From 28149effa71a5df0a40d7f226ced571adc8fdf5c Mon Sep 17 00:00:00 2001
From: Brian Somers <brian@FreeBSD.org>
Date: Thu, 30 Sep 1999 07:23:13 +0000
Subject: [PATCH] Support GRE packets

Submitted by: Harry Starr <starr@gccs.com.au>
---
 usr.sbin/ppp/filter.c | 25 ++++++++++++++++++++++++-
 usr.sbin/ppp/filter.h |  3 +++
 usr.sbin/ppp/ip.c     | 22 ++++++++++++++++++++++
 3 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/usr.sbin/ppp/filter.c b/usr.sbin/ppp/filter.c
index 16694665bcf3..217c177fbf78 100644
--- a/usr.sbin/ppp/filter.c
+++ b/usr.sbin/ppp/filter.c
@@ -277,6 +277,24 @@ ParseIgmp(int argc, char const * const *argv, struct filterent *tgt)
   return 1;
 }
 
+#ifdef P_GRE
+static int
+ParseGRE(int argc, char const * const *argv, struct filterent *tgt)
+{
+  /*
+   * Filter currently is a catch-all. Requests are either permitted or
+   * dropped.
+   */
+  if (argc != 0) {
+    log_Printf(LogWARN, "ParseGRE: Too many parameters\n");
+    return 0;
+  } else
+    tgt->f_srcop = OP_NONE;
+
+  return 1;
+}
+#endif
+
 #ifdef P_OSPF
 static int
 ParseOspf(int argc, char const * const *argv, struct filterent *tgt)
@@ -457,6 +475,11 @@ Parse(struct ipcp *ipcp, int argc, char const *const *argv,
   case P_OSPF:
     val = ParseOspf(argc, argv, &filterdata);
     break;
+#endif
+#ifdef P_GRE
+  case P_GRE:
+    val = ParseGRE(argc, argv, &filterdata);
+    break;
 #endif
   }
 
@@ -596,7 +619,7 @@ filter_Show(struct cmdargs const *arg)
 }
 
 static const char *protoname[] = {
-  "none", "tcp", "udp", "icmp", "ospf", "igmp"
+  "none", "tcp", "udp", "icmp", "ospf", "igmp", "gre"
 };
 
 const char *
diff --git a/usr.sbin/ppp/filter.h b/usr.sbin/ppp/filter.h
index 9eef6960af26..03922cd21d13 100644
--- a/usr.sbin/ppp/filter.h
+++ b/usr.sbin/ppp/filter.h
@@ -29,6 +29,9 @@
 #define	P_OSPF	4
 #endif
 #define	P_IGMP	5
+#ifdef IPPROTO_GRE
+#define P_GRE   6
+#endif
 
 /* Operations - f_srcop, f_dstop */
 #define	OP_NONE	0
diff --git a/usr.sbin/ppp/ip.c b/usr.sbin/ppp/ip.c
index f1219d000d12..2e5f00c21efa 100644
--- a/usr.sbin/ppp/ip.c
+++ b/usr.sbin/ppp/ip.c
@@ -170,6 +170,15 @@ FilterCheck(const struct ip *pip, const struct filter *filter)
 	    estab = syn = finrst = -1;
 	    sport = ntohs(0);
 	    break;
+#ifdef IPPROTO_GRE
+          case IPPROTO_GRE:
+            cproto = P_GRE;
+            if (datalen < 2)    /* GRE uses 2-octet+ messages */
+              return (1);
+            estab = syn = finrst = -1;
+            sport = ntohs(0);
+            break;
+#endif
 #ifdef IPPROTO_OSPFIGP
 	  case IPPROTO_OSPFIGP:
 	    cproto = P_OSPF;
@@ -360,6 +369,19 @@ PacketCheck(struct bundle *bundle, char *cp, int nb, struct filter *filter)
     }
     break;
 
+#ifdef IPPROTO_GRE
+  case IPPROTO_GRE:
+    if (logit && loglen < sizeof logbuf) {
+      snprintf(logbuf + loglen, sizeof logbuf - loglen,
+          "GRE: %s ---> ", inet_ntoa(pip->ip_src));
+      loglen += strlen(logbuf + loglen);
+      snprintf(logbuf + loglen, sizeof logbuf - loglen,
+              "%s", inet_ntoa(pip->ip_dst));
+      loglen += strlen(logbuf + loglen);
+    }
+    break;
+#endif
+
 #ifdef IPPROTO_OSPFIGP
   case IPPROTO_OSPFIGP:
     if (logit && loglen < sizeof logbuf) {