source: npl/overig/netcat_openbsd/patches/0011-misc-failures-and-features.patch @ c5c522c

From: Aron Xu <aron@debian.org>
Date: Mon, 13 Feb 2012 19:06:52 +0800
Subject: misc connection failures

---
 nc.1     |   76 ++++++++++++++++++++++++++++++++++++---
 netcat.c |  119 ++++++++++++++++++++++++++++++++++++++++++--------------------
 2 files changed, 153 insertions(+), 42 deletions(-)

diff --git a/nc.1 b/nc.1
index 60e3668..477cb1b 100644
--- a/nc.1
+++ b/nc.1
@@ -34,7 +34,7 @@
 .Sh SYNOPSIS
 .Nm nc
 .Bk -words
-.Op Fl 46CDdhklnrStUuvZz
+.Op Fl 46bCDdhklnrStUuvZz
 .Op Fl I Ar length
 .Op Fl i Ar interval
 .Op Fl O Ar length
@@ -99,6 +99,8 @@ to use IPv4 addresses only.
 Forces
 .Nm
 to use IPv6 addresses only.
+.It Fl b
+Allow broadcast.
 .It Fl C
 Send CRLF as line-ending.
 .It Fl D
@@ -323,6 +325,54 @@ and which side is being used as a
 The connection may be terminated using an
 .Dv EOF
 .Pq Sq ^D .
+.Pp
+There is no
+.Fl c
+or
+.Fl e
+option in this netcat, but you still can execute a command after connection
+being established by redirecting file descriptors. Be cautious here because
+opening a port and let anyone connected execute arbitrary command on your
+site is DANGEROUS. If you really need to do this, here is an example:
+.Pp
+On
+.Sq server
+side:
+.Pp
+.Dl $ rm -f /tmp/f; mkfifo /tmp/f
+.Dl $ cat /tmp/f | /bin/sh -i 2>&1 | nc -l 127.0.0.1 1234 > /tmp/f
+.Pp
+On
+.Sq client
+side:
+.Pp
+.Dl $ nc host.example.com 1234
+.Dl $ (shell prompt from host.example.com)
+.Pp
+By doing this, you create a fifo at /tmp/f and make nc listen at port 1234
+of address 127.0.0.1 on
+.Sq server
+side, when a
+.Sq client
+establishes a connection successfully to that port, /bin/sh gets executed
+on
+.Sq server
+side and the shell prompt is given to
+.Sq client
+side.
+.Pp
+When connection is terminated,
+.Nm
+quits as well. Use
+.Fl k
+if you want it keep listening, but if the command quits this option won't
+restart it or keep
+.Nm
+running. Also don't forget to remove the file descriptor once you don't need
+it anymore:
+.Pp
+.Dl $ rm -f /tmp/f
+.Pp
 .Sh DATA TRANSFER
 The example in the previous section can be expanded to build a
 basic data transfer model.
@@ -382,15 +432,30 @@ The
 flag can be used to tell
 .Nm
 to report open ports,
-rather than initiate a connection.
+rather than initiate a connection. Usually it's useful to turn on verbose
+output to stderr by use this option in conjunction with
+.Fl v
+option.
+.Pp
 For example:
 .Bd -literal -offset indent
-$ nc -z host.example.com 20-30
+$ nc \-zv host.example.com 20-30
 Connection to host.example.com 22 port [tcp/ssh] succeeded!
 Connection to host.example.com 25 port [tcp/smtp] succeeded!
 .Ed
 .Pp
-The port range was specified to limit the search to ports 20 \- 30.
+The port range was specified to limit the search to ports 20 \- 30, and is
+scanned by increasing order.
+.Pp
+You can also specify a list of ports to scan, for example:
+.Bd -literal -offset indent
+$ nc \-zv host.example.com 80 20 22
+nc: connect to host.example.com 80 (tcp) failed: Connection refused
+nc: connect to host.example.com 20 (tcp) failed: Connection refused
+Connection to host.example.com port [tcp/ssh] succeeded!
+.Ed
+.Pp
+The ports are scanned by the order you given.
 .Pp
 Alternatively, it might be useful to know which server software
 is running, and which versions.
@@ -455,6 +520,9 @@ Original implementation by *Hobbit*
 .br
 Rewritten with IPv6 support by
 .An Eric Jackson Aq ericj@monkey.org .
+.br
+Modified for Debian port by Aron Xu
+.Aq aron@debian.org .
 .Sh CAVEATS
 UDP port scans using the
 .Fl uz
diff --git a/netcat.c b/netcat.c
index bf9940f..c938d11 100644
--- a/netcat.c
+++ b/netcat.c
@@ -88,6 +88,7 @@
 #include <netdb.h>
 #include <poll.h>
 #include <signal.h>
+#include <stddef.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -115,6 +116,7 @@
 #define UDP_SCAN_TIMEOUT 3                     /* Seconds */
 
