Socket address structure in <sys/socket.h>:
struct sockaddr{u_short sa_family; /* address family:
AF_xxx value */char sa_data[14]; /* up to 14 bytes of protocol- */
/* specific address */}
Socket Programming
Socket address structure in <netinet/in.h>:(Internet family)
struct in_addr{u_long s_addr; /* 32-bit netid/hostid */
/* network byte ordered */}
Socket Programming
struct sockaddr_in{short sin_family; /* AF_INET */u_short sin_port; /* 16-bit port
number *//* network byte ordered */
struct in_addr sin_addr; /* 32-bit netid/hostid *//* network byte ordered */
char sin_zero[8]; /* unused */}
Socket Programming
socket : specify the type of communication protocol desired (TCP, UDP etc.)
#include <sys/types.h>#include <sys/socket.h>int socket(int family, int type, int protocol);
family: AF_UNIX (UNIX internal protocol)AF_INET (Internet protocols)AF_NS (Xerox NS protocols) AF_IMPLINK (IMP link layer)
(AF: address family)
Socket Programming
type: SOCK_STREAM (stream socket, TCP)SOCK_DGRAM (datagram socket, UDP)SOCK_RAW (raw socket)SOCK_SEQPACKET (sequenced packet
socket)SOCK_RDM (reliably delivered message
socket) (not implemented yet)
protocol: typically set to 0 for most user applications
The output of the system call is the socket descriptor.
Socket Programming
bind: assign a name to an unnamed socket
#include <sys/types.h>#include <sys/socket.h>int bind(int sockfd, struct sockaddr *myaddr, int addrlen);
sockfd: socket descriptor (return by*myaddr: a pointer to a protocol-specific addressaddrlen: the size of this address structure
The output > 0 if success; otherwise, it fails.
Socket Programming
connect: establish a connection with a server
#include <sys/types.h>#include <sys/socket.h>int connect (int sockfd, struct sockaddr *servaddr, int addrlen);
same as the system call bind.
The output > 0 if success; otherwise, it fails.
Socket Programming
listen: is used by a connection-oriented server to indicate that it is willing to receive connections#include <sys/types.h>#include <sys/socket.h>int listen (int sockfd, struct backlog);
backlog: specify how many connection requests can be queued by the system while it waits for the server to execute the accept system call (default as 5).
The output > 0 if success; otherwise, it fails.
Socket Programming
accept: take the first connection request on the queue and create another socket with the same properties as sockfd.
#include <sys/types.h>#include <sys/socket.h>int accept (int sockfd, struct sockaddr *peer, int *addrlen);
peer: the address of connected peer process (the client).addrlen: the size of peer.
The output of the system call is the socket descriptor.
Socket Programming
send, sendto, recv and recvform
#include <sys/types.h>#include <sys/socket.h>int send(int sockfd, char *buff, int nbytes, int flags);int sendto(int sockfd, char *buff, int nbytes, int flags, struct sockaddr *to, int addrlen);int recv(int sockfd, char *buff, int nbytes, int flags);int recvfrom(int sockfd, char *buff, int nbytes, int flags, struct sockaddr *to, int addrlen);
flag: usually zero
Socket Programming
close: close a socket
#include <sys/types.h>#include <sys/socket.h>int close (int fd);
bzero: writes the specified number of null bytes to the specified destination.
bzero(char *dest, int nbytes);
Socket Programming
htonl: convert host-to-network to long integer
htons: convert host-to-network to short integer
#include <sys/types.h>#include <netinet/in.h>u_long htonl(u_long hostlong);u_short htons(u_long hostshort);
Socket Programming
inet_addr: convert a character string in dotted-decimal notation to a 32-bit Internet address
#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>
unsigned long inet_addr(char *ptr);
Socket Programming
read ( )
connect ( )
socket ( )
write ( )
socket ( )
bind ( )
listen ( )
read ( )
accept ( )
write ( )
blocks until connection from client
process request
connection establishment
data (request)
data (reply)
Connection-oriented Protocol
Server
Client
Socket Programming
ConnectionlessProtocol
Server
Client
recvfrom ( )
bind ( )
socket ( )
sendto ( )data (request)
data (reply)
socket ( )
bind ( )
recvfrom ( )
sendto ( )
blocks until data received from a client
process request
Socket Programming
int tcp_serv() /* server program: setup a TCP connection */{ int sockfd, newsockfd, clilen; struct sockaddr_in cli_addr, serv_addr;
if ((sockfd = socket (AF_INET, SOCK_STREAM, 0)) < 0) err_dump(“server: can't open stream socket”);
bzero((char *) &serv_addr, sizeof(serv_addr)); serv_addr.sin_family = AF_INET; serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); /* INADDR_ANY: any Internet interface on the system */
Socket Programming
