snmplib/snmpUnixDomain.c

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

#include <stdio.h>
#include <sys/types.h>
#include <ctype.h>
#include <errno.h>

#if HAVE_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif
#if HAVE_STDLIB_H
#include <stdlib.h>
#endif
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#if HAVE_SYS_UN_H
#include <sys/un.h>
#endif

#if HAVE_DMALLOC_H
#include <dmalloc.h>
#endif

#include <net-snmp/types.h>
#include <net-snmp/output_api.h>
#include <net-snmp/config_api.h>

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


#ifndef NETSNMP_STREAM_QUEUE_LEN
#define NETSNMP_STREAM_QUEUE_LEN  5
#endif

#ifndef SUN_LEN
/*
 * Evaluate to actual length of the `sockaddr_un' structure.  
 */
#define SUN_LEN(ptr) ((size_t) (((struct sockaddr_un *) 0)->sun_path)         \
                      + strlen ((ptr)->sun_path))
#endif

oid netsnmp_UnixDomain[10] = { ENTERPRISE_MIB, 3, 3, 2 };
static netsnmp_tdomain unixDomain;


/*
 * This is the structure we use to hold transport-specific data.  
 */

typedef struct _sockaddr_un_pair {
    int             local;
    struct sockaddr_un server;
    struct sockaddr_un client;
} sockaddr_un_pair;


/*
 * Return a string representing the address in data, or else the "far end"
 * address if data is NULL.  
 */

static char *
netsnmp_unix_fmtaddr(netsnmp_transport *t, void *data, int len)
{
    struct sockaddr_un *to = NULL;

    if (data != NULL) {
        to = (struct sockaddr_un *) data;
    } else if (t != NULL && t->data != NULL) {
        to = &(((sockaddr_un_pair *) t->data)->server);
        len = SUN_LEN(to);
    }
    if (to == NULL) {
        /*
         * "Local IPC" is the Posix.1g term for Unix domain protocols,
         * according to W. R. Stevens, ``Unix Network Programming Volume I
         * Second Edition'', p. 374.
         */
        return strdup("Local IPC: unknown");
    } else if (to->sun_path[0] == 0) {
        /*
         * This is an abstract name.  We could render it as hex or something
         * but let's not worry about that for now.
         */
        return strdup("Local IPC: abstract");
    } else {
        char           *tmp = (char *) malloc(16 + len);
        if (tmp != NULL) {
            sprintf(tmp, "Local IPC: %s", to->sun_path);
        }
        return tmp;
    }
}



/*
 * 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_unix_recv(netsnmp_transport *t, void *buf, int size,
                  void **opaque, int *olength)
{
    int rc = -1;

    *opaque = NULL;
    *olength = 0;
    if (t != NULL && t->sock >= 0) {
	while (rc < 0) {
	    rc = recv(t->sock, buf, size, 0);
	    if (rc < 0 && errno != EINTR) {
		DEBUGMSGTL(("netsnmp_unix", "recv fd %d err %d (\"%s\")\n",
			    t->sock, errno, strerror(errno)));
		return rc;
	    }
	}
	DEBUGMSGTL(("netsnmp_unix", "recv fd %d got %d bytes\n", t->sock, rc));
    }
    return rc;
}



static int
netsnmp_unix_send(netsnmp_transport *t, void *buf, int size,
                  void **opaque, int *olength)
{
    int rc = -1;

    if (t != NULL && t->sock >= 0) {
        DEBUGMSGTL(("netsnmp_unix", "send %d bytes from %p on fd %d\n",
                    size, buf, t->sock));
	while (rc < 0) {
	    rc = send(t->sock, buf, size, 0);
	    if (rc < 0 && errno != EINTR) {
		break;
	    }
	}
    }
    return rc;
}



static int
netsnmp_unix_close(netsnmp_transport *t)
{
    int rc = 0;
    sockaddr_un_pair *sup = (sockaddr_un_pair *) t->data;

