Implement SSL service

This implements some missing network APIs including a large chunk of the SSL
service, enough for Mario Maker (with an appropriate mod applied) to connect to
the fan server [Open Course World](https://opencourse.world/).

Connecting to first-party servers is out of scope of this PR and is a
minefield I'd rather not step into.

 ## TLS

TLS is implemented with multiple backends depending on the system's 'native'
TLS library.  Currently there are two backends: Schannel for Windows, and
OpenSSL for Linux.  (In reality Linux is a bit of a free-for-all where there's
no one 'native' library, but OpenSSL is the closest it gets.)  On macOS the
'native' library is SecureTransport but that isn't implemented in this PR.
(Instead, all non-Windows OSes will use OpenSSL unless disabled with
`-DENABLE_OPENSSL=OFF`.)

Why have multiple backends instead of just using a single library, especially
given that Yuzu already embeds mbedtls for cryptographic algorithms?  Well, I
tried implementing this on mbedtls first, but the problem is TLS policies -
mainly trusted certificate policies, and to a lesser extent trusted algorithms,
SSL versions, etc.

...In practice, the chance that someone is going to conduct a man-in-the-middle
attack on a third-party game server is pretty low, but I'm a security nerd so I
like to do the right security things.

My base assumption is that we want to use the host system's TLS policies.  An
alternative would be to more closely emulate the Switch's TLS implementation
(which is based on NSS).  But for one thing, I don't feel like reverse
engineering it.  And I'd argue that for third-party servers such as Open Course
World, it's theoretically preferable to use the system's policies rather than
the Switch's, for two reasons

1. Someday the Switch will stop being updated, and the trusted cert list,
   algorithms, etc. will start to go stale, but users will still want to
   connect to third-party servers, and there's no reason they shouldn't have
   up-to-date security when doing so.  At that point, homebrew users on actual
   hardware may patch the TLS implementation, but for emulators it's simpler to
   just use the host's stack.

2. Also, it's good to respect any custom certificate policies the user may have
   added systemwide.  For example, they may have added custom trusted CAs in
   order to use TLS debugging tools or pass through corporate MitM middleboxes.
   Or they may have removed some CAs that are normally trusted out of paranoia.

Note that this policy wouldn't work as-is for connecting to first-party
servers, because some of them serve certificates based on Nintendo's own CA
rather than a publicly trusted one.  However, this could probably be solved
easily by using appropriate APIs to adding Nintendo's CA as an alternate
trusted cert for Yuzu's connections.  That is not implemented in this PR
because, again, first-party servers are out of scope.

(If anything I'd rather have an option to _block_ connections to Nintendo
servers, but that's not implemented here.)

To use the host's TLS policies, there are three theoretical options:

a) Import the host's trusted certificate list into a cross-platform TLS
   library (presumably mbedtls).

b) Use the native TLS library to verify certificates but use a cross-platform
   TLS library for everything else.

c) Use the native TLS library for everything.

Two problems with option a).  First, importing the trusted certificate list at
minimum requires a bunch of platform-specific code, which mbedtls does not have
built in.  Interestingly, OpenSSL recently gained the ability to import the
Windows certificate trust store... but that leads to the second problem, which
is that a list of trusted certificates is [not expressive
enough](https://bugs.archlinux.org/task/41909) to express a modern certificate
trust policy.  For example, Windows has the concept of [explicitly distrusted
certificates](https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-r2-and-2012/dn265983(v=ws.11)),
and macOS requires Certificate Transparency validation for some certificates
with complex rules for when it's required.

Option b) (using native library just to verify certs) is probably feasible, but
it would miss aspects of TLS policy other than trusted certs (like allowed
algorithms), and in any case it might well require writing more code, not less,
compared to using the native library for everything.

So I ended up at option c), using the native library for everything.

What I'd *really* prefer would be to use a third-party library that does option
c) for me.  Rust has a good library for this,
[native-tls](https://docs.rs/native-tls/latest/native_tls/).  I did search, but
I couldn't find a good option in the C or C++ ecosystem, at least not any that
wasn't part of some much larger framework.  I was surprised - isn't this a
pretty common use case?  Well, many applications only need TLS for HTTPS, and they can
use libcurl, which has a TLS abstraction layer internally but doesn't expose
it.  Other applications only support a single TLS library, or use one of the
aforementioned larger frameworks, or are platform-specific to begin with, or of
course are written in a non-C/C++ language, most of which have some canonical
choice for TLS.  But there are also many applications that have a set of TLS
backends just like this; it's just that nobody has gone ahead and abstracted
the pattern into a library, at least not a widespread one.

