NetBSD/libexec/identd/identd.c

1046 lines
24 KiB
C

/* $NetBSD: identd.c,v 1.29 2005/06/14 12:17:13 peter Exp $ */
/*
* identd.c - TCP/IP Ident protocol server.
*
* This software is in the public domain.
* Written by Peter Postma <peter@NetBSD.org>
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: identd.c,v 1.29 2005/06/14 12:17:13 peter Exp $");
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <netinet/in.h>
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <netdb.h>
#include <poll.h>
#include <pwd.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include "identd.h"
#define OPSYS_NAME "UNIX"
#define IDENT_SERVICE "auth"
#define TIMEOUT 30 /* seconds */
static int idhandle(int, const char *, const char *, const char *,
const char *, struct sockaddr *, int);
static void idparse(int, int, int, const char *, const char *, const char *);
static void iderror(int, int, int, const char *);
static const char *gethost(struct sockaddr *);
static int *socketsetup(const char *, const char *, int);
static int ident_getuid(struct sockaddr_storage *, socklen_t,
struct sockaddr *, uid_t *);
static int sysctl_getuid(struct sockaddr_storage *, socklen_t, uid_t *);
static int sysctl_proxy_getuid(struct sockaddr_storage *,
struct sockaddr *, uid_t *);
static int forward(int, struct sockaddr *, int, int, int);
static int check_noident(const char *);
static int check_userident(const char *, char *, size_t);
static void random_string(char *, size_t);
static int change_format(const char *, struct passwd *, char *, size_t);
static void timeout_handler(int);
static void fatal(const char *);
static void die(const char *, ...);
static int bflag, eflag, fflag, iflag, Iflag;
static int lflag, Lflag, nflag, Nflag, rflag;
/* NAT lookup function pointer. */
static int (*nat_lookup)(struct sockaddr_storage *, struct sockaddr *, int *);
/* Packet filters. */
static const struct {
const char *name;
int (*fn)(struct sockaddr_storage *, struct sockaddr *, int *);
} filters[] = {
#ifdef WITH_PF
{ "pf", pf_natlookup },
#endif
#ifdef WITH_IPF
{ "ipfilter", ipf_natlookup },
#endif
{ NULL, NULL }
};
int
main(int argc, char *argv[])
{
int IPv4or6, ch, error, i, *socks, timeout;
const char *filter, *osname, *portno, *proxy;
char *address, *charset, *fmt, *p;
char user[LOGIN_NAME_MAX];
struct addrinfo *ai, hints;
struct sockaddr *proxy_addr;
struct group *grp;
struct passwd *pw;
gid_t gid;
uid_t uid;
socks = NULL;
IPv4or6 = AF_UNSPEC;
osname = OPSYS_NAME;
portno = IDENT_SERVICE;
timeout = TIMEOUT;
nat_lookup = NULL;
proxy_addr = NULL;
filter = proxy = NULL;
address = charset = fmt = NULL;
uid = gid = 0;
bflag = eflag = fflag = iflag = Iflag = 0;
lflag = Lflag = nflag = Nflag = rflag = 0;
/* Started from a tty? then run as daemon. */
if (isatty(STDIN_FILENO))
bflag = 1;
/* Parse command line arguments. */
while ((ch = getopt(argc, argv,
"46a:bceF:f:g:IiL:lm:Nno:P:p:rt:u:")) != -1) {
switch (ch) {
case '4':
IPv4or6 = AF_INET;
break;
case '6':
IPv4or6 = AF_INET6;
break;
case 'a':
address = optarg;
break;
case 'b':
bflag = 1;
break;
case 'c':
charset = optarg;
break;
case 'e':
eflag = 1;
break;
case 'F':
fmt = optarg;
break;
case 'f':
fflag = 1;
(void)strlcpy(user, optarg, sizeof(user));
