辅助函数:Linux TCP socket

Linux下辅助函数 TCP socket:




/**//* socklib.c


*


* This file contains functions lots when writing internat


* client/server programs. The two main functions here are:


*


* int make_srver_socket(portnum) return server socket


*


* int make_server_socket_q(portnum,backlog)


*


* int connect_to_server(char *hostname,int portnum)


*/


#include <stdio.h>


#include <unistd.h>


#include <sys/types.h>


#include <sys/socket.h>


#include <netinet/in.h>


#include <netdb.h>


#include <time.h>


#include <string.h>




#define HOSTLEN 256


#define BACKLOG 1




int make_server_socket_q(int,int);






int make_server_socket(int portnum) ...{


return make_server_socket_q(portnum,BACKLOG);


}






int make_server_socket_q(int portnum,int backlog) ...{


struct sockaddr_in saddr; // build out address here


struct hostent *hp; // this is part of our


char hostname[HOSTLEN]; // address


int sock_id; // the socket




sock_id = socket(PF_INET,SOCK_STREAM,0); // get a socket




if(sock_id == -1) ...{


perror("Creare socket error");


return -1;


}




// build address and build it to socket


bzero((void *)&saddr,sizeof(saddr)); // clear out struct


gethostname(hostname,HOSTLEN); // where am I?


hp = gethostbyname(hostname); // get info about host




bcopy((void *)hp -> h_addr,(void *)&saddr.sin_addr,


hp -> h_length);


saddr.sin_port = htons(portnum); // fille in socket port


if(bind(sock_id,(struct sockaddr *)&saddr,




sizeof(saddr)) != 0) ...{


perror("Bind socket error");


return -1;


}




// arrange for incoming calls




if(listen(sock_id,backlog) != 0) ...{


perror("Listen socker error");


return -1;


}




return sock_id;


}






int connect_to_server(char *host,int portnum) ...{


int sock;


struct sockaddr_in servadd; // the number to call


struct hostent *hp; // used to get number




// Step 1:Get a socket


sock = socket(AF_INET,SOCK_STREAM,0);




if(sock == -1) ...{


perror("Create socket error");


return -1;


}




// Step 2:connect to server


bzero(&servadd,sizeof(servadd)); // zero the address


hp = gethostbyname(host); // lookup host's ip #


if(hp == NULL)


return -1;


bcopy(hp -> h_addr,(struct sockaddr *)&servadd.sin_addr,


hp -> h_length);


servadd.sin_port = htons(portnum); // fill in port number


servadd.sin_family = AF_INET; // fill in socket type




if(connect(sock,(struct sockaddr *)&servadd,




sizeof(servadd)) != 0) ...{


perror("Connect socket error");


return -1;


}




return sock;


}