Amusingly, there is one TLS abstraction layer that Yuzu already bundles: the
one in ffmpeg.  But it is missing some features that would be needed to use it
here (like reusing an existing socket rather than managing the socket itself).
Though, that does mean that the wiki's build instructions for Linux (and macOS
for some reason?) already recommend installing OpenSSL, so no need to update
those.

 ## Other APIs implemented

- Sockets:
    - GetSockOpt(`SO_ERROR`)
    - SetSockOpt(`SO_NOSIGPIPE`) (stub, I have no idea what this does on Switch)
    - `DuplicateSocket` (because the SSL sysmodule calls it internally)
    - More `PollEvents` values

- NSD:
    - `Resolve` and `ResolveEx` (stub, good enough for Open Course World and
      probably most third-party servers, but not first-party)

- SFDNSRES:
    - `GetHostByNameRequest` and `GetHostByNameRequestWithOptions`
    - `ResolverSetOptionRequest` (stub)

 ## Fixes

- Parts of the socket code were previously allocating a `sockaddr` object on
  the stack when calling functions that take a `sockaddr*` (e.g. `accept`).
  This might seem like the right thing to do to avoid illegal aliasing, but in
  fact `sockaddr` is not guaranteed to be large enough to hold any particular
  type of address, only the header.  This worked in practice because in
  practice `sockaddr` is the same size as `sockaddr_in`, but it's not how the
  API is meant to be used.  I changed this to allocate an `sockaddr_in` on the
  stack and `reinterpret_cast` it.  I could try to do something cleverer with
  `aligned_storage`, but casting is the idiomatic way to use these particular
  APIs, so it's really the system's responsibility to avoid any aliasing
  issues.

- I rewrote most of the `GetAddrInfoRequest[WithOptions]` implementation.  The
  old implementation invoked the host's getaddrinfo directly from sfdnsres.cpp,
  and directly passed through the host's socket type, protocol, etc. values
  rather than looking up the corresponding constants on the Switch.  To be
  fair, these constants don't tend to actually vary across systems, but
  still... I added a wrapper for `getaddrinfo` in
  `internal_network/network.cpp` similar to the ones for other socket APIs, and
  changed the `GetAddrInfoRequest` implementation to use it.  While I was at
  it, I rewrote the serialization to use the same approach I used to implement
  `GetHostByNameRequest`, because it reduces the number of size calculations.
  While doing so I removed `AF_INET6` support because the Switch doesn't
  support IPv6; it might be nice to support IPv6 anyway, but that would have to
  apply to all of the socket APIs.

  I also corrected the IPC wrappers for `GetAddrInfoRequest` and
  `GetAddrInfoRequestWithOptions` based on reverse engineering and hardware
  testing.  Every call to `GetAddrInfoRequestWithOptions` returns *four*
  different error codes (IPC status, getaddrinfo error code, netdb error code,
  and errno), and `GetAddrInfoRequest` returns three of those but in a
  different order, and it doesn't really matter but the existing implementation
  was a bit off, as I discovered while testing `GetHostByNameRequest`.

  - The new serialization code is based on two simple helper functions:

    ```cpp
    template <typename T> static void Append(std::vector<u8>& vec, T t);
    void AppendNulTerminated(std::vector<u8>& vec, std::string_view str);
    ```

    I was thinking there must be existing functions somewhere that assist with
    serialization/deserialization of binary data, but all I could find was the
    helper methods in `IOFile` and `HLERequestContext`, not anything that could
    be used with a generic byte buffer.  If I'm not missing something, then
    maybe I should move the above functions to a new header in `common`...
    right now they're just sitting in `sfdnsres.cpp` where they're used.

- Not a fix, but `SocketBase::Recv`/`Send` is changed to use `std::span<u8>`
  rather than `std::vector<u8>&` to avoid needing to copy the data to/from a
  vector when those methods are called from the TLS implementation.

