import fakeidentd module started by Thomas Lundquist
This commit is contained in:
Mike Frysinger
parent
77dbe738d2
commit
fa69f110d9
@ -185,6 +185,9 @@
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#ifdef CONFIG_EXPR
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APPLET(expr, expr_main, _BB_DIR_USR_BIN, _BB_SUID_NEVER)
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#endif
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#ifdef CONFIG_FAKEIDENTD
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APPLET(fakeidentd, fakeidentd_main, _BB_DIR_USR_SBIN, _BB_SUID_NEVER)
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#endif
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#ifdef CONFIG_FALSE
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APPLET(false, false_main, _BB_DIR_BIN, _BB_SUID_NEVER)
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#endif
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@ -575,6 +575,13 @@
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"\\( and \\) or null; if \\( and \\) are not used, they return the number \n" \
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"of characters matched or 0."
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#define fakeidentd_trivial_usage \
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"[-b ip] [STRING]"
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#define fakeidentd_full_usage \
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"Returns a set string to auth requests\n\n"\
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"\t-b\tBind to ip address\n"\
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"\tSTRING\tThe ident answer string (default is nobody)"
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#define false_trivial_usage \
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""
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#define false_full_usage \
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@ -18,6 +18,13 @@ config CONFIG_ARPING
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help
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Ping hosts by ARP packets
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config CONFIG_FAKEIDENTD
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bool "fakeidentd"
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default n
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help
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fakeidentd listens to the ident port and returns a set fake
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value whatever it gets.
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config CONFIG_FTPGET
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bool "ftpget"
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default n
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@ -24,6 +24,7 @@ endif
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srcdir=$(top_srcdir)/networking
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NETWORKING-y:=
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NETWORKING-$(CONFIG_ARPING) += arping.o
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NETWORKING-$(CONFIG_FAKEIDENTD) += fakeidentd.o
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NETWORKING-$(CONFIG_FTPGET) += ftpgetput.o
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NETWORKING-$(CONFIG_FTPPUT) += ftpgetput.o
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NETWORKING-$(CONFIG_HOSTNAME) += hostname.o
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441
networking/fakeidentd.c
Normal file
441
networking/fakeidentd.c
Normal file
@ -0,0 +1,441 @@
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/* vi: set sw=4 ts=4: */
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/*
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* A fake identd server
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*
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* Adapted to busybox by Thomas Lundquist <thomasez@zelow.no>
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* Original Author: Tomi Ollila <too@iki.fi>
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* http://www.guru-group.fi/~too/sw/
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <string.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <sys/syslog.h>
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#include <pwd.h>
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#include <netdb.h>
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#include <sys/syslog.h>
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#include <sys/types.h>
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#include <sys/time.h>
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#include <time.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <errno.h>
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#include <arpa/inet.h>
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#include <sys/uio.h>
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#include "busybox.h"
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#define IDENT_PORT 113
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#define MAXCONNS 20
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#define MAXIDLETIME 45
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static const char ident_substr[] = " : USERID : UNIX : ";
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static const int ident_substr_len = sizeof(ident_substr) - 1;
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#define PIDFILE "/var/run/identd.pid"
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/*
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* We have to track the 'first connection socket' so that we
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* don't go around closing file descriptors for non-clients.
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*
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* descriptor setup normally
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* 0 = server socket
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* 1 = syslog fd (hopefully -- otherwise this won't work)
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* 2 = connection socket after detached from tty. standard error before that
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* 3 - 2 + MAXCONNS = rest connection sockets
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*
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* To try to make sure that syslog fd is what is "requested", the that fd
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* is closed before openlog() call. It can only severely fail if fd 0
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* is initially closed.
