import fakeidentd module started by Thomas Lundquist

include/applets.h

@@ -185,6 +185,9 @@
 #ifdef CONFIG_EXPR
 	APPLET(expr, expr_main, _BB_DIR_USR_BIN, _BB_SUID_NEVER)
 #endif
+#ifdef CONFIG_FAKEIDENTD
+	APPLET(fakeidentd, fakeidentd_main, _BB_DIR_USR_SBIN, _BB_SUID_NEVER)
+#endif
 #ifdef CONFIG_FALSE
 	APPLET(false, false_main, _BB_DIR_BIN, _BB_SUID_NEVER)
 #endif

include/usage.h

@@ -575,6 +575,13 @@
 	"\\( and \\) or null; if \\( and \\) are not used, they return the number \n" \
 	"of characters matched or 0."
 
+#define fakeidentd_trivial_usage \
+	"[-b ip] [STRING]"
+#define fakeidentd_full_usage \
+	"Returns a set string to auth requests\n\n"\
+	"\t-b\tBind to ip address\n"\
+	"\tSTRING\tThe ident answer string (default is nobody)"
+
 #define false_trivial_usage \
 	""
 #define false_full_usage \

networking/Config.in

@@ -18,6 +18,13 @@ config CONFIG_ARPING
 	help
 	  Ping hosts by ARP packets
 
+config CONFIG_FAKEIDENTD
+	bool "fakeidentd"
+	default n
+	help
+	  fakeidentd listens to the ident port and returns a set fake 
+	  value whatever it gets.
+
 config CONFIG_FTPGET
 	bool "ftpget"
 	default n

networking/Makefile.in

@@ -24,6 +24,7 @@ endif
 srcdir=$(top_srcdir)/networking
 NETWORKING-y:=
 NETWORKING-$(CONFIG_ARPING)	+= arping.o
+NETWORKING-$(CONFIG_FAKEIDENTD)	+= fakeidentd.o
 NETWORKING-$(CONFIG_FTPGET)	+= ftpgetput.o
 NETWORKING-$(CONFIG_FTPPUT)	+= ftpgetput.o
 NETWORKING-$(CONFIG_HOSTNAME)	+= hostname.o

networking/fakeidentd.c

@@ -0,0 +1,441 @@
+/* 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;
+}