xnu-517.3.15.tar.gz

[apple/xnu.git] / osfmk / kdp / kdp_udp.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1982, 1986, 1993
 *      The Regents of the University of California.  All rights reserved.
 */

/*
 * Kernel Debugging Protocol UDP implementation.
 */

#include <mach_kdb.h>
#include <mach/boolean.h>
#include <mach/mach_types.h>
#include <mach/exception_types.h>
#include <kern/cpu_data.h>
#include <kern/debug.h>

#include <kdp/kdp_internal.h>
#include <kdp/kdp_en_debugger.h>
#include <kdp/kdp_udp.h>

#include <kdp/kdp_core.h>

#include <vm/vm_map.h>
#include <mach/memory_object_types.h>

#include <string.h>

#define DO_ALIGN        1       /* align all packet data accesses */

extern int kdp_getc(void);
extern int reattach_wait;

static u_short ip_id;                          /* ip packet ctr, for ids */

/*      @(#)udp_usrreq.c        2.2 88/05/23 4.0NFSSRC SMI;     from UCB 7.1 6/5/86     */

/*
 * UDP protocol implementation.
 * Per RFC 768, August, 1980.
 */
#define UDP_TTL 60 /* deflt time to live for UDP packets */
int     udp_ttl = UDP_TTL;
static unsigned char    exception_seq;

static struct {
    unsigned char       data[KDP_MAXPACKET];
    unsigned int        off, len;
    boolean_t           input;
} pkt, saved_reply;

struct {
    struct {
        struct in_addr          in;
        struct ether_addr       ea;
    } loc;
    struct {
        struct in_addr          in;
        struct ether_addr       ea;
    } rmt;
} adr;

static char
*exception_message[] = {
    "Unknown",
    "Memory access",            /* EXC_BAD_ACCESS */
    "Failed instruction",       /* EXC_BAD_INSTRUCTION */
    "Arithmetic",               /* EXC_ARITHMETIC */
    "Emulation",                /* EXC_EMULATION */
    "Software",                 /* EXC_SOFTWARE */
    "Breakpoint"                /* EXC_BREAKPOINT */
};

int kdp_flag = 0;

static kdp_send_t kdp_en_send_pkt = 0;
static kdp_receive_t kdp_en_recv_pkt = 0;


static u_long kdp_current_ip_address = 0;
static struct ether_addr kdp_current_mac_address = {{0, 0, 0, 0, 0, 0}};
static void *kdp_current_ifp = 0;

static void kdp_handler( void *);

static unsigned int panic_server_ip = 0; 
static unsigned int parsed_router_ip = 0;
static unsigned int router_ip = 0;
static unsigned int panicd_specified = 0;
static unsigned int router_specified = 0;

static struct ether_addr router_mac = {{0, 0, 0 , 0, 0, 0}};

static u_char flag_panic_dump_in_progress = 0;
static u_char flag_router_mac_initialized = 0;

static unsigned int panic_timeout = 100000;
static unsigned int last_panic_port = CORE_REMOTE_PORT;

unsigned int SEGSIZE = 512;

static unsigned int PANIC_PKTSIZE = 518;
static char panicd_ip_str[20];
static char router_ip_str[20];

static unsigned int panic_block = 0;
static volatile unsigned int kdp_trigger_core_dump = 0;

extern unsigned int not_in_kdp;

void
kdp_register_send_receive(
        kdp_send_t      send, 
        kdp_receive_t   receive)
{
        unsigned int    debug;

        kdp_en_send_pkt = send;
        kdp_en_recv_pkt = receive;

        debug_log_init();

        PE_parse_boot_arg("debug", &debug);

        if (debug & DB_KDP_BP_DIS)
                kdp_flag |= KDP_BP_DIS;   
        if (debug & DB_KDP_GETC_ENA)
                kdp_flag |= KDP_GETC_ENA;   
        if (debug & DB_ARP)
          kdp_flag |= KDP_ARP;

        if (debug & DB_KERN_DUMP_ON_PANIC)
          kdp_flag |= KDP_PANIC_DUMP_ENABLED;
        if (debug & DB_KERN_DUMP_ON_NMI)
          kdp_flag |= PANIC_CORE_ON_NMI;
        
        if (debug & DB_DBG_POST_CORE)
          kdp_flag |= DBG_POST_CORE;
        
        if (debug & DB_PANICLOG_DUMP)
          kdp_flag |= PANIC_LOG_DUMP;
        
        if (PE_parse_boot_arg ("_panicd_ip", panicd_ip_str))
          panicd_specified = 1;
        /* For the future, currently non-functional */
        if (PE_parse_boot_arg ("_router_ip", router_ip_str))
          router_specified = 1;

        kdp_flag |= KDP_READY;
        if (current_debugger == NO_CUR_DB)
                current_debugger = KDP_CUR_DB;
        if (halt_in_debugger) {
                kdp_call(); 
                halt_in_debugger=0;
        }
}

