asn1.c

snmp up 2

}


/*
 * asn_build_unsigned_int - builds an ASN object containing an integer.
 *  On entry, datalength is input as the number of valid bytes following
 *   "data".  On exit, it is returned as the number of valid bytes
 *   following the end of this object.
 *
 *  Returns a pointer to the first byte past the end
 *   of this object (i.e. the start of the next object).
 *  Returns NULL on any error.
 
 u_char * asn_build_unsigned_int(
 u_char     *data         IN - pointer to start of output buffer
 int        *datalength   IN/OUT - number of valid bytes left in buffer
 u_char      type         IN  - asn type of object
 u_long     *intp         IN - pointer to start of long integer
 int         intsize      IN - size of input buffer
 */
u_char         *
asn_build_unsigned_int(u_char * data,
                       size_t * datalength,
                       u_char type, u_long * intp, size_t intsize)
{
    /*
     * ASN.1 integer ::= 0x02 asnlength byte {byte}*
     */
    static const char *errpre = "build uint";
    register u_long integer;
    register u_long mask;
    int             add_null_byte = 0;
#ifndef SNMP_NO_DEBUGGING
    u_char         *initdatap = data;
#endif

    if (intsize != sizeof(long)) {
        _asn_size_err(errpre, intsize, sizeof(long));
        return NULL;
    }
    integer = *intp;
    mask = ((u_long) 0xFF) << (8 * (sizeof(long) - 1));
    /*
     * mask is 0xFF000000 on a big-endian machine 
     */
    if ((u_char) ((integer & mask) >> (8 * (sizeof(long) - 1))) & 0x80) {
        /*
         * if MSB is set 
         */
        add_null_byte = 1;
        intsize++;
    } else {
        /*
         * Truncate "unnecessary" bytes off of the most significant end of this 2's complement integer.
         * There should be no sequence of 9 consecutive 1's or 0's at the most significant end of the
         * integer.
         */
        mask = ((u_long) 0x1FF) << ((8 * (sizeof(long) - 1)) - 1);
        /*
         * mask is 0xFF800000 on a big-endian machine 
         */
        while ((((integer & mask) == 0) || ((integer & mask) == mask))
               && intsize > 1) {
            intsize--;
            integer <<= 8;
        }
    }
    data = asn_build_header(data, datalength, type, intsize);
    if (_asn_build_header_check(errpre, data, *datalength, intsize))
        return NULL;

    *datalength -= intsize;
    if (add_null_byte == 1) {
        *data++ = '\0';
        intsize--;
    }
    mask = ((u_long) 0xFF) << (8 * (sizeof(long) - 1));
    /*
     * mask is 0xFF000000 on a big-endian machine 
     */
    while (intsize--) {
        *data++ = (u_char) ((integer & mask) >> (8 * (sizeof(long) - 1)));
        integer <<= 8;
    }
    DEBUGDUMPSETUP("send", initdatap, data - initdatap);
    DEBUGMSG(("dumpv_send", "  UInteger:\t%ld (0x%.2X)\n", *intp, *intp));
    return data;
}


/*
 * asn_parse_string - pulls an octet string out of an ASN octet string type.
 *  On entry, datalength is input as the number of valid bytes following
 *   "data".  On exit, it is returned as the number of valid bytes
 *   following the beginning of the next object.
 *
 *  "string" is filled with the octet string.
 *
 *  Returns a pointer to the first byte past the end
 *   of this object (i.e. the start of the next object).
 *  Returns NULL on any error.
 *
 * u_char * asn_parse_string(
 *     u_char     *data         IN - pointer to start of object
 *     int        *datalength   IN/OUT - number of valid bytes left in buffer
 *     u_char     *type         OUT - asn type of object
 *     u_char     *string       IN/OUT - pointer to start of output buffer
 *     int        *strlength    IN/OUT - size of output buffer
 *
 *
 * ASN.1 octet string   ::=      primstring | cmpdstring
 * primstring           ::= 0x04 asnlength byte {byte}*
 * cmpdstring           ::= 0x24 asnlength string {string}*
 */
u_char         *
asn_parse_string(u_char * data,
                 size_t * datalength,
                 u_char * type, u_char * string, size_t * strlength)
{
    static const char *errpre = "parse string";
    u_char         *bufp = data;
    u_long          asn_length;

    *type = *bufp++;
    bufp = asn_parse_length(bufp, &asn_length);
    if (_asn_parse_length_check
        (errpre, bufp, data, asn_length, *datalength)) {
        return NULL;
    }

    if ((int) asn_length > *strlength) {
        _asn_length_err(errpre, (size_t) asn_length, *strlength);
        return NULL;
    }

