omrelp: add TCP keepalive configuration

doc/source/configuration/modules/omrelp.rst

@@ -148,6 +148,66 @@ balancers, which in turn forward messages to another physical target
 system.
 
 
+KeepAlive
+^^^^^^^^^
+
+.. csv-table::
+   :header: "type", "default", "mandatory", "|FmtObsoleteName| directive"
+   :widths: auto
+   :class: parameter-table
+
+   "binary", "off", "no", "none"
+
+Enable or disable keep-alive packets at the TCP socket layer. By
+default keep-alive is disabled.
+
+
+KeepAlive.Probes
+^^^^^^^^^^^^^^^^
+
+.. csv-table::
+   :header: "type", "default", "mandatory", "|FmtObsoleteName| directive"
+   :widths: auto
+   :class: parameter-table
+
+   "integer", "0", "no", "none"
+
+The number of keepalive probes to send before considering the
+connection dead. The default, 0, uses the operating system defaults.
+This only has an effect if keep-alive is enabled and may not be
+available on all platforms.
+
+
+KeepAlive.Interval
+^^^^^^^^^^^^^^^^^^
+
+.. csv-table::
+   :header: "type", "default", "mandatory", "|FmtObsoleteName| directive"
+   :widths: auto
+   :class: parameter-table
+
+   "integer", "0", "no", "none"
+
+The interval between subsequent keepalive probes. The default, 0,
+uses the operating system defaults. This only has an effect if
+keep-alive is enabled and may not be available on all platforms.
+
+
+KeepAlive.Time
+^^^^^^^^^^^^^^
+
+.. csv-table::
+   :header: "type", "default", "mandatory", "|FmtObsoleteName| directive"
+   :widths: auto
+   :class: parameter-table
+
+   "integer", "0", "no", "none"
+
+The idle time before the first keepalive probe is sent. The default, 0,
+uses the operating system defaults. This only has an effect if
+keep-alive is enabled and may not be available on all platforms.
+
+
 WindowSize
 ^^^^^^^^^^
 
@@ -374,7 +434,7 @@ manual <http://gnutls.org/manual/html_node/Priority-Strings.html>`__.
 **Note: this is an expert parameter.** Do not use if you do not
 exactly know what you are doing.
 
-tls.tlscfgcmd 
+tls.tlscfgcmd
 ^^^^^^^^^^^^^
 
 .. csv-table::

plugins/omrelp/omrelp.c

@@ -93,6 +93,10 @@ typedef struct _instanceData {
 #endif
     uchar *tplName;
     uchar *localClientIP;
+    sbool bKeepAlive; /* support keep-alive packets */
+    int iKeepAliveProbes;
+    int iKeepAliveTime;
+    int iKeepAliveIntvl;
     struct {
         int nmemb;
         uchar **name;
@@ -136,7 +140,9 @@ static struct cnfparamdescr actpdescr[] = {
     {"tls.tlscfgcmd", eCmdHdlrString, 0},   {"tls.permittedpeer", eCmdHdlrArray, 0},
     {"port", eCmdHdlrGetWord, 0},           {"rebindinterval", eCmdHdlrInt, 0},
     {"windowsize", eCmdHdlrInt, 0},         {"timeout", eCmdHdlrInt, 0},
-    {"conn.timeout", eCmdHdlrInt, 0},       {"localclientip", eCmdHdlrGetWord, 0},
+    {"conn.timeout", eCmdHdlrInt, 0},       {"keepalive", eCmdHdlrBinary, 0},
+    {"keepalive.probes", eCmdHdlrInt, 0},   {"keepalive.time", eCmdHdlrInt, 0},
+    {"keepalive.interval", eCmdHdlrInt, 0}, {"localclientip", eCmdHdlrGetWord, 0},
     {"template", eCmdHdlrGetWord, 0}};
 static struct cnfparamblk actpblk = {CNFPARAMBLK_VERSION, sizeof(actpdescr) / sizeof(struct cnfparamdescr), actpdescr};
 
@@ -210,6 +216,11 @@ static rsRetVal doCreateRelpClient(instanceData *pData, relpClt_t **pRelpClt) {
         ABORT_FINALIZE(RS_RET_RELP_ERR);
     }
     if (relpCltSetWindowSize(*pRelpClt, pData->sizeWindow) != RELP_RET_OK) ABORT_FINALIZE(RS_RET_RELP_ERR);
+#if defined(HAVE_RELPCLTSETKEEPALIVE)
+    if (relpCltSetKeepAlive(*pRelpClt, pData->bKeepAlive, pData->iKeepAliveIntvl, pData->iKeepAliveProbes,
+                            pData->iKeepAliveTime) != RELP_RET_OK)
+        ABORT_FINALIZE(RS_RET_RELP_ERR);
+#endif
     if (pData->bEnableTLS) {
         if (relpCltEnableTLS(*pRelpClt) != RELP_RET_OK) ABORT_FINALIZE(RS_RET_RELP_ERR);
         if (pData->bEnableTLSZip) {
@@ -282,6 +293,10 @@ BEGINcreateInstance
 #if defined(HAVE_RELPENGINESETTLSCFGCMD)
     pData->tlscfgcmd = NULL;
 #endif
+    pData->bKeepAlive = 0;
+    pData->iKeepAliveProbes = 0;
+    pData->iKeepAliveTime = 0;
+    pData->iKeepAliveIntvl = 0;
     pData->permittedPeers.nmemb = 0;
 ENDcreateInstance
 