void
kdp_unregister_send_receive(
        kdp_send_t              send, 
        kdp_receive_t   receive)
{
        if (current_debugger == KDP_CUR_DB)
                current_debugger = NO_CUR_DB;
        kdp_flag &= ~KDP_READY;
        kdp_en_send_pkt = NULL;
        kdp_en_recv_pkt = NULL;
}

static void
enaddr_copy(
        void    *src,
        void    *dst
)
{
        bcopy((char *)src, (char *)dst, sizeof (struct ether_addr));
}

static unsigned short
ip_sum(
        unsigned char   *c,
        unsigned int    hlen
)
{
    unsigned int        high, low, sum;
    
    high = low = 0;
    while (hlen-- > 0) {
        low += c[1] + c[3];
        high += c[0] + c[2];
        
        c += sizeof (int);
    }
    
    sum = (high << 8) + low;
    sum = (sum >> 16) + (sum & 65535);
    
    return (sum > 65535 ? sum - 65535 : sum);
}

static void
kdp_reply(
        unsigned short          reply_port
)
{
    struct udpiphdr             aligned_ui, *ui = &aligned_ui;
    struct ip                   aligned_ip, *ip = &aligned_ip;
    struct in_addr              tmp_ipaddr;
    struct ether_addr           tmp_enaddr;
    struct ether_header         *eh;
    
    if (!pkt.input)
        kdp_panic("kdp_reply");
        
    pkt.off -= sizeof (struct udpiphdr);

#if DO_ALIGN    
    bcopy((char *)&pkt.data[pkt.off], (char *)ui, sizeof(*ui));
#else
    ui = (struct udpiphdr *)&pkt.data[pkt.off];
#endif
    ui->ui_next = ui->ui_prev = 0;
    ui->ui_x1 = 0;
    ui->ui_pr = IPPROTO_UDP;
    ui->ui_len = htons((u_short)pkt.len + sizeof (struct udphdr));
    tmp_ipaddr = ui->ui_src;
    ui->ui_src = ui->ui_dst;
    ui->ui_dst = tmp_ipaddr;
    ui->ui_sport = htons(KDP_REMOTE_PORT);
    ui->ui_dport = reply_port;
    ui->ui_ulen = ui->ui_len;
    ui->ui_sum = 0;
#if DO_ALIGN
    bcopy((char *)ui, (char *)&pkt.data[pkt.off], sizeof(*ui));
    bcopy((char *)&pkt.data[pkt.off], (char *)ip, sizeof(*ip));
#else
    ip = (struct ip *)&pkt.data[pkt.off];
#endif
    ip->ip_len = htons(sizeof (struct udpiphdr) + pkt.len);
    ip->ip_v = IPVERSION;
    ip->ip_id = htons(ip_id++);
    ip->ip_hl = sizeof (struct ip) >> 2;
    ip->ip_ttl = udp_ttl;
    ip->ip_sum = 0;
    ip->ip_sum = htons(~ip_sum((unsigned char *)ip, ip->ip_hl));
#if DO_ALIGN
    bcopy((char *)ip, (char *)&pkt.data[pkt.off], sizeof(*ip));
#endif
    
    pkt.len += sizeof (struct udpiphdr);
    
    pkt.off -= sizeof (struct ether_header);
    
    eh = (struct ether_header *)&pkt.data[pkt.off];
    enaddr_copy(eh->ether_shost, &tmp_enaddr);
    enaddr_copy(eh->ether_dhost, eh->ether_shost);
    enaddr_copy(&tmp_enaddr, eh->ether_dhost);
    eh->ether_type = htons(ETHERTYPE_IP);
    
    pkt.len += sizeof (struct ether_header);
    
    // save reply for possible retransmission
    bcopy((char *)&pkt, (char *)&saved_reply, sizeof(pkt));

    (*kdp_en_send_pkt)(&pkt.data[pkt.off], pkt.len);

    // increment expected sequence number
    exception_seq++;
}

static void
kdp_send(
    unsigned short              remote_port
)
{
    struct udpiphdr             aligned_ui, *ui = &aligned_ui;
    struct ip                   aligned_ip, *ip = &aligned_ip;
    struct ether_header         *eh;
    
    if (pkt.input)
        kdp_panic("kdp_send");

    pkt.off -= sizeof (struct udpiphdr);

#if DO_ALIGN
    bcopy((char *)&pkt.data[pkt.off], (char *)ui, sizeof(*ui));
#else
    ui = (struct udpiphdr *)&pkt.data[pkt.off];
#endif
    ui->ui_next = ui->ui_prev = 0;
    ui->ui_x1 = 0;
    ui->ui_pr = IPPROTO_UDP;
    ui->ui_len = htons((u_short)pkt.len + sizeof (struct udphdr));
    ui->ui_src = adr.loc.in;
    ui->ui_dst = adr.rmt.in;
    ui->ui_sport = htons(KDP_REMOTE_PORT);
    ui->ui_dport = remote_port;
    ui->ui_ulen = ui->ui_len;
    ui->ui_sum = 0;
#if DO_ALIGN
    bcopy((char *)ui, (char *)&pkt.data[pkt.off], sizeof(*ui));
    bcopy((char *)&pkt.data[pkt.off], (char *)ip, sizeof(*ip));
#else
    ip = (struct ip *)&pkt.data[pkt.off];
#endif
    ip->ip_len = htons(sizeof (struct udpiphdr) + pkt.len);
    ip->ip_v = IPVERSION;
    ip->ip_id = htons(ip_id++);
    ip->ip_hl = sizeof (struct ip) >> 2;
    ip->ip_ttl = udp_ttl;
    ip->ip_sum = 0;
    ip->ip_sum = htons(~ip_sum((unsigned char *)ip, ip->ip_hl));
#if DO_ALIGN
    bcopy((char *)ip, (char *)&pkt.data[pkt.off], sizeof(*ip));
#endif
    