    DEBUGDUMPSETUP("recv", data, bufp - data + asn_length);

    memmove(string, bufp, asn_length);
    if (*strlength > (int) asn_length)
        string[asn_length] = 0;
    *strlength = (int) asn_length;
    *datalength -= (int) asn_length + (bufp - data);

    DEBUGIF("dumpv_recv") {
        u_char         *buf = (u_char *) malloc(1 + asn_length);
        size_t          l = (buf != NULL) ? (1 + asn_length) : 0, ol = 0;

        if (sprint_realloc_asciistring
            (&buf, &l, &ol, 1, string, asn_length)) {
            DEBUGMSG(("dumpv_recv", "  String:\t%s\n", buf));
        } else {
            if (buf == NULL) {
                DEBUGMSG(("dumpv_recv", "  String:\t[TRUNCATED]\n"));
            } else {
                DEBUGMSG(("dumpv_recv", "  String:\t%s [TRUNCATED]\n",
                          buf));
            }
        }
        if (buf != NULL) {
            free(buf);
        }
    }

    return bufp + asn_length;
}


/*
 * asn_build_string - Builds an ASN octet string object containing the input string.
 *  On entry, datalength is input as the number of valid bytes following
 *   "data".  On exit, it is returned as the number of valid bytes
 *   following the beginning of the next object.
 *
 *  Returns a pointer to the first byte past the end
 *   of this object (i.e. the start of the next object).
 *  Returns NULL on any error.
 
 u_char * asn_build_string(
 u_char     *data         IN - pointer to start of object
 int        *datalength   IN/OUT - number of valid bytes left in buffer
 u_char      type         IN - asn type of object
 u_char     *string       IN - pointer to start of input buffer
 int         strlength    IN - size of input buffer
 */
u_char         *
asn_build_string(u_char * data,
                 size_t * datalength,
                 u_char type, const u_char * string, size_t strlength)
{
    /*
     * ASN.1 octet string ::= primstring | cmpdstring
     * primstring ::= 0x04 asnlength byte {byte}*
     * cmpdstring ::= 0x24 asnlength string {string}*
     * This code will never send a compound string.
     */
#ifndef SNMP_NO_DEBUGGING
    u_char         *initdatap = data;
#endif
    data = asn_build_header(data, datalength, type, strlength);
    if (_asn_build_header_check
        ("build string", data, *datalength, strlength))
        return NULL;

    if (strlength) {
        if (string == NULL) {
            memset(data, 0, strlength);
        } else {
            memmove(data, string, strlength);
        }
    }
    *datalength -= strlength;
    DEBUGDUMPSETUP("send", initdatap, data - initdatap + strlength);
    DEBUGIF("dumpv_send") {
        u_char         *buf = (u_char *) malloc(1 + strlength);
        size_t          l = (buf != NULL) ? (1 + strlength) : 0, ol = 0;

        if (sprint_realloc_asciistring
            (&buf, &l, &ol, 1, string, strlength)) {
            DEBUGMSG(("dumpv_send", "  String:\t%s\n", buf));
        } else {
            if (buf == NULL) {
                DEBUGMSG(("dumpv_send", "  String:\t[TRUNCATED]\n"));
            } else {
                DEBUGMSG(("dumpv_send", "  String:\t%s [TRUNCATED]\n",
                          buf));
            }
        }
        if (buf != NULL) {
            free(buf);
        }
    }
    return data + strlength;
}



/*
 * asn_parse_header - interprets the ID and length of the current object.
 *  On entry, datalength is input as the number of valid bytes following
 *   "data".  On exit, it is returned as the number of valid bytes
 *   in this object following the id and length.
 *
 *  Returns a pointer to the first byte of the contents of this object.
 *  Returns NULL on any error.
 
 u_char * asn_parse_header(
 u_char     *data         IN - pointer to start of object
 int        *datalength   IN/OUT - number of valid bytes left in buffer
 u_char     *type         OUT - asn type of object
 */
u_char         *
asn_parse_header(u_char * data, size_t * datalength, u_char * type)
{
    register u_char *bufp;
    u_long          asn_length;

    if (!data || !datalength || !type) {
        ERROR_MSG("parse header: NULL pointer");
        return NULL;
    }
    bufp = data;
    /*
     * this only works on data types < 30, i.e. no extension octets 
     */
    if (IS_EXTENSION_ID(*bufp)) {
        ERROR_MSG("can't process ID >= 30");
        return NULL;
    }
    *type = *bufp;
    bufp = asn_parse_length(bufp + 1, &asn_length);

    if (_asn_parse_length_check
        ("parse header", bufp, data, asn_length, *datalength))
        return NULL;

