Imported Upstream version 1.18.2upstream/1.18.2

1 files changed, 242 insertions, 0 deletions

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+/* net.c
+ * Implementation of network-related stuff.
+ *
+ * File begun on 2007-07-20 by RGerhards (extracted from syslogd.c)
+ * This file is under development and has not yet arrived at being fully
+ * self-contained and a real object. So far, it is mostly an excerpt
+ * of the "old" message code without any modifications. However, it
+ * helps to have things at the right place one we go to the meat of it.
+ *
+ * Copyright 2007 Rainer Gerhards and Adiscon GmbH.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ *
+ * A copy of the GPL can be found in the file "COPYING" in this distribution.
+ */
+#include "config.h"
+
+#ifdef SYSLOG_INET
+
+#include "rsyslog.h"
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+#include <signal.h>
+#include <ctype.h>
+#include <netdb.h>
+
+#include "syslogd.h"
+#include "syslogd-types.h"
+#include "net.h"
+
+/* The following #ifdef sequence is a small compatibility 
+ * layer. It tries to work around the different availality
+ * levels of SO_BSDCOMPAT on linuxes...
+ * I borrowed this code from
+ *    http://www.erlang.org/ml-archive/erlang-questions/200307/msg00037.html
+ * It still needs to be a bit better adapted to rsyslog.
+ * rgerhards 2005-09-19
+ */
+#ifndef BSD
+#include <sys/utsname.h>
+int should_use_so_bsdcompat(void)
+{
+    static int init_done;
+    static int so_bsdcompat_is_obsolete;
+
+    if (!init_done) {
+	struct utsname utsname;
+	unsigned int version, patchlevel;
+
+	init_done = 1;
+	if (uname(&utsname) < 0) {
+	    dbgprintf("uname: %s\r\n", strerror(errno));
+	    return 1;
+	}
+	/* Format is <version>.<patchlevel>.<sublevel><extraversion>
+	   where the first three are unsigned integers and the last
+	   is an arbitrary string. We only care about the first two. */
+	if (sscanf(utsname.release, "%u.%u", &version, &patchlevel) != 2) {
+	    dbgprintf("uname: unexpected release '%s'\r\n",
+		    utsname.release);
+	    return 1;
+	}
+	/* SO_BSCOMPAT is deprecated and triggers warnings in 2.5
+	   kernels. It is a no-op in 2.4 but not in 2.2 kernels. */
+	if (version > 2 || (version == 2 && patchlevel >= 5))
+	    so_bsdcompat_is_obsolete = 1;
+    }
+    return !so_bsdcompat_is_obsolete;
+}
+#else	/* #ifndef BSD */
+#define should_use_so_bsdcompat() 1
+#endif	/* #ifndef BSD */
+#ifndef SO_BSDCOMPAT
+/* this shall prevent compiler errors due to undfined name */
+#define SO_BSDCOMPAT 0
+#endif
+
+
+/* Return a printable representation of a host address.
+ * Now (2007-07-16) also returns the full host name (if it could be obtained)
+ * in the second param [thanks to mildew@gmail.com for the patch].
+ * The caller must provide buffer space for pszHost and pszHostFQDN. These
+ * buffers must be of size NI_MAXHOST. This is not checked here, because
+ * there is no way to check it. We use this way of doing things because it
+ * frees us from using dynamic memory allocation where it really does not
+ * pay.
+ * Please see http://www.hmug.org/man/3/getnameinfo.php (under Caveats)
+ * for some explanation of the code found below. We do by default not
+ * discard message where we detected malicouos DNS PTR records. However,
+ * there is a user-configurabel option that will tell us if
+ * we should abort. For this, the return value tells the caller if the
+ * message should be processed (1) or discarded (0).
+ */
+int cvthname(struct sockaddr_storage *f, uchar *pszHost, uchar *pszHostFQDN)
+{
+	register uchar *p;
+	int count, error;
+	sigset_t omask, nmask;
+	char ip[NI_MAXHOST];
+	struct addrinfo hints, *res;
+	
+	assert(f != NULL);
+	assert(pszHost != NULL);
+	assert(pszHostFQDN != NULL);
+
+        error = getnameinfo((struct sockaddr *)f, SALEN((struct sockaddr *)f),
+			    ip, sizeof ip, NULL, 0, NI_NUMERICHOST);
+
+        if (error) {
+                dbgprintf("Malformed from address %s\n", gai_strerror(error));
+		strcpy((char*) pszHost, "???");
+		strcpy((char*) pszHostFQDN, "???");
+		return 1;
+	}
+
+	if (!DisableDNS) {
+		sigemptyset(&nmask);
+		sigaddset(&nmask, SIGHUP);
+		sigprocmask(SIG_BLOCK, &nmask, &omask);
+
+		error = getnameinfo((struct sockaddr *)f, sizeof(*f),
+				    (char*)pszHostFQDN, NI_MAXHOST, NULL, 0, NI_NAMEREQD);
+		
+		if (error == 0) {
+			memset (&hints, 0, sizeof (struct addrinfo));
+			hints.ai_flags = AI_NUMERICHOST;
+			hints.ai_socktype = SOCK_DGRAM;
+
+			/* we now do a lookup once again. This one should fail,
+			 * because we should not have obtained a numeric address. If
+			 * we got a numeric one, someone messed with DNS!
