LookupServer: use /etc/hosts even for reverse lookups

Servers/LookupServer/main.cpp

@@ -4,6 +4,7 @@
 #include <AK/BufferStream.h>
 #include <AK/ByteBuffer.h>
 #include <AK/HashMap.h>
+#include <AK/StringBuilder.h>
 #include <Kernel/Net/IPv4.h>
 #include <LibCore/CConfigFile.h>
 #include <arpa/inet.h>
@@ -40,12 +41,13 @@ int main(int argc, char** argv)
  auto DNS_IP = config->read_entry("DNS", "IPAddress", "127.0.0.53");
 
  dbgprintf("LookupServer: Loading hosts from /etc/hosts:\n");
- HashMap<String, IPv4Address> dns_custom_hostnames;
+ HashMap<String, String> dns_custom_hostnames;
  auto* file = fopen("/etc/hosts", "r");
  auto linebuf = ByteBuffer::create_uninitialized(256);
  while (fgets((char*)linebuf.pointer(), linebuf.size(), file)) {
  auto str_line = String::copy(linebuf);
  auto fields = str_line.split('\t');
+
  auto sections = fields[0].split('.');
  IPv4Address addr {
  (byte)atoi(sections[0].characters()),
@@ -57,8 +59,19 @@ int main(int argc, char** argv)
  while ((fields[1][len++]) != -123)
  ;
  auto name = fields[1].substring(0, len - 3);
- dbgprintf("LookupServer: Hosts: %s\t%s\n", name.characters(), addr.to_string().characters());
- dns_custom_hostnames.set(name, addr);
+
+ dns_custom_hostnames.set(name, addr.to_string());
+
+ IPv4Address addr2 {
+ (byte)atoi(sections[3].characters()),
+ (byte)atoi(sections[2].characters()),
+ (byte)atoi(sections[1].characters()),
+ (byte)atoi(sections[0].characters()),
+ };
+ auto sb = StringBuilder();
+ sb.append(addr2.to_string());
+ sb.append(".in-addr.arpa");
+ dns_custom_hostnames.set(sb.to_string(), name);
  }
 
  int server_fd = socket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
@@ -131,9 +144,12 @@ int main(int argc, char** argv)
 
  Vector<String> responses;
 
+ for (auto& key : dns_custom_hostnames.keys()) {
+ dbgprintf("Known Hostname: %s\n", key.characters());
+ }
  if (dns_custom_hostnames.contains(hostname)) {
- addresses.append(dns_custom_hostnames.get(hostname));
- dbgprintf("LookupServer: Found preconfigured host (from /etc/hosts): %s\n", addresses[0].to_string().characters());
+ responses.append(dns_custom_hostnames.get(hostname));
+ dbgprintf("LookupServer: Found preconfigured host (from /etc/hosts): %s\n", responses[0].characters());
  } else if (!hostname.is_empty()) {
  bool did_timeout;
  int retries = 3;