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-rw-r--r--toys/pending/telnetd.c451
1 files changed, 451 insertions, 0 deletions
diff --git a/toys/pending/telnetd.c b/toys/pending/telnetd.c
new file mode 100644
index 00000000..115b3840
--- /dev/null
+++ b/toys/pending/telnetd.c
@@ -0,0 +1,451 @@
+/* telnetd.c - Telnet Server
+ *
+ * Copyright 2013 Sandeep Sharma <sandeep.jack2756@gmail.com>
+ * Copyright 2013 Kyungwan Han <asura321@gmail.com>
+ *
+USE_TELNETD(NEWTOY(telnetd, "w#<0b:p#<0>65535=23f:l:FSKi[!wi]", TOYFLAG_USR|TOYFLAG_BIN))
+
+config TELNETD
+ bool "telnetd"
+ default n
+ help
+ Handle incoming telnet connections
+
+ -l LOGIN Exec LOGIN on connect
+ -f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue
+ -K Close connection as soon as login exits
+ -p PORT Port to listen on
+ -b ADDR[:PORT] Address to bind to
+ -F Run in foreground
+ -i Inetd mode
+ -w SEC Inetd 'wait' mode, linger time SEC
+ -S Log to syslog (implied by -i or without -F and -w)
+*/
+
+#define FOR_telnetd
+#include "toys.h"
+#include <utmp.h>
+GLOBALS(
+ char *login_path;
+ char *issue_path;
+ int port;
+ char *host_addr;
+ long w_sec;
+
+ int gmax_fd;
+ int sig;
+ pid_t fork_pid;
+)
+
+
+# define IAC 255 /* interpret as command: */
+# define DONT 254 /* you are not to use option */
+# define DO 253 /* please, you use option */
+# define WONT 252 /* I won't use option */
+# define WILL 251 /* I will use option */
+# define SB 250 /* interpret as subnegotiation */
+# define SE 240 /* end sub negotiation */
+# define NOP 241 /* No Operation */
+# define TELOPT_ECHO 1 /* echo */
+# define TELOPT_SGA 3 /* suppress go ahead */
+# define TELOPT_TTYPE 24 /* terminal type */
+# define TELOPT_NAWS 31 /* window size */
+
+#define BUFSIZE 4*1024
+struct term_session {
+ int new_fd, pty_fd;
+ pid_t child_pid;
+ int buff1_avail, buff2_avail;
+ int buff1_written, buff2_written;
+ int rem; //unprocessed data from socket
+ char buff1[BUFSIZE], buff2[BUFSIZE];
+ struct term_session *next;
+};
+
+struct term_session *session_list = NULL;
+
+static void get_sockaddr(char *host, void *buf)
+{
+ in_port_t port_num = htons(TT.port);
+ struct addrinfo hints, *result;
+ int status, af = AF_UNSPEC;
+ char *s;
+
+ // [ipv6]:port or exactly one :
+ if (*host == '[') {
+ host++;
+ s = strchr(host, ']');
+ if (s) *s++ = 0;
+ else error_exit("bad address '%s'", host-1);
+ af = AF_INET6;
+ } else {
+ s = strrchr(host, ':');
+ if (s && strchr(host, ':') == s) {
+ *s = 0;
+ af = AF_INET;
+ } else if (s && strchr(host, ':') != s) {
+ af = AF_INET6;
+ s = 0;
+ }
+ }
+
+ if (s++) {
+ char *ss;
+ unsigned long p = strtoul(s, &ss, 0);
+ if (!*s || *ss || p > 65535) error_exit("bad port '%s'", s);
+ port_num = htons(p);
+ }
+
+ memset(&hints, 0 , sizeof(struct addrinfo));
+ hints.ai_family = af;
+ hints.ai_socktype = SOCK_STREAM;
+
+ status = getaddrinfo(host, NULL, &hints, &result);
+ if (status) error_exit("bad address '%s' : %s", host, gai_strerror(status));
+
+ memcpy(buf, result->ai_addr, result->ai_addrlen);
+ freeaddrinfo(result);
+
+ if (af == AF_INET) ((struct sockaddr_in*)buf)->sin_port = port_num;
+ else ((struct sockaddr_in6*)buf)->sin6_port = port_num;
+}
+
+static void utmp_entry(void)
+{
+ struct utmp entry;
+ struct utmp *utp_ptr;
+ pid_t pid = getpid();
+
+ utmpname(_PATH_UTMP);
+ setutent(); //start from start
+ while ((utp_ptr = getutent()) != NULL) {
+ if (utp_ptr->ut_pid == pid && utp_ptr->ut_type >= INIT_PROCESS) break;
+ }
+ if (!utp_ptr) entry.ut_type = DEAD_PROCESS;
+ time(&entry.ut_time);
+ setutent();
+ pututline(&entry);
+}
+
+static int listen_socket(void)
+{
+ int s, af = AF_INET, yes = 1;
+ char buf[sizeof(struct sockaddr_storage)];
+
+ memset(buf, 0, sizeof(buf));
+ if (toys.optflags & FLAG_b) {
+ get_sockaddr(TT.host_addr, buf);
+ af = ((struct sockaddr *)buf)->sa_family;
+ } else {
+ ((struct sockaddr_in*)buf)->sin_port = htons(TT.port);
+ ((struct sockaddr_in*)buf)->sin_family = af;
+ }
+ s = xsocket(af, SOCK_STREAM, 0);
+ if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *)&yes, sizeof(yes)) == -1)
+ perror_exit("setsockopt");
+
+ if (bind(s, (struct sockaddr *)buf, ((af == AF_INET)?
