From 9b273d1930cc6ccaada911d77db4c47e019119d2 Mon Sep 17 00:00:00 2001
From: Rainer Gerhards <rgerhards@adiscon.com>
Date: Mon, 30 Sep 2013 11:17:52 +0200
Subject: omfwd: new action parameter "maxErrorMessages" added

---
 ChangeLog         |  1 +
 doc/omfwd.html    | 30 +++++++++++++++++++++---------
 runtime/rsyslog.h |  2 ++
 tools/omfwd.c     | 32 ++++++++++++++++++++++++++------
 4 files changed, 50 insertions(+), 15 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 4f7d6614..dbf15813 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,6 @@
 ---------------------------------------------------------------------------
 Version 7.5.4 [devel] 2013-09-??
+- omfwd: new action parameter "maxErrorMessages" added
 - omfile: new module parameters to set action defaults added
   * dirCreateMode
   * fileCreateMode
diff --git a/doc/omfwd.html b/doc/omfwd.html
index 554c98ac..848ecdd3 100644
--- a/doc/omfwd.html
+++ b/doc/omfwd.html
@@ -20,14 +20,14 @@ If you prefer, you can also
 a specific version of the rsyslog documentation</a>.
 <p>&nbsp;</p>
 
-<p><b>Global Configuration Directives</b>:</p>
+<p><b>Module Parameters</b>:</p>
 <ul>
 	<li><strong>Template </strong>[templateName]<br>
 	sets a non-standard default template for this module.<br></li>
 	
 </ul>
 <p>&nbsp;</p>
-<p><b>Action specific Configuration Directives</b>:</p>
+<p><b>Action Parameters</b>:</p>
 <ul>
 	<li><strong>Target </strong>string<br>
 	Name or IP-Address of the system that shall receive messages. Any resolvable name is fine. <br></li><br>
@@ -50,6 +50,19 @@ a specific version of the rsyslog documentation</a>.
 	compression mode, so pre 7.5.1 configuration will continue to work
 	as expected.
 	<br>The compression level is specified via the usual factor of 0 to 9, with 9 being the strongest compression (taking up most processing time) and 0 being no compression at all (taking up no extra processing time). <br></li><br>
+
+	<li><b>maxErrorMessages </b>integer [default 5], available since 7.5.4<br>
+	This sets the maximum number of error messages that omfwd
+	emits during regular operations. The reason for such an upper
+	limit is that error messages are conveyed back to rsyslog's
+	input message stream. So if there would be no limit, an endless
+	loop could be initiated if the failing action would need to
+	process its own error messages and the emit a new one. This is
+	also the reason why the default is very conservatively low.
+	Note that version prior to 7.5.4 did not report any error
+	messages for the same reason. Also note that with the initial
+	implementation only errors during UDP forwarding are logged.<br></li><br>
+
 	<li><b>compression.mode</b> <i>mode</i><br>
 	<i>mode</i> is one of "none", "single", or "stream:always". The 
 	default is "none", in which no compression happens at all.
@@ -113,12 +126,11 @@ a specific version of the rsyslog documentation</a>.
 <p><b>Caveats/Known Bugs:</b></p><ul><li>None.</li></ul>
 <p><b>Sample:</b></p>
 <p>The following command sends all syslog messages to a remote server via TCP port 10514.</p>
-<textarea rows="5" cols="60">Module (load="builtin:omfwd")
-*.* action(type="omfwd" 
-Target="192.168.2.11"
-Port="10514"
-Protocol="tcp"
-)
+<textarea rows="5" cols="60">action(type="omfwd" 
+       Target="192.168.2.11"
+       Port="10514"
+       Protocol="tcp"
+      )
 </textarea>
 
 <br><br>
@@ -165,7 +177,7 @@ Protocol="tcp"
 index</a>] [<a href="http://www.rsyslog.com/">rsyslog site</a>]</p>
 <p><font size="2">This documentation is part of the
 <a href="http://www.rsyslog.com/">rsyslog</a> project.<br>
-Copyright © 2008 by <a href="http://www.gerhards.net/rainer">Rainer Gerhards</a> and
+Copyright &copy; 2008-2013 by <a href="http://www.gerhards.net/rainer">Rainer Gerhards</a> and
 <a href="http://www.adiscon.com/">Adiscon</a>. Released under the GNU GPL 
 version 3 or higher.</font></p>
 
diff --git a/runtime/rsyslog.h b/runtime/rsyslog.h
index 743296b5..fffcfbf4 100644
--- a/runtime/rsyslog.h
+++ b/runtime/rsyslog.h
@@ -424,6 +424,8 @@ enum rsRetVal_				/** return value. All methods return this if not specified oth
 	RS_RET_QUEUE_CRY_DISK_ONLY = -2351,/**< crypto provider only supported for disk-associated queues */
 	RS_RET_NO_DATA = -2352,/**< file has no data; more a state than a real error */
 	RS_RET_RELP_AUTH_FAIL = -2353,/**< RELP peer authentication failed */
+	RS_RET_ERR_UDPSEND = -2354,/**< sending msg via UDP failed */
+	RS_RET_LAST_ERRREPORT = -2355,/**< module does not emit more error messages as limit is reached */
 
