/////////////////////////////////////////////////////////////////////////
// $Id: bootp.cc 13203 2017-04-21 15:28:25Z vruppert $
/////////////////////////////////////////////////////////////////////////
/*
 * BOOTP/DHCP server (ported from Qemu)
 * Bochs additions: parameter list and some other options
 *
 * 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"

#if BX_NETWORKING && BX_NETMOD_SLIRP

/* XXX: only DHCP is supported */

#define LEASE_TIME (24 * 3600)

typedef struct {
    int msg_type;
    bx_bool found_srv_id;
    struct in_addr req_addr;
    uint8_t *params;
    uint8_t params_len;
    char *hostname;
    uint32_t lease_time;
} dhcp_options_t;

static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };

#ifdef DEBUG
#define DPRINTF(fmt, ...) \
do if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ##  __VA_ARGS__); fflush(dfd); } while (0)
#else
#define DPRINTF(fmt, ...) do{}while(0)
#endif

static BOOTPClient *get_new_addr(Slirp *slirp, struct in_addr *paddr,
                                 const uint8_t *macaddr)
{
    BOOTPClient *bc;
    int i;

    for(i = 0; i < NB_BOOTP_CLIENTS; i++) {
        bc = &slirp->bootp_clients[i];
        if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6))
            goto found;
    }
    return NULL;
 found:
    bc = &slirp->bootp_clients[i];
    bc->allocated = 1;
    paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i);
    return bc;
}

static BOOTPClient *request_addr(Slirp *slirp, const struct in_addr *paddr,
                                 const uint8_t *macaddr)
{
    uint32_t req_addr = ntohl(paddr->s_addr);
    uint32_t dhcp_addr = ntohl(slirp->vdhcp_startaddr.s_addr);
    BOOTPClient *bc;

    if (req_addr >= dhcp_addr &&
        req_addr < (dhcp_addr + NB_BOOTP_CLIENTS)) {
        bc = &slirp->bootp_clients[req_addr - dhcp_addr];
        if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6)) {
            bc->allocated = 1;
            return bc;
        }
    }
    return NULL;
}

static BOOTPClient *find_addr(Slirp *slirp, struct in_addr *paddr,
                              const uint8_t *macaddr)
{
    BOOTPClient *bc;
    int i;

    for(i = 0; i < NB_BOOTP_CLIENTS; i++) {
        if (!memcmp(macaddr, slirp->bootp_clients[i].macaddr, 6))
            goto found;
    }
    return NULL;
 found:
    bc = &slirp->bootp_clients[i];
    bc->allocated = 1;
    paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i);
    return bc;
}

static void dhcp_decode(Slirp *slirp, const struct bootp_t *bp, dhcp_options_t *opts)
{
    const uint8_t *p, *p_end;
    uint16_t defsize, maxsize;
    int len, tag;
    char msg[80];

    memset(opts, 0, sizeof(dhcp_options_t));

    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)
                    opts->msg_type = p[0];
                break;
              case RFC2132_REQ_ADDR:
                if (len >= 4) {
                    memcpy(&(opts->req_addr.s_addr), p, 4);
                }
                break;
              case RFC2132_SRV_ID:
                if (len >= 4) {
                    if (!memcmp(p, &slirp->vhost_addr, 4)) {
                        opts->found_srv_id = 1;
                    }
                }
                break;
              case RFC2132_PARAM_LIST:
                if (len >= 1) {
                    opts->params = (uint8_t*)malloc(len);
                    memcpy(opts->params, p, len);
                    opts->params_len = len;
                }
                break;
              case RFC1533_HOSTNAME:
                if (len >= 1) {
                    opts->hostname = (char*)malloc(len + 1);
                    memcpy(opts->hostname, p, len);
                    opts->hostname[len] = 0;
                }
                break;
              case RFC2132_LEASE_TIME:
                if (len == 4) {
                    memcpy(&opts->lease_time, p, len);
                }
                break;
              case RFC2132_MAX_SIZE:
                if (len == 2) {
                    memcpy(&maxsize, p, len);
                    defsize = sizeof(struct bootp_t) - sizeof(struct ip) - sizeof(struct udphdr);
                    if (ntohs(maxsize) < defsize) {
                        sprintf(msg, "DHCP server: RFB2132_MAX_SIZE=%u not supported yet", ntohs(maxsize));
                        slirp_warning(slirp, msg);
                    }
                }
                break;
              default:
                sprintf(msg, "DHCP server: option %d not supported yet", tag);
                slirp_warning(slirp, msg);
                break;
            }
            p += len;
        }
    }
    if ((opts->msg_type == DHCPREQUEST) && (opts->req_addr.s_addr == htonl(0L)) &&
        bp->bp_ciaddr.s_addr) {
        memcpy(&(opts->req_addr.s_addr), &bp->bp_ciaddr, 4);
    }
}

