Archipelago » qemu

/*

 * QEMU BOOTP/DHCP server

 *

 * Copyright (c) 2004 Fabrice Bellard

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

#include <slirp.h>

/* XXX: only DHCP is supported */

#define NB_ADDR 16

#define START_ADDR 15

#define LEASE_TIME (24 * 3600)

typedef struct {

    uint8_t allocated;

    uint8_t macaddr[6];

} BOOTPClient;

static BOOTPClient bootp_clients[NB_ADDR];

const char *bootp_filename;

static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };

#ifdef DEBUG

#define dprintf(fmt, args...) \

if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## args); fflush(dfd); }

#else

#define dprintf(fmt, args...)

#endif

static BOOTPClient *get_new_addr(struct in_addr *paddr)

{

    BOOTPClient *bc;

    int i;

    for(i = 0; i < NB_ADDR; i++) {

        if (!bootp_clients[i].allocated)

            goto found;

    }

    return NULL;

 found:

    bc = &bootp_clients[i];

    bc->allocated = 1;

    paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));

    return bc;

}

static BOOTPClient *request_addr(const struct in_addr *paddr,

                                 const uint8_t *macaddr)

{

    uint32_t req_addr = ntohl(paddr->s_addr);

    uint32_t spec_addr = ntohl(special_addr.s_addr);

    BOOTPClient *bc;

    if (req_addr >= (spec_addr | START_ADDR) &&

        req_addr < (spec_addr | (NB_ADDR + START_ADDR))) {

        bc = &bootp_clients[(req_addr & 0xff) - START_ADDR];

        if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6)) {

            bc->allocated = 1;

            return bc;

        }

    }

    return NULL;

}

static BOOTPClient *find_addr(struct in_addr *paddr, const uint8_t *macaddr)

{

    BOOTPClient *bc;

    int i;

    for(i = 0; i < NB_ADDR; i++) {

        if (!memcmp(macaddr, bootp_clients[i].macaddr, 6))

            goto found;

    }

    return NULL;

 found:

    bc = &bootp_clients[i];

    bc->allocated = 1;

    paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));

    return bc;

}

static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,

                        const struct in_addr **preq_addr)

{

    const uint8_t *p, *p_end;

    int len, tag;

    *pmsg_type = 0;

    *preq_addr = NULL;

    p = bp->bp_vend;

    p_end = p + DHCP_OPT_LEN;

    if (memcmp(p, rfc1533_cookie, 4) != 0)

        return;

    p += 4;

    while (p < p_end) {

        tag = p[0];

        if (tag == RFC1533_PAD) {

            p++;

        } else if (tag == RFC1533_END) {

            break;

        } else {

            p++;

            if (p >= p_end)

                break;

            len = *p++;

            dprintf("dhcp: tag=%d len=%d\n", tag, len);

            switch(tag) {

            case RFC2132_MSG_TYPE:

                if (len >= 1)

                    *pmsg_type = p[0];

                break;

            case RFC2132_REQ_ADDR:

                if (len >= 4)

                    *preq_addr = (struct in_addr *)p;

                break;

            default:

                break;

            }

            p += len;

        }

    }

    if (*pmsg_type == DHCPREQUEST && !*preq_addr && bp->bp_ciaddr.s_addr) {

        *preq_addr = &bp->bp_ciaddr;

    }

}

static void bootp_reply(const struct bootp_t *bp)

{

    BOOTPClient *bc = NULL;

    struct mbuf *m;

    struct bootp_t *rbp;

    struct sockaddr_in saddr, daddr;

    struct in_addr dns_addr;

    const struct in_addr *preq_addr;

    int dhcp_msg_type, val;

    uint8_t *q;

    /* extract exact DHCP msg type */

    dhcp_decode(bp, &dhcp_msg_type, &preq_addr);

    dprintf("bootp packet op=%d msgtype=%d", bp->bp_op, dhcp_msg_type);

    if (preq_addr)

        dprintf(" req_addr=%08x\n", ntohl(preq_addr->s_addr));

    else

        dprintf("\n");

    if (dhcp_msg_type == 0)

        dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */

    if (dhcp_msg_type != DHCPDISCOVER &&

        dhcp_msg_type != DHCPREQUEST)

        return;

