender='org.openbmc.HostIpmi',member='ReceivedMessage'";


typedef std::pair<ipmi_netfn_t, ipmi_cmd_t> ipmi_fn_cmd_t;
typedef std::pair<ipmid_callback_t, ipmi_context_t> ipmi_fn_context_t;

// Global data structure that contains the IPMI command handler's registrations.
std::map<ipmi_fn_cmd_t, ipmi_fn_context_t> g_ipmid_router_map;



#ifndef HEXDUMP_COLS
#define HEXDUMP_COLS 16
#endif

void hexdump(void *mem, size_t len)
{
        unsigned int i, j;
        
        for(i = 0; i < len + ((len % HEXDUMP_COLS) ? (HEXDUMP_COLS - len % HEXDUMP_COLS) : 0); i++)
        {
                /* print offset */
                if(i % HEXDUMP_COLS == 0)
                {
                        printf("0x%06x: ", i);
                }
 
                /* print hex data */
                if(i < len)
                {
                        printf("%02x ", 0xFF & ((char*)mem)[i]);
                }
                else /* end of block, just aligning for ASCII dump */
                {
                        printf("   ");
                }
                
                /* print ASCII dump */
                if(i % HEXDUMP_COLS == (HEXDUMP_COLS - 1))
                {
                        for(j = i - (HEXDUMP_COLS - 1); j <= i; j++)
                        {
                                if(j >= len) /* end of block, not really printing */
                                {
                                        putchar(' ');
                                }
                                else if(isprint(((char*)mem)[j])) /* printable char */
                                {
                                        putchar(0xFF & ((char*)mem)[j]);        
                                }
                                else /* other char */
                                {
                                        putchar('.');
                                }
                        }
                        putchar('\n');
                }
        }
}


// Method that gets called by shared libraries to get their command handlers registered
void ipmi_register_callback(ipmi_netfn_t netfn, ipmi_cmd_t cmd,
                       ipmi_context_t context, ipmid_callback_t handler)
{
    // Pack NetFn and Command in one.
    auto netfn_and_cmd = std::make_pair(netfn, cmd);

    // Pack Function handler and Data in another.
    auto handler_and_context = std::make_pair(handler, context);

    // Check if the registration has already been made..
    auto iter = g_ipmid_router_map.find(netfn_and_cmd);
    if(iter != g_ipmid_router_map.end())
    {
        fprintf(stderr,"ERROR : Duplicate registration for NetFn [0x%X], Cmd:[0x%X]\n",netfn, cmd);
    }
    else
    {
        // This is a fresh registration.. Add it to the map.
        g_ipmid_router_map.emplace(netfn_and_cmd, handler_and_context);
    }

    return;
}

// Looks at the map and calls corresponding handler functions.
ipmi_ret_t ipmi_netfn_router(ipmi_netfn_t netfn, ipmi_cmd_t cmd, ipmi_request_t request,
                      ipmi_response_t response, ipmi_data_len_t data_len)
{
    // return from the Command handlers.
    ipmi_ret_t rc = IPMI_CC_INVALID;

    // Walk the map that has the registered handlers and invoke the approprite
    // handlers for matching commands.
    auto iter = g_ipmid_router_map.find(std::make_pair(netfn, cmd));
    if(iter == g_ipmid_router_map.end())
    {
        printf("No registered handlers for NetFn:[0x%X], Cmd:[0x%X]"
               " trying Wilcard implementation \n",netfn, cmd);

        // Now that we did not find any specific [NetFn,Cmd], tuple, check for
        // NetFn, WildCard command present.
        iter = g_ipmid_router_map.find(std::make_pair(netfn, IPMI_CMD_WILDCARD));
        if(iter == g_ipmid_router_map.end())
        {
            printf("No Registered handlers for NetFn:[0x%X],Cmd:[0x%X]\n",netfn, IPMI_CMD_WILDCARD);

            // Respond with a 0xC1
            memcpy(response, &rc, IPMI_CC_LEN);
            *data_len = IPMI_CC_LEN;
            return rc;
        }
    }

#ifdef __IPMI_DEBUG__
    // We have either a perfect match -OR- a wild card atleast,
    printf("Calling Net function:[0x%X], Command:[0x%X]\n", netfn, cmd);
#endif

    // Extract the map data onto appropriate containers
    auto handler_and_context = iter->second;