+ (sizeof(struct sockaddr_in)):(sizeof(struct sockaddr_in6)))) == -1) {
+ close(s);
+ perror_exit("bind");
+ }
+
+ if (listen(s, 1) < 0) perror_exit("listen");
+ return s;
+}
+
+static void write_issue(char *tty)
+{
+ int size;
+ char ch = 0;
+ struct utsname u;
+ int fd = open(TT.issue_path, O_RDONLY);
+
+ if (fd < 0) return ;
+ uname(&u);
+ while ((size = readall(fd, &ch, 1)) > 0) {
+ if (ch == '\\' || ch == '%') {
+ if (readall(fd, &ch, 1) <= 0) perror_exit("readall!");
+ if (ch == 's') fputs(u.sysname, stdout);
+ if (ch == 'n'|| ch == 'h') fputs(u.nodename, stdout);
+ if (ch == 'r') fputs(u.release, stdout);
+ if (ch == 'm') fputs(u.machine, stdout);
+ if (ch == 'l') fputs(tty, stdout);
+ }
+ else if (ch == '\n') {
+ fputs("\n\r\0", stdout);
+ } else fputc(ch, stdout);
+ }
+ fflush(NULL);
+ close(fd);
+}
+
+static int new_session(int sockfd)
+{
+ char *argv_login[2]; //arguments for execvp cmd, NULL
+ char tty_name[30]; //tty name length.
+ int fd, flags, i = 1;
+ char intial_iacs[] = {IAC, DO, TELOPT_ECHO, IAC, DO, TELOPT_NAWS,
+ IAC, WILL, TELOPT_ECHO, IAC, WILL, TELOPT_SGA };
+
+ setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &i, sizeof(i));
+ flags = fcntl(sockfd, F_GETFL);
+ fcntl(sockfd, F_SETFL, flags | O_NONBLOCK);
+ if (toys.optflags & FLAG_i) fcntl((sockfd + 1), F_SETFL, flags | O_NONBLOCK);
+
+ writeall((toys.optflags & FLAG_i)?1:sockfd, intial_iacs, sizeof(intial_iacs));
+ if ((TT.fork_pid = forkpty(&fd, tty_name, NULL, NULL)) > 0) {
+ flags = fcntl(fd, F_GETFL);
+ fcntl(fd, F_SETFL, flags | O_NONBLOCK);
+ return fd;
+ }
+ if (TT.fork_pid < 0) perror_exit("fork");
+ write_issue(tty_name);
+ argv_login[0] = strdup(TT.login_path);
+ argv_login[1] = NULL;
+ execvp(argv_login[0], argv_login);
+ exit(EXIT_FAILURE);
+}
+
+static int handle_iacs(struct term_session *tm, int c, int fd)
+{
+ char *curr ,*start,*end;
+ int i = 0;
+
+ curr = start = tm->buff2+tm->buff2_avail;
+ end = tm->buff2 + c -1;
+ tm->rem = 0;
+ while (curr <= end) {
+ if (*curr != IAC){
+
+ if (*curr != '\r') {
+ toybuf[i++] = *curr++;
+ continue;
+ } else {
+ toybuf[i++] = *curr++;
+ curr++;
+ if (curr < end && (*curr == '\n' || *curr == '\0'))
+ curr++;
+ continue;
+ }
+ }
+
+ if ((curr + 1) > end) {
+ tm->rem = 1;
+ break;
+ }
+ if (*(curr+1) == IAC) { //IAC as data --> IAC IAC
+ toybuf[i++] = *(curr+1);
+ curr += 2; //IAC IAC --> 2 bytes
+ continue;
+ }
+ if (*(curr + 1) == NOP || *(curr + 1) == SE) {
+ curr += 2;
+ continue;
+ }
+
+ if (*(curr + 1) == SB ) {
+ if (*(curr+2) == TELOPT_NAWS) {
+ struct winsize ws;
+ if ((curr+8) >= end) { //ensure we have data to process.