    pkt.len += sizeof (struct udpiphdr);
    
    pkt.off -= sizeof (struct ether_header);
    
    eh = (struct ether_header *)&pkt.data[pkt.off];
    enaddr_copy(&adr.loc.ea, eh->ether_shost);
    enaddr_copy(&adr.rmt.ea, eh->ether_dhost);
    eh->ether_type = htons(ETHERTYPE_IP);
    
    pkt.len += sizeof (struct ether_header);
    (*kdp_en_send_pkt)(&pkt.data[pkt.off], pkt.len);
}

/* We don't interpret this pointer, we just give it to the
bsd stack so it can decide when to set the MAC and IP info. */
void
kdp_set_interface(void *ifp)
{
        kdp_current_ifp = ifp;
}

void *
kdp_get_interface()
{
        return kdp_current_ifp;
}

void 
kdp_set_ip_and_mac_addresses(
        struct in_addr          *ipaddr, 
        struct ether_addr       *macaddr)
{
        unsigned int debug = 0;

        kdp_current_ip_address = ipaddr->s_addr;
        kdp_current_mac_address = *macaddr;
}

void
kdp_set_gateway_mac(void *gatewaymac)
{
  router_mac = *(struct ether_addr *)gatewaymac;
} 

struct ether_addr 
kdp_get_mac_addr(void)
{
  return kdp_current_mac_address;
}

unsigned int 
kdp_get_ip_address(void)
{
  return kdp_current_ip_address;
}

/* ARP responses are enabled when the DB_ARP bit of the debug boot arg
   is set. A workaround if you don't want to reboot is to set 
   kdpDEBUGFlag &= DB_ARP when connected (but that certainly isn't a published
   interface!)
*/
static void 
kdp_arp_reply(void)
{
        struct ether_header     *eh;
        struct ether_arp        aligned_ea, *ea = &aligned_ea;

        struct in_addr          isaddr, itaddr, myaddr;
        struct ether_addr       my_enaddr;

        eh = (struct ether_header *)&pkt.data[pkt.off];
        pkt.off += sizeof(struct ether_header);

        memcpy((void *)ea, (void *)&pkt.data[pkt.off],sizeof(*ea));
  
        if(ntohs(ea->arp_op) != ARPOP_REQUEST)
          return;

        myaddr.s_addr = kdp_get_ip_address();
        my_enaddr = kdp_get_mac_addr();

        if (!(myaddr.s_addr) || !(my_enaddr.ether_addr_octet[1]))
                return;

        (void)memcpy((void *)&isaddr, (void *)ea->arp_spa, sizeof (isaddr));
        (void)memcpy((void *)&itaddr, (void *)ea->arp_tpa, sizeof (itaddr));
  
        if (itaddr.s_addr == myaddr.s_addr) {
                (void)memcpy((void *)ea->arp_tha, (void *)ea->arp_sha, sizeof(ea->arp_sha));
                (void)memcpy((void *)ea->arp_sha, (void *)&my_enaddr, sizeof(ea->arp_sha));

                (void)memcpy((void *)ea->arp_tpa, (void *) ea->arp_spa, sizeof(ea->arp_spa));
                (void)memcpy((void *)ea->arp_spa, (void *) &itaddr, sizeof(ea->arp_spa));

                ea->arp_op = htons(ARPOP_REPLY);
                ea->arp_pro = htons(ETHERTYPE_IP); 
                (void)memcpy(eh->ether_dhost, ea->arp_tha, sizeof(eh->ether_dhost));
                (void)memcpy(eh->ether_shost, &my_enaddr, sizeof(eh->ether_shost));
                eh->ether_type = htons(ETHERTYPE_ARP);
                (void)memcpy(&pkt.data[pkt.off], ea, sizeof(*ea));
                pkt.off -= sizeof (struct ether_header);
                /* pkt.len is still the length we want, ether_header+ether_arp */
                (*kdp_en_send_pkt)(&pkt.data[pkt.off], pkt.len);
        }
}

static void
kdp_poll(void)
{
  struct ether_header   *eh;
  struct udpiphdr       aligned_ui, *ui = &aligned_ui;
  struct ip             aligned_ip, *ip = &aligned_ip;
  static int            msg_printed;


    if (pkt.input)
        kdp_panic("kdp_poll");
 