static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
{
    BOOTPClient *bc = NULL;
    struct mbuf *m;
    struct bootp_t *rbp;
    struct sockaddr_in saddr, daddr;
    struct in_addr bcast_addr;
    int val;
    uint8_t *q, *pp, plen, dhcp_def_params_len;
    uint8_t client_ethaddr[ETH_ALEN];
    uint8_t dhcp_def_params[8];
    bx_bool dhcp_def_params_valid = 0;
    dhcp_options_t dhcp_opts;
    size_t spaceleft;
    char msg[80];

    /* extract exact DHCP msg type */
    dhcp_decode(slirp, bp, &dhcp_opts);
    DPRINTF("bootp packet op=%d msgtype=%d", bp->bp_op, dhcp_opts.msg_type);
    if (dhcp_opts.req_addr.s_addr != htonl(0L))
        DPRINTF(" req_addr=%08x\n", ntohl(dhcp_opts.req_addr.s_addr));
    else
        DPRINTF("\n");

    if (dhcp_opts.msg_type == 0)
        dhcp_opts.msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */

    if (dhcp_opts.msg_type != DHCPDISCOVER &&
        dhcp_opts.msg_type != DHCPREQUEST)
        return;

    /* Get client's hardware address from bootp request */
    memcpy(client_ethaddr, bp->bp_hwaddr, ETH_ALEN);

    m = m_get(slirp);
    if (!m) {
        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));
    dhcp_def_params_len = 0;

    if (dhcp_opts.msg_type == DHCPDISCOVER) {
        if (dhcp_opts.req_addr.s_addr != htonl(0L)) {
            bc = request_addr(slirp, &dhcp_opts.req_addr, client_ethaddr);
            if (bc) {
                daddr.sin_addr = dhcp_opts.req_addr;
            }
        }
        if (!bc) {
         new_addr:
            bc = get_new_addr(slirp, &daddr.sin_addr, client_ethaddr);
            if (!bc) {
                DPRINTF("no address left\n");
                return;
            }
        }
        memcpy(bc->macaddr, client_ethaddr, ETH_ALEN);
        dhcp_def_params[0] = RFC2132_LEASE_TIME;
        dhcp_def_params[1] = RFC2132_SRV_ID;
        dhcp_def_params_len = 2;
        if (*slirp->client_hostname || (dhcp_opts.hostname != NULL)) {
            dhcp_def_params[dhcp_def_params_len++] = RFC1533_HOSTNAME;
        }
        dhcp_def_params_valid = 1;
    } else if (dhcp_opts.req_addr.s_addr != htonl(0L)) {
        bc = request_addr(slirp, &dhcp_opts.req_addr, client_ethaddr);
        if (bc) {
            daddr.sin_addr = dhcp_opts.req_addr;
            memcpy(bc->macaddr, client_ethaddr, ETH_ALEN);
            dhcp_def_params[0] = RFC2132_LEASE_TIME;
            dhcp_def_params_len = 1;
            if (!dhcp_opts.found_srv_id) {
                dhcp_def_params[dhcp_def_params_len++] = RFC2132_SRV_ID;
            }
            dhcp_def_params_valid = 1;
        } else {
            /* DHCPNAKs should be sent to broadcast */
            daddr.sin_addr.s_addr = 0xffffffff;
        }
    } else {
        bc = find_addr(slirp, &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;
        }
    }

    /* Update ARP table for this IP address */
    arp_table_add(slirp, daddr.sin_addr.s_addr, client_ethaddr);

    saddr.sin_addr = slirp->vhost_addr;
    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, ETH_ALEN);

