1 files changed, 230 insertions, 0 deletions
diff --git a/toys/net/netcat.c b/toys/net/netcat.c
new file mode 100644
index 00000000..1c75eb26
--- /dev/null
+++ b/toys/net/netcat.c
@@ -0,0 +1,230 @@
+/* netcat.c - Forward stdin/stdout to a file or network connection.
+ *
+ * Copyright 2007 Rob Landley <rob@landley.net>
+ *
+ * TODO: udp, ipv6, genericize for telnet/microcom/tail-f
+
+USE_NETCAT(OLDTOY(nc, netcat, TOYFLAG_USR|TOYFLAG_BIN))
+USE_NETCAT(NEWTOY(netcat, USE_NETCAT_LISTEN("^tlL")"w#p#s:q#f:", TOYFLAG_BIN))
+
+config NETCAT
+  bool "netcat"
+  default y
+  help
+    usage: netcat [-u] [-wpq #] [-s addr] {IPADDR PORTNUM|-f FILENAME}
+
+    -f	use FILENAME (ala /dev/ttyS0) instead of network
+    -p	local port number
+    -q	SECONDS quit this many seconds after EOF on stdin.
+    -s	local ipv4 address
+    -w	SECONDS timeout for 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
+  depends on TOYBOX_FORK
+  help
+    usage: netcat [-lL COMMAND...]
+
+    -l	listen for one incoming connection.
+    -L	listen for multiple incoming connections (server mode).
+
+    The command line after -l or -L is 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
+
+config NETCAT_LISTEN_TTY
+  bool
+  default y
+  depends on NETCAT_LISTEN
+  depends on TOYBOX_FORK
+  help
+    usage: netcat [-t]
+
+    -t	allocate tty (must come before -l or -L)
+*/
+
+#define FOR_netcat
+#include "toys.h"
+
+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.
+)
+
+static void timeout(int signum)
+{
+  if (TT.wait) error_exit("Timeout");
+  // This should be xexit() but would need siglongjmp()...
+  exit(0);
+}
+
+static void set_alarm(int seconds)
+{
+  xsignal(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); // getaddrinfo
+  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) ? toys.optc :
+      (!(toys.optflags&(FLAG_l|FLAG_L)) && toys.optc!=2))
+        help_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 = xsocket(AF_INET, SOCK_STREAM, 0);
+    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 (CFG_TOYBOX_FORK && xfork()) goto cleanup;
+        close(0);
+        close(1);
+        close(2);
+      }
+
+      for (;;) {
+        pid_t child = 0;
+
+        // For -l, call accept from the _new_ process.
+
+        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) {
+            toys.stacktop = 0;
+            child = vfork();
+          }
+          if (!child && toys.optc) {
+            int fd = pollfds[0].fd;
+
+            dup2(fd, 0);
+            dup2(fd, 1);
+            if (toys.optflags&FLAG_L) 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))
+    xexec(toys.optargs);
+
+  // 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);
+  }
+}