break;
case 'g':
gid = (gid_t)strtol(optarg, &p, 0);
if (*p != '\0') {
if ((grp = getgrnam(optarg)) != NULL)
gid = grp->gr_gid;
else
die("No such group `%s'", optarg);
}
break;
case 'I':
Iflag = 1;
/* FALLTHROUGH */
case 'i':
iflag = 1;
break;
case 'L':
Lflag = 1;
(void)strlcpy(user, optarg, sizeof(user));
break;
case 'l':
if (!lflag)
openlog("identd", LOG_PID, LOG_DAEMON);
lflag = 1;
break;
case 'm':
filter = optarg;
break;
case 'N':
Nflag = 1;
break;
case 'n':
nflag = 1;
break;
case 'o':
osname = optarg;
break;
case 'P':
proxy = optarg;
break;
case 'p':
portno = optarg;
break;
case 'r':
rflag = 1;
break;
case 't':
timeout = (int)strtol(optarg, &p, 0);
if (*p != '\0' || timeout < 1)
die("Invalid timeout value `%s'", optarg);
break;
case 'u':
uid = (uid_t)strtol(optarg, &p, 0);
if (*p != '\0') {
if ((pw = getpwnam(optarg)) != NULL) {
uid = pw->pw_uid;
gid = pw->pw_gid;
} else
die("No such user `%s'", optarg);
}
break;
default:
exit(EXIT_FAILURE);
}
}
/* Verify proxy address, if enabled. */
if (proxy != NULL) {
(void)memset(&hints, 0, sizeof(hints));
hints.ai_family = IPv4or6;
hints.ai_socktype = SOCK_STREAM;
error = getaddrinfo(proxy, NULL, &hints, &ai);
if (error != 0)
die("Bad proxy `%s': %s", proxy, gai_strerror(error));
if (ai->ai_next != NULL)
die("Bad proxy `%s': resolves to multiple addresses",
proxy);
proxy_addr = ai->ai_addr;
}
/* Verify filter, if enabled. */
if (filter != NULL) {
for (i = 0; filters[i].name != NULL; i++) {
if (strcasecmp(filter, filters[i].name) == 0) {
nat_lookup = filters[i].fn;
break;
}
}
if (nat_lookup == NULL)
die("Packet filter `%s' is not supported", filter);
}
/* Setup sockets when running in the background. */
if (bflag)
socks = socketsetup(address, portno, IPv4or6);
/* Switch to another uid/gid? */
if (gid && setgid(gid) == -1)
die("Failed to set GID to `%d': %s", gid, strerror(errno));
if (uid && setuid(uid) == -1)
die("Failed to set UID to `%d': %s", uid, strerror(errno));
/*
* When running as daemon: daemonize, setup pollfds and go into
* the mainloop. Otherwise, just read the input from stdin and
* let inetd handle the sockets.
*/
if (bflag) {
int fd, nfds, rv;
struct pollfd *rfds;
if (daemon(0, 0) < 0)
die("daemon: %s", strerror(errno));
rfds = malloc(*socks * sizeof(struct pollfd));
if (rfds == NULL)
fatal("malloc");
nfds = *socks;
for (i = 0; i < nfds; i++) {
rfds[i].fd = socks[i+1];
rfds[i].events = POLLIN;
rfds[i].revents = 0;
}
/* Mainloop for daemon. */
for (;;) {
rv = poll(rfds, nfds, INFTIM);
if (rv < 0) {
if (errno == EINTR)
continue;
fatal("poll");
}
for (i = 0; i < nfds; i++) {
if (rfds[i].revents & POLLIN) {
fd = accept(rfds[i].fd, NULL, NULL);
if (fd < 0) {
maybe_syslog(LOG_ERR,
"accept: %m");
continue;
}
switch (fork()) {
case -1: /* error */
maybe_syslog(LOG_ERR,
"fork: %m");
(void)sleep(1);
break;
case 0: /* child */
(void)idhandle(fd, charset,
fmt, osname, user,
proxy_addr, timeout);
_exit(EXIT_SUCCESS);
default: /* parent */
(void)signal(SIGCHLD, SIG_IGN);
(void)close(fd);
}
}
}
}
} else
(void)idhandle(STDIN_FILENO, charset, fmt, osname, user,
proxy_addr, timeout);
return 0;
}
/*
* Handle a request on the ident port. Returns 0 on success or 1 on
* failure. The return values are currently ignored.
