IP header, TCP header, UDP header, Mac frame header definition

First, the Mac frame header definition

/* Data frame definition, first 14 bytes, tail 4 bytes */

typedef struct _MAC_FRAME_HEADER {

Char m_cdstmacaddress[6]; Destination MAC Address

Char m_csrcmacaddress[6]; SOURCE MAC Address

Short M_ctype; The previous layer protocol type, such as 0x0800 represents the previous layer is the IP protocol, 0x0806 is ARP

}__ATTRIBUTE__ ((packed)) Mac_frame_header,*pmac_frame_header;

typedef struct _MAC_FRAME_TAIL {

unsigned int m_schecksum; Data frame tail Check and

}__ATTRIBUTE__ ((Packed)) Mac_frame_tail, *pmac_frame_tail;

Second, the definition of IP header structure

/*ip header definition, total 20 bytes */

typedef struct _IP_HEADER {

Char M_cversionandheaderlen; Version information (first 4 bits), head length (last 4 bits)

Char M_ctypeofservice; Service Type 8-bit

Short M_stotallenofpacket; Packet length

Short M_spacketid; Packet identification

Short M_ssliceinfo; Shard usage

Char M_cttl; Survival time

Char M_ctypeofprotocol; Protocol type

Short m_schecksum; Checksum

unsigned int m_uisourip; Source IP

unsigned int m_uidestip; Destination IP

} __attribute__ ((packed)) Ip_header, *pip_header;

Third, TCP header structure definition

/*TCP header definition, total 20 bytes */

typedef struct _TCP_HEADER {

Short M_ssourport; Source Port number 16bit

Short M_sdestport; Destination port number 16bit

unsigned int m_uisequnum; Serial number 32bit

unsigned int m_uiacknowledgenum; Confirmation Number 32bit

Short M_sheaderlenandflag; Top 4 bits: TCP header length, medium 6 bit: reserved, last 6 bits: Flag bit

Short m_swindowsize; Window Size 16bit

Short m_schecksum; Inspection and 16bit

Short M_surgentpointer; Emergency data offset 16bit

}__ATTRIBUTE__ ((Packed)) Tcp_header, *ptcp_header;

Option definitions in the/*TCP header

Kind (8bit) +length (8bit, length of the entire option, including the first two parts) + content (if any)

KIND = 1 means no operation NOP, no back part

2 indicates the length of the maximum segment option after maximum segment (in bytes, 1+1+ content part length)

3 indicates that length after Windows scale is the size of the Windows Scale option (in bytes, 1+1+ content part length)

4 means SACK permitted length is 2, no content part

5 indicates that this is a sack packet length of 2, no content part

8 means timestamp, length 10, timestamp with 8 bytes */

typedef struct _TCP_OPTIONS {

Char M_ckind;

Char m_clength;

Char m_ccontext[32];

}__ATTRIBUTE__ ((Packed)) tcp_options, *ptcp_options;

Iv. definition of UDP header structure

/*UDP header definition, total 8 bytes */

typedef struct _UDP_HEADER {

unsigned short m_ussourport; Source Port number 16bit

unsigned short m_usdestport; Destination port number 16bit

unsigned short m_uslength; Packet length 16bit

unsigned short m_uschecksum; Checksum 16bit

}__ATTRIBUTE__ ((Packed)) Udp_header, *pudp_header;

IP header, TCP header, UDP header, Mac frame header definition