Upgrade netcat a lot. Make -e able to take the rest of the command line as

what to exec.  Add -f mode and a brief explanation of how to use it to replace
minicom.  Add -l -l mode so you can turn any command into a server.  And group
all of netcat's command line options under two CONFIG entries, so if you
disable both it doesn't use getopt at all.


git-svn-id: svn://busybox.net/trunk/busybox@15675 69ca8d6d-28ef-0310-b511-8ec308f3f277

4 files changed, 145 insertions, 116 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 6d6213901..af45511d4 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -19,6 +19,7 @@
 #include <fcntl.h>
 #include <inttypes.h>
 #include <netdb.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
diff --git a/include/usage.h b/include/usage.h
index 3c1fb18e9..7c63e2f85 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -2105,23 +2105,41 @@ USE_FEATURE_MDEV_CONFIG( \
         " or\n" \
         "$ nameif -c /etc/my_mactab_file\n" \
 
-#ifdef CONFIG_NC_GAPING_SECURITY_HOLE
-#  define USAGE_NC_EXEC(a) a
+#if ENABLE_NC_SERVER || ENABLE_NC_EXTRA
+#define NC_BR1 "["
+#define NC_BR2 "]"
 #else
-#  define USAGE_NC_EXEC(a)
+#define NC_BR1
+#define NC_BR2
 #endif
+
 #define nc_trivial_usage \
-        "[OPTIONS] [IP] [port]"
+        "[" \
+        NC_BR1 USE_NC_SERVER("-lp")USE_NC_EXTRA("iwf") NC_BR2 \
+        " ["USE_NC_EXTRA("FILENAME|")"{IPADDR PORTNUM}]"USE_NC_EXTRA(" [-e COMMAND]")
 #define nc_full_usage \
-        "Netcat opens a pipe to IP:port\n\n" \
-        "Options:\n" \
-        "\t-l\t\tlisten mode, for inbound connects\n" \
-        "\t-p PORT\t\tlocal port number\n" \
-        "\t-i SECS\t\tdelay interval for lines sent\n" \
-        USAGE_NC_EXEC( \
-        "\t-e PROG\t\tprogram to exec after connect (dangerous!)\n" \
+        "Netcat opens a pipe, either to IP:port\n\n" \
+        "Options:" \
+        USE_NC_EXTRA( \
+                "\n\t-e\t\texec rest of command line after connect\n" \
+                "\t-i SECS\t\tdelay interval for lines sent\n" \
+                "\t-w SECS\t\ttimeout for connect\n" \
+                "\t-f filename\tuse file (ala /dev/ttyS0) instead of network" \
         ) \
-        "\t-w SECS\t\ttimeout for connects and final net reads"
+        USE_NC_SERVER( \
+                "\n\t-l\t\tlisten mode, for inbound connects\n" \
+                USE_NC_EXTRA("\t\t\t(use -l twice with -e for persistent server)\n") \
+                "\t-p PORT\t\tlocal port number" \
+        )
+
+
+#define nc_notes_usage "" \
+        USE_NC_EXTRA( \
+                "To use netcat as a terminal emulator on a serial port:\n\n" \
+                "$ stty 115200 -F /dev/ttyS0\n" \
+                "$ stty raw -echo -ctlecho && nc -f /dev/ttyS0\n" \
+        ) ""
+
 #define nc_example_usage \
         "$ nc foobar.somedomain.com 25\n" \
         "220 foobar ESMTP Exim 3.12 #1 Sat, 15 Apr 2000 00:03:02 -0600\n" \
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);
                         }
                 }
         }