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Diffstat (limited to 'nsock/examples/nsock_telnet.c')
| -rw-r--r-- | nsock/examples/nsock_telnet.c | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/nsock/examples/nsock_telnet.c b/nsock/examples/nsock_telnet.c new file mode 100644 index 0000000..cb2a7c0 --- /dev/null +++ b/nsock/examples/nsock_telnet.c @@ -0,0 +1,259 @@ +/*************************************************************************** + * nsock_telnet.c -- A simple "telnet" client -- a trivial example of * + * using the nsock parallel socket event library * + * * + ***********************IMPORTANT NSOCK LICENSE TERMS*********************** + * + * The nsock parallel socket event library is (C) 1999-2023 Nmap Software LLC + * This library is free software; you may redistribute and/or modify it under + * the terms of the GNU General Public License as published by the Free Software + * Foundation; Version 2. This guarantees your right to use, modify, and + * redistribute this software under certain conditions. If this license is + * unacceptable to you, Nmap Software LLC may be willing to sell alternative + * licenses (contact sales@nmap.com ). + * + * As a special exception to the GPL terms, Nmap Software LLC grants permission + * to link the code of this program with any version of the OpenSSL library + * which is distributed under a license identical to that listed in the included + * docs/licenses/OpenSSL.txt file, and distribute linked combinations including + * the two. You must obey the GNU GPL in all respects for all of the code used + * other than OpenSSL. If you modify this file, you may extend this exception to + * your version of the file, but you are not obligated to do so. + * + * If you received these files with a written license agreement stating terms + * other than the (GPL) terms above, then that alternative license agreement + * takes precedence over this comment. + * + * Source is provided to this software because we believe users have a right to + * know exactly what a program is going to do before they run it. This also + * allows you to audit the software for security holes. + * + * Source code also allows you to port Nmap to new platforms, fix bugs, and add + * new features. You are highly encouraged to send your changes to the + * dev@nmap.org mailing list for possible incorporation into the main + * distribution. By sending these changes to Fyodor or one of the Insecure.Org + * development mailing lists, or checking them into the Nmap source code + * repository, it is understood (unless you specify otherwise) that you are + * offering the Nmap Project (Nmap Software LLC) the unlimited, non-exclusive + * right to reuse, modify, and relicense the code. Nmap will always be available + * Open Source, but this is important because the inability to relicense code + * has caused devastating problems for other Free Software projects (such as KDE + * and NASM). We also occasionally relicense the code to third parties as + * discussed above. If you wish to specify special license conditions of your + * contributions, just say so when you send them. + * + * This program is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS + * FOR A PARTICULAR PURPOSE. See the GNU General Public License v2.0 for more + * details (http://www.gnu.org/licenses/gpl-2.0.html). + * + ***************************************************************************/ + + +#include "nsock.h" + +#include <stdio.h> +#include <stdlib.h> +#include <sys/socket.h> +#include <netinet/in.h> +#include <arpa/inet.h> +#include <netdb.h> +#include <unistd.h> +#include <stdlib.h> +#include <string.h> +#include <stdio.h> +#include <assert.h> +#include <sys/time.h> + +#include <openssl/ssl.h> +#include <openssl/err.h> +/* #include <nbase.h> */ + +/* from nbase.h */ +int socket_errno(); + + +extern char *optarg; + +extern int optind; + +struct telnet_state { + nsock_iod tcp_nsi; + nsock_iod stdin_nsi; + nsock_event_id latest_readtcpev; + nsock_event_id latest_readstdinev; + void *ssl_session; +}; + +/* Tries to resolve given hostname and stores + result in ip . returns 0 if hostname cannot + be resolved */ +int resolve(char *hostname, struct in_addr *ip) { + struct hostent *h; + + if (!hostname || !*hostname) { + fprintf(stderr, "NULL or zero-length hostname passed to resolve(). Quitting.