DNSClient::inet_aton fix and new IPAddress::fromString method

[cmaglie]

• fixed a parsing bug in DNSClient::inet_aton as reported in Bugfix DNSClient::getHostByName() #2500 (the solution proposed in Bugfix DNSClient::getHostByName() #2500 is only a partial fix)
• Since it's not DNS related, the same functionality has been added to IPAddress.

At this point DNSClient::inet_aton can be transformed to just an inline call to IPAddress::fromString but this will make the Ethernet library incompatible with old cores, so the temporary compromise is that the code is duplicated until the new core becomes more widespread.

[jhorck]

I proposed #2500. This fix looks good to me too, though I didn't test it.

I don't understand the comment "// TODO: add support for "a", "a.b", "a.b.c" formats"
IP addresses always have 4 bytes (IPv4). I hope fewer bytes are NEVER accepted as a valid IP address?

[ArduinoBot]

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http://downloads.arduino.cc/javaide/pull_requests/arduino-PR-3780-BUILD-393-macosx.zip

[cmaglie]

Hi @jhorck

thanks for the comment.

I don't understand the comment "// TODO: add support for "a", "a.b", "a.b.c" formats"

believe it or not you can specify the ip address using the following format:

A.A.A.A
A.A.B
A.C
D

where:

• A is an 8-bit unsigned
• B is a 16-bit unsigned
• C is a 24-bit unsigned
• D is a 32-bit unsigned

for example on my linux box I can do:

:~$ ping 2130706433
PING 2130706433 (127.0.0.1) 56(84) bytes of data.
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.056 ms

or better.

~$ ping 127.1
PING 127.1 (127.0.0.1) 56(84) bytes of data.
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.043 ms

I didn't know that until I looked to some implementations of inet_aton (for example http://www.comp.nus.edu.sg/~cs3223/doxygen-postgres9.4.0/html/dd/dbe/inet__aton_8c_source.html)

BTW it's a so rarely used feature that I guess we'll leave it unsupported.

[jhorck]

@cmaglie, You're right! I didn't know that!