--- /dev/null
+/* vi: set sw=4 ts=4: */
+/*
+ * A fake identd server
+ *
+ * Adapted to busybox by Thomas Lundquist <thomasez@zelow.no>
+ * Original Author: Tomi Ollila <too@iki.fi>
+ * http://www.guru-group.fi/~too/sw/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <string.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <sys/syslog.h>
+
+#include <pwd.h>
+#include <netdb.h>
+
+#include <sys/syslog.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <time.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <errno.h>
+#include <arpa/inet.h>
+#include <sys/uio.h>
+
+#include "busybox.h"
+
+#define IDENT_PORT 113
+#define MAXCONNS 20
+#define MAXIDLETIME 45
+
+static const char ident_substr[] = " : USERID : UNIX : ";
+static const int ident_substr_len = sizeof(ident_substr) - 1;
+#define PIDFILE "/var/run/identd.pid"
+
+/*
+ * We have to track the 'first connection socket' so that we
+ * don't go around closing file descriptors for non-clients.
+ *
+ * descriptor setup normally
+ * 0 = server socket
+ * 1 = syslog fd (hopefully -- otherwise this won't work)
+ * 2 = connection socket after detached from tty. standard error before that
+ * 3 - 2 + MAXCONNS = rest connection sockets
+ *
+ * To try to make sure that syslog fd is what is "requested", the that fd
+ * is closed before openlog() call. It can only severely fail if fd 0
+ * is initially closed.
+ */
+#define FCS 2
+
+/*
+ * FD of the connection is always the index of the connection structure
+ * in `conns' array + FCS
+ */
+struct {
+ char buf[20];
+ int len;
+ time_t lasttime;
+} conns[MAXCONNS];
+
+/* When using global variables, bind those at least to a structure. */
+struct {
+ const char *identuser;
+ fd_set readfds;
+ int conncnt;
+} G;
+
+/*
+ * Prototypes
+ */
+static void reply(int s, char *buf);
+static void replyError(int s, char *buf);
+
+static const char *nobodystr = "nobody"; /* this needs to be declared like this */
+static char *bind_ip_address = "0.0.0.0";
+
+static inline void movefd(int from, int to)
+{
+ if (from != to) {
+ dup2(from, to);
+ close(from);
+ }
+}
+
+static void inetbind(void)
+{
+ int s, port;
+ struct sockaddr_in addr;
+ int len = sizeof(addr);
+ int one = 1;
+ struct servent *se;
+
+ if ((se = getservbyname("identd", "tcp")) == NULL)
+ port = IDENT_PORT;
+ else
+ port = se->s_port;
+
+ if ((s = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+ bb_perror_msg_and_die("Cannot create server socket");
+
+ setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
+
+ memset(&addr, 0, sizeof(addr));
+ addr.sin_addr.s_addr = inet_addr(bind_ip_address);
+ addr.sin_family = AF_INET;
+ addr.sin_port = htons(port);
+
+ if (bind(s, (struct sockaddr *)&addr, len) < 0)
+ bb_perror_msg_and_die("Cannot bind() port %i", IDENT_PORT);
+
+ if (listen(s, 5) < 0)
+ bb_perror_msg_and_die("Cannot listen() on port %i", IDENT_PORT);
+
+ movefd(s, 0);
+}
+
+static void delpidfile(void)
+{
+ /*
+ * Usually nobody has no write/delete access to directory /var/run/
+ * therefore if file cannot be deleted, it is truncated
+ */
+ if (unlink(PIDFILE) < 0)
+ close(open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0644));
+}
+
+static void handlexitsigs(int signum)
+{
