icmp.c

嵌入式RMON,RMON为Remote monitor的缩写,基于SNMP为网络提供主动监控及错误告警,智能交换路由必备协议

/* Beholder RMON ethernet network monitor,Copyright (C) 1993 DNPAP group */
/* See file COPYING 'GNU General Public Licence' for copyright details   */
#include <stdio.h>
#include <ip.h>
#include <nw.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <netinet/in.h>
#include <dinet.h>
#include <chain.h>
#include "icmp.h"


typedef struct _HDR  HDR;

struct _HDR
{
    BYTE        type;
    BYTE        code;
    WORD        check;
};



static void         Rcve(NW_DG *dg, char *addr, BYTE *frame, int length, void *parm);
static CHAIN        *HdrDecode(CHAIN *chain, ICMP_HDR *icmpHdr);
static CHAIN        *HdrEncode(CHAIN *chain, ICMP_HDR *icmpHdr);
static ICMP_DESCR   *DescrFind(ICMP_HDR *icmpHdr, IP_HDR *ipHdr);
static WORD         Wildcards(ICMP_DESCR *icmp);



ICMP_DESCR *icmpDescrList = 0;

NW_DG *icmpNw=0;

BOOLEAN IcmpInit(void)
{
    static BOOLEAN init=FALSE;
    
    if (!init) 
    {
        icmpNw=NwDgAccept("icmp", Rcve, 0);
        if (icmpNw==0)   
            return FALSE;   
        init=TRUE;
    }
     
    return TRUE;
}


BOOLEAN IcmpRegister(ICMP_DESCR *icmp)
{
    ICMP_DESCR **p;

    for (p=&icmpDescrList; *p!=0; p=&(*p)->next)
    {
        if (Wildcards(*p) > Wildcards(icmp))
            break;
    }
    icmp->next = *p;
    *p = icmp;

    return TRUE;
}


BOOLEAN IcmpRemove(ICMP_DESCR *icmp)
{
    ICMP_DESCR **p;

    for (p=&icmpDescrList; *p!=0; p=&(*p)->next)
    {
        if (*p == icmp)
            *p = icmp->next;
        return TRUE;
    }

    return FALSE;
}

BOOLEAN IcmpSend(CHAIN *chain, ICMP_HDR *icmpHdr, IP_HDR *ipHdr)
{
    CHAIN       *new;
    BYTE        addr[32];
    int         length;
    BYTE        *frame;
    BOOLEAN     success = FALSE;
    
    new = HdrEncode(chain, icmpHdr);
    if (new != 0)
    {
        length = ChainLength(chain);
        frame = DnpapMalloc(length);  
        if (frame!=0)
        {
            if (ChainCopy(chain, frame, length))
            {
                sprintf(addr,"icmp:%s",Inet_NtoA(ipHdr->dst)); 
            
                if (NwDgSendTo(0, addr, frame, length))
                    success = FALSE;
            }
            DnpapFree(frame);
        } 
    }
    
    return success;
}





static CHAIN *HdrDecode(CHAIN *chain, ICMP_HDR *icmpHdr)
{
    HDR *h;
    

    if (IpHdrCheck(chain, ChainLength(chain)) != 0)
        return 0;
    
    h = (HDR *)ChainPop(&chain, sizeof(HDR));
    if (h==0)
        return 0;
    
    icmpHdr->type  = h->type;
    icmpHdr->code  = h->code;
    icmpHdr->check = IpN2HWord(h->check);

    return chain;
}


static CHAIN *HdrEncode(CHAIN *chain, ICMP_HDR *icmpHdr)
{
    HDR *h;
    
    h = (HDR *)ChainPush(&chain, sizeof(HDR));
    if (h==0)
        return 0;

    h->type     = icmpHdr->type;  
    h->code     = icmpHdr->code;  
    h->check    = 0;

    h->check    = IpHdrCheck(chain, ChainLength(chain));
    
    return chain;
}




static ICMP_DESCR *DescrFind(ICMP_HDR *icmpHdr, IP_HDR *ipHdr)
{
    ICMP_DESCR *p;


    for (p=icmpDescrList; p!=0; p=p->next)
    {
        if (
                (p->locAddr==ICMP_ADDR_ANY || p->locAddr==ipHdr->dst)    &&
                (p->remAddr==ICMP_ADDR_ANY || p->remAddr==ipHdr->src)    &&
                (p->type==ICMP_TYPE_ANY || p->type==icmpHdr->type)    &&
                (p->code==ICMP_CODE_ANY || p->type==icmpHdr->code) 
           ) 
        {
            return p;
        }
    }
   
    return 0;
}

                                 
static WORD Wildcards(ICMP_DESCR *icmp)
{
    WORD n=0;

    if (icmp->locAddr == ICMP_ADDR_ANY)
        n++;
    if (icmp->remAddr == ICMP_ADDR_ANY)
        n++;
    if (icmp->type == ICMP_TYPE_ANY)
        n++;
    if (icmp->code == ICMP_CODE_ANY)
        n++;

    return n;
}



static void Rcve(NW_DG *dg, char *addr, BYTE *frame, int length, void *parm)
{
    CHAIN       *new, *chain;
    ICMP_HDR    icmpHdr;
    IP_HDR      ipHdr;
    ICMP_DESCR  *descr;
    BOOLEAN     success = FALSE;
                            
    
    if (Addr2Host(addr, &(ipHdr.src))  
    {
        chain=ChainAlloc(0, frame, length, length, 0, 0); 
        if (chain!=0)
        { 
            new = HdrDecode(chain, &icmpHdr);
            if (new != 0)
            {     
                descr = DescrFind(&icmpHdr, &ipHdr);
                if(descr)
                {
                    if(descr->Rcve(descr, chain, &icmpHdr, &ipHdr))
                    {
                        success = TRUE;
                    }
                }
                if (new != chain)
                    ChainFree(new); 
            }   
            ChainFree(chain);
        } 
    }
}