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fakeinetd: attempted ipv6-ization (and it's done)

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but entire applet can be orders of magnitude smaller
if written as an inetd service.
So did that (#ifdef'ed out entire old version).
inetd version is less than 10% of old one!
function                                             old     new   delta
packed_usage                                       22083   22105     +22
nobodystr                                              4       -      -4
bind_ip_address                                        4       -      -4
ident_substr                                          20       -     -20
chmatch                                               22       -     -22
movefd                                                25       -     -25
skipchars                                             49       -     -49
handlexitsigs                                         51       -     -51
replyError                                            70       -     -70
.rodata                                           158120  158024     -96
deleteConn                                           102       -    -102
G                                                    524     388    -136
conns                                                560       -    -560
fakeidentd_main                                     1457     143   -1314
------------------------------------------------------------------------------
(add/remove: 0/10 grow/shrink: 1/3 up/down: 22/-2453)       Total: -2431 bytes
This commit is contained in:
Denis Vlasenko
2007-01-11 23:26:13 +00:00
parent 4fa5e8b455
commit f8138d1f91
3 changed files with 231 additions and 207 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
include/usage.h
View File

@ -826,6 +826,7 @@
"\\( and \\) or null; if \\( and \\) are not used, they return the number\n" \ "\\( and \\) or null; if \\( and \\) are not used, they return the number\n" \
"of characters matched or 0." "of characters matched or 0."
#if 0 /* bloaty */
#define fakeidentd_trivial_usage \ #define fakeidentd_trivial_usage \
"[-b ip] [STRING]" "[-b ip] [STRING]"
#define fakeidentd_full_usage \ #define fakeidentd_full_usage \
@ -833,6 +834,14 @@
"\n\nOptions:\n" \ "\n\nOptions:\n" \
" -b Bind to ip address\n" \ " -b Bind to ip address\n" \
" STRING The ident answer string (default is nobody)" " STRING The ident answer string (default is nobody)"
#else /* inetd-only */
#define fakeidentd_trivial_usage \
"[username]"
#define fakeidentd_full_usage \
"Return a (faked) ident response.\n" \
"This applet is meant to run from inetd.\n" \
"Optional argument is the username to return (default is 'nobody')."
#endif
#define false_trivial_usage \ #define false_trivial_usage \
"" ""

