base.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: 76c832f04ee6fffbc085bbf3850ea4adb4aafb11 $
 *
 * @file protocols/dhcpv4/base.c
 * @brief Functions to send/receive dhcp packets.
 *
 * @copyright 2008 The FreeRADIUS server project
 * @copyright 2008 Alan DeKok (aland@deployingradius.com)
 */
RCSID("$Id: 76c832f04ee6fffbc085bbf3850ea4adb4aafb11 $")
 
#include <freeradius-devel/dhcpv4/dhcpv4.h>
#include <freeradius-devel/util/net.h>
#include <freeradius-devel/util/proto.h>
#include "attrs.h"
 
static uint32_t instance_count = 0;
 
typedef struct {
        uint8_t         code;
        uint8_t         length;
} dhcp_option_t;
 
fr_dict_t const *dict_dhcpv4;
 
extern fr_dict_autoload_t dhcpv4_dict[];
fr_dict_autoload_t dhcpv4_dict[] = {
        { .out = &dict_dhcpv4, .proto = "dhcpv4" },
        { NULL }
};
 
fr_dict_attr_t const *attr_dhcp_boot_filename;
fr_dict_attr_t const *attr_dhcp_client_hardware_address;
fr_dict_attr_t const *attr_dhcp_client_ip_address;
fr_dict_attr_t const *attr_dhcp_flags;
fr_dict_attr_t const *attr_dhcp_gateway_ip_address;
fr_dict_attr_t const *attr_dhcp_hardware_address_length;
fr_dict_attr_t const *attr_dhcp_hardware_type;
fr_dict_attr_t const *attr_dhcp_hop_count;
fr_dict_attr_t const *attr_dhcp_number_of_seconds;
fr_dict_attr_t const *attr_dhcp_opcode;
fr_dict_attr_t const *attr_dhcp_server_host_name;
fr_dict_attr_t const *attr_dhcp_server_ip_address;
fr_dict_attr_t const *attr_dhcp_transaction_id;
fr_dict_attr_t const *attr_dhcp_your_ip_address;
fr_dict_attr_t const *attr_dhcp_dhcp_maximum_msg_size;
fr_dict_attr_t const *attr_dhcp_interface_mtu_size;
fr_dict_attr_t const *attr_dhcp_message_type;
fr_dict_attr_t const *attr_dhcp_parameter_request_list;
fr_dict_attr_t const *attr_dhcp_overload;
fr_dict_attr_t const *attr_dhcp_vendor_class_identifier;
fr_dict_attr_t const *attr_dhcp_relay_link_selection;
fr_dict_attr_t const *attr_dhcp_subnet_selection_option;
fr_dict_attr_t const *attr_dhcp_network_subnet;
 
extern fr_dict_attr_autoload_t dhcpv4_dict_attr[];
fr_dict_attr_autoload_t dhcpv4_dict_attr[] = {
        { .out = &attr_dhcp_boot_filename, .name = "Boot-Filename", .type = FR_TYPE_STRING, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_client_hardware_address, .name = "Client-Hardware-Address", .type = FR_TYPE_ETHERNET, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_client_ip_address, .name = "Client-IP-Address", .type = FR_TYPE_IPV4_ADDR, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_flags, .name = "Flags", .type = FR_TYPE_UINT16, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_gateway_ip_address, .name = "Gateway-IP-Address", .type = FR_TYPE_IPV4_ADDR, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_hardware_address_length, .name = "Hardware-Address-Length", .type = FR_TYPE_UINT8, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_hardware_type, .name = "Hardware-Type", .type = FR_TYPE_UINT8, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_hop_count, .name = "Hop-Count", .type = FR_TYPE_UINT8, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_number_of_seconds, .name = "Number-of-Seconds", .type = FR_TYPE_UINT16, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_opcode, .name = "Opcode", .type = FR_TYPE_UINT8, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_server_host_name, .name = "Server-Host-Name", .type = FR_TYPE_STRING, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_server_ip_address, .name = "Server-IP-Address", .type = FR_TYPE_IPV4_ADDR, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_transaction_id, .name = "Transaction-Id", .type = FR_TYPE_UINT32, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_your_ip_address, .name = "Your-IP-Address", .type = FR_TYPE_IPV4_ADDR, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_dhcp_maximum_msg_size, .name = "Maximum-Msg-Size", .type = FR_TYPE_UINT16, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_interface_mtu_size, .name = "Interface-MTU-Size", .type = FR_TYPE_UINT16, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_message_type, .name = "Message-Type", .type = FR_TYPE_UINT8, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_parameter_request_list, .name = "Parameter-Request-List", .type = FR_TYPE_UINT8, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_overload, .name = "Overload", .type = FR_TYPE_UINT8, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_vendor_class_identifier, .name = "Vendor-Class-Identifier", .type = FR_TYPE_OCTETS, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_relay_link_selection, .name = "Relay-Agent-Information.Relay-Link-Selection", .type = FR_TYPE_IPV4_ADDR, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_subnet_selection_option, .name = "Subnet-Selection-Option", .type = FR_TYPE_IPV4_ADDR, .dict = &dict_dhcpv4 },
        { .out = &attr_dhcp_network_subnet, .name = "Network-Subnet", .type = FR_TYPE_IPV4_PREFIX, .dict = &dict_dhcpv4 },
        { NULL }
};
 
