1 /* netcat.c - Forward stdin/stdout to a file or network connection.
2 *
3 * Copyright 2007 Rob Landley <rob@landley.net>
4 *
5 * TODO: genericize for telnet/microcom/tail-f, fix -t
6
7 USE_NETCAT(NEWTOY(netcat, "^tElLw#<1W#<1p#<1>65535q#<1s:f:46uUn[!tlL][!Lw][!Lu][!46U]", TOYFLAG_BIN))
8 USE_NETCAT(OLDTOY(nc, netcat, TOYFLAG_USR|TOYFLAG_BIN))
9
10 config NETCAT
11 bool "netcat"
12 default y
13 help
14 usage: netcat [-46ElLtUu] [-wpq #] [-s addr] {IPADDR PORTNUM|-f FILENAME|COMMAND...}
15
16 Forward stdin/stdout to a file or network connection.
17
18 -4 Force IPv4
19 -6 Force IPv6
20 -E Forward stderr
21 -f Use FILENAME (ala /dev/ttyS0) instead of network
22 -l Listen for one incoming connection, then exit
23 -L Listen and background each incoming connection (server mode)
24 -n No DNS lookup
25 -p Local port number
26 -q Quit SECONDS after EOF on stdin, even if stdout hasn't closed yet
27 -s Local source address
28 -t Allocate tty
29 -u Use UDP
30 -U Use a UNIX domain socket
31 -w SECONDS timeout to establish connection
32 -W SECONDS timeout for more data on an idle connection
33
34 When listening the COMMAND line is executed as a child process to handle
35 an incoming connection. With no COMMAND -l forwards the connection
36 to stdin/stdout. If no -p specified, -l prints the port it bound to and
37 backgrounds itself (returning immediately).
38
39 For a quick-and-dirty server, try something like:
40 netcat -s 127.0.0.1 -p 1234 -tL sh -l
41
42 Or use "stty 115200 -F /dev/ttyS0 && stty raw -echo -ctlecho" with
43 netcat -f to connect to a serial port.
44 */
45
46 #define FOR_netcat
47 #include "toys.h"
48
49 GLOBALS(
50 char *f, *s;
51 long q, p, W, w;
52 )
53
timeout(int signum)54 static void timeout(int signum)
55 {
56 if (TT.w) error_exit("Timeout");
57 xexit();
58 }
59
60 // open AF_UNIX socket
usock(char * name,int type,int out)61 static int usock(char *name, int type, int out)
62 {
63 int sockfd;
64 struct sockaddr_un sockaddr;
65
66 memset(&sockaddr, 0, sizeof(struct sockaddr_un));
67
68 if (strlen(name) + 1 > sizeof(sockaddr.sun_path))
69 error_exit("socket path too long %s", name);
70 strcpy(sockaddr.sun_path, name);
71 sockaddr.sun_family = AF_UNIX;
72
73 sockfd = xsocket(AF_UNIX, type, 0);
74 (out?xconnect:xbind)(sockfd, (struct sockaddr*)&sockaddr, sizeof(sockaddr));
75
76 return sockfd;
77 }
78
netcat_main(void)79 void netcat_main(void)
80 {
81 #ifdef TOYBOX_OH_ADAPT
82 /* Remove unsupported -f and -t option */
83 if (toys.optflags & FLAG_t) error_exit("Unknown option 't'");
84 if (toys.optflags & FLAG_f) error_exit("Unknown option 'f'");
85 #endif
86
87 int sockfd = -1, in1 = 0, in2 = 0, out1 = 1, out2 = 1, family = AF_UNSPEC,
88 type = FLAG(u) ? SOCK_DGRAM : SOCK_STREAM;
89 socklen_t len;
90 pid_t child;
91
92 // Addjust idle and quit_delay to ms or -1 for no timeout
93 TT.W = TT.W ? TT.W*1000 : -1;
94 TT.q = TT.q ? TT.q*1000 : -1;
95
96 xsignal(SIGCHLD, SIG_IGN);
97 if (TT.w) {
98 xsignal(SIGALRM, timeout);
99 alarm(TT.w);
100 }
101
102 // The argument parsing logic can't make "<2" conditional on other
103 // arguments like -f and -l, so do it by hand here.
