Shulou(Shulou.com)06/01 Report--

/ / i386 is little_endian.

# ifndef LITTLE_ENDIAN

# define LITTLE_ENDIAN (1) / / BYTE ORDER

# else

# error Redefine LITTLE_ORDER

# endif

/ / Mac header with a total length of 14 bytes

Typedef struct _ eth_hdr

{

Unsigned char dstmac [6]; / / destination mac address

Unsigned char srcmac [6]; / / Source mac address

Unsigned short eth_type; / / Ethernet type

} eth_hdr

/ / IP header with a total length of 20 bytes

Typedef struct _ ip_hdr

{

# if LITTLE_ENDIAN

Unsigned char ihl:4; / / header length

Unsigned char version:4, / / version

# else

Unsigned char version:4, / / version

Unsigned char ihl:4; / / header length

# endif

Unsigned char tos; / / Service type

Unsigned short tot_len; / / Total length

Unsigned short id; / / Flag

Unsigned short frag_off; / / fragment offset

Unsigned char ttl; / / time to live

Unsigned char protocol; / / protocol

Unsigned short chk_sum; / / Inspection and

Struct in_addr srcaddr; / / Source IP address

Struct in_addr dstaddr; / / destination IP address

} ip_hdr

/ / TCP header with a total length of 20 bytes

Typedef struct _ tcp_hdr

{

Unsigned short src_port; / / Source port number

Unsigned short dst_port; / / destination port number

Unsigned int seq_no; / / Serial number

Unsigned int ack_no; / / confirmation number

# if LITTLE_ENDIAN

Unsigned char reserved_1:4; / / preserves 4 of the 6-bit header length

Unsigned char thl:4; / / tcp header length

Unsigned char flag:6; / / 6-bit flag

Unsigned char reseverd_2:2; / / keep 2 of the 6 bits

# else

Unsigned char thl:4; / / tcp header length

Unsigned char reserved_1:4; / / preserves 4 of the 6-bit header length

Unsigned char reseverd_2:2; / / keep 2 of the 6 bits

Unsigned char flag:6; / / 6-bit flag

# endif

Unsigned short wnd_size; / / 16-bit window size

Unsigned short chk_sum; / / 16-bit TCP test and

Unsigned short urgt_p; / / 16 is an emergency pointer

} tcp_hdr

/ / UDP header with a total length of 8 bytes

Typedef struct _ udp_hdr

{

Unsigned short src_port; / / remote port number

Unsigned short dst_port; / / destination port number

Unsigned short uhl; / / udp header length

Unsigned short chk_sum; / / 16-bit udp test and

} udp_hdr

/ / ICMP header with a total length of 4 bytes

Typedef struct _ icmp_hdr

{

Unsigned char icmp_type; / / type

Unsigned char code; / / Code

Unsigned short chk_sum; / / 16-bit test sum

} icmp_hdr

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