5 files changed, 281 insertions, 73 deletions

diff --git a/src/core/internal_network/network.cpp b/src/core/internal_network/network.cpp
index 75ac10a9c..39381e06e 100644
--- a/src/core/internal_network/network.cpp
+++ b/src/core/internal_network/network.cpp
@@ -121,6 +121,8 @@ Errno TranslateNativeError(int e) {
         return Errno::MSGSIZE;
     case WSAETIMEDOUT:
         return Errno::TIMEDOUT;
+    case WSAEINPROGRESS:
+        return Errno::INPROGRESS;
     default:
         UNIMPLEMENTED_MSG("Unimplemented errno={}", e);
         return Errno::OTHER;
@@ -195,6 +197,8 @@ bool EnableNonBlock(int fd, bool enable) {
 
 Errno TranslateNativeError(int e) {
     switch (e) {
+    case 0:
+        return Errno::SUCCESS;
     case EBADF:
         return Errno::BADF;
     case EINVAL:
@@ -219,8 +223,10 @@ Errno TranslateNativeError(int e) {
         return Errno::MSGSIZE;
     case ETIMEDOUT:
         return Errno::TIMEDOUT;
+    case EINPROGRESS:
+        return Errno::INPROGRESS;
     default:
-        UNIMPLEMENTED_MSG("Unimplemented errno={}", e);
+        UNIMPLEMENTED_MSG("Unimplemented errno={} ({})", e, strerror(e));
         return Errno::OTHER;
     }
 }
@@ -234,15 +240,84 @@ Errno GetAndLogLastError() {
     int e = errno;
 #endif
     const Errno err = TranslateNativeError(e);
-    if (err == Errno::AGAIN || err == Errno::TIMEDOUT) {
+    if (err == Errno::AGAIN || err == Errno::TIMEDOUT || err == Errno::INPROGRESS) {
+        // These happen during normal operation, so only log them at debug level.
+        LOG_DEBUG(Network, "Socket operation error: {}", Common::NativeErrorToString(e));
         return err;
     }
     LOG_ERROR(Network, "Socket operation error: {}", Common::NativeErrorToString(e));
     return err;
 }
 
-int TranslateDomain(Domain domain) {
+GetAddrInfoError TranslateGetAddrInfoErrorFromNative(int gai_err) {
+    switch (gai_err) {
+    case 0:
+        return GetAddrInfoError::SUCCESS;
+#ifdef EAI_ADDRFAMILY
+    case EAI_ADDRFAMILY:
+        return GetAddrInfoError::ADDRFAMILY;
+#endif
+    case EAI_AGAIN:
+        return GetAddrInfoError::AGAIN;
+    case EAI_BADFLAGS:
+        return GetAddrInfoError::BADFLAGS;
+    case EAI_FAIL:
+        return GetAddrInfoError::FAIL;
+    case EAI_FAMILY:
+        return GetAddrInfoError::FAMILY;
+    case EAI_MEMORY:
+        return GetAddrInfoError::MEMORY;
+    case EAI_NONAME:
+        return GetAddrInfoError::NONAME;
+    case EAI_SERVICE:
+        return GetAddrInfoError::SERVICE;
+    case EAI_SOCKTYPE:
+        return GetAddrInfoError::SOCKTYPE;
+        // These codes may not be defined on all systems:
+#ifdef EAI_SYSTEM
+    case EAI_SYSTEM:
+        return GetAddrInfoError::SYSTEM;
+#endif
+#ifdef EAI_BADHINTS
+    case EAI_BADHINTS:
+        return GetAddrInfoError::BADHINTS;
+#endif
+#ifdef EAI_PROTOCOL
+    case EAI_PROTOCOL:
+        return GetAddrInfoError::PROTOCOL;
+#endif
+#ifdef EAI_OVERFLOW
+    case EAI_OVERFLOW:
+        return GetAddrInfoError::OVERFLOW_;
+#endif
+    default:
+#ifdef EAI_NODATA
+        // This can't be a case statement because it would create a duplicate
+        // case on Windows where EAI_NODATA is an alias for EAI_NONAME.
+        if (gai_err == EAI_NODATA) {
+            return GetAddrInfoError::NODATA;
+        }
+#endif
+        return GetAddrInfoError::OTHER;
+    }
+}
+
+Domain TranslateDomainFromNative(int domain) {
     switch (domain) {
+    case 0:
+        return Domain::Unspecified;
+    case AF_INET:
+        return Domain::INET;
+    default:
+        UNIMPLEMENTED_MSG("Unhandled domain={}", domain);
+        return Domain::INET;
+    }
+}
+
+int TranslateDomainToNative(Domain domain) {
+    switch (domain) {
+    case Domain::Unspecified:
+        return 0;
     case Domain::INET:
         return AF_INET;
     default:
@@ -251,20 +326,58 @@ int TranslateDomain(Domain domain) {
     }
 }
 
