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/*
 * Simple Network Management Protocol (RFC 1067).
 *
 */
/***********************************************************
	Copyright 1988, 1989 by Carnegie Mellon University

                      All Rights Reserved

Permission to use, copy, modify, and distribute this software and its 
documentation for any purpose and without fee is hereby granted, 
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in 
supporting documentation, and that the name of CMU not be
used in advertising or publicity pertaining to distribution of the
software without specific, written prior permission.  

CMU DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
CMU BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
SOFTWARE.
******************************************************************/

#ifdef KINETICS
#include "gw.h"
#include "ab.h"
#include "inet.h"
#include "fp4/cmdmacro.h"
#include "fp4/pbuf.h"
#include "glob.h"
#endif

#if (defined(unix) && !defined(KINETICS))
#include <sys/types.h>
#include <netinet/in.h>
#ifndef NULL
#define NULL 0
#endif
#endif

#include "snmp.h"
#include "snmp_impl.h"
#include "asn1.h"

#include "mib.h"
#include "snmp_vars.h"

void	snmp_input();
void	snmp_trap();
int	create_identical();
int	parse_var_op_list();
int	snmp_access();

char	version_descr[];
oid	version_id[];
int	version_id_len;

struct pbuf *definitelyGetBuf();

#define NUM_COMMUNITIES	5
char	*communities[NUM_COMMUNITIES] = {
    "public", 
    "proxy",
    "private",
    "regional",
    "core"
};

/* these can't be global in a multi-process router */
    u_char	sid[SID_MAX_LEN + 1];
    int		sidlen;
    u_char	*packet_end;
    int		community;


#ifdef KINETICS
void
snmp_input(p)
    struct pbuf *p;
{
    struct ip	    *ip = (struct ip *)p->p_off;
    int		    hlen = (int)ip->ip_hl << 2;
    register struct udp	    *udp;
    register u_char *data;  /* pointer to the rest of the unread data */
    int		    length; /* bytes of data left in msg after the "data" pointer */
    struct pbuf	    *out_packet;
    register u_char *out_data;
    int		    out_length;
    u_short	    udp_src;
    extern struct mib_udp   mib_udp;

    
    udp = (struct udp *)(p->p_off + hlen);
    if (ntohs(ip->ip_len) - hlen < sizeof(struct udp) ||    /* IP length < minimum UDP packet */
	    ntohs(udp->length) > ntohs(ip->ip_len) - hlen){ /* UDP length > IP data */
	ERROR("dropped packet with bad length");    /* delete me */
	return; /* drop packet */
    }
    data = (u_char *)udp + sizeof(struct udp);
    length = ntohs(udp->length) - sizeof(struct udp);

    out_packet = definitelyGetBuf(); /* drop packets off input queue if necessary */
    out_data = (u_char *)(out_packet->p_off + sizeof (struct ip) + sizeof (struct udp));
    out_length = MAXDATA - sizeof(struct ip) - sizeof (struct udp);

K_LEDON();
    if (!snmp_parse(data, length, out_data, out_length, (u_long)ip->ip_src)){
	K_PFREE(out_packet);
K_LEDOFF();
	return;
    }
K_LEDOFF();
    out_packet->p_len = packet_end - (u_char *)out_packet->p_off;
    setiphdr(out_packet, ip->ip_src);	/* address to source of request packet (ntohl ??? ) */
    udp_src = ntohs(udp->src);
    udp = (struct udp *)(out_packet->p_off + sizeof (struct ip));
    udp->src = htons(SNMP_PORT);
    udp->dst = htons(udp_src);
    udp->length = out_packet->p_len - sizeof(struct ip);
    udp->checksum = 0;	/* this should be computed */

    mib_udp.udpOutDatagrams++;
    routeip(out_packet, 0, 0);
}


void
snmp_trap(destAddr, trapType, specificType)
    u_long  destAddr;
    int	    trapType;
    int	    specificType;
{
    struct pbuf	    *out_packet;
    register u_char *out_data;
    register struct udp	    *udp;
    int		    out_length;
    static oid	    sysDescrOid[] = {1, 3, 6, 1, 2, 1, 1, 1, 0};
    
    out_packet = definitelyGetBuf(); /* drop packets off input queue if necessary */
    out_data = (u_char *)(out_packet->p_off + sizeof (struct ip) + sizeof (struct udp));
    out_length = MAXDATA - sizeof(struct ip) - sizeof (struct udp);