    if (t->sock >= 0) {
#ifndef HAVE_CLOSESOCKET
        rc = close(t->sock);
#else
        rc = closesocket(t->sock);
#endif
        t->sock = -1;
        if (sup != NULL) {
            if (sup->local) {
                DEBUGMSGTL(("netsnmp_unix", "close: server unlink(\"%s\")\n",
                            sup->server.sun_path));
                unlink(sup->server.sun_path);
            } else {
                DEBUGMSGTL(("netsnmp_unix", "close: client unlink(\"%s\")\n",
                            sup->client.sun_path));
                unlink(sup->client.sun_path);
            }
        }
        return rc;
    } else {
        return -1;
    }
}



static int
netsnmp_unix_accept(netsnmp_transport *t)
{
    struct sockaddr *farend = NULL;
    int             newsock = -1;
    socklen_t       farendlen = sizeof(struct sockaddr_un);

    farend = (struct sockaddr *) malloc(farendlen);

    if (farend == NULL) {
        /*
         * Indicate that the acceptance of this socket failed.  
         */
        DEBUGMSGTL(("netsnmp_unix", "accept: malloc failed\n"));
        return -1;
    }
    memset(farend, 0, farendlen);

    if (t != NULL && t->sock >= 0) {
        newsock = accept(t->sock, farend, &farendlen);

        if (newsock < 0) {
            DEBUGMSGTL(("netsnmp_unix","accept failed rc %d errno %d \"%s\"\n",
			newsock, errno, strerror(errno)));
            free(farend);
            return newsock;
        }

        if (t->data != NULL) {
            free(t->data);
        }

        DEBUGMSGTL(("netsnmp_unix", "accept succeeded (farend %p len %d)\n",
		    farend, farendlen));
        t->data = farend;
        t->data_length = sizeof(struct sockaddr_un);
        return newsock;
    } else {
        free(farend);
        return -1;
    }
}



/*
 * Open a Unix-domain transport for SNMP.  Local is TRUE if addr is the local 
 * address to bind to (i.e. this is a server-type session); otherwise addr is 
 * the remote address to send things to (and we make up a temporary name for
 * the local end of the connection).  
 */

netsnmp_transport *
netsnmp_unix_transport(struct sockaddr_un *addr, int local)
{
    netsnmp_transport *t = NULL;
    sockaddr_un_pair *sup = NULL;
    int             rc = 0;
    char           *string = NULL;

    if (addr == NULL || addr->sun_family != AF_UNIX) {
        return NULL;
    }

    t = (netsnmp_transport *) malloc(sizeof(netsnmp_transport));
    if (t == NULL) {
        return NULL;
    }

    string = netsnmp_unix_fmtaddr(NULL, (void *)addr, 
				  sizeof(struct sockaddr_un));
    DEBUGMSGTL(("netsnmp_unix", "open %s %s\n", local ? "local" : "remote",
                string));
    free(string);

    memset(t, 0, sizeof(netsnmp_transport));

    t->domain = netsnmp_UnixDomain;
    t->domain_length =
        sizeof(netsnmp_UnixDomain) / sizeof(netsnmp_UnixDomain[0]);

    t->data = malloc(sizeof(sockaddr_un_pair));
    if (t->data == NULL) {
        netsnmp_transport_free(t);
        return NULL;
    }
    memset(t->data, 0, sizeof(sockaddr_un_pair));
    t->data_length = sizeof(sockaddr_un_pair);
    sup = (sockaddr_un_pair *) t->data;

    t->sock = socket(PF_UNIX, SOCK_STREAM, 0);
    if (t->sock < 0) {
        netsnmp_transport_free(t);
        return NULL;
    }

    t->flags = NETSNMP_TRANSPORT_FLAG_STREAM;

    if (local) {
        t->local = malloc(strlen(addr->sun_path));
        if (t->local == NULL) {
            netsnmp_transport_free(t);
            return NULL;
        }
        memcpy(t->local, addr->sun_path, strlen(addr->sun_path));
        t->local_length = strlen(addr->sun_path);

        /*
         * This session is inteneded as a server, so we must bind to the given
         * path (unlinking it first, to avoid errors).  
         */

        t->flags |= NETSNMP_TRANSPORT_FLAG_LISTEN;

        unlink(addr->sun_path);
        rc = bind(t->sock, (struct sockaddr *) addr, SUN_LEN(addr));
        if (rc != 0) {
            DEBUGMSGTL(("netsnmp_unix_transport",
                        "couldn't bind \"%s\", errno %d (%s)\n",
                        addr->sun_path, errno, strerror(errno)));
            netsnmp_unix_close(t);
            netsnmp_transport_free(t);
            return NULL;
        }