-int TranslateType(Type type) {
+Type TranslateTypeFromNative(int type) {
+    switch (type) {
+    case 0:
+        return Type::Unspecified;
+    case SOCK_STREAM:
+        return Type::STREAM;
+    case SOCK_DGRAM:
+        return Type::DGRAM;
+    case SOCK_RAW:
+        return Type::RAW;
+    case SOCK_SEQPACKET:
+        return Type::SEQPACKET;
+    default:
+        UNIMPLEMENTED_MSG("Unimplemented type={}", type);
+        return Type::STREAM;
+    }
+}
+
+int TranslateTypeToNative(Type type) {
     switch (type) {
+    case Type::Unspecified:
+        return 0;
     case Type::STREAM:
         return SOCK_STREAM;
     case Type::DGRAM:
         return SOCK_DGRAM;
+    case Type::RAW:
+        return SOCK_RAW;
     default:
         UNIMPLEMENTED_MSG("Unimplemented type={}", type);
         return 0;
     }
 }
 
-int TranslateProtocol(Protocol protocol) {
+Protocol TranslateProtocolFromNative(int protocol) {
+    switch (protocol) {
+    case 0:
+        return Protocol::Unspecified;
+    case IPPROTO_TCP:
+        return Protocol::TCP;
+    case IPPROTO_UDP:
+        return Protocol::UDP;
+    default:
+        UNIMPLEMENTED_MSG("Unimplemented protocol={}", protocol);
+        return Protocol::Unspecified;
+    }
+}
+
+int TranslateProtocolToNative(Protocol protocol) {
     switch (protocol) {
+    case Protocol::Unspecified:
+        return 0;
     case Protocol::TCP:
         return IPPROTO_TCP;
     case Protocol::UDP:
@@ -275,21 +388,10 @@ int TranslateProtocol(Protocol protocol) {
     }
 }
 
-SockAddrIn TranslateToSockAddrIn(sockaddr input_) {
-    sockaddr_in input;
-    std::memcpy(&input, &input_, sizeof(input));
-
+SockAddrIn TranslateToSockAddrIn(sockaddr_in input, size_t input_len) {
     SockAddrIn result;
 
-    switch (input.sin_family) {
-    case AF_INET:
-        result.family = Domain::INET;
-        break;
-    default:
-        UNIMPLEMENTED_MSG("Unhandled sockaddr family={}", input.sin_family);
-        result.family = Domain::INET;
-        break;
-    }
+    result.family = TranslateDomainFromNative(input.sin_family);
 
     result.portno = ntohs(input.sin_port);
 
@@ -301,22 +403,28 @@ SockAddrIn TranslateToSockAddrIn(sockaddr input_) {
 short TranslatePollEvents(PollEvents events) {
     short result = 0;
 
-    if (True(events & PollEvents::In)) {
-        events &= ~PollEvents::In;
-        result |= POLLIN;
-    }
-    if (True(events & PollEvents::Pri)) {
-        events &= ~PollEvents::Pri;
+    const auto translate = [&result, &events](PollEvents guest, short host) {
+        if (True(events & guest)) {
+            events &= ~guest;
+            result |= host;
+        }
+    };
+
+    translate(PollEvents::In, POLLIN);
+    translate(PollEvents::Pri, POLLPRI);
+    translate(PollEvents::Out, POLLOUT);
+    translate(PollEvents::Err, POLLERR);
+    translate(PollEvents::Hup, POLLHUP);
+    translate(PollEvents::Nval, POLLNVAL);
+    translate(PollEvents::RdNorm, POLLRDNORM);
+    translate(PollEvents::RdBand, POLLRDBAND);
+    translate(PollEvents::WrBand, POLLWRBAND);
+
 #ifdef _WIN32
+    if (True(events & PollEvents::Pri)) {
         LOG_WARNING(Service, "Winsock doesn't support POLLPRI");
-#else
-        result |= POLLPRI;
-#endif
-    }
-    if (True(events & PollEvents::Out)) {
-        events &= ~PollEvents::Out;
-        result |= POLLOUT;
     }
+#endif
 
     UNIMPLEMENTED_IF_MSG((u16)events != 0, "Unhandled guest events=0x{:x}", (u16)events);
 
@@ -337,6 +445,10 @@ PollEvents TranslatePollRevents(short revents) {
     translate(POLLOUT, PollEvents::Out);
     translate(POLLERR, PollEvents::Err);
     translate(POLLHUP, PollEvents::Hup);
+    translate(POLLNVAL, PollEvents::Nval);
+    translate(POLLRDNORM, PollEvents::RdNorm);
+    translate(POLLRDBAND, PollEvents::RdBand);
+    translate(POLLWRBAND, PollEvents::WrBand);
 
