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<td width="68%" background="DDl_back2.jpg" height="44"><big><big><font face="黑体"><p align="center"> ● UNIX网络编程 (BM: clown) </font></big></big></td></tr>
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<hr><p align="left"><small>---------------------------------------------------------------------------- <br>
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: taov 于 00-7-31 11:44:42 加贴在 绿盟科技论坛(bbs.nsfocus.com)--UNIX系统安全 <br>
： <br>
哪位详细说说libcpap中pcap_loop的用法? <br>
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: 小四 于 00-7-31 12:25:54 加贴在 绿盟科技论坛(bbs.nsfocus.com)--UNIX系统安全 <br>
： <br>
估计没什么人乐意回答这个问题。因为tcpdump的源代码满世界在飞。 <br>
上次你问了个getopt的问题，我贴了个针对性的简单却完整的源代码，你 <br>
说看不明白，那么这次你问pcap_loop，别人能如何回答你呢？叫他/她给 <br>
你贴一段代码么？那和看tcpdump.tar.gz有什么区别？下面是以BPF为例 <br>
的pcap循环。如果永远不想自己花点时间看那些sample，而指望BBS上别 <br>
人能告诉你什么的话，对自己不负责任，对别人也不。 <br>
int pcap_read ( void ) <br>
{ <br>
int readCount; <br>
int count = 0; <br>
register u_char * begin; <br>
register u_char * end; <br>
pcap_read_0: <br>
readCount = remainCount; <br>
if ( remainCount == 0 ) /* 已经处理完上次残留数据 */ <br>
{ <br>
readCount = read( if_eth_fd, packetBuffer, packetBufferSize ); <br>
if ( readCount < 0 ) <br>
{ <br>
/* Don't choke when we get ptraced */ <br>
switch ( errno ) <br>
{ <br>
case EINTR: <br>
goto pcap_read_0; <br>
case EWOULDBLOCK: <br>
return( 0 ); <br>
} <br>
fprintf( outputFile, "pcap_read error: %s\n", strerror( errno ) <br>
); <br>
return( FAILURE ); <br>
} <br>
begin = packetBuffer; <br>
} <br>
else <br>
{ <br>
begin = beginPointer; <br>
} <br>
/* Loop through each packet. */ <br>
#define bhp ( ( struct bpf_hdr * )begin ) <br>
end = begin + readCount; <br>
while ( begin < end ) <br>
{ <br>
register int caplen, hdrlen; <br>
caplen = bhp->bh_caplen; <br>
hdrlen = bhp->bh_hdrlen; <br>
/* A bpf_hdr matches a pcap_pkthdr. */ <br>
doTcpData( ( u_char * )( begin + hdrlen ) ); <br>
begin += BPF_WORDALIGN( caplen + hdrlen ); /* 必须理解这里 */ <br>
count++; <br>
if ( count >= captureCount ) <br>
{ <br>
beginPointer = begin; <br>
remainCount = end - begin; <br>
return( count ); <br>
} <br>
} <br>
#undef bhp <br>
remainCount = 0; /* 最后一个包可能不完整，只好丢弃 */ <br>
return( count ); <br>
} /* end of pcap_read */ <br>
int readDevice ( void ) <br>
{ <br>
register int count; <br>
while ( 1 ) <br>
{ <br>
count = 0; <br>
/* <br>
* keep reading until we get something <br>
* or an error occurs <br>
*/ <br>
do <br>
{ <br>
count = pcap_read(); <br>
} while ( count == 0 ); <br>
if ( count < 0 ) <br>
{ <br>
return( count ); <br>
} <br>
// if ( captureCount > 0 ) <br>
// { <br>
// captureCount -= count; /* 继续读够指定包数 */ <br>
// if ( captureCount <= 0 ) <br>
// { <br>
// return( SUCCESS ); <br>
// } <br>
// } <br>
} /* end of while */ <br>
return( SUCCESS ); <br>
} /* end of readDevice */ <br>
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