/*
 *      INADDR_ANY : 68 -> INADDR_BROADCAST : 67        DISCOVER
 *      INADDR_BROADCAST : 68 <- SERVER_IP : 67         OFFER
 *      INADDR_ANY : 68 -> INADDR_BROADCAST : 67        REQUEST
 *      INADDR_BROADCAST : 68 <- SERVER_IP : 67         ACK
 */
fr_dict_attr_t const **dhcp_header_attrs[] = {
        &attr_dhcp_opcode,
        &attr_dhcp_hardware_type,
        &attr_dhcp_hardware_address_length,
        &attr_dhcp_hop_count,
        &attr_dhcp_transaction_id,
        &attr_dhcp_number_of_seconds,
        &attr_dhcp_flags,
        &attr_dhcp_client_ip_address,
        &attr_dhcp_your_ip_address,
        &attr_dhcp_server_ip_address,
        &attr_dhcp_gateway_ip_address,
        &attr_dhcp_client_hardware_address,
        &attr_dhcp_server_host_name,
        &attr_dhcp_boot_filename,
};
size_t dhcp_header_attrs_len = NUM_ELEMENTS(dhcp_header_attrs);
 
char const *dhcp_message_types[] = {
        "invalid",
        "Discover",
        "Offer",
        "Request",
        "Decline",
        "Ack",
        "NAK",
        "Release",
        "Inform",
        "Force-Renew",
        "Lease-Query",
        "Lease-Unassigned",
        "Lease-Unknown",
        "Lease-Active",
        "Bulk-Lease-Query",
        "Lease-Query-Done"
};
 
#define DHCP_MAX_MESSAGE_TYPE (NUM_ELEMENTS(dhcp_message_types))
 
int dhcp_header_sizes[] = {
        1,                      /* op */
        1,                      /* htype */
        1,                      /* hlen */
        1,                      /* hops */
        4,                      /* xid */
        2,                      /* secs */
        2,                      /* flags */
        4,                      /* ciaddr */
        4,                      /* yiaddr */
        4,                      /* siaddr */
        4,                      /* giaddr */
        DHCP_CHADDR_LEN,        /* chaddr */
        DHCP_SNAME_LEN,         /* sname */
        DHCP_FILE_LEN           /* file */
};
 
uint8_t eth_bcast[ETH_ADDR_LEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 
fr_dict_attr_t const *dhcp_option_82;
 
int8_t fr_dhcpv4_attr_cmp(void const *a, void const *b)
{
        fr_pair_t const *my_a = a, *my_b = b;
        fr_dict_attr_t const *a_82, *b_82;
 
        PAIR_VERIFY(my_a);
        PAIR_VERIFY(my_b);
 
        /*
         *      We can only use attribute numbers if we know they're
         *      not nested attributes.
         *
         *      @fixme We should be able to use my_a->da->parent->flags.is_root,
         *      but the DHCP attributes are hacked into the server under a vendor
         *      dictionary, so we can't.
         */
 