     UNIMPLEMENTED_IF_MSG(revents != 0, "Unhandled host revents=0x{:x}", revents);
 
@@ -360,12 +472,53 @@ std::optional<IPv4Address> GetHostIPv4Address() {
         return {};
     }
 
-    std::array<char, 16> ip_addr = {};
-    ASSERT(inet_ntop(AF_INET, &network_interface->ip_address, ip_addr.data(), sizeof(ip_addr)) !=
-           nullptr);
     return TranslateIPv4(network_interface->ip_address);
 }
 
+std::string IPv4AddressToString(IPv4Address ip_addr) {
+    std::array<char, INET_ADDRSTRLEN> buf = {};
+    ASSERT(inet_ntop(AF_INET, &ip_addr, buf.data(), sizeof(buf)) == buf.data());
+    return std::string(buf.data());
+}
+
+u32 IPv4AddressToInteger(IPv4Address ip_addr) {
+    return static_cast<u32>(ip_addr[0]) << 24 | static_cast<u32>(ip_addr[1]) << 16 |
+           static_cast<u32>(ip_addr[2]) << 8 | static_cast<u32>(ip_addr[3]);
+}
+
+#undef GetAddrInfo // Windows defines it as a macro
+
+Common::Expected<std::vector<AddrInfo>, GetAddrInfoError> GetAddrInfo(
+    const std::string& host, const std::optional<std::string>& service) {
+    addrinfo hints{};
+    hints.ai_family = AF_INET; // Switch only supports IPv4.
+    addrinfo* addrinfo;
+    s32 gai_err = getaddrinfo(host.c_str(), service.has_value() ? service->c_str() : nullptr,
+                              &hints, &addrinfo);
+    if (gai_err != 0) {
+        return Common::Unexpected(TranslateGetAddrInfoErrorFromNative(gai_err));
+    }
+    std::vector<AddrInfo> ret;
+    for (auto* current = addrinfo; current; current = current->ai_next) {
+        // We should only get AF_INET results due to the hints value.
+        ASSERT_OR_EXECUTE(addrinfo->ai_family == AF_INET &&
+                              addrinfo->ai_addrlen == sizeof(sockaddr_in),
+                          continue;);
+
+        AddrInfo& out = ret.emplace_back();
+        out.family = TranslateDomainFromNative(current->ai_family);
+        out.socket_type = TranslateTypeFromNative(current->ai_socktype);
+        out.protocol = TranslateProtocolFromNative(current->ai_protocol);
+        out.addr = TranslateToSockAddrIn(*reinterpret_cast<sockaddr_in*>(current->ai_addr),
+                                         current->ai_addrlen);
+        if (current->ai_canonname != nullptr) {
+            out.canon_name = current->ai_canonname;
+        }
+    }
+    freeaddrinfo(addrinfo);
+    return ret;
+}
+
 std::pair<s32, Errno> Poll(std::vector<PollFD>& pollfds, s32 timeout) {
     const size_t num = pollfds.size();
 
@@ -411,6 +564,18 @@ Socket::Socket(Socket&& rhs) noexcept {
 }
 
 template <typename T>
+std::pair<T, Errno> Socket::GetSockOpt(SOCKET fd_, int option) {
+    T value{};
+    socklen_t len = sizeof(value);
+    const int result = getsockopt(fd_, SOL_SOCKET, option, reinterpret_cast<char*>(&value), &len);
+    if (result != SOCKET_ERROR) {
+        ASSERT(len == sizeof(value));
+        return {value, Errno::SUCCESS};
+    }
+    return {value, GetAndLogLastError()};
+}
+
+template <typename T>
 Errno Socket::SetSockOpt(SOCKET fd_, int option, T value) {
     const int result =
         setsockopt(fd_, SOL_SOCKET, option, reinterpret_cast<const char*>(&value), sizeof(value));
@@ -421,7 +586,8 @@ Errno Socket::SetSockOpt(SOCKET fd_, int option, T value) {
 }
 
