I have a seemingly easy but quite specific question. I have three different node types in my network: a client, an aggregator and the border router (rpl-border-router). There should be a unicast connection between one (or multiple) clients and an aggregator. When the aggregator gets messages of some specific type or when some threshold is reached the aggregator forwards some other message to the border router. The example code of unicast-recevier (aggregator) in the simple-udp-rpl folder creates a RPL DAG the following way:
static void create_rpl_dag(uip_ipaddr_t *ipaddr) {
struct uip_ds6_addr *root_if;
root_if = uip_ds6_addr_lookup(ipaddr);
if(root_if != NULL) {
rpl_dag_t *dag;
uip_ipaddr_t prefix;
rpl_set_root(RPL_DEFAULT_INSTANCE, ipaddr);
dag = rpl_get_any_dag();
uip_ip6addr(&prefix, UIP_DS6_DEFAULT_PREFIX, 0, 0, 0, 0, 0, 0, 0);
rpl_set_prefix(dag, &prefix, 64);
PRINTF("created a new RPL dag\n");
} else {
PRINTF("failed to create a new RPL DAG\n");
}
}
However, since the border router creates a RPL DAG on its own, the receiver (aggregator) cannot send messages to the border router. But removing this RPL code from the receiver results in the inability to receive messages from the sender (client). So the problem is probably somehow connected to RPL. The ContikiRPL code is not really well documented and I am struggling to make progress. Any help is greatly appreciated.
Related
I have a local (household 192.168.0.X) network provided by my router/modem which assigns local IP addresses by the usual Dynamic DNS. I have added an ESP8266 runnning in the WiFi Nat (natp) mode to act as an extender. So it connected to the router as a station and then provides an access point that other devices can connect to. Currently, its subnet is 172...X).
This works in the sense that devices on the extended subnet can see the "world" like google.com etc...
The problem is devices on the 192. network can't see any devices on the extended network.
The source of the problem is pretty obvious: the 192 network devices are all connected by the router which has no clue about any devices connnected to the extender access point.
Is this possible and is there a good ESP 82666 example for this?
If not example, I'm unsure what I'm not understanding-- I'm unsure of what to call this configuration so googling it isn't working.
I feel like there ought to be a way to make the extender just a transparent replicator/relay so the Router is seeing every device and is doing the DHCPS job itself rather than the ESP8266 access point. But I'm stuck.
What sort of configuration approach I can use to expose the devices on the extended network to the computers on the 192 network?
There's a myriad of possible settings but I can't seem to find a permutation that works. (e.g. the Gateway setting or turning off DHCP on the extender access point.) I've tried making the extender network be the same 192.168.0.X rather than 172. But that didn't help.
Detail:
What I have here is a sensor network out in my barn that lives on the access point. I want to be able to access the sensors from inside the house. I've goofed around with workarounds of having the barn devices send their data to a server out in the world. But I want direct access so I can query the devices or do over the air programming directly to the devices from my home computer. I can only do this right now by connecting the home computer to the (slower) extended network access point rather than the high speed home router.
Here's an example of the code I'm modifying (basically one of the ESPWIFI example sketches.)
// NAPT example released to public domain
#if LWIP_FEATURES && !LWIP_IPV6
#define HAVE_NETDUMP 0
#ifndef STASSID
#define STASSID "HouseModem"
#define STAPSK "HouseModemPassword"
#endif
#include <ESP8266WiFi.h>
#include <lwip/napt.h>
#include <lwip/dns.h>
#include <dhcpserver.h>
#define NAPT 1000
#define NAPT_PORT 10
#if HAVE_NETDUMP
#include <NetDump.h>
void dump(int netif_idx, const char* data, size_t len, int out, int success) {
(void)success; // What does this do?