    if (!kdp_en_recv_pkt || !kdp_en_send_pkt) {
        if( msg_printed == 0) {
            msg_printed = 1;
            printf("kdp_poll: no debugger device\n");
        }
        return;
    }

    pkt.off = pkt.len = 0;
    (*kdp_en_recv_pkt)(pkt.data, &pkt.len, 3/* ms */);
  
    if (pkt.len == 0)
        return;

    if (pkt.len >= sizeof(struct ether_header))
      {
        eh = (struct ether_header *)&pkt.data[pkt.off];  
        
        if (kdp_flag & KDP_ARP)
          {
            if (ntohs(eh->ether_type) == ETHERTYPE_ARP)
              {
                kdp_arp_reply();
                return;
              }
          }
      }

    if (pkt.len < (sizeof (struct ether_header) + sizeof (struct udpiphdr)))
        return;

    pkt.off += sizeof (struct ether_header);
    if (ntohs(eh->ether_type) != ETHERTYPE_IP) {
        return;
    }

#if DO_ALIGN
    bcopy((char *)&pkt.data[pkt.off], (char *)ui, sizeof(*ui));
    bcopy((char *)&pkt.data[pkt.off], (char *)ip, sizeof(*ip));
#else
    ui = (struct udpiphdr *)&pkt.data[pkt.off];
    ip = (struct ip *)&pkt.data[pkt.off];
#endif

    pkt.off += sizeof (struct udpiphdr);
    if (ui->ui_pr != IPPROTO_UDP) {
        return;
    }
 
    if (ip->ip_hl > (sizeof (struct ip) >> 2)) {
        return;
    }

    if (ntohs(ui->ui_dport) != KDP_REMOTE_PORT) {
      if (CORE_REMOTE_PORT == (ntohs(ui->ui_dport)) && 
          flag_panic_dump_in_progress) {
          last_panic_port = ui->ui_sport;
        }
      else
        return;
    }
    /* If we receive a kernel debugging packet whilst a 
     * core dump is in progress, abort the transfer and 
     * enter the debugger.
     */
    else
      if (flag_panic_dump_in_progress)
        {
          abort_panic_transfer();
          return;
        }

    if (!kdp.is_conn && !flag_panic_dump_in_progress) {
        enaddr_copy(eh->ether_dhost, &adr.loc.ea);
        adr.loc.in = ui->ui_dst;

        enaddr_copy(eh->ether_shost, &adr.rmt.ea);
        adr.rmt.in = ui->ui_src;
    }

    /*
     * Calculate kdp packet length.
     */
    pkt.len = ntohs((u_short)ui->ui_ulen) - sizeof (struct udphdr);
    pkt.input = TRUE;
}

static void
kdp_handler(
    void        *saved_state
)
{
    unsigned short              reply_port;
    kdp_hdr_t                   aligned_hdr, *hdr = &aligned_hdr;


    kdp.saved_state = saved_state;  // see comment in kdp_raise_exception

    do {
        while (!pkt.input)
            kdp_poll();
                        
#if DO_ALIGN
        bcopy((char *)&pkt.data[pkt.off], (char *)hdr, sizeof(*hdr));
#else
        hdr = (kdp_hdr_t *)&pkt.data[pkt.off];
#endif

        // ignore replies -- we're not expecting them anyway.
        if (hdr->is_reply) {
            goto again;
        }
        
        if (hdr->request == KDP_REATTACH)
          exception_seq = hdr->seq;

        // check for retransmitted request
        if (hdr->seq == (exception_seq - 1)) {
            /* retransmit last reply */
            (*kdp_en_send_pkt)(&saved_reply.data[saved_reply.off],
                            saved_reply.len);
            goto again;
        } else if (hdr->seq != exception_seq) {
            printf("kdp: bad sequence %d (want %d)\n",
                        hdr->seq, exception_seq);
            goto again;
        }
        
        if (kdp_packet((unsigned char*)&pkt.data[pkt.off], 
                        (int *)&pkt.len, 
                        (unsigned short *)&reply_port)) {
            kdp_reply(reply_port);
        }

again:
        pkt.input = FALSE;
    } while (kdp.is_halted);
}

static void
kdp_connection_wait(void)
{
        unsigned short          reply_port;
        boolean_t               kdp_call_kdb();
        struct ether_addr       kdp_mac_addr = kdp_get_mac_addr();
        unsigned int            ip_addr = ntohl(kdp_get_ip_address());

        printf( "ethernet MAC address: %02x:%02x:%02x:%02x:%02x:%02x\n",
            kdp_mac_addr.ether_addr_octet[0] & 0xff,
            kdp_mac_addr.ether_addr_octet[1] & 0xff,
            kdp_mac_addr.ether_addr_octet[2] & 0xff,
            kdp_mac_addr.ether_addr_octet[3] & 0xff,
            kdp_mac_addr.ether_addr_octet[4] & 0xff,
            kdp_mac_addr.ether_addr_octet[5] & 0xff);
                