\n"); + exit(1); + } + + if (inet_aton(hostname, ip)) + return 1; /* damn, that was easy ;) */ + if ((h = gethostbyname(hostname))) { + memcpy(ip, h->h_addr_list[0], sizeof(struct in_addr)); + return 1; + } + return 0; +} + +void telnet_event_handler(nsock_pool nsp, nsock_event nse, void *mydata) { + nsock_iod nsi = nse_iod(nse); + enum nse_status status = nse_status(nse); + enum nse_type type = nse_type(nse); + struct sockaddr_in peer; + struct telnet_state *ts; + int nbytes; + char *str; + int read_timeout = -1; + int write_timeout = 2000; + ts = (struct telnet_state *)mydata; + + printf("telnet_event_handler: Received callback of type %s with status %s\n", nse_type2str(type), nse_status2str(status)); + + if (status == NSE_STATUS_SUCCESS) { + switch (type) { + case NSE_TYPE_CONNECT: + case NSE_TYPE_CONNECT_SSL: + nsock_iod_get_communication_info(nsi, NULL, NULL, NULL, (struct sockaddr *)&peer, sizeof peer); + printf("Successfully connected %sto %s:%hu -- start typing lines\n", (type == NSE_TYPE_CONNECT_SSL) ? "(SSL!) " : "", inet_ntoa(peer.sin_addr), ntohs(peer.sin_port)); + /* First of all, lets add STDIN to our list of watched filehandles */ + if ((ts->stdin_nsi = nsock_iod_new2(nsp, STDIN_FILENO, NULL)) == NULL) { + fprintf(stderr, "Failed to create stdin msi\n"); + exit(1); + } + + /* Now lets read from stdin and the network, line buffered (by nsock) */ + ts->latest_readtcpev = nsock_readlines(nsp, ts->tcp_nsi, telnet_event_handler, read_timeout, ts, 1); + ts->latest_readstdinev = nsock_readlines(nsp, ts->stdin_nsi, telnet_event_handler, read_timeout, ts, 1); + break; + case NSE_TYPE_READ: + str = nse_readbuf(nse, &nbytes); + if (nsi == ts->tcp_nsi) { + printf("%s", str); + /* printf("Read from tcp socket (%d bytes):\n%s", nbytes, str); */ + ts->latest_readtcpev = nsock_readlines(nsp, ts->tcp_nsi, telnet_event_handler, read_timeout, ts, 1); + } else { + /* printf("Read from stdin (%d bytes):\n%s", nbytes, str); */ + nsock_write(nsp, ts->tcp_nsi, telnet_event_handler, write_timeout, ts, str, nbytes); + ts->latest_readstdinev = nsock_readlines(nsp, ts->stdin_nsi, telnet_event_handler, read_timeout, ts, 1); + } + break; + case NSE_TYPE_WRITE: + /* Nothing to do, really */ + break; + case NSE_TYPE_TIMER: + break; + default: + fprintf(stderr, "telnet_event_handler: Got bogus type -- quitting\n"); + exit(1); + break; + } + } else if (status == NSE_STATUS_EOF) { + printf("Got EOF from %s\nCancelling outstanding readevents.\n", (nsi == ts->tcp_nsi) ? "tcp socket" : "stdin"); + /* One of these is the event I am currently handling! But I wanted to + be evil when testing this out... */ + if (nsock_event_cancel(nsp, ts->latest_readtcpev, 1) != 0) { + printf("Cancelled tcp event: %li\n", ts->latest_readtcpev); + } + if (nsock_event_cancel(nsp, ts->latest_readstdinev, 1) != 0) { + printf("Cancelled stdin event: %li\n", ts->latest_readstdinev); + } + } else if (status == NSE_STATUS_ERROR) { + if (nsock_iod_check_ssl(nsi)) { + printf("SSL %s failed: %s\n", nse_type2str(type), ERR_error_string(ERR_get_error(), NULL)); + } else { + int err; + + err = nse_errorcode(nse); + printf("%s failed: (%d) %s\n", nse_type2str(type), err, strerror(err)); + } + } + return; +} + +void usage() { + fprintf(stderr, "\nUsage: nsock_telnet [-s] <hostnameorip> [portnum]\n" " Where -s enables SSL for the connection\n\n"); + exit(1); +} + +int main(int argc, char *argv[]) { + struct in_addr target; + nsock_pool nsp; + nsock_event_id ev; + unsigned short portno; + enum nsock_loopstatus loopret; + struct telnet_state ts; + int c; + int usessl = 0; + struct timeval now; + struct sockaddr_in taddr; + + ts.stdin_nsi = NULL; + + while ((c = getopt(argc, argv, "s")) != -1) { + switch (c) { + case 's': + usessl = 1; + break; + default: + usage(); + break; + } + } + + if (argc - optind <= 0 || argc - optind > 2) + usage(); + + + if (!resolve(argv[optind], &target)) { + fprintf(stderr, "Failed to resolve target host: %s\nQUITTING.\n", argv[optind]); + exit(1); + } + optind++; + + if (optind < argc) + portno = atoi(argv[optind]); + else + portno = 23; + + /* OK, we start with creating a p00l */ + if ((nsp = nsock_pool_new(NULL)) == NULL) { + fprintf(stderr, "Failed to create new pool. QUITTING.\n"); + exit(1); + } + + gettimeofday(&now, NULL); + + if ((ts.tcp_nsi = nsock_iod_new(nsp, NULL)) == NULL) { + fprintf(stderr, "Failed to create new nsock_iod. QUITTING.\n"); + exit(1); + } + + taddr.sin_family = AF_INET; + taddr.sin_addr = target; + taddr.sin_port = portno; + + if (usessl) { + ts.ssl_session = NULL; + ev = nsock_connect_ssl(nsp, ts.tcp_nsi, telnet_event_handler, 10000, &ts, (struct sockaddr *)&taddr, sizeof taddr, IPPROTO_TCP, portno, ts.ssl_session); + } else + ev = nsock_connect_tcp(nsp, ts.tcp_nsi, telnet_event_handler, 10000, &ts, (struct sockaddr *)&taddr, sizeof taddr, portno); + + printf("The event id is %lu -- initiating l00p\n", ev); + + /* Now lets get this party started right! */ + loopret = nsock_loop(nsp, -1); + + printf("nsock_loop returned %d\n", (int)loopret); + + return 0; +} |