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*/
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#define FCS 2
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/*
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* FD of the connection is always the index of the connection structure
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* in `conns' array + FCS
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*/
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struct {
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char buf[20];
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int len;
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time_t lasttime;
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} conns[MAXCONNS];
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/* When using global variables, bind those at least to a structure. */
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struct {
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const char *identuser;
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fd_set readfds;
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int conncnt;
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} G;
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/*
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* Prototypes
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*/
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static void reply(int s, char *buf);
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static void replyError(int s, char *buf);
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static const char *nobodystr = "nobody"; /* this needs to be declared like this */
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static char *bind_ip_address = "0.0.0.0";
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static inline void movefd(int from, int to)
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{
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if (from != to) {
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dup2(from, to);
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close(from);
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}
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}
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static void inetbind(void)
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{
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int s, port;
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struct sockaddr_in addr;
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int len = sizeof(addr);
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int one = 1;
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struct servent *se;
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if ((se = getservbyname("identd", "tcp")) == NULL)
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port = IDENT_PORT;
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else
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port = se->s_port;
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if ((s = socket(AF_INET, SOCK_STREAM, 0)) < 0)
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bb_perror_msg_and_die("Cannot create server socket");
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setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
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memset(&addr, 0, sizeof(addr));
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addr.sin_addr.s_addr = inet_addr(bind_ip_address);
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addr.sin_family = AF_INET;
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addr.sin_port = htons(port);
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if (bind(s, (struct sockaddr *)&addr, len) < 0)
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bb_perror_msg_and_die("Cannot bind() port %i", IDENT_PORT);
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if (listen(s, 5) < 0)
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bb_perror_msg_and_die("Cannot listen() on port %i", IDENT_PORT);
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movefd(s, 0);
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}
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static void delpidfile(void)
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{
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/*
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* Usually nobody has no write/delete access to directory /var/run/
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* therefore if file cannot be deleted, it is truncated
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*/
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if (unlink(PIDFILE) < 0)
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close(open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0644));
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}
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static void handlexitsigs(int signum)
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{
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delpidfile();
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exit(0);
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}
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/* May succeed. If not, won't care. */
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static void writepid(uid_t nobody, uid_t nogrp)
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{
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char buf[24];
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int fd = open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0664);
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if (fd < 0)
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return;
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snprintf(buf, 23, "%d\n", getpid());
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write(fd, buf, strlen(buf));
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fchown(fd, nobody, nogrp);
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close(fd);
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/* should this handle ILL, ... (see signal(7)) */
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signal(SIGTERM, handlexitsigs);
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signal(SIGINT, handlexitsigs);
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signal(SIGQUIT, handlexitsigs);
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}
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/* return 0 as parent, 1 as child */
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static int godaemon(void)
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{
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uid_t nobody, nogrp;
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struct passwd *pw;
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switch (fork()) {
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case -1:
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bb_perror_msg_and_die("Could not fork");
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case 0:
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pw = getpwnam(nobodystr);
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if (pw == NULL)
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bb_error_msg_and_die("Cannot find uid/gid of user '%s'", nobodystr);
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nobody = pw->pw_uid;
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nogrp = pw->pw_gid;
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writepid(nobody, nogrp);
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close(0);
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inetbind();
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if (setgid(nogrp)) bb_error_msg_and_die("Could not setgid()");
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if (setegid(nogrp)) bb_error_msg_and_die("Could not setegid()");
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if (setuid(nobody)) bb_error_msg_and_die("Could not setuid()");
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if (seteuid(nobody)) bb_error_msg_and_die("Could not seteuid()");
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close(1);
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close(2);
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signal(SIGHUP, SIG_IGN);
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signal(SIGPIPE, SIG_IGN); /* connection closed when writing (raises ???) */
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setsid();
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openlog(bb_applet_name, 0, LOG_DAEMON);
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return 1;
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}
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return 0;
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}
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static void deleteConn(int s)
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{
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int i = s - FCS;
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close(s);
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G.conncnt--;
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/*
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* Most of the time there is 0 connections. Most often that there
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* is connections, there is just one connection. When this one connection
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* closes, i == G.conncnt = 0 -> no copying.
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* When there is more than one connection, the oldest connections closes
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* earlier on average. When this happens, the code below starts copying
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* the connection structure w/ highest index to the place which which is
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* just deleted. This means that the connection structures are no longer
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* in chronological order. I'd quess this means that when there is more
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* than 1 connection, on average every other connection structure needs
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* to be copied over the time all these connections are deleted.
