*
* Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
*
- * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2, see file LICENSE in this source tree.
*/
/*
* A typical usage of BB lpd looks as follows:
- * # tcpsvd -E 0 515 lpd SPOOLDIR [HELPER-PROG [ARGS...]]
- *
- * This means a network listener is started on port 515 (default for LP protocol).
- * When a client connection is made (via lpr) lpd first change its working directory to SPOOLDIR.
- *
- * SPOOLDIR is the spool directory which contains printing queues
+ * # tcpsvd -E 0 515 lpd [SPOOLDIR] [HELPER-PROG [ARGS...]]
+ *
+ * This starts TCP listener on port 515 (default for LP protocol).
+ * When a client connection is made (via lpr) lpd first changes its
+ * working directory to SPOOLDIR (current dir is the default).
+ *
+ * SPOOLDIR is the spool directory which contains printing queues
* and should have the following structure:
- *
+ *
* SPOOLDIR/
- * <queue1>
- * ...
- * <queueN>
- *
+ * <queue1>
+ * ...
+ * <queueN>
+ *
* <queueX> can be of two types:
- * A. a printer character device or an ordinary file a link to such;
- * B. a directory.
- *
- * In case A lpd just dumps the data it receives from client (lpr) to the
+ * A. a printer character device, an ordinary file or a link to such;
+ * B. a directory.
+ *
+ * In case A lpd just dumps the data it receives from client (lpr) to the
* end of queue file/device. This is non-spooling mode.
- *
- * In case B lpd enters spooling mode. It reliably saves client data along with control info
- * in two unique files under the queue directory. These files are named dfAXXXHHHH and cfAXXXHHHH,
- * where XXX is the job number and HHHH is the client hostname. Unless a printing helper application
+ *
+ * In case B lpd enters spooling mode. It reliably saves client data along
+ * with control info in two unique files under the queue directory. These
+ * files are named dfAXXXHHHH and cfAXXXHHHH, where XXX is the job number
+ * and HHHH is the client hostname. Unless a printing helper application
* is specified lpd is done at this point.
- *
- * If HELPER-PROG (with optional arguments) is specified then lpd continues to process client data:
- * 1. it reads and parses control file (cfA...). The parse process results in setting environment
- * variables whose values were passed in control file; when parsing is complete, lpd deletes
- * control file.
- * 2. it spawns specified helper application. It is then the helper application who is responsible
- * for both actual printing and deleting processed data file.
- *
- * A good lpr passes control files which when parsed provide the following variables:
+ *
+ * NB: file names are produced by peer! They actually may be anything at all.
+ * lpd only sanitizes them (by removing most non-alphanumerics).
+ *
+ * If HELPER-PROG (with optional arguments) is specified then lpd continues
+ * to process client data:
+ * 1. it reads and parses control file (cfA...). The parse process
+ * results in setting environment variables whose values were passed
+ * in control file; when parsing is complete, lpd deletes control file.
+ * 2. it spawns specified helper application. It is then
+ * the helper application who is responsible for both actual printing
+ * and deleting of processed data file.
+ *
+ * A good lpr passes control files which when parsed provides the following
+ * variables:
* $H = host which issues the job
* $P = user who prints
* $C = class of printing (what is printed on banner page)
* $J = the name of the job
* $L = print banner page
* $M = the user to whom a mail should be sent if a problem occurs
+ *
+ * We specifically filter out and NOT provide:
* $l = name of datafile ("dfAxxx") - file whose content are to be printed
- *
+ *
+ * lpd provides $DATAFILE instead - the ACTUAL name
+ * of the datafile under which it was saved.
+ * $l would be not reliable (you would be at mercy of remote peer).
+ *
* Thus, a typical helper can be something like this:
* #!/bin/sh
- * cat "$l" >/dev/lp0
- * mv -f "$l" save/
- *
+ * cat ./"$DATAFILE" >/dev/lp0
+ * mv -f ./"$DATAFILE" save/
*/
+//config:config LPD
+//config: bool "lpd (5.3 kb)"
+//config: default y
+//config: help
+//config: lpd is a print spooling daemon.
