c-ares

A C library for asynchronous DNS requests (grpc依赖)

Brad House ce9aa4807c Apple: reimplement DNS configuration reading (#750 ) The DNS configuration for apple is stored in the system configuration database. Apple does provide an emulated `/etc/resolv.conf` on MacOS (but not iOS), it cannot, however, represent the entirety of the DNS configuration. Alternatively, libresolv could be used to also retrieve some system configuration, but it too is not capable of retrieving the entirety of the DNS configuration. Attempts to use the preferred public API of `SCDynamicStoreCreate()` and friends yielded incomplete DNS information. Instead, that leaves some apple "internal" symbols from `configd` that we need to access in order to get the entire configuration. We can see that we're not the only ones to do this as Google Chrome also does: https://chromium.googlesource.com/chromium/src/+/HEAD/net/dns/dns_config_watcher_mac.cc These internal functions are what what`libresolv` and `scutil` use to retrieve the dns configuration. Since these symbols are not publicly available, we will dynamically load the symbols from `libSystem` and import the `dnsinfo.h` private header extracted from: https://opensource.apple.com/source/configd/configd-1109.140.1/dnsinfo/dnsinfo.h Fix By: Brad House (@bradh352)	7 months ago
..
dep5	Apple: reimplement DNS configuration reading (#750 )	7 months ago

Apple: reimplement DNS configuration reading (#750 )

The DNS configuration for apple is stored in the system configuration
database. Apple does provide an emulated `/etc/resolv.conf` on MacOS
(but not iOS), it cannot, however, represent the entirety of the DNS
configuration. Alternatively, libresolv could be used to also retrieve
some system configuration, but it too is not capable of retrieving the
entirety of the DNS configuration.

Attempts to use the preferred public API of `SCDynamicStoreCreate()` and
friends yielded incomplete DNS information. Instead, that leaves some
apple "internal" symbols from `configd` that we need to access in order
to get the entire configuration. We can see that we're not the only ones
to do this as Google Chrome also does:
https://chromium.googlesource.com/chromium/src/+/HEAD/net/dns/dns_config_watcher_mac.cc

These internal functions are what what`libresolv` and `scutil` use to
retrieve the dns configuration. Since these symbols are not publicly
available, we will dynamically load the symbols from `libSystem` and
import the `dnsinfo.h` private header extracted from:
https://opensource.apple.com/source/configd/configd-1109.140.1/dnsinfo/dnsinfo.h

Fix By: Brad House (@bradh352)

7 months ago

dep5

Apple: reimplement DNS configuration reading (#750 )

7 months ago