104 if (FLAG(f) ? toys.optc : (!FLAG(l) && !FLAG(L) && toys.optc!=2-FLAG(U)))
105 help_exit("bad argument count");
106
107 if (FLAG(4)) family = AF_INET;
108 else if (FLAG(6)) family = AF_INET6;
109 else if (FLAG(U)) family = AF_UNIX;
110
111 if (TT.f) in1 = out2 = xopen(TT.f, O_RDWR);
112 else {
113 // Setup socket
114 if (!FLAG(l) && !FLAG(L)) {
115 if (FLAG(U)) sockfd = usock(toys.optargs[0], type, 1);
116 else sockfd = xconnectany(xgetaddrinfo(toys.optargs[0],
117 toys.optargs[1], family, type, 0, AI_NUMERICHOST*FLAG(n)));
118
119 // We have a connection. Disarm timeout and start poll/send loop.
120 alarm(0);
121 in1 = out2 = sockfd;
122 pollinate(in1, in2, out1, out2, TT.W, TT.q);
123 } else {
124 // Listen for incoming connections
125 if (FLAG(U)) {
126 if (!FLAG(s)) error_exit("-s must be provided if using -U with -L/-l");
127 sockfd = usock(TT.s, type, 0);
128 } else {
129 sprintf(toybuf, "%ld", TT.p);
130 sockfd = xbindany(xgetaddrinfo(TT.s, toybuf, family, type, 0, 0));
131 }
132
133 if (!FLAG(u) && listen(sockfd, 5)) perror_exit("listen");
134 if (!TT.p && !FLAG(U)) {
135 struct sockaddr* address = (void*)toybuf;
136 short port_be;
137
138 len = sizeof(struct sockaddr_storage);
139 getsockname(sockfd, address, &len);
140 if (address->sa_family == AF_INET)
141 port_be = ((struct sockaddr_in*)address)->sin_port;
142 else if (address->sa_family == AF_INET6)
143 port_be = ((struct sockaddr_in6*)address)->sin6_port;
144 else perror_exit("getsockname: bad family");
145
146 dprintf(1, "%d\n", SWAP_BE16(port_be));
147 // Return immediately if no -p and -Ll has arguments, so wrapper
148 // script can use port number.
149 if (CFG_TOYBOX_FORK && toys.optc && xfork()) goto cleanup;
150 }
151
152 do {
153 len = sizeof(struct sockaddr_storage);
154 if (FLAG(u)) {
155 if (-1 == recvfrom(in1 = dup(sockfd), &child, 1, MSG_PEEK,
156 (void *)toybuf, &len)) perror_exit("recvfrom");
157 } else if ((in1 = accept(sockfd, 0, 0))<0) perror_exit("accept");
158 out2 = in1;
159 child = 0;
160
161 // We have a connection. Disarm timeout.
162 alarm(0);
163
164 // Fork a child as necessary. Parent cleans up and continues here.
165 if (toys.optc && FLAG(L)) NOEXIT(child = XVFORK());
166 if (child) {
167 close(in1);
168 continue;
169 }
170
171 if (FLAG(u))
172 xconnect(in1, (void *)toybuf, sizeof(struct sockaddr_storage));
173
174 // Cleanup and redirect for exec
175 if (toys.optc) {
176 // Do we need a tty?
177 // TODO nommu and -t only affects server mode...
178 // if (FLAG(t)) child = forkpty(&fdout, NULL, NULL, NULL);
179
180 close(sockfd);
181 dup2(in1, 0);
182 dup2(in1, 1);
183 if (FLAG(E)) dup2(in1, 2);
184 if (in1>2) close(in1);
185 xexec(toys.optargs);
186
187 // Copy stdin/out
188 } else {
189 pollinate(in1, in2, out1, out2, TT.W, TT.q);
190 close(in1);
191 }
192 } while (FLAG(L));
193 }
194 }
195
196 cleanup:
197 if (CFG_TOYBOX_FREE) {
198 close(in1);
199 close(sockfd);
200 }
201 }