 Errno Socket::Initialize(Domain domain, Type type, Protocol protocol) {
-    fd = socket(TranslateDomain(domain), TranslateType(type), TranslateProtocol(protocol));
+    fd = socket(TranslateDomainToNative(domain), TranslateTypeToNative(type),
+                TranslateProtocolToNative(protocol));
     if (fd != INVALID_SOCKET) {
         return Errno::SUCCESS;
     }
@@ -430,19 +596,17 @@ Errno Socket::Initialize(Domain domain, Type type, Protocol protocol) {
 }
 
 std::pair<SocketBase::AcceptResult, Errno> Socket::Accept() {
-    sockaddr addr;
+    sockaddr_in addr;
     socklen_t addrlen = sizeof(addr);
-    const SOCKET new_socket = accept(fd, &addr, &addrlen);
+    const SOCKET new_socket = accept(fd, reinterpret_cast<sockaddr*>(&addr), &addrlen);
 
     if (new_socket == INVALID_SOCKET) {
         return {AcceptResult{}, GetAndLogLastError()};
     }
 
-    ASSERT(addrlen == sizeof(sockaddr_in));
-
     AcceptResult result{
         .socket = std::make_unique<Socket>(new_socket),
-        .sockaddr_in = TranslateToSockAddrIn(addr),
+        .sockaddr_in = TranslateToSockAddrIn(addr, addrlen),
     };
 
     return {std::move(result), Errno::SUCCESS};
@@ -458,25 +622,23 @@ Errno Socket::Connect(SockAddrIn addr_in) {
 }
 
 std::pair<SockAddrIn, Errno> Socket::GetPeerName() {
-    sockaddr addr;
+    sockaddr_in addr;
     socklen_t addrlen = sizeof(addr);
-    if (getpeername(fd, &addr, &addrlen) == SOCKET_ERROR) {
+    if (getpeername(fd, reinterpret_cast<sockaddr*>(&addr), &addrlen) == SOCKET_ERROR) {
         return {SockAddrIn{}, GetAndLogLastError()};
     }
 
-    ASSERT(addrlen == sizeof(sockaddr_in));
-    return {TranslateToSockAddrIn(addr), Errno::SUCCESS};
+    return {TranslateToSockAddrIn(addr, addrlen), Errno::SUCCESS};
 }
 
 std::pair<SockAddrIn, Errno> Socket::GetSockName() {
-    sockaddr addr;
+    sockaddr_in addr;
     socklen_t addrlen = sizeof(addr);
-    if (getsockname(fd, &addr, &addrlen) == SOCKET_ERROR) {
+    if (getsockname(fd, reinterpret_cast<sockaddr*>(&addr), &addrlen) == SOCKET_ERROR) {
         return {SockAddrIn{}, GetAndLogLastError()};
     }
 
-    ASSERT(addrlen == sizeof(sockaddr_in));
-    return {TranslateToSockAddrIn(addr), Errno::SUCCESS};
+    return {TranslateToSockAddrIn(addr, addrlen), Errno::SUCCESS};
 }
 
 Errno Socket::Bind(SockAddrIn addr) {
@@ -519,7 +681,7 @@ Errno Socket::Shutdown(ShutdownHow how) {
     return GetAndLogLastError();
 }
 
-std::pair<s32, Errno> Socket::Recv(int flags, std::vector<u8>& message) {
+std::pair<s32, Errno> Socket::Recv(int flags, std::span<u8> message) {
     ASSERT(flags == 0);
     ASSERT(message.size() < static_cast<size_t>(std::numeric_limits<int>::max()));
 
@@ -532,21 +694,20 @@ std::pair<s32, Errno> Socket::Recv(int flags, std::vector<u8>& message) {
     return {-1, GetAndLogLastError()};
 }
 
-std::pair<s32, Errno> Socket::RecvFrom(int flags, std::vector<u8>& message, SockAddrIn* addr) {
+std::pair<s32, Errno> Socket::RecvFrom(int flags, std::span<u8> message, SockAddrIn* addr) {
     ASSERT(flags == 0);
     ASSERT(message.size() < static_cast<size_t>(std::numeric_limits<int>::max()));
 
-    sockaddr addr_in{};
+    sockaddr_in addr_in{};
     socklen_t addrlen = sizeof(addr_in);
     socklen_t* const p_addrlen = addr ? &addrlen : nullptr;
-    sockaddr* const p_addr_in = addr ? &addr_in : nullptr;
+    sockaddr* const p_addr_in = addr ? reinterpret_cast<sockaddr*>(&addr_in) : nullptr;
 
     const auto result = recvfrom(fd, reinterpret_cast<char*>(message.data()),
                                  static_cast<int>(message.size()), 0, p_addr_in, p_addrlen);
     if (result != SOCKET_ERROR) {
         if (addr) {
-            ASSERT(addrlen == sizeof(addr_in));
-            *addr = TranslateToSockAddrIn(addr_in);
+            *addr = TranslateToSockAddrIn(addr_in, addrlen);
         }
         return {static_cast<s32>(result), Errno::SUCCESS};
     }
@@ -597,6 +758,11 @@ Errno Socket::Close() {
     return Errno::SUCCESS;
 }
 