K_LEDON();
    out_packet->p_len = snmp_build_trap(out_data, out_length, version_id, version_id_len,
	conf.ipaddr, trapType, specificType, TICKS2MS(tickclock)/10, sysDescrOid, sizeof(sysDescrOid)/sizeof(oid),
	ASN_OCTET_STR, strlen(version_descr), (u_char *)version_descr);
    if (out_packet->p_len == 0){
	K_PFREE(out_packet);
K_LEDOFF();
	return;
    }
K_LEDOFF();
    out_packet->p_len += sizeof(struct ip) + sizeof(struct udp);
    setiphdr(out_packet, destAddr);	/* address to source of request packet (ntohl ??? ) */
    udp = (struct udp *)(out_packet->p_off + sizeof (struct ip));
    udp->src = htons(SNMP_PORT);
    udp->dst = htons(SNMP_TRAP_PORT);
    udp->length = out_packet->p_len - sizeof(struct ip);
    udp->checksum = 0;	/* this should be computed */

    mib_udp.udpOutDatagrams++;
    routeip(out_packet, 0, 0);
}
#endif

int
snmp_parse(data, length, out_data, out_length, sourceip)
    register u_char	*data;
    int			length;
    register u_char	*out_data;
    int			out_length;
    u_long		sourceip;	/* possibly for authentication */
{
    u_char	    msg_type, type;
    long	    zero = 0;
    long	    reqid, errstat, errindex;
    register u_char *out_auth, *out_header, *out_reqid;
    u_char	    *startData = data;
    int		    startLength = length;
    long	    version;
    int		    header_shift, auth_shift;

    sidlen = SID_MAX_LEN;
    data = snmp_auth_parse(data, &length, sid, &sidlen, &version); /* authenticates message and returns length if valid */
    if (data == NULL){
	ERROR("bad authentication");
	/* send auth fail trap */
	return 0;
    }
    if (version != SNMP_VERSION_1){
	ERROR("wrong version");
	return NULL;
    }
    community = get_community(sid);
    if (community == -1)
	return NULL;
    data = asn_parse_header(data, &length, &msg_type);
    if (data == NULL){
	ERROR("bad header");
	return 0;
    }
    if (msg_type != GET_REQ_MSG && msg_type != GETNEXT_REQ_MSG && msg_type != SET_REQ_MSG){
	return 0;
    }
    data = asn_parse_int(data, &length, &type, (u_long *)&reqid, sizeof(reqid));
    if (data == NULL){
	ERROR("bad parse of reqid");
	return 0;
    }
    data = asn_parse_int(data, &length, &type, (u_long *)&errstat, sizeof(errstat));
    if (data == NULL){
	ERROR("bad parse of errstat");
	return 0;
    }
    data = asn_parse_int(data, &length, &type, (u_long *)&errindex, sizeof(errindex));
    if (data == NULL){
	ERROR("bad parse of errindex");
	return 0;
    }
    /*
     * Now start cobbling together what is known about the output packet.
     * The final lengths are not known now, so they will have to be recomputed
     * later.
     */
    out_auth = out_data;
    out_header = snmp_auth_build(out_auth, &out_length, sid, &sidlen, &zero, 0);
    if (out_header == NULL){
	ERROR("snmp_auth_build failed");
	return 0;
    }
    out_reqid = asn_build_header(out_header, &out_length, (u_char)GET_RSP_MSG, 0);
    if (out_reqid == NULL){
	ERROR("");
	return 0;
    }

    type = (u_char)(ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_INTEGER);
    /* return identical request id */
    out_data = asn_build_int(out_reqid, &out_length, type, (u_char *)&reqid, sizeof(reqid));
    if (out_data == NULL){
	ERROR("build reqid failed");
	return 0;
    }

    /* assume that error status will be zero */
    out_data = asn_build_int(out_data, &out_length, type, (u_char *)&zero, sizeof(zero));
    if (out_data == NULL){
	ERROR("build errstat failed");
	return 0;
    }