+			 */
+			if (getaddrinfo ((char*)pszHostFQDN, NULL, &hints, &res) == 0) {
+				uchar szErrMsg[1024];
+				freeaddrinfo (res);
+				/* OK, we know we have evil. The question now is what to do about
+				 * it. One the one hand, the message might probably be intended
+				 * to harm us. On the other hand, losing the message may also harm us.
+				 * Thus, the behaviour is controlled by the $DropMsgsWithMaliciousDnsPTRRecords
+				 * option. If it tells us we should discard, we do so, else we proceed,
+				 * but log an error message together with it.
+				 * time being, we simply drop the name we obtained and use the IP - that one
+				 * is OK in any way. We do also log the error message. rgerhards, 2007-07-16
+		 		 */
+		 		if(bDropMalPTRMsgs == 1) {
+					snprintf((char*)szErrMsg, sizeof(szErrMsg) / sizeof(uchar),
+						 "Malicious PTR record, message dropped "
+						 "IP = \"%s\" HOST = \"%s\"",
+						 ip, pszHostFQDN);
+					logerror((char*)szErrMsg);
+					return 0;
+				}
+
+				/* Please note: we deal with a malicous entry. Thus, we have crafted
+				 * the snprintf() below so that all text is in front of the entry - maybe
+				 * it would contain characters that would make the message unreadble
+				 * (OK, I admit this is more or less impossible, but I am paranoid...)
+				 * rgerhards, 2007-07-16
+				 */
+				snprintf((char*)szErrMsg, sizeof(szErrMsg) / sizeof(uchar),
+					 "Malicious PTR record (message accepted, but used IP "
+					 "instead of PTR name: IP = \"%s\" HOST = \"%s\"",
+					 ip, pszHostFQDN);
+				logerror((char*)szErrMsg);
+
+				error = 1; /* that will trigger using IP address below. */
+			}
+		}		
+		sigprocmask(SIG_SETMASK, &omask, NULL);
+	}
+
+        if (error || DisableDNS) {
+                dbgprintf("Host name for your address (%s) unknown\n", ip);
+		strcpy((char*) pszHostFQDN, ip);
+		strcpy((char*) pszHost, ip);
+		return 1;
+        }
+
+	/* Convert to lower case, just like LocalDomain above
+	 */
+	for (p = pszHostFQDN ; *p ; p++)
+		if (isupper((int) *p))
+			*p = tolower(*p);
+	
+	/* OK, the fqdn is now known. Now it is time to extract only the hostname
+	 * part if we were instructed to do so.
+	 */
+	/* TODO: quick and dirty right now: we need to optimize that. We simply
+	 * copy over the buffer and then use the old code.
+	 */
+	strcpy((char*)pszHost, (char*)pszHostFQDN);
+	if ((p = (uchar*) strchr((char*)pszHost, '.'))) {
+		if(strcmp((char*) (p + 1), LocalDomain) == 0) {
+			*p = '\0'; /* simply terminate the string */
+			return 1;
+		} else {
+			if (StripDomains) {
+				count=0;
+				while (StripDomains[count]) {
+					if (strcmp((char*)(p + 1), StripDomains[count]) == 0) {
+						*p = '\0';
+						return 1;
+					}
+					count++;
+				}
+			}
+			/* TODO: bug in syslogd? That all doesn't make so much sense... rger 2007-07-16 */
+			if (LocalHosts) {
+				count=0;
+				while (LocalHosts[count]) {
+					if (!strcmp((char*)pszHost, LocalHosts[count])) {
+						*p = '\0';
+						return 1;
+					}
+					count++;
+				}
+			}
+		}
+	}
+	return 1;
+}
+
+#endif /* #ifdef SYSLOG_INET */
+/*
+ * vi:set ai:
+ */