esp-idf/examples/protocols/mdns

mDNS example

Shows how to use mDNS to advertise lookup services and hosts

Example workflow

• mDNS is initialized with host name and instance name defined through make menuconfig and _http._tcp service is added to be advertised
• WiFi STA is started and trying to connect to the access point defined through make menuconfig
• The system event handler is used to pass the network events to mDNS so the service is aware when the interface comes up or down
• GPIO0 (BOOT Button) is initialized as pulled-up input that can be monitored for button press
• Example task is started to check if the button is pressed so it can execute the mDNS queries defined

Configure the project

make menuconfig

• Set Default serial port under Serial flasher config.
• Set WiFi SSID and WiFi Password for the board to connect to AP.
• Set mDNS Hostname as host name prefix for the device and its instance name in mDNS Instance Name
• Disable Resolve test services to prevent the example from querying defined names/services on startup (cause warnings in example logs, as illustrated below)

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

make -j4 flash monitor

• Wait for WiFi to connect to your access point
• You can now ping the device at [board-hostname].local, where [board-hostname] is a string created from preconfigured hostname (esp32-mdns by default) and last 3 bytes from device MAC address. Please check the serial output log for the specific board-hostname (esp32-mdns_80FFFF in the log below)
• You can also browse for _http._tcp on the same network to find the advertised service
• Pressing the BOOT button will start querying the local network for the predefined in check_button hosts and services

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example Output

I (0) cpu_start: Starting scheduler on APP CPU.
I (276) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
I (276) mdns-test: mdns hostname set to: [esp32-mdns_80FFFF]
I (286) wifi: wifi driver task: 3ffc2fa4, prio:23, stack:3584, core=0
I (286) wifi: wifi firmware version: a3be639
I (286) wifi: config NVS flash: enabled
I (296) wifi: config nano formating: disabled
I (296) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
I (306) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
I (336) wifi: Init dynamic tx buffer num: 32
I (336) wifi: Init data frame dynamic rx buffer num: 32
I (336) wifi: Init management frame dynamic rx buffer num: 32
I (346) wifi: Init static rx buffer size: 1600
I (346) wifi: Init static rx buffer num: 10
I (346) wifi: Init dynamic rx buffer num: 32
I (356) mdns-test: Setting WiFi configuration SSID myssid...
I (426) phy: phy_version: 4000, b6198fa, Sep  3 2018, 15:11:06, 0, 0
I (426) wifi: mode : sta (30:ae:a4:80:FF:FF)
I (426) gpio: GPIO[0]| InputEn: 1| OutputEn: 0| OpenDrain: 0| Pullup: 1| Pulldown: 0| Intr:0
I (1756) wifi: n:11 0, o:1 0, ap:255 255, sta:11 0, prof:1
I (2736) wifi: state: init -> auth (b0)
I (2756) wifi: state: auth -> assoc (0)
I (2766) wifi: state: assoc -> run (10)
I (2786) wifi: connected with myssid, channel 11
I (2786) wifi: pm start, type: 1

I (4786) event: sta ip: 192.168.0.139, mask: 255.255.255.0, gw: 192.168.0.2
I (4786) mdns-test: Query A: tinytester.local
W (6876) mdns-test: ESP_ERR_NOT_FOUND: Host was not found!
I (6876) mdns-test: Query PTR: _tiny._tcp.local
W (9976) mdns-test: No results found!
I (21126) mdns-test: Query A: esp32.local
W (23176) mdns-test: ESP_ERR_NOT_FOUND: Host was not found!
I (23176) mdns-test: Query PTR: _arduino._tcp.local
W (26276) mdns-test: No results found!
I (26276) mdns-test: Query PTR: _http._tcp.local
1: Interface: STA, Type: V6
  PTR : HP Color LaserJet MFP M277dw (7C2E10)
  SRV : NPI7C2E10.local:80
  A   : 254.128.0.0
2: Interface: STA, Type: V4
  PTR : switch4e4919
  SRV : switch4e4919.local:80
  TXT : [1] path=/config/authentication_page.htm;
  A   : 192.168.0.118
I (29396) mdns-test: Query PTR: _printer._tcp.local
1: Interface: STA, Type: V6
  PTR : HP Color LaserJet MFP M277dw (7C2E10)
  SRV : NPI7C2E10.local:515
  A   : 254.128.0.0
2: Interface: STA, Type: V4
  PTR : HP Color LaserJet MFP M277dw (7C2E10)

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