cmd/ldmad/ldmad.c

	ldmad.c revision 6b8303caf3c5c70ae1c1d362bf6de0c55eb622bb
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Logical Domains (LDoms) Agents Daemon
 *
 * The LDoms agents daemon (ldmad) runs on LDoms domains and provides
 * information to the control domain. It is composed of a set of agents
 * which can send and receive messages to and from the control domain.
 * Each agent is registered as a domain service using the libds library,
 * and is able to handle requests coming from the control domain.
 *
 * The control domain sends requests to an agent as messages on the
 * corresponding domain service (identified by the agent name). All requests
 * are received by the ldmad daemon which dispatches them to the appropriate
 * handler function of the agent depending on the type of the message.
 *
 * After the request has been processed by the handler, the ldmad daemon sent
 * a reply message back to the control domain. The reply is either a result
 * message if the request was successfully completed, or an error message
 * describing the failure.
 */

#include <dirent.h>
#include <dlfcn.h>
#include <errno.h>
#include <fcntl.h>
#include <link.h>
#include <libds.h>
#include <libgen.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <syslog.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>

#include "ldma.h"

#define LDMA_MODULE "ldm-agent-daemon"

#define LDMA_CONTROL_DOMAIN_DHDL    0   /* id of the control domain */
#define LDMA_DOMAIN_NAME_MAXLEN     MAXNAMELEN

typedef struct ldma_agent {
    ldma_agent_info_t   *info;      /* agent information */
    ds_hdl_t        conn_hdl;   /* connexion handler */
    ds_ver_t        conn_ver;   /* connexion version */
} ldma_agent_t;

/* information about existing agents */
extern ldma_agent_info_t ldma_device_info;
extern ldma_agent_info_t ldma_system_info;

boolean_t ldma_debug = B_FALSE;
boolean_t ldma_daemon = B_FALSE;

static ldma_agent_info_t *ldma_agent_infos[] = {
    &ldma_device_info,
    &ldma_system_info,
    NULL
};

static char *cmdname;
static pid_t daemon_pid = 0;

/*
 * Allocate a new message with the specified message number (msg_num),
 * message type (msg_type) and message data length (msg_dlen). Return
 * NULL if the allocation has failed.
 */
static ldma_message_header_t *
ldma_alloc_msg(uint64_t msg_num, uint32_t msg_type, size_t msg_dlen)
{
    ldma_message_header_t *msg;
    size_t msg_len;

    msg_len = LDMA_MESSAGE_SIZE(msg_dlen);
    msg = malloc(msg_len);
    if (msg == NULL)
        return (NULL);

    msg->msg_num = msg_num;
    msg->msg_type = msg_type;
    msg->msg_info = 0;

    return (msg);
}

/*
 * Allocate a result message (LDMA_MSG_REQ_RESULT) with the specified message
 * data length (msg_dlen). If the request argument is not NULL then the message
 * is created with the same message number as the request, otherwise the message
 * number is set to 0. Return NULL if the allocation has failed.
 */
ldma_message_header_t *
ldma_alloc_result_msg(ldma_message_header_t *request, size_t msg_dlen)
{
    uint64_t msg_num;

    msg_num = (request == NULL)? 0 : request->msg_num;

    return (ldma_alloc_msg(msg_num, LDMA_MSG_RESULT, msg_dlen));
}

/*
 * Agent register callback. This callback is invoked when a client is registered
 * for using the service provided by an agent. An agent will only have one
 * consumer which is coming from the control domain.
 */
static void
ldma_reg_cb(ds_hdl_t hdl, ds_cb_arg_t arg, ds_ver_t *ver,
    ds_domain_hdl_t dhdl)
{
    ldma_agent_t *agent = (ldma_agent_t *)arg;
    char dname[LDMA_DOMAIN_NAME_MAXLEN];

    if (ds_dom_hdl_to_name(dhdl, dname, LDMA_DOMAIN_NAME_MAXLEN) != 0) {
        (void) strcpy(dname, "<unknown>");
    }

    LDMA_DBG("%s: REGISTER hdl=%llx, dhdl=%llx (%s) ver=%hd.%hd",
        agent->info->name, hdl, dhdl, dname, ver->major, ver->minor);