@@ -344,6 +359,10 @@ static void setInstParamDefaults(instanceData *pData) {
 #if defined(HAVE_RELPENGINESETTLSCFGCMD)
     pData->tlscfgcmd = NULL;
 #endif
+    pData->bKeepAlive = 0;
+    pData->iKeepAliveProbes = 0;
+    pData->iKeepAliveTime = 0;
+    pData->iKeepAliveIntvl = 0;
     pData->permittedPeers.name = NULL;
     pData->permittedPeers.nmemb = 0;
 }
@@ -432,6 +451,14 @@ BEGINnewActInst
             pData->timeout = (unsigned)pvals[i].val.d.n;
         } else if (!strcmp(actpblk.descr[i].name, "conn.timeout")) {
             pData->connTimeout = (int)pvals[i].val.d.n;
+        } else if (!strcmp(actpblk.descr[i].name, "keepalive")) {
+            pData->bKeepAlive = (sbool)pvals[i].val.d.n;
+        } else if (!strcmp(actpblk.descr[i].name, "keepalive.probes")) {
+            pData->iKeepAliveProbes = (int)pvals[i].val.d.n;
+        } else if (!strcmp(actpblk.descr[i].name, "keepalive.time")) {
+            pData->iKeepAliveTime = (int)pvals[i].val.d.n;
+        } else if (!strcmp(actpblk.descr[i].name, "keepalive.interval")) {
+            pData->iKeepAliveIntvl = (int)pvals[i].val.d.n;
         } else if (!strcmp(actpblk.descr[i].name, "rebindinterval")) {
             pData->rebindInterval = (unsigned)pvals[i].val.d.n;
         } else if (!strcmp(actpblk.descr[i].name, "windowsize")) {

tests/Makefile.am

@@ -2252,6 +2252,7 @@ EXTRA_DIST= \
         omfwd-subtree-tpl.sh \
         omfwd_fast_imuxsock.sh \
         omfile_hup-vg.sh \
+	omrelp-keepalive.sh \
         omsendertrack-basic.sh \
 	omsendertrack-basic-vg.sh \
 	omsendertrack-statefile.sh \

tests/omrelp-keepalive.sh

@@ -0,0 +1,53 @@
+#!/bin/bash
+# added 2024-08-07 by ChatGPT, released under ASL 2.0
+. ${srcdir:=.}/diag.sh init
+
+# ensure recent librelp with client keepalive support
+if ! pkg-config --atleast-version=1.12.0 relp 2>/dev/null ; then
+    echo "SKIP: librelp without client keepalive support"
+    exit 77
+fi
+
+export PORT_RCVR="$(get_free_port)"
+
+generate_conf
+add_conf '
+module(load="../plugins/imrelp/.libs/imrelp")
+input(type="imrelp" port="'$PORT_RCVR'")
+
+template(name="outfmt" type="list") {
+        property(name="msg")
+        constant(value="\n")
+}
+:msg, contains, "msgnum:" action(type="omfile" template="outfmt" file="'$RSYSLOG_OUT_LOG'")
+'
+startup
+
+generate_conf 2
+add_conf '
+module(load="../plugins/omrelp/.libs/omrelp")
+module(load="../plugins/imtcp/.libs/imtcp")
+input(type="imtcp" port="0" listenPortFileName="'$RSYSLOG_DYNNAME'.tcpflood_port")
+if $msg contains "msgnum:" then action(type="omrelp" target="127.0.0.1" port="'$PORT_RCVR'" keepalive="on" keepalive.probes="5" keepalive.time="60" keepalive.interval="15")
+' 2
+startup 2
+
+tcpflood -m1 -Ptcpflood_port
+sleep 1
+
+CLIENT_PID=$(cat $RSYSLOG_DYNNAME.2.pid)
+if ss -tnpo | grep -E "pid=$CLIENT_PID" | grep -q keepalive; then
+    :
+else
+    echo "keepalive not set"
+    error_exit 1
+fi
+
+shutdown_when_empty 2
+wait_shutdown 2
+shutdown_when_empty
+wait_shutdown
+
+echo " msgnum:00000000:" | cmp - $RSYSLOG_OUT_LOG || error_exit 1
+
+exit_test