*/
static int
idhandle(int fd, const char *charset, const char *fmt, const char *osname,
const char *user, struct sockaddr *proxy, int timeout)
{
struct sockaddr_storage ss[2];
char userbuf[LOGIN_NAME_MAX]; /* actual user name (or numeric uid) */
char idbuf[LOGIN_NAME_MAX]; /* name to be used in response */
char buf[BUFSIZ], *p;
struct passwd *pw;
int lport, fport;
socklen_t len;
uid_t uid;
ssize_t n;
lport = fport = 0;
(void)strlcpy(idbuf, user, sizeof(idbuf));
(void)signal(SIGALRM, timeout_handler);
(void)alarm(timeout);
/* Get foreign internet address. */
len = sizeof(ss[0]);
if (getpeername(fd, (struct sockaddr *)&ss[0], &len) < 0)
fatal("getpeername");
maybe_syslog(LOG_INFO, "Connection from %s",
gethost((struct sockaddr *)&ss[0]));
/* Get local internet address. */
len = sizeof(ss[1]);
if (getsockname(fd, (struct sockaddr *)&ss[1], &len) < 0)
fatal("getsockname");
/* Be sure to have the same address families. */
if (ss[0].ss_family != ss[1].ss_family) {
maybe_syslog(LOG_ERR, "Different foreign/local address family");
return 1;
}
/* Receive data from the client. */
if ((n = recv(fd, buf, sizeof(buf) - 1, 0)) < 0) {
fatal("recv");
} else if (n == 0) {
maybe_syslog(LOG_NOTICE, "recv: EOF");
iderror(fd, 0, 0, "UNKNOWN-ERROR");
return 1;
}
buf[n] = '\0';
/* Get local and remote ports from the received data. */
p = buf;
while (*p != '\0' && isspace((unsigned char)*p))
p++;
if ((p = strtok(p, " \t,")) != NULL) {
lport = atoi(p);
if ((p = strtok(NULL, " \t,")) != NULL)
fport = atoi(p);
}
/* Are the ports valid? */
if (lport < 1 || lport > 65535 || fport < 1 || fport > 65535) {
maybe_syslog(LOG_NOTICE, "Invalid port(s): %d, %d from %s",
lport, fport, gethost((struct sockaddr *)&ss[0]));
iderror(fd, 0, 0, eflag ? "UNKNOWN-ERROR" : "INVALID-PORT");
return 1;
}
/* If there is a 'lie' user enabled, then handle it now and stop. */
if (Lflag) {
maybe_syslog(LOG_NOTICE, "Lying with name %s to %s",
idbuf, gethost((struct sockaddr *)&ss[0]));
idparse(fd, lport, fport, charset, osname, idbuf);
return 0;
}
/* Protocol dependent stuff. */
switch (ss[0].ss_family) {
case AF_INET:
satosin(&ss[0])->sin_port = htons(fport);
satosin(&ss[1])->sin_port = htons(lport);
break;
case AF_INET6:
satosin6(&ss[0])->sin6_port = htons(fport);
satosin6(&ss[1])->sin6_port = htons(lport);
break;
default:
maybe_syslog(LOG_ERR, "Unsupported protocol (no. %d)",
ss[0].ss_family);
return 1;
}
/* Try to get the UID of the connection owner using sysctl. */
if (ident_getuid(ss, sizeof(ss), proxy, &uid) == -1) {
/* Lookup failed, try to forward if enabled. */
if (nat_lookup != NULL) {
struct sockaddr nat_addr;
int nat_lport;
(void)memset(&nat_addr, 0, sizeof(nat_addr));
if ((*nat_lookup)(ss, &nat_addr, &nat_lport) &&
forward(fd, &nat_addr, nat_lport, fport, lport)) {
maybe_syslog(LOG_INFO,
"Succesfully forwarded the request to %s",
gethost(&nat_addr));
return 0;
}
}
/* Fall back to a default name? */
if (fflag) {
maybe_syslog(LOG_NOTICE, "Using fallback name %s to %s",
idbuf, gethost((struct sockaddr *)&ss[0]));
idparse(fd, lport, fport, charset, osname, idbuf);
return 0;
}
maybe_syslog(LOG_ERR, "Lookup failed, returning error to %s",
gethost((struct sockaddr *)&ss[0]));