    // Creating a pointer type casted to char* to make sure we advance 1 byte
    // when we advance pointer to next's address. advancing void * would not
    // make sense.
    char *respo = &((char *)response)[IPMI_CC_LEN];

    // Response message from the plugin goes into a byte post the base response
    rc = (handler_and_context.first) (netfn, cmd, request, respo,
                                      data_len, handler_and_context.second);
 
    // Now copy the return code that we got from handler and pack it in first
    // byte.
    memcpy(response, &rc, IPMI_CC_LEN);
 
    // Data length is now actual data + completion code.
    *data_len = *data_len + IPMI_CC_LEN;

    return rc;
}




static int send_ipmi_message(unsigned char seq, unsigned char netfn, unsigned char cmd, unsigned char *buf, unsigned char len) {

    sd_bus_error error = SD_BUS_ERROR_NULL;
    sd_bus_message *reply = NULL, *m=NULL;


    const char *path;
    int r, pty;


    r = sd_bus_message_new_method_call(bus,&m,DBUS_NAME,OBJ_NAME,DBUS_NAME,"sendMessage");
    if (r < 0) {
        fprintf(stderr, "Failed to add the method object: %s\n", strerror(-r));
        return -1;
    }


    // Needed to see what we get back from the handlers.
    data_len = msg_length;


    // Add the bytes needed for the methods to be called
    r = sd_bus_message_append(m, "yyy", seq, netfn, cmd);
    if (r < 0) {
        fprintf(stderr, "Failed add the netfn and others : %s\n", strerror(-r));
        return -1;
    }
   
    r = sd_bus_message_append_array(m, 'y', buf, len);
    if (r < 0) {
        fprintf(stderr, "Failed to add the string of response bytes: %s\n", strerror(-r));
        return -1;
    }



    // Call the IPMI responder on the bus so the message can be sent to the CEC
    r = sd_bus_call(bus, m, 0, &error, &reply);
    if (r < 0) {
        fprintf(stderr, "Failed to call the method: %s", strerror(-r));
        return -1;
    }

    r = sd_bus_message_read(reply, "x", &pty);
#ifdef __IPMI_DEBUG__
    printf("RC from the ipmi dbus method :%d \n", pty);
#endif    
    if (r < 0) {
       fprintf(stderr, "Failed to get a rc from the method: %s\n", strerror(-r));

    }


    sd_bus_error_free(&error);
    sd_bus_message_unref(m);


#ifdef __IPMI_DEBUG__
    printf("%d : %s\n", __LINE__, __PRETTY_FUNCTION__ );
#endif    
    return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;

}

static int handle_ipmi_command(sd_bus_message *m, void *user_data, sd_bus_error
                         *ret_error) {
    int r = 0;
    const char *msg = NULL;
    char sequence, netfn, cmd;
    const void *request;
    size_t sz;
    size_t resplen =MAX_IPMI_BUFFER;
    unsigned char response[MAX_IPMI_BUFFER];

    printf(" *** Received Signal: ");

    memset(response, 0, MAX_IPMI_BUFFER);

    r = sd_bus_message_read(m, "yyy",  &sequence, &netfn, &cmd);
    if (r < 0) {
        fprintf(stderr, "Failed to parse signal message: %s\n", strerror(-r));
        return -1;
    }

    r = sd_bus_message_read_array(m, 'y',  &request, &sz );
    if (r < 0) {
        fprintf(stderr, "Failed to parse signal message: %s\n", strerror(-r));
        return -1;
    }


    printf("Seq 0x%02x, NetFn 0x%02x, CMD: 0x%02x \n", sequence, netfn, cmd);
    hexdump((void*)request, sz);

    // Allow the length field to be used for both input and output of the 
    // ipmi call
    resplen = sz;

    // Now that we have parsed the entire byte array from the caller 
    // we can call the ipmi router to do the work...
    r = ipmi_netfn_router(netfn, cmd, (void *)request, (void *)response, &resplen);
    if(r != 0)
    {
        fprintf(stderr,"ERROR:[0x%X] handling NetFn:[0x%X], Cmd:[0x%X]\n",r, netfn, cmd);
    }

    printf("Response...\n");
    hexdump((void*)response, resplen);

    // Send the response buffer from the ipmi command
    r = send_ipmi_message(sequence, netfn, cmd, response, resplen);
    if (r < 0) {
        fprintf(stderr, "Failed to send the response message\n");
        return -1;
    }


    return 0;
}


//----------------------------------------------------------------------
// handler_select
// Select all the files ending with with .so. in the given diretcory
// @d: dirent structure containing the file name
//----------------------------------------------------------------------
int handler_select(const struct dirent *entry)
{
    // To hold ".so" from entry->d_name;
    char dname_copy[4] = {0};

