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-rw-r--r--networking/Config.in16
-rw-r--r--networking/nc.c202
2 files changed, 114 insertions, 104 deletions
diff --git a/networking/Config.in b/networking/Config.in
index e95ae0d74..e5eb11caa 100644
--- a/networking/Config.in
+++ b/networking/Config.in
@@ -446,13 +446,21 @@ config CONFIG_NC
A simple Unix utility which reads and writes data across network
connections.
-config CONFIG_NC_GAPING_SECURITY_HOLE
- bool "gaping security hole"
+config CONFIG_NC_SERVER
+ bool "Netcat server options (-lp)"
default n
depends on CONFIG_NC
help
- Add support for executing a program after making or receiving a
- successful connection (-e option).
+ Allow netcat to act as a server.
+
+config CONFIG_NC_EXTRA
+ bool "Netcat extensions (-eiw and filename)"
+ default n
+ depends on CONFIG_NC
+ help
+ Add -e (support for executing the rest of the command line after
+ making or receiving a successful connection), -i (delay interval for
+ lines sent), -w (timeout for initial connection).
config CONFIG_NETSTAT
bool "netstat"
diff --git a/networking/nc.c b/networking/nc.c
index 24f1aa5a5..bda0c407b 100644
--- a/networking/nc.c
+++ b/networking/nc.c
@@ -1,32 +1,16 @@
/* vi: set sw=4 ts=4: */
/* nc: mini-netcat - built from the ground up for LRP
- Copyright (C) 1998 Charles P. Wright
-
- 0.0.1 6K It works.
- 0.0.2 5K Smaller and you can also check the exit condition if you wish.
- 0.0.3 Uses select()
-
- 19980918 Busy Boxed! Dave Cinege
- 19990512 Uses Select. Charles P. Wright
- 19990513 Fixes stdin stupidity and uses buffers. Charles P. Wright
-
- Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
-*/
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <signal.h>
-
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <netinet/in.h>
-#include <arpa/inet.h>
-#include <netdb.h>
-#include <sys/ioctl.h>
+ *
+ * Copyright (C) 1998, 1999 Charles P. Wright
+ * Copyright (C) 1998 Dave Cinege
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+
#include "busybox.h"
+#define xread bb_xread
+
static void timeout(int signum)
{
bb_error_msg_and_die("Timed out");
@@ -34,79 +18,87 @@ static void timeout(int signum)
int nc_main(int argc, char **argv)
{
- int do_listen = 0, lport = 0, delay = 0, wsecs = 0, tmpfd, opt, sfd, x;
-
-#ifdef CONFIG_NC_GAPING_SECURITY_HOLE
- char *pr00gie = NULL;
-#endif
-
+ int do_listen = 0, lport = 0, delay = 0, wsecs = 0, execflag = 0, opt,
+ sfd = 0, cfd;
struct sockaddr_in address;
struct hostent *hostinfo;
-
fd_set readfds, testfds;
+ char *infile = NULL;
- while ((opt = getopt(argc, argv, "lp:i:e:w:")) > 0) {
- switch (opt) {
- case 'l':
- do_listen++;
- break;
- case 'p':
+ memset(&address, 0, sizeof(address));
+
+ if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) {
+ while ((opt = getopt(argc, argv, "lp:" USE_NC_EXTRA("i:ew:f:"))) > 0) {
+ if (ENABLE_NC_SERVER && opt=='l') do_listen++;
+ else if (ENABLE_NC_SERVER && opt=='p')
lport = bb_lookup_port(optarg, "tcp", 0);
+ else if (ENABLE_NC_EXTRA && opt=='w') wsecs = atoi(optarg);
+ else if (ENABLE_NC_EXTRA && opt=='i') delay = atoi(optarg);
+ else if (ENABLE_NC_EXTRA && opt=='f') infile = optarg;
+ else if (ENABLE_NC_EXTRA && opt=='e' && optind!=argc) {
+ execflag++;
break;
- case 'i':
- delay = atoi(optarg);
- break;
-#ifdef CONFIG_NC_GAPING_SECURITY_HOLE
- case 'e':
- pr00gie = optarg;
- break;
-#endif
- case 'w':
- wsecs = atoi(optarg);
- break;
- default:
- bb_show_usage();
+ } else bb_show_usage();
}
}
- if ((do_listen && optind != argc) || (!do_listen && optind + 2 != argc))
- bb_show_usage();
+
+ // For listen or file we need zero arguments, dialout is 2.
+ // For exec we need at least one more argument at the end, more ok
- sfd = bb_xsocket(AF_INET, SOCK_STREAM, 0);
- x = 1;
- if (setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &x, sizeof (x)) == -1)
- bb_perror_msg_and_die("reuseaddr");
- address.sin_family = AF_INET;
+ opt = (do_listen || infile) ? 0 : 2 + execflag;
+ if (execflag ? argc-optind < opt : argc-optind!=opt ||
+ (infile && do_listen))
+ bb_show_usage();
if (wsecs) {
signal(SIGALRM, timeout);
alarm(wsecs);
}
+
+ if (infile) cfd = bb_xopen(infile, O_RDWR);
+ else {
+ opt = 1;
+ sfd = bb_xsocket(AF_INET, SOCK_STREAM, 0);
+ fcntl(sfd, F_SETFD, FD_CLOEXEC);
+ setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof (opt));
+ address.sin_family = AF_INET;
- if (lport != 0) {
- memset(&address.sin_addr, 0, sizeof(address.sin_addr));
- address.sin_port = lport;
+ // Set local port.