    /* assume that error index will be zero */
    out_data = asn_build_int(out_data, &out_length, type, (u_char *)&zero, sizeof(zero));
    if (out_data == NULL){
	ERROR("build errindex failed");
	return 0;
    }

    errstat = parse_var_op_list(data, length, out_data, out_length, msg_type, &errindex, 0);
    if (msg_type == SET_REQ_MSG && errstat == SNMP_ERR_NOERROR){
	/*
	 * SETS require 2 passes through the var_op_list.  The first pass verifies that
	 * all types, lengths, and values are valid, and the second does the set.  Then
	 * the identical GET RESPONSE packet is returned.
	 */
	errstat = parse_var_op_list(data, length, out_data, out_length, msg_type, &errindex, 1);
	if (create_identical(startData, out_auth, startLength, 0L, 0L))
	    return 1;
	return 0;
    }
    switch((short)errstat){
	case SNMP_ERR_NOERROR:
	    /*
	     * Because of the assumption above that header lengths would be encoded
	     * in one byte, things need to be fixed, now that the actual lengths are known.
	     */
	    header_shift = 0;
	    out_length = packet_end - out_reqid;
	    if (out_length >= 0x80){
		header_shift++;
		if (out_length > 0xFF)
		    header_shift++;
	    }
	    auth_shift = 0;
	    out_length = (packet_end - out_auth) - 2 + header_shift;
	    if (out_length >= 0x80){
		auth_shift++;
		if (out_length > 0xFF)
		    auth_shift++;
	    }
	    if (auth_shift + header_shift){
		/*
		 * Shift packet (from request id to end of packet) by the sum of the
		 * necessary shift counts.
		 */
		shift_array(out_reqid, packet_end - out_reqid, auth_shift + header_shift);
		/* Now adjust pointers into the packet */
		packet_end += auth_shift + header_shift;
		out_reqid += auth_shift + header_shift;
		out_header += auth_shift;
	    }
	    
	    /* re-encode the headers with the real lengths */
	    out_data = out_header;
	    out_length = packet_end - out_reqid;
	    out_data = asn_build_header(out_data, &out_length, GET_RSP_MSG, out_length);
	    if (out_data != out_reqid){
		ERROR("internal error: header");
		return 0;
	    }

	    out_data = out_auth;
	    out_length = packet_end - out_auth;
	    out_data = snmp_auth_build(out_data, &out_length, sid, &sidlen, &zero, packet_end - out_header);
	    if (out_data != out_header){
		ERROR("internal error");
		return 0;
	    }
	    break;
	case SNMP_ERR_NOSUCHNAME:
	case SNMP_ERR_TOOBIG:
	case SNMP_ERR_BADVALUE:
	case SNMP_ERR_READONLY:
	case SNMP_ERR_GENERR:
	    if (create_identical(startData, out_auth, startLength, errstat, errindex))
		break;
	    return 0;
	default:
	    return 0;
    }
    return 1;
}

/*
 * Parse_var_op_list goes through the list of variables and retrieves each one,
 * placing it's value in the output packet.  If doSet is non-zero, the variable is set
 * with the value in the packet.  If any error occurs, an error code is returned.
 */
int
parse_var_op_list(data, length, out_data, out_length, msgtype, index, doSet)
    register u_char	*data;
    int			length;
    register u_char	*out_data;
    int			out_length;
    u_char		msgtype;
    register long	*index;
    int			doSet;
{
    u_char  type;
    oid	    var_name[MAX_NAME_LEN];
    int	    var_name_len, var_val_len;
    u_char  var_val_type, *var_val, statType;
    register u_char *statP;
    int	    statLen;
    u_short acl;
    int	    rw, exact;
    int	    access_method;
    u_char  *headerP, *var_list_start;
    int	    dummyLen;
    int	    header_shift;

