The tragedy of Htons and htonl

Do not say anything, first throw the question :

Client: Connect:connection refused

The following issues occur with the debug server:

Port: Incoming server port number, set to 8888

Srvaddr.sin_port: The local port number is converted to a network port number and stored in the network socket interface address data structure

This is 0!

HTONL is used here.

This is the client who died in htons, dividing the client and server at both ends of the galaxy.

cause : The data type of sin_port in the network socket address data structure is not noticed, and the htonl can be arbitrarily substituted for htons use.

IPV4 Universal Network Socket Interface address data structure:

struct sockaddr_in {                sa_family_t    sin_family; /* address family: af_inet  */               in_port_t       sin_port;   /* port in network byte  order */                struct in_addr sin_addr;   /* internet address */            };       /* internet  address. */           struct in_addr  {               uint32_t        s_addr;     /* address in network byte order */            };

Where:in_port_t : TCP or UDP port, typically uint16_t

Ps: data type in POSIX.LG

Data type	Description	Header file
int8_t	Signed 8-bit integer	Sys/types.h
uint8_t	Unsigned 8-bit integer	Sys/types.h
int16_t	Signed 16-bit integer	Sys/types.h
uint16_t	Unsigned 16-bit integer	Sys/types.h
int32_t	Signed 32-bit integer	Sys/types.h
uint32_t	Unsigned 32-bit integer	Sys/types.h
sa_family_t	Address clusters for the address structure of the socket interface	Sys/socket.h
Socklen_t	The length of the set interface address, typically uint32_t	Sys/socket.h
in_port_t	TCP or UDP port, typically uint16_t	Netinet/in.h
in_addr_t	Ipv4 address, typically uint32_t	Netinet/in.h

byte sort function

There are two kinds of data storage in computer memory, one is small- endian, that is, low-address storage data low-byte, high-address storage data high-byte, one is the big- endian byte-order , that is, the low address stores the high byte, the high address stores the low byte. The byte order of the network is big endian, and the host byte order may be the small-endian byte order, so there is the problem of byte-order conversion.

Function:

uint16_t htons (uint16_t hostvalue); uint32_t htonl (uint32_t hostvalue); uint16_t ntohs (uint16_t netvalue); uint16_t Ntohl (uint32_t netvalue);

header file:netinet/in.h

Description: the H representation in the function means that the host,n means that the network,s represents short,l for long, using the htons conversion port number, htonl and Ntohl to convert the IP address.

Results at a glance .....

Ps: Part of the content quoted from: http://blog.csdn.net/xiaoweibeibei/article/details/6584250

The tragedy of Htons and htonl