iderror(fd, lport, fport, eflag ? "UNKNOWN-ERROR" : "NO-USER");
return 1;
}
/* Fill in userbuf with user name if possible, else numeric UID. */
if ((pw = getpwuid(uid)) == NULL) {
maybe_syslog(LOG_ERR, "Couldn't map uid (%u) to name", uid);
(void)snprintf(userbuf, sizeof(userbuf), "%u", uid);
} else {
maybe_syslog(LOG_INFO, "Successful lookup: %d, %d: %s for %s",
lport, fport, pw->pw_name,
gethost((struct sockaddr *)&ss[0]));
(void)strlcpy(userbuf, pw->pw_name, sizeof(userbuf));
}
/* No ident enabled? */
if (Nflag && pw && check_noident(pw->pw_dir)) {
maybe_syslog(LOG_NOTICE, "Returning HIDDEN-USER for user %s"
" to %s", pw->pw_name, gethost((struct sockaddr *)&ss[0]));
iderror(fd, lport, fport, "HIDDEN-USER");
return 1;
}
/* User ident enabled? */
if (iflag && pw && check_userident(pw->pw_dir, idbuf, sizeof(idbuf))) {
if (!Iflag) {
if ((strspn(idbuf, "0123456789") &&
getpwuid(atoi(idbuf)) != NULL) ||
(getpwnam(idbuf) != NULL)) {
maybe_syslog(LOG_NOTICE,
"Ignoring user-specified '%s' for user %s",
idbuf, userbuf);
(void)strlcpy(idbuf, userbuf, sizeof(idbuf));
}
}
maybe_syslog(LOG_NOTICE,
"Returning user-specified '%s' for user %s to %s",
idbuf, userbuf, gethost((struct sockaddr *)&ss[0]));
idparse(fd, lport, fport, charset, osname, idbuf);
return 0;
}
/* Send a random message? */
if (rflag) {
/* Random number or string? */
if (nflag)
(void)snprintf(idbuf, sizeof(idbuf), "%u",
(unsigned int)(arc4random() % 65535));
else
random_string(idbuf, sizeof(idbuf));
maybe_syslog(LOG_NOTICE,
"Returning random '%s' for user %s to %s",
idbuf, userbuf, gethost((struct sockaddr *)&ss[0]));
idparse(fd, lport, fport, charset, osname, idbuf);
return 0;
}
/* Return numberic user ID? */
if (nflag)
(void)snprintf(idbuf, sizeof(idbuf), "%u", uid);
else
(void)strlcpy(idbuf, userbuf, sizeof(idbuf));
/*
* Change the output format? Note that 512 is the maximum
* size of the result according to RFC 1413.
*/
if (fmt && change_format(fmt, pw, buf, 512 + 1))
idparse(fd, lport, fport, charset, osname, buf);
else
idparse(fd, lport, fport, charset, osname, idbuf);
return 0;
}
/* Send/parse the ident result. */
static void
idparse(int fd, int lport, int fport, const char *charset, const char *osname,
const char *user)
{
char *p;
if (asprintf(&p, "%d,%d:USERID:%s%s%s:%s\r\n", lport, fport,
osname, charset ? "," : "", charset ? charset : "", user) < 0)
fatal("asprintf");
if (send(fd, p, strlen(p), 0) < 0) {
free(p);
fatal("send");
}
free(p);
}
/* Return a specified ident error. */
static void
iderror(int fd, int lport, int fport, const char *error)
{
char *p;
if (asprintf(&p, "%d,%d:ERROR:%s\r\n", lport, fport, error) < 0)
fatal("asprintf");
if (send(fd, p, strlen(p), 0) < 0) {
free(p);
fatal("send");
}
free(p);
}
/* Return the IP address of the connecting host. */
static const char *
gethost(struct sockaddr *sa)
{
static char host[NI_MAXHOST];
if (getnameinfo(sa, sa->sa_len, host, sizeof(host),
NULL, 0, NI_NUMERICHOST) == 0)
return host;
return "UNKNOWN";
}
/* Setup sockets, for daemon mode. */
static int *
socketsetup(const char *address, const char *port, int af)
{
struct addrinfo hints, *res, *res0;
int error, maxs, *s, *socks;
const char *cause = NULL;
socklen_t y = 1;
