alex/esp-idf
alex/esp-idf
1
0
Fork 0
mirror of https://github.com/espressif/esp-idf.git synced 2024-10-05 20:47:46 -04:00
Code Issues Actions 2 Packages Projects Releases Wiki Activity
a60b1428d5
esp-idf/examples/protocols/sockets/udp_multicast
History
gfrodo 269c4c74d2 udp_multicast_example: better handling wrong addresses 
inet_aton returns 0 on failure, but socket_add_ipv4_multicast_group has to return negative values for failures
getaddrinfo sets res to zero of address could not resolved, but doesn't necessarily return an
error. res is now checked for zero before dereferencing

Merges https://github.com/espressif/esp-idf/pull/2814
2019-04-17 06:52:23 +00:00
..
main udp_multicast_example: better handling wrong addresses 2019-04-17 06:52:23 +00:00
CMakeLists.txt examples/protocols/sockets: use common network component 2019-04-15 03:32:05 +00:00
Makefile examples/protocols/sockets: use common network component 2019-04-15 03:32:05 +00:00
README.md examples/protocols/sockets: use common network component 2019-04-15 03:32:05 +00:00

README.md

UDP Multicast Example

This example shows how to use the IPV4 & IPV6 UDP multicast features via the BSD-style sockets interface.

Behaviour

The behaviour of the example is:

  • Listens to specified multicast addresses (one IPV4 and/or one IPV6).
  • Print any UDP packets received as ASCII text.
  • If no packets are received it will periodicially (after 2.5 seconds) send its own plaintext packet(s) to the multicast address(es).

Configuration

Run make menuconfig (or idf.py menuconfig if using CMake build system).

Configure Wi-Fi or Ethernet under "Example Connection Configuration" menu. See "Establishing Wi-Fi or Ethernet Connection" section in examples/protocols/README.md for more details.

The "Example Configuration" menu allows you to configure the details of the example:

  • IP Mode: IPV4 & IPV6 dual, IPV4 only, or IPv6 only.
  • Multicast addresses for IPV4 and/or IPV6.
  • Enable multicast socket loopback (ie should the socket receive its own multicast transmissions.)
  • Change the interface to add the multicast group on (default interface, or WiFi STA interface.) Both methods are valid.

Implementation Details

In IPV4 & IPV6 dual mode, an IPV6 socket is created and the "dual mode" options described in RFC4038 are used to bind it to the default address for both IPV4 & IPV6 and join both the configured IPV4 & IPV6 multicast groups. Otherwise, a single socket of the appropriate type is created.

The socket is always bound to the default address, so it will also receive unicast packets. If you only want to receive multicast packets for a particular address, bind() to that multicast address instead.

Host Tools

There are many host-side tools which can be used to interact with the UDP multicast example. One command line tool is socat which can send and receive many kinds of packets.

Send IPV4 multicast via socat

echo "Hi there, IPv4!" | socat STDIO UDP4-DATAGRAM:232.10.11.12:3333,ip-multicast-if=(host_ip_addr)

Replace 232.10.11.12:3333 with the IPV4 multicast address and port, and (host_ip_addr) with the host's IP address (used to find the interface to send the multicast packet on.)

Receive IPV4 multicast via socat

socat STDIO UDP4-RECVFROM:3333,ip-add-membership=232.10.11.12:(host_ip_addr)

Replace :3333 and 232.10.11.12 with the port and IPV4 multicast address, respectively. Replace (host_ip_addr) with the host IP address, used to find the interface to listen on.

(The ,ip-add-membership=... clause may not be necessary, depending on your network configuration.)

Send IPV6 multicast via socat

echo "Hi there, IPV6!" | socat STDIO UDP6-DATAGRAM:[ff02::fc]:3333

Replace [ff02::fc]:3333 with the IPV6 multicast address and port, respectively.

Receive IPV6 multicast via socat

At time of writing this is not possible without patching socat. Use a different tool or programming language to receive IPV6 multicast packets.

About Examples

See the README.md file in the upper level 'examples' directory for general information about examples.