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/* $Id: utils.c,v 1.38 2003-03-14 06:15:27 rjkaes Exp $
*
* Misc. routines which are used by the various functions to handle strings
* and memory allocation and pretty much anything else we can think of. Also,
* the load cutoff routine is in here. Could not think of a better place for
* it, so it's in here.
*
* Copyright (C) 1998 Steven Young
* Copyright (C) 1999,2001,2003 by
* Robert James Kaes (rjkaes@flarenet.com)
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include "tinyproxy.h"
#include "conns.h"
#include "heap.h"
#include "http_message.h"
#include "utils.h"
/*
* Build the data for a complete HTTP & HTML message for the client.
*/
int
send_http_message(struct conn_s *connptr, int http_code,
const char *error_title, const char *message)
{
static char* headers[] = {
"Server: " PACKAGE "/" VERSION,
"Content-type: text/html",
"Connection: close"
};
http_message_t msg;
msg = http_message_create(http_code, error_title);
if (msg == NULL)
return -1;
http_message_add_headers(msg, headers, 3);
http_message_set_body(msg, message, strlen(message));
http_message_send(msg, connptr->client_fd);
http_message_destroy(msg);
return 0;
}
/*
* Safely creates filename and returns the low-level file descriptor.
*/
int
create_file_safely(const char *filename, unsigned int truncate_file)
{
struct stat lstatinfo;
int fildes;
/*
* lstat() the file. If it doesn't exist, create it with O_EXCL.
* If it does exist, open it for writing and perform the fstat()
* check.
*/
if (lstat(filename, &lstatinfo) < 0) {
/*
* If lstat() failed for any reason other than "file not
* existing", exit.
*/
if (errno != ENOENT) {
fprintf(stderr,
"%s: Error checking file %s: %s\n",
PACKAGE, filename, strerror(errno));
return -EACCES;
}
/*
* The file doesn't exist, so create it with O_EXCL to make
* sure an attacker can't slip in a file between the lstat()
* and open()
*/
if ((fildes =
open(filename, O_RDWR | O_CREAT | O_EXCL, 0600)) < 0) {
fprintf(stderr,
"%s: Could not create file %s: %s\n",
PACKAGE, filename, strerror(errno));
return fildes;
}
} else {
struct stat fstatinfo;
int flags;
flags = O_RDWR;
if (!truncate_file)
flags |= O_APPEND;
/*
* Open an existing file.
*/
if ((fildes = open(filename, flags)) < 0) {
fprintf(stderr,
"%s: Could not open file %s: %s\n",
PACKAGE, filename, strerror(errno));
return fildes;
}
/*
* fstat() the opened file and check that the file mode bits,
* inode, and device match.
*/
if (fstat(fildes, &fstatinfo) < 0
|| lstatinfo.st_mode != fstatinfo.st_mode
|| lstatinfo.st_ino != fstatinfo.st_ino
|| lstatinfo.st_dev != fstatinfo.st_dev) {
fprintf(stderr,
"%s: The file %s has been changed before it could be opened\n",
PACKAGE, filename);
close(fildes);
return -EIO;
}
/*
* If the above check was passed, we know that the lstat()
* and fstat() were done on the same file. Now we check that
* there's only one link, and that it's a normal file (this
* isn't strictly necessary because the fstat() vs lstat()
* st_mode check would also find this)
*/
if (fstatinfo.st_nlink > 1 || !S_ISREG(lstatinfo.st_mode)) {
fprintf(stderr,
"%s: The file %s has too many links, or is not a regular file: %s\n",
PACKAGE, filename, strerror(errno));
close(fildes);
return -EMLINK;
}
/*
* Just return the file descriptor if we _don't_ want the file
* truncated.
*/
if (!truncate_file)
return fildes;
/*
* On systems which don't support ftruncate() the best we can
* do is to close the file and reopen it in create mode, which
* unfortunately leads to a race condition, however "systems
* which don't support ftruncate()" is pretty much SCO only,
* and if you're using that you deserve what you get.
* ("Little sympathy has been extended")
*/
#ifdef HAVE_FTRUNCATE
ftruncate(fildes, 0);
#else
close(fildes);
if ((fildes =
open(filename, O_RDWR | O_CREAT | O_TRUNC, 0600)) < 0) {
fprintf(stderr,
"%s: Could not open file %s: %s.",
PACKAGE, filename, strerror(errno));
return fildes;
}
#endif /* HAVE_FTRUNCATE */
}
return fildes;
}
/*
* Write the PID of the program to the specified file.
*/
int
pidfile_create(const char *filename)
{
int fildes;
FILE *fd;
/*
* Create a new file
*/
if ((fildes = create_file_safely(filename, TRUE)) < 0)
return fildes;
/*
* Open a stdio file over the low-level one.
*/
if ((fd = fdopen(fildes, "w")) == NULL) {
fprintf(stderr,
"%s: Could not write PID file %s: %s.",
PACKAGE, filename, strerror(errno));
close(fildes);
unlink(filename);
return -EIO;
}
fprintf(fd, "%ld\n", (long) getpid());
fclose(fd);
return 0;
}
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