+
+//applet:IF_LPD(APPLET(lpd, BB_DIR_USR_SBIN, BB_SUID_DROP))
+
+//kbuild:lib-$(CONFIG_LPD) += lpd.o
+
+//usage:#define lpd_trivial_usage
+//usage: "SPOOLDIR [HELPER [ARGS]]"
+//usage:#define lpd_full_usage "\n\n"
+//usage: "SPOOLDIR must contain (symlinks to) device nodes or directories"
+//usage: "\nwith names matching print queue names. In the first case, jobs are"
+//usage: "\nsent directly to the device. Otherwise each job is stored in queue"
+//usage: "\ndirectory and HELPER program is called. Name of file to print"
+//usage: "\nis passed in $DATAFILE variable."
+//usage: "\nExample:"
+//usage: "\n tcpsvd -E 0 515 softlimit -m 999999 lpd /var/spool ./print"
+
#include "libbb.h"
// strip argument of bad chars
return str;
}
-// we can use leaky setenv since we are about to exec or exit
-static void exec_helper(char **filenames, char **argv) ATTRIBUTE_NORETURN;
-static void exec_helper(char **filenames, char **argv)
-{
- char *p, *q;
- char var[2];
-
- // read and delete ctrlfile
- q = xmalloc_open_read_close(filenames[0], NULL);
- unlink(filenames[0]);
- // provide datafile name
- xsetenv("DATAFILE", filenames[1]);
- // parse control file by "\n"
- while ((p = strchr(q, '\n')) != NULL
- && isalpha(*q)
- ) {
- *p++ = '\0';
- // here q is a line of <SYM><VALUE>
- // let us set environment string <SYM>=<VALUE>
- var[0] = *q++;
- var[1] = '\0';
- xsetenv(var, q);
- // next line, plz!
- q = p;
- }
- // we are the helper, we wanna be silent.
- // this call reopens stdio fds to "/dev/null"
- // (no daemonization is done)
- bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO | DAEMON_ONLY_SANITIZE, NULL);
- BB_EXECVP(*argv, argv);
- exit(0);
-}
-
static char *xmalloc_read_stdin(void)
{
// SECURITY:
size_t max = 4 * 1024; // more than enough for commands!
- return xmalloc_reads(STDIN_FILENO, NULL, &max);
+ return xmalloc_reads(STDIN_FILENO, &max);
}
int lpd_main(int argc, char *argv[]) MAIN_EXTERNALLY_VISIBLE;
-int lpd_main(int argc ATTRIBUTE_UNUSED, char *argv[])
+int lpd_main(int argc UNUSED_PARAM, char *argv[])
{
int spooling = spooling; // for compiler
- int seen;
char *s, *queue;
char *filenames[2];
// error messages of xfuncs will be sent over network
xdup2(STDOUT_FILENO, STDERR_FILENO);
- filenames[0] = NULL; // ctrlfile name
- filenames[1] = NULL; // datafile name
+ // nullify ctrl/data filenames
+ memset(filenames, 0, sizeof(filenames));
// read command
s = queue = xmalloc_read_stdin();
// queue is a directory -> chdir to it and enter spooling mode
spooling = chdir(queue) + 1; // 0: cannot chdir, 1: done
- seen = 0;
- // we don't free(queue), we might need it later
+ // we don't free(s), we might need "queue" var later
while (1) {
char *fname;
int fd;
- // int is easier than ssize_t: can use xatoi_u,
+ // int is easier than ssize_t: can use xatoi_positive,
// and can correctly display error returns (-1)
int expected_len, real_len;
// N.B. we bail out on any error
s = xmalloc_read_stdin();
if (!s) { // (probably) EOF
- if (spooling /* && 6 != spooling - always true */) {
- // we didn't see both ctrlfile & datafile!