        /*
         *      Message-Type is first, for simplicity.
         */
        if (((my_a->da->parent->type != FR_TYPE_TLV) && (my_a->da == attr_dhcp_message_type)) &&
            ((my_b->da->parent->type == FR_TYPE_TLV) || (my_b->da != attr_dhcp_message_type))) return -1;
        if (((my_a->da->parent->type == FR_TYPE_TLV) || (my_a->da != attr_dhcp_message_type)) &&
            ((my_b->da->parent->type != FR_TYPE_TLV) && (my_b->da == attr_dhcp_message_type))) return +1;
 
        /*
         *      Relay-Agent is last.
         *
         *      Check if either of the options are descended from option 82.
         */
        a_82 = fr_dict_attr_common_parent(dhcp_option_82, my_a->da, true);
        b_82 = fr_dict_attr_common_parent(dhcp_option_82, my_b->da, true);
        if (a_82 && !b_82) return +1;
        if (!a_82 && !b_82) return -1;
 
        return fr_pair_cmp_by_parent_num(my_a, my_b);
}
 
/** Check received DHCP request is valid and build fr_packet_t structure if it is
 *
 * @param data pointer to received packet.
 * @param data_len length of received data, and then length of the actual DHCP data.
 * @param[out] message_type where the message type will be stored (if used)
 * @param[out] xid where the xid will be stored (if used)
 *
 * @return
 *      - true if the packet is well-formed
 *      - false if it's a bad packet
 */
bool fr_dhcpv4_ok(uint8_t const *data, ssize_t data_len, uint8_t *message_type, uint32_t *xid)
{
        uint32_t        magic;
        uint8_t const   *code;
        size_t          hlen;
 
        if (data_len < MIN_PACKET_SIZE) {
                fr_strerror_printf("DHCP packet is too small (%zu < %d)", data_len, MIN_PACKET_SIZE);
                return false;
        }
 
        if (data_len > MAX_PACKET_SIZE) {
                fr_strerror_printf("DHCP packet is too large (%zx > %d)", data_len, MAX_PACKET_SIZE);
                return false;
        }
 
        if (data[1] > 1) {
                fr_strerror_printf("DHCP can only process ethernet requests, not type %02x", data[1]);
                return false;
        }
 
        hlen = data[2];
        if ((hlen != 0) && (hlen != 6)) {
                fr_strerror_printf("Ethernet HW length incorrect.  Expected 6 got %zu", hlen);
                return false;
        }
 
        memcpy(&magic, data + 236, 4);
        magic = ntohl(magic);
        if (magic != DHCP_OPTION_MAGIC_NUMBER) {
                fr_strerror_const("BOOTP not supported");
                return false;
        }
 
        code = fr_dhcpv4_packet_get_option((dhcp_packet_t const *) data, data_len, attr_dhcp_message_type);
        if (!code || (code[1] == 0)) {
                fr_strerror_const("No message-type option was found in the packet");
                return false;
        }
 
        if ((code[2] == 0) || (code[2] >= DHCP_MAX_MESSAGE_TYPE)) {
                fr_strerror_printf("Unknown value %d for message-type option", code[2]);
                return false;
        }
 
        /*
         *      @todo - data_len MAY be larger than the data in the
         *      packet.  In which case, we should update data_len with
         *      the true size of the packet.
         */
 
        if (message_type) *message_type = code[2];
 
        if (xid) {
                memcpy(&magic, data + 4, 4);
                *xid = ntohl(magic);
        }
 
        return true;
}
 
/** Evaluation function for DCHPV4-encodability
 *
 * @param item  pointer to a fr_pair_t
 * @param uctx  context
 *
 * @return true if the underlying fr_pair_t is DHCPv4 encodable, false otherwise
 */
bool fr_dhcpv4_is_encodable(void const *item, UNUSED void const *uctx)
{
        fr_pair_t const *vp = item;
 
        PAIR_VERIFY(vp);
        return (vp->da->dict == dict_dhcpv4) && (!vp->da->flags.internal);
}
 