        printf( "ip address: %d.%d.%d.%d\n",
            (ip_addr & 0xff000000) >> 24,
            (ip_addr & 0xff0000) >> 16,
            (ip_addr & 0xff00) >> 8,
            (ip_addr & 0xff));
            
        printf("\nWaiting for remote debugger connection.\n");

        if (reattach_wait == 0) {
                if((kdp_flag & KDP_GETC_ENA) && (0 != kdp_getc()))
                {
                        printf("Options.....    Type\n");
                        printf("------------    ----\n");
                        printf("continue....    'c'\n");
                        printf("reboot......    'r'\n");
#if MACH_KDB
                        printf("enter kdb...    'k'\n");
#endif
                }
        } else
                reattach_wait = 0;
    
        exception_seq = 0;

        do {
                kdp_hdr_t aligned_hdr, *hdr = &aligned_hdr;
        
                while (!pkt.input) {
                        if (kdp_flag & KDP_GETC_ENA) {
                                switch(kdp_getc()) {
                                case 'c':
                                        printf("Continuing...\n");
                                        return;
                                case 'r':
                                        printf("Rebooting...\n");
                                        kdp_reboot();
                                        break;
#if MACH_KDB
                                case 'k':
                                        printf("calling kdb...\n");
                                        if (kdp_call_kdb())
                                                return;
                                        else
                                                printf("not implemented...\n");
#endif
                                        default:
                                        break;
                                }
                        }
                        kdp_poll();
                }

#if DO_ALIGN
                bcopy((char *)&pkt.data[pkt.off], (char *)hdr, sizeof(*hdr));
#else
                hdr = (kdp_hdr_t *)&pkt.data[pkt.off];
#endif
                if (hdr->request == KDP_HOSTREBOOT) {
                        kdp_reboot();
                        /* should not return! */
                }
                if (((hdr->request == KDP_CONNECT) || (hdr->request == KDP_REATTACH)) &&
                        !hdr->is_reply && (hdr->seq == exception_seq)) {
                    if (kdp_packet((unsigned char *)&pkt.data[pkt.off], 
                                (int *)&pkt.len, 
                                (unsigned short *)&reply_port))
                                kdp_reply(reply_port);
                    if (hdr->request == KDP_REATTACH) {
                                reattach_wait = 0;
                                hdr->request=KDP_DISCONNECT;
                                exception_seq = 0;
                        }
                }

                pkt.input = FALSE;
        } while (!kdp.is_conn);
    
        if (current_debugger == KDP_CUR_DB)
                active_debugger=1;
        printf("Connected to remote debugger.\n");
}

static void
kdp_send_exception(
    unsigned int                exception,
    unsigned int                code,
    unsigned int                subcode
)
{
    unsigned short              remote_port;
    unsigned int                timeout_count = 100;
    unsigned int                poll_timeout;

    do {
        pkt.off = sizeof (struct ether_header) + sizeof (struct udpiphdr);
        kdp_exception((unsigned char *)&pkt.data[pkt.off], 
                        (int *)&pkt.len, 
                        (unsigned short *)&remote_port,
                        (unsigned int)exception, 
                        (unsigned int)code, 
                        (unsigned int)subcode);

        kdp_send(remote_port);
    
        poll_timeout = 50;
        while(!pkt.input && poll_timeout)
          {
            kdp_poll();
            poll_timeout--;
          }

        if (pkt.input) {
            if (!kdp_exception_ack(&pkt.data[pkt.off], pkt.len)) {
                pkt.input = FALSE;
            }
        }

        pkt.input = FALSE;

        if (kdp.exception_ack_needed)
            kdp_us_spin(250000);

    } while (kdp.exception_ack_needed && timeout_count--);
    
    if (kdp.exception_ack_needed) {
        // give up & disconnect
        printf("kdp: exception ack timeout\n");
        if (current_debugger == KDP_CUR_DB)
        active_debugger=0;
        kdp_reset();
    }
}

void
kdp_raise_exception(
    unsigned int                exception,
    unsigned int                code,
    unsigned int                subcode,
    void                        *saved_state
)
{
    int                 index;

    extern unsigned int disableDebugOuput;
    extern unsigned int disableConsoleOutput;

    disable_preemption();

    if (saved_state == 0) 
        printf("kdp_raise_exception with NULL state\n");

    index = exception;
    if (exception != EXC_BREAKPOINT) {
        if (exception > EXC_BREAKPOINT || exception < EXC_BAD_ACCESS) {
            index = 0;
        }
        printf("%s exception (%x,%x,%x)\n",
                exception_message[index],
                exception, code, subcode);
    }

    kdp_sync_cache();

    /* XXX WMG it seems that sometimes it doesn't work to let kdp_handler
     * do this. I think the client and the host can get out of sync.
     */
    kdp.saved_state = saved_state;
     
    if (pkt.input)
        kdp_panic("kdp_raise_exception");

    if (((kdp_flag & KDP_PANIC_DUMP_ENABLED) || (kdp_flag & PANIC_LOG_DUMP))
        && (panicstr != (char *) 0)) {

        kdp_panic_dump();

