#include <u.h>
#include <libc.h>
#include <auth.h>

int	eof;		/* send an eof if true */
char	*note = "die: yankee dog";

void	rex(int, char*, char*);
void	dkexec(int, char*, char*);
void	tcpexec(int, char*, char*);
int	call(char *, char*, char*, char**);
char	*buildargs(char*[]);
int	send(int);
void	error(char*, char*);

void
usage(void)
{
	fprint(2, "usage: %s [-e] net!host command...\n", argv0);
	exits("usage");
}

void
main(int argc, char *argv[])
{
	char *host, *addr, *args;
	int fd;

	eof = 1;
	ARGBEGIN{
	case 'e':
		eof = 0;
		break;
	default:
		usage();
	}ARGEND

	if(argc < 2)
		usage();
	host = argv[0];
	args = buildargs(&argv[1]);

	/* generic attempts */
	fd = call(0, host, "rexexec", &addr);
	if(fd >= 0)
		rex(fd, addr, args);
	fd = call(0, host, "exec", &addr);
	if(fd >= 0)
		dkexec(fd, addr, args);

	/* specific attempts */
	fd = call("tcp", host, "shell", &addr);
		tcpexec(fd, addr, args);
	fd = call("dk", host, "exec", &addr);	
	if(fd >= 0)
		dkexec(fd, addr, args);

	error("can't dial", host);
	exits(0);
}

int
call(char *net, char *host, char *service, char **na)
{
	*na = netmkaddr(host, net, service);
	return dial(*na, 0, 0, 0);
}

void
rex(int fd, char *addr, char *cmd)
{
	char buf[4096], *err;
	int kid, n;

	if(err = auth(fd, addr)){
		close(fd);
		if(strcmp(err, "can't read server challenge") == 0)
			return;
		error(err, 0);
	}
	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(kid, note);/**/
	exits(0);
}

void
dkexec(int fd, char *addr, char *cmd)
{
	char buf[4096];
	int kid, n;

	if(read(fd, buf, 1)!=1 || *buf!='O'
	|| read(fd, buf, 1)!=1 || *buf!='K'){
		close(fd);
		error("can't authenticate to", addr);
	}

	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(kid, note);/**/
	exits(0);
}

void
tcpexec(int fd, char *addr, char *cmd)
{
	char *u, buf[4096];
	int kid, n;

	/*
	 *  do the ucb authentication and send command
	 */
	u = getuser();
	if(write(fd, "", 1)<0 || write(fd, u, strlen(u)+1)<0
	|| write(fd, u, strlen(u)+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(kid, note);/**/
	exits(0);
}

int
send(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 */
}

void
error(char *s, char *z)
{
	if(z == 0)
		fprint(2, "%s: %s\n", argv0, s);
	else
		fprint(2, "%s: %s %s\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;
}