Jami is unable to use the local area network without a network connection

When only the local LAN is connected, devices cannot communicate with each other.

Because Jami seems to have to be connected to the internet to use it. If there is no internet, Jami will prompt 'No network connection'.

This situation should be easily reproducible, but I am still willing to provide relevant records if gentlemen need them.

I think that if it can be compatible with a local area network, not just the internet, it may allow Jami to have similar functions as Briar, and Jami can make voice and video calls, which is a great feature of Jami.

changed title from Local DHT function failure to Jami is unable to use the local area network without a network connection

Maybe this is a similar issue: jami-docs#9 (comment 38594)

I found that Jami's Android client has been updated with a new version. After the update, I will try to see if I can send messages between local devices normally without connecting to the internet. I think it could be the same problem,

I have enabled Local Peer Discovery, but obviously it doesn't seem to work without the internet. Of course, it is also possible that our mobile hotspot does not support local broadcasting?

I don't know if Jami will send messages to devices on the local network through the internet when he has a local network. This is just a novice's doubt,please don't take it to heart. Another issue is that sometimes Jami's video transmission seems to be a bit slow, and I need to wait for a while to see my friend's video footage, but this is not a very important issue.

Another issue is that sometimes Jami's video transmission seems to be a bit slow, and I need to wait for a while to see my friend's video footage, but this is not a very important issue

Probably the same issue: #1212

@El4 It seems that it is, but Hardware acceleration should be enabled by default. I haven't changed this option, but it is enabled when I check the settings

added bug label

If there is no internet, Jami will prompt 'No network connection'.

Actually this should be ok. Because it's from the Android settings, you should got a question mark on your wifi. This means android cannot reach Google DNS (generally it's done like this) but your local wifi can work without any issue.

What is the configuration of your account (proxy/push/etc)? https://docs.jami.net/user/lan-only.html

Of course, it is also possible that our mobile hotspot does not support local broadcasting?

One way to verify in general is to plug a printer on the network as it's the same feature (local broadcast) if possible.

I don't know if Jami will send messages to devices on the local network through the internet when he has a local network

It will use the local network. Details are on docs.jami.net

@sblin My account configurations for several devices are quite similar, they are all Android devices,

The initial server has not been modified,

UPnP is enabled and DHT proxy is used (the result remains unchanged when not in use, DHT proxy is the default setting and I did not modify it)

Enable Local Peer Discovery, disable STUN, and enable default TURN.

The options on the computer are roughly the same, but there is no STUN option.

Yes, all of my devices tried while disconnected from the network, but I failed, but my phone can connect to the printer on the wireless network

When my phone is disconnected from the network, they can transfer files between them, including my computer, but when using Jami, it will prompt 'no network connection' and cannot send messages to each other

DHT proxy is used

It should not, for a LAN as you probably don't have the proxy in your LAN. Moreover push will not work in a LAN

turn may be disabled/ignored as it's the same. Cf the doc I sent

@sblin Following your prompt, I have closed the DHT agent and TURN, STUN.

I did not modify the boot server, only enabled UPnP and Local Peer Discovery.

But I can't send messages between my devices.

I have a record here, I wonder if you need it?

I remember that OpenDHT use multicast for local peer discovery.

@sblin I think this bug is in OpenDHT, hotspot device gets "No such device" error.
https://git.jami.net/savoirfairelinux/opendht/-/blob/5e4bbcdbbe3eb76305aab2129f5017eb0be47a2d/src/peer_discovery.cpp#L90
https://git.jami.net/savoirfairelinux/opendht/-/blob/5e4bbcdbbe3eb76305aab2129f5017eb0be47a2d/src/peer_discovery.cpp#L290
Can we specify an interface then retry?

ip::multicast::join_group
https://github.com/boostorg/asio/blob/2e49b21732e5d1bb3bb98f209164c30816b0bc79/include/boost/asio/ip/detail/socket_option.hpp#L419-L429
https://github.com/boostorg/asio/blob/2e49b21732e5d1bb3bb98f209164c30816b0bc79/include/boost/asio/ip/detail/socket_option.hpp#L432-L444

https://www.boost.org/doc/libs/1_84_0/doc/html/boost_asio/reference/ip__multicast__outbound_interface.html

if(domain.family() == AF_INET) {
  sockFd_.set_option(asio::ip::multicast::outbound_interface(my_interface));
  sockFd_.set_option(asio::ip::multicast::join_group(sockAddrSend_.address().to_v4(), my_interface));
}

@Lanius-collaris maybe related #1360

I tried Jami on a LAN yesterday, but I got weird result.

Environment

OS version of device A: Android 10

OS version of device B: Android 13

Jami version: 20230602-01 f-droid

Settings

Push notifications: disabled

DHT proxy: disabled

Local peer discovery: enabled

Steps

1. Enable the account on device A

2. Enable the account on device B
   The switch of account turned orange.

3. Run a node with "dhtnode" in termux dhtnode -D -p 4222

Immediately dntnode started, Jami went online.

2023-06-16 edited

I captured packets with tcpdump

sudo tcpdump -vv -i enp2s0 -nn 'udp and host 239.192.0.1'

Earlier versions send packets to 239.192.0.1:8888 as soon as I enable the account even if the cable is disconnected. At least 20220615-01 f-droid works.

04:23:02.606975 IP (tos 0x0, ttl 1, id 9082, offset 0, flags [DF], proto UDP (17), length 30)
    192.168.1.72.8888 > 239.192.0.1.8888: [udp sum ok] UDP, length 2
04:23:02.607006 IP (tos 0x0, ttl 1, id 9083, offset 0, flags [DF], proto UDP (17), length 60)
    192.168.1.72.8888 > 239.192.0.1.8888: [bad udp cksum 0xb1eb -> 0xb3ba!] UDP, length 32

But 20230602-01 f-droid behaves differently, it doesn't seem to send multicast packets if it's not able to reach cached nodes or bootstrap in settings. (?)

2023-06-24 edited

20230616-01 f-droid seems OK.

mentioned in issue #1233

added BacklogHigh label

I found that in Briar, local networks are available in environments without the internet.

This is just a suggestion, perhaps Jami can draw inspiration from Briar.

Jami's local network still seems to have some issues, and Briar is functioning normally. I hope to provide some assistance within my capabilities.

Thank you.

A workaround has been added to OpenDHT, I hope it helps.
https://github.com/savoirfairelinux/opendht/blob/9dad7c69fd343f30e44218b5754f1357d110355e/src/peer_discovery.cpp#L93-L117

https://github.com/savoirfairelinux/opendht/blob/master/src/compat/getif_workaround_android.h

In non connected mobile hotspot, the phone that activated the hotspot cannot use Jami, but other phones connected to this hotspot can use Jami normally in LAN mode. This is the result we obtained last time, and we don't know if this is still the case recently.

Is this fixed?

Similar to the original, devices with hotspot enabled cannot connect to other devices.

This problem is even more serious because the local network function is completely disabled when using a mobile hotspot. Previously, at least the hotspot enabled by the phone could be used to build a local area network.

In the latest versions of Android 424 and Windows 202405161705, other devices are no longer able to use the hotspot of their phones to achieve local area network communication, but at least last year this feature was possible.

mentioned in issue jami-daemon#1036