+ delpidfile();
+ exit(0);
+}
+
+/* May succeed. If not, won't care. */
+static void writepid(uid_t nobody, uid_t nogrp)
+{
+ char buf[24];
+ int fd = open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0664);
+
+ if (fd < 0)
+ return;
+
+ snprintf(buf, 23, "%d\n", getpid());
+ write(fd, buf, strlen(buf));
+ fchown(fd, nobody, nogrp);
+ close(fd);
+
+ /* should this handle ILL, ... (see signal(7)) */
+ signal(SIGTERM, handlexitsigs);
+ signal(SIGINT, handlexitsigs);
+ signal(SIGQUIT, handlexitsigs);
+}
+
+/* return 0 as parent, 1 as child */
+static int godaemon(void)
+{
+ uid_t nobody, nogrp;
+ struct passwd *pw;
+
+ switch (fork()) {
+ case -1:
+ bb_perror_msg_and_die("Could not fork");
+
+ case 0:
+ pw = getpwnam(nobodystr);
+ if (pw == NULL)
+ bb_error_msg_and_die("Cannot find uid/gid of user '%s'", nobodystr);
+ nobody = pw->pw_uid;
+ nogrp = pw->pw_gid;
+ writepid(nobody, nogrp);
+
+ close(0);
+ inetbind();
+ if (setgid(nogrp)) bb_error_msg_and_die("Could not setgid()");
+ if (setegid(nogrp)) bb_error_msg_and_die("Could not setegid()");
+ if (setuid(nobody)) bb_error_msg_and_die("Could not setuid()");
+ if (seteuid(nobody)) bb_error_msg_and_die("Could not seteuid()");
+ close(1);
+ close(2);
+
+ signal(SIGHUP, SIG_IGN);
+ signal(SIGPIPE, SIG_IGN); /* connection closed when writing (raises ???) */
+
+ setsid();
+
+ openlog(bb_applet_name, 0, LOG_DAEMON);
+ return 1;
+ }
+
+ return 0;
+}
+
+static void deleteConn(int s)
+{
+ int i = s - FCS;
+
+ close(s);
+
+ G.conncnt--;
+
+ /*
+ * Most of the time there is 0 connections. Most often that there
+ * is connections, there is just one connection. When this one connection
+ * closes, i == G.conncnt = 0 -> no copying.
+ * When there is more than one connection, the oldest connections closes
+ * earlier on average. When this happens, the code below starts copying
+ * the connection structure w/ highest index to the place which which is
+ * just deleted. This means that the connection structures are no longer
+ * in chronological order. I'd quess this means that when there is more
+ * than 1 connection, on average every other connection structure needs
+ * to be copied over the time all these connections are deleted.
+ */
+ if (i != G.conncnt) {
+ memcpy(&conns[i], &conns[G.conncnt], sizeof(conns[0]));
+ movefd(G.conncnt + FCS, s);
+ }
+
+ FD_CLR(G.conncnt + FCS, &G.readfds);
+}
+
+static int closeOldest(void)
+{
+ time_t min = conns[0].lasttime;
+ int idx = 0;
+ int i;
+
+ for (i = 1; i < MAXCONNS; i++)
+ if (conns[i].lasttime < min)
+ idx = i;
+
+ replyError(idx + FCS, "X-SERVER-TOO-BUSY");
+ close(idx + FCS);
+
+ return idx;
+}
+
+static int checkInput(char *buf, int len, int l)
+{
+ int i;
+ for (i = len; i < len + l; ++i)
+ if (buf[i] == '\n')
+ return 1;
+ return 0;
+}
+
+int fakeidentd_main(int argc, char **argv)
+{
+ int flag;
+
+ memset(conns, 0, sizeof(conns));
+ memset(&G, 0, sizeof(G));
+ FD_ZERO(&G.readfds);
+ FD_SET(0, &G.readfds);
+
+ /* handle -b <ip> parameter */
+ while ((flag = getopt(argc, argv, "b:")) != EOF) {
+ switch (flag) {
+ case 'b':
+ bind_ip_address = optarg;
+ break;
+ default:
+ bb_show_usage();
+ }
+ }
+ /* handle optional REPLY STRING */
+ if (optind < argc)