/** DHCPV4-specific iterator
 *
 */
void *fr_dhcpv4_next_encodable(fr_dlist_head_t *list, void *current, void *uctx)
{
        fr_pair_t       *c = current;
        fr_dict_t       *dict = talloc_get_type_abort(uctx, fr_dict_t);
 
        while ((c = fr_dlist_next(list, c))) {
                PAIR_VERIFY(c);
                if (c->da->dict != dict || c->da->flags.internal) continue;
 
                if (c->vp_type == FR_TYPE_BOOL && da_is_bool_exists(c->da) && !c->vp_bool) continue;
 
                break;
        }
 
        return c;
}
 
ssize_t fr_dhcpv4_encode(uint8_t *buffer, size_t buflen, dhcp_packet_t *original, int code, uint32_t xid, fr_pair_list_t *vps)
{
        return fr_dhcpv4_encode_dbuff(&FR_DBUFF_TMP(buffer, buflen), original, code, xid, vps);
}
 
ssize_t fr_dhcpv4_encode_dbuff(fr_dbuff_t *dbuff, dhcp_packet_t *original, int code, uint32_t xid, fr_pair_list_t *vps)
{
        fr_dcursor_t    cursor;
        fr_pair_t       *vp;
        ssize_t len;
        fr_dbuff_t      work_dbuff = FR_DBUFF(dbuff);
 
        /*
         *      @todo: Make this work again.
         */
#if 0
        mms = DEFAULT_PACKET_SIZE; /* maximum message size */
 
        /*
         *      Clients can request a LARGER size, but not a
         *      smaller one.  They also cannot request a size
         *      larger than MTU.
         */
 
        /* Maximum-Msg-Size */
        vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_dhcp_maximum_msg_size);
        if (vp && (vp->vp_uint32 > mms)) {
                mms = vp->vp_uint32;
 
                if (mms > MAX_PACKET_SIZE) mms = MAX_PACKET_SIZE;
        }
#endif
 
        vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_opcode);
        if (vp) {
                FR_DBUFF_IN_RETURN(&work_dbuff, vp->vp_uint8);
        } else {
                FR_DBUFF_IN_RETURN(&work_dbuff, (uint8_t)0x01); /* client message */
        }
 
        /* Hardware-Type */
        vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_hardware_type);
        if (vp) {
                FR_DBUFF_IN_RETURN(&work_dbuff, vp->vp_uint8);
 
        } else if (original) {
                FR_DBUFF_IN_RETURN(&work_dbuff, original->htype);
 
        } else { /* we are ALWAYS ethernet */
                FR_DBUFF_IN_RETURN(&work_dbuff, (uint8_t)0x01);
        }
 
        /* Hardware-Address-len */
        vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_hardware_address_length);
        if (vp) {
                FR_DBUFF_IN_RETURN(&work_dbuff, vp->vp_uint8);
 
        } else if (original) {
                FR_DBUFF_IN_RETURN(&work_dbuff, original->hlen);
 
        } else { /* we are ALWAYS ethernet */
                FR_DBUFF_IN_RETURN(&work_dbuff, (uint8_t)0x06);
        }
 
        /* Hop-Count */
        vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_hop_count);
        if (vp) {
                FR_DBUFF_IN_RETURN(&work_dbuff, vp->vp_uint8);
 
        } else if (original) {
                FR_DBUFF_IN_RETURN(&work_dbuff, original->hops);
 
        } else {
                FR_DBUFF_IN_RETURN(&work_dbuff, (uint8_t)0x00);
        }
 
        /* Transaction-Id */
        FR_DBUFF_IN_RETURN(&work_dbuff, xid);
 
        /* Number-of-Seconds */
        vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_number_of_seconds);
        if (vp) {
                FR_DBUFF_IN_RETURN(&work_dbuff, vp->vp_uint16);
        } else {
                FR_DBUFF_MEMSET_RETURN(&work_dbuff, 0, sizeof(vp->vp_uint16));
        }
 
        /* Flags */
        vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_flags);
        if (vp) {
                FR_DBUFF_IN_RETURN(&work_dbuff, vp->vp_uint16);
        } else {
                FR_DBUFF_MEMSET_RETURN(&work_dbuff, 0, sizeof(vp->vp_uint16));
        }
 
        /* Client-IP-Address */
        vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_client_ip_address);
        if (vp) {
                FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, (uint8_t const *)&vp->vp_ipv4addr, sizeof(vp->vp_ipv4addr));
        } else {
                FR_DBUFF_MEMSET_RETURN(&work_dbuff, 0, sizeof(vp->vp_ipv4addr));
        }
 