        /*
         * Save the address in the transport-specific data pointer for later
         * use by netsnmp_unix_close.
         */

        sup->server.sun_family = AF_UNIX;
        strcpy(sup->server.sun_path, addr->sun_path);
        sup->local = 1;

        /*
         * Now sit here and listen for connections to arrive.  
         */

        rc = listen(t->sock, NETSNMP_STREAM_QUEUE_LEN);
        if (rc != 0) {
            DEBUGMSGTL(("netsnmp_unix_transport",
                        "couldn't listen to \"%s\", errno %d (%s)\n",
                        addr->sun_path, errno, strerror(errno)));
            netsnmp_unix_close(t);
            netsnmp_transport_free(t);
        }

    } else {
        t->remote = malloc(strlen(addr->sun_path));
        if (t->remote == NULL) {
            netsnmp_transport_free(t);
            return NULL;
        }
        memcpy(t->remote, addr->sun_path, strlen(addr->sun_path));
        t->remote_length = strlen(addr->sun_path);

        rc = connect(t->sock, (struct sockaddr *) addr,
                     sizeof(struct sockaddr_un));
        if (rc != 0) {
            DEBUGMSGTL(("netsnmp_unix_transport",
                        "couldn't connect to \"%s\", errno %d (%s)\n",
                        addr->sun_path, errno, strerror(errno)));
            netsnmp_unix_close(t);
            netsnmp_transport_free(t);
            return NULL;
        }

        /*
         * Save the remote address in the transport-specific data pointer for
         * later use by netsnmp_unix_send.  
         */

        sup->server.sun_family = AF_UNIX;
        strcpy(sup->server.sun_path, addr->sun_path);
        sup->local = 0;
    }

    /*
     * Message size is not limited by this transport (hence msgMaxSize
     * is equal to the maximum legal size of an SNMP message).  
     */

    t->msgMaxSize = 0x7fffffff;
    t->f_recv     = netsnmp_unix_recv;
    t->f_send     = netsnmp_unix_send;
    t->f_close    = netsnmp_unix_close;
    t->f_accept   = netsnmp_unix_accept;
    t->f_fmtaddr  = netsnmp_unix_fmtaddr;

    return t;
}

netsnmp_transport *
netsnmp_unix_create_tstring(const char *string, int local)
{
    struct sockaddr_un addr;

    if ((string != NULL) && (strlen(string) < sizeof(addr.sun_path))) {
        addr.sun_family = AF_UNIX;
        memset(addr.sun_path, 0, sizeof(addr.sun_path));
        strncpy(addr.sun_path, string, sizeof(addr.sun_path) - 1);
        return netsnmp_unix_transport(&addr, local);
    } else {
        if (string != NULL) {
            snmp_log(LOG_ERR, "Path too long for Unix domain transport\n");
        }
        return NULL;
    }
}



netsnmp_transport *
netsnmp_unix_create_ostring(const u_char * o, size_t o_len, int local)
{
    struct sockaddr_un addr;

    if (o_len > 0 && o_len < (sizeof(addr.sun_path) - 1)) {
        addr.sun_family = AF_UNIX;
        memset(addr.sun_path, 0, sizeof(addr.sun_path));
        strncpy(addr.sun_path, o, o_len);
        return netsnmp_unix_transport(&addr, local);
    } else {
        if (o_len > 0) {
            snmp_log(LOG_ERR, "Path too long for Unix domain transport\n");
        }
    }
    return NULL;
}



void
netsnmp_unix_ctor(void)
{
    unixDomain.name = netsnmp_UnixDomain;
    unixDomain.name_length = sizeof(netsnmp_UnixDomain) / sizeof(oid);
    unixDomain.prefix = calloc(2, sizeof(char *));
    unixDomain.prefix[0] = "unix";

    unixDomain.f_create_from_tstring = netsnmp_unix_create_tstring;
    unixDomain.f_create_from_ostring = netsnmp_unix_create_ostring;

    netsnmp_tdomain_register(&unixDomain);
}