    // We want to avoid checking for everything and isolate to the ones having
    // .so in them.
    if(strstr(entry->d_name, IPMI_PLUGIN_EXTN))
    {
        // It is possible that .so could be anywhere in the string but unlikely
        // But being careful here. Get the base address of the string, move 
        // until end and come back 3 steps and that gets what we need.
        strcpy(dname_copy, (entry->d_name + strlen(entry->d_name)-strlen(IPMI_PLUGIN_EXTN)));
        if(strcmp(dname_copy, IPMI_PLUGIN_EXTN) == 0)
        {
            return 1;
        }
    }
    return 0;
}

// This will do a dlopen of every .so in ipmi_lib_path and will dlopen everything so that they will
// register a callback handler 
void ipmi_register_callback_handlers(const char* ipmi_lib_path)
{
    // For walking the ipmi_lib_path
    struct dirent **handler_list;
    int num_handlers = 0;

    // This is used to check and abort if someone tries to register a bad one.
    void *lib_handler = NULL;

    if(ipmi_lib_path == NULL)
    {
        fprintf(stderr,"ERROR; No handlers to be registered for ipmi.. Aborting\n");
        assert(0);
    }
    else
    {
        // 1: Open ipmi_lib_path. Its usually "/usr/lib/phosphor-host-ipmid"
        // 2: Scan the directory for the files that end with .so
        // 3: For each one of them, just do a 'dlopen' so that they register 
        //    the handlers for callback routines.

        std::string handler_fqdn = ipmi_lib_path;
        
        // Append a "/" since we need to add the name of the .so. If there is
        // already a .so, adding one more is not any harm.
        handler_fqdn += "/";

        num_handlers = scandir(ipmi_lib_path, &handler_list, handler_select, alphasort);
        while(num_handlers--)
        {
            printf("Registering handler:[%s]\n",handler_list[num_handlers]->d_name);

            handler_fqdn += handler_list[num_handlers]->d_name;
            lib_handler = dlopen(handler_fqdn.c_str(), RTLD_NOW);
            if(lib_handler == NULL)
            {
                fprintf(stderr,"ERROR opening:[%s]\n",handler_list[num_handlers]->d_name);
                dlerror();
            }
            // Wipe the memory allocated for this particular entry.
            free(handler_list[num_handlers]);
        }
        // Done with all registration.
        free(handler_list);
    }

    // TODO : What to be done on the memory that is given by dlopen ?.
    return;
}

int main(int argc, char *argv[])
{
    sd_bus_slot *slot = NULL;
    int r;
    char *mode = NULL;


    // Register all the handlers that provider implementation to IPMI commands.
    ipmi_register_callback_handlers(HOST_IPMI_LIB_PATH);

#ifdef __IPMI_DEBUG__
    printf("Registered Function handlers:\n");

    // Print the registered handlers and their arguments.
    for(auto& iter : g_ipmid_router_map)
    {
        ipmi_fn_cmd_t fn_and_cmd = iter.first;
        printf("NETFN:[0x%X], cmd[0x%X]\n", fn_and_cmd.first, fn_and_cmd.second);  
    }
#endif


    /* Connect to system bus */
    r = sd_bus_open_system(&bus);
    if (r < 0) {
        fprintf(stderr, "Failed to connect to system bus: %s\n",
                strerror(-r));
        goto finish;
    }

    r = sd_bus_add_match(bus, &slot, FILTER, handle_ipmi_command, NULL);
    if (r < 0) {
        fprintf(stderr, "Failed: sd_bus_add_match: %s : %s\n", strerror(-r), FILTER);
        goto finish;
    }


    for (;;) {
        /* Process requests */

        r = sd_bus_process(bus, NULL);
        if (r < 0) {
            fprintf(stderr, "Failed to process bus: %s\n", strerror(-r));
            goto finish;
        }
        if (r > 0) {
            continue;
        }

        r = sd_bus_wait(bus, (uint64_t) - 1);
        if (r < 0) {
            fprintf(stderr, "Failed to wait on bus: %s\n", strerror(-r));
            goto finish;
        }
    }

finish:
    sd_bus_slot_unref(slot);
    sd_bus_unref(bus);
    return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;

}