(void)memset(&hints, 0, sizeof(hints));
hints.ai_flags = AI_PASSIVE;
hints.ai_family = af;
hints.ai_socktype = SOCK_STREAM;
error = getaddrinfo(address, port, &hints, &res0);
if (error) {
die("getaddrinfo: %s", gai_strerror(error));
/* NOTREACHED */
}
/* Count max number of sockets we may open. */
for (maxs = 0, res = res0; res != NULL; res = res->ai_next)
maxs++;
socks = malloc((maxs + 1) * sizeof(int));
if (socks == NULL) {
die("malloc: %s", strerror(errno));
/* NOTREACHED */
}
*socks = 0;
s = socks + 1;
for (res = res0; res != NULL; res = res->ai_next) {
*s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
if (*s < 0) {
cause = "socket";
continue;
}
(void)setsockopt(*s, SOL_SOCKET, SO_REUSEADDR, &y, sizeof(y));
if (bind(*s, res->ai_addr, res->ai_addrlen) < 0) {
cause = "bind";
(void)close(*s);
continue;
}
if (listen(*s, 5) < 0) {
cause = "listen";
(void)close(*s);
continue;
}
*socks = *socks + 1;
s++;
}
if (*socks == 0) {
free(socks);
die("%s: %s", cause, strerror(errno));
/* NOTREACHED */
}
if (res0)
freeaddrinfo(res0);
return socks;
}
/* UID lookup wrapper. */
static int
ident_getuid(struct sockaddr_storage *ss, socklen_t len,
struct sockaddr *proxy, uid_t *uid)
{
int rc;
rc = sysctl_getuid(ss, len, uid);
if (rc == -1 && proxy != NULL)
rc = sysctl_proxy_getuid(ss, proxy, uid);
return rc;
}
/* Try to get the UID of the connection owner using sysctl. */
static int
sysctl_getuid(struct sockaddr_storage *ss, socklen_t len, uid_t *uid)
{
int mib[4];
uid_t myuid;
size_t uidlen;
uidlen = sizeof(myuid);
mib[0] = CTL_NET;
mib[1] = ss->ss_family;
mib[2] = IPPROTO_TCP;
mib[3] = TCPCTL_IDENT;
if (sysctl(mib, sizeof(mib)/ sizeof(int), &myuid, &uidlen, ss, len) < 0)
return -1;
*uid = myuid;
return 0;
}
/* Try to get the UID of the connection owner using sysctl (proxy version). */
static int
sysctl_proxy_getuid(struct sockaddr_storage *ss, struct sockaddr *proxy,
uid_t *uid)
{
struct sockaddr_storage new[2];
int i, rc, name[CTL_MAXNAME];
struct kinfo_pcb *kp;
size_t sz, len;
const char *list;
rc = -1;
sz = CTL_MAXNAME;
list = NULL;
/* Retrieve a list of sockets. */
switch (ss[0].ss_family) {
case AF_INET:
/* We only accept queries from the proxy. */
if (in_hosteq(satosin(&ss[0])->sin_addr,
satosin(proxy)->sin_addr))
list = "net.inet.tcp.pcblist";
break;
case AF_INET6:
/* We only accept queries from the proxy. */
if (IN6_ARE_ADDR_EQUAL(&satosin6(&ss[0])->sin6_addr,
&satosin6(proxy)->sin6_addr))
list = "net.inet6.tcp.pcblist";
break;
default:
maybe_syslog(LOG_ERR, "Unsupported protocol for proxy (no. %d)",
ss[0].ss_family);
}
if (list != NULL)
rc = sysctlnametomib(list, &name[0], &sz);
if (rc == -1)
return -1;
len = sz;
name[len++] = PCB_ALL;
name[len++] = 0;
name[len++] = sizeof(struct kinfo_pcb);
name[len++] = INT_MAX;
kp = NULL;
sz = 0;
do {
rc = sysctl(&name[0], len, kp, &sz, NULL, 0);
if (rc == -1 && errno != ENOMEM)
return -1;
if (kp == NULL) {
kp = malloc(sz);
rc = -1;
}
if (kp == NULL)
return -1;
} while (rc == -1);
rc = -1;
/*
* Walk through the list of sockets and try to find a match.
* We don't know who has sent the query (we only know that the
* proxy has forwarded to us) so just try to match the ports and
* the local address.
