I am using RTI DDS 5.2.3.17 and would like to get the IP address of the remote DataReader/Subscriber that I am sending messages to, to add to some log messages.
How would I go about doing this I am having some trouble in just forming the logic of what to do?
The mechanism described for your question here, using the SampleInfo, will not work for obtaining the IP address of DataReaders
Depending on the situation, the easiest approach would probably be to install a listener on your DataWriter and inspect the last_subscription_handle parameter when the DataWriterListener’s on_publication_matched() callback is invoked. As explained in the RTI Knowledge Base article Accessing the GUID of Connext DDS Entities, the instance handle is essentially another GUID for you to inspect.
If you have many readers that you need to keep track of, it might be easier to subscribe to the BuiltinTopics used for discovery, as explained in that same KB article. That is more work though.
Again, all of this is assuming you are looking for the IPv4 address. Also note that this is not a publicly exposed mechanism, so things might change in the future. And all of this breaks at the moment that your application explicitly sets its GUID.
Related
I use the Ble library, but I want to connect/pair only the first device/phone. After this only the first device is allowed to reconnect. How do I implement this? Is there a best practice? Do I need to filter the deviceid? Or are there better ways to acchieve this?
That can be achieved using the Filter Accept List (previously known as White List), which is standard in the BLE spec. How to use it depends on the Bluetooth stack you are using, so you should check the manual for the Bluetooth stack you are using (you didn't mention).
If you want to support Random Resolvable addresses, you can use the Resolving List where you put the corresponding IRKs.
But a personal opinion is to instead always let any device connect to your device, and then secure sensitive services using MITM-secure authentication instead (pairing). That could potentially lead to a better experience for the user, because otherwise any connection attempt from "wrong" device will just lead to a unknown connection error from the user which might be hard to understand.
I'm working on a project that has server and client roles. I would like to have servers and clients automatically detecting each other. At a first glance, zeroconf seems to be the best solution. But it would add a dependency, Bonjour, to the project. I use Qt for the GUI and Qt has native support of broadcast and multicast. So I'm wondering if it's feasible to just use those features to replace zeroconf?
Here is a decent post about how zeroconf works.
I don't think I need the features of obtaining an IP Address and obtaining a Hostname from zeroconf. All I want is let one instance be aware of other instance's existence.
My current plan is combining broadcast and multicast. Each server chooses a unique multicast group and broadcast this group to the others. When a client wants to connect a to specific server, it joins the corresponding group.
Some people mention that it's normal that routers blocking local broadcast. If this is true, my plan would not be feasible.
Is there any standard way to implement this rather than using zeroconf?
Supposed I have two services that need to share and / or exchange data. Both instances are separate from each other, and they shall not know anything about where the other part is located.
Now in order for them to be able to share and / or exchange data, they need to connect to each other.
How do they find each other without the need to configure the IP addresses explicitly? In other words: How could they detect each other automatically?
Basically, I have two ideas:
Pull: You need to have a central service where they register. Then you can ask that service for the address of a service, and that service then returns those data. While this works, it has the drawback that it only shifts the problem to the next level: What if I have multiple instances of that service, and I don't want them to know each other in advance?
Push: Each service broadcasts its own address, so that other services get it to know. Each service repeats this from time to time. Drawback: This does hardly work in the internet.
Any idea of how I could solve this in an intelligent way?
PS: If you want to say so, I'm looking for a way to handle dynamic IPs without the need for a central DNS server.
The usual way is to have some fault-tolerant server where services register and can then look for other services - Curator framework implements that over zookeeper.
If you want autodiscovery then you should probably implement some sort of gossip protocol so that the servers would know which other servers are out there in a reliable way. You should keep in mind that getting gossip protocols right is tricky (e.g. some of past Amazon cloud failures where due to problems in their implementation)
"broadcast packets are not forwarded everywhere on a network, but only to devices within a broadcast domain."
If your devices are on different broadcast domains then broadcasting is not going to work.
You are probably going to have to implement your own central service, unless you can use one of the free dynamic dns servers, for example: Free
Currently, I am running asp.net on a 4.0 Framework. I found one section of my code that is truly expensive for me to use. I currently get the IP Address and the reverse dns for users accessing my site, however, I am trying to keep performance in mind.
Is there a cheaper alternative to this?
return System.Net.Dns.GetHostEntry(HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"]).HostName;
Since the ServerVariables indexer returns a string, your code snippet calls the GetHostEntry string overload. Its documentation describes a three-step lookup algorithm, with two separate queries. The GetHostEntry IPAddress overload documentation doesn't describe any similar process, so perhaps it saves a query. Then again, it seems to provide the same info (all IP address and host names), so maybe it's the same, but just documented differently.
Is it possible to know network card id of the user host computer from where the request is coming like IP address. I am interesting to know if it is possible at IIS or asp.net level or any other possible way of knowing it?
As far as getting network card information is concerned, I see little hope for you here seeing as a client's hardware profile is not something naturally pushed down the wire as a matter of course, however see:
HttpContext.Current.Request.UserHostAddress
Or
HttpContext.Current.Request.ServerVariables("remote_addr")
This value will give you the IP address of the calling client, although they may be hitting you through a proxy and therefore can't be guaranteed to be a machine specific address.
If by "network card ID" you mean the Ethernet MAC address, that's assuming a particular technology on the remote side that you have no way of knowing whether or not it is used. Sure, Ethernet is used pretty much everywhere these days, but are you willing to limit yourself to clients that use that particular hardware architecture? So even if it were possible, I doubt you'd want to go down that route.
If what you want is a unique identifier per client computer, you are probably better off issuing some sort of token yourself. A cookie with a randomly generated session ID should work fairly well.