vmps.c

Go to the documentation of this file.

/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: cadd09910a18e6a496a7e905c91acd7a2668af9d $
 *
 * @file src/protocols/vmps/vmps.c
 * @brief Functions to send/receive VQP packets.
 *
 * @copyright 2007 Alan DeKok (aland@deployingradius.com)
 */
 
RCSID("$Id: cadd09910a18e6a496a7e905c91acd7a2668af9d $")
 
#include <freeradius-devel/io/test_point.h>
#include <freeradius-devel/protocol/vmps/vmps.h>
#include <freeradius-devel/util/dbuff.h>
#include <freeradius-devel/util/proto.h>
#include <freeradius-devel/util/udp.h>
 
#include "vmps.h"
#include "attrs.h"
 
/** Used as the decoder ctx
 *
 */
typedef struct {
        int             nothing;
} fr_vmps_ctx_t;
 
/*
 *  http://www.openbsd.org/cgi-bin/cvsweb/src/usr.sbin/tcpdump/print-vqp.c
 *
 *  Chapter 12 of Hacking Cisco Networks Exposed (Vladimirov, Gavrilenko,
 *  and Mikhailovsky, McGraw-Hill 2005)  describes some of how it works.
 *
 * VLAN Query Protocol (VQP)
 *
 *   0                   1                   2                   3
 *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |    Version    |    Opcode     | Response Code |  Data Count   |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |                         Transaction ID                        |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |                            Type (1)                           |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |             Length            |            Data               /
 *  /                                                               /
 *  /                                                               /
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |                            Type (n)                           |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |             Length            |            Data               /
 *  /                                                               /
 *  /                                                               /
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * VQP is layered over UDP.  The default destination port is 1589.
 *
 */
char const *fr_vmps_packet_names[FR_VMPS_CODE_MAX] = {
        [FR_PACKET_TYPE_VALUE_JOIN_REQUEST] = "Join-Request",
        [FR_PACKET_TYPE_VALUE_JOIN_RESPONSE] = "Join-Response",
        [FR_PACKET_TYPE_VALUE_RECONFIRM_REQUEST] = "Reconfirm-Request",
        [FR_PACKET_TYPE_VALUE_RECONFIRM_RESPONSE] = "Reconfirm-Response",
};
 
 
bool fr_vmps_ok(uint8_t const *packet, size_t *packet_len)
{
        uint8_t const   *ptr;
        ssize_t         data_len;
        int             attrlen;
 
        if (*packet_len == FR_VQP_HDR_LEN) return true;
 
        /*
         *      Skip the header.
         */
        ptr = packet + FR_VQP_HDR_LEN;
        data_len = *packet_len - FR_VQP_HDR_LEN;
 
        while (data_len > 0) {
                if (data_len < 7) {
                        fr_strerror_const("Packet contains malformed attribute");
                        return false;
                }
 
                /*
                 *      Attributes are 4 bytes
                 *      0x00000c01 ... 0x00000c08
                 */
                if ((ptr[0] != 0) || (ptr[1] != 0) ||
                    (ptr[2] != 0x0c) || (ptr[3] < 1) || (ptr[3] > 8)) {
                        fr_strerror_const("Packet contains invalid attribute");
                        return false;
                }
 
                /*
                 *      Length is 2 bytes
                 */
                attrlen = fr_nbo_to_uint16(ptr + 4);
 
                /*
                 *      Total of attribute lengths shouldn't exceed *packet_len - header length,
                 *      which happens iff at some point, attrlen exceeds data_lan.
                 */
                if (attrlen > data_len) {
                        fr_strerror_printf("Packet attributes cause total length "
                                           "plus header length to exceed packet length %lx",
                                           *packet_len);
                        return false;
                }
 
                /*
                 *      We support short lengths, as there's no reason
                 *      for bigger lengths to exist... admins won't be
                 *      typing in a 32K vlan name.
                 *
                 *      It's OK for ethernet frames to be longer.
                 */
                if ((ptr[3] != 5) && (attrlen > 250)) {
                        fr_strerror_printf("Packet contains attribute with invalid length %02x %02x", ptr[4], ptr[5]);
                        return false;
                }
 
                ptr += 6 + attrlen;
                data_len -= (6 + attrlen);
        }
 
        /*
         *      UDP reads may return too much data, so we truncate it.
         */
        *packet_len = ptr - packet;
 
        return true;
}
 
 
int fr_vmps_decode(TALLOC_CTX *ctx, fr_pair_list_t *out, uint8_t const *data, size_t data_len, unsigned int *code)
{
        uint8_t const   *ptr, *end;
        int             attr;
        size_t          attr_len;
        fr_pair_t       *vp;
 
        if (data_len < FR_VQP_HDR_LEN) return -1;
 