*/
for (i = 0; i < sz / sizeof(struct kinfo_pcb); i++) {
switch (ss[0].ss_family) {
case AF_INET:
/* Foreign and local ports must match. */
if (satosin(&ss[0])->sin_port !=
satosin(&kp[i].ki_src)->sin_port)
continue;
if (satosin(&ss[1])->sin_port !=
satosin(&kp[i].ki_dst)->sin_port)
continue;
/* Foreign address may not match proxy address. */
if (in_hosteq(satosin(proxy)->sin_addr,
satosin(&kp[i].ki_dst)->sin_addr))
continue;
/* Local addresses must match. */
if (!in_hosteq(satosin(&ss[1])->sin_addr,
satosin(&kp[i].ki_src)->sin_addr))
continue;
break;
case AF_INET6:
/* Foreign and local ports must match. */
if (satosin6(&ss[0])->sin6_port !=
satosin6(&kp[i].ki_src)->sin6_port)
continue;
if (satosin6(&ss[1])->sin6_port !=
satosin6(&kp[i].ki_dst)->sin6_port)
continue;
/* Foreign address may not match proxy address. */
if (IN6_ARE_ADDR_EQUAL(&satosin6(proxy)->sin6_addr,
&satosin6(&kp[i].ki_dst)->sin6_addr))
continue;
/* Local addresses must match. */
if (!IN6_ARE_ADDR_EQUAL(&satosin6(&ss[1])->sin6_addr,
&satosin6(&kp[i].ki_src)->sin6_addr))
continue;
break;
}
/*
* We have found the foreign address, copy it to a new
* struct and retrieve the UID of the connection owner.
*/
(void)memcpy(&new[0], &kp[i].ki_dst, kp[i].ki_dst.sa_len);
(void)memcpy(&new[1], &kp[i].ki_src, kp[i].ki_src.sa_len);
rc = sysctl_getuid(new, sizeof(new), uid);
/* Done. */
break;
}
free(kp);
return rc;
}
/* Forward ident queries. Returns 1 when succesful, or zero if not. */
static int
forward(int fd, struct sockaddr *nat_addr, int nat_lport, int fport, int lport)
{
char buf[BUFSIZ], reply[BUFSIZ], *p;
ssize_t n;
int sock;
/* Connect to the NAT host. */
sock = socket(nat_addr->sa_family, SOCK_STREAM, 0);
if (sock < 0) {
maybe_syslog(LOG_ERR, "socket: %m");
return 0;
}
if (connect(sock, nat_addr, nat_addr->sa_len) < 0) {
maybe_syslog(LOG_ERR, "Can't connect to %s: %m",
gethost(nat_addr));
(void)close(sock);
return 0;
}
/*
* Send the ident query to the NAT host, but use as local port
* the port of the NAT host.
*/
(void)snprintf(buf, sizeof(buf), "%d , %d\r\n", nat_lport, fport);
if (send(sock, buf, strlen(buf), 0) < 0) {
maybe_syslog(LOG_ERR, "send: %m");
(void)close(sock);
return 0;
}
/* Read the reply from the NAT host. */
if ((n = recv(sock, reply, sizeof(reply) - 1, 0)) < 0) {
maybe_syslog(LOG_ERR, "recv: %m");
(void)close(sock);
return 0;
} else if (n == 0) {
maybe_syslog(LOG_NOTICE, "recv: EOF");
(void)close(sock);
return 0;
}
reply[n] = '\0';
(void)close(sock);
/* Extract everything after the port specs from the ident reply. */
for (p = reply; *p != '\0' && *p != ':'; p++)
continue;
if (*p == '\0' || *++p == '\0') {
maybe_syslog(LOG_ERR, "Malformed ident reply from %s",
gethost(nat_addr));
return 0;
}
/* Build reply for the requesting host, use the original local port. */
(void)snprintf(buf, sizeof(buf), "%d,%d:%s", lport, fport, p);
/* Send the reply from the NAT host back to the requesting host. */
if (send(fd, buf, strlen(buf), 0) < 0) {
maybe_syslog(LOG_ERR, "send: %m");
return 0;
}
return 1;
}
/* Check if a .noident file exists in the user home directory. */
static int
check_noident(const char *homedir)
{
struct stat sb;
char *path;
int ret;
if (homedir == NULL)
return 0;
if (asprintf(&path, "%s/.noident", homedir) < 0)
return 0;
ret = stat(path, &sb);
free(path);
return (ret == 0);
}
/*
* Check if a .ident file exists in the user home directory and
* return the contents of that file.
