int eof; /* send an eof if true */

#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;
}