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/*
** Copyright 1998 - 2000 Double Precision, Inc. See COPYING for
** distribution information.
*/
/* Based on code by Christian Loitsch <courier-imap@abc.fgecko.com> */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
/* for fork */
#include <sys/types.h>
/* used to avoid zombies */
#include <signal.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/select.h>
#include "auth.h"
#include "authcustom.h"
#include "courierauthdebug.h"
#include "courierauthdebug.h"
#include "authpipelib.h"
#include "authpiperc.h"
static int lastIn = -1;
static int lastOut = -1;
static pid_t childPID = -1;
static void eliminatePipe(pid_t child);
static void execChild(int to[], int from[])
{
DPRINTF("executing %s", PIPE_PROGRAM);
close(STDIN_FILENO); dup2(to[0], STDIN_FILENO);
close(STDOUT_FILENO); dup2(from[1], STDOUT_FILENO);
close(to[0]); close(to[1]); close(from[0]); close(from[1]);
execl(PIPE_PROGRAM, PIPE_PROGRAM, NULL);
DPRINTF("pipe: failed to execute %s: %s",PIPE_PROGRAM, strerror(errno));
exit(1);
}
void closePipe(void)
{
DPRINTF("closing pipe");
if (lastIn >= 0) { close(lastIn); lastIn = -1; }
if (lastOut >= 0) { close (lastOut); lastOut = -1; }
if (childPID > 1) { eliminatePipe(childPID); childPID = -1; }
}
static int forkPipe(int *dataIn, int *dataOut, pid_t *child)
{
int to[2], from[2];
/* let's create 2 pipes */
if(pipe(to) < 0) {
DPRINTF("pipe: failed to create pipe: %s", strerror(errno));
return 1;
}
if(pipe(from) < 0) {
DPRINTF("pipe: failed to create pipe: %s", strerror(errno));
close(to[0]); close(to[1]);
return 1;
}
DPRINTF("attempting to fork");
*child = fork();
if(*child < 0) {
DPRINTF("pipe: failed to fork: %s", strerror(errno));
close(to[0]); close(to[1]); close(from[0]); close(from[1]);
return 1;
}
/* child */
if(*child == 0) execChild(to, from);
/* parent */
DPRINTF("Pipe auth. started Pipe-program (pid %d)", *child);
close(to[0]); close(from[1]);
*dataIn = from[0]; *dataOut = to[1];
return 0;
}
/* kills and waits for child
* in a quite inefficient way, but this shouldn't happen very often */
static void eliminatePipe(pid_t child)
{
unsigned int seconds;
/* let's first look, if child is already terminated */
DPRINTF("trying to wait for child (WNOHANG) (pid %d)", child);
if (waitpid(child, NULL, WNOHANG) > 0) return;
DPRINTF("sleep 2 seconds and try again to wait for pid %d", child);
/* let's give the pipe-program a few seconds to terminate */
sleep(2); /* don't care if interrupted earlier */
if (waitpid(child, NULL, WNOHANG) > 0) return;
/* let's TERM it */
DPRINTF("killing (SIGTERM) child pid %d", child);
kill(child, SIGTERM);
/* give it a few seconds */
for (seconds = 10; seconds > 0; sleep(1), seconds--)
if (waitpid(child, NULL, WNOHANG) > 0) return;
/* ok, let's KILL it */
DPRINTF("killing (SIGKILL) child pid %d", child);
if (kill(child, SIGKILL) == 0)
{
/* and wait, unless we have a kernel bug, it MUST terminate */
DPRINTF("waitpiding for child pid (blocking!) %d)", child);
waitpid(child, NULL, 0);
}
else
{
DPRINTF("error when sending sigkill to %d", child);
if (errno != ESRCH) return;
/* strange, we can not kill our own child with SIGKILL*/
/* errno indicates process does not exist, maybe it's dead
* by now, let's try 1 final time, else, ignore it */
DPRINTF("maybe because already dead (pid: %d)", child);
waitpid(child, NULL, WNOHANG);
}
}
int getPipe(int *dataIn, int *dataOut)
{
int rv;
if (childPID > 1)
{
/* Simple test if the child is still usable: do a read
** poll on dataIn. If the child has closed the pipe,
** or there is spurious data, the fd will be ready. */
fd_set fdr;
struct timeval tv;
FD_ZERO(&fdr);
FD_SET(lastIn, &fdr);
tv.tv_sec=0;
tv.tv_usec=0;
rv = select(lastIn+1, &fdr, 0, 0, &tv);
if (rv == 0)
{
DPRINTF("reusing pipe, with in: %d out: %d", lastIn, lastOut);
*dataIn = lastIn;
*dataOut = lastOut;
return 0;
}
if (rv < 0)
perror("authpipe: getPipe: select");
else
{
DPRINTF("child died or sent spurious data (pid: %d)", childPID);
}
}
/* ok pipe was not usable; either this is the first call, or
* the pipe broke the connection.
* We have to clean up and start a new one */
closePipe();
DPRINTF("forking new one");
rv = forkPipe(&lastIn, &lastOut, &childPID);
if (rv)
{
DPRINTF("couldn't fork new pipe");
lastIn = -1;
lastOut = -1;
childPID = -1;
}
else
{
DPRINTF("new pipe has in: %d, out: %d", lastIn, lastOut);
*dataIn = lastIn;
*dataOut = lastOut;
}
return rv;
}
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