Your task is modifythe sever tolisten on an IPv6 socket. You should also change the code so that it is robust against clients failing to resolve.

You can test the sever with telnet, specifying an IP6 address. Recall that ::1 is the loopbackaddress in IPv6.

Sample Server code

#include

#include

#include

#include

#include

#include

#include

#include

#include

int

main(intargc,char*argv[])

{

structaddrinfo*ai;

structaddrinfohints;

memset(&hints,'\0',sizeof(hints));

hints.ai_flags=AI_PASSIVE|AI_ADDRCONFIG;

hints.ai_socktype=SOCK_STREAM;

inte=getaddrinfo(NULL,"echo",&hints,&ai);

if(e!=0)

error(EXIT_FAILURE,0,"getaddrinfo:%s",gai_strerror(e));

intnfds=0;

structaddrinfo*runp=ai;

while(runp!=NULL)

{

++nfds;

runp=runp->ai_next;

}

structpollfdfds[nfds];

for(nfds=0,runp=ai;runp!=NULL;runp=runp->ai_next)

{

fds[nfds].fd=socket(runp->ai_family,runp->ai_socktype,runp->ai_protocol);

if(fds[nfds].fd==-1)

error(EXIT_FAILURE,errno,"socket");

fds[nfds].events=POLLIN;

intopt=1;

setsockopt(fds[nfds].fd,SOL_SOCKET,SO_REUSEADDR,

&opt,sizeof(opt));

if(bind(fds[nfds].fd,

runp->ai_addr,runp->ai_addrlen)!=0)

{

if(errno!=EADDRINUSE)

error(EXIT_FAILURE,errno,"bind");

close(fds[nfds].fd);

}

else

{

if(listen(fds[nfds].fd,SOMAXCONN)!=0)

error(EXIT_FAILURE,errno,"listen");

++nfds;

}

}

freeaddrinfo(ai);

while(1)

{

intn=poll(fds,nfds,-1);

if(n>0)

for(inti=0;i

if(fds[i].revents&POLLIN)

{

structsockaddr_storagerem;

socklen_tremlen=sizeof(rem);

intfd=accept(fds[i].fd,(structsockaddr*)&rem,&remlen);

if(fd!=-1)

{

charbuf1[200];

if(getnameinfo((structsockaddr*)&rem,remlen,

buf1,sizeof(buf1),NULL,0,0)!=0)

strcpy(buf1,"???");

charbuf2[100];

(void)getnameinfo((structsockaddr*)&rem,remlen,

buf2,sizeof(buf2),NULL,0,

NI_NUMERICHOST);

printf("connectionfrom%s(%s) ",buf1,buf2);

charbuf[1000];

ssize_tl=read(fd,buf,sizeof(buf));

write(fd,buf,l);

close(fd);

}

}

}

}

Sample Client Code-

#include

#include

#include

#include

#include

#include

#include

#include

int

main(intargc,char*argv[])

{

intresult=0;

structaddrinfo*ai;

structaddrinfohints;

memset(&hints,'\0',sizeof(hints));

hints.ai_flags=AI_ADDRCONFIG;

hints.ai_socktype=SOCK_STREAM;

inte=getaddrinfo(argv[1],"echo",&hints,&ai);

if(e!=0)

error(EXIT_FAILURE,0,"getaddrinfo:%s",gai_strerror(e));

structaddrinfo*runp=ai;

while(runp!=NULL)

{

intsock=socket(runp->ai_family,runp->ai_socktype,

runp->ai_protocol);

if(sock!=-1)

{

if(connect(sock,

runp->ai_addr,runp->ai_addrlen)==0)

{

char*line=NULL;

size_tlen=0;

ssize_tn=getline(&line,&len,stdin);

write(sock,line,n);

n=read(sock,line,len);

write(STDOUT_FILENO,line,n);

close(sock);

gotoout;

}

close(sock);

}

runp=runp->ai_next;

}

error(0,0,"cannotcontact%s",argv[1]);

result=1;

out:

freeaddrinfo(ai);

returnresult;

}