/* netcat.c - Forward stdin/stdout to a file or network connection. * * Copyright 2007 Rob Landley * * TODO: udp, ipv6, genericize for telnet/microcom/tail-f * fix -t, xconnect * netcat -L zombies USE_NETCAT(OLDTOY(nc, netcat, TOYFLAG_USR|TOYFLAG_BIN)) USE_NETCAT(NEWTOY(netcat, USE_NETCAT_LISTEN("^tlL")"w#<1W#<1p#<1>65535q#<1s:f:46uU"USE_NETCAT_LISTEN("[!tlL][!Lw]")"[!46U]", TOYFLAG_BIN)) config NETCAT bool "netcat" default y help usage: netcat [-46U] [-u] [-wpq #] [-s addr] {IPADDR PORTNUM|-f FILENAME} Forward stdin/stdout to a file or network connection. -4 Force IPv4 -6 Force IPv6 -f Use FILENAME (ala /dev/ttyS0) instead of network -p Local port number -q Quit SECONDS after EOF on stdin, even if stdout hasn't closed yet -s Local source address -u Use UDP -U Use a UNIX domain socket -w SECONDS timeout to establish connection -W SECONDS timeout for more data on an idle connection Use "stty 115200 -F /dev/ttyS0 && stty raw -echo -ctlecho" with netcat -f to connect to a serial port. config NETCAT_LISTEN bool "netcat server options (-let)" default y depends on NETCAT help usage: netcat [-t] [-lL COMMAND...] -l Listen for one incoming connection -L Listen for multiple incoming connections (server mode) -t Allocate tty (must come before -l or -L) The command line after -l or -L is executed (as a child process) to handle each incoming connection. If blank -l waits for a connection and forwards it to stdin/stdout. If no -p specified, -l prints port it bound to and backgrounds itself (returning immediately). For a quick-and-dirty server, try something like: netcat -s 127.0.0.1 -p 1234 -tL /bin/bash -l */ #define FOR_netcat #include "toys.h" GLOBALS( char *f, *s; long q, p, W, w; ) static void timeout(int signum) { if (TT.w) error_exit("Timeout"); xexit(); } static void set_alarm(int seconds) { xsignal(SIGALRM, seconds ? timeout : SIG_DFL); alarm(seconds); } // open AF_UNIX socket static int usock(char *name, int type, int out) { int sockfd; struct sockaddr_un sockaddr; memset(&sockaddr, 0, sizeof(struct sockaddr_un)); if (strlen(name) + 1 > sizeof(sockaddr.sun_path)) error_exit("socket path too long %s", name); strcpy(sockaddr.sun_path, name); sockaddr.sun_family = AF_UNIX; sockfd = xsocket(AF_UNIX, type, 0); (out?xconnect:xbind)(sockfd, (struct sockaddr*)&sockaddr, sizeof(sockaddr)); return sockfd; } void netcat_main(void) { int sockfd = -1, in1 = 0, in2 = 0, out1 = 1, out2 = 1, family = AF_UNSPEC, ll = FLAG(L)|FLAG(l), type = FLAG(u) ? SOCK_DGRAM : SOCK_STREAM; pid_t child; // Addjust idle and quit_delay to ms or -1 for no timeout TT.W = TT.W ? TT.W*1000 : -1; TT.q = TT.q ? TT.q*1000 : -1; set_alarm(TT.w); // The argument parsing logic can't make "<2" conditional on other // arguments like -f and -l, so do it by hand here. if (FLAG(f) ? toys.optc : (!ll && toys.optc!=(FLAG(U)?1:2))) help_exit("bad argument count"); if (FLAG(4)) family = AF_INET; else if (FLAG(6)) family = AF_INET6; else if (FLAG(U)) family = AF_UNIX; if (TT.f) in1 = out2 = xopen(TT.f, O_RDWR); else { // Setup socket if (!ll) { if (FLAG(U)) sockfd = usock(toys.optargs[0], type, 1); else sockfd = xconnectany(xgetaddrinfo(toys.optargs[0], toys.optargs[1], family, type, 0, 0)); // We have a connection. Disarm timeout and start poll/send loop. set_alarm(0); in1 = out2 = sockfd; pollinate(in1, in2, out1, out2, TT.W, TT.q); } else { // Listen for incoming connections if (FLAG(U)) { if (!FLAG(s)) error_exit("-s must be provided if using -U with -L/-l"); sockfd = usock(TT.s, type, 0); } else { sprintf(toybuf, "%ld", TT.p); sockfd = xbindany(xgetaddrinfo(TT.s, toybuf, family, type, 0, 0)); } if (listen(sockfd, 5)) error_exit("listen"); if (!TT.p && !FLAG(U)) { struct sockaddr* address = (void*)toybuf; socklen_t len = sizeof(struct sockaddr_storage); short port_be; getsockname(sockfd, address, &len); if (address->sa_family == AF_INET) port_be = ((struct sockaddr_in*)address)->sin_port; else if (address->sa_family == AF_INET6) port_be = ((struct sockaddr_in6*)address)->sin6_port; else perror_exit("getsockname: bad family"); dprintf(1, "%d\n", SWAP_BE16(port_be)); // Return immediately if no -p and -Ll has arguments, so wrapper // script can use port number. if (CFG_TOYBOX_FORK && toys.optc && xfork()) goto cleanup; } do { child = 0; in1 = out2 = accept(sockfd, 0, 0); if (in1<0) perror_exit("accept"); // We have a connection. Disarm timeout. set_alarm(0); if (toys.optc) { // Do we need a tty? // TODO nommu, and -t only affects server mode...? Only do -t with optc // if (CFG_TOYBOX_FORK && (toys.optflags&FLAG_t)) // child = forkpty(&fdout, NULL, NULL, NULL); // else // Do we need to fork and/or redirect for exec? // TODO xpopen_both() here? if (FLAG(L)) NOEXIT(child = XVFORK()); if (child) { close(in1); continue; } dup2(in1, 0); dup2(in1, 1); if (FLAG(L)) dup2(in1, 2); if (in1>2) close(in1); xexec(toys.optargs); } pollinate(in1, in2, out1, out2, TT.W, TT.q); close(in1); } while (!FLAG(l)); } } cleanup: if (CFG_TOYBOX_FREE) { close(in1); close(sockfd); } }