    /*
     * Record client information if the connexion is from the control
     * domain. The domain service framework only allows connexion of a
     * domain with the control domain. However, if the agent is running
     * on the control domain then it can see connexions coming from any
     * domains. That's why we explicitly have to check if the connexion
     * is effectively with the control domain.
     */
    if (dhdl == LDMA_CONTROL_DOMAIN_DHDL) {
        agent->conn_hdl = hdl;
        agent->conn_ver.major = ver->major;
        agent->conn_ver.minor = ver->minor;
    } else {
        LDMA_INFO("agent %s will ignore any request from distrusted "
            "domain %s", agent->info->name, dname);
    }
}

/*
 * Agent unregister callback. This callback is invoked when a client is
 * unregistered and stops using the service provided by an agent.
 */
static void
ldma_unreg_cb(ds_hdl_t hdl, ds_cb_arg_t arg)
{
    ldma_agent_t *agent = (ldma_agent_t *)arg;

    LDMA_DBG("%s: UNREGISTER hdl=%llx", agent->info->name, hdl);

    if (agent->conn_hdl == hdl) {
        agent->conn_hdl = 0;
        agent->conn_ver.major = 0;
        agent->conn_ver.minor = 0;
    } else {
        LDMA_INFO("agent %s has unregistered consumer from "
            "distrusted domain", agent->info->name);
    }
}

/*
 * Agent data callback. This callback is invoked when an agent receives a new
 * message from a client. Any request from a client which is not the control
 * domain is immediatly rejected. Otherwise the message is forwarded to the
 * appropriate handler function provided by the agent, depending on the message
 * type.
 */
static void
ldma_data_cb(ds_hdl_t hdl, ds_cb_arg_t arg, void *buf, size_t len)
{
    ldma_agent_t *agent = (ldma_agent_t *)arg;
    ldma_msg_handler_t *handler;
    ldma_message_header_t *request = buf;
    ldma_message_header_t *reply = NULL;
    ldma_request_status_t status;
    size_t request_dlen, reply_len, reply_dlen = 0;
    int i;

    /* check the message size */
    if (len < LDMA_MESSAGE_HEADER_SIZE) {
        LDMA_INFO("agent %s has ignored message with an invalid "
            "size of %d bytes", agent->info->name, len);
        return;
    }

    request_dlen = LDMA_MESSAGE_DLEN(len);

    LDMA_DBG("%s: DATA hdl=%llx, request num=%llu type=0x%x info=0x%x "
        "dlen=%d", agent->info->name, hdl, request->msg_num,
        request->msg_type, request->msg_info, request_dlen);

    /* reject any request which is not from the control domain */
    if (hdl != agent->conn_hdl) {
        LDMA_DBG("%s: DATA hdl=%llx, rejecting request from a "
            "distrusted domain", agent->info->name, hdl);
        status = LDMA_REQ_DENIED;
        goto do_reply;
    }

    handler = NULL;

    for (i = 0; i < agent->info->nhandlers; i++) {
        if (agent->info->handlers[i].msg_type == request->msg_type) {
            handler = &agent->info->handlers[i];
            break;
        }
    }

    if (handler == NULL) {
        /* this type of message is not defined by the agent */
        LDMA_DBG("%s: DATA hdl=%llx, unknown message type %x",
            agent->info->name, hdl, request->msg_type);
        status = LDMA_REQ_NOTSUP;
        goto do_reply;
    }

    if (handler->msg_handler == NULL) {
        /*
         * This type of message is defined by the agent but it
         * has no handler. That means there is no processing to
         * do, the message is just ignored, but the request is
         * successfully completed.
         */
        LDMA_DBG("%s: DATA hdl=%llx, no handler",
            agent->info->name, hdl);
        status = LDMA_REQ_COMPLETED;
        goto do_reply;
    }

    /* invoke the message handler of the agent */
    status = (*handler->msg_handler)(&agent->conn_ver, request,
        request_dlen, &reply, &reply_dlen);