380
networking/fakeidentd.c
View File

@ -9,12 +9,62 @@
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details. * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/ */
/* Ident crash course
*
* Incoming requests are of form "6191, 23\r\n" - peer asks us
* "which user connected from your port 6191 to my port 23?"
* We should answer:
* "6193, 23 : USERID : UNIX : username\r\n"
* and close the connection.
* We can also reply:
* "6195, 23 : USERID : OTHER[,US-ASCII] : username\r\n"
* "6195, 23 : ERROR : INVALID-PORT/NO-USER/HIDDEN-USER/UNKNOWN-ERROR\r\n"
* but we probably will never want that.
*/
#include "busybox.h" #include "busybox.h"
#define SANE_INETD_ONLY_VERSION
#ifdef SANE_INETD_ONLY_VERSION
int fakeidentd_main(int argc, char **argv)
{
char buf[64];
const char *bogouser = "nobody";
char *cur = buf;
int rem = sizeof(buf)-1;
if (argv[1])
bogouser = argv[1];
alarm(30);
while (1) {
char *p;
int sz = safe_read(0, cur, rem);
if (sz < 0) return 1;
cur[sz] = '\0';
p = strpbrk(cur, "\r\n");
if (p) {
*p = '\0';
break;
}
cur += sz;
rem -= sz;
if (!rem || !sz)
break;
}
printf("%s : USERID : UNIX : %s\r\n", buf, bogouser);
return 0;
}
#else
/* Welcome to the bloaty horrors */
#include <sys/syslog.h> #include <sys/syslog.h>
#include <sys/uio.h> #include <sys/uio.h>
#define IDENT_PORT 113
#define MAXCONNS 20 #define MAXCONNS 20
#define MAXIDLETIME 45 #define MAXIDLETIME 45
@ -43,9 +93,9 @@ enum { ident_substr_len = sizeof(ident_substr) - 1 };
* in `conns' array + FCS * in `conns' array + FCS
*/ */
static struct { static struct {
char buf[20];
int len;
time_t lasttime; time_t lasttime;
int len;
char buf[20];
} conns[MAXCONNS]; } conns[MAXCONNS];
/* When using global variables, bind those at least to a structure. */ /* When using global variables, bind those at least to a structure. */
@ -55,14 +105,85 @@ static struct {
int conncnt; int conncnt;
} G; } G;
/* static char *bind_ip_address;
* 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 int chmatch(char c, char *chars)
static char *bind_ip_address = "0.0.0.0"; {
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;
}
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 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 movefd(int from, int to) static void movefd(int from, int to)
{ {
@ -72,96 +193,6 @@ static void movefd(int from, int to)
} }
} }
static void inetbind(void)
{
int s, port;
struct sockaddr_in addr;
int len = sizeof(addr);
struct servent *se;
se = getservbyname("identd", "tcp");
port = IDENT_PORT;
if (se)
port = se->s_port;
s = xsocket(AF_INET, SOCK_STREAM, 0);
setsockopt_reuseaddr(s);
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);
xbind(s, (struct sockaddr *)&addr, len);
xlisten(s, 5);
movefd(s, 0);
}
static void handlexitsigs(int signum)
{
if (unlink(PIDFILE) < 0)
close(open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0644));
exit(0);
}
/* May succeed. If not, won't care. */
static void writepid(uid_t nobody, uid_t nogrp)
{
char buf[sizeof(int)*3 + 2];
int fd = open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0664);
if (fd < 0)
return;
sprintf(buf, "%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("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();
xsetgid(nogrp);
xsetuid(nobody);
close(1);
close(2);
signal(SIGHUP, SIG_IGN);
signal(SIGPIPE, SIG_IGN); /* connection closed when writing (raises ???) */
setsid();
return 1;
}
return 0;
}
static void deleteConn(int s) static void deleteConn(int s)
{ {
int i = s - FCS; int i = s - FCS;
@ -215,15 +246,32 @@ static int checkInput(char *buf, int len, int l)
return 0; return 0;
} }
/* May succeed. If not, won't care. */
static const char *to_unlink;
static void writepid(void)
{
int fd = open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0664);
if (fd < 0)
return;
to_unlink = PIDFILE;
fdprintf(fd, "%d\n", getpid());
close(fd);
}
static void handlexitsigs(int signum)
{
if (to_unlink)
if (unlink(to_unlink) < 0)
close(open(to_unlink, O_WRONLY|O_CREAT|O_TRUNC, 0644));
exit(0);
}
int fakeidentd_main(int argc, char **argv) int fakeidentd_main(int argc, char **argv)
{ {
/* This applet is an inetd-style daemon */ int fd;
openlog(applet_name, 0, LOG_DAEMON); pid_t pid;
logmode = LOGMODE_SYSLOG;
memset(conns, 0, sizeof(conns)); /* FD_ZERO(&G.readfds); - in bss, already zeroed */
memset(&G, 0, sizeof(G));
FD_ZERO(&G.readfds);
FD_SET(0, &G.readfds); FD_SET(0, &G.readfds);
/* handle -b <ip> parameter */ /* handle -b <ip> parameter */
@ -232,11 +280,30 @@ int fakeidentd_main(int argc, char **argv)
if (optind < argc) if (optind < argc)
G.identuser = argv[optind]; G.identuser = argv[optind];
else else
G.identuser = nobodystr; G.identuser = "nobody";
/* daemonize and have the parent return */ writepid();
if (godaemon() == 0) signal(SIGTERM, handlexitsigs);
return 0; signal(SIGINT, handlexitsigs);
signal(SIGQUIT, handlexitsigs);
signal(SIGHUP, SIG_IGN);
signal(SIGPIPE, SIG_IGN); /* ignore closed connections when writing */
fd = create_and_bind_stream_or_die(bind_ip_address, bb_lookup_port("identd", "tcp", 113));
xlisten(fd, 5);
pid = fork();
if (pid < 0)
bb_perror_msg_and_die("fork");
if (pid != 0) /* parent */
exit(0);
/* child */
setsid();
movefd(fd, 0);
while (fd)
close(fd--);
openlog(applet_name, 0, LOG_DAEMON);
logmode = LOGMODE_SYSLOG;
/* main loop where we process all events and never exit */ /* main loop where we process all events and never exit */
while (1) { while (1) {
@ -252,10 +319,11 @@ int fakeidentd_main(int argc, char **argv)
if (FD_ISSET(s, &rfds)) { if (FD_ISSET(s, &rfds)) {
char *buf = conns[i].buf; char *buf = conns[i].buf;
unsigned int len = conns[i].len; unsigned len = conns[i].len;
unsigned int l; unsigned l;
if ((l = read(s, buf + len, sizeof(conns[0].buf) - len)) > 0) { l = read(s, buf + len, sizeof(conns[0].buf) - len);
if (l > 0) {
if (checkInput(buf, len, l)) { if (checkInput(buf, len, l)) {
reply(s, buf); reply(s, buf);
goto deleteconn; goto deleteconn;
@ -268,10 +336,8 @@ int fakeidentd_main(int argc, char **argv)
} else { } else {
goto deleteconn; goto deleteconn;
} }
conns[i].lasttime = tim; conns[i].lasttime = tim;
continue; continue;
deleteconn: deleteconn:
deleteConn(s); deleteConn(s);
} else { } else {
@ -287,7 +353,7 @@ deleteconn:
int s = accept(0, NULL, 0); int s = accept(0, NULL, 0);
if (s < 0) { if (s < 0) {
if (errno != EINTR) /* EINTR */ if (errno != EINTR)
bb_perror_msg("accept"); bb_perror_msg("accept");
} else { } else {
if (G.conncnt == MAXCONNS) if (G.conncnt == MAXCONNS)
@ -297,7 +363,6 @@ deleteconn:
movefd(s, i + FCS); /* move if not already there */ movefd(s, i + FCS); /* move if not already there */
FD_SET(i + FCS, &G.readfds); FD_SET(i + FCS, &G.readfds);
conns[i].len = 0; conns[i].len = 0;
conns[i].lasttime = time(NULL); conns[i].lasttime = time(NULL);
} }
@ -307,81 +372,4 @@ deleteconn:
return 0; return 0;
} }
static int parseAddrs(char *ptr, char **myaddr, char **heraddr); #endif /* !SANE_INETD_ONLY_VERSION */
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;
}

