decode.c

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/*
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 *
 *   This library 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
 *   Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: 2b1da445986e08f1de2618b250c4f15aa3ba2cb4 $
 *
 * @file protocols/dhcpv4/decode.c
 * @brief Functions to decode DHCP options.
 *
 * @copyright 2008,2017 The FreeRADIUS server project
 * @copyright 2008 Alan DeKok (aland@deployingradius.com)
 * @copyright 2015,2017 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
#include <freeradius-devel/io/test_point.h>
#include <freeradius-devel/util/proto.h>
#include <freeradius-devel/util/struct.h>
#include <freeradius-devel/util/dns.h>
 
#include "dhcpv4.h"
#include "attrs.h"
 
static _Thread_local uint8_t    concat_buffer[1500]; /* ethernet max */
 
static ssize_t decode_option(TALLOC_CTX *ctx, fr_pair_list_t *out,
                              fr_dict_attr_t const *parent,
                              uint8_t const *data, size_t const data_len, void *decode_ctx);
 
static bool verify_tlvs(uint8_t const *data, size_t data_len)
{
        uint8_t const *p = data;
        uint8_t const *end = data + data_len;
 
        while (p < end) {
                if ((end - p) < 2) return false;
 
                if ((p + p[1]) > end) return false;
 
                p += 2 + p[1];
        }
 
        return true;
}
 
static ssize_t decode_tlv_trampoline(TALLOC_CTX *ctx, fr_pair_list_t *out,
                                     fr_dict_attr_t const *parent,
                                     uint8_t const *data, size_t const data_len, void *decode_ctx)
{
        return fr_pair_tlvs_from_network(ctx, out, parent, data, data_len, decode_ctx, decode_option, verify_tlvs, true);
}
 
static ssize_t decode_value(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t const *parent,
                            uint8_t const *data, size_t data_len, void *decode_ctx);
 
/** Handle arrays of DNS labels for fr_struct_from_network()
 *
 */
static ssize_t decode_value_trampoline(TALLOC_CTX *ctx, fr_pair_list_t *out,
                                       fr_dict_attr_t const *parent,
                                       uint8_t const *data, size_t const data_len, void *decode_ctx)
{
        FR_PROTO_TRACE("decode_value_trampoline of %s with %zu bytes", parent->name, data_len);
 
        /*
         *      @todo - we might need to limit this to only one DNS label.
         */
        if ((parent->type == FR_TYPE_STRING) && fr_dhcpv4_flag_dns_label(parent)) {
                return fr_pair_dns_labels_from_network(ctx, out, parent, data, data, data_len, NULL, false);
        }
 
        return decode_value(ctx, out, parent, data, data_len, decode_ctx);
}
 
/*
 *      Decode ONE value into a VP
 */
static ssize_t decode_value(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t const *da,
                            uint8_t const *data, size_t data_len, void *decode_ctx)
{
        ssize_t slen;
        fr_pair_t *vp;
        uint8_t const *p = data;
        uint8_t const *end = data + data_len;
        bool exact = !da->flags.array;
 
        FR_PROTO_TRACE("%s called to parse %zu bytes from %s", __FUNCTION__, data_len, da->name);
        FR_PROTO_HEX_DUMP(data, data_len, NULL);
 
        /*
         *      Structs create their own VP wrapper.
         */
        if (da->type == FR_TYPE_STRUCT) {
                slen = fr_struct_from_network(ctx, out, da, data, data_len,
                                              decode_ctx, decode_value_trampoline, decode_tlv_trampoline);
                if (slen < 0) return slen;
 
                if (!exact) return slen;
 
                return data_len;
        }
 
        /*
         *      These are always raw.
         */
        if (da->flags.is_unknown) {
                return fr_pair_raw_from_network(ctx, out, da, data, data_len);
        }
 
        vp = fr_pair_afrom_da(ctx, da);
        if (!vp) return PAIR_DECODE_OOM;
 