      }
    else
      if ((kdp_flag & PANIC_CORE_ON_NMI) && (panicstr == (char *) 0) &&
          !kdp.is_conn) {

        disableDebugOuput = disableConsoleOutput = FALSE;
        kdp_panic_dump();

        if (!(kdp_flag & DBG_POST_CORE))
          goto exit_raise_exception;
      }

 again:
    if (!kdp.is_conn)
        kdp_connection_wait();
    else {
        kdp_send_exception(exception, code, subcode);
        if (kdp.exception_ack_needed) {
            kdp.exception_ack_needed = FALSE;
            kdp_remove_all_breakpoints();
            printf("Remote debugger disconnected.\n");
          }
      }

    if (kdp.is_conn) {
        kdp.is_halted = TRUE;           /* XXX */
        kdp_handler(saved_state);
        if (!kdp.is_conn)
          {
            kdp_remove_all_breakpoints();
            printf("Remote debugger disconnected.\n");
          }
    }
    /* Allow triggering a panic core dump when connected to the machine
     * Continuing after setting kdp_trigger_core_dump should do the
     * trick.
     */
    if (1 == kdp_trigger_core_dump) {
        kdp_flag &= ~PANIC_LOG_DUMP;
        kdp_flag |= KDP_PANIC_DUMP_ENABLED;
        kdp_panic_dump();
      }

    kdp_sync_cache();

    if (reattach_wait == 1)
      goto again;
 exit_raise_exception:
    enable_preemption();
}

void
kdp_reset(void)
{
        kdp.reply_port = kdp.exception_port = 0;
        kdp.is_halted = kdp.is_conn = FALSE;
        kdp.exception_seq = kdp.conn_seq = 0;
}

struct corehdr *
create_panic_header(unsigned int request, const char *corename, 
                    unsigned length, unsigned int block)
{
  struct udpiphdr       aligned_ui, *ui = &aligned_ui;
  struct ip             aligned_ip, *ip = &aligned_ip;
  struct ether_header   *eh;
  struct corehdr        *coreh;
  const char            *mode = "octet";
  char                  modelen  = strlen(mode);

  pkt.off = sizeof (struct ether_header);
  pkt.len = length + ((request == KDP_WRQ) ? modelen : 0) + 
    (corename ? strlen(corename): 0) + sizeof(struct corehdr);

#if DO_ALIGN
  bcopy((char *)&pkt.data[pkt.off], (char *)ui, sizeof(*ui));
#else
  ui = (struct udpiphdr *)&pkt.data[pkt.off];
#endif
  ui->ui_next = ui->ui_prev = 0;
  ui->ui_x1 = 0;
  ui->ui_pr = IPPROTO_UDP;
  ui->ui_len = htons((u_short)pkt.len + sizeof (struct udphdr));
  ui->ui_src.s_addr = htonl(kdp_current_ip_address);
  ui->ui_dst.s_addr = panic_server_ip;
  ui->ui_sport = htons(CORE_REMOTE_PORT);
  ui->ui_dport = ((request == KDP_WRQ) ? htons(CORE_REMOTE_PORT) : last_panic_port);
  ui->ui_ulen = ui->ui_len;
  ui->ui_sum = 0;
#if DO_ALIGN
  bcopy((char *)ui, (char *)&pkt.data[pkt.off], sizeof(*ui));
  bcopy((char *)&pkt.data[pkt.off], (char *)ip, sizeof(*ip));
#else
  ip = (struct ip *)&pkt.data[pkt.off];
#endif
  ip->ip_len = htons(sizeof (struct udpiphdr) + pkt.len);
  ip->ip_v = IPVERSION;
  ip->ip_id = htons(ip_id++);
  ip->ip_hl = sizeof (struct ip) >> 2;
  ip->ip_ttl = udp_ttl;
  ip->ip_sum = 0;
  ip->ip_sum = htons(~ip_sum((unsigned char *)ip, ip->ip_hl));
#if DO_ALIGN
  bcopy((char *)ip, (char *)&pkt.data[pkt.off], sizeof(*ip));
#endif
    
  pkt.len += sizeof (struct udpiphdr);

  pkt.off += sizeof (struct udpiphdr);
  
  coreh = (struct corehdr *) &pkt.data[pkt.off];
  coreh->th_opcode = htons((u_short)request);
  
  if (request == KDP_WRQ)
    {
      register char *cp;

      cp = coreh->th_u.tu_rpl;
      strcpy (cp, corename);
      cp += strlen(corename);
      *cp++ = '\0';
      strcpy (cp, mode);
      cp+= modelen;
      *cp++ = '\0';
    }
  else
    {
      coreh->th_block = htonl((unsigned int) block);
    }

  pkt.off -= sizeof (struct udpiphdr);
  pkt.off -= sizeof (struct ether_header);

  eh = (struct ether_header *)&pkt.data[pkt.off];
  enaddr_copy(&kdp_current_mac_address, eh->ether_shost);
  enaddr_copy(&router_mac, eh->ether_dhost);
  eh->ether_type = htons(ETHERTYPE_IP);
    
