Ethernet.setHostname added (hostname to send with DHCP request)

[JAndrassy]

There is already a PR for setHostname to set the hostname sent with the DHCP request and some older PR which don't use the setHostname() setter.

I provide my approach which doesn't store the hostname internally to save memory. I added the same code to my EthernetENC library. If setHostname is not used from the sketch the old code with the default hostname is executed.

overview of WiFi/Ethernet getters and setters:
https://github.com/JAndrassy/Arduino-Networking-API/blob/main/ArduinoNetAPILibs.md#network-interface-getters-and-setters

[github-actions]

Memory usage change @ 294063e

Board	flash	%	RAM for global variables	%
arduino:avr:leonardo	❔ -98 - +646	-0.34 - +2.25	💚 -102 - 0	-3.98 - 0.0
arduino:avr:mega	❔ -98 - +646	-0.04 - +0.25	💚 -102 - 0	-1.25 - 0.0
arduino:avr:nano	❔ -98 - +646	-0.32 - +2.1	💚 -102 - 0	-4.98 - 0.0
arduino:megaavr:nona4809	🔺 0 - +110	0.0 - +0.22	💚 -116 - 0	-1.89 - 0.0
arduino:megaavr:uno2018	🔺 0 - +110	0.0 - +0.23	💚 -116 - 0	-1.89 - 0.0
arduino:sam:arduino_due_x_dbg	🔺 0 - +48	0.0 - +0.01	N/A	N/A
arduino:samd:arduino_zero_edbg	🔺 0 - +40	0.0 - +0.02	💚 -112 - 0	-0.34 - 0.0
arduino:samd:mkr1000	🔺 0 - +40	0.0 - +0.02	💚 -112 - 0	-0.34 - 0.0
arduino:samd:mkrfox1200	🔺 0 - +40	0.0 - +0.02	💚 -112 - 0	-0.34 - 0.0
arduino:samd:mkrgsm1400	🔺 0 - +40	0.0 - +0.02	💚 -112 - 0	-0.34 - 0.0
arduino:samd:mkrnb1500	🔺 0 - +40	0.0 - +0.02	💚 -112 - 0	-0.34 - 0.0
arduino:samd:mkrvidor4000	🔺 0 - +40	0.0 - +0.02	💚 -112 - 0	-0.34 - 0.0
arduino:samd:mkrwan1300	🔺 0 - +40	0.0 - +0.02	💚 -112 - 0	-0.34 - 0.0
arduino:samd:mkrwan1310	🔺 0 - +40	0.0 - +0.02	💚 -112 - 0	-0.34 - 0.0
arduino:samd:mkrwifi1010	🔺 0 - +40	0.0 - +0.02	💚 -112 - 0	-0.34 - 0.0
arduino:samd:mkrzero	🔺 0 - +40	0.0 - +0.02	💚 -112 - 0	-0.34 - 0.0
arduino:samd:nano_33_iot	🔺 0 - +40	0.0 - +0.02	💚 -112 - 0	-0.34 - 0.0

