HelenOS sources

root/uspace/srv/net/dhcp/dhcp.c

DEFINITIONS

1. subnet_mask_decode
2. dhcp_uint32_decode
3. dhcp_send_discover
4. dhcp_send_request
5. dhcp_parse_reply
6. dhcp_cfg_create
7. dhcpsrv_links_init
8. dhcpsrv_link_find
9. dhcp_link_set_failed
10. dhcp_discover_proc
11. dhcpsrv_link_add
12. dhcpsrv_link_remove
13. dhcpsrv_discover
14. dhcpsrv_recv_offer
15. dhcpsrv_recv_ack
16. dhcpsrv_recv
17. dhcpsrv_discover_timeout
18. dhcpsrv_request_timeout

/*
 * Copyright (c) 2024 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup dhcp
 * @{
 */
/**
 * @file
 * @brief DHCP client
 */

#include <adt/list.h>
#include <bitops.h>
#include <byteorder.h>
#include <errno.h>
#include <str_error.h>
#include <fibril_synch.h>
#include <inet/addr.h>
#include <inet/eth_addr.h>
#include <inet/dnsr.h>
#include <inet/inetcfg.h>
#include <io/log.h>
#include <loc.h>
#include <rndgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <str.h>

#include "dhcp.h"
#include "dhcp_std.h"
#include "transport.h"

enum {
        /** In microseconds */
        dhcp_discover_timeout_val = 5 * 1000 * 1000,
        /** In microseconds */
        dhcp_request_timeout_val = 1 * 1000 * 1000,
        dhcp_discover_retries = 5,
        dhcp_request_retries = 3
};

#define MAX_MSG_SIZE 1024
static uint8_t msgbuf[MAX_MSG_SIZE];

/** List of registered links (of dhcp_link_t) */
static list_t dhcp_links;

bool inetcfg_inited = false;

static void dhcpsrv_discover_timeout(void *);
static void dhcpsrv_request_timeout(void *);

typedef enum {
        ds_bound,
        ds_fail,
        ds_init,
        ds_init_reboot,
        ds_rebinding,
        ds_renewing,
        ds_requesting,
        ds_selecting
} dhcp_state_t;

typedef struct {
        /** Message type */
        enum dhcp_msg_type msg_type;
        /** Offered address */
        inet_naddr_t oaddr;
        /** Server address */
        inet_addr_t srv_addr;
        /** Router address */
        inet_addr_t router;
        /** DNS server */
        inet_addr_t dns_server;
        /** Transaction ID */
        uint32_t xid;
} dhcp_offer_t;

typedef struct {
        /** Link to dhcp_links list */
        link_t links;
        /** Link service ID */
        service_id_t link_id;
        /** Link info */
        inet_link_info_t link_info;
        /** Transport */
        dhcp_transport_t dt;
        /** Transport timeout */
        fibril_timer_t *timeout;
        /** Number of retries */
        int retries_left;
        /** Link state */
        dhcp_state_t state;
        /** Last received offer */
        dhcp_offer_t offer;
        /** Random number generator */
        rndgen_t *rndgen;
} dhcp_link_t;

static void dhcpsrv_recv(void *, void *, size_t);

/** Decode subnet mask into subnet prefix length. */
static errno_t subnet_mask_decode(uint32_t mask, int *bits)
{
        int zbits;
        uint32_t nmask;

        if (mask == 0xffffffff) {
                *bits = 32;
                return EOK;
        }

        zbits = 1 + fnzb32(mask ^ 0xffffffff);
        nmask = BIT_RRANGE(uint32_t, zbits);

        if ((mask ^ nmask) != 0xffffffff) {
                /* The mask is not in the form 1**n,0**m */
                return EINVAL;
        }

