#include <u.h>#include <libc.h>#include <auth.h> int	eof;		/* send an eof if true */char	*note = "die: yankee dog";char	*ruser; void	rex(int, char*);void	tcpexec(int, char*, char*);int	call(char *, char*, char*, char**);char	*buildargs(char*[]);int	send(int);void	error(char*, char*); voidusage(void){	fprint(2, "usage: %s [-e] net!host command...\n", argv0);	exits("usage");} voidmain(int argc, char *argv[]){	char *host, *addr, *args;	int fd; 	eof = 1;	ARGBEGIN{	case 'e':		eof = 0;		break;	case 'l':		ruser = ARGF();		break;	default:		usage();	}ARGEND 	if(argc < 2)		usage();	host = argv[0];	args = buildargs(&argv[1]); 	/* specific attempts */	fd = call("tcp", host, "shell", &addr);	if(fd >= 0)		tcpexec(fd, addr, args); 	/* generic attempts */	fd = call(0, host, "rexexec", &addr);	if(fd >= 0)		rex(fd, args); 	error("can't dial", host);	exits(0);} intcall(char *net, char *host, char *service, char **na){	*na = netmkaddr(host, net, service);	return dial(*na, 0, 0, 0);} voidrex(int fd, char *cmd){	char buf[4096];	int kid, n;	AuthInfo *ai; 	ai = auth_proxy(fd, auth_getkey, "proto=p9sk2 role=client");	if(ai == nil)		error("auth_proxy", nil);	write(fd, cmd, strlen(cmd)+1); 	kid = send(fd);	while((n=read(fd, buf, sizeof buf))>0)		if(write(1, buf, n)!=n)			error("write error", 0);	sleep(250);	postnote(PNPROC, kid, note);/**/	exits(0);} voidtcpexec(int fd, char *addr, char *cmd){	char *u, buf[4096];	int kid, n;	char *r; 	/*	 *  do the ucb authentication and send command	 */	u = getuser();	r = ruser ? ruser : u;	if(write(fd, "", 1)<0 || write(fd, u, strlen(u)+1)<0	|| write(fd, r, strlen(r)+1)<0 || write(fd, cmd, strlen(cmd)+1)<0){		close(fd);		error("can't authenticate to", addr);	} 	/*	 *  get authentication reply	 */	if(read(fd, buf, 1) != 1){		close(fd);		error("can't authenticate to", addr);	}	if(buf[0] != 0){		while(read(fd, buf, 1) == 1){			write(2, buf, 1);			if(buf[0] == '\n')				break;		}		close(fd);		error("rejected by", addr);	} 	kid = send(fd);	while((n=read(fd, buf, sizeof buf))>0)		if(write(1, buf, n)!=n)			error("write error", 0);	sleep(250);	postnote(PNPROC, kid, note);/**/	exits(0);} intsend(int fd){	char buf[4096];	int n;	int kid;	switch(kid = fork()){	case -1:		error("fork error", 0);	case 0:		break;	default:		return kid;	}	while((n=read(0, buf, sizeof buf))>0)		if(write(fd, buf, n)!=n)			exits("write error");	if(eof)		write(fd, buf, 0); 	exits(0);	return 0;			/* to keep compiler happy */} voiderror(char *s, char *z){	if(z == 0)		fprint(2, "%s: %s: %r\n", argv0, s);	else		fprint(2, "%s: %s %s: %r\n", argv0, s, z);	exits(s);} char *buildargs(char *argv[]){	char *args;	int m, n; 	args = malloc(1);	args[0] = '\0';	n = 0;	while(*argv){		m = strlen(*argv) + 1;		args = realloc(args, n+m +1);		if(args == 0)			error("malloc fail", 0);		args[n] = ' ';	/* smashes old null */		strcpy(args+n+1, *argv);		n += m;		argv++;	}	return args;}