Add two new options for lpd: -c will log all connection-errors to syslog,
while -w allows connection from non-reserved ports. Also improves the helpfulness of various connection-error messages. The changes for IPv6 added back in the reserved-port check which was mistakenly dropped from lpd in 1997 (copying a change from openbsd). It is best to have that check in place, but the check breaks lpr's from some implementations of lpr/lpd for Windows. The -w option is for those admins who need to accept jobs from non-reserved ports, the -c option is for admins who would like a print-server machine to log all failed connection-attempts to syslog. Reviewed by: freebsd-audit@FreeBSD.org freebsd-print@bostonradio.org MFC after: 2 weeks
This commit is contained in:
Garance A Drosehn
parent
2b47b55f69
commit
6ddb63cad6
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=78749
@ -32,7 +32,7 @@
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.\" @(#)lpd.8 8.3 (Berkeley) 4/19/94
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.\" $FreeBSD$
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.\"
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.Dd April 19, 1994
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.Dd June 06, 2001
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.Dt LPD 8
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.Os BSD 4.2
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.Sh NAME
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@ -40,7 +40,7 @@
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.Nd line printer spooler daemon
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.Sh SYNOPSIS
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.Nm
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.Op Fl dlp46
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.Op Fl cdlpw46
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.Op Ar port#
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.Sh DESCRIPTION
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.Nm Lpd
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@ -62,6 +62,19 @@ the request so the parent can continue to listen for more requests.
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.Pp
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Available options:
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.Bl -tag -width Ds
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.It Fl c
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By default, if some remote host has a connection error while trying to
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send a print request to
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.Nm
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on a local host,
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.Nm
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will only send error message to that remote host.
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The
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.Fl c
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flag causes
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.Nm
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to also log all of those connection errors via
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.Xr syslog 3 .
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.It Fl d
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Turn on
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.Dv SO_DEBUG
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@ -81,6 +94,23 @@ The
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flag causes
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.Nm
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not to open an Internet listening socket.
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This means that
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.Nm
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will not accept any connections from any remote
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hosts, although it will still accept print requests
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from all local users.
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.It Fl w
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By default, the
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.Nm
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daemon will only accept connections which originate
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from a reserved-port (<1024) on the remote host.
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The
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.Fl w
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flag causes
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.Nm
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to accept connections coming from any port.
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This is can be useful when you want to accept print jobs
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from certain implementations of lpr written for Windows.
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.It Fl 4
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Inet only.
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.It Fl 6
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@ -112,8 +112,10 @@ static void reapchild(int _signo);
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static void mcleanup(int _signo);
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static void doit(void);
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static void startup(void);
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static void chkhost(struct sockaddr *_f);
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static void chkhost(struct sockaddr *_f, int _ch_opts);
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static int ckqueue(struct printer *_pp);
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static void fhosterr(int _dosys, const char *_sysmsg, const char *_usermsg,
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...);
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static int *socksetup(int _af, int _debuglvl);
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static void usage(void);
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@ -123,10 +125,13 @@ extern int __ivaliduser_sa __P((FILE *, struct sockaddr *, socklen_t,
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uid_t uid, euid;
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#define LPD_NOPORTCHK 0001 /* skip reserved-port check */
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#define LPD_LOGCONNERR 0002 /* (sys)log connection errors */
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int
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main(int argc, char **argv)
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{
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int errs, f, funix, *finet, fromlen, i, options, socket_debug;
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int ch_options, errs, f, funix, *finet, fromlen, i, socket_debug;
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fd_set defreadfds;
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struct sockaddr_un un, fromunix;
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struct sockaddr_storage frominet;
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@ -137,6 +142,8 @@ main(int argc, char **argv)
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euid = geteuid(); /* these shouldn't be different */
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uid = getuid();
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ch_options = 0;
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socket_debug = 0;
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gethostname(local_host, sizeof(local_host));
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@ -146,8 +153,12 @@ main(int argc, char **argv)
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errx(EX_NOPERM,"must run as root");
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errs = 0;
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while ((i = getopt(argc, argv, "dlp46")) != -1)
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while ((i = getopt(argc, argv, "cdlpw46")) != -1)
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switch (i) {
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case 'c':
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/* log all kinds of connection-errors to syslog */
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ch_options |= LPD_LOGCONNERR;
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break;
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case 'd':
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socket_debug++;
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break;
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@ -157,6 +168,11 @@ main(int argc, char **argv)
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case 'p':
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pflag++;
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break;
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case 'w':
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/* allow connections coming from a non-reserved port */
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/* (done by some lpr-implementations for MS-Windows) */
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ch_options |= LPD_NOPORTCHK;
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break;
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case '4':
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family = PF_INET;
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inet_flag++;
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@ -366,7 +382,8 @@ main(int argc, char **argv)
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if (domain == AF_INET) {
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/* for both AF_INET and AF_INET6 */
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from_remote = 1;
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chkhost((struct sockaddr *)&frominet);
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chkhost((struct sockaddr *)&frominet,
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ch_options);
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} else
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from_remote = 0;
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doit();
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@ -600,36 +617,40 @@ ckqueue(struct printer *pp)
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#define DUMMY ":nobody::"
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/*
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* Check to see if the from host has access to the line printer.
