#include <net-snmp/net-snmp-config.h>

#include <net-snmp/library/snmpSTDDomain.h>

#include <stdio.h>

#include <sys/types.h>

#include <signal.h>

#include <errno.h>

#ifdef HAVE_STRING_H

#include <string.h>

#else

#include <strings.h>

#endif

#ifdef HAVE_STDLIB_H

#include <stdlib.h>

#endif

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#include <net-snmp/types.h>

#include <net-snmp/output_api.h>

#include <net-snmp/library/snmp.h>

#include <net-snmp/library/snmp_transport.h>

#include <net-snmp/library/tools.h>

const oid netsnmp_snmpSTDDomain[] = { TRANSPORT_DOMAIN_STD_IP };

static netsnmp_tdomain stdDomain;

/*

 * Return a string representing the address in data, or else the "far end"

 * address if data is NULL.  

 */

static char *

netsnmp_std_fmtaddr(netsnmp_transport *t, const void *data, int len)

{

    DEBUGMSGTL(("domain:std","formatting addr.  data=%p\n",t->data));

    if (t->data) {

        netsnmp_std_data *data = (netsnmp_std_data*)t->data;

  char *buf;

        if (asprintf(&buf, "STD:%s", data->prog) < 0)

            buf = NULL;

        DEBUGMSGTL(("domain:std","  formatted:=%s\n",buf));

        return buf;

    }

    return strdup("STDInOut");

}

static void

netsnmp_std_get_taddr(netsnmp_transport *t, void **addr, size_t *addr_len)

{

    *addr_len = t->remote_length;

    *addr = netsnmp_memdup(t->remote, *addr_len);

}

/*

 * You can write something into opaque that will subsequently get passed back 

 * to your send function if you like.  For instance, you might want to

 * remember where a PDU came from, so that you can send a reply there...  

 */

static int

netsnmp_std_recv(netsnmp_transport *t, void *buf, int size,

     void **opaque, int *olength)

{

    int rc = -1;

    DEBUGMSGTL(("domain:std","recv on sock %d.  data=%p\n",t->sock, t->data));

    while (rc < 0) {

        rc = read(t->sock, buf, size);

        DEBUGMSGTL(("domain:std","  bytes: %d.\n", rc));

        if (rc < 0 && errno != EINTR) {

            DEBUGMSGTL(("netsnmp_std", " read on fd %d failed: %d (\"%s\")\n",

                        t->sock, errno, strerror(errno)));

            break;

        }

        if (rc == 0) {

            /* 0 input is probably bad since we selected on it */

            return -1;

        }

        DEBUGMSGTL(("netsnmp_std", "read on stdin got %d bytes\n", rc));

    }

    return rc;

}

static int

netsnmp_std_send(netsnmp_transport *t, const void *buf, int size,

     void **opaque, int *olength)

{

    int rc = -1;

    DEBUGMSGTL(("domain:std","send on sock.  data=%p\n", t->data));

    while (rc < 0) {

        if (t->data) {

            netsnmp_std_data *data = (netsnmp_std_data*)t->data;

            rc = write(data->outfd, buf, size);

        } else {

            /* straight to stdout */

            rc = write(1, buf, size);

        }

        if (rc < 0 && errno != EINTR) {

            break;

        }

    }

    return rc;

}

static int

netsnmp_std_close(netsnmp_transport *t)

{

    DEBUGMSGTL(("domain:std","close.  data=%p\n", t->data));

    if (t->data) {

        netsnmp_std_data *data = (netsnmp_std_data*)t->data;

        close(data->outfd);

        close(t->sock);

        /* kill the child too */

        DEBUGMSGTL(("domain:std"," killing %d\n", data->childpid));

        kill(data->childpid, SIGTERM);

        sleep(1);

        kill(data->childpid, SIGKILL);

        /* XXX: set an alarm to kill harder the child */

    } else {

        /* close stdout/in */

        close(STDOUT_FILENO);

        close(STDIN_FILENO);

    }

    return 0;

}

static int

netsnmp_std_accept(netsnmp_transport *t)

{

    DEBUGMSGTL(("domain:std"," accept data=%p\n", t->data));

    /* nothing to do here */

    return 0;

}

/*

 * Open a STDIN/STDOUT -based transport for SNMP.