 /* Command Line Options */
+int    bflag;                                  /* Allow Broadcast */
 int     Cflag = 0;                              /* CRLF line-ending */
 int    dflag;                                  /* detached, no stdin */
 unsigned int iflag;                            /* Interval Flag */
@@ -146,7 +148,7 @@ char *portlist[PORT_MAX+1];
 char *unix_dg_tmp_socket;
 
 void   atelnet(int, unsigned char *, unsigned int);
-void   build_ports(char *);
+void   build_ports(char **);
 void   help(void);
 int    local_listen(char *, char *, struct addrinfo);
 void   readwrite(int);
@@ -171,11 +173,14 @@ int
 main(int argc, char *argv[])
 {
        int ch, s, ret, socksv;
-       char *host, *uport;
+       char *host, **uport;
        struct addrinfo hints;
        struct servent *sv;
        socklen_t len;
-       struct sockaddr_storage cliaddr;
+       union {
+               struct sockaddr_storage storage;
+               struct sockaddr_un forunix;
+       } cliaddr;
        char *proxy = NULL;
        const char *errstr, *proxyhost = "", *proxyport = NULL;
        struct addrinfo proxyhints;
@@ -189,7 +194,7 @@ main(int argc, char *argv[])
        sv = NULL;
 
        while ((ch = getopt(argc, argv,
-           "46CDdhI:i:jklnO:P:p:q:rSs:tT:UuV:vw:X:x:Zz")) != -1) {
+           "46bCDdhI:i:jklnO:P:p:q:rSs:tT:UuV:vw:X:x:Zz")) != -1) {
                switch (ch) {
                case '4':
                        family = AF_INET;
@@ -197,6 +202,13 @@ main(int argc, char *argv[])
                case '6':
                        family = AF_INET6;
                        break;
+               case 'b':
+# if defined(SO_BROADCAST)
+                       bflag = 1;
+# else
+                       errx(1, "no broadcast frame support available");
+# endif
+                       break;
                case 'U':
                        family = AF_UNIX;
                        break;
@@ -342,35 +354,40 @@ main(int argc, char *argv[])
 
        /* Cruft to make sure options are clean, and used properly. */
        if (argv[0] && !argv[1] && family == AF_UNIX) {
-               if (uflag)
-                       errx(1, "cannot use -u and -U");
 # if defined(IPPROTO_DCCP) && defined(SOCK_DCCP)
                if (dccpflag)
                        errx(1, "cannot use -Z and -U");
 # endif
                host = argv[0];
                uport = NULL;
-       } else if (!argv[0] && lflag) {
-               if (sflag)
-                       errx(1, "cannot use -s and -l");
-               if (zflag)
-                       errx(1, "cannot use -z and -l");
-               if (pflag)
-                       uport=pflag;
-       } else if (!lflag && kflag) {
-               errx(1, "cannot use -k without -l");
-       } else if (argv[0] && !argv[1]) {
-               if  (!lflag)
-                       usage(1);
-               uport = argv[0];
+       } else if (argv[0] && !argv[1] && lflag) {
+               if (pflag) {
+                       uport = &pflag;
+                       host = argv[0];
+               } else {
+                       uport = argv;
+                       host = NULL;
+               }
+       } else if (!argv[0] && lflag && pflag) {
+               uport = &pflag;
                host = NULL;
        } else if (argv[0] && argv[1]) {
                host = argv[0];
-               uport = argv[1];
+               uport = &argv[1];
        } else
                usage(1);
 