+std::pair<Errno, Errno> Socket::GetPendingError() {
+    auto [pending_err, getsockopt_err] = GetSockOpt<int>(fd, SO_ERROR);
+    return {TranslateNativeError(pending_err), getsockopt_err};
+}
+
 Errno Socket::SetLinger(bool enable, u32 linger) {
     return SetSockOpt(fd, SO_LINGER, MakeLinger(enable, linger));
 }
diff --git a/src/core/internal_network/network.h b/src/core/internal_network/network.h
index 1e09a007a..96319bfc8 100644
--- a/src/core/internal_network/network.h
+++ b/src/core/internal_network/network.h
@@ -16,6 +16,11 @@
 #include <netinet/in.h>
 #endif
 
+namespace Common {
+template <typename T, typename E>
+class Expected;
+}
+
 namespace Network {
 
 class SocketBase;
@@ -36,6 +41,26 @@ enum class Errno {
     NETUNREACH,
     TIMEDOUT,
     MSGSIZE,
+    INPROGRESS,
+    OTHER,
+};
+
+enum class GetAddrInfoError {
+    SUCCESS,
+    ADDRFAMILY,
+    AGAIN,
+    BADFLAGS,
+    FAIL,
+    FAMILY,
+    MEMORY,
+    NODATA,
+    NONAME,
+    SERVICE,
+    SOCKTYPE,
+    SYSTEM,
+    BADHINTS,
+    PROTOCOL,
+    OVERFLOW_,
     OTHER,
 };
 
@@ -49,6 +74,9 @@ enum class PollEvents : u16 {
     Err = 1 << 3,
     Hup = 1 << 4,
     Nval = 1 << 5,
+    RdNorm = 1 << 6,
+    RdBand = 1 << 7,
+    WrBand = 1 << 8,
 };
 
 DECLARE_ENUM_FLAG_OPERATORS(PollEvents);
@@ -82,4 +110,10 @@ constexpr IPv4Address TranslateIPv4(in_addr addr) {
 /// @return human ordered IPv4 address (e.g. 192.168.0.1) as an array
 std::optional<IPv4Address> GetHostIPv4Address();
 
+std::string IPv4AddressToString(IPv4Address ip_addr);
+u32 IPv4AddressToInteger(IPv4Address ip_addr);
+
+Common::Expected<std::vector<AddrInfo>, GetAddrInfoError> GetAddrInfo(
+    const std::string& host, const std::optional<std::string>& service);
+
 } // namespace Network
diff --git a/src/core/internal_network/socket_proxy.cpp b/src/core/internal_network/socket_proxy.cpp
index 7a77171c2..44e9e3093 100644
--- a/src/core/internal_network/socket_proxy.cpp
+++ b/src/core/internal_network/socket_proxy.cpp
@@ -98,7 +98,7 @@ Errno ProxySocket::Shutdown(ShutdownHow how) {
     return Errno::SUCCESS;
 }
 
-std::pair<s32, Errno> ProxySocket::Recv(int flags, std::vector<u8>& message) {
+std::pair<s32, Errno> ProxySocket::Recv(int flags, std::span<u8> message) {
     LOG_WARNING(Network, "(STUBBED) called");
     ASSERT(flags == 0);
     ASSERT(message.size() < static_cast<size_t>(std::numeric_limits<int>::max()));
@@ -106,7 +106,7 @@ std::pair<s32, Errno> ProxySocket::Recv(int flags, std::vector<u8>& message) {
     return {static_cast<s32>(0), Errno::SUCCESS};
 }
 
-std::pair<s32, Errno> ProxySocket::RecvFrom(int flags, std::vector<u8>& message, SockAddrIn* addr) {
+std::pair<s32, Errno> ProxySocket::RecvFrom(int flags, std::span<u8> message, SockAddrIn* addr) {
     ASSERT(flags == 0);
     ASSERT(message.size() < static_cast<size_t>(std::numeric_limits<int>::max()));
 
@@ -140,8 +140,8 @@ std::pair<s32, Errno> ProxySocket::RecvFrom(int flags, std::vector<u8>& message,
     }
 }
 