    LDMA_DBG("%s: DATA hdl=%llx, handler stat=%d reply=%p rlen=%d",
        agent->info->name, hdl, status, (void *)reply, reply_dlen);

do_reply:
    /*
     * If the handler has provided a reply message, we use it directly.
     * Otherwise, we build a reply depending on the status of the request.
     * In that case, we re-use the request buffer to build the reply
     * message.
     */
    if (reply == NULL) {

        reply = request;
        reply_dlen = 0;

        if (status == LDMA_REQ_COMPLETED) {
            /*
             * The request was successful but no result message was
             * provided so we send an empty result message.
             */
            reply->msg_type = LDMA_MSG_RESULT;
            reply->msg_info = 0;

        } else {
            /*
             * The request has failed but no error message was
             * provided so we send an error message based on the
             * request status.
             */
            reply->msg_type = LDMA_MSG_ERROR;
            reply->msg_info =
                (status == LDMA_REQ_NOTSUP)? LDMA_MSGERR_NOTSUP :
                (status == LDMA_REQ_INVALID)? LDMA_MSGERR_INVALID :
                (status == LDMA_REQ_DENIED)? LDMA_MSGERR_DENY :
                LDMA_MSGERR_FAIL;
        }
    }

    reply_len = LDMA_MESSAGE_SIZE(reply_dlen);

    LDMA_DBG("%s: DATA hdl=%llx, reply num=%llu type=0x%x info=0x%x "
        "dlen=%d", agent->info->name, hdl, reply->msg_num,
        reply->msg_type, reply->msg_info, reply_dlen);

    if (ds_send_msg(hdl, reply, reply_len) != 0) {
        LDMA_ERR("agent %s has failed to send reply for request %llu",
            agent->info->name, request->msg_num);
    }

    if (reply != request)
        free(reply);
}

/*
 * Register an agent. Return 0 if the agent was successfully registered.
 */
static int
ldma_register(ldma_agent_info_t *agent_info)
{
    ldma_agent_t    *agent;
    ds_capability_t ds_cap;
    ds_ops_t    ds_ops;

    agent = malloc(sizeof (ldma_agent_t));
    if (agent == NULL)
        goto register_fail;

    agent->info = agent_info;
    agent->conn_hdl = 0;
    agent->conn_ver.major = 0;
    agent->conn_ver.minor = 0;

    ds_cap.svc_id = agent_info->name;
    ds_cap.vers = agent_info->vers;
    ds_cap.nvers = agent_info->nvers;

    ds_ops.ds_reg_cb = ldma_reg_cb;
    ds_ops.ds_unreg_cb = ldma_unreg_cb;
    ds_ops.ds_data_cb = ldma_data_cb;
    ds_ops.cb_arg = agent;

    if (ds_svc_reg(&ds_cap, &ds_ops) == 0) {
        LDMA_INFO("agent %s registered", agent_info->name);
        return (0);
    }

register_fail:

    LDMA_ERR("agent %s has failed to register", agent_info->name);
    free(agent);
    return (-1);
}

/*
 * Register all known agents. Return the number of agents successfully
 * registered.
 */
static int
ldma_register_agents()
{
    int count = 0;
    ldma_agent_info_t **agent_infop;

    for (agent_infop = ldma_agent_infos;
        *agent_infop != NULL; agent_infop++) {

        if (ldma_register(*agent_infop) == 0)
            count++;
    }

    return (count);
}

/*ARGSUSED*/
static void
ldma_sigusr_handler(int sig, siginfo_t *sinfo, void *ucontext)
{
    /*
     * The child process can send the signal before the fork()
     * call has returned in the parent process. So daemon_pid
     * may not be set yet, and we don't check the pid in that
     * case.
     */
    if (sig != SIGUSR1 || sinfo->si_code != SI_USER ||
        (daemon_pid > 0 && sinfo->si_pid != daemon_pid))
        return;