+ tm->rem = end - curr;
+ break;
+ }
+ ws.ws_col = (curr[3] << 8) | curr[4];
+ ws.ws_row = (curr[5] << 8) | curr[6];
+ ioctl(fd, TIOCSWINSZ, (char *)&ws);
+ curr += 9;
+ continue;
+ } else { //eat non-supported sub neg. options.
+ curr++, tm->rem++;
+ while (*curr != IAC && curr <= end) {
+ curr++;
+ tm->rem++;
+ }
+ if (*curr == IAC) {
+ tm->rem = 0;
+ continue;
+ } else break;
+ }
+ }
+ curr += 3; //skip non-supported 3 bytes.
+ }
+ memcpy(start, toybuf, i);
+ memcpy(start + i, end - tm->rem, tm->rem); //put remaining if we break;
+ return i;
+}
+
+static int dup_iacs(char *start, int fd, int len)
+{
+ char arr[] = {IAC, IAC};
+ char *needle = NULL;
+ int ret = 0, c, count = 0;
+
+ while (len) {
+ if (*start == IAC) {
+ count = writeall(fd, arr, sizeof(arr));
+ if (count != 2) break; //short write
+ start++;
+ ret++;
+ len--;
+ continue;
+ }
+ needle = memchr(start, IAC, len);
+ if (needle) c = needle - start;
+ else c = len;
+ count = writeall(fd, start, c);
+ if (count < 0) break;
+ len -= count;
+ ret += count;
+ start += count;
+ }
+ return ret;
+}
+
+static void kill_session(void)
+{
+ int status;
+ struct term_session *tm, *prev = NULL;
+ pid_t pid = wait(&status);
+ TT.sig = 0; //ASAP
+
+ tm = session_list;
+ if (toys.optflags & FLAG_i) exit(EXIT_SUCCESS);
+
+ if (pid < 0) return;
+ while (tm) {
+ if (tm->child_pid == pid) break;
+ prev = tm;
+ tm = tm->next;
+ }
+ if (!tm) return; //paranoia
+ if (!prev) session_list = session_list->next;
+ else prev->next = tm->next;
+ utmp_entry();
+ xclose(tm->pty_fd);
+ xclose(tm->new_fd);
+ free(tm);
+}
+
+static void session_handler(int sig)
+{
+ TT.sig = sig;
+}
+
+void telnetd_main(void)
+{
+ errno = 0;
+ fd_set rd, wr;
+ struct term_session *tm = NULL;
+ struct timeval tv, *tv_ptr = NULL;
+ int pty_fd, new_fd, c = 0, w, master_fd = 0;
+ int inetd_m = (toys.optflags & FLAG_i);
+
+ TT.sig = 0;
+ if (!(toys.optflags & FLAG_l)) TT.login_path = "/bin/login";
+ if (!(toys.optflags & FLAG_f)) TT.issue_path = "/etc/issue.net";
+ if (toys.optflags & FLAG_w) toys.optflags |= FLAG_F;
+ if (!inetd_m) {
+ master_fd = listen_socket();
+ fcntl(master_fd, F_SETFD, FD_CLOEXEC);
+ if (master_fd > TT.gmax_fd) TT.gmax_fd = master_fd;
+ if (!(toys.optflags & FLAG_F)) daemonize();
+ } else {
+ pty_fd = new_session(master_fd); //master_fd = 0
+ if (pty_fd > TT.gmax_fd) TT.gmax_fd = pty_fd;
+ tm = xzalloc(sizeof(struct term_session));
+ tm->child_pid = TT.fork_pid;
+ tm->new_fd = 0;
+ tm->pty_fd = pty_fd;
+ if (session_list) {
+ tm->next = session_list;
+ session_list = tm;
+ } else session_list = tm;
+ }
+
+ if ((toys.optflags & FLAG_w) && !session_list) {