-
+       if (lflag) {
+               if (sflag)
+                       errx(1, "cannot use -s and -l");
+               if (zflag)
+                       errx(1, "cannot use -z and -l");
+               if (pflag)
+                       /* This still does not work well because of getopt mess
+                       errx(1, "cannot use -p and -l"); */
+                       uport = &pflag;
+       } else if (!lflag && kflag)
+               errx(1, "cannot use -k without -l");
 
        /* Get name of temporary socket for unix datagram client */
        if ((family == AF_UNIX) && uflag && !lflag) {
@@ -448,7 +465,7 @@ main(int argc, char *argv[])
                        else
                                s = unix_listen(host);
                } else
-                       s = local_listen(host, uport, hints);
+                       s = local_listen(host, *uport, hints);
                if (s < 0)
                        err(1, NULL);
 
@@ -457,7 +474,8 @@ main(int argc, char *argv[])
                        local = ":::";
                else
                        local = "0.0.0.0";
-               fprintf(stderr, "Listening on [%s] (family %d, port %d)\n",
+               if (vflag && (family != AF_UNIX))
+               fprintf(stderr, "Listening on [%s] (family %d, port %s)\n",
                        host ?: local,
                        family,
                        *uport);
@@ -490,13 +508,17 @@ main(int argc, char *argv[])
                                len = sizeof(cliaddr);
                                connfd = accept(s, (struct sockaddr *)&cliaddr,
                                    &len);
-                               if(vflag) {
+                               if(vflag && family == AF_UNIX) {
+                                       fprintf(stderr, "Connection from \"%.*s\" accepted\n",
+                                               (len - (int)offsetof(struct sockaddr_un, sun_path)),
+                                               ((struct sockaddr_un*)&cliaddr)->sun_path);
+                               } else if(vflag) {
                                        char *proto = proto_name(uflag, dccpflag);
                                /* Don't look up port if -n. */
                                        if (nflag)
                                                sv = NULL;
                                        else
-                                               sv = getservbyport(ntohs(atoi(uport)),
+                                               sv = getservbyport(ntohs(atoi(*uport)),
                                                        proto);
 
                                        if (((struct sockaddr *)&cliaddr)->sa_family == AF_INET) {
@@ -504,7 +526,7 @@ main(int argc, char *argv[])
                                                inet_ntop(((struct sockaddr *)&cliaddr)->sa_family,&(((struct sockaddr_in *)&cliaddr)->sin_addr),dst,INET_ADDRSTRLEN);
                                                fprintf(stderr, "Connection from [%s] port %s [%s/%s] accepted (family %d, sport %d)\n",
                                                        dst,
-                                                       uport,
+                                                       *uport,
                                                        proto,
                                                        sv ? sv->s_name : "*",
                                                        ((struct sockaddr *)(&cliaddr))->sa_family,
@@ -515,7 +537,7 @@ main(int argc, char *argv[])
                                                inet_ntop(((struct sockaddr *)&cliaddr)->sa_family,&(((struct sockaddr_in6 *)&cliaddr)->sin6_addr),dst,INET6_ADDRSTRLEN);
                                                fprintf(stderr, "Connection from [%s] port %s [%s/%s] accepted (family %d, sport %d)\n",
                                                        dst,
-                                                       uport,
+                                                       *uport,
                                                        proto,
                                                        sv ? sv->s_name : "*",
                                                        ((struct sockaddr *)&cliaddr)->sa_family,
@@ -523,17 +545,21 @@ main(int argc, char *argv[])
                                        }
                                        else {
                                                fprintf(stderr, "Connection from unknown port %s [%s/%s] accepted (family %d, sport %d)\n",
-                                                       uport,
+                                                       *uport,
                                                        proto,
                                                        sv ? sv->s_name : "*",
                                                        ((struct sockaddr *)(&cliaddr))->sa_family,
                                                        ntohs(((struct sockaddr_in *)&cliaddr)->sin_port));
                                        }
                                }
+                                if(!kflag)
+                                        close(s);
                                readwrite(connfd);
                                close(connfd);
                        }
 
+                       if (vflag && kflag)
+                                fprintf(stderr, "Connection closed, listening again.\n");
                        if (kflag)
                                continue;
                        if (family != AF_UNIX) {
@@ -641,6 +667,8 @@ unix_bind(char *path)
                return (-1);
        }
 