        vp = fr_pair_afrom_da(ctx, attr_packet_type);
        if (!vp) {
        oom:
                fr_strerror_const("Out of Memory");
                return -1;
        }
        vp->vp_uint32 = data[1];
        if (code) *code = data[1];
        vp->vp_tainted = true;
        DEBUG2("&%pP", vp);
        fr_pair_append(out, vp);
 
        vp = fr_pair_afrom_da(ctx, attr_error_code);
        if (!vp) goto oom;
        vp->vp_uint32 = data[2];
        vp->vp_tainted = true;
        DEBUG2("&%pP", vp);
        fr_pair_append(out, vp);
 
        vp = fr_pair_afrom_da(ctx, attr_sequence_number);
        if (!vp) goto oom;
 
        vp->vp_uint32 = fr_nbo_to_uint32(data + 4);
        vp->vp_tainted = true;
        DEBUG2("&%pP", vp);
        fr_pair_append(out, vp);
 
        ptr = data + FR_VQP_HDR_LEN;
        end = data + data_len;
 
        /*
         *      Note that vmps_recv() MUST ensure that the packet is
         *      formatted in a way we expect, and that vmps_recv() MUST
         *      be called before vmps_decode().
         */
        while (ptr < end) {
                if ((end - ptr) < 6) {
                        fr_strerror_printf("Packet is too small. (%ld < 6)", (end - ptr));
                        return -1;
                }
 
                attr = fr_nbo_to_uint16(ptr + 2);
                attr_len = fr_nbo_to_uint16(ptr + 4);
                ptr += 6;
 
                /*
                 *      fr_vmps_ok() should have checked this already,
                 *      but it doesn't hurt to do it again.
                 */
                if (attr_len > (size_t) (end - ptr)) {
                        fr_strerror_const("Attribute length exceeds received data");
                        return -1;
                }
 
                /*
                 *      Create the VP.
                 */
                vp = fr_pair_afrom_child_num(ctx, fr_dict_root(dict_vmps), attr);
                if (!vp) {
                        fr_strerror_const("No memory");
                        return -1;
                }
 
                /*
                 *      Rely on value_box to do the work.
                 *
                 *      @todo - if the attribute is malformed, create a "raw" one.
                 */
                if (fr_value_box_from_network(vp, &vp->data, vp->vp_type, vp->da,
                                              &FR_DBUFF_TMP(ptr, attr_len), attr_len, true) < 0) {
                        talloc_free(vp);
                        return -1;
                }
 
                ptr += attr_len;
                vp->vp_tainted = true;
                DEBUG2("&%pP", vp);
                fr_pair_append(out, vp);
        }
 
        /*
         *      FIXME: Map attributes to Calling-Station-Id, etc...
         */
 
        return data_len;
}
 
#if 0
/*
 *      These are the MUST HAVE contents for a VQP packet.
 *
 *      We don't allow the caller to give less than these, because
 *      it won't work.  We don't encode more than these, because the
 *      clients will ignore it.
 *
 *      FIXME: Be more generous?  Look for CISCO + VQP attributes?
 *
 *      @todo - actually use these again...
 */
static int contents[5][VQP_MAX_ATTRIBUTES] = {
        { 0,      0,      0,      0,      0,      0 },
        { 0x0c01, 0x0c02, 0x0c03, 0x0c04, 0x0c07, 0x0c05 }, /* Join request */
        { 0x0c03, 0x0c08, 0,      0,      0,      0 },  /* Join Response */
        { 0x0c01, 0x0c02, 0x0c03, 0x0c04, 0x0c07, 0x0c08 }, /* Reconfirm */
        { 0x0c03, 0x0c08, 0,      0,      0,      0 }
};
#endif
 
ssize_t fr_vmps_encode(fr_dbuff_t *dbuff, uint8_t const *original,
                       int code, uint32_t seq_no, fr_dcursor_t *cursor)
{
        fr_dbuff_t              work_dbuff = FR_DBUFF(dbuff);
        fr_pair_t               *vp;
        fr_dbuff_marker_t       hdr, m;
        uint8_t                 data_count = 0;
 
        /*
         *      Let's keep a reference for packet header, and another
         *      to let us write to to the encoding as needed.
         */
        fr_dbuff_marker(&hdr, &work_dbuff);
        fr_dbuff_marker(&m, &work_dbuff);
 
        /*
         *      Create the header
         */
        FR_DBUFF_IN_BYTES_RETURN(&work_dbuff, FR_VQP_VERSION,                   /* Version */
                                              code,                             /* Opcode */
                                              FR_ERROR_CODE_VALUE_NO_ERROR,     /* Response Code */
                                              data_count);                      /* Data Count */
 
        if (original) {
                FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, original + 4, 4);
        } else {
                FR_DBUFF_IN_RETURN(&work_dbuff, seq_no);
        }
 