Serial.print(out ? F("out ") : F(" in "));
Serial.printf("%d ", netif_idx);
// optional filter example: if (netDump_is_ARP(data))
{
netDump(Serial, data, len);
//netDumpHex(Serial, data, len);
}
}
#endif
void setup() {
Serial.begin(115200);
Serial.printf("\n\nNAPT Range extender\n");
Serial.printf("Heap on start: %d\n", ESP.getFreeHeap());
#if HAVE_NETDUMP
phy_capture = dump;
#endif
// first, connect to STA so we can get a proper local DNS server
WiFi.mode(WIFI_STA);
WiFi.begin(STASSID, STAPSK);
while (WiFi.status() != WL_CONNECTED) {
Serial.print('.');
delay(500);
}
Serial.printf("\nSTA: %s (dns: %s / %s)\n",
WiFi.localIP().toString().c_str(),
WiFi.dnsIP(0).toString().c_str(),
WiFi.dnsIP(1).toString().c_str());
// give DNS servers to AP side
dhcps_set_dns(0, WiFi.dnsIP(0));
dhcps_set_dns(1, WiFi.dnsIP(1));
WiFi.softAPConfig( // enable AP, with android-compatible google domain
// IPAddress(172, 217, 28, 254),
// IPAddress(172, 217, 28, 254),
// IPAddress(255, 255, 255, 0));
WiFi.localIP(),IPAddress(192,168,0,1),IPAddress(255, 255, 255, 0));
WiFi.softAP(STASSID "extender", STAPSK); // odd way to concat strings
Serial.printf("AP: %s\n", WiFi.softAPIP().toString().c_str());
Serial.printf("Heap before: %d\n", ESP.getFreeHeap());
err_t ret = ip_napt_init(NAPT, NAPT_PORT);
Serial.printf("ip_napt_init(%d,%d): ret=%d (OK=%d)\n", NAPT, NAPT_PORT, (int)ret, (int)ERR_OK);
if (ret == ERR_OK) {
ret = ip_napt_enable_no(SOFTAP_IF, 1);
Serial.printf("ip_napt_enable_no(SOFTAP_IF): ret=%d (OK=%d)\n", (int)ret, (int)ERR_OK);
if (ret == ERR_OK) {
Serial.printf("WiFi Network '%s' with same password is now NATed behind '%s'\n", STASSID "extender", STASSID);
}
}
Serial.printf("Heap after napt init: %d\n", ESP.getFreeHeap());
if (ret != ERR_OK) {
Serial.printf("NAPT initialization failed\n");
}
}
#else
void setup() {
Serial.begin(115200);
Serial.printf("\n\nNAPT not supported in this configuration\n");
}
#endif
void loop() {
}
You can subnetting the routers network from nat devices onwords. So tree like network structure may form.
Let say your router is assigning 192.168.0.x/24 ip to your first hop devices then those devices could modify their access points network with 192.168.1.x/24 and so on upto the possible last hop.
To make it form dynamically on their own you may need to assign common ssid and password to all devices in that structure.
If you could able to achieve this then their may be chances of accessing individual devices from router.
Also you may get the idea of to what hop level individual device seats in network tree by their subnet ip.
I'm using OpenDDS v3.6, and trying to send a message to a specific DDS peer, one of many. In the IDL, the message structure looks like the following:
module Test
{
#pragma DCPS_DATA_TYPE "Test::MyMessage"
#pragma DCPS_DATA_KEY "Test::MyMessage dest_id"
struct MyMessage {
short dest_id;
string txt;
};
};
My understanding is that because the data key is unique, this is a new instance of the topic being written to, and any further msgs written w/ the same data key send to this specific instance of the topic. My send code is as follows:
DDS::ReturnCode_t ret;
Test::MyMessage msg;
// populate msg
msg.dest_id = n;
DDS::InstanceHandle_t handle;
handle = msg_writer->register_instance(msg);
ret = msg_writer->write(msg, handle);
So now I need to figure out how to get the receiving peer to read only from this topic instance and not receive all the other messages being sent to other peers. I started with the following, but not sure how to properly select a specific topic instance.
DDS::InstanceHandle_t instance;
status = msg_dr->take_next_instance(spec, si, 1, DDS::ANY_SAMPLE_STATE,
DDS::ANY_VIEW_STATE, DDS::ANY_INSTANCE_STATE);
Any help much appreciated.
The easiest way to achieve what you are looking for is by using a ContentFilteredTopic. This class is a specialization of the TopicDescription class and allows you to specify an expression (like a SQL WHERE-clause) of the samples that you are interested in.
Suppose you want your DataReader to only receive samples with dest_id equal to 42, then the corresponding code for creating the ContentFilteredTopic would look something like
DDS::ContentFilteredTopic_var cft =
participant->create_contentfilteredtopic("MyTopic-Filtered",
topic,
"dest_id = 42",
StringSeq());
From there on, you create your DataReader using cft as the parameter for the TopicDescription. The resulting reader will look like a regular DataReader, except that it only receives the desired samples and nothing else. Since the field dest_id happens to be the field that identifies the instance, the end result is that you will only have one instance in your DataReader.
You can check out the DDS specification (section 7.1.2.3.3) or OpenDDS Developer's Guide (section 5.2) for more details.
I have an urgent need to send a canonical message (M1) out of an orchestration and need to map the canonical message to another message (M2). The resulting message (M2) has to be Wrapped in another request message (M3) before sending it to a web service.
I can't perform the initial transform in the orchestration as I can only deal with the canonical schema internally.
Whats the best way to achieve this 2 stage transform outside of the orchestration?
Thanks in advance!