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* Check to see if the host connecting to this host has access to any
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* lpd services on this host.
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*/
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static void
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chkhost(struct sockaddr *f)
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chkhost(struct sockaddr *f, int ch_opts)
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{
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struct addrinfo hints, *res, *r;
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register FILE *hostf;
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int first = 1;
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int good = 0;
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char hostbuf[NI_MAXHOST], ip[NI_MAXHOST];
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char serv[NI_MAXSERV];
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int error, addrlen;
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caddr_t addr;
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int error, errsav, fpass, good, wantsl;
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error = getnameinfo(f, f->sa_len, NULL, 0, serv, sizeof(serv),
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NI_NUMERICSERV);
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if (error || atoi(serv) >= IPPORT_RESERVED)
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fatal(0, "Malformed from address");
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wantsl = 0;
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if (ch_opts & LPD_LOGCONNERR)
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wantsl = 1; /* also syslog the errors */
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from_host = ".na.";
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/* Need real hostname for temporary filenames */
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error = getnameinfo(f, f->sa_len, hostbuf, sizeof(hostbuf), NULL, 0,
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NI_NAMEREQD);
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if (error) {
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errsav = error;
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error = getnameinfo(f, f->sa_len, hostbuf, sizeof(hostbuf),
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NULL, 0, NI_NUMERICHOST | NI_WITHSCOPEID);
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if (error)
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fatal(0, "Host name for your address unknown");
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fhosterr(wantsl,
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"can not determine hostname for remote host (%d)",
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"Host name for your address not known", error);
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else
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fatal(0, "Host name for your address (%s) unknown",
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hostbuf);
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fhosterr(wantsl,
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"Host name for remote host (%s) not known (%d)",
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"Host name for your address (%s) not known",
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hostbuf, errsav);
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}
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strlcpy(frombuf, hostbuf, sizeof(frombuf));
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@ -639,7 +660,8 @@ chkhost(struct sockaddr *f)
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error = getnameinfo(f, f->sa_len, hostbuf, sizeof(hostbuf), NULL, 0,
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NI_NUMERICHOST | NI_WITHSCOPEID);
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if (error)
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fatal(0, "Cannot print address");
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fhosterr(wantsl, "Cannot print IP address (error %d)",
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"Cannot print IP address", error);
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from_ip = strdup(hostbuf);
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/* Reject numeric addresses */
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@ -649,7 +671,8 @@ chkhost(struct sockaddr *f)
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hints.ai_flags = AI_PASSIVE | AI_NUMERICHOST;
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if (getaddrinfo(from_host, NULL, &hints, &res) == 0) {
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freeaddrinfo(res);
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fatal(0, "reverse lookup results in non-FQDN %s", from_host);
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fhosterr(wantsl, NULL, "reverse lookup results in non-FQDN %s",
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from_host);
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}
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/* Check for spoof, ala rlogind */
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@ -658,38 +681,121 @@ chkhost(struct sockaddr *f)
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hints.ai_socktype = SOCK_DGRAM; /*dummy*/
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error = getaddrinfo(from_host, NULL, &hints, &res);
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if (error) {
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fatal(0, "hostname for your address (%s) unknown: %s", from_ip,
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gai_strerror(error));
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fhosterr(wantsl, "dns lookup for address %s failed: %s",
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"hostname for your address (%s) unknown: %s", from_ip,
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gai_strerror(error));
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}
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good = 0;
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for (r = res; good == 0 && r; r = r->ai_next) {
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error = getnameinfo(r->ai_addr, r->ai_addrlen, ip, sizeof(ip),
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NULL, 0, NI_NUMERICHOST | NI_WITHSCOPEID);
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NULL, 0, NI_NUMERICHOST | NI_WITHSCOPEID);
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if (!error && !strcmp(from_ip, ip))
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good = 1;
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}
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if (res)
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freeaddrinfo(res);
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if (good == 0)
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fatal(0, "address for your hostname (%s) not matched",
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from_ip);
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fhosterr(wantsl, "address for remote host (%s) not matched",
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"address for your hostname (%s) not matched", from_ip);
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fpass = 1;
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hostf = fopen(_PATH_HOSTSEQUIV, "r");
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again:
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if (hostf) {
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if (__ivaliduser_sa(hostf, f, f->sa_len, DUMMY, DUMMY) == 0) {
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(void) fclose(hostf);
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return;
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goto foundhost;
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}
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(void) fclose(hostf);