    /*
     * The parent process has received a USR1 signal from the child.
     * This means that the daemon has correctly started and the parent
     * can exit.
     */
    exit(0);
}

static void
ldma_start(boolean_t standalone)
{
    int stat, rv;
    struct sigaction action;

    if (!standalone) {
        /*
         * Some configuration of the daemon has to be done in the
         * child, but we want the parent to report if the daemon
         * has successfully started or not. So we setup a signal
         * handler, and the child will notify the parent using the
         * USR1 signal if the setup was successful. Otherwise the
         * child will exit.
         */
        action.sa_sigaction = ldma_sigusr_handler;
        action.sa_flags = SA_SIGINFO;

        if (sigemptyset(&action.sa_mask) == -1) {
            LDMA_ERR("sigemptyset error (%d)", errno);
            exit(1);
        }

        if (sigaction(SIGUSR1, &action, NULL) == -1) {
            LDMA_ERR("sigaction() error (%d)", errno);
            exit(1);
        }

        if (sigrelse(SIGUSR1) == -1) {
            LDMA_ERR("sigrelse() error (%d)", errno);
            exit(1);
        }

        if ((daemon_pid = fork()) == -1) {
            LDMA_ERR("fork() error (%d)", errno);
            exit(1);
        }

        if (daemon_pid != 0) {
            /*
             * The parent process waits until the child exits (in
             * case of an error) or sends a USR1 signal (if the
             * daemon has correctly started).
             */
            for (;;) {
                rv = waitpid(daemon_pid, &stat, 0);
                if ((rv == daemon_pid && WIFEXITED(stat)) ||
                    (rv == -1 && errno != EINTR)) {
                    /* child has exited or error */
                    exit(1);
                }
            }
        }

        /*
         * Initialize child process
         */
        if (sighold(SIGUSR1) == -1) {
            LDMA_ERR("sighold error (%d)", errno);
            exit(1);
        }

        if (sigignore(SIGUSR1) == -1) {
            LDMA_ERR("sigignore error (%d)", errno);
            exit(1);
        }

        if (setsid() == -1) {
            LDMA_ERR("setsid error (%d)", errno);
            exit(1);
        }

        if (chdir("/") == -1) {
            LDMA_ERR("chdir error (%d)", errno);
            exit(1);
        }
        (void) umask(0);

        /*
         * Initialize file descriptors. Do not touch stderr
         * which is initialized by SMF to point to the daemon
         * specific log file.
         */
        (void) close(STDIN_FILENO);
        if (open("/dev/null", O_RDWR) == -1) {
            LDMA_ERR("open /dev/null error (%d)", errno);
            exit(1);
        }
        if (dup2(STDIN_FILENO, STDOUT_FILENO) == -1) {
            LDMA_ERR("dup2 error (%d)", errno);
            exit(1);
        }
        closefrom(STDERR_FILENO + 1);

        /* initialize logging */
        openlog(cmdname, LOG_CONS | LOG_NDELAY, LOG_DAEMON);

        ldma_daemon = B_TRUE;
    }

    /*
     * Register the agents. It would be easier to do this before
     * daemonizing so that any start error is directly reported. But
     * this can not be done because agents are registered using libds
     * and this will subscribe the daemon to some sysevents which is
     * a process based subscription. Instead we notify the parent process
     * either by exiting, or by sending a SIGUSR1 signal.
     */
    if (ldma_register_agents() == 0) {
        /* no agent registered */
        LDMA_ERR("Unable to register any agent");
        exit(1);
    }

    if (!standalone) {
        /* signal parent that startup was successful */
        if (kill(getppid(), SIGUSR1) == -1)
            exit(1);
    }
}

static void
ldma_usage()
{
    (void) fprintf(stderr, "usage: %s\n", cmdname);
}

int
main(int argc, char *argv[])
{
    int opt;
    boolean_t standalone = B_FALSE;

    cmdname = basename(argv[0]);

    /* disable getopt error messages */
    opterr = 0;

    while ((opt = getopt(argc, argv, "ds")) != EOF) {

        switch (opt) {
        case 'd':
            ldma_debug = B_TRUE;
            break;
        case 's':
            standalone = B_TRUE;
            break;
        default:
            ldma_usage();
            exit(1);
        }
    }

    ldma_start(standalone);

    /*
     * Loop forever. Any incoming message will be received by libds and
     * forwarded to the agent data callback (ldma_data_cb()) where it
     * will be processed.
     */
    for (;;) {
        (void) pause();
    }

    /*NOTREACHED*/
    return (0);
}