snmpudpdomain.c

snmp up 2

#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_NETINET_IN_H
#include <netinet/in.h>
#endif
#if HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#if HAVE_NETDB_H
#include <netdb.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/snmpUDPDomain.h>

#ifndef INADDR_NONE
#define INADDR_NONE	-1
#endif

static netsnmp_tdomain udpDomain;

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

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

    if (data != NULL && len == sizeof(struct sockaddr_in)) {
        to = (struct sockaddr_in *) data;
    } else if (t != NULL && t->data != NULL) {
        to = (struct sockaddr_in *) t->data;
    }
    if (to == NULL) {
        return strdup("UDP: unknown");
    } else {
	char tmp[64];

        /*
         * Here we just print the IP address of the peer for compatibility
         * purposes.  It would be nice if we could include the port number and
         * some indication of the domain (c.f. AAL5PVC).  
         */

        sprintf(tmp, "%s", inet_ntoa(to->sin_addr));
        return strdup(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_udp_recv(netsnmp_transport *t, void *buf, int size,
		 void **opaque, int *olength)
{
    int             rc = -1;
    socklen_t       fromlen = sizeof(struct sockaddr);
    struct sockaddr *from;

    if (t != NULL && t->sock >= 0) {
        from = (struct sockaddr *) malloc(sizeof(struct sockaddr_in));
        if (from == NULL) {
            *opaque = NULL;
            *olength = 0;
            return -1;
        } else {
            memset(from, 0, fromlen);
        }

	while (rc < 0) {
	    rc = recvfrom(t->sock, buf, size, 0, from, &fromlen);
	    if (rc < 0 && errno != EINTR) {
		break;
	    }
	}

        if (rc >= 0) {
            char *string = netsnmp_udp_fmtaddr(NULL, from, fromlen);
            DEBUGMSGTL(("netsnmp_udp",
			"recvfrom fd %d got %d bytes (from %s)\n",
			t->sock, rc, string));
            free(string);
        } else {
            DEBUGMSGTL(("netsnmp_udp", "recvfrom fd %d err %d (\"%s\")\n",
                        t->sock, errno, strerror(errno)));
        }
        *opaque = (void *)from;
        *olength = sizeof(struct sockaddr_in);
    }
    return rc;
}



static int
netsnmp_udp_send(netsnmp_transport *t, void *buf, int size,
		 void **opaque, int *olength)
{
    int rc = -1;
	int i;
	char *aa;
    struct sockaddr *to = NULL;

    if (opaque != NULL && *opaque != NULL &&
        *olength == sizeof(struct sockaddr_in)) {
        to = (struct sockaddr *) (*opaque);
    } else if (t != NULL && t->data != NULL &&
               t->data_length == sizeof(struct sockaddr_in)) {
        to = (struct sockaddr *) (t->data);
    }


    if (to != NULL && t != NULL && t->sock >= 0) {
        char *string = netsnmp_udp_fmtaddr(NULL, (void *) to,
					sizeof(struct sockaddr_in));
        DEBUGMSGTL(("netsnmp_udp", "send %d bytes from %p to %s on fd %d\n",
                    size, buf, string, t->sock));
        free(string);
	while (rc < 0) {
	    rc = sendto(t->sock, buf, size, 0, to, sizeof(struct sockaddr));
	    if (rc < 0 && errno != EINTR) {
		break;
	    }
	}
    }
    return rc;
}



static int
netsnmp_udp_close(netsnmp_transport *t)
{
    int rc = -1;
    if (t->sock >= 0) {
#ifndef HAVE_CLOSESOCKET
        rc = close(t->sock);
#else
        rc = closesocket(t->sock);
#endif
        t->sock = -1;
    }
    return rc;
}



/*
 * Open a UDP-based 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.  
 */

netsnmp_transport *
netsnmp_udp_transport(struct sockaddr_in *addr, int local)
{
    netsnmp_transport *t = NULL;
    int             rc = 0, udpbuf = (1 << 17);
    char           *string = NULL;

    if (addr == NULL || addr->sin_family != AF_INET) {
        return NULL;
    }

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

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

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

    t->domain = netsnmpUDPDomain;
    t->domain_length = netsnmpUDPDomain_len;

    t->sock = socket(PF_INET, SOCK_DGRAM, 0);
    if (t->sock < 0) {
        netsnmp_transport_free(t);
        return NULL;
    }
#ifdef  SO_BSDCOMPAT
    /*
     * Patch for Linux.  Without this, UDP packets that fail get an ICMP
     * response.  Linux turns the failed ICMP response into an error message
     * and return value, unlike all other OS's.  
     */
    {
        int             one = 1;
        setsockopt(t->sock, SOL_SOCKET, SO_BSDCOMPAT, (void *) &one,
                   sizeof(one));
    }
#endif                          /*SO_BSDCOMPAT */
    /*
     * SO_REUSEADDR will allow multiple apps to open the same port at
     * the same time. Only the last one to open the socket will get
     * data. Obviously, for an agent, this is a bad thing. There should
     * only be one listener.
     */
#ifdef ALLOW_PORT_HIJACKING
#ifdef  SO_REUSEADDR
    /*
     * Allow the same port to be specified multiple times without failing.
     *    (useful for a listener)
     */
    {
        int             one = 1;
        setsockopt(t->sock, SOL_SOCKET, SO_REUSEADDR, (void *) &one,
                   sizeof(one));
    }
#endif                          /*SO_REUSEADDR */
#endif
    /*
     * Try to set the send and receive buffers to a reasonably large value, so
     * that we can send and receive big PDUs (defaults to 8192 bytes (!) on
     * Solaris, for instance).  Don't worry too much about errors -- just
     * plough on regardless.  
     */