+ G.identuser = argv[optind];
+ else
+ G.identuser = nobodystr;
+
+ /* daemonize and have the parent return */
+ if (godaemon() == 0)
+ return 0;
+
+ while (1) {
+ fd_set rfds = G.readfds;
+ struct timeval tv = { 15, 0 };
+ int i;
+ int tim = time(NULL);
+
+ select(G.conncnt + FCS, &rfds, NULL, NULL, G.conncnt? &tv: NULL);
+
+ for (i = G.conncnt - 1; i >= 0; i--) {
+ int s = i + FCS;
+
+ if (FD_ISSET(s, &rfds)) {
+ char *buf = conns[i].buf;
+ unsigned int len = conns[i].len;
+ unsigned int l;
+
+ if ((l = read(s, buf + len, sizeof(conns[0].buf) - len)) > 0) {
+ if (checkInput(buf, len, l)) {
+ reply(s, buf);
+ goto deleteconn;
+ } else if (len + l >= sizeof(conns[0].buf)) {
+ replyError(s, "X-INVALID-REQUEST");
+ goto deleteconn;
+ } else {
+ conns[i].len += l;
+ }
+ } else {
+ goto deleteconn;
+ }
+
+ conns[i].lasttime = tim;
+ continue;
+
+deleteconn:
+ deleteConn(s);
+ } else {
+ /* implement as time_after() in linux kernel sources ... */
+ if (conns[i].lasttime + MAXIDLETIME <= tim) {
+ replyError(s, "X-TIMEOUT");
+ deleteConn(s);
+ }
+ }
+ }
+
+ if (FD_ISSET(0, &rfds)) {
+ int s = accept(0, NULL, 0);
+
+ if (s < 0) {
+ if (errno != EINTR) /* EINTR */
+ syslog(LOG_ERR, "accept: %s", strerror(errno));
+ } else {
+ if (G.conncnt == MAXCONNS)
+ i = closeOldest();
+ else
+ i = G.conncnt++;
+
+ movefd(s, i + FCS); /* move if not already there */
+ FD_SET(i + FCS, &G.readfds);
+
+ conns[i].len = 0;
+ conns[i].lasttime = time(NULL);
+ }
+ }
+ } /* end of while(1) */
+
+ return 0;
+}
+
+static int parseAddrs(char *ptr, char **myaddr, char **heraddr);
+static void reply(int s, char *buf)
+{
+ char *myaddr, *heraddr;
+
+ myaddr = heraddr = NULL;
+
+ if (parseAddrs(buf, &myaddr, &heraddr))
+ replyError(s, "X-INVALID-REQUEST");
+ else {
+ struct iovec iv[6];
+ iv[0].iov_base = myaddr; iv[0].iov_len = strlen(myaddr);
+ iv[1].iov_base = ", "; iv[1].iov_len = 2;
+ iv[2].iov_base = heraddr; iv[2].iov_len = strlen(heraddr);
+ iv[3].iov_base = (void *)ident_substr; iv[3].iov_len = ident_substr_len;
+ iv[4].iov_base = (void *)G.identuser; iv[4].iov_len = strlen(G.identuser);
+ iv[5].iov_base = "\r\n"; iv[5].iov_len = 2;
+ writev(s, iv, 6);
+ }
+}
+
+static void replyError(int s, char *buf)
+{
+ struct iovec iv[3];
+ iv[0].iov_base = "0, 0 : ERROR : "; iv[0].iov_len = 15;
+ iv[1].iov_base = buf; iv[1].iov_len = strlen(buf);
+ iv[2].iov_base = "\r\n"; iv[2].iov_len = 2;
+ writev(s, iv, 3);
+}
+
+static int chmatch(char c, char *chars)
+{
+ for (; *chars; chars++)
+ if (c == *chars)
+ return 1;
+ return 0;
+}
+
+static int skipchars(char **p, char *chars)
+{
+ while (chmatch(**p, chars))
+ (*p)++;
+ if (**p == '\r' || **p == '\n')
+ return 0;
+ return 1;
+}
+
+static int parseAddrs(char *ptr, char **myaddr, char **heraddr)
+{
+ /* parse <port-on-server> , <port-on-client> */
+
+ if (!skipchars(&ptr, " \t"))
+ return -1;
+
+ *myaddr = ptr;
+
+ if (!skipchars(&ptr, "1234567890"))
+ return -1;
+
+ if (!chmatch(*ptr, " \t,"))
+ return -1;
+
+ *ptr++ = '\0';
+
+ if (!skipchars(&ptr, " \t,") )
+ return -1;
+
+ *heraddr = ptr;
+
+ skipchars(&ptr, "1234567890");
+
+ if (!chmatch(*ptr, " \n\r"))
+ return -1;
+
+ *ptr = '\0';
+
+ return 0;
+}
projects / oweals / busybox.git / commitdiff