[Lldb-commits] [lldb] [lldb] Fix the SocketTest failure on unsupported hosts (PR #118673)

[Vladislav Dzhidzhoev via lldb-commits]

================
@@ -116,6 +116,24 @@ bool lldb_private::HostSupportsIPv6() {
   return CheckIPSupport("IPv6", "[::1]:0");
 }
 
+bool lldb_private::HostSupportsLocalhostToIPv4() {
+  if (!HostSupportsIPv4())
+    return false;
+
+  auto addresses = SocketAddress::GetAddressInfo("localhost", nullptr, AF_INET,
+                                                 SOCK_STREAM, IPPROTO_TCP);
+  return !addresses.empty();
+}
+
+bool lldb_private::HostSupportsLocalhostToIPv6() {
+  if (!HostSupportsIPv6())
+    return false;
+
+  auto addresses = SocketAddress::GetAddressInfo("localhost", nullptr, AF_INET6,
+                                                 SOCK_STREAM, IPPROTO_TCP);
----------------
dzhidzhoev wrote:

I've got 
```
llvm-project git:(becab1c1b0a3) cat /etc/hosts     
127.0.0.1 localhost
127.0.1.1 ubuntu-linux-22-04-desktop

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

```

For some reason, `getaddrinfo("localhost", AF_UNSPEC, ...)` returns only one address (IPv4 `127.0.0.1`), but `getaddrinfo("localhost", AF_INET6, ...)` returns an address as well (IPv6 `::1`).

I think it's probably an oddity in getaddrinfo implementation (my gai.conf is empty). This check seems to work the way expected:

```
auto addresses = SocketAddress::GetAddressInfo(
    "localhost", nullptr, AF_UNSPEC, SOCK_STREAM, IPPROTO_TCP);
return std::find_if(addresses.begin(), addresses.end(),
                    [](SocketAddress &addr) {
                      return addr.GetFamily() == AF_INET6;
                    }) != addresses.end();

```


https://github.com/llvm/llvm-project/pull/118673