    /* XXX: this is a hack to get the client mac address */

    memcpy(client_ethaddr, bp->bp_hwaddr, 6);

    if ((m = m_get()) == NULL)

        return;

    m->m_data += IF_MAXLINKHDR;

    rbp = (struct bootp_t *)m->m_data;

    m->m_data += sizeof(struct udpiphdr);

    memset(rbp, 0, sizeof(struct bootp_t));

    if (dhcp_msg_type == DHCPDISCOVER) {

        if (preq_addr) {

            bc = request_addr(preq_addr, client_ethaddr);

            if (bc) {

                daddr.sin_addr = *preq_addr;

            }

        }

        if (!bc) {

         new_addr:

            bc = get_new_addr(&daddr.sin_addr);

            if (!bc) {

                dprintf("no address left\n");

                return;

            }

        }

        memcpy(bc->macaddr, client_ethaddr, 6);

    } else if (preq_addr) {

        bc = request_addr(preq_addr, client_ethaddr);

        if (bc) {

            daddr.sin_addr = *preq_addr;

            memcpy(bc->macaddr, client_ethaddr, 6);

        } else {

            daddr.sin_addr.s_addr = 0;

        }

    } else {

        bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);

        if (!bc) {

            /* if never assigned, behaves as if it was already

               assigned (windows fix because it remembers its address) */

            goto new_addr;

        }

    }

    saddr.sin_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_ALIAS);

    saddr.sin_port = htons(BOOTP_SERVER);

    daddr.sin_port = htons(BOOTP_CLIENT);

    rbp->bp_op = BOOTP_REPLY;

    rbp->bp_xid = bp->bp_xid;

    rbp->bp_htype = 1;

    rbp->bp_hlen = 6;

    memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);

    rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */

    rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */

    q = rbp->bp_vend;

    memcpy(q, rfc1533_cookie, 4);

    q += 4;

    if (bc) {

        dprintf("%s addr=%08x\n",

                (dhcp_msg_type == DHCPDISCOVER) ? "offered" : "ack'ed",

                ntohl(daddr.sin_addr.s_addr));

        if (dhcp_msg_type == DHCPDISCOVER) {

            *q++ = RFC2132_MSG_TYPE;

            *q++ = 1;

            *q++ = DHCPOFFER;

        } else /* DHCPREQUEST */ {

            *q++ = RFC2132_MSG_TYPE;

            *q++ = 1;

            *q++ = DHCPACK;

        }

        if (bootp_filename)

            snprintf((char *)rbp->bp_file, sizeof(rbp->bp_file), "%s",

                     bootp_filename);

        *q++ = RFC2132_SRV_ID;

        *q++ = 4;

        memcpy(q, &saddr.sin_addr, 4);

        q += 4;

        *q++ = RFC1533_NETMASK;

        *q++ = 4;

        *q++ = 0xff;

        *q++ = 0xff;

        *q++ = 0xff;

        *q++ = 0x00;

        if (!slirp_restrict) {

            *q++ = RFC1533_GATEWAY;

            *q++ = 4;

            memcpy(q, &saddr.sin_addr, 4);

            q += 4;

            *q++ = RFC1533_DNS;

            *q++ = 4;

            dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_DNS);

            memcpy(q, &dns_addr, 4);

            q += 4;

        }

        *q++ = RFC2132_LEASE_TIME;

        *q++ = 4;

        val = htonl(LEASE_TIME);

        memcpy(q, &val, 4);

        q += 4;

        if (*slirp_hostname) {

            val = strlen(slirp_hostname);

            *q++ = RFC1533_HOSTNAME;

            *q++ = val;

            memcpy(q, slirp_hostname, val);

            q += val;

        }

    } else {

        static const char nak_msg[] = "requested address not available";

        dprintf("nak'ed addr=%08x\n", ntohl(preq_addr->s_addr));

        *q++ = RFC2132_MSG_TYPE;

        *q++ = 1;

        *q++ = DHCPNAK;

        *q++ = RFC2132_MESSAGE;

        *q++ = sizeof(nak_msg) - 1;

        memcpy(q, nak_msg, sizeof(nak_msg) - 1);

        q += sizeof(nak_msg) - 1;

    }

    *q++ = RFC1533_END;

    daddr.sin_addr.s_addr = 0xffffffffu;

    m->m_len = sizeof(struct bootp_t) -

        sizeof(struct ip) - sizeof(struct udphdr);

    udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);

}

void bootp_input(struct mbuf *m)

{

    struct bootp_t *bp = mtod(m, struct bootp_t *);

    if (bp->bp_op == BOOTP_REQUEST) {

        bootp_reply(bp);

    }

}