TCPIP Principles and Programming - 02计算机网络课件

Socket Networking APIs
• Unix/Linux Sockets • WinSock
– /enus/library/ms737523.aspx – /enus/library/ms741416.aspx
TCP|SCTP UDP SCTP IPv6
Yes Yes Yes Yes Yes
Figure 4.5 Combinations of family and type for the socket function
Extracted from Unix Network Programming, Vol. 1, 3rd. Ed., W. Stevens,
struct sockaddr { uint8_t sa_len; sa_family_t sa_family;/* address family: AF_xxx value */ char sa_data[14]; /* protocol-specific address */ }; /* defined in <sys/socket.h> header */
SOCK_STREAM
stream socket
SOCK_DGRAM datagram socket SOCK_SEQPACKET sequenced packet socket SOCK_RAW raw socket
Figure 4.3 type of socket for socket function
Socket Network Programming
Content
• • • • Socket Introduction TCP Stream Socket UDP Datagram Socket Example
Socket Introduction
7
6 5 4 3 2 1
application presentation session transport network datalink physical
Extracted from Unix Network Programming, Vol. 1, 3rd. Ed., W. Stevens,
Protocol IPPROTO_TCP IPPROTO_UDP IPPROTO_SCTP
Description TCP transport protocol UDP transport protocol SCTP transport protocol
bind Function
• The bind function assigns a local protocol address to a socket. With the Internet protocols, the protocol address is the combination of either a 32-bit IPv4 address or a 128-bit IPv6 address, along with a 16-bit TCP or UDP port number.
Conclusion
• Basic Concepts
– – – – – – Socket Socket address structure Byte ordering TCP stream socket UDP datagram socket Concurrent Servers
family
Description
UDP Datagram Socket
UDP Server socket() well-known port UDP Client socket() sendto()
bind() recvfrom()
blocks unitl datagram received from client
process request sendto()
read()
close()
write()
read()
close()
Figure 4.1 Socket functions for elementary TCP client/server
Extracted from Unix Network Programming, Vol. 1, 3rd. Ed., W. Stevens,
Byte Manipulation Functions
We need some types of functions when dealing with socket address structures because we need to manipulate fields such as IP addresses, which can contain bytes of 0, but are not C character strings.
Figure 4.4 protocol of sockets for AF_INET or AF_INET6 AF_INET SOCK_STREAM SOCK_DGRAM SOCK_SEQPACKET SOCK_RAW AF_INET6 AF_Local AF_Route AF_Key
TCP|SCTP UDP SCTP IPv4
TCP Server socket() well-known port bind() listen() accept() TCP Client socket() connect() write() blocks until connection from client connection establishment (TCP three-way handshake) read() process request
#include <strings.h> void bzero(void *dest, size_t nbytes); void bcopy(const void *src, void *dest, size_t nbytes); int bcmp(const void *ptr1, const void *ptr2, size_t nbytes); /* Returns: 0 if equal, nonzero if unequal */
IPv4 Socket Address Structures
struct in_addr { in_addr_t s_addr; /* 32-bit IPv4 address */ /* network byte ordered */ }; struct sockaddr_in { uint8_t sin_len; /* length of structure (16) */ sa_family_t sin_family; /* AF_INET */ in_port_t sin_port;/* 16-bit TCP or UDP port number */ /* network byte ordered */ struct in_addr sin_addr; /* 32-bit IPv4 address */ /* network byte ordered */ char sin_zero[8]; /* unused */ }; /* defined in <netinet/in.h> */
OSI model
application details
application
Sockets
user process
TCP
UDP
XTI kernel communications details
ቤተ መጻሕፍቲ ባይዱ
IPv4, IPv6 device driver and hardware
Internet protocol suite
AF_INET AF_INET6 AF_LOCAL AF_ROUTE
AF_KEY type
IPv4 protocols IPv6 protocols Unix domain protocols Routing sockets
Key socket Description
Figure 4.2 Protocol family constants for socket function
• The socket functions are then defined as taking a pointer to the generic socket address structure, as shown here in the ANSI C function prototype for the bind function. • This requires that any calls to these functions must cast the pointer to the protocol-specific socket address structure to be a pointer to a generic socket address structure.
socket Function
#include <sys/socket.h> int socket (int family, int type, int protocol); /* Returns: non-negative descriptor if OK, -1 on error */
TCP Stream Socket
#include <sys/socket.h> int bind (int sockfd, const struct sockaddr *myaddr, socklen_t addrlen); /* Returns: 0 if OK,-1 on error */
Generic Socket Address Structure