- bb_xbind(sfd, (struct sockaddr *) &address, sizeof(address));
- }
+ if (lport != 0) {
+ address.sin_port = lport;
+
+ bb_xbind(sfd, (struct sockaddr *) &address, sizeof(address));
+ }
+
+ if (do_listen) {
+ socklen_t addrlen = sizeof(address);
+
+ bb_xlisten(sfd, do_listen);
- if (do_listen) {
- socklen_t addrlen = sizeof(address);
+ // If we didn't specify a port number, query and print it to stderr.
- bb_xlisten(sfd, 1);
- if ((tmpfd = accept(sfd, (struct sockaddr *) &address, &addrlen)) < 0)
- bb_perror_msg_and_die("accept");
+ if (!lport) {
+ socklen_t len = sizeof(address);
+ getsockname(sfd, &address, &len);
+ fdprintf(2, "%d\n", SWAP_BE16(address.sin_port));
+ }
+repeatyness:
+ if ((cfd = accept(sfd, (struct sockaddr *) &address, &addrlen)) < 0)
+ bb_perror_msg_and_die("accept");
- close(sfd);
- sfd = tmpfd;
- } else {
- hostinfo = xgethostbyname(argv[optind]);
+ if (!execflag) close(sfd);
+ } else {
+ hostinfo = xgethostbyname(argv[optind]);
- address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
- address.sin_port = bb_lookup_port(argv[optind+1], "tcp", 0);
+ address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
+ address.sin_port = bb_lookup_port(argv[optind+1], "tcp", 0);
- if (connect(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
- bb_perror_msg_and_die("connect");
+ if (connect(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
+ bb_perror_msg_and_die("connect");
+ cfd = sfd;
+ }
}
if (wsecs) {
@@ -114,24 +106,40 @@ int nc_main(int argc, char **argv)
signal(SIGALRM, SIG_DFL);
}
-#ifdef CONFIG_NC_GAPING_SECURITY_HOLE
/* -e given? */
- if (pr00gie) {
- dup2(sfd, 0);
- close(sfd);
+ if (execflag) {
+ if(cfd) {
+ signal(SIGCHLD, SIG_IGN);
+ dup2(cfd, 0);
+ close(cfd);
+ }
dup2(0, 1);
dup2(0, 2);
- execl(pr00gie, pr00gie, NULL);
+
+ // With more than one -l, repeatedly act as server.
+
+ if (do_listen>1 && vfork()) {
+ // This is a bit weird as cleanup goes, since we wind up with no
+ // stdin/stdout/stderr. But it's small and shouldn't hurt anything.
+ // We check for cfd == 0 above.
+ close(0);
+ close(1);
+ close(2);
+
+ goto repeatyness;
+ }
+ execvp(argv[optind], argv+optind);
/* Don't print stuff or it will go over the wire.... */
- _exit(-1);
+ _exit(127);
}
-#endif /* CONFIG_NC_GAPING_SECURITY_HOLE */
+ // Select loop copying stdin to cfd, and cfd to stdout.
+
FD_ZERO(&readfds);
- FD_SET(sfd, &readfds);
+ FD_SET(cfd, &readfds);
FD_SET(STDIN_FILENO, &readfds);
- while (1) {
+ for (;;) {
int fd;
int ofd;
int nread;
@@ -143,30 +151,24 @@ int nc_main(int argc, char **argv)
for (fd = 0; fd < FD_SETSIZE; fd++) {
if (FD_ISSET(fd, &testfds)) {
- if ((nread = safe_read(fd, bb_common_bufsiz1,
- sizeof(bb_common_bufsiz1))) < 0)
- {
- bb_perror_msg_and_die(bb_msg_read_error);
- }
+ nread = xread(fd, bb_common_bufsiz1, sizeof(bb_common_bufsiz1));
- if (fd == sfd) {
- if (nread == 0)
- exit(0);
+ if (fd == cfd) {
+ if (!nread) exit(0);
ofd = STDOUT_FILENO;
} else {
- if (nread <= 0) {
- shutdown(sfd, 1 /* send */ );
- close(STDIN_FILENO);
+ if (!nread) {
+ // Close outgoing half-connection so they get EOF, but
+ // leave incoming alone so we can see response.
+ shutdown(cfd, 1);
FD_CLR(STDIN_FILENO, &readfds);
}
- ofd = sfd;
+ ofd = cfd;
}
if (bb_full_write(ofd, bb_common_bufsiz1, nread) < 0)
bb_perror_msg_and_die(bb_msg_write_error);
- if (delay > 0) {
- sleep(delay);
- }
+ if (delay > 0) sleep(delay);
}
}
}
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