#ifdef  SO_SNDBUF
    if (setsockopt
        (t->sock, SOL_SOCKET, SO_SNDBUF, (void *) &udpbuf,
         sizeof(int)) != 0) {
        DEBUGMSGTL(("netsnmp_udp", "couldn't set SO_SNDBUF to %d bytes: %s\n",
                    udpbuf, strerror(errno)));
    }
#endif                          /*SO_SNDBUF */

#ifdef  SO_RCVBUF
    if (setsockopt
        (t->sock, SOL_SOCKET, SO_RCVBUF, (void *) &udpbuf,
         sizeof(int)) != 0) {
        DEBUGMSGTL(("netsnmp_udp", "couldn't set SO_RCVBUF to %d bytes: %s\n",
                    udpbuf, strerror(errno)));
    }
#endif                          /*SO_RCVBUF */

    if (local) {
        /*
         * This session is inteneded as a server, so we must bind on to the
         * given IP address, which may include an interface address, or could
         * be INADDR_ANY, but certainly includes a port number.
         */

        t->local = malloc(6);
        if (t->local == NULL) {
            netsnmp_transport_free(t);
            return NULL;
        }
        memcpy(t->local, (u_char *) & (addr->sin_addr.s_addr), 4);
        t->local[4] = (htons(addr->sin_port) & 0xff00) >> 8;
        t->local[5] = (htons(addr->sin_port) & 0x00ff) >> 0;
        t->local_length = 6;

        rc = bind(t->sock, (struct sockaddr *) addr,
                  sizeof(struct sockaddr));
        if (rc != 0) {
            netsnmp_udp_close(t);
            netsnmp_transport_free(t);
            return NULL;
        }
        t->data = NULL;
        t->data_length = 0;
    } else {
        /*
         * This is a client session.  Save the address in the
         * transport-specific data pointer for later use by netsnmp_udp_send.
         */

        t->data = malloc(sizeof(struct sockaddr_in));
        t->remote = malloc(6);
        if (t->data == NULL || t->remote == NULL) {
            netsnmp_transport_free(t);
            return NULL;
        }
        memcpy(t->remote, (u_char *) & (addr->sin_addr.s_addr), 4);
        t->remote[4] = (htons(addr->sin_port) & 0xff00) >> 8;
        t->remote[5] = (htons(addr->sin_port) & 0x00ff) >> 0;
        t->remote_length = 6;
        memcpy(t->data, addr, sizeof(struct sockaddr_in));
        t->data_length = sizeof(struct sockaddr_in);
    }

    /*
     * 16-bit length field, 8 byte UDP header, 20 byte IPv4 header  
     */

    t->msgMaxSize = 0xffff - 8 - 20;
    t->f_recv     = netsnmp_udp_recv;
    t->f_send     = netsnmp_udp_send;
    t->f_close    = netsnmp_udp_close;
    t->f_accept   = NULL;
    t->f_fmtaddr  = netsnmp_udp_fmtaddr;

    return t;
}



int
netsnmp_sockaddr_in(struct sockaddr_in *addr,
                    const char *inpeername, int remote_port)
{
    char           *cp = NULL, *peername = NULL;

    if (addr == NULL) {
        return 0;
    }
    memset(addr, 0, sizeof(struct sockaddr_in));

    DEBUGMSGTL(("netsnmp_sockaddr_in", "addr %p, peername \"%s\"\n",
                addr, inpeername ? inpeername : "[NIL]"));

    addr->sin_addr.s_addr = htonl(INADDR_ANY);
    addr->sin_family = AF_INET;
    if (remote_port > 0) {
        addr->sin_port = htons(remote_port);
    } else if (netsnmp_ds_get_int(NETSNMP_DS_LIBRARY_ID, 
				  NETSNMP_DS_LIB_DEFAULT_PORT) > 0) {
        addr->sin_port = htons(netsnmp_ds_get_int(NETSNMP_DS_LIBRARY_ID, 
						 NETSNMP_DS_LIB_DEFAULT_PORT));
    } else {
        addr->sin_port = htons(SNMP_PORT);
    }

    if (inpeername != NULL) {
        /*
         * Duplicate the peername because we might want to mank around with
         * it.  
         */

        peername = strdup(inpeername);
        if (peername == NULL) {
            return 0;
        }

        /*
         * Try and extract an appended port number.  
         */
        cp = strchr(peername, ':');
        if (cp != NULL) {
            *cp = '\0';
            cp++;
            if (atoi(cp) != 0) {
                DEBUGMSGTL(("netsnmp_sockaddr_in",
                            "port number suffix :%d\n", atoi(cp)));
                addr->sin_port = htons(atoi(cp));
            }
        }

        for (cp = peername; *cp && isdigit((int) *cp); cp++);