        *bits = 32 - zbits;
        return EOK;
}

static uint32_t dhcp_uint32_decode(uint8_t *data)
{
        return
            ((uint32_t)data[0] << 24) |
            ((uint32_t)data[1] << 16) |
            ((uint32_t)data[2] << 8) |
            ((uint32_t)data[3]);
}

static errno_t dhcp_send_discover(dhcp_link_t *dlink)
{
        dhcp_hdr_t *hdr = (dhcp_hdr_t *)msgbuf;
        uint8_t *opt = msgbuf + sizeof(dhcp_hdr_t);
        uint32_t xid;
        errno_t rc;
        size_t i;

        rc = rndgen_uint32(dlink->rndgen, &xid);
        if (rc != EOK)
                return rc;

        memset(msgbuf, 0, MAX_MSG_SIZE);
        hdr->op = op_bootrequest;
        hdr->htype = 1; /* AHRD_ETHERNET */
        hdr->hlen = ETH_ADDR_SIZE;
        hdr->xid = host2uint32_t_be(xid);
        hdr->flags = host2uint16_t_be(flag_broadcast);

        eth_addr_encode(&dlink->link_info.mac_addr, hdr->chaddr);
        hdr->opt_magic = host2uint32_t_be(dhcp_opt_magic);

        i = 0;

        opt[i++] = opt_msg_type;
        opt[i++] = 1;
        opt[i++] = msg_dhcpdiscover;

        opt[i++] = opt_param_req_list;
        opt[i++] = 3;
        opt[i++] = 1; /* subnet mask */
        opt[i++] = 6; /* DNS server */
        opt[i++] = 3; /* router */

        opt[i++] = opt_end;

        return dhcp_send(&dlink->dt, msgbuf, sizeof(dhcp_hdr_t) + i);
}

static errno_t dhcp_send_request(dhcp_link_t *dlink, dhcp_offer_t *offer)
{
        dhcp_hdr_t *hdr = (dhcp_hdr_t *)msgbuf;
        uint8_t *opt = msgbuf + sizeof(dhcp_hdr_t);
        size_t i;

        memset(msgbuf, 0, MAX_MSG_SIZE);
        hdr->op = op_bootrequest;
        hdr->htype = 1; /* AHRD_ETHERNET */
        hdr->hlen = 6;
        hdr->xid = host2uint32_t_be(offer->xid);
        hdr->flags = host2uint16_t_be(flag_broadcast);
        eth_addr_encode(&dlink->link_info.mac_addr, hdr->chaddr);
        hdr->opt_magic = host2uint32_t_be(dhcp_opt_magic);

        i = 0;

        opt[i++] = opt_msg_type;
        opt[i++] = 1;
        opt[i++] = msg_dhcprequest;

        opt[i++] = opt_req_ip_addr;
        opt[i++] = 4;
        opt[i++] = offer->oaddr.addr >> 24;
        opt[i++] = (offer->oaddr.addr >> 16) & 0xff;
        opt[i++] = (offer->oaddr.addr >> 8) & 0xff;
        opt[i++] = offer->oaddr.addr & 0xff;

        opt[i++] = opt_server_id;
        opt[i++] = 4;
        opt[i++] = offer->srv_addr.addr >> 24;
        opt[i++] = (offer->srv_addr.addr >> 16) & 0xff;
        opt[i++] = (offer->srv_addr.addr >> 8) & 0xff;
        opt[i++] = offer->srv_addr.addr & 0xff;

        opt[i++] = opt_end;

        return dhcp_send(&dlink->dt, msgbuf, sizeof(dhcp_hdr_t) + i);
}

static errno_t dhcp_parse_reply(void *msg, size_t size, dhcp_offer_t *offer)
{
        dhcp_hdr_t *hdr = (dhcp_hdr_t *)msg;
        inet_addr_t yiaddr;
        inet_addr_t siaddr;
        inet_addr_t giaddr;
        uint32_t subnet_mask;
        bool have_subnet_mask = false;
        bool have_server_id = false;
        int subnet_bits;
        char *saddr;
        uint8_t opt_type, opt_len;
        uint8_t *msgb;
        errno_t rc;
        size_t i;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "Receive reply");
        memset(offer, 0, sizeof(*offer));

        inet_addr_set(uint32_t_be2host(hdr->yiaddr), &yiaddr);
        rc = inet_addr_format(&yiaddr, &saddr);
        if (rc != EOK)
                return rc;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "Your IP address: %s", saddr);
        free(saddr);

