[Linux Network Programming learning notes] socket address Structure

I haven't read the Linux network programming book for a long time. Today I see the key part: TCP socket. Next let's take a look at the socket address Structure

Linux sockets support multiple protocols. Each protocol uses a different address structure. In the header file <Linux/socket. h>, there is an old-fashioned structure (this is not enough currently ).

 
StructSockaddr
 

{
 

Unsigned ShortSa_family;// The protocol cluster address type of the socket, and the TCP/IP protocol for IPv4 address type is af_inet
 

CharSa_data [14];// Store the specific Protocol address
 

 
};
 

The following sockaddr_in structure is generally used (used to set/obtain address information ):

 
StructSockaddr_in
 

 
{
 

 
Unsigned ShortSin_len; // IPv4 address Length
 

Short IntSin_family; // indicates the protocol cluster. In TCP socket programming, it can only be af_inet.
 

Unsigned ShortSin_port; // The storage port number (in the byte sequence of the network). The data type is a 16-character unsigned integer type.
 

StructIn_addr sin_addr; // storage IP address. The IP address is an in_add struct (the structure is shown below)
 

Unsigned CharSin_zero [8]; // reserved NULL bytes to keep sockaddr and sockaddr_in data structures of the same size
 

};
 

Here, the data structure of in_addr is as follows:

 
StructIn_addr
 

{
 

 
Unsigned LongS_addr; // store IP addresses in byte order.
 

 
};
 

In the currently popular IPv6, the socket address structure uses the following structure (the members in the structure are ordered ):

 
# Define sin6_len
 

 
StructSockaddr_in6
 

 
{
 

Unsigned Short IntSin6_len; // IPv6 structure length. It is an unsigned 8 Integer, indicating that 128 is the IPv6 address length.
 

Short IntSin6_family; // address type af_inet6
Unsigned Short Int sin6_port; // The storage port number, in bytes.
 

Unsigned Short IntSin6_flowinfo; // The 24-bit low is the traffic label, followed by the 4-bit priority mark, and the remaining four are retained.
 

StructIn6_addr sin6_addr; // IPv6 address, in bytes
 

 
};
 

 
StructIn6_addr
 

 
{
 

Unsigned LongS6_addr; // 128-bit IPv6 address, in bytes
 

 
};
 

Let's take an example to better illustrate the application of these struct structures. The following uses IPv4 as an example:

 
StructSockaddr_in mysock;
 

Mysock. sin_family = af_inet;// TCP address Structure
 

Mysock. sin_port = htons (3490 );// Byte sequence Conversion Function (I will introduce it later)
 

Mysock. sin_addr.s_addr = inet_addr ("166.111.160.10");// Set the IP address
 

Bzero (& (mysock. sin_zero), 8 );// Set sin_zero to 8-bit reserved bytes
 

// If mysock. sin_addr.s_addr = inaddr_any, no IP address is specified (used for serverProgram)
 

Some basic functions:

IP address conversion functions: inet_addr () and inet_ntoa ()

Format:

Unsigned LongInet_addr (Const Char* CP );
 

Char* Inet_ntoa (StructIn_addr in );