        /* Your-IP-address */
        vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_your_ip_address);
        if (vp) {
                FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, (uint8_t const *)&vp->vp_ipv4addr, sizeof(vp->vp_ipv4addr));
        } else {
                FR_DBUFF_IN_RETURN(&work_dbuff, (uint32_t) INADDR_ANY);
        }
 
        /* Server-IP-Address */
        vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_server_ip_address);
        if (vp) {
                FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, (uint8_t const *)&vp->vp_ipv4addr, sizeof(vp->vp_ipv4addr));
        } else {
                FR_DBUFF_IN_RETURN(&work_dbuff, (uint32_t) INADDR_ANY);
        }
 
        /*
         *      Gateway-IP-Address
         */
        vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_gateway_ip_address);
        if (vp) {
                FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, (uint8_t const *)&vp->vp_ipv4addr, sizeof(vp->vp_ipv4addr));
 
        } else if (original) {  /* copy whatever value was in the original */
                FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, (uint8_t const *)&original->giaddr, sizeof(original->giaddr));
 
        } else {
                FR_DBUFF_IN_RETURN(&work_dbuff, (uint32_t) INADDR_ANY);
        }
 
        /* Client-Hardware-Address */
        if ((vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_client_hardware_address))) {
                FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, (uint8_t const *)vp->vp_ether, sizeof(vp->vp_ether));
                FR_DBUFF_MEMSET_RETURN(&work_dbuff, 0, DHCP_CHADDR_LEN - sizeof(vp->vp_ether));
 
        } else if (original) {  /* copy whatever value was in the original */
                FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, &original->chaddr[0], sizeof(original->chaddr));
 
        } else {
                FR_DBUFF_MEMSET_RETURN(&work_dbuff, 0, DHCP_CHADDR_LEN);
        }
 
        /* Server-Host-Name */
        if ((vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_server_host_name))) {
                if (vp->vp_length > DHCP_SNAME_LEN) {
                        FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, vp->vp_strvalue, DHCP_SNAME_LEN);
                } else {
                        FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, vp->vp_strvalue, vp->vp_length);
                        FR_DBUFF_MEMSET_RETURN(&work_dbuff, 0, DHCP_SNAME_LEN - vp->vp_length);
                }
        } else {
                FR_DBUFF_MEMSET_RETURN(&work_dbuff, 0, DHCP_SNAME_LEN);
        }
 
        /*
         *      Copy over Boot-Filename.
         *
         *      FIXME: This copy should be delayed until AFTER the options
         *      have been processed.  If there are too many options for
         *      the packet, then they go into the sname && filename fields.
         *      When that happens, the boot filename is passed as an option,
         *      instead of being placed verbatim in the filename field.
         */
 
        /* Boot-Filename */
        if ((vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_boot_filename))) {
                if (vp->vp_length > DHCP_FILE_LEN) {
                        FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, vp->vp_strvalue, DHCP_FILE_LEN);
                } else {
                        FR_DBUFF_IN_MEMCPY_RETURN(&work_dbuff, vp->vp_strvalue, vp->vp_length);
                        FR_DBUFF_MEMSET_RETURN(&work_dbuff, 0, DHCP_FILE_LEN - vp->vp_length);
                }
        } else {
                FR_DBUFF_MEMSET_RETURN(&work_dbuff, 0, DHCP_FILE_LEN);
        }
 
        /* DHCP magic number */
        FR_DBUFF_IN_RETURN(&work_dbuff, (uint32_t) DHCP_OPTION_MAGIC_NUMBER);
 
        if ((vp = fr_pair_find_by_da(vps, NULL, attr_dhcp_message_type))) {
                FR_DBUFF_IN_BYTES_RETURN(&work_dbuff, FR_MESSAGE_TYPE, 0x01, vp->vp_uint8);
        } else {
                FR_DBUFF_IN_BYTES_RETURN(&work_dbuff, FR_MESSAGE_TYPE, 0x01, (uint8_t)code);
        }
 
