#include <u.h>#include <libc.h>#include <auth.h>#include "authlocal.h" static char *abmsg = "/dev/authenticate: %r";static char *cgmsg = "client gave up"; intsrvauth(int fd, char *user){	int n, afd;	char trbuf[TICKREQLEN];	char tbuf[2*TICKETLEN]; 	/* get ticket request from kernel and pass to client */	afd = open("/dev/authenticate", ORDWR);	if(afd < 0){		werrstr(abmsg);		return -1;	}	n = read(afd, trbuf, TICKREQLEN);	if(n != TICKREQLEN){		close(afd);		werrstr(abmsg);		return -1;	}	if(write(fd, trbuf, TICKREQLEN) < 0){		close(afd);		werrstr(cgmsg);		return -1;	} 	/* get reply from client and pass to kernel */	if(_asreadn(fd, tbuf, TICKETLEN+AUTHENTLEN) < 0){		close(afd);		werrstr(cgmsg);		return -1;	}	if(write(afd, tbuf, TICKETLEN+AUTHENTLEN) < 0){		close(afd);		memset(tbuf, 0, AUTHENTLEN);		write(fd, tbuf, AUTHENTLEN);		werrstr("permission denied");		return -1;	} 	/* get authenticator from kernel and pass to client*/	read(afd, tbuf, AUTHENTLEN);	close(afd);	if(write(fd, tbuf, AUTHENTLEN) < 0){		werrstr("permission denied");		return -1;	} 	strcpy(user, getuser());	return 0;}