serv_addr.sin_port = htons(SERV_TCP_PORT);
if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
err_dump(“server: can't bind local address”);
listen(socfd, 5); clilen = sizeof(cli_addr); if ((newsockfd = accept(sockfd, (struct sockaddr *)
&cli_addr, &clilen)) < 0) err_dump(“server: accept error”);}
Socket Programming
int tcp_client() /* client program: setup a TCP connection */{ int sockfd, newsockfd, clilen; struct sockaddr_in serv_addr;
bzero((char *) &serv_addr, sizeof(serv_addr)); serv_addr.sin_family = AF_INET; serv_addr.sin_addr.s_addr = inet_addr(SERV_HOST_ADDR); serv_addr.sin_port = htons(SERV_TCP_PORT);
Socket Programming
if ((sockfd = socket (AF_INET, SOCK_STREAM, 0)) < 0) err_sys(“client: can't open stream socket”);
if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
err_sys(“client: can't bind local address”);
/* do the transmission */
close(sockfd);}
Socket Programming
tcp_send(s_act, msg_ptr, msg_len) /* ipc_send: send data message “msg” within stream domain */ int s_act; /* actual socket descriptor of connection */ char *msg_ptr; /* pointer to data msg unit */ int msg_len; /* length of data msg unit */{ int cc = 0, rc; cc = send(s_act, msg_ptr, msg_len, 0); /*UNIX system
call */ if (cc == -1) {perror("send: ! "); rc = cc; } /* error report */ else rc = OK (=1); return (rc);}
Socket Programming
tcp_receive(s_act, buf_ptr, buf_len) /* receive data within UNIX*/ int s_act; /* socket descriptor of ipc connection */ union u_du *buf_ptr; /* pointer to message buffer */ int *buf_len; /* length of message buffer */{ int cc, rc; cc = recv(s_act, buf_ptr, *buf_len, 0); /* UNIX syst call */ if (cc == -1) { perror("recv: "); rc = cc; } else {*buf_len = cc; rc = OK (= 1); } return (rc);
}
Socket Programming
int udp_serv() /* server program: setup a UDP connection */{ int sockfd, newsockfd, clilen; struct sockaddr_in cli_addr, serv_addr;
if ((sockfd = socket (AF_INET, SOCK_DGRAM, 0)) < 0) err_dump(“server: can't open datagram socket”);
bzero((char *) &serv_addr, sizeof(serv_addr)); serv_addr.sin_family = AF_INET; serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); /* INADDR_ANY: any Internet interface on the system */
Socket Programming
serv_addr.sin_port = htons(SERV_UDP_PORT);
if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
err_dump(“server: can't bind local address”);
/* do the transmission */}
Socket Programming
int udp_client() /* client program: setup a UDP connection */{ int sockfd, newsockfd, clilen; struct sockaddr_in cli_addr, serv_addr;
bzero((char *) &serv_addr, sizeof(serv_addr)); serv_addr.sin_family = AF_INET; serv_addr.sin_addr.s_addr = inet_addr(SERV_HOST_ADDR); serv_addr.sin_port = htons(SERV_UDP_PORT);
if ((sockfd = socket (AF_INET, SOCK_DGRAM, 0)) < 0) err_dump(“client: can't open datagram socket”);
Socket Programming
bzero((char *) &cli_addr, sizeof(cli_addr)); cli_addr.sin_family = AF_INET; cli_addr.sin_addr.s_addr = htonl(INADDR_ANY); cli_addr.sin_port = htons(0);
if (bind(sockfd, (struct sockaddr *) &cli_addr, sizeof(cli_addr)) < 0)
err_dump(“client: can't bind local address”);
/* do the transmission */
close(sockfd);}
Socket Programming
udp_send( msg_ptr, msg_len, addr_ptr, addr_len ) char *msg_ptr; /* pointer to message */ int msg_len; /* length of message */ struct sockaddr_in *addr_ptr; /* socket address */ int addr_len; /* length of socket address */{ int cc; addr_ptr.sin_addr.s_addr = htonl(st_addr); /*convert address*/ cc = sendto(s_udp, msg_ptr, msg_len, 0 addr_ptr, addr_len ); if (cc == -1) {perror("sendto: "); return(cc);} else return(OK);}
Socket Programming
udp_receive(msg_ptr, msg_len, addr_ptr, addr_len) char *msg_ptr; /* pointer to message
“msg” */ int msg_len; /* length of message */ struct sockaddr_in *addr_ptr; /* socket address */ int addr_len; /* length of socket address */{ int cc; cc = recvfrom(s_udp, msg_ptr, *msg_len, 0, addr_ptr,
addr_len ); if (cc == -1) {perror("recvfrom: "); return(cc); } else return(OK);}
Socket Programming
#define _REENTRANT #include <stdio.h> #include <thread.h> #define NUM_THREADS 12 void *change_global_data(void *); /* for thr_create()
*/ main(int argc,char * argv[]) { int i=0; for (i=0; i< NUM_THREADS; i++) { thr_create(NULL, 0, change_global_data,
NULL, 0, NULL); } while ((thr_join(NULL, NULL, NULL) == 0)); }
void * change_global_data(void *null) { static mutex_t Global_mutex; static int Global_data = 0; mutex_lock(&Global_mutex); Global_data++; sleep(1); printf("%d is global data\n",Global_data); mutex_unlock(&Global_mutex); return NULL; }
Thread Programming (Try the program)
Use online help to find out
the information about
thread programming.
Try:
man mutex
man thr_create
man thr_join
…...