一、针对ECHO服务的TCP客户软件的实现

1.网络拓扑结构：

2.源码：

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

#define LINELEN 128
extern int errno;

int TCPecho(const char *host, const char *service);
int errexit(const char *format,...);
int connectsock(const char *host, const char *service, const char *transport );
int connectTCP(const char *host, const char *service);

int main(int argc, char *argv[]){
? ? char *host= "localhost";
? ? char *service= "echo";
? ? switch(argc){
case 1:
? ? host = "localhost";
? ? break;
case 3:
? ? service = argv[2];
case 2:
? ? host=argv[1];
? ? break;
default:
? ? fprintf(stderr,"usage:TCPecho[host[port]]\n");
? ? exit(1);
? ? }
? ? TCPecho(host,service);
? ? exit(0);
}
int TCPecho(const char *host,const char *service){
? ? char buf[LINELEN+1];
? ? int s,n;
? ? int outchars, inchars;
? ? s=connectTCP(host, service);
? ? while(fgets(buf,sizeof(buf),stdin)){
? ? ? ? buf[LINELEN]='\0';
? ? ? ? outchars=strlen(buf);
? ? ? ? (void)write(s,buf,outchars);
? ? ? ? for(inchars=0;inchars? ? ? ? ? ? n=read(s,&buf[inchars],outchars-inchars);
? ? ? ? ? ? if(n<0)
? ? ? ? ? ? ? ? ? ? errexit("socker read failed: %s\n",strerror(errno));
? ? ? ? }
? ? ? ? fputs(buf,stdout);
? ? }
}
int errexit(const char *format,...){
? ? va_list arg;
? ? va_start(arg, format);
? ? vfprintf(stderr,format,arg);
? ? va_end(arg);
? ? exit(1);
}
int connectsock(const char *host, const char *service, const char *transport )
/*
?* Arguments:
?*? ? ? host? ? ? - name of host to which connection is desired
?*? ? ? service? - service associated with the desired port
?*? ? ? transport - name of transport protocol to use ("tcp" or "udp")
?*/
{
? ? struct hostent? *phe;? /* pointer to host information entry? ? */
? ? struct servent? *pse;? /* pointer to service information entry */
? ? struct protoent *ppe;? /* pointer to protocol information entry*/
? ? struct sockaddr_in sin; /* an Internet endpoint address? ? */
? ? int s, type;? ? /* socket descriptor and socket type? ? */

? ? memset(&sin, 0, sizeof(sin));
? ? sin.sin_family = AF_INET;

? ? /* Map service name to port number */
? ? if ( pse = getservbyname(service, transport) )
? ? ? ? sin.sin_port = pse->s_port;
? ? else if ((sin.sin_port=htons((unsigned short)atoi(service))) == 0)
? ? ? ? errexit("can't get \"%s\" service entry\n", service);

? ? /* Map host name to IP address, allowing for dotted decimal */
? ? if ( phe = gethostbyname(host) )
? ? ? ? memcpy(&sin.sin_addr, phe->h_addr, phe->h_length);
? ? else if ( (sin.sin_addr.s_addr = inet_addr(host)) == INADDR_NONE )
? ? ? ? errexit("can't get \"%s\" host entry\n", host);

? ? /* Map transport protocol name to protocol number */
? ? if ( (ppe = getprotobyname(transport)) == 0)
? ? ? ? errexit("can't get \"%s\" protocol entry\n", transport);

? ? /* Use protocol to choose a socket type */
? ? if (strcmp(transport, "udp") == 0)
? ? ? ? type = SOCK_DGRAM;
? ? else
? ? ? ? type = SOCK_STREAM;

? ? /* Allocate a socket */
? ? s = socket(PF_INET, type, ppe->p_proto);
? ? if (s < 0)
? ? ? ? errexit("can't create socket: %s\n", strerror(errno));

? ? /* Connect the socket */
? ? if (connect(s, (struct sockaddr *)&sin, sizeof(sin)) < 0)
? ? ? ? errexit("can't connect to %s.%s: %s\n", host, service,
? ? ? ? ? ? strerror(errno));
? ? return s;
}
int connectTCP(const char *host, const char *service){
? ? return connectsock(host,service,"tcp");
}

二、针对echo服务的并发的面向连接的服务器软件的实现

1.网络拓扑结构：

2.源码：

#define _USE_BSD
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include