    if (msgtype == SET_REQ_MSG)
	rw = WRITE;
    else
	rw = READ;
    if (msgtype == GETNEXT_REQ_MSG)
	exact = FALSE;
    else
	exact = TRUE;
    data = asn_parse_header(data, &length, &type);
    if (data == NULL){
	ERROR("not enough space for varlist");
	return PARSE_ERROR;
    }
    if (type != (u_char)(ASN_SEQUENCE | ASN_CONSTRUCTOR)){
	ERROR("wrong type");
	return PARSE_ERROR;
    }
    headerP = out_data;
    out_data = asn_build_header(out_data, &out_length, (u_char)(ASN_SEQUENCE | ASN_CONSTRUCTOR), 0);
    if (out_data == NULL){
    	ERROR("not enough space in output packet");
	return BUILD_ERROR;
    }
    var_list_start = out_data;

    *index = 1;
    while((int)length > 0){
	/* parse the name, value pair */
	var_name_len = MAX_NAME_LEN;
	data = snmp_parse_var_op(data, var_name, &var_name_len, &var_val_type, &var_val_len, &var_val, (int *)&length);
	if (data == NULL)
	    return PARSE_ERROR;
	/* now attempt to retrieve the variable on the local entity */
	statP = getStatPtr(var_name, &var_name_len, &statType, &statLen, &acl, exact, &access_method);
	if (statP == NULL)
	    return SNMP_ERR_NOSUCHNAME;
	/* Check if this user has access rights to this variable */
	if (!snmp_access(acl, community, rw)){
	    ERROR("authentication failed");
	    return SNMP_ERR_NOSUCHNAME;	/* bogus */
	    /* send_trap(); */
	}
	if (msgtype == SET_REQ_MSG){
	    /* see if the type and value is consistent with this entities variable */
	    if (!goodValue(var_val_type, var_val_len, statType, statLen)){
		return SNMP_ERR_BADVALUE;
	    }
	    /* actually do the set if necessary */
	    if (doSet)
		setVariable(var_val, var_val_type, var_val_len, statP, statLen);
	}
	/* retrieve the value of the variable and place it into the outgoing packet */
	out_data = snmp_build_var_op(out_data, var_name, &var_name_len, statType, statLen, statP, &out_length);
	if (out_data == NULL){
	    return SNMP_ERR_TOOBIG;
	}

	(*index)++;
    }
    packet_end = out_data;  /* save a pointer to the end of the packet */

    /*
     * Because of the assumption above that header lengths would be encoded
     * in one byte, things need to be fixed, now that the actual lengths are known.
     */
    header_shift = 0;
    out_length = packet_end - var_list_start;
    if (out_length >= 0x80){
	header_shift++;
	if (out_length > 0xFF)
	    header_shift++;
    }
    if (header_shift){
	shift_array(var_list_start, packet_end - var_list_start, header_shift);
	packet_end += header_shift;
	var_list_start += header_shift;
    }

    /* Now rebuild header with the actual lengths */
    dummyLen = packet_end - var_list_start;
    if (asn_build_header(headerP, &dummyLen, (u_char)(ASN_SEQUENCE | ASN_CONSTRUCTOR), dummyLen) == NULL){
	return SNMP_ERR_TOOBIG;	/* bogus error ???? */
    }
    *index = 0;
    return SNMP_ERR_NOERROR;
}

/*
 * create a packet identical to the input packet, except for the error status
 * and the error index which are set according to the input variables.
 * Returns 1 upon success and 0 upon failure.
 */
int
create_identical(snmp_in, snmp_out, snmp_length, errstat, errindex)
    u_char	    *snmp_in;
    u_char	    *snmp_out;
    int		    snmp_length;
    long	    errstat, errindex;
{
    register u_char *data;
    u_char	    type;
    u_long	    dummy;
    int		    length, headerLength;
    register u_char *headerPtr, *reqidPtr, *errstatPtr, *errindexPtr, *varListPtr;

