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-rw-r--r--toys/other/netcat.c232
1 files changed, 232 insertions, 0 deletions
diff --git a/toys/other/netcat.c b/toys/other/netcat.c
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+/* vi: set sw=4 ts=4:
+ *
+ * nc: mini-netcat - Forward stdin/stdout to a file or network connection.
+ *
+ * Copyright 2007 Rob Landley <rob@landley.net>
+ *
+ * Not in SUSv3.
+
+USE_NETCAT(OLDTOY(nc, netcat, USE_NETCAT_LISTEN("tl^L^")"w#p#s:q#f:", TOYFLAG_BIN))
+USE_NETCAT(NEWTOY(netcat, USE_NETCAT_LISTEN("tl^L^")"w#p#s:q#f:", TOYFLAG_BIN))
+
+config NETCAT
+ bool "netcat"
+ default y
+ help
+ usage: netcat [-wpq #] [-s addr] {IPADDR PORTNUM|-f FILENAME|-let} [-e COMMAND]
+
+ -w SECONDS timeout for connection
+ -p local port number
+ -s local ipv4 address
+ -q SECONDS quit this many seconds after EOF on stdin.
+ -f use FILENAME (ala /dev/ttyS0) instead of network
+
+ Use "stty 115200 -F /dev/ttyS0 && stty raw -echo -ctlecho" with
+ netcat -f to connect to a serial port.
+
+
+config NETCAT_LISTEN
+ bool "netcat sever options (-let)"
+ default y
+ depends on NETCAT
+ help
+ -t allocate tty (must come before -l or -L)
+ -l listen for one incoming connection.
+ -L listen for multiple incoming connections (server mode).
+
+ Any additional command line arguments after -l or -L are executed
+ to handle each incoming connection. If none, the connection is
+ forwarded to stdin/stdout.
+
+ For a quick-and-dirty server, try something like:
+ netcat -s 127.0.0.1 -p 1234 -tL /bin/bash -l
+*/
+
+#include "toys.h"
+#include "toynet.h"
+
+DEFINE_GLOBALS(
+ char *filename; // -f read from filename instead of network
+ long quit_delay; // -q Exit after EOF from stdin after # seconds.
+ char *source_address; // -s Bind to a specific source address.
+ long port; // -p Bind to a specific source port.
+ long wait; // -w Wait # seconds for a connection.
+)
+
+#define TT this.netcat
+
+#define FLAG_f 1
+#define FLAG_L 32
+#define FLAG_l 64
+#define FLAG_t 128
+
+static void timeout(int signum)
+{
+ if (TT.wait) error_exit("Timeout");
+ exit(0);
+}
+
+static void set_alarm(int seconds)
+{
+ signal(SIGALRM, seconds ? timeout : SIG_DFL);
+ alarm(seconds);
+}
+
+// Translate x.x.x.x numeric IPv4 address, or else DNS lookup an IPv4 name.
+static void lookup_name(char *name, uint32_t *result)
+{
+ struct hostent *hostbyname;
+
+ hostbyname = gethostbyname(name);
+ if (!hostbyname) error_exit("no host '%s'", name);
+ *result = *(uint32_t *)*hostbyname->h_addr_list;
+}
+
+// Worry about a fancy lookup later.
+static void lookup_port(char *str, uint16_t *port)
+{
+ *port = SWAP_BE16(atoi(str));
+}
+
+void netcat_main(void)
+{
+ int sockfd=-1, pollcount=2;
+ struct pollfd pollfds[2];
+
+ memset(pollfds, 0, 2*sizeof(struct pollfd));
+ pollfds[0].events = pollfds[1].events = POLLIN;
+ set_alarm(TT.wait);
+
+ // The argument parsing logic can't make "<2" conditional on other
+ // arguments like -f and -l, so we do it by hand here.
