?? icmphdr.c
字號:
/* ICMP header conversion routines
*/
#include "global.h"
#include "mbuf.h"
#include "internet.h"
#include "ip.h"
#include "icmp.h"
/* Generate ICMP header in network byte order, link data, compute checksum */
void
htonicmp(
struct icmp *icmp,
struct mbuf **bpp
){
register uint8 *cp;
uint16 checksum;
pushdown(bpp,NULL,ICMPLEN);
cp = (*bpp)->data;
*cp++ = icmp->type;
*cp++ = icmp->code;
cp = put16(cp,0); /* Clear checksum */
switch(icmp->type){
case ICMP_DEST_UNREACH:
if(icmp->code == ICMP_FRAG_NEEDED){
/* Deering/Mogul max MTU indication */
cp = put16(cp,0);
cp = put16(cp,icmp->args.mtu);
} else
cp = put32(cp,0L);
break;
case ICMP_PARAM_PROB:
*cp++ = icmp->args.pointer;
*cp++ = 0;
cp = put16(cp,0);
break;
case ICMP_REDIRECT:
cp = put32(cp,icmp->args.address);
break;
case ICMP_ECHO:
case ICMP_ECHO_REPLY:
case ICMP_TIMESTAMP:
case ICMP_TIME_REPLY:
case ICMP_INFO_RQST:
case ICMP_INFO_REPLY:
cp = put16(cp,icmp->args.echo.id);
cp = put16(cp,icmp->args.echo.seq);
break;
default:
cp = put32(cp,0L);
break;
}
/* Compute checksum, and stash result */
checksum = cksum(NULL,*bpp,len_p(*bpp));
cp = &(*bpp)->data[2];
cp = put16(cp,checksum);
}
/* Pull off ICMP header */
int
ntohicmp(icmp,bpp)
struct icmp *icmp;
struct mbuf **bpp;
{
uint8 icmpbuf[8];
if(icmp == (struct icmp *)NULL)
return -1;
if(pullup(bpp,icmpbuf,8) != 8)
return -1;
icmp->type = icmpbuf[0];
icmp->code = icmpbuf[1];
switch(icmp->type){
case ICMP_DEST_UNREACH:
/* Retrieve Deering/Mogul MTU value */
if(icmp->code == ICMP_FRAG_NEEDED)
icmp->args.mtu = get16(&icmpbuf[6]);
break;
case ICMP_PARAM_PROB:
icmp->args.pointer = icmpbuf[4];
break;
case ICMP_REDIRECT:
icmp->args.address = get32(&icmpbuf[4]);
break;
case ICMP_ECHO:
case ICMP_ECHO_REPLY:
case ICMP_TIMESTAMP:
case ICMP_TIME_REPLY:
case ICMP_INFO_RQST:
case ICMP_INFO_REPLY:
icmp->args.echo.id = get16(&icmpbuf[4]);
icmp->args.echo.seq = get16(&icmpbuf[6]);
break;
}
return 0;
}
?? 快捷鍵說明
復制代碼
Ctrl + C
搜索代碼
Ctrl + F
全屏模式
F11
切換主題
Ctrl + Shift + D
顯示快捷鍵
?
增大字號
Ctrl + =
減小字號
Ctrl + -