49
networking/inetd.c
View File

@ -23,7 +23,7 @@
* may be used to endorse or promote products derived from this software * may be used to endorse or promote products derived from this software
* without specific prior written permission. * without specific prior written permission.
* *
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
@ -36,8 +36,7 @@
* SUCH DAMAGE. * SUCH DAMAGE.
*/ */
/* /* Inetd - Internet super-server
* Inetd - Internet super-server
* *
* This program invokes all internet services as needed. * This program invokes all internet services as needed.
* connection-oriented services are invoked each time a * connection-oriented services are invoked each time a
@ -50,14 +49,14 @@
* arrives; a process is created and passed a pending message * arrives; a process is created and passed a pending message
* on file descriptor 0. Datagram servers may either connect * on file descriptor 0. Datagram servers may either connect
* to their peer, freeing up the original socket for inetd * to their peer, freeing up the original socket for inetd
* to receive further messages on, or ``take over the socket'', * to receive further messages on, or "take over the socket",
* processing all arriving datagrams and, eventually, timing * processing all arriving datagrams and, eventually, timing
* out. The first type of server is said to be ``multi-threaded''; * out. The first type of server is said to be "multi-threaded";
* the second type of server ``single-threaded''. * the second type of server "single-threaded".
* *
* Inetd uses a configuration file which is read at startup * Inetd uses a configuration file which is read at startup
* and, possibly, at some later time in response to a hangup signal. * and, possibly, at some later time in response to a hangup signal.
* The configuration file is ``free format'' with fields given in the * The configuration file is "free format" with fields given in the
* order shown below. Continuation lines for an entry must begin with * order shown below. Continuation lines for an entry must begin with
* a space or tab. All fields must be present in each entry. * a space or tab. All fields must be present in each entry.
* *
@ -105,8 +104,37 @@
* Comment lines are indicated by a `#' in column 1. * Comment lines are indicated by a `#' in column 1.
*/ */
/* /* inetd rules for passing file descriptors to children
* Here's the scoop concerning the user[.:]group feature: * (http://www.freebsd.org/cgi/man.cgi?query=inetd):
*
* The wait/nowait entry specifies whether the server that is invoked by
* inetd will take over the socket associated with the service access point,
* and thus whether inetd should wait for the server to exit before listen-
* ing for new service requests. Datagram servers must use "wait", as
* they are always invoked with the original datagram socket bound to the
* specified service address. These servers must read at least one datagram
* from the socket before exiting. If a datagram server connects to its
* peer, freeing the socket so inetd can receive further messages on the
* socket, it is said to be a "multi-threaded" server; it should read one
* datagram from the socket and create a new socket connected to the peer.
* It should fork, and the parent should then exit to allow inetd to check
* for new service requests to spawn new servers. Datagram servers which
* process all incoming datagrams on a socket and eventually time out are
* said to be "single-threaded". The comsat(8), (biff(1)) and talkd(8)
* utilities are both examples of the latter type of datagram server. The
* tftpd(8) utility is an example of a multi-threaded datagram server.
*
* Servers using stream sockets generally are multi-threaded and use the
* "nowait" entry. Connection requests for these services are accepted by
* inetd, and the server is given only the newly-accepted socket connected
* to a client of the service. Most stream-based services operate in this
* manner. Stream-based servers that use "wait" are started with the lis-
* tening service socket, and must accept at least one connection request
* before exiting. Such a server would normally accept and process incoming
* connection requests until a timeout.
*/
/* Here's the scoop concerning the user[.:]group feature:
* *
* 1) set-group-option off. * 1) set-group-option off.
* *
@ -125,7 +153,6 @@
* b) other: setgid(specified group) * b) other: setgid(specified group)
* initgroups(name, specified group) * initgroups(name, specified group)
* setuid() * setuid()
*
*/ */
#include "busybox.h" #include "busybox.h"
@ -161,7 +188,7 @@
#endif #endif
/* Reserve some descriptors, 3 stdio + at least: 1 log, 1 conf. file */ /* Reserve some descriptors, 3 stdio + at least: 1 log, 1 conf. file */
#define FD_MARGIN (8) #define FD_MARGIN 8
static rlim_t rlim_ofile_cur = OPEN_MAX; static rlim_t rlim_ofile_cur = OPEN_MAX;
static struct rlimit rlim_ofile; static struct rlimit rlim_ofile;