  pkt.len += sizeof (struct ether_header);
  return coreh;
}

int kdp_send_panic_packets (unsigned int request, char *corename, 
                            unsigned int length, unsigned int txstart)
{
  unsigned int txend = txstart + length;
  int panic_error = 0;

  if (length <= SEGSIZE) {
    if ((panic_error = kdp_send_panic_pkt (request, corename, length, (caddr_t) txstart)) < 0) {
      printf ("kdp_send_panic_pkt failed with error %d\n", panic_error);
      return panic_error ;
    }
  }
  else
    {
      while (txstart <= (txend - SEGSIZE))  {
        if ((panic_error = kdp_send_panic_pkt (KDP_DATA, NULL, SEGSIZE, (caddr_t) txstart)) < 0) {
          printf ("kdp_send_panic_pkt failed with error %d\n", panic_error);
          return panic_error;
        }
        txstart += SEGSIZE;
        if (!(panic_block % 2000))
          printf(".");
      }
      if (txstart < txend) {
        kdp_send_panic_pkt(request, corename, (txend - txstart), (caddr_t) txstart);
      }
    }
}

int 
kdp_send_panic_pkt (unsigned int request, char *corename, 
                    unsigned int length, void *panic_data)
{
  struct corehdr *th = NULL;
  int poll_count = 2500;
  
  char rretries = 0, tretries = 0;
  /*
  extern signed long gIODebuggerSemaphore;
  */
  pkt.off = pkt.len = 0;
  
  if (request == KDP_WRQ) /* longer timeout for initial request */
    poll_count += 1000;

TRANSMIT_RETRY:
  tretries++;

  if (tretries > 2)
    printf("TX retry #%d ", tretries );
  
  if (tretries >=15) {
    /* This iokit layer issue can potentially 
     *cause a hang, uncomment to check if it's happening.
     */
    /*
      if (gIODebuggerSemaphore)
      printf("The gIODebuggerSemaphore is raised, preventing packet transmission (2760413)\n");
    */
    
    printf ("Cannot contact panic server, timing out.\n");
    return (-3);
  }

  th = create_panic_header(request, corename, length, panic_block);

  if (request == KDP_DATA || request == KDP_SEEK) {
      if (!kdp_vm_read ((caddr_t) panic_data, (caddr_t) th->th_data, length)) {
        memset ((caddr_t) th->th_data, 'X', length);
      }
    }

  (*kdp_en_send_pkt)(&pkt.data[pkt.off], pkt.len);

  /* Now we have to listen for the ACK */
 RECEIVE_RETRY:

  while (!pkt.input && flag_panic_dump_in_progress && poll_count) {
      kdp_poll();
      poll_count--;
    }

  if (pkt.input) {
    
    pkt.input = FALSE;
    
    th = (struct corehdr *) &pkt.data[pkt.off];
    /* These will eventually have to be ntoh[ls]'ed as appropriate */
    
    if (th->th_opcode == KDP_ACK && th->th_block == panic_block) {
    }
    else
      if (th->th_opcode == KDP_ERROR) {
        printf("Panic server returned error %d, retrying\n", th->th_code);
        poll_count = 1000;
        goto TRANSMIT_RETRY;
      }
      else 
        if (th->th_block == (panic_block -1)) {
          printf("RX retry ");
          if (++rretries > 1)
            goto TRANSMIT_RETRY;
          else
            goto RECEIVE_RETRY;
        }
  }
  else
    if (!flag_panic_dump_in_progress) /* we received a debugging packet, bail*/
      {
        printf("Received a debugger packet,transferring control to debugger\n");
        /* Configure that if not set ..*/
        kdp_flag |= DBG_POST_CORE;
        return (-2);
      }
    else /* We timed out */
      if (0 == poll_count) {
        poll_count = 1000;
        kdp_us_spin ((tretries%4) * panic_timeout); /* capped linear backoff */
        goto TRANSMIT_RETRY;
      }
  
  panic_block++;
  
  if (request == KDP_EOF)
    printf ("\nTotal number of packets transmitted: %d\n", panic_block);
  
  return 1;
}

/* Since we don't seem to have an isdigit() .. */
static int 
isdigit (char c)
{
  return ((c > 47) && (c < 58));
}
/* From user mode Libc - this ought to be in a library */
static char *
strnstr(s, find, slen)
        const char *s;
        const char *find;
        size_t slen;
{
  char c, sc;
  size_t len;
  
  if ((c = *find++) != '\0') {
    len = strlen(find);
    do {
      do {
        if ((sc = *s++) == '\0' || slen-- < 1)
          return (NULL);
      } while (sc != c);
      if (len > slen)
        return (NULL);
    } while (strncmp(s, find, len) != 0);
    s--;
  }
  return ((char *)s);
}