        /*
         *  Pre-sort attributes into contiguous blocks so that fr_dhcpv4_encode_option
         *  operates correctly. This changes the order of the list, but never mind...
         */
        fr_pair_list_sort(vps, fr_dhcpv4_attr_cmp);
        fr_pair_dcursor_iter_init(&cursor, vps, fr_dhcpv4_next_encodable, dict_dhcpv4);
 
        /*
         *  Each call to fr_dhcpv4_encode_option will encode one complete DHCP option,
         *  and sub options.
         */
        while ((vp = fr_dcursor_current(&cursor))) {
                /*
                 *      The encoder skips message type, and returns
                 *      "len==0" for it.  We want to allow that, BUT
                 *      stop when the encoder returns "len==0" for
                 *      other attributes.  So we need to skip it
                 *      manually, too.
                 */
                if (vp->da == attr_dhcp_message_type) {
                        (void) fr_dcursor_next(&cursor);
                        continue;
                }
 
                len = fr_dhcpv4_encode_option(&work_dbuff,
                                              &cursor, &(fr_dhcpv4_ctx_t){ .root = fr_dict_root(dict_dhcpv4) });
                if (len <= 0) break;
        }
 
        FR_DBUFF_IN_BYTES_RETURN(&work_dbuff, FR_END_OF_OPTIONS, 0x00);
 
        /*
         *      FIXME: if (fr_dbuff_used(&work_dbuff) > mms),
         *        then we put the extra options into the "sname" and "file"
         *        fields, AND set the "end option option" in the "options"
         *        field.  We also set the "overload option",
         *        and put options into the "file" field, followed by
         *        the "sname" field.  Where each option is completely
         *        enclosed in the "file" and/or "sname" field, AND
         *        followed by the "end of option", and MUST be followed
         *        by padding option.
         *
         *      Yuck.  That sucks...
         */
        if (fr_dbuff_used(&work_dbuff) < DEFAULT_PACKET_SIZE) {
                FR_DBUFF_MEMSET_RETURN(&work_dbuff, 0, DEFAULT_PACKET_SIZE - fr_dbuff_used(&work_dbuff));
        }
 
        return fr_dbuff_set(dbuff, fr_dbuff_used(&work_dbuff));
}
 
 
/** Resolve/cache attributes in the DHCP dictionary
 *
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
int fr_dhcpv4_global_init(void)
{
        fr_value_box_t          value = *fr_box_uint8(0);
        uint8_t                 i;
 
        if (instance_count > 0) {
                instance_count++;
                return 0;
        }
 
        instance_count++;
 
        if (fr_dict_autoload(dhcpv4_dict) < 0) {
        fail:
                instance_count--;
                return -1;
        }
 
        if (fr_dict_attr_autoload(dhcpv4_dict_attr) < 0) {
                fr_dict_autofree(dhcpv4_dict);
                goto fail;
        }
 
        /*
         *      Fixup dictionary entry for Paramter-Request-List adding all the options
         */
        for (i = 1; i < 255; i++) {
                fr_dict_attr_t const *attr;
 
                attr = fr_dict_attr_child_by_num(fr_dict_root(dict_dhcpv4), i);
                if (!attr) {
                        continue;
                }
                value.vb_uint8 = i;
 
                if (fr_dict_enum_add_name(fr_dict_attr_unconst(attr_dhcp_parameter_request_list),
                                          attr->name, &value, true, false) < 0) {
                        goto fail;
                }
        }
 
        return 0;
}
 
void fr_dhcpv4_global_free(void)
{
        fr_assert(instance_count > 0);
 
        if (--instance_count > 0) return;
 
        fr_dict_autofree(dhcpv4_dict);
}
 
 
static char const *short_header_names[] = {
        "opcode",
        "hwtype",
        "hwaddrlen",
        "hop_count",
        "xid",
        "seconds",
        "flags",
        "ciaddr",
        "yiaddr",
        "siaddr",
        "giaddr",
        "chaddr",
        "server_hostname",
        "boot_filename",
};
 
static void print_hex_data(FILE *fp, 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(fp, "%.*s", depth, tabs);
                fprintf(fp, "%02x ", ptr[i]);
                if ((i & 0x0f) == 0x0f) fprintf(fp, "\n");
        }
        if ((i & 0x0f) != 0) fprintf(fp, "\n");
}
 