        inet_addr_set(uint32_t_be2host(hdr->siaddr), &siaddr);
        rc = inet_addr_format(&siaddr, &saddr);
        if (rc != EOK)
                return rc;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "Next server IP address: %s", saddr);
        free(saddr);

        inet_addr_set(uint32_t_be2host(hdr->giaddr), &giaddr);
        rc = inet_addr_format(&giaddr, &saddr);
        if (rc != EOK)
                return rc;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "Relay agent IP address: %s", saddr);
        free(saddr);

        inet_naddr_set(yiaddr.addr, 0, &offer->oaddr);
        offer->xid = uint32_t_be2host(hdr->xid);

        msgb = (uint8_t *)msg;

        i = sizeof(dhcp_hdr_t);
        while (i < size) {
                opt_type = msgb[i++];

                if (opt_type == opt_pad)
                        continue;
                if (opt_type == opt_end)
                        break;

                if (i >= size)
                        return EINVAL;

                opt_len = msgb[i++];

                if (i + opt_len > size)
                        return EINVAL;

                switch (opt_type) {
                case opt_subnet_mask:
                        if (opt_len != 4)
                                return EINVAL;
                        subnet_mask = dhcp_uint32_decode(&msgb[i]);
                        rc = subnet_mask_decode(subnet_mask, &subnet_bits);
                        if (rc != EOK)
                                return EINVAL;
                        offer->oaddr.prefix = subnet_bits;
                        have_subnet_mask = true;
                        break;
                case opt_msg_type:
                        if (opt_len != 1)
                                return EINVAL;
                        offer->msg_type = msgb[i];
                        break;
                case opt_server_id:
                        if (opt_len != 4)
                                return EINVAL;
                        inet_addr_set(dhcp_uint32_decode(&msgb[i]),
                            &offer->srv_addr);
                        have_server_id = true;
                        break;
                case opt_router:
                        if (opt_len != 4)
                                return EINVAL;
                        inet_addr_set(dhcp_uint32_decode(&msgb[i]),
                            &offer->router);
                        break;
                case opt_dns_server:
                        if (opt_len < 4 || opt_len % 4 != 0)
                                return EINVAL;
                        /* XXX Handle multiple DNS servers properly */
                        inet_addr_set(dhcp_uint32_decode(&msgb[i]),
                            &offer->dns_server);
                        break;
                case opt_end:
                        break;
                default:
                        break;
                }

                /* Advance to the next option */
                i = i + opt_len;
        }

        if (!have_server_id) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Missing server ID option.");
                return rc;
        }

        if (!have_subnet_mask) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Missing subnet mask option.");
                return rc;
        }

        rc = inet_naddr_format(&offer->oaddr, &saddr);
        if (rc != EOK)
                return rc;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "Offered network address: %s", saddr);
        free(saddr);

        if (offer->router.addr != 0) {
                rc = inet_addr_format(&offer->router, &saddr);
                if (rc != EOK)
                        return rc;

                log_msg(LOG_DEFAULT, LVL_DEBUG, "Router address: %s", saddr);
                free(saddr);
        }

        if (offer->dns_server.addr != 0) {
                rc = inet_addr_format(&offer->dns_server, &saddr);
                if (rc != EOK)
                        return rc;

                log_msg(LOG_DEFAULT, LVL_DEBUG, "DNS server: %s", saddr);
                free(saddr);
        }

        return EOK;
}

static errno_t dhcp_cfg_create(service_id_t iplink, dhcp_offer_t *offer)
{
        errno_t rc;
        service_id_t addr_id;
        service_id_t sroute_id;
        inet_naddr_t defr;

        rc = inetcfg_addr_create_static("dhcp4a", &offer->oaddr, iplink,
            &addr_id);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR,
                    "Error creating IP address %s: %s", "dhcp4a", str_error(rc));
                return rc;
        }

        if (offer->router.addr != 0) {
                inet_naddr_set(0, 0, &defr);

                rc = inetcfg_sroute_create("dhcpdef", &defr, &offer->router, &sroute_id);
                if (rc != EOK) {
                        log_msg(LOG_DEFAULT, LVL_ERROR, "Error creating "
                            "default route %s: %s.", "dhcpdef", str_error(rc));
                        return rc;
                }
        }