        /*
         *      string / octets / bool can be empty.  Other data types are
         *      raw if they're empty.
         */
        if (data_len == 0) {
                if (da->type == FR_TYPE_BOOL) {
                        vp->vp_bool = true;
                        goto finish;
                }
 
                if ((da->type == FR_TYPE_OCTETS) || (da->type == FR_TYPE_STRING)) {
                        goto finish;
                }
 
                talloc_free(vp);
                return fr_pair_raw_from_network(ctx, out, da, data, 0);
        }
 
        switch (vp->vp_type) {
        /*
         *      Doesn't include scope, whereas the generic format can
         */
        case FR_TYPE_IPV6_ADDR:
                if ((size_t) (end - p) < sizeof(vp->vp_ipv6addr)) goto raw;
 
                if (exact && ((size_t) (end - p) > sizeof(vp->vp_ipv6addr))) goto raw;
 
                memcpy(&vp->vp_ipv6addr, p, sizeof(vp->vp_ipv6addr));
                vp->vp_ip.af = AF_INET6;
                vp->vp_ip.scope_id = 0;
                vp->vp_ip.prefix = 128;
                vp->vp_tainted = true;
                p += sizeof(vp->vp_ipv6addr);
                break;
 
        case FR_TYPE_IPV6_PREFIX:
                if ((size_t) (end - (p + 1)) < sizeof(vp->vp_ipv6addr)) goto raw;
 
                if (exact && ((size_t) (end - p) > sizeof(vp->vp_ipv6addr))) goto raw;
 
                memcpy(&vp->vp_ipv6addr, p + 1, sizeof(vp->vp_ipv6addr));
                vp->vp_ip.af = AF_INET6;
                vp->vp_ip.scope_id = 0;
                vp->vp_ip.prefix = p[0];
                vp->vp_tainted = true;
                p += sizeof(vp->vp_ipv6addr) + 1;
                break;
 
        case FR_TYPE_STRUCTURAL:
                fr_strerror_printf("Cannot decode type '%s' as value", fr_type_to_str(vp->vp_type));
                talloc_free(vp);
                return 0;
 
        case FR_TYPE_IPV4_PREFIX:
                fr_value_box_init(&vp->data, FR_TYPE_IPV4_PREFIX, vp->da, true);
                vp->vp_ip.af = AF_INET;
 
                /*
                 *      4 octets of address
                 *      4 octets of mask
                 */
                if (fr_dhcpv4_flag_prefix_split(da)) {
                        uint32_t ipaddr, mask;
 
                        if (data_len < 8) goto raw;
 
                        ipaddr = fr_nbo_to_uint32(p);
                        mask = fr_nbo_to_uint32(p + 4);
                        p += 8;
 
                        /*
                         *      0/0 means a prefix of 0, too.
                         */
                        if (!mask) {
                                break;
                        }
 
                        /*
                         *      Try to figure out the prefix value from the mask.
                         */
                        while (mask) {
                                vp->vp_ip.prefix++;
                                mask <<= 1;
                        }
 
                        /*
                         *      Mash the IP based on the calculated mask.  We don't really care if the mask
                         *      has holes, or if the IP address overlaps with the mask.  We just fix it all up
                         *      so it's sane.
                         */
                        mask = ~(uint32_t) 0;
                        mask <<= (32 - vp->vp_ip.prefix);
 
                        vp->vp_ipv4addr = htonl(ipaddr & mask);
                        break;
                }
 
                if (fr_dhcpv4_flag_prefix_bits(vp->da)) {
                        size_t needs;
 
                        if ((data_len == 0) || (*p > 32)) goto raw;
 
                        needs = 1 + ((*p + 0x07) >> 3);
                        if (data_len < needs) goto raw;
 
                        /*
                         *      Don't do exact checks here, as the content is variable-sized.
                         */
 
                        vp->vp_ip.prefix = *p;
 
                        /*
                         *      If the IP address is longer than necessary, then only grab the pieces we need.
                         */
                        if (vp->vp_ip.prefix) {
                                uint32_t ipaddr, mask;
 
                                mask = ~(uint32_t) 0;
                                mask <<= (32 - vp->vp_ip.prefix);
 
                                if (*p > 24) {
                                        ipaddr = fr_nbo_to_uint32(p + 1);
 
                                } else if (*p > 16) {
                                        ipaddr = fr_nbo_to_uint24(p + 1);
                                        ipaddr <<= 8;
 