/** Print a raw DHCP packet as hex.
 *
 */
void fr_dhcpv4_print_hex(FILE *fp, uint8_t const *packet, size_t packet_len)
{
        int i;
        uint8_t const *attr, *end;
 
        end = packet + packet_len;
        attr = packet;
 
        for (i = 0; i < 14; i++) {
                fprintf(fp, "\t%s: ", short_header_names[i]);
                print_hex_data(fp, attr, dhcp_header_sizes[i], 2);
                attr += dhcp_header_sizes[i];
        }
 
        fprintf(fp, "\tmagic:\t%02x %02x %02x %02x\n", attr[0], attr[1], attr[2], attr[3]);
        attr += 4;
 
        fprintf(fp, "\toptions\n");
        while (attr < end) {
                fprintf(fp, "\t\t");
 
                fprintf(fp, "%02x  %02x  ", attr[0], attr[1]);
 
                print_hex_data(fp, attr + 2, attr[1], 3);
 
                /*
                 *      "End of option" option.
                 */
                if (attr[0] == 255) break;
 
                attr += attr[1] + 2;
        }
 
        fprintf(fp, "\n");
}
 
static fr_table_num_ordered_t const subtype_table[] = {
        { L("dns_label"),                       FLAG_ENCODE_DNS_LABEL },
        { L("encode=dns_label"),                FLAG_ENCODE_DNS_LABEL },
        { L("prefix=split"),                    FLAG_ENCODE_SPLIT_PREFIX },
        { L("prefix=bits"),                     FLAG_ENCODE_BITS_PREFIX },
        { L("encode=exists"),                   FLAG_ENCODE_BOOL_EXISTS },
};
 
static bool attr_valid(UNUSED fr_dict_t *dict, UNUSED fr_dict_attr_t const *parent,
                       UNUSED char const *name, UNUSED int attr, fr_type_t type, fr_dict_attr_flags_t *flags)
{
        /*
         *      "arrays" of string/octets are encoded as a 8-bit
         *      length, followed by the actual data.
         */
        if (flags->array && ((type == FR_TYPE_STRING) || (type == FR_TYPE_OCTETS))) {
                flags->is_known_width = true;
 
                if (flags->extra && (flags->subtype != FLAG_LENGTH_UINT8)) {
                        fr_strerror_const("string/octets arrays require the 'length=uint8' flag");
                        return false;
                }
        }
 
        if (flags->extra && (flags->subtype == FLAG_LENGTH_UINT16)) {
                fr_strerror_const("The 'length=uint16' flag cannot be used for DHCPv4");
                return false;
        }
 
        /*
         *      "extra" signifies that subtype is being used by the
         *      dictionaries itself.
         */
        if (flags->extra || !flags->subtype) return true;
 
        if ((type != FR_TYPE_STRING) && (flags->subtype == FLAG_ENCODE_DNS_LABEL)) {
                fr_strerror_const("The 'dns_label' flag can only be used with attributes of type 'string'");
                return false;
        }
 
        if ((type != FR_TYPE_IPV4_PREFIX) &&
            ((flags->subtype == FLAG_ENCODE_SPLIT_PREFIX) || (flags->subtype == FLAG_ENCODE_BITS_PREFIX))) {
                fr_strerror_const("The 'prefix=...' flag can only be used with attributes of type 'ipv4prefix'");
                return false;
        }
 
        if ((type != FR_TYPE_BOOL) && (flags->subtype == FLAG_ENCODE_BOOL_EXISTS)) {
                fr_strerror_const("The 'encode=exists' flag can only be used with attributes of type 'bool'");
                return false;
        }
 
        return true;
}
 
extern fr_dict_protocol_t libfreeradius_dhcpv4_dict_protocol;
fr_dict_protocol_t libfreeradius_dhcpv4_dict_protocol = {
        .name = "dhcpv4",
        .default_type_size = 1,
        .default_type_length = 1,
        .subtype_table = subtype_table,
        .subtype_table_len = NUM_ELEMENTS(subtype_table),
        .attr_valid = attr_valid,
 
        .init = fr_dhcpv4_global_init,
        .free = fr_dhcpv4_global_free,
 
        .encode         = fr_dhcpv4_encode_foreign,
        .decode         = fr_dhcpv4_decode_foreign,
};