*/
static int
check_userident(const char *homedir, char *username, size_t len)
{
struct stat sb;
char *path, *p;
ssize_t n;
int fd;
if (len == 0 || homedir == NULL)
return 0;
if (asprintf(&path, "%s/.ident", homedir) < 0)
return 0;
if ((fd = open(path, O_RDONLY|O_NONBLOCK|O_NOFOLLOW, 0)) < 0) {
free(path);
return 0;
}
if (fstat(fd, &sb) < 0 || !S_ISREG(sb.st_mode)) {
(void)close(fd);
free(path);
return 0;
}
if ((n = read(fd, username, len - 1)) < 1) {
(void)close(fd);
free(path);
return 0;
}
username[n] = '\0';
if ((p = strpbrk(username, "\r\n")) != NULL)
*p = '\0';
(void)close(fd);
free(path);
return 1;
}
/* Generate a random string. */
static void
random_string(char *str, size_t len)
{
static const char chars[] = "abcdefghijklmnopqrstuvwxyz1234567890";
char *p;
if (len == 0)
return;
for (p = str; len > 1; len--)
*p++ = chars[arc4random() % (sizeof(chars) - 1)];
*p = '\0';
}
/* Change the output format. */
static int
change_format(const char *format, struct passwd *pw, char *dest, size_t len)
{
struct group *gr;
const char *cp;
char **gmp;
size_t bp;
if (len == 0 || ((gr = getgrgid(pw->pw_gid)) == NULL))
return 0;
for (bp = 0, cp = format; *cp != '\0' && bp < len - 1; cp++) {
if (*cp != '%') {
dest[bp++] = *cp;
continue;
}
if (*++cp == '\0')
break;
switch (*cp) {
case 'u':
(void)snprintf(&dest[bp], len - bp, "%s", pw->pw_name);
break;
case 'U':
(void)snprintf(&dest[bp], len - bp, "%d", pw->pw_uid);
break;
case 'g':
(void)snprintf(&dest[bp], len - bp, "%s", gr->gr_name);
break;
case 'G':
(void)snprintf(&dest[bp], len - bp, "%d", gr->gr_gid);
break;
case 'l':
(void)snprintf(&dest[bp], len - bp, "%s", gr->gr_name);
bp += strlen(&dest[bp]);
if (bp >= len)
break;
setgrent();
while ((gr = getgrent()) != NULL) {
if (gr->gr_gid == pw->pw_gid)
continue;
for (gmp = gr->gr_mem; *gmp && **gmp; gmp++) {
if (strcmp(*gmp, pw->pw_name) == 0) {
(void)snprintf(&dest[bp],
len - bp, ",%s",
gr->gr_name);
bp += strlen(&dest[bp]);
break;
}
}
if (bp >= len)
break;
}
endgrent();
break;
case 'L':
(void)snprintf(&dest[bp], len - bp, "%u", gr->gr_gid);
bp += strlen(&dest[bp]);
if (bp >= len)
break;
setgrent();
while ((gr = getgrent()) != NULL) {
if (gr->gr_gid == pw->pw_gid)
continue;
for (gmp = gr->gr_mem; *gmp && **gmp; gmp++) {
if (strcmp(*gmp, pw->pw_name) == 0) {
(void)snprintf(&dest[bp],
len - bp, ",%u",
gr->gr_gid);
bp += strlen(&dest[bp]);
break;
}
}
if (bp >= len)
break;
}
endgrent();
break;
default:
dest[bp] = *cp;
dest[bp+1] = '\0';
break;
}
bp += strlen(&dest[bp]);
}
dest[bp] = '\0';
return 1;
}
/* Just exit when we caught SIGALRM. */
static void
timeout_handler(int __unused s)
{
maybe_syslog(LOG_INFO, "Timeout for request, closing connection...");
exit(EXIT_FAILURE);
}
/* Report error message string through syslog and quit. */
static void
fatal(const char *func)
{
maybe_syslog(LOG_ERR, "%s: %m", func);
exit(EXIT_FAILURE);
}
/*
* Report an error through syslog and/or stderr and quit. Only used when
* running identd in the background and when it isn't a daemon yet.
*/
static void
die(const char *message, ...)
{
va_list ap;
va_start(ap, message);
if (bflag)
vwarnx(message, ap);
if (lflag)
vsyslog(LOG_ERR, message, ap);
va_end(ap);
exit(EXIT_FAILURE);
}
/* Log using syslog, but only if enabled with the -l flag. */
void
maybe_syslog(int priority, const char *message, ...)
{
va_list ap;
if (lflag) {
va_start(ap, message);
vsyslog(priority, message, ap);
va_end(ap);
}
}