                                } else if (*p > 8) {
                                        ipaddr = fr_nbo_to_uint16(p + 1);
                                        ipaddr <<= 16;
 
                                } else { /* 1..8 */
                                        ipaddr = p[1];
                                        ipaddr <<= 24;
                                }
 
                                vp->vp_ipv4addr = htonl(ipaddr & mask);
                        } /* else *p==0, and we leave ipaddr set to zero */
 
                        p += needs;
                        break;
                }
 
                FALL_THROUGH;
 
        default:
                slen = fr_value_box_from_network(vp, &vp->data, vp->vp_type, da,
                                                 &FR_DBUFF_TMP(p, end - p), end - p, true);
                if (slen < 0) {
                raw:
                        FR_PROTO_TRACE("decoding as unknown type");
                        if (fr_pair_raw_afrom_pair(vp, p, (end - p)) < 0) {
                                return -1;
                        }
                        p = end;
                        break;
                }
 
                if (exact && (slen != (end - p))) {
                        goto raw;
                }
 
                p += (size_t) slen;
                break;
        }
 
finish:
        FR_PROTO_TRACE("decoding value complete, adding new pair and returning %zu byte(s)", (size_t) (p - data));
        fr_pair_append(out, vp);
 
        return p - data;
}
 
/** RFC 4243 Vendor Specific Suboptions
 *
 * Vendor specific suboptions are in the format.
 @verbatim
      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Enterprise Number 0                       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Len 0      |                                               /
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     /                      Suboption Data 0                         /
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Enterprise Number n                       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Len n      |                                               /
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     /                      Suboption Data n                         /
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 @endverbatim
 *
 * So although the vendor is identified, the format of the data isn't
 * specified so we can't actually resolve the suboption to an
 * attribute.  For now, we just convert it to an attribute of
 * Vendor-Specific-Information with raw octets contents.
 */
 
 
/*
 *  One VSA option may contain multiple vendors, each vendor
 *  may contain one or more sub-options.
 *
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |  option-code  |  option-len   |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |      enterprise-number1       |
 *  |                               |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |   data-len1   |               |
 *  +-+-+-+-+-+-+-+-+ option-data1  |
 *  /                               /
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ----
 *  |      enterprise-number2       |   ^
 *  |                               |   |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |
 *  |   data-len2   |               | optional
 *  +-+-+-+-+-+-+-+-+ option-data2  |   |
 *  /                               /   |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |
 *  ~            ...                ~   V
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ----
 */
static ssize_t decode_vsa(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t const *parent,
                          uint8_t const *data, size_t const data_len, void *decode_ctx)
{
        ssize_t                 len;
        uint8_t                 option_len;
        uint32_t                pen;
        fr_pair_t               *vp;
        fr_dict_attr_t const    *vendor;
        uint8_t const           *end = data + data_len;
        uint8_t const           *p = data;
 
        FR_PROTO_HEX_DUMP(data, data_len, "decode_vsa");
 
        if (!fr_cond_assert_msg(parent->type == FR_TYPE_VSA,
                                "%s: Internal sanity check failed, attribute \"%s\" is not of type 'vsa'",
                                __FUNCTION__, parent->name)) return PAIR_DECODE_FATAL_ERROR;
 
next:
        /*
         *      We need at least 4 (PEN) + 1 (data-len) + 1 (vendor option num) to be able to decode vendor
         *      specific attributes.  If we don't have that, then we return an error.  The caller will free
         *      the VSA, and create a "raw.VSA" attribute.
         */
        if ((size_t)(end - p) < (sizeof(uint32_t) + 1 + 1)) {
                return -1;
        }
 
        pen = fr_nbo_to_uint32(p);
 
        /*
         *      Verify that the parent (which should be a VSA)
         *      contains a fake attribute representing the vendor.
         *
         *      If it doesn't then this vendor is unknown, but we know
         *      vendor attributes have a standard format, so we can
         *      decode the data anyway.
         */
        vendor = fr_dict_attr_child_by_num(parent, pen);
        if (!vendor) {
                fr_dict_attr_t *n;
 
                n = fr_dict_attr_unknown_vendor_afrom_num(ctx, parent, pen);
                if (!n) return PAIR_DECODE_OOM;
                vendor = n;
        }
        p += sizeof(uint32_t);
 