        if (offer->dns_server.addr != 0) {
                rc = dnsr_set_srvaddr(&offer->dns_server);
                if (rc != EOK) {
                        log_msg(LOG_DEFAULT, LVL_ERROR, "Error setting "
                            "nameserver address: %s)", str_error(rc));
                        return rc;
                }
        }

        return EOK;
}

void dhcpsrv_links_init(void)
{
        list_initialize(&dhcp_links);
}

static dhcp_link_t *dhcpsrv_link_find(service_id_t link_id)
{
        list_foreach(dhcp_links, links, dhcp_link_t, dlink) {
                if (dlink->link_id == link_id)
                        return dlink;
        }

        return NULL;
}

static void dhcp_link_set_failed(dhcp_link_t *dlink)
{
        log_msg(LOG_DEFAULT, LVL_NOTE, "Giving up on link %s",
            dlink->link_info.name);
        dlink->state = ds_fail;
}

static errno_t dhcp_discover_proc(dhcp_link_t *dlink)
{
        dlink->state = ds_selecting;

        errno_t rc = dhcp_send_discover(dlink);
        if (rc != EOK)
                return EIO;

        dlink->retries_left = dhcp_discover_retries;

        if ((dlink->timeout->state == fts_not_set) ||
            (dlink->timeout->state == fts_fired))
                fibril_timer_set(dlink->timeout, dhcp_discover_timeout_val,
                    dhcpsrv_discover_timeout, dlink);

        return rc;
}

errno_t dhcpsrv_link_add(service_id_t link_id)
{
        dhcp_link_t *dlink;
        errno_t rc;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "dhcpsrv_link_add(%zu)", link_id);

        if (!inetcfg_inited) {
                rc = inetcfg_init();
                if (rc != EOK) {
                        log_msg(LOG_DEFAULT, LVL_ERROR, "Error contacting "
                            "inet configuration service.\n");
                        return EIO;
                }

                inetcfg_inited = true;
        }

        if (dhcpsrv_link_find(link_id) != NULL) {
                log_msg(LOG_DEFAULT, LVL_NOTE, "Link %zu already added",
                    link_id);
                return EEXIST;
        }

        dlink = calloc(1, sizeof(dhcp_link_t));
        if (dlink == NULL)
                return ENOMEM;

        rc = rndgen_create(&dlink->rndgen);
        if (rc != EOK)
                goto error;

        dlink->link_id = link_id;
        dlink->timeout = fibril_timer_create(NULL);
        if (dlink->timeout == NULL) {
                rc = ENOMEM;
                goto error;
        }

        /* Get link hardware address */
        rc = inetcfg_link_get(link_id, &dlink->link_info);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Error getting properties "
                    "for link %zu.", link_id);
                rc = EIO;
                goto error;
        }

        rc = dhcp_transport_init(&dlink->dt, link_id, dhcpsrv_recv, dlink);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Error initializing DHCP "
                    "transport for link %s.", dlink->link_info.name);
                rc = EIO;
                goto error;
        }

        log_msg(LOG_DEFAULT, LVL_DEBUG, "Send DHCPDISCOVER");
        rc = dhcp_discover_proc(dlink);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Error sending DHCPDISCOVER.");
                dhcp_link_set_failed(dlink);
                rc = EIO;
                goto error;
        }

        list_append(&dlink->links, &dhcp_links);

        return EOK;
error:
        if (dlink != NULL && dlink->rndgen != NULL)
                rndgen_destroy(dlink->rndgen);
        if (dlink != NULL && dlink->timeout != NULL)
                fibril_timer_destroy(dlink->timeout);
        free(dlink);
        return rc;
}

errno_t dhcpsrv_link_remove(service_id_t link_id)
{
        return ENOTSUP;
}

errno_t dhcpsrv_discover(service_id_t link_id)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "dhcpsrv_link_add(%zu)", link_id);

        dhcp_link_t *dlink = dhcpsrv_link_find(link_id);