+ tv.tv_sec = TT.w_sec;
+ tv.tv_usec = 0;
+ tv_ptr = &tv;
+ }
+ signal(SIGCHLD, session_handler);
+
+ for (;;) {
+ FD_ZERO(&rd);
+ FD_ZERO(&wr);
+ if (!inetd_m) FD_SET(master_fd, &rd);
+
+ tm = session_list;
+ while (tm) {
+
+ if (tm->pty_fd > 0 && tm->buff1_avail < BUFSIZE) FD_SET(tm->pty_fd, &rd);
+ if (tm->new_fd >= 0 && tm->buff2_avail < BUFSIZE) FD_SET(tm->new_fd, &rd);
+ if (tm->pty_fd > 0 && (tm->buff2_avail - tm->buff2_written) > 0)
+ FD_SET(tm->pty_fd, &wr);
+ if (tm->new_fd >= 0 && (tm->buff1_avail - tm->buff1_written) > 0)
+ FD_SET(tm->new_fd, &wr);
+ tm = tm->next;
+ }
+
+
+ int r = select(TT.gmax_fd + 1, &rd, &wr, NULL, tv_ptr);
+ if (!r) return; //timeout
+ if (r < -1) continue;
+
+ if (!inetd_m && FD_ISSET(master_fd, &rd)) { //accept new connection
+ new_fd = accept(master_fd, NULL, NULL);
+ if (new_fd < 0) continue;
+ tv_ptr = NULL;
+ fcntl(new_fd, F_SETFD, FD_CLOEXEC);
+ if (new_fd > TT.gmax_fd) TT.gmax_fd = new_fd;
+ pty_fd = new_session(new_fd);
+ if (pty_fd > TT.gmax_fd) TT.gmax_fd = pty_fd;
+
+ tm = xzalloc(sizeof(struct term_session));
+ tm->child_pid = TT.fork_pid;
+ tm->new_fd = new_fd;
+ tm->pty_fd = pty_fd;
+ if (session_list) {
+ tm->next = session_list;
+ session_list = tm;
+ } else session_list = tm;
+ }
+
+ tm = session_list;
+ for (;tm;tm=tm->next) {
+ if (FD_ISSET(tm->pty_fd, &rd)) {
+ if ((c = read(tm->pty_fd, tm->buff1 + tm->buff1_avail,
+ BUFSIZE-tm->buff1_avail)) <= 0) break;
+ tm->buff1_avail += c;
+ if ((w = dup_iacs(tm->buff1 + tm->buff1_written, tm->new_fd + inetd_m,
+ tm->buff1_avail - tm->buff1_written)) < 0) break;
+ tm->buff1_written += w;
+ }
+ if (FD_ISSET(tm->new_fd, &rd)) {
+ if ((c = read(tm->new_fd, tm->buff2+tm->buff2_avail,
+ BUFSIZE-tm->buff2_avail)) <= 0) break;
+ c = handle_iacs(tm, c, tm->pty_fd);
+ tm->buff2_avail += c;
+ if ((w = write(tm->pty_fd, tm->buff2+ tm->buff2_written,
+ tm->buff2_avail - tm->buff2_written)) < 0) break;
+ tm->buff2_written += w;
+ }
+ if (FD_ISSET(tm->pty_fd, &wr)) {
+ if ((w = write(tm->pty_fd, tm->buff2 + tm->buff2_written,
+ tm->buff2_avail - tm->buff2_written)) < 0) break;
+ tm->buff2_written += w;
+ }
+ if (FD_ISSET(tm->new_fd, &wr)) {
+ if ((w = dup_iacs(tm->buff1 + tm->buff1_written, tm->new_fd + inetd_m,
+ tm->buff1_avail - tm->buff1_written)) < 0) break;
+ tm->buff1_written += w;
+ }
+ if (tm->buff1_written == tm->buff1_avail)
+ tm->buff1_written = tm->buff1_avail = 0;
+ if (tm->buff2_written == tm->buff2_avail)
+ tm->buff2_written = tm->buff2_avail = 0;
+ fflush(NULL);
+ }
+ if (TT.sig) kill_session();
+ }
+}
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