        FR_PROTO_TRACE("decode context %s -> %s", parent->name, vendor->name);
 
        option_len = p[0];
        if ((p + 1 + option_len) > end) {
                len = fr_pair_raw_from_network(ctx, out, vendor, p, end - p);
                if (len < 0) return len;
 
                return data_len + 2; /* decoded the whole thing */
        }
        p++;
 
        /*
         *      Pathological case of no data.
         */
        if (option_len == 0) goto next;
 
        vp = fr_pair_find_by_da(out, NULL, vendor);
        if (!vp) {
                vp = fr_pair_afrom_da(ctx, vendor);
                if (!vp) return PAIR_DECODE_FATAL_ERROR;
 
                fr_pair_append(out, vp);
        }
 
        len = fr_pair_tlvs_from_network(vp, &vp->vp_group, vendor, p, option_len, decode_ctx, decode_option, verify_tlvs, false);
        if (len < 0) return len;
 
        p += option_len;
        if (p < end) goto next;
 
        /*
         *      Tell the caller we read all of it, even if we didn't.
         */
        return data_len + 2;
}
 
 
static ssize_t decode_option(TALLOC_CTX *ctx, fr_pair_list_t *out,
                              fr_dict_attr_t const *parent,
                              uint8_t const *data, size_t const data_len, void *decode_ctx)
{
        unsigned int            option;
        size_t                  len;
        ssize_t                 slen;
        fr_dict_attr_t const    *da;
        fr_dhcpv4_ctx_t         *packet_ctx = decode_ctx;
 
#ifdef STATIC_ANALYZER
        if (!packet_ctx || !packet_ctx->tmp_ctx) return PAIR_DECODE_FATAL_ERROR;
#endif
 
        fr_assert(parent != NULL);
 
        /*
         *      RFC 3046 is very specific about not allowing termination
         *      with a 255 sub-option. But it's required for decoding
         *      option 43, and vendors will probably screw it up
         *      anyway.
         *
         *      Similarly, option 0 is sometimes treated as
         *      "end of options".
         *
         *      @todo - this check is likely correct only when at the
         *      dhcpv4 root, OR inside of option 43.  It could be
         *      argued that it's wrong for all other TLVs.
         */
        if ((data_len == 1) && ((data[0] == 0) || (data[1] == 255))) return data_len;
 
        /*
         *      Must have at least an option header.
         */
        if (data_len < 2) {
                fr_strerror_printf("%s: Insufficient data", __FUNCTION__);
                return -(data_len);
        }
 
        option = data[0];
        len = data[1];
        if (len > (data_len - 2)) {
                fr_strerror_printf("%s: Option overflows input.  "
                                   "Optional length must be less than %zu bytes, got %zu bytes",
                                   __FUNCTION__, data_len - 2, len);
                return PAIR_DECODE_FATAL_ERROR;
        }
 
        da = fr_dict_attr_child_by_num(parent, option);
        if (!da) {
                da = fr_dict_attr_unknown_raw_afrom_num(packet_ctx->tmp_ctx, parent, option);
                if (!da) return PAIR_DECODE_OOM;
 
                slen = fr_pair_raw_from_network(ctx, out, da, data + 2, len);
 
        } else if ((da->type == FR_TYPE_STRING) && fr_dhcpv4_flag_dns_label(da)) {
                slen = fr_pair_dns_labels_from_network(ctx, out, da, data + 2, data + 2, len, NULL, true);
 
        } else if (da->flags.array) {
                slen = fr_pair_array_from_network(ctx, out, da, data + 2, len, decode_ctx, decode_value);
 
        } else if (da->type == FR_TYPE_VSA) {
                bool append = false;
                fr_pair_t *vp;
 
                vp = fr_pair_find_by_da(out, NULL, da);
                if (!vp) {
                        vp = fr_pair_afrom_da(ctx, da);
                        if (!vp) return PAIR_DECODE_FATAL_ERROR;
 
                        append = true;
                }
 
                slen = decode_vsa(vp, &vp->vp_group, da, data + 2, len, decode_ctx);
                if (append) {
                        if (slen < 0) {
                                TALLOC_FREE(vp);
                        } else {
                                fr_pair_append(out, vp);
                        }
                }
 