 	/* RainerScript error messages (range 1000.. 1999) */
 	RS_RET_SYSVAR_NOT_FOUND = 1001, /**< system variable could not be found (maybe misspelled) */
diff --git a/tools/omfwd.c b/tools/omfwd.c
index 3c8221c3..6e5cf809 100644
--- a/tools/omfwd.c
+++ b/tools/omfwd.c
@@ -109,6 +109,7 @@ typedef struct _instanceData {
 	z_stream zstrm;	/* zip stream to use for tcp compression */
 	uchar sndBuf[16*1024];	/* this is intensionally fixed -- see no good reason to make configurable */
 	unsigned offsSndBuf;	/* next free spot in send buffer */
+	int errsToReport;	/* (remaining) number of errors to report */
 } instanceData;
 
 /* config data */
@@ -144,6 +145,7 @@ static struct cnfparamdescr actpdescr[] = {
 	{ "ziplevel", eCmdHdlrInt, 0 },
 	{ "compression.mode", eCmdHdlrGetWord, 0 },
 	{ "compression.stream.flushontxend", eCmdHdlrBinary, 0 },
+	{ "maxerrormessages", eCmdHdlrInt, 0 },
 	{ "rebindinterval", eCmdHdlrInt, 0 },
 	{ "streamdriver", eCmdHdlrGetWord, 0 },
 	{ "streamdrivermode", eCmdHdlrInt, 0 },
@@ -329,6 +331,7 @@ ENDfreeCnf
 BEGINcreateInstance
 CODESTARTcreateInstance
 	pData->offsSndBuf = 0;
+	pData->errsToReport = 5;
 ENDcreateInstance
 
 
@@ -372,7 +375,9 @@ static rsRetVal UDPSend(instanceData *pData, char *msg, size_t len)
 	struct addrinfo *r;
 	int i;
 	unsigned lsent = 0;
-	int bSendSuccess;
+	sbool bSendSuccess;
+	int lasterrno;
+	char errStr[1024];
 
 	if(pData->iRebindInterval && (pData->nXmit++ % pData->iRebindInterval == 0)) {
 		dbgprintf("omfwd dropping UDP 'connection' (as configured)\n");
@@ -400,18 +405,30 @@ static rsRetVal UDPSend(instanceData *pData, char *msg, size_t len)
 					bSendSuccess = RSTRUE;
 					break;
 				} else {
-					int eno = errno;
-					char errStr[1024];
-					dbgprintf("sendto() error: %d = %s.\n",
-						eno, rs_strerror_r(eno, errStr, sizeof(errStr)));
+					lasterrno = errno;
+					DBGPRINTF("sendto() error: %d = %s.\n",
+						lasterrno,
+						rs_strerror_r(lasterrno, errStr, sizeof(errStr)));
 				}
 			}
 			if (lsent == len && !send_to_all)
 			       break;
 		}
 		/* finished looping */
-		if (bSendSuccess == RSFALSE) {
+		if(bSendSuccess == RSFALSE) {
 			dbgprintf("error forwarding via udp, suspending\n");
+			if(pData->errsToReport > 0) {
+				rs_strerror_r(lasterrno, errStr, sizeof(errStr));
+				errmsg.LogError(0, RS_RET_ERR_UDPSEND, "omfwd: error sending "
+						"via udp: %s", errStr);
+				if(pData->errsToReport == 1) {
+					errmsg.LogError(0, RS_RET_LAST_ERRREPORT, "omfwd: "
+							"max number of error message emitted "
+							"- further messages will be "
+							"suppressed");
+				}
+				--pData->errsToReport;
+			}
 			iRet = RS_RET_SUSPENDED;
 		}
 	}
@@ -866,6 +883,7 @@ setInstParamDefaults(instanceData *pData)
 	pData->compressionLevel = 9;
 	pData->strmCompFlushOnTxEnd = 1;
 	pData->compressionMode = COMPRESS_NEVER;
+	pData->errsToReport = 5;
 }
 
 BEGINnewActInst
@@ -984,6 +1002,8 @@ CODESTARTnewActInst
 			errmsg.LogError(0, NO_ERRCODE, "Compression requested, but rsyslogd is not compiled "
 				 "with compression support - request ignored.");
 #			endif /* #ifdef USE_NETZIP */
+		} else if(!strcmp(actpblk.descr[i].name, "maxerrormessages")) {
+			pData->errsToReport = (int) pvals[i].val.d.n;
 		} else if(!strcmp(actpblk.descr[i].name, "resendlastmsgonreconnect")) {
 			pData->bResendLastOnRecon = (int) pvals[i].val.d.n;
 		} else if(!strcmp(actpblk.descr[i].name, "template")) {
-- 
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