Click for full report table

Board	examples/AdvancedChatServer flash	%	examples/AdvancedChatServer RAM for global variables	%	examples/BarometricPressureWebServer flash	%	examples/BarometricPressureWebServer RAM for global variables	%	examples/ChatServer flash	%	examples/ChatServer RAM for global variables	%	examples/DhcpAddressPrinter flash	%	examples/DhcpAddressPrinter RAM for global variables	%	examples/DhcpChatServer flash	%	examples/DhcpChatServer RAM for global variables	%	examples/LinkStatus flash	%	examples/LinkStatus RAM for global variables	%	examples/PagerServer flash	%	examples/PagerServer RAM for global variables	%	examples/TelnetClient flash	%	examples/TelnetClient RAM for global variables	%	examples/UDPSendReceiveString flash	%	examples/UDPSendReceiveString RAM for global variables	%	examples/UdpNtpClient flash	%	examples/UdpNtpClient RAM for global variables	%	examples/WebClient flash	%	examples/WebClient RAM for global variables	%	examples/WebClientRepeating flash	%	examples/WebClientRepeating RAM for global variables	%	examples/WebServer flash	%	examples/WebServer RAM for global variables	%
arduino:avr:leonardo	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	646	2.25	-92	-3.59	54	0.19	-102	-3.98	0	0.0	0	0.0	-98	-0.34	-102	-3.98	0	0.0	0	0.0	0	0.0	0	0.0	646	2.25	-92	-3.59	-62	-0.22	-102	-3.98	-98	-0.34	-102	-3.98	0	0.0	0	0.0
arduino:avr:mega	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	646	0.25	-92	-1.12	54	0.02	-102	-1.25	0	0.0	0	0.0	-98	-0.04	-102	-1.25	0	0.0	0	0.0	0	0.0	0	0.0	646	0.25	-92	-1.12	-62	-0.02	-102	-1.25	-96	-0.04	-102	-1.25	0	0.0	0	0.0
arduino:avr:nano	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	646	2.1	-92	-4.49	54	0.18	-102	-4.98	0	0.0	0	0.0	-98	-0.32	-102	-4.98	0	0.0	0	0.0	0	0.0	0	0.0	646	2.1	-92	-4.49	-62	-0.2	-102	-4.98	-96	-0.31	-102	-4.98	0	0.0	0	0.0
arduino:megaavr:nona4809	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	110	0.22	-116	-1.89	108	0.22	-116	-1.89	0	0.0	0	0.0	104	0.21	-116	-1.89	0	0.0	0	0.0	0	0.0	0	0.0	108	0.22	-116	-1.89	104	0.21	-116	-1.89	104	0.21	-116	-1.89	0	0.0	0	0.0
arduino:megaavr:uno2018	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	110	0.23	-116	-1.89	108	0.22	-116	-1.89	0	0.0	0	0.0	104	0.21	-116	-1.89	0	0.0	0	0.0	0	0.0	0	0.0	108	0.22	-116	-1.89	104	0.21	-116	-1.89	104	0.21	-116	-1.89	0	0.0	0	0.0
arduino:sam:arduino_due_x_dbg	0	0.0	N/A	N/A	0	0.0	N/A	N/A	0	0.0	N/A	N/A	40	0.01	N/A	N/A	48	0.01	N/A	N/A	0	0.0	N/A	N/A	40	0.01	N/A	N/A	0	0.0	N/A	N/A	0	0.0	N/A	N/A	48	0.01	N/A	N/A	40	0.01	N/A	N/A	40	0.01	N/A	N/A	0	0.0	N/A	N/A
arduino:samd:arduino_zero_edbg	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0	40	0.02	-112	-0.34	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0
arduino:samd:mkr1000	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0	40	0.02	-112	-0.34	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0
arduino:samd:mkrfox1200	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0	40	0.02	-112	-0.34	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0
arduino:samd:mkrgsm1400	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0	40	0.02	-112	-0.34	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0
arduino:samd:mkrnb1500	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0	40	0.02	-112	-0.34	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0
arduino:samd:mkrvidor4000	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0	40	0.02	-112	-0.34	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0
arduino:samd:mkrwan1300	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0	40	0.02	-112	-0.34	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0
arduino:samd:mkrwan1310	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0	40	0.02	-112	-0.34	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0
arduino:samd:mkrwifi1010	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0	40	0.02	-112	-0.34	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0
arduino:samd:mkrzero	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0	40	0.02	-112	-0.34	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0
arduino:samd:nano_33_iot	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0	40	0.02	-112	-0.34	0	0.0	0	0.0	0	0.0	0	0.0	40	0.02	-112	-0.34	40	0.02	-112	-0.34	40	0.02	-112	-0.34	0	0.0	0	0.0

