diff options
Diffstat (limited to 'networking/nc.c')
| -rw-r--r-- | networking/nc.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/networking/nc.c b/networking/nc.c new file mode 100644 index 0000000..5fd9242 --- /dev/null +++ b/networking/nc.c @@ -0,0 +1,201 @@ +/* vi: set sw=4 ts=4: */ +/* nc: mini-netcat - built from the ground up for LRP + * + * Copyright (C) 1998, 1999 Charles P. Wright + * Copyright (C) 1998 Dave Cinege + * + * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. + */ + +#include "busybox.h" + +static void timeout(int signum) +{ + bb_error_msg_and_die("timed out"); +} + +int nc_main(int argc, char **argv) +{ + int sfd = 0; + int cfd = 0; + SKIP_NC_SERVER(const) unsigned do_listen = 0; + SKIP_NC_SERVER(const) unsigned lport = 0; + SKIP_NC_EXTRA (const) unsigned wsecs = 0; + SKIP_NC_EXTRA (const) unsigned delay = 0; + SKIP_NC_EXTRA (const int execparam = 0;) + USE_NC_EXTRA (char **execparam = NULL;) + struct sockaddr_in address; + fd_set readfds, testfds; + int opt; /* must be signed (getopt returns -1) */ + + memset(&address, 0, sizeof(address)); + + if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) { + /* getopt32 is _almost_ usable: + ** it cannot handle "... -e prog -prog-opt" */ + while ((opt = getopt(argc, argv, + "" USE_NC_SERVER("lp:") USE_NC_EXTRA("w:i:f:e:") )) > 0 + ) { + if (ENABLE_NC_SERVER && opt=='l') USE_NC_SERVER(do_listen++); + else if (ENABLE_NC_SERVER && opt=='p') USE_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0)); + else if (ENABLE_NC_EXTRA && opt=='w') USE_NC_EXTRA( wsecs = xatou(optarg)); + else if (ENABLE_NC_EXTRA && opt=='i') USE_NC_EXTRA( delay = xatou(optarg)); + else if (ENABLE_NC_EXTRA && opt=='f') USE_NC_EXTRA( cfd = xopen(optarg, O_RDWR)); + else if (ENABLE_NC_EXTRA && opt=='e' && optind<=argc) { + /* We cannot just 'break'. We should let getopt finish. + ** Or else we won't be able to find where + ** 'host' and 'port' params are + ** (think "nc -w 60 host port -e prog"). */ + USE_NC_EXTRA( + char **p; + // +2: one for progname (optarg) and one for NULL + execparam = xzalloc(sizeof(char*) * (argc - optind + 2)); + p = execparam; + *p++ = optarg; + while (optind < argc) { + *p++ = argv[optind++]; + } + ) + /* optind points to argv[arvc] (NULL) now. + ** FIXME: we assume that getopt will not count options + ** possibly present on "-e prog args" and will not + ** include them into final value of optind + ** which is to be used ... */ + } else bb_show_usage(); + } + argv += optind; /* ... here! */ + argc -= optind; + // -l and -f don't mix + if (do_listen && cfd) bb_show_usage(); + // Listen or file modes need zero arguments, client mode needs 2 + opt = ((do_listen || cfd) ? 0 : 2); + if (argc != opt) + bb_show_usage(); + } else { + if (argc != 3) bb_show_usage(); + argc--; + argv++; + } + + if (wsecs) { + signal(SIGALRM, timeout); + alarm(wsecs); + } + + if (!cfd) { + sfd = xsocket(AF_INET, SOCK_STREAM, 0); + fcntl(sfd, F_SETFD, FD_CLOEXEC); + setsockopt_reuseaddr(sfd); + address.sin_family = AF_INET; + + // Set local port. + + if (lport != 0) { + address.sin_port = lport; + xbind(sfd, (struct sockaddr *) &address, sizeof(address)); + } + + if (do_listen) { + socklen_t addrlen = sizeof(address); + + xlisten(sfd, do_listen); + + // If we didn't specify a port number, query and print it to stderr. + + if (!lport) { + socklen_t len = sizeof(address); + getsockname(sfd, &address, &len); + fdprintf(2, "%d\n", SWAP_BE16(address.sin_port)); + } + repeatyness: + cfd = accept(sfd, (struct sockaddr *) &address, &addrlen); + if (cfd < 0) + bb_perror_msg_and_die("accept"); + + if (!execparam) close(sfd); + } else { + struct hostent *hostinfo; + hostinfo = xgethostbyname(argv[0]); + + address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list; + address.sin_port = bb_lookup_port(argv[1], "tcp", 0); + + if (connect(sfd, (struct sockaddr *) &address, sizeof(address)) < 0) + bb_perror_msg_and_die("connect"); + cfd = sfd; + } + } + + if (wsecs) { + alarm(0); + signal(SIGALRM, SIG_DFL); + } + + /* -e given? */ + if (execparam) { + if (cfd) { + signal(SIGCHLD, SIG_IGN); + dup2(cfd, 0); + close(cfd); + } + dup2(0, 1); + dup2(0, 2); + + // With more than one -l, repeatedly act as server. + + if (do_listen > 1 && vfork()) { + // This is a bit weird as cleanup goes, since we wind up with no + // stdin/stdout/stderr. But it's small and shouldn't hurt anything. + // We check for cfd == 0 above. + logmode = LOGMODE_NONE; + close(0); + close(1); + close(2); + + goto repeatyness; + } + USE_NC_EXTRA(execvp(execparam[0], execparam);) + /* Don't print stuff or it will go over the wire.... */ + _exit(127); + } + + // Select loop copying stdin to cfd, and cfd to stdout. + + FD_ZERO(&readfds); + FD_SET(cfd, &readfds); + FD_SET(STDIN_FILENO, &readfds); + + for (;;) { + int fd; + int ofd; + int nread; + + testfds = readfds; + + if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0) + bb_perror_msg_and_die("select"); + + for (fd = 0; fd < FD_SETSIZE; fd++) { + if (FD_ISSET(fd, &testfds)) { + nread = safe_read(fd, bb_common_bufsiz1, + sizeof(bb_common_bufsiz1)); + + if (fd == cfd) { + if (nread<1) exit(0); + ofd = STDOUT_FILENO; + } else { + if (nread<1) { + // Close outgoing half-connection so they get EOF, but + // leave incoming alone so we can see response. + shutdown(cfd, 1); + FD_CLR(STDIN_FILENO, &readfds); + } + ofd = cfd; + } + + xwrite(ofd, bb_common_bufsiz1, nread); + if (delay > 0) sleep(delay); + } + } + } +} |