 */

netsnmp_transport *

netsnmp_std_transport(const char *instring, size_t instring_len,

          const char *default_target)

{

    netsnmp_transport *t;

    t = SNMP_MALLOC_TYPEDEF(netsnmp_transport);

    if (t == NULL) {

        return NULL;

    }

    t->domain = netsnmp_snmpSTDDomain;

    t->domain_length =

        sizeof(netsnmp_snmpSTDDomain) / sizeof(netsnmp_snmpSTDDomain[0]);

    t->sock = -1;

    t->flags = NETSNMP_TRANSPORT_FLAG_STREAM | NETSNMP_TRANSPORT_FLAG_TUNNELED;

    /*

     * Message size is not limited by this transport (hence msgMaxSize

     * is equal to the maximum legal size of an SNMP message).  

     */

    t->msgMaxSize = SNMP_MAX_PACKET_LEN;

    t->f_recv     = netsnmp_std_recv;

    t->f_send     = netsnmp_std_send;

    t->f_close    = netsnmp_std_close;

    t->f_accept   = netsnmp_std_accept;

    t->f_fmtaddr  = netsnmp_std_fmtaddr;

    t->f_get_taddr = netsnmp_std_get_taddr;

    /*

     * if instring is not null length, it specifies a path to a prog

     * XXX: plus args

     */

    if (instring_len == 0 && default_target != NULL) {

  instring = default_target;

  instring_len = strlen(default_target);

    }

    if (instring_len != 0) {

        int infd[2], outfd[2];  /* sockets to and from the client */

        int childpid;

        if (pipe(infd) || pipe(outfd)) {

            snmp_log(LOG_ERR,

                     "Failed to create needed pipes for a STD transport");

            netsnmp_transport_free(t);

            return NULL;

        }

        childpid = fork();

        /* parentpid => childpid */

        /* infd[1]   => infd[0] */

        /* outfd[0]  <= outfd[1] */

        if (childpid) {

            netsnmp_std_data *data;

            /* we're in the parent */

            close(infd[0]);

            close(outfd[1]);

            data = SNMP_MALLOC_TYPEDEF(netsnmp_std_data);

            if (!data) {

                snmp_log(LOG_ERR, "snmpSTDDomain: malloc failed");

                netsnmp_transport_free(t);

                return NULL;

            }

            t->data = data;

            t->data_length = sizeof(netsnmp_std_data);

            t->sock = outfd[0];

            data->prog = strdup(instring);

            data->outfd = infd[1];

            data->childpid = childpid;

            DEBUGMSGTL(("domain:std","parent.  data=%p\n", t->data));

        } else {

            /* we're in the child */

            dup2(infd[0], STDIN_FILENO);

            dup2(outfd[1], STDOUT_FILENO);

            /* close all the pipes themselves */

            close(infd[0]);

            close(infd[1]);

            close(outfd[0]);

            close(outfd[1]);

            /* call exec */

            NETSNMP_IGNORE_RESULT(system(instring));

            /* XXX: TODO: use exec form instead; needs args */

            /* execv(instring, NULL); */

            exit(0);

            /* ack...  we should never ever get here */

            snmp_log(LOG_ERR, "STD transport returned after execv()\n");

        }

    }            

    return t;

}

netsnmp_transport *

netsnmp_std_create_tstring(const char *instring, int local,

         const char *default_target)

{

    return netsnmp_std_transport(instring, strlen(instring), default_target);

}

netsnmp_transport *

netsnmp_std_create_ostring(const void *o, size_t o_len, int local)

{

    return netsnmp_std_transport(o, o_len, NULL);

}

void

netsnmp_std_ctor(void)

{

    stdDomain.name = netsnmp_snmpSTDDomain;

    stdDomain.name_length = OID_LENGTH(netsnmp_snmpSTDDomain);

    stdDomain.prefix = calloc(2, sizeof(char *));

    if (!stdDomain.prefix) {

        snmp_log(LOG_ERR, "calloc() failed - out of memory\n");

        return;

    }

    stdDomain.prefix[0] = "std";

    stdDomain.f_create_from_tstring_new = netsnmp_std_create_tstring;

    stdDomain.f_create_from_ostring     = netsnmp_std_create_ostring;

    netsnmp_tdomain_register(&stdDomain);

}