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}
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if (first == 1) {
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first = 0;
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if (fpass == 1) {
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fpass = 2;
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hostf = fopen(_PATH_HOSTSLPD, "r");
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goto again;
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}
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fatal(0, "Your host does not have line printer access");
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fhosterr(wantsl, "refused connection from %s, sip=%s",
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"Print-services are not available to your host (%s).", from_host,
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from_ip);
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/*NOTREACHED*/
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foundhost:
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if (ch_opts & LPD_NOPORTCHK)
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return; /* skip the reserved-port check */
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error = getnameinfo(f, f->sa_len, NULL, 0, serv, sizeof(serv),
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NI_NUMERICSERV);
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if (error)
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fhosterr(wantsl, NULL, "malformed from-address (%d)", error);
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if (atoi(serv) >= IPPORT_RESERVED)
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fhosterr(wantsl, NULL, "connected from invalid port (%s)",
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serv);
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}
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#include <stdarg.h>
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/*
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* Handle fatal errors in chkhost. The first message will optionally be sent
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* to syslog, the second one is sent to the connecting host. If the first
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* message is NULL, then the same message is used for both. Note that the
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* argument list for both messages are assumed to be the same (or at least
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* the initial arguments for one must be EXACTLY the same as the complete
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* argument list for the other message).
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*
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* The idea is that the syslog message is meant for an administrator of a
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* print server (the host receiving connections), while the usermsg is meant
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* for a remote user who may or may not be clueful, and may or may not be
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* doing something nefarious. Some remote users (eg, MS-Windows...) may not
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* even see whatever message is sent, which is why there's the option to
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* start 'lpd' with the connection-errors also sent to syslog.
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*
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* Given that hostnames can theoretically be fairly long (well, over 250
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* bytes), it would probably be helpful to have the 'from_host' field at
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* the end of any error messages which include that info.
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*/
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void
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fhosterr(int dosys, const char *sysmsg, const char *usermsg, ...)
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{
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va_list ap;
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char *sbuf, *ubuf;
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const char *testone;
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va_start(ap, usermsg);
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vasprintf(&ubuf, usermsg, ap);
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va_end(ap);
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if (dosys) {
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sbuf = ubuf; /* assume sysmsg == NULL */
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if (sysmsg != NULL) {
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va_start(ap, usermsg);
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vasprintf(&sbuf, sysmsg, ap);
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va_end(ap);
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}
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/*
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* If the first variable-parameter is not the 'from_host',
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* then first write THAT information as a line to syslog.
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*/
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va_start(ap, usermsg);
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testone = va_arg(ap, const char *);
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if (testone != from_host) {
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syslog(LOG_WARNING, "for connection from %s:", from_host);
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}
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va_end(ap);
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/* now write the syslog message */
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syslog(LOG_WARNING, "%s", sbuf);
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}
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printf("%s [@%s]: %s\n", progname, local_host, ubuf);
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fflush(stdout);
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/*
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* Add a minimal delay before exiting (and disconnecting from the
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* sending-host). This is just in case that machine responds by
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* INSTANTLY retrying (and instantly re-failing...). This may also
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* give the other side more time to read the error message.
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*/
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sleep(2); /* a paranoid throttling measure */
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exit(1);
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}
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/* setup server socket for specified address family */
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@ -777,9 +883,9 @@ static void
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usage(void)
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{
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#ifdef INET6
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fprintf(stderr, "usage: lpd [-dlp46] [port#]\n");
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fprintf(stderr, "usage: lpd [-cdlpw46] [port#]\n");
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#else
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fprintf(stderr, "usage: lpd [-dlp] [port#]\n");
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fprintf(stderr, "usage: lpd [-cdlpw] [port#]\n");
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#endif
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exit(EX_USAGE);
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}
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