        /*
         *      Encode the VP's.
         */
        while ((vp = fr_dcursor_current(cursor))) {
                ssize_t slen;
 
                if (vp->da == attr_packet_type) {
                        fr_dbuff_set(&m, fr_dbuff_current(&hdr) + 1);
                        FR_DBUFF_IN_RETURN(&m, (uint8_t)vp->vp_uint32);
                        fr_dcursor_next(cursor);
                        continue;
                }
 
                if (vp->da == attr_error_code) {
                        fr_dbuff_set(&m, fr_dbuff_current(&hdr) + 2);
                        FR_DBUFF_IN_RETURN(&m, vp->vp_uint8);
                        fr_dcursor_next(cursor);
                        continue;
                }
 
                if (!original && (vp->da == attr_sequence_number)) {
                        fr_dbuff_set(&m, fr_dbuff_current(&hdr) + 4);
                        FR_DBUFF_IN_RETURN(&m, vp->vp_uint32);
                        fr_dcursor_next(cursor);
                        continue;
                }
 
                if (!fr_type_is_leaf(vp->vp_type)) continue;
 
                DEBUG2("&%pP", vp);
 
                /*
                 *      Type.  Note that we look at only the lower 8
                 *      bits, as the upper 8 bits have been hacked.
                 *      See also dictionary.vmps
                 */
 
                /* Type */
                FR_DBUFF_IN_BYTES_RETURN(&work_dbuff, 0x00, 0x00, 0x0c, (vp->da->attr & 0xff));
 
                /* Length */
                fr_dbuff_set(&m, fr_dbuff_current(&work_dbuff));
                FR_DBUFF_IN_RETURN(&work_dbuff, (uint16_t) 0);
 
                /* Data */
                slen = fr_value_box_to_network(&work_dbuff, &vp->data);
                if (slen < 0) return slen;
 
                FR_DBUFF_IN_RETURN(&m, (uint16_t) slen);
 
                data_count++;
 
                fr_dcursor_next(cursor);
        }
 
        /*
         *      Update the Data Count
         */
        fr_dbuff_set(&m, fr_dbuff_current(&hdr) + 3);
        FR_DBUFF_IN_RETURN(&m, data_count);
 
        return fr_dbuff_set(dbuff, &work_dbuff);
}
 
 
/** See how big of a packet is in the buffer.
 *
 * Packet is not 'const * const' because we may update data_len, if there's more data
 * in the UDP packet than in the VMPS packet.
 *
 * @param data pointer to the packet buffer
 * @param data_len length of the packet buffer
 * @return
 *      <= 0 packet is bad.
 *      >0 how much of the data is a packet (can be larger than data_len)
 */
ssize_t fr_vmps_packet_size(uint8_t const *data, size_t data_len)
{
        int attributes;
        uint8_t const *ptr, *end;
 
        if (data_len < FR_VQP_HDR_LEN) return FR_VQP_HDR_LEN;
 
        /*
         *      No attributes.
         */
        if (data[3] == 0) return FR_VQP_HDR_LEN;
 
        /*
         *      Too many attributes.  Return an error indicating that
         *      there's a problem with octet 3.
         */
        if (data[3] > 30) return -3;
 
        /*
         *      Look for attributes.
         */
        ptr = data + FR_VQP_HDR_LEN;
        attributes = data[3];
 
        end = data + data_len;
 
        while (attributes > 0) {
                size_t attr_len;
 
                /*
                 *      Not enough room for the attribute headers, we
                 *      want at least those.
                 */
                if ((end - ptr) < 6) {
                        return 6 * attributes;
                }
 
                /*
                 *      Length of the data NOT including the header.
                 */
                attr_len = fr_nbo_to_uint16(ptr + 4);
 
                ptr += 6 + attr_len;
 
                /*
                 *      We don't want to read infinite amounts of data.
                 *
                 *      Return an error indicating that there's a
                 *      problem with the final octet
                 */
                if ((ptr - data) > 4096) {
                        return -(ptr - data);
                }
 
                /*
                 *      This attribute has been checked.
                 */
                attributes--;
 
                /*
                 *      The packet we want is larger than the input
                 *      buffer, so we return the length of the current
                 *      attribute, plus the length of the remaining
                 *      headers.
                 */
                if (ptr > end) return (6 * attributes) + ptr - data;
        }
 
        /*
         *      We've reached the end of the packet.
         */
        return ptr - data;
}
 
static void print_hex_data(uint8_t const *ptr, int attrlen, int depth)
{
        int i;
        static char const tabs[] = "\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t";
 
        for (i = 0; i < attrlen; i++) {
                if ((i > 0) && ((i & 0x0f) == 0x00))
                        fprintf(fr_log_fp, "%.*s", depth, tabs);
                fprintf(fr_log_fp, "%02x ", ptr[i]);
                if ((i & 0x0f) == 0x0f) fprintf(fr_log_fp, "\n");
        }
        if ((i & 0x0f) != 0) fprintf(fr_log_fp, "\n");
}
 
