From: Ferry Huberts <ferry.huberts@pelagic.nl>
Date: Wed, 29 Jan 2014 09:39:49 +0000 (+0100)
Subject: p2pd: add UseTTLDecrement configuration setting
X-Git-Tag: v0.6.7~41^2~41
X-Git-Url: http://olsr.org/git/?p=olsrd.git;a=commitdiff_plain;h=7996735cec7058153aa675bc402c08e058862079

p2pd: add UseTTLDecrement configuration setting

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
---

diff --git a/lib/p2pd/README b/lib/p2pd/README
index c89f2922..b5c44a50 100644
--- a/lib/p2pd/README
+++ b/lib/p2pd/README
@@ -67,6 +67,8 @@ PlParam     "P2pdTtl"     "5"
 PlParam     "UdpDestPort" "255.255.255.255 1211"
 #   MDNS multicast (draft-cheshire-dnsext-multicastdns)
 PlParam     "UdpDestPort" "224.0.0.251 5353"
+# Set to 1 to decrement the TTL on the packet going into the OLSR network (default 0)
+#PlParam     "UseTTLDecrement" "0"
 }
 
 Where eth0 and eth1 are the names of the interfaces where you want to capture
diff --git a/lib/p2pd/src/olsrd_plugin.c b/lib/p2pd/src/olsrd_plugin.c
index 737cef87..da2d9c0c 100644
--- a/lib/p2pd/src/olsrd_plugin.c
+++ b/lib/p2pd/src/olsrd_plugin.c
@@ -112,6 +112,7 @@ static const struct olsrd_plugin_parameters plugin_parameters[] = {
   {.name = "P2pdTtl", .set_plugin_parameter = &SetP2pdTtl, .data = NULL },
   {.name = "UdpDestPort",.set_plugin_parameter = &AddUdpDestPort,.data = NULL},
   {.name = "UseHashFilter",.set_plugin_parameter = &SetP2pdUseHashFilter,.data = NULL},
+  {.name = "UseTTLDecrement",.set_plugin_parameter = &SetP2pdUseTtlDecrement,.data = NULL},
 };
 
 /* -------------------------------------------------------------------------
diff --git a/lib/p2pd/src/p2pd.c b/lib/p2pd/src/p2pd.c
index b696c4fc..f9db2a7e 100644
--- a/lib/p2pd/src/p2pd.c
+++ b/lib/p2pd/src/p2pd.c
@@ -85,6 +85,7 @@
 
 int P2pdTtl                        = 0;
 int P2pdUseHash                    = 0;  /* Switch off hash filter by default */
+int P2pdUseTtlDecrement            = 0;  /* No TTL decrement by default */
 int P2pdDuplicateTimeout           = P2PD_VALID_TIME;
 
 /* List of UDP destination address and port information */
@@ -622,6 +623,7 @@ P2pdPacketCaptured(unsigned char *encapsulationUdpData, int nBytes)
   struct ip *ipHeader;         /* The IP header inside the captured IP packet */
   struct ip6_hdr *ipHeader6;   /* The IP header inside the captured IP packet */
   struct udphdr *udpHeader;
+  uint8_t * ttl = NULL;
   u_int16_t destPort;
 
   if ((encapsulationUdpData[0] & 0xf0) == 0x40) {       //IPV4
@@ -662,6 +664,8 @@ P2pdPacketCaptured(unsigned char *encapsulationUdpData, int nBytes)
 #endif /* INCLUDE_DEBUG_OUTPUT */
        return;
     }
+
+    ttl = &ipHeader->ip_ttl;
   }                            //END IPV4
   else if ((encapsulationUdpData[0] & 0xf0) == 0x60) {  //IPv6
 
@@ -703,11 +707,24 @@ P2pdPacketCaptured(unsigned char *encapsulationUdpData, int nBytes)
 #endif /* INCLUDE_DEBUG_OUTPUT */
       return;
     }
+
+    ttl = &ipHeader6->ip6_ctlun.ip6_un1.ip6_un1_hlim;
   }                             //END IPV6
   else {
     return;                     //Is not IP packet
   }
 
+  if (P2pdUseTtlDecrement) {
+    assert(ttl);
+    if (!*ttl) {
+      return;
+    }
+    *ttl -= 1;
+    if (!*ttl) {
+      return;
+    }
+  }
+
   // send the packet to OLSR forward mechanism
   olsr_p2pd_gen(encapsulationUdpData, nBytes);
 }                               /* P2pdPacketCaptured */
@@ -861,6 +878,27 @@ SetP2pdUseHashFilter(const char *value,
   return 0;
 }
 
+/* -------------------------------------------------------------------------
+ * Function   : SetP2pdUseTtlDecrement
+ * Description: Set the TTL decrement lag for this plug-in
+ * Input      : value - parameter value to evaluate
+ *              data  - data associated with this parameter (unused in this app)
+ *              addon - additional parameter data
+ * Output     : none
+ * Return     : Always 0
+ * Data Used  : P2pdUseTtlDecrement
+ * ------------------------------------------------------------------------- */
+int
+SetP2pdUseTtlDecrement(const char *value,
+                     void *data __attribute__ ((unused)),
+                     set_plugin_parameter_addon addon __attribute__ ((unused)))
+{
+  assert(value != NULL);
+  P2pdUseTtlDecrement = atoi(value);
+
+  return 0;
+}
+
 /* -------------------------------------------------------------------------
  * Function   : AddUdpDestPort
  * Description: Set the UDP destination/port combination as an entry in the
diff --git a/lib/p2pd/src/p2pd.h b/lib/p2pd/src/p2pd.h
index 4f90bbf9..5d1762f1 100644
--- a/lib/p2pd/src/p2pd.h
+++ b/lib/p2pd/src/p2pd.h
@@ -99,6 +99,7 @@ int AddUdpDestPort(const char *value, void *data __attribute__ ((unused)), set_p
 bool InUdpDestPortList(int ip_version, union olsr_ip_addr *addr, uint16_t port);
 int SetP2pdTtl(const char *value, void *data __attribute__ ((unused)), set_plugin_parameter_addon addon __attribute__ ((unused)));
 int SetP2pdUseHashFilter(const char *value, void *data __attribute__ ((unused)), set_plugin_parameter_addon addon __attribute__ ((unused)));
+int SetP2pdUseTtlDecrement(const char *value, void *data __attribute__ ((unused)), set_plugin_parameter_addon addon __attribute__ ((unused)));
 bool p2pd_message_seen(struct node **head, struct node **tail, union olsr_message *m);
 void p2pd_store_message(struct node **head, struct node **tail, union olsr_message *m);
 bool p2pd_is_duplicate_message(union olsr_message *msg);