100 lines
2.7 KiB
Plaintext
100 lines
2.7 KiB
Plaintext
*** sn_packets.c.orig Fri Apr 18 16:33:58 1997
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--- sn_packets.c Thu May 7 15:02:14 1998
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***************
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*** 43,48 ****
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--- 43,49 ----
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struct UDP_header UDPhead;
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int i;
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+ short int dummy; /* 2 bytes, important */
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memcpy(&IPhead,(sp+PROTO_HEAD),sizeof(struct IP_header));
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/* IP header Conversion */
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***************
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*** 51,56 ****
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--- 52,58 ----
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unwrapped->TCP_len = 0; /* Reset structure NEEDED!!! */
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unwrapped->UDP_len = 0;
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unwrapped->DATA_len = 0;
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+ unwrapped->FRAG_nf = 0;
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if(NO_CHKSUM == 0)
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{
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***************
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*** 75,106 ****
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--- 77,150 ----
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/* restore orig buffer */
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/* general programming rule */
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}
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+
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+ #ifdef DEBUG_ONSCREEN
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+ printf("IPheadlen: %d total length: %d\n", unwrapped->IP_len,
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+ ntohs(IPhead.length));
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+ #endif
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+
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+ dummy=ntohs(IPhead.flag_offset); dummy<<=3;
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+ if( dummy!=0 ) /* we have offset */
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+ {
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+ unwrapped->FRAG_nf = 1;
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+ }
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+
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if(IPhead.protocol == TCP ) /* TCP */
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{
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+ if(unwrapped->FRAG_nf == 0)
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+ {
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+ if( (ntohs(IPhead.length)-(unwrapped->IP_len))<20 )
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+ return CORRUPT_IP;
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+
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memcpy(&TCPhead,(sp+PROTO_HEAD+(unwrapped->IP_len)),
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sizeof(struct TCP_header));
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unwrapped->TCP_len = ntohs(TCPhead.offset_flag) & 0xF000;
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unwrapped->TCP_len >>= 10;
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unwrapped->DATA_len = ntohs(IPhead.length) -
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(unwrapped->IP_len) - (unwrapped->TCP_len);
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+ }
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+ else
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+ {
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+ unwrapped->DATA_len = ntohs(IPhead.length)
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+ - (unwrapped->IP_len);
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+ }
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return TCP;
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}
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if(IPhead.protocol == ICMP ) /* ICMP */
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{
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+ if(unwrapped->FRAG_nf == 0)
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+ {
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+ if( (ntohs(IPhead.length)-(unwrapped->IP_len))<4 )
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+ return CORRUPT_IP;
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memcpy(&ICMPhead,(sp+PROTO_HEAD+(unwrapped->IP_len)),
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sizeof(struct ICMP_header));
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unwrapped->ICMP_len = ICMP_HEADLENGTH;
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unwrapped->DATA_len = ntohs(IPhead.length) -
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(unwrapped->IP_len) - (unwrapped->ICMP_len);
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return ICMP;
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+ }
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+ else
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+ {
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+ return -1; /* don't handle fragmented ICMP */
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+ }
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}
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if(IPhead.protocol == UDP ) /* UDP */
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{
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+ if(unwrapped->FRAG_nf == 0)
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+ {
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+ if( (ntohs(IPhead.length)-(unwrapped->IP_len))<8 )
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+ return CORRUPT_IP;
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memcpy(&UDPhead,(sp+PROTO_HEAD+(unwrapped->IP_len)),
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sizeof(struct UDP_header));
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unwrapped->UDP_len = UDP_HEADLENGTH;
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unwrapped->DATA_len = ntohs(IPhead.length) -
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(unwrapped->IP_len) - (unwrapped->UDP_len);
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+ }
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+ else
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+ {
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+ unwrapped->DATA_len = ntohs(IPhead.length)
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+ - (unwrapped->IP_len);
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+ }
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return UDP;
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}
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return -1;
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