 
/** Print a raw VMPS packet as hex.
 *
 */
void fr_vmps_print_hex(FILE *fp, uint8_t const *packet, size_t packet_len)
{
        int length;
        uint8_t const *attr, *end;
        uint32_t id;
 
        if (packet_len < 8) return;
 
        fprintf(fp, "  Version:\t\t%u\n", packet[0]);
 
        if ((packet[1] > 0) && (packet[1] < FR_VMPS_CODE_MAX) && fr_vmps_packet_names[packet[1]]) {
                fprintf(fp, "  OpCode:\t\t%s\n", fr_vmps_packet_names[packet[1]]);
        } else {
                fprintf(fp, "  OpCode:\t\t%u\n", packet[1]);
        }
 
        if ((packet[2] > 0) && (packet[2] < FR_VMPS_CODE_MAX) && fr_vmps_packet_names[packet[2]]) {
                fprintf(fp, "  OpCode:\t\t%s\n", fr_vmps_packet_names[packet[2]]);
        } else {
                fprintf(fp, "  OpCode:\t\t%u\n", packet[2]);
        }
 
        fprintf(fp, "  Data Count:\t\t%u\n", packet[3]);
 
        memcpy(&id, packet + 4, 4);
        id = ntohl(id);
 
        fprintf(fp, "  ID:\t%08x\n", id);
 
        if (packet_len == 8) return;
 
        for (attr = packet + 8, end = packet + packet_len;
             attr < end;
             attr += length) {
                memcpy(&id, attr, 4);
                id = ntohl(id);
 
                length = fr_nbo_to_uint16(attr + 4);
                if (length > (end - attr)) break;
 
                fprintf(fp, "\t\t%08x  %04x  ", id, length);
 
                print_hex_data(attr + 6, length - 6, 3);
        }
}
 
/*
 *      Test points for protocol decode
 */
static ssize_t fr_vmps_decode_proto(TALLOC_CTX *ctx, fr_pair_list_t *out,
                                    uint8_t const *data, size_t data_len, void *proto_ctx)
{
        return fr_vmps_decode(ctx, out, data, data_len, proto_ctx);
}
 
static int _decode_test_ctx(UNUSED fr_vmps_ctx_t *proto_ctx)
{
        fr_vmps_global_free();
 
        return 0;
}
 
static int decode_test_ctx(void **out, TALLOC_CTX *ctx)
{
        fr_vmps_ctx_t *test_ctx;
 
        if (fr_vmps_global_init() < 0) return -1;
 
        test_ctx = talloc_zero(ctx, fr_vmps_ctx_t);
        if (!test_ctx) return -1;
 
        talloc_set_destructor(test_ctx, _decode_test_ctx);
 
        *out = test_ctx;
 
        return 0;
}
 
extern fr_test_point_proto_decode_t vmps_tp_decode_proto;
fr_test_point_proto_decode_t vmps_tp_decode_proto = {
        .test_ctx       = decode_test_ctx,
        .func           = fr_vmps_decode_proto
};
 
/*
 *      Test points for protocol encode
 */
static ssize_t fr_vmps_encode_proto(UNUSED TALLOC_CTX *ctx, fr_pair_list_t *vps, uint8_t *data, size_t data_len, UNUSED void *proto_ctx)
{
        fr_dcursor_t cursor;
 
        fr_pair_dcursor_iter_init(&cursor, vps, fr_proto_next_encodable, dict_vmps);
 
        return fr_vmps_encode(&FR_DBUFF_TMP(data, data_len), NULL, -1, -1, &cursor);
}
 
static int _encode_test_ctx(UNUSED fr_vmps_ctx_t *proto_ctx)
{
        fr_vmps_global_free();
 
        return 0;
}
 
static int encode_test_ctx(void **out, TALLOC_CTX *ctx)
{
        fr_vmps_ctx_t *test_ctx;
 
        if (fr_vmps_global_init() < 0) return -1;
 
        test_ctx = talloc_zero(ctx, fr_vmps_ctx_t);
        if (!test_ctx) return -1;
 
        talloc_set_destructor(test_ctx, _encode_test_ctx);
 
        *out = test_ctx;
 
        return 0;
}
 
extern fr_test_point_proto_encode_t vmps_tp_encode_proto;
fr_test_point_proto_encode_t vmps_tp_encode_proto = {
        .test_ctx       = encode_test_ctx,
        .func           = fr_vmps_encode_proto
};