- goto err_exit;
+ char *p, *q, var[2];
+
+ // non-spooling mode or no spool helper specified
+ if (!spooling || !*argv)
+ return EXIT_SUCCESS; // the only non-error exit
+ // spooling mode but we didn't see both ctrlfile & datafile
+ if (spooling != 7)
+ goto err_exit; // reject job
+
+ // spooling mode and spool helper specified -> exec spool helper
+ // (we exit 127 if helper cannot be executed)
+ var[1] = '\0';
+ // read and delete ctrlfile
+ q = xmalloc_xopen_read_close(filenames[0], NULL);
+ unlink(filenames[0]);
+ // provide datafile name
+ // we can use leaky setenv since we are about to exec or exit
+ xsetenv("DATAFILE", filenames[1]);
+ // parse control file by "\n"
+ while ((p = strchr(q, '\n')) != NULL && isalpha(*q)) {
+ *p++ = '\0';
+ // q is a line of <SYM><VALUE>,
+ // we are setting environment string <SYM>=<VALUE>.
+ // Ignoring "l<datafile>", exporting others:
+ if (*q != 'l') {
+ var[0] = *q++;
+ xsetenv(var, q);
+ }
+ q = p; // next line
}
- // one of only two non-error exits
- return EXIT_SUCCESS;
+ // helper should not talk over network.
+ // this call reopens stdio fds to "/dev/null".
+ bb_daemon_helper(DAEMON_DEVNULL_STDIO);
+ BB_EXECVP_or_die(argv);
}
// validate input.
// we understand only "control file" or "data file" cmds
if (2 != s[0] && 3 != s[0])
goto unsupported_cmd;
- if (seen & (s[0] - 1)) {
- printf("Duplicated subcommand\n");
+ if (spooling & (1 << (s[0]-1))) {
+ puts("Duplicated subcommand");
goto err_exit;
}
- seen &= (s[0] - 1); // bit 1: ctrlfile; bit 2: datafile
// get filename
- *strchrnul(s, '\n') = '\0';
+ chomp(s);
fname = strchr(s, ' ');
if (!fname) {
// bad_fname:
- printf("No or bad filename\n");
+ puts("No or bad filename");
goto err_exit;
}
*fname++ = '\0';
// get length
expected_len = bb_strtou(s + 1, NULL, 10);
if (errno || expected_len < 0) {
- printf("Bad length\n");
+ puts("Bad length");
goto err_exit;
}
if (2 == s[0] && expected_len > 16 * 1024) {
// SECURITY:
// ctrlfile can't be big (we want to read it back later!)
- printf("File is too big\n");
+ puts("File is too big");
goto err_exit;
}
fd = xopen(queue, O_RDWR | O_APPEND);
}
+ // signal OK
+ safe_write(STDOUT_FILENO, "", 1);
+
// copy the file
real_len = bb_copyfd_size(STDIN_FILENO, fd, expected_len);
if (real_len != expected_len) {
expected_len, real_len);
goto err_exit;
}
- // get ACK and see whether it is NUL (ok)
- if (safe_read(STDIN_FILENO, s, 1) != 1 || s[0] != 0) {
+ // get EOF indicator, see whether it is NUL (ok)
+ // (and don't trash s[0]!)
+ if (safe_read(STDIN_FILENO, &s[1], 1) != 1 || s[1] != 0) {
// don't send error msg to peer - it obviously
- // don't follow the protocol, so probably
+ // doesn't follow the protocol, so probably
// it can't understand us either
goto err_exit;
}
// chmod completely downloaded file as "readable+writable"
fchmod(fd, 0600);
// accumulate dump state
- // N.B. after all files are dumped spooling should be 1+2+3==6
- spooling += s[0];
+ // N.B. after all files are dumped spooling should be 1+2+4==7
+ spooling |= (1 << (s[0]-1)); // bit 1: ctrlfile; bit 2: datafile
}
+
free(s);
close(fd); // NB: can do close(-1). Who cares?
- // spawn spool helper and exit if all files are dumped
- if (6 == spooling && *argv) {
- // signal OK
- safe_write(STDOUT_FILENO, "", 1);
- // does not return (exits 0)
- exec_helper(filenames, argv);
- }
+ // NB: don't do "signal OK" write here, it will be done
+ // at the top of the loop
} // while (1)
err_exit:
// don't keep corrupted files
if (spooling) {
- if (filenames[0])
- unlink(filenames[0]);
- if (filenames[1])
- unlink(filenames[1]);
+#define i spooling
+ for (i = 2; --i >= 0; )
+ if (filenames[i])
+ unlink(filenames[i]);
}
return EXIT_FAILURE;
}
projects / oweals / busybox.git / blobdiff