Click for full report CSV

Board,examples/AdvancedChatServer<br>flash,%,examples/AdvancedChatServer<br>RAM for global variables,%,examples/BarometricPressureWebServer<br>flash,%,examples/BarometricPressureWebServer<br>RAM for global variables,%,examples/ChatServer<br>flash,%,examples/ChatServer<br>RAM for global variables,%,examples/DhcpAddressPrinter<br>flash,%,examples/DhcpAddressPrinter<br>RAM for global variables,%,examples/DhcpChatServer<br>flash,%,examples/DhcpChatServer<br>RAM for global variables,%,examples/LinkStatus<br>flash,%,examples/LinkStatus<br>RAM for global variables,%,examples/PagerServer<br>flash,%,examples/PagerServer<br>RAM for global variables,%,examples/TelnetClient<br>flash,%,examples/TelnetClient<br>RAM for global variables,%,examples/UDPSendReceiveString<br>flash,%,examples/UDPSendReceiveString<br>RAM for global variables,%,examples/UdpNtpClient<br>flash,%,examples/UdpNtpClient<br>RAM for global variables,%,examples/WebClient<br>flash,%,examples/WebClient<br>RAM for global variables,%,examples/WebClientRepeating<br>flash,%,examples/WebClientRepeating<br>RAM for global variables,%,examples/WebServer<br>flash,%,examples/WebServer<br>RAM for global variables,%
arduino:avr:leonardo,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,646,2.25,-92,-3.59,54,0.19,-102,-3.98,0,0.0,0,0.0,-98,-0.34,-102,-3.98,0,0.0,0,0.0,0,0.0,0,0.0,646,2.25,-92,-3.59,-62,-0.22,-102,-3.98,-98,-0.34,-102,-3.98,0,0.0,0,0.0
arduino:avr:mega,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,646,0.25,-92,-1.12,54,0.02,-102,-1.25,0,0.0,0,0.0,-98,-0.04,-102,-1.25,0,0.0,0,0.0,0,0.0,0,0.0,646,0.25,-92,-1.12,-62,-0.02,-102,-1.25,-96,-0.04,-102,-1.25,0,0.0,0,0.0
arduino:avr:nano,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,646,2.1,-92,-4.49,54,0.18,-102,-4.98,0,0.0,0,0.0,-98,-0.32,-102,-4.98,0,0.0,0,0.0,0,0.0,0,0.0,646,2.1,-92,-4.49,-62,-0.2,-102,-4.98,-96,-0.31,-102,-4.98,0,0.0,0,0.0
arduino:megaavr:nona4809,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,110,0.22,-116,-1.89,108,0.22,-116,-1.89,0,0.0,0,0.0,104,0.21,-116,-1.89,0,0.0,0,0.0,0,0.0,0,0.0,108,0.22,-116,-1.89,104,0.21,-116,-1.89,104,0.21,-116,-1.89,0,0.0,0,0.0
arduino:megaavr:uno2018,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,110,0.23,-116,-1.89,108,0.22,-116,-1.89,0,0.0,0,0.0,104,0.21,-116,-1.89,0,0.0,0,0.0,0,0.0,0,0.0,108,0.22,-116,-1.89,104,0.21,-116,-1.89,104,0.21,-116,-1.89,0,0.0,0,0.0
arduino:sam:arduino_due_x_dbg,0,0.0,N/A,N/A,0,0.0,N/A,N/A,0,0.0,N/A,N/A,40,0.01,N/A,N/A,48,0.01,N/A,N/A,0,0.0,N/A,N/A,40,0.01,N/A,N/A,0,0.0,N/A,N/A,0,0.0,N/A,N/A,48,0.01,N/A,N/A,40,0.01,N/A,N/A,40,0.01,N/A,N/A,0,0.0,N/A,N/A
arduino:samd:arduino_zero_edbg,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0,40,0.02,-112,-0.34,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0
arduino:samd:mkr1000,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0,40,0.02,-112,-0.34,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0
arduino:samd:mkrfox1200,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0,40,0.02,-112,-0.34,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0
arduino:samd:mkrgsm1400,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0,40,0.02,-112,-0.34,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0
arduino:samd:mkrnb1500,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0,40,0.02,-112,-0.34,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0
arduino:samd:mkrvidor4000,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0,40,0.02,-112,-0.34,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0
arduino:samd:mkrwan1300,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0,40,0.02,-112,-0.34,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0
arduino:samd:mkrwan1310,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0,40,0.02,-112,-0.34,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0
arduino:samd:mkrwifi1010,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0,40,0.02,-112,-0.34,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0
arduino:samd:mkrzero,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0,40,0.02,-112,-0.34,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0
arduino:samd:nano_33_iot,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0,40,0.02,-112,-0.34,0,0.0,0,0.0,0,0.0,0,0.0,40,0.02,-112,-0.34,40,0.02,-112,-0.34,40,0.02,-112,-0.34,0,0.0,0,0.0