feat: impl dns.getServers

[Hanaasagi]

Close: #3981

What does this PR do?

• Implement the dns.getServers function

Reference:

• https://nodejs.org/api/dns.html#dnsgetservers
• https://c-ares.org/ares_get_servers_ports.html

• Documentation or TypeScript types (it's okay to leave the rest blank in this case)
• Code changes

How did you verify your code works?

I wrote automated tests

• I ran make js and committed the transpiled changes

• I or my editor ran Prettier on the changed files (or I ran bun fmt)

• I included a test for the new code, or an existing test covers it

• I checked the lifetime of memory allocated to verify it's (1) freed and (2) only freed when it should be

• I or my editor ran zig fmt on the changed files

• I included a test for the new code, or an existing test covers it

• JSValue used outside outside of the stack is either wrapped in a JSC.Strong or is JSValueProtect'ed

[Jarred-Sumner]

nice

[Jarred-Sumner]

I think this test will only work on linux

can use test.skipIf(process.platform === “darwin”)

[Jarred-Sumner]

Thank you. This looks good. Let’s let the tests run.

Only part I’m not sure about is the buffer length. If any of the numbers are not 100% correct in all the cases it could cause a crash or undefined behavior and it’d be hard to reproduce.

Assuming the current length isn’t huge (like 64 bytes probably), I suggest adding an extra 512 bytes to it just for wiggle room

[Hanaasagi]

About the buffer length, I checked the source code of ares_inet_ntop. It checks the size parameter we pass in, so overflow should not occur. However, I think I should handle the case where the return value is NULL.

https://github.com/c-ares/c-ares/blob/bad62225b7f6b278b92e8e85a255600b629ef517/src/lib/inet_ntop.c#L58-L95

And std.fmt.bufPrint will also check buf length.

https://github.com/ziglang/zig/blob/fc6e5756848cd627b69756853937ce22500e62cc/lib/std/fmt.zig#L1996
https://github.com/ziglang/zig/blob/fc6e5756848cd627b69756853937ce22500e62cc/lib/std/io/fixed_buffer_stream.zig#L63

[Jarred-Sumner]

About the buffer length, I checked the source code of ares_inet_ntop. It checks the size parameter we pass in, so overflow should not occur. However, I think I should handle the case where the return value is NULL.

https://github.com/c-ares/c-ares/blob/bad62225b7f6b278b92e8e85a255600b629ef517/src/lib/inet_ntop.c#L58-L95

And std.fmt.bufPrint will also check buf length.

https://github.com/ziglang/zig/blob/fc6e5756848cd627b69756853937ce22500e62cc/lib/std/fmt.zig#L1996 https://github.com/ziglang/zig/blob/fc6e5756848cd627b69756853937ce22500e62cc/lib/std/io/fixed_buffer_stream.zig#L63

👍