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..fe845f5 --- /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 "libbb.h" + +#if ENABLE_DESKTOP +#include "nc_bloaty.c" +#else + +/* Lots of small differences in features + * when compared to "standard" nc + */ + +static void timeout(int signum UNUSED_PARAM) +{ + bb_error_msg_and_die("timed out"); +} + +int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; +int nc_main(int argc, char **argv) +{ + /* sfd sits _here_ only because of "repeat" option (-l -l). */ + int sfd = sfd; /* for gcc */ + int cfd = 0; + unsigned lport = 0; + SKIP_NC_SERVER(const) unsigned do_listen = 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;) + len_and_sockaddr *lsa; + fd_set readfds, testfds; + int opt; /* must be signed (getopt returns -1) */ + + 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 + if (do_listen || cfd) { + if (argc) bb_show_usage(); + } else { + if (!argc || argc > 2) bb_show_usage(); + } + } else { + if (argc != 3) bb_show_usage(); + argc--; + argv++; + } + + if (wsecs) { + signal(SIGALRM, timeout); + alarm(wsecs); + } + + if (!cfd) { + if (do_listen) { + /* create_and_bind_stream_or_die(NULL, lport) + * would've work wonderfully, but we need + * to know lsa */ + sfd = xsocket_stream(&lsa); + if (lport) + set_nport(lsa, htons(lport)); + setsockopt_reuseaddr(sfd); + xbind(sfd, &lsa->u.sa, lsa->len); + xlisten(sfd, do_listen); /* can be > 1 */ + /* If we didn't specify a port number, + * query and print it after listen() */ + if (!lport) { + socklen_t addrlen = lsa->len; + getsockname(sfd, &lsa->u.sa, &addrlen); + lport = get_nport(&lsa->u.sa); + fdprintf(2, "%d\n", ntohs(lport)); + } + close_on_exec_on(sfd); + accept_again: + cfd = accept(sfd, NULL, 0); + if (cfd < 0) + bb_perror_msg_and_die("accept"); + if (!execparam) + close(sfd); + } else { + cfd = create_and_connect_stream_or_die(argv[0], + argv[1] ? bb_lookup_port(argv[1], "tcp", 0) : 0); + } + } + + if (wsecs) { + alarm(0); + /* Non-ignored siganls revert to SIG_DFL on exec anyway */ + /*signal(SIGALRM, SIG_DFL);*/ + } + + /* -e given? */ + if (execparam) { + signal(SIGCHLD, SIG_IGN); + // With more than one -l, repeatedly act as server. + if (do_listen > 1 && vfork()) { + /* parent */ + // 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 accept_again; + } + /* child (or main thread if no multiple -l) */ + xmove_fd(cfd, 0); + xdup2(0, 1); + xdup2(0, 2); + USE_NC_EXTRA(BB_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"); + +#define iobuf bb_common_bufsiz1 + for (fd = 0; fd < FD_SETSIZE; fd++) { + if (FD_ISSET(fd, &testfds)) { + nread = safe_read(fd, iobuf, sizeof(iobuf)); + if (fd == cfd) { + if (nread < 1) + exit(EXIT_SUCCESS); + 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, iobuf, nread); + if (delay > 0) sleep(delay); + } + } + } +} +#endif |