+ if (toys.optflags&FLAG_f) {
+ if (toys.optc) toys.exithelp++;
+ } else if (!(toys.optflags&(FLAG_l|FLAG_L)) && toys.optc!=2) toys.exithelp++;
+
+ if (toys.exithelp) error_exit("Argument count wrong");
+
+ if (TT.filename) pollfds[0].fd = xopen(TT.filename, O_RDWR);
+ else {
+ int temp;
+ struct sockaddr_in address;
+
+ // Setup socket
+ sockfd = socket(AF_INET, SOCK_STREAM, 0);
+ if (-1 == sockfd) perror_exit("socket");
+ fcntl(sockfd, F_SETFD, FD_CLOEXEC);
+ temp = 1;
+ setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &temp, sizeof(temp));
+ memset(&address, 0, sizeof(address));
+ address.sin_family = AF_INET;
+ if (TT.source_address || TT.port) {
+ address.sin_port = SWAP_BE16(TT.port);
+ if (TT.source_address)
+ lookup_name(TT.source_address, (uint32_t *)&address.sin_addr);
+ if (bind(sockfd, (struct sockaddr *)&address, sizeof(address)))
+ perror_exit("bind");
+ }
+
+ // Dial out
+
+ if (!CFG_NETCAT_LISTEN || !(toys.optflags&(FLAG_L|FLAG_l))) {
+ // Figure out where to dial out to.
+ lookup_name(*toys.optargs, (uint32_t *)&address.sin_addr);
+ lookup_port(toys.optargs[1], &address.sin_port);
+ temp = connect(sockfd, (struct sockaddr *)&address, sizeof(address));
+ if (temp<0) perror_exit("connect");
+ pollfds[0].fd = sockfd;
+
+ // Listen for incoming connections
+
+ } else {
+ socklen_t len = sizeof(address);
+
+ if (listen(sockfd, 5)) error_exit("listen");
+ if (!TT.port) {
+ getsockname(sockfd, (struct sockaddr *)&address, &len);
+ printf("%d\n", SWAP_BE16(address.sin_port));
+ fflush(stdout);
+ }
+ // Do we need to return immediately because -l has arguments?
+
+ if ((toys.optflags&FLAG_l) && toys.optc) {
+ if (fork()) goto cleanup;
+ close(0);
+ close(1);
+ close(2);
+ }
+
+ for (;;) {
+ pid_t child = 0;
+
+ // For -l, call accept from the _new_ thread.
+
+ pollfds[0].fd = accept(sockfd, (struct sockaddr *)&address,
+ &len);
+ if (pollfds[0].fd<0) perror_exit("accept");
+
+ // Do we need a tty?
+
+ if (toys.optflags&FLAG_t)
+ child = forkpty(&(pollfds[1].fd), NULL, NULL, NULL);
+
+ // Do we need to fork and/or redirect for exec?
+
+ else {
+ if (toys.optflags&FLAG_L) child = fork();
+ if (!child && toys.optc) {
+ int fd = pollfds[0].fd;
+
+ if (!temp) close(sockfd);
+ dup2(fd, 0);
+ dup2(fd, 1);
+ dup2(fd, 2);
+ if (fd>2) close(fd);
+ }
+ }
+
+ if (child<0) error_msg("Fork failed\n");
+ if (child<1) break;
+ close(pollfds[0].fd);
+ }
+ }
+ }
+
+ // We have a connection. Disarm timeout.
+ // (Does not play well with -L, but what _should_ that do?)
+ set_alarm(0);
+
+ if (CFG_NETCAT_LISTEN && (toys.optflags&(FLAG_L|FLAG_l) && toys.optc)) {
+ execvp(*toys.optargs, toys.optargs);
+ error_exit("Exec failed");
+ }
+
+ // Poll loop copying stdin->socket and socket->stdout.
+ for (;;) {
+ int i;
+
+ if (0>poll(pollfds, pollcount, -1)) perror_exit("poll");
+
+ for (i=0; i<pollcount; i++) {
+ if (pollfds[i].revents & POLLIN) {
+ int len = read(pollfds[i].fd, toybuf, sizeof(toybuf));
+ if (len<1) goto dohupnow;
+ xwrite(i ? pollfds[0].fd : 1, toybuf, len);
+ } else if (pollfds[i].revents & POLLHUP) {
+dohupnow:
+ // Close half-connection. This is needed for things like
+ // "echo GET / | netcat landley.net 80"
+ if (i) {
+ shutdown(pollfds[0].fd, SHUT_WR);
+ pollcount--;
+ set_alarm(TT.quit_delay);
+ } else goto cleanup;
+ }
+ }
+ }
+cleanup:
+ if (CFG_TOYBOX_FREE) {
+ close(pollfds[0].fd);
+ close(sockfd);
+ }
+}
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