/* Horrid hack to extract xnu version if possible - a much cleaner approach
 * would be to have the integrator run a script which would copy the
 * xnu version into a string or an int somewhere at project submission
 * time - makes assumptions about sizeof(version), but will not fail if
 * it changes, but may be incorrect.
 */
 
static int 
kdp_get_xnu_version(char *versionbuf)
{
  extern const char version[];
  char *versionpos;
  char vstr[10];
  int retval = -1;

  strcpy(vstr, "custom");
   if (version) { 
       if (kdp_vm_read(version, versionbuf, 90)) {

           versionbuf[89] = '\0'; 
           
           versionpos = strnstr(versionbuf, "xnu-", 80);

           if (versionpos) {
             strncpy (vstr, versionpos, (isdigit (versionpos[7]) ? 8 : 7));
             vstr[(isdigit (versionpos[7]) ? 8 : 7)] = '\0';
             retval = 0;
           }
       }
   }
   strcpy(versionbuf, vstr);
   return retval;
}
/* Primary dispatch routine for the system dump */
void 
kdp_panic_dump()
{
  char corename[50];
  char coreprefix[10];
  int panic_error;
  extern char *debug_buf;
  extern vm_map_t kernel_map;

  extern char *inet_aton(const char *cp, struct in_addr *pin);

  extern char *debug_buf;
  extern char *debug_buf_ptr;
  uint64_t abstime;

  printf ("Entering system dump routine\n");
  
  if (!panicd_specified) {
      printf ("A panic server was not specified in the boot-args, terminating kernel core dump.\n");
      goto panic_dump_exit;
    }

  flag_panic_dump_in_progress = 1;
  not_in_kdp = 0;

  if (pkt.input)
    kdp_panic("kdp_panic_dump");

  kdp_get_xnu_version((char *) &pkt.data[0]);

  /* Panic log bit takes precedence over core dump bit */
  if ((panicstr != (char *) 0) && (kdp_flag & PANIC_LOG_DUMP))
    strncpy(coreprefix, "paniclog", sizeof(coreprefix));
  else
    strncpy(coreprefix, "core", sizeof(coreprefix));
  
  abstime = mach_absolute_time();
  pkt.data[10] = '\0';
  snprintf (corename, sizeof(corename), "%s-%s-%d.%d.%d.%d-%x", 
            coreprefix, &pkt.data[0],
           (kdp_current_ip_address & 0xff000000) >> 24,
           (kdp_current_ip_address & 0xff0000) >> 16,
           (kdp_current_ip_address & 0xff00) >> 8,
           (kdp_current_ip_address & 0xff),
           (unsigned int) (abstime & 0xffffffff));

  if (0 == inet_aton(panicd_ip_str, (struct in_addr *) &panic_server_ip)) {
      printf("inet_aton() failed interpreting %s as a panic server IP\n", 
             panicd_ip_str);
    }
  else
    printf("Attempting connection to panic server configured at IP %s\n", 
           panicd_ip_str);

  if (router_specified) {
      if (0 == inet_aton(router_ip_str, (struct in_addr *) &parsed_router_ip)){
          printf("inet_aton() failed interpreting %s as an IP\n", router_ip);
        }
      else {
          router_ip = parsed_router_ip;
          printf("Routing through specified router IP %s (%d)\n", router_ip_str, router_ip);
          /* We will eventually need to resolve the router's MAC ourselves,
           * if one is specified,rather than being set through the BSD callback
           * but the _router_ip option does not function currently
           */
        }
    }
  /* These & 0xffs aren't necessary,but cut&paste is ever so convenient */
  printf("Routing via router MAC address: %02x:%02x:%02x:%02x:%02x:%02x\n",
          router_mac.ether_addr_octet[0] & 0xff,
          router_mac.ether_addr_octet[1] & 0xff,
          router_mac.ether_addr_octet[2] & 0xff,
          router_mac.ether_addr_octet[3] & 0xff,
          router_mac.ether_addr_octet[4] & 0xff,
          router_mac.ether_addr_octet[5] & 0xff);

  printf("Kernel map size is %d\n", get_vmmap_size(kernel_map));
  printf ("Sending write request for %s\n", corename);  

  if ((panic_error = kdp_send_panic_pkt (KDP_WRQ, corename, 0 , NULL) < 0)) {
      printf ("kdp_send_panic_pkt failed with error %d\n", panic_error);
      goto panic_dump_exit;
    }

  /* Just the panic log requested */
  if ((panicstr != (char *) 0) && (kdp_flag & PANIC_LOG_DUMP)) {
    printf("Transmitting panic log, please wait: ");
    kdp_send_panic_packets (KDP_DATA, corename, (debug_buf_ptr - debug_buf), (unsigned int) debug_buf);
    kdp_send_panic_pkt (KDP_EOF, NULL, 0, ((void *) 0));
    printf("Please file a bug report on this panic, if possible.\n");
    goto panic_dump_exit;
    }
  
  /* We want a core dump if we're here */
  kern_dump();
panic_dump_exit:
  not_in_kdp = 1;
  flag_panic_dump_in_progress = 0;
  panic_block = 0;
  pkt.input = FALSE;
  pkt.len = 0;
  kdp_reset();
  return;
}

void 
abort_panic_transfer()
{
  flag_panic_dump_in_progress = 0;
  not_in_kdp = 1;
  panic_block = 0;
}