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*/
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if (i != G.conncnt) {
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memcpy(&conns[i], &conns[G.conncnt], sizeof(conns[0]));
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movefd(G.conncnt + FCS, s);
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}
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FD_CLR(G.conncnt + FCS, &G.readfds);
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}
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static int closeOldest(void)
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{
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time_t min = conns[0].lasttime;
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int idx = 0;
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int i;
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for (i = 1; i < MAXCONNS; i++)
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if (conns[i].lasttime < min)
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idx = i;
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replyError(idx + FCS, "X-SERVER-TOO-BUSY");
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close(idx + FCS);
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return idx;
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}
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static int checkInput(char *buf, int len, int l)
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{
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int i;
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for (i = len; i < len + l; ++i)
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if (buf[i] == '\n')
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return 1;
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return 0;
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}
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int fakeidentd_main(int argc, char **argv)
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{
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int flag;
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memset(conns, 0, sizeof(conns));
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memset(&G, 0, sizeof(G));
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FD_ZERO(&G.readfds);
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FD_SET(0, &G.readfds);
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/* handle -b <ip> parameter */
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while ((flag = getopt(argc, argv, "b:")) != EOF) {
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switch (flag) {
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case 'b':
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bind_ip_address = optarg;
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break;
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default:
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bb_show_usage();
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}
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}
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/* handle optional REPLY STRING */
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if (optind < argc)
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G.identuser = argv[optind];
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else
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G.identuser = nobodystr;
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/* daemonize and have the parent return */
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if (godaemon() == 0)
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return 0;
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while (1) {
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fd_set rfds = G.readfds;
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struct timeval tv = { 15, 0 };
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int i;
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int tim = time(NULL);
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select(G.conncnt + FCS, &rfds, NULL, NULL, G.conncnt? &tv: NULL);
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for (i = G.conncnt - 1; i >= 0; i--) {
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int s = i + FCS;
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if (FD_ISSET(s, &rfds)) {
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char *buf = conns[i].buf;
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unsigned int len = conns[i].len;
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unsigned int l;
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if ((l = read(s, buf + len, sizeof(conns[0].buf) - len)) > 0) {
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if (checkInput(buf, len, l)) {
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reply(s, buf);
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goto deleteconn;
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} else if (len + l >= sizeof(conns[0].buf)) {
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replyError(s, "X-INVALID-REQUEST");
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goto deleteconn;
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} else {
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conns[i].len += l;
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}
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} else {
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goto deleteconn;
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}
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conns[i].lasttime = tim;
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continue;
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deleteconn:
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deleteConn(s);
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} else {
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/* implement as time_after() in linux kernel sources ... */
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if (conns[i].lasttime + MAXIDLETIME <= tim) {
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replyError(s, "X-TIMEOUT");
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deleteConn(s);
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}
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}
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}
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if (FD_ISSET(0, &rfds)) {
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int s = accept(0, NULL, 0);
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if (s < 0) {
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if (errno != EINTR) /* EINTR */
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syslog(LOG_ERR, "accept: %s", strerror(errno));
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} else {
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if (G.conncnt == MAXCONNS)
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i = closeOldest();
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else
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i = G.conncnt++;
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movefd(s, i + FCS); /* move if not already there */
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FD_SET(i + FCS, &G.readfds);
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conns[i].len = 0;
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conns[i].lasttime = time(NULL);
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}
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}
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} /* end of while(1) */
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return 0;
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}
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static int parseAddrs(char *ptr, char **myaddr, char **heraddr);
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static void reply(int s, char *buf)
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{
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char *myaddr, *heraddr;
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myaddr = heraddr = NULL;
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if (parseAddrs(buf, &myaddr, &heraddr))
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replyError(s, "X-INVALID-REQUEST");
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else {
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struct iovec iv[6];
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iv[0].iov_base = myaddr; iv[0].iov_len = strlen(myaddr);
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iv[1].iov_base = ", "; iv[1].iov_len = 2;
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iv[2].iov_base = heraddr; iv[2].iov_len = strlen(heraddr);
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iv[3].iov_base = (void *)ident_substr; iv[3].iov_len = ident_substr_len;
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iv[4].iov_base = (void *)G.identuser; iv[4].iov_len = strlen(G.identuser);
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iv[5].iov_base = "\r\n"; iv[5].iov_len = 2;
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writev(s, iv, 6);
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}
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}
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static void replyError(int s, char *buf)
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{
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struct iovec iv[3];
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iv[0].iov_base = "0, 0 : ERROR : "; iv[0].iov_len = 15;
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iv[1].iov_base = buf; iv[1].iov_len = strlen(buf);
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iv[2].iov_base = "\r\n"; iv[2].iov_len = 2;
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writev(s, iv, 3);
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}
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static int chmatch(char c, char *chars)
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{
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for (; *chars; chars++)
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if (c == *chars)
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return 1;
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return 0;
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}
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static int skipchars(char **p, char *chars)
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{
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while (chmatch(**p, chars))
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(*p)++;
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if (**p == '\r' || **p == '\n')
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return 0;
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return 1;
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}
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static int parseAddrs(char *ptr, char **myaddr, char **heraddr)
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{
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/* parse <port-on-server> , <port-on-client> */
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if (!skipchars(&ptr, " \t"))
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return -1;
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*myaddr = ptr;
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if (!skipchars(&ptr, "1234567890"))
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return -1;
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if (!chmatch(*ptr, " \t,"))
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return -1;
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*ptr++ = '\0';
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if (!skipchars(&ptr, " \t,") )
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return -1;
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*heraddr = ptr;
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skipchars(&ptr, "1234567890");
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if (!chmatch(*ptr, " \n\r"))
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return -1;
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*ptr = '\0';
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return 0;
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}
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