You could make a pipeline component that applies each map sequentially. Then configure the port to use a pipeline with this component.
private Stream ApplyMap(Stream originalStream, Type mapType)
{
var transform = TransformMetaData.For(mapType).Transform;
var argList = TransformMetaData.For(mapType).ArgumentList;
XmlReader input = XmlReader.Create(originalStream);
Stream outputStream = new VirtualStream();
using (var outputWriter = XmlWriter.Create(outputStream))
{
transform.Transform(new XPathDocument(input), argList, outputWriter, null);
}
outputStream.Flush();
outputStream.Position = 0;
XmlReader outputReader = XmlReader.Create(outputStream);
return outputReader;
}
Then in the pipeline component's Execute method:
Type mapType1 = Type.GetType("YourMapNamespace.Map1, YourAssemblyName,...");
Type mapType2 = Type.GetType("YourMapNamespace.Map2, YourAssemblyName,...");
Stream originalStream = inmsg.BodyPart.GetOriginalDataStream();
Stream mappedStream =
ApplyMap(
ApplyMap(originalStream, mapType1),
mapType2
);
inmsg.BodyPart.Data = mappedStream;
context.ResourceTracker.AddResource(mappedStream);
Note that this example does everything in memory so it could be a problem for large messages. I'll try to find a better example that uses streaming (or worse case, you can use VirtualStream to avoid keeping everything in memory)
If you can use the ESB Toolkit, the ideal approach would be to use an itinerary (Richard Seroter has a good article on that approach here). If that's not an option, here's an approach I've used in the past:
http://blogs.msdn.com/b/chrisromp/archive/2008/08/06/stacking-maps-in-biztalk-server.aspx
I want to prepend IP header on an existing IP packet while inside NF_HOOK_LOCAL_OUT. The issue I face is that the skb expansion functions (such as copy/clone/expand/reallocate header) allocate a new sk_buff. We can not return this newly allocated pointer since netfilter hook function no longer (kernel version 2.6.31) passes the skb pointer's address (passes by value). How I solved the issue is as follows:
1. I got a new skb using skb_header_realloc(). This copies all the data from skb.
2. I modified the new skb (call it skb2) to prepend the new IP header, set appropriate values in the new IP header.
3. Replace the contents of the original skb (passed in the Netfilter hook function) with the contents of the skb2 using skb_morph(). Returned NF_ACCEPT.
Is this the only way of achieving what I intended to? Is there a more efficient solution? Are there other use cases of skb_morph (besides the IP reassembly code)?
This works for me, in 2.6 kernels:
...
struct iphdr* iph;
if (skb_headroom(skb) < sizeof(struct iphdr))
if (0 != pskb_expand_head(skb, sizeof(struct iphdr) - skb_headroom(skb), 0, GFP_ATOMIC)) {
printk("YOUR FAVOURITE ERROR MESSAGE");
kfree_skb(skb);
return NF_STOLEN;
}
iph = (struct iphdr*) skb_push(skb, sizeof(struct iphdr));
//Fill ip packet
return NF_ACCEPT;
Hope it helps.
In the tutorial provided at:
http://www.erlang.org/doc/tutorial/cnode.html
There is the following example:
/* cnode_s.c */
#include
#include
#include
#include
#include "erl_interface.h"
#include "ei.h"
#define BUFSIZE 1000
int main(int argc, char **argv) {
int port; /* Listen port number */
int listen; /* Listen socket */
int fd; /* fd to Erlang node */
ErlConnect conn; /* Connection data */
int loop = 1; /* Loop flag */
int got; /* Result of receive */
unsigned char buf[BUFSIZE]; /* Buffer for incoming message */
ErlMessage emsg; /* Incoming message */
ETERM *fromp, *tuplep, *fnp, *argp, *resp;
int res;
port = atoi(argv[1]);
erl_init(NULL, 0);
if (erl_connect_init(1, "secretcookie", 0) == -1)
erl_err_quit("erl_connect_init");
/* Make a listen socket */
if ((listen = my_listen(port))
I suspect that erl_receive_msg is a blocking call, and I don't know how to overcome this. In C network programming there is the "select" statement but in the Erlang EI API I don't know whether there is such a statement.
Basically I want to build a C node, that continuously sends messages to Erlang nodes. For simplicity suppose there is only one Erlang node.
The Erlang node has to process the messages it receives from the C node. The Erlang node is not supposed to ensure that it has received the message, not does it have to reply with the result of processing. Therefore once the message is sent I don't care about it faith.
One might think that one could modify the code as:
...
if (emsg.type == ERL_REG_SEND) {
...
while(1) {
//generate tuple
erl_send(fd, fromp, tuple);
//free alloc resources
}
...
}
This will produce an infinite loop in which we produce and consume (send) messages.
But there is an important problem: if I do this, then the C node might send too many messages to the Erlang node (so there should be a way to send a message from the Erlang node to the C node to slow down), or the Erlang node might think that the C node is down.
I know that the questions must be short an suite (this is long and ugly), but summing up:
What mechanism (procedure call, algorithm) one might use to develop an eager producer in C for a lazy consumer in Erlang, such that both parties are aware of the underlying context ?
I use Port Drivers myself for the case you are describing (haven't touched the C nodes because I'd rather have more decoupling).
Have a look at the Port Driver library for Erlang: EPAPI. There is a project that leverages this library: Erland DBus.
Did you check the ei_receive_msg_tmo function? I suppose it works similar to the receive after construct of Erlang, so if you set timeout to 0, it will be non-blocking.
I believe erl_interface is deprecated, and ei should be used instead. This might be a complete misinformation though...
you need to take a closer look at the tutorial link that you posted. (search for "And finally we have the code for the C node client.") You will see that the author provided a client cnode implementation. It looks rational.