#ifdef DUMP_PRINT_HEADERS
    DEBUGDUMPSETUP("recv", data, (bufp - data));
    DEBUGMSG(("dumpv_recv", "  Header: 0x%.2X, len = %d (0x%X)\n", *data,
              asn_length, asn_length));
#else
    /*
     * DEBUGMSGHEXTLI(("recv",data,(bufp-data)));
     * DEBUGMSG(("dumpH_recv","\n"));
     */
#endif

#ifdef OPAQUE_SPECIAL_TYPES

    if ((*type == ASN_OPAQUE) && (*bufp == ASN_OPAQUE_TAG1)) {

        /*
         * check if 64-but counter 
         */
        switch (*(bufp + 1)) {
        case ASN_OPAQUE_COUNTER64:
        case ASN_OPAQUE_U64:
        case ASN_OPAQUE_FLOAT:
        case ASN_OPAQUE_DOUBLE:
        case ASN_OPAQUE_I64:
            *type = *(bufp + 1);
            break;

        default:
            /*
             * just an Opaque 
             */
            *datalength = (int) asn_length;
            return bufp;
        }
        /*
         * value is encoded as special format 
         */
        bufp = asn_parse_length(bufp + 2, &asn_length);
        if (_asn_parse_length_check("parse opaque header", bufp, data,
                                    asn_length, *datalength))
            return NULL;
    }
#endif                          /* OPAQUE_SPECIAL_TYPES */

    *datalength = (int) asn_length;

    return bufp;
}

/*
 * same as asn_parse_header with test for expected type.
 */
u_char         *
asn_parse_sequence(u_char * data, size_t * datalength, u_char * type, u_char expected_type,     /* must be this type */
                   const char *estr)
{                               /* error message prefix */
    data = asn_parse_header(data, datalength, type);
    if (data && (*type != expected_type)) {
        char            ebuf[128];
        snprintf(ebuf, sizeof(ebuf),
                 "%s header type %02X: s/b %02X", estr,
                (u_char) * type, (u_char) expected_type);
        ebuf[ sizeof(ebuf)-1 ] = 0;
        ERROR_MSG(ebuf);
        return NULL;
    }
    return data;
}



/*
 * asn_build_header - builds an ASN header for an object with the ID and
 * length specified.
 *  On entry, datalength is input as the number of valid bytes following
 *   "data".  On exit, it is returned as the number of valid bytes
 *   in this object following the id and length.
 *
 *  This only works on data types < 30, i.e. no extension octets.
 *  The maximum length is 0xFFFF;
 *
 *  Returns a pointer to the first byte of the contents of this object.
 *  Returns NULL on any error.
 
 u_char * asn_build_header(
 u_char     *data         IN - pointer to start of object
 size_t     *datalength   IN/OUT - number of valid bytes left in buffer
 u_char      type         IN - asn type of object
 size_t      length       IN - length of object
 */
u_char         *
asn_build_header(u_char * data,
                 size_t * datalength, u_char type, size_t length)
{
    char            ebuf[128];

    if (*datalength < 1) {
        snprintf(ebuf, sizeof(ebuf),
                "bad header length < 1 :%d, %d", *datalength,
                length);
        ebuf[ sizeof(ebuf)-1 ] = 0;
        ERROR_MSG(ebuf);
        return NULL;
    }
    *data++ = type;
    (*datalength)--;
    return asn_build_length(data, datalength, length);
}

/*
 * asn_build_sequence - builds an ASN header for a sequence with the ID and
 * length specified.
 *  On entry, datalength is input as the number of valid bytes following
 *   "data".  On exit, it is returned as the number of valid bytes
 *   in this object following the id and length.
 *
 *  This only works on data types < 30, i.e. no extension octets.
 *  The maximum length is 0xFFFF;
 *
 *  Returns a pointer to the first byte of the contents of this object.
 *  Returns NULL on any error.
 
 u_char * asn_build_sequence(
 u_char     *data         IN - pointer to start of object
 int        *datalength   IN/OUT - number of valid bytes left in buffer
 u_char      type         IN - asn type of object
 int         length       IN - length of object
 */
u_char         *
asn_build_sequence(u_char * data,
                   size_t * datalength, u_char type, size_t length)
{
    static const char *errpre = "build seq";
    char            ebuf[128];

    if (*datalength < 4) {
        snprintf(ebuf, sizeof(ebuf),
                "%s: length %d < 4: PUNT", errpre,
                (int) *datalength);
        ebuf[ sizeof(ebuf)-1 ] = 0;
        ERROR_MSG(ebuf);
        return NULL;
    }
    *datalength -= 4;
    *data++ = type;
    *data++ = (u_char) (0x02 | ASN_LONG_LEN);
    *data++ = (u_char) ((length >> 8) & 0xFF);
    *data++ = (u_char) (length & 0xFF);
    return data;
}

/*