        if (dlink == NULL) {
                log_msg(LOG_DEFAULT, LVL_NOTE, "Link %zu doesn't exist",
                    link_id);
                return EINVAL;
        }

        return dhcp_discover_proc(dlink);
}

static void dhcpsrv_recv_offer(dhcp_link_t *dlink, dhcp_offer_t *offer)
{
        errno_t rc;

        if (dlink->state != ds_selecting) {
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Received offer in state "
                    " %d, ignoring.", (int)dlink->state);
                return;
        }

        fibril_timer_clear(dlink->timeout);
        dlink->offer = *offer;
        dlink->state = ds_requesting;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "Send DHCPREQUEST");
        rc = dhcp_send_request(dlink, offer);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Error sending request.");
                return;
        }

        dlink->retries_left = dhcp_request_retries;
        fibril_timer_set(dlink->timeout, dhcp_request_timeout_val,
            dhcpsrv_request_timeout, dlink);
}

static void dhcpsrv_recv_ack(dhcp_link_t *dlink, dhcp_offer_t *offer)
{
        errno_t rc;

        if (dlink->state != ds_requesting) {
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Received ack in state "
                    " %d, ignoring.", (int)dlink->state);
                return;
        }

        fibril_timer_clear(dlink->timeout);
        dlink->offer = *offer;
        dlink->state = ds_bound;

        rc = dhcp_cfg_create(dlink->link_id, offer);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Error creating configuration.");
                return;
        }

        log_msg(LOG_DEFAULT, LVL_NOTE, "%s: Successfully configured.",
            dlink->link_info.name);
}

static void dhcpsrv_recv(void *arg, void *msg, size_t size)
{
        dhcp_link_t *dlink = (dhcp_link_t *)arg;
        dhcp_offer_t offer;
        errno_t rc;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "%s: dhcpsrv_recv() %zu bytes",
            dlink->link_info.name, size);

        rc = dhcp_parse_reply(msg, size, &offer);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Error parsing reply");
                return;
        }

        switch (offer.msg_type) {
        case msg_dhcpoffer:
                dhcpsrv_recv_offer(dlink, &offer);
                break;
        case msg_dhcpack:
                dhcpsrv_recv_ack(dlink, &offer);
                break;
        default:
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Received unexpected "
                    "message type. %d", (int)offer.msg_type);
                break;
        }
}

static void dhcpsrv_discover_timeout(void *arg)
{
        dhcp_link_t *dlink = (dhcp_link_t *)arg;
        errno_t rc;

        assert(dlink->state == ds_selecting);
        log_msg(LOG_DEFAULT, LVL_NOTE, "%s: dhcpsrv_discover_timeout",
            dlink->link_info.name);

        if (dlink->retries_left == 0) {
                log_msg(LOG_DEFAULT, LVL_NOTE, "Retries exhausted");
                dhcp_link_set_failed(dlink);
                return;
        }
        --dlink->retries_left;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "Send DHCPDISCOVER");
        rc = dhcp_send_discover(dlink);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Error sending DHCPDISCOVER");
                dhcp_link_set_failed(dlink);
                return;
        }

        fibril_timer_set(dlink->timeout, dhcp_discover_timeout_val,
            dhcpsrv_discover_timeout, dlink);
}

static void dhcpsrv_request_timeout(void *arg)
{
        dhcp_link_t *dlink = (dhcp_link_t *)arg;
        errno_t rc;

        assert(dlink->state == ds_requesting);
        log_msg(LOG_DEFAULT, LVL_NOTE, "%s: dhcpsrv_request_timeout",
            dlink->link_info.name);

        if (dlink->retries_left == 0) {
                log_msg(LOG_DEFAULT, LVL_NOTE, "Retries exhausted");
                dhcp_link_set_failed(dlink);
                return;
        }
        --dlink->retries_left;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "Send DHCPREQUEST");
        rc = dhcp_send_request(dlink, &dlink->offer);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Error sending request.");
                dhcp_link_set_failed(dlink);
                return;
        }

        fibril_timer_set(dlink->timeout, dhcp_request_timeout_val,
            dhcpsrv_request_timeout, dlink);
}

/** @}
 */