+        unlink(path);
+
        if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
                close(s);
                return (-1);
@@ -662,8 +690,10 @@ unix_connect(char *path)
                if ((s = unix_bind(unix_dg_tmp_socket)) < 0)
                        return (-1);
        } else {
-               if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
+               if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
+                        errx(1,"create unix socket failed");
                        return (-1);
+                }
        }
        (void)fcntl(s, F_SETFD, 1);
 
@@ -674,9 +704,11 @@ unix_connect(char *path)
            sizeof(sun.sun_path)) {
                close(s);
                errno = ENAMETOOLONG;
+                warn("unix connect abandoned");
                return (-1);
        }
        if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
+                warn("unix connect failed");
                close(s);
                return (-1);
        }
@@ -1105,22 +1137,23 @@ atelnet(int nfd, unsigned char *buf, unsigned int size)
  * that we should try to connect to.
  */
 void
-build_ports(char *p)
+build_ports(char **p)
 {
         struct servent *sv;
        const char *errstr;
        char *n;
        int hi, lo, cp;
        int x = 0;
+       int i;
 
        char *proto = proto_name(uflag, dccpflag);
-       sv = getservbyname(p, proto);
+       sv = getservbyname(*p, proto);
         if (sv) {
                 portlist[0] = calloc(1, PORT_MAX_LEN);
                 if (portlist[0] == NULL)
                         err(1, NULL);
                 snprintf(portlist[0], PORT_MAX_LEN, "%d", ntohs(sv->s_port));
-        } else if ((n = strchr(p, '-')) != NULL) {
+        } else if ((n = strchr(*p, '-')) != NULL) {
                *n = '\0';
                n++;
 
@@ -1128,9 +1161,9 @@ build_ports(char *p)
                hi = strtonum(n, 1, PORT_MAX, &errstr);
                if (errstr)
                        errx(1, "port number %s: %s", errstr, n);
-               lo = strtonum(p, 1, PORT_MAX, &errstr);
+               lo = strtonum(*p, 1, PORT_MAX, &errstr);
                if (errstr)
-                       errx(1, "port number %s: %s", errstr, p);
+                       errx(1, "port number %s: %s", errstr, *p);
 
                if (lo > hi) {
                        cp = hi;
@@ -1160,10 +1193,12 @@ build_ports(char *p)
                        }
                }
        } else {
-               hi = strtonum(p, 1, PORT_MAX, &errstr);
+               hi = strtonum(*p, 1, PORT_MAX, &errstr);
                if (errstr)
-                       errx(1, "port number %s: %s", errstr, p);
-               portlist[0] = strdup(p);
+                       errx(1, "port number %s: %s", errstr, *p);
+               for (i=0;p[i];i++) {
+                       portlist[i] = strdup(p[i]);
+               }
                if (portlist[0] == NULL)
                        err(1, NULL);
        }
@@ -1198,6 +1233,13 @@ set_common_sockopts(int s)
 {
        int x = 1;
 
+# if defined(SO_BROADCAST)
+       if (bflag) {
+               if (setsockopt(s, IPPROTO_TCP, SO_BROADCAST,
+                       &x, sizeof(x)) == -1)
+                       err(1, NULL);
+       }
+# endif
 # if defined(TCP_MD5SIG)
        if (Sflag) {
                if (setsockopt(s, IPPROTO_TCP, TCP_MD5SIG,
@@ -1293,6 +1335,7 @@ help(void)
        fprintf(stderr, "\tCommand Summary:\n\
        \t-4            Use IPv4\n\
        \t-6            Use IPv6\n\
+       \t-b            Allow broadcast\n\
        \t-C            Send CRLF as line-ending\n\
        \t-D            Enable the debug socket option\n\
        \t-d            Detach from stdin\n\
@@ -1329,7 +1372,7 @@ void
 usage(int ret)
 {
        fprintf(stderr,
-           "usage: nc [-46CDdhjklnrStUuvZz] [-I length] [-i interval] [-O length]\n"
+           "usage: nc [-46bCDdhjklnrStUuvZz] [-I length] [-i interval] [-O length]\n"
            "\t  [-P proxy_username] [-p source_port] [-q seconds] [-s source]\n"
            "\t  [-T toskeyword] [-V rtable] [-w timeout] [-X proxy_protocol]\n"
            "\t  [-x proxy_address[:port]] [destination] [port]\n");
--