    bcopy((char *)snmp_in, (char *)snmp_out, snmp_length);
    length = snmp_length;
    headerPtr = snmp_auth_parse(snmp_out, &length, sid, &sidlen, (long *)&dummy);
    if (headerPtr == NULL)
	return 0;
    reqidPtr = asn_parse_header(headerPtr, &length, (u_char *)&dummy);
    if (reqidPtr == NULL)
	return 0;
    headerLength = length;
    errstatPtr = asn_parse_int(reqidPtr, &length, &type, &dummy, sizeof dummy);	/* request id */
    if (errstatPtr == NULL)
	return 0;
    errindexPtr = asn_parse_int(errstatPtr, &length, &type, &dummy, sizeof dummy);	/* error status */
    if (errindexPtr == NULL)
	return 0;
    varListPtr = asn_parse_int(errindexPtr, &length, &type, &dummy, sizeof dummy);	/* error index */
    if (varListPtr == NULL)
	return 0;

    data = asn_build_header(headerPtr, &headerLength, GET_RSP_MSG, headerLength);
    if (data != reqidPtr)
	return 0;
    length = snmp_length;
    type = (u_char)(ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_INTEGER);
    data = asn_build_int(errstatPtr, &length, type, (u_char *)&errstat, sizeof errstat);
    if (data != errindexPtr)
	return 0;
    data = asn_build_int(errindexPtr, &length, type, (u_char *)&errindex, sizeof errindex);
    if (data != varListPtr)
	return 0;
    packet_end = snmp_out + snmp_length;
    return 1;
}

#ifdef KINETICS
struct pbuf *
definitelyGetBuf(){
    register struct pbuf *p;

    K_PGET(PT_DATA, p);
    while(p == 0){
#ifdef notdef
	if (pq->pq_head != NULL){
	    K_PDEQ(SPLIMP, pq, p);
	    if (p) K_PFREE(p);
	} else if (sendq->pq_head != NULL){
	    K_PDEQ(SPLIMP, sendq, p);
	    if (p) K_PFREE(p);
	}
#endif
	K_PGET(PT_DATA, p);
    }
    return p;
}
#endif

int
snmp_access(acl, community, rw)
    u_short 	acl;
    int		community;
    int		rw;
{
    /*
     * Each group has 2 bits, the more significant one is for read access,
     * the less significant one is for write access.
     */

    community <<= 1;	/* multiply by two two shift two bits at a time */
    if (rw == READ){
	return (acl & (2 << community));    /* return the correct bit */
    } else {
	return (acl & (1 << community));
    }
}

int
get_community(sessionid)
    u_char	*sessionid;
{
    int	count;

    for(count = 0; count < NUM_COMMUNITIES; count++){
	if (!strcmp(communities[count], sessionid))
	    break;
    }
    if (count == NUM_COMMUNITIES)
	return -1;
    return count;
}

int
goodValue(inType, inLen, actualType, actualLen)
    u_char	inType, actualType;
    int		inLen, actualLen;
{
    int	type;

    if (inLen > actualLen)
	return FALSE;
    /* convert intype to internal representation */
    type = inType == ASN_INTEGER ? INTEGER : inType == ASN_OCTET_STR ? STRING : inType == ASN_OBJECT_ID ? OBJID : NULLOBJ;
    return (type == actualType);
}

setVariable(var_val, var_val_type, var_val_len, statP, statLen)
    u_char  *var_val;
    u_char  var_val_type;
    int	    var_val_len;
    u_char  *statP;
    int	    statLen;
{
    int	    buffersize = 1000;

    switch(var_val_type){
	case ASN_INTEGER:
	case COUNTER:
	case GAUGE:
	case TIMETICKS:
	    asn_parse_int(var_val, &buffersize, &var_val_type, (u_long *)statP, statLen);
	    break;
	case ASN_OCTET_STR:
	case IPADDRESS:
	case OPAQUE:
	    asn_parse_string(var_val, &buffersize, &var_val_type, statP, &statLen);
	    break;
	case ASN_OBJECT_ID:
	    asn_parse_objid(var_val, &buffersize, &var_val_type, statP, &statLen);
	    break;
    }
}


shift_array(begin, length, shift_amount)
    u_char	    *begin;
    register int    length;
    int		    shift_amount;
{
    register u_char	*old, *new;

    if (shift_amount >= 0){
	old = begin + length - 1;
	new = old + shift_amount;

	while(length--)
	    *new-- = *old--;
    } else {
	old = begin;
	new = begin + shift_amount;

	while(length--)
	    *new++ = *old++;
    }
}
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