    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_opts.msg_type == DHCPDISCOVER) ? "offered" : "ack'ed",
                ntohl(daddr.sin_addr.s_addr));

        if (dhcp_opts.msg_type == DHCPDISCOVER) {
            *q++ = RFC2132_MSG_TYPE;
            *q++ = 1;
            *q++ = DHCPOFFER;
        } else /* DHCPREQUEST */ {
            *q++ = RFC2132_MSG_TYPE;
            *q++ = 1;
            *q++ = DHCPACK;
        }

        if (slirp->bootp_filename)
            snprintf((char *)rbp->bp_file, sizeof(rbp->bp_file), "%s",
                     slirp->bootp_filename);

        strcpy((char *)rbp->bp_sname, "slirp");

        pp = dhcp_opts.params;
        plen = dhcp_opts.params_len;
        while (1) {
            while (plen-- > 0) {
                spaceleft = sizeof(rbp->bp_vend) - (q - rbp->bp_vend);
                if (spaceleft < 6) break;
                switch (*pp++) {
                    case RFC1533_NETMASK:
                        *q++ = RFC1533_NETMASK;
                        *q++ = 4;
                        memcpy(q, &slirp->vnetwork_mask, 4);
                        q += 4;
                        break;
                    case RFC1533_GATEWAY:
                        if (!slirp->restricted) {
                            *q++ = RFC1533_GATEWAY;
                            *q++ = 4;
                            memcpy(q, &saddr.sin_addr, 4);
                            q += 4;
                        }
                        break;
                    case RFC1533_DNS:
                        if (!slirp->restricted) {
                            *q++ = RFC1533_DNS;
                            *q++ = 4;
                            memcpy(q, &slirp->vnameserver_addr, 4);
                            q += 4;
                        }
                        break;
                    case RFC1533_HOSTNAME:
                        val = 0;
                        if (*slirp->client_hostname) {
                            val = strlen(slirp->client_hostname);
                        } else if (dhcp_opts.hostname != NULL) {
                            val = strlen(dhcp_opts.hostname);
                        }
                        if ((val > 0) && (spaceleft >= (size_t)(val + 2))) {
                            *q++ = RFC1533_HOSTNAME;
                            *q++ = val;
                            if (*slirp->client_hostname) {
                                memcpy(q, slirp->client_hostname, val);
                            } else {
                                memcpy(q, dhcp_opts.hostname, val);
                            }
                            q += val;
                        }
                        if (dhcp_opts.hostname != NULL) {
                            free(dhcp_opts.hostname);
                            dhcp_opts.hostname = NULL;
                        }
                        break;
                    case RFC1533_INTBROADCAST:
                        *q++ = RFC1533_INTBROADCAST;
                        *q++ = 4;
                        bcast_addr.s_addr = slirp->vhost_addr.s_addr | ~slirp->vnetwork_mask.s_addr;
                        memcpy(q, &bcast_addr, 4);
                        q += 4;
                        break;
                    case RFC2132_LEASE_TIME:
                        *q++ = RFC2132_LEASE_TIME;
                        *q++ = 4;
                        if ((dhcp_opts.lease_time != 0) &&
                            (ntohl(dhcp_opts.lease_time) < LEASE_TIME)) {
                            memcpy(q, &dhcp_opts.lease_time, 4);
                        } else {
                            val = htonl(LEASE_TIME);
                            memcpy(q, &val, 4);
                        }
                        q += 4;
                        dhcp_opts.lease_time = 0;
                        break;
                    case RFC2132_SRV_ID:
                        *q++ = RFC2132_SRV_ID;
                        *q++ = 4;
                        memcpy(q, &saddr.sin_addr, 4);
                        q += 4;
                        break;
                    case RFC2132_RENEWAL_TIME:
                        *q++ = RFC2132_RENEWAL_TIME;
                        *q++ = 4;
                        val = htonl(600);
                        memcpy(q, &val, 4);
                        q += 4;
                        break;
                    case RFC2132_REBIND_TIME:
                        *q++ = RFC2132_REBIND_TIME;
                        *q++ = 4;
                        val = htonl(1800);
                        memcpy(q, &val, 4);
                        q += 4;
                        break;
                    default:
                        sprintf(msg, "DHCP server: requested parameter %u not supported yet",
                                *(pp-1));
                        slirp_warning(slirp, msg);
                }
            }
            if (!dhcp_def_params_valid) break;
            pp = dhcp_def_params;
            plen = dhcp_def_params_len;
            dhcp_def_params_valid = 0;
        }

        if (slirp->vdnssearch) {
            spaceleft = sizeof(rbp->bp_vend) - (q - rbp->bp_vend);
            val = slirp->vdnssearch_len;
            if (val + 1 > (int)spaceleft) {
                slirp_warning(slirp, "DHCP packet size exceeded, omitting domain-search option.");
            } else {
                memcpy(q, slirp->vdnssearch, val);
                q += val;
            }
        }
    } else {
        static const char nak_msg[] = "requested address not available";

        DPRINTF("nak'ed addr=%08x\n", ntohl(dhcp_opts.req_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;

    if (dhcp_opts.params != NULL) free(dhcp_opts.params);

    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(m->slirp, bp);
    }
}

#endif