        } else if (da->type == FR_TYPE_TLV) {
                slen = fr_pair_tlvs_from_network(ctx, out, da, data + 2, len, decode_ctx, decode_option, verify_tlvs, true);
 
        } else {
                slen = decode_value(ctx, out, da, data + 2, len, decode_ctx);
        }
 
        if (slen < 0) {
                slen = fr_pair_raw_from_network(ctx, out, da, data + 2, len);
                if (slen < 0) return slen;
        }
 
        return len + 2;
}
 
/** Decode DHCP option
 *
 * @param[in] ctx context       to alloc new attributes in.
 * @param[out] out              Where to write the decoded options.
 * @param[in] data              to parse.
 * @param[in] data_len          of data to parse.
 * @param[in] decode_ctx        Unused.
 */
ssize_t fr_dhcpv4_decode_option(TALLOC_CTX *ctx, fr_pair_list_t *out,
                                uint8_t const *data, size_t data_len, void *decode_ctx)
{
        ssize_t                 slen;
        uint8_t const           *p = data, *end = data + data_len;
        uint8_t const           *next;
        fr_dhcpv4_ctx_t         *packet_ctx = decode_ctx;
 
        FR_PROTO_TRACE("%s called to parse %zu byte(s)", __FUNCTION__, data_len);
 
        if (data_len == 0) return 0;
 
        FR_PROTO_HEX_DUMP(data, data_len, NULL);
 
        /*
         *      Padding / End of options
         */
        if (p[0] == 0) {                        /* 0x00 - Padding option          */
                data_len = 1;                   /* Walk over any consecutive 0x00 */
                p++;                            /* for efficiency                 */
                while ((p < end) && (p[0] == 0)) {
                        p++;
                        data_len ++;
                }
                return data_len;
        }
        if (p[0] == 255) return data_len;       /* 0xff - End of options signifier */
 
        /*
         *      Everything else should be real options
         */
        if ((data_len < 2) || ((size_t) (data[1] + 2) > data_len)) {
                fr_strerror_printf("%s: Insufficient data", __FUNCTION__);
                return -1;
        }
 
        /*
         *      Check for multiple options of the same type, and concatenate their values together.
         *
         *      RFC 2131 Section 4.1 says:
         *
         *        The client concatenates the values of multiple
         *        instances of the same option into a single parameter
         *        list for configuration.
         *
         *      which presumably also means the same for the server on reception.
         *
         *      We therefore peek ahead, and concatenate the values into a temporary buffer.  The buffer is
         *      allocated only if necessary, and is re-used for the entire packet.
         *
         *      If the options are *not* consecutive, then we don't concatenate them.  Too bad for you!
         *
         *      Note that we don't (yet) do this for TLVs.
         */
        next = data + 2 + data[1];
        if ((data[1] > 0) && (next < end) && (next[0] == data[0])) {
                uint8_t *q;
                fr_dict_attr_t const *da;
 
                q = concat_buffer;
 
                for (next = data; next < end; next += 2 + next[1]) {
                        if ((end - next) < 2) return -1;
                        if (next[0] != data[0]) break;
                        if ((next + 2 + next[1]) > end) return -1;
 
                        if ((size_t) (q + next[1] - concat_buffer) > sizeof(concat_buffer)) return -1;
 
                        memcpy(q, next + 2, next[1]);
                        q += next[1];
                }
 
                if (q == concat_buffer) return 0;
 
                da = fr_dict_attr_child_by_num(fr_dict_root(dict_dhcpv4), p[0]);
                if (!da) {
                        da = fr_dict_attr_unknown_raw_afrom_num(packet_ctx->tmp_ctx, fr_dict_root(dict_dhcpv4), p[0]);
                        if (!da) return -1;
 
                        slen = fr_pair_raw_from_network(ctx, out, da, concat_buffer, q - concat_buffer);
 
                } else if (da->type == FR_TYPE_VSA) {
                        slen = decode_vsa(ctx, out, da, concat_buffer, q - concat_buffer, packet_ctx);
 