-std::pair<s32, Errno> ProxySocket::ReceivePacket(int flags, std::vector<u8>& message,
-                                                 SockAddrIn* addr, std::size_t max_length) {
+std::pair<s32, Errno> ProxySocket::ReceivePacket(int flags, std::span<u8> message, SockAddrIn* addr,
+                                                 std::size_t max_length) {
     ProxyPacket& packet = received_packets.front();
     if (addr) {
         addr->family = Domain::INET;
@@ -153,10 +153,7 @@ std::pair<s32, Errno> ProxySocket::ReceivePacket(int flags, std::vector<u8>& mes
     std::size_t read_bytes;
     if (packet.data.size() > max_length) {
         read_bytes = max_length;
-        message.clear();
-        std::copy(packet.data.begin(), packet.data.begin() + read_bytes,
-                  std::back_inserter(message));
-        message.resize(max_length);
+        memcpy(message.data(), packet.data.data(), max_length);
 
         if (protocol == Protocol::UDP) {
             if (!peek) {
@@ -171,9 +168,7 @@ std::pair<s32, Errno> ProxySocket::ReceivePacket(int flags, std::vector<u8>& mes
         }
     } else {
         read_bytes = packet.data.size();
-        message.clear();
-        std::copy(packet.data.begin(), packet.data.end(), std::back_inserter(message));
-        message.resize(max_length);
+        memcpy(message.data(), packet.data.data(), read_bytes);
         if (!peek) {
             received_packets.pop();
         }
@@ -293,6 +288,11 @@ Errno ProxySocket::SetNonBlock(bool enable) {
     return Errno::SUCCESS;
 }
 
+std::pair<Errno, Errno> ProxySocket::GetPendingError() {
+    LOG_DEBUG(Network, "(STUBBED) called");
+    return {Errno::SUCCESS, Errno::SUCCESS};
+}
+
 bool ProxySocket::IsOpened() const {
     return fd != INVALID_SOCKET;
 }
diff --git a/src/core/internal_network/socket_proxy.h b/src/core/internal_network/socket_proxy.h
index 6e991fa38..e12c413d1 100644
--- a/src/core/internal_network/socket_proxy.h
+++ b/src/core/internal_network/socket_proxy.h
@@ -39,11 +39,11 @@ public:
 
     Errno Shutdown(ShutdownHow how) override;
 
-    std::pair<s32, Errno> Recv(int flags, std::vector<u8>& message) override;
+    std::pair<s32, Errno> Recv(int flags, std::span<u8> message) override;
 
-    std::pair<s32, Errno> RecvFrom(int flags, std::vector<u8>& message, SockAddrIn* addr) override;
+    std::pair<s32, Errno> RecvFrom(int flags, std::span<u8> message, SockAddrIn* addr) override;
 
-    std::pair<s32, Errno> ReceivePacket(int flags, std::vector<u8>& message, SockAddrIn* addr,
+    std::pair<s32, Errno> ReceivePacket(int flags, std::span<u8> message, SockAddrIn* addr,
                                         std::size_t max_length);
 
     std::pair<s32, Errno> Send(std::span<const u8> message, int flags) override;
@@ -74,6 +74,8 @@ public:
     template <typename T>
     Errno SetSockOpt(SOCKET fd, int option, T value);
 
+    std::pair<Errno, Errno> GetPendingError() override;
+
     bool IsOpened() const override;
 
 private:
diff --git a/src/core/internal_network/sockets.h b/src/core/internal_network/sockets.h
index 11e479e50..46a53ef79 100644
--- a/src/core/internal_network/sockets.h
+++ b/src/core/internal_network/sockets.h
@@ -59,10 +59,9 @@ public:
 
     virtual Errno Shutdown(ShutdownHow how) = 0;
 
-    virtual std::pair<s32, Errno> Recv(int flags, std::vector<u8>& message) = 0;
+    virtual std::pair<s32, Errno> Recv(int flags, std::span<u8> message) = 0;
 
-    virtual std::pair<s32, Errno> RecvFrom(int flags, std::vector<u8>& message,
-                                           SockAddrIn* addr) = 0;
+    virtual std::pair<s32, Errno> RecvFrom(int flags, std::span<u8> message, SockAddrIn* addr) = 0;
 
     virtual std::pair<s32, Errno> Send(std::span<const u8> message, int flags) = 0;
 
@@ -87,6 +86,8 @@ public:
 
     virtual Errno SetNonBlock(bool enable) = 0;
 
+    virtual std::pair<Errno, Errno> GetPendingError() = 0;
+
     virtual bool IsOpened() const = 0;
 
     virtual void HandleProxyPacket(const ProxyPacket& packet) = 0;
@@