                } else if (da->type == FR_TYPE_TLV) {
                        slen = fr_pair_tlvs_from_network(ctx, out, da, concat_buffer, q - concat_buffer,
                                                         packet_ctx, decode_option, verify_tlvs, true);
 
                } else if (da->flags.array) {
                        slen = fr_pair_array_from_network(ctx, out, da, concat_buffer, q - concat_buffer, packet_ctx, decode_value);
 
                } else {
                        slen = decode_value(ctx, out, da, concat_buffer, q - concat_buffer, packet_ctx);
                }
                if (slen < 0) return slen;
 
                /*
                 *      The actual amount of data we decoded, including the various headers.
                 */
                FR_PROTO_TRACE("decoding option complete, %zd decoded, returning %zu byte(s)", slen, (size_t) (next - data));
                return next - data;
        }
 
        slen = decode_option(ctx, out, fr_dict_root(dict_dhcpv4), data, data[1] + 2, decode_ctx);
        if (slen < 0) return slen;
 
        FR_PROTO_TRACE("decoding option complete, %zd decoded, returning %u byte(s)", slen, (unsigned int) data[1] + 2);
        return data[1] + 2;
}
 
ssize_t fr_dhcpv4_decode_foreign(TALLOC_CTX *ctx, fr_pair_list_t *out,
                                 uint8_t const *data, size_t data_len)
{
        ssize_t slen;
        uint8_t const *attr, *end;
 
        fr_dhcpv4_ctx_t decode_ctx = {};
 
        fr_assert(dict_dhcpv4 != NULL);
 
        decode_ctx.tmp_ctx = talloc(ctx, uint8_t);
 
        attr = data;
        end = data + data_len;
 
        while (attr < end) {
                slen = fr_dhcpv4_decode_option(ctx, out, attr, (end - attr), &decode_ctx);
                if (slen < 0) {
                        talloc_free(decode_ctx.tmp_ctx);
                        return slen;
                }
 
                /*
                 *      If slen is larger than the room in the packet,
                 *      all kinds of bad things happen.
                 */
                 if (!fr_cond_assert(slen <= (end - attr))) {
                        talloc_free(decode_ctx.tmp_ctx);
                         return -slen - (attr - data);
                 }
 
                attr += slen;
                talloc_free_children(decode_ctx.tmp_ctx);
        }
 
        talloc_free(decode_ctx.tmp_ctx);
        return data_len;
}
 
 
static int decode_test_ctx(void **out, TALLOC_CTX *ctx, UNUSED fr_dict_t const *dict)
{
        fr_dhcpv4_ctx_t *test_ctx;
 
        test_ctx = talloc_zero(ctx, fr_dhcpv4_ctx_t);
        test_ctx->tmp_ctx = talloc(test_ctx, uint8_t);
 
        *out = test_ctx;
 
        return 0;
}
 
 
static ssize_t fr_dhcpv4_decode_proto(TALLOC_CTX *ctx, fr_pair_list_t *out,
                                      uint8_t const *data, size_t data_len, UNUSED void *proto_ctx)
{
        unsigned int    code;
 
        if (!fr_dhcpv4_ok(data, data_len, NULL, NULL)) return -1;
 
        if (fr_dhcpv4_decode(ctx, out, data, data_len, &code) < 0) return -1;
 
        return data_len;
}
 
static ssize_t decode_option_wrapper(TALLOC_CTX *ctx, fr_pair_list_t *out, NDEBUG_UNUSED fr_dict_attr_t const *parent,
                                uint8_t const *data, size_t data_len, void *decode_ctx)
{
        fr_assert(parent == fr_dict_root(dict_dhcpv4));
 
        return fr_dhcpv4_decode_option(ctx, out, data, data_len, decode_ctx);
}
 
/*
 *      Test points
 */
extern fr_test_point_pair_decode_t dhcpv4_tp_decode_pair;
fr_test_point_pair_decode_t dhcpv4_tp_decode_pair = {
        .test_ctx       = decode_test_ctx,
        .func           = decode_option_wrapper
};
 
extern fr_test_point_proto_decode_t dhcpv4_tp_decode_proto;
fr_test_point_proto_decode_t dhcpv4_tp_decode_proto = {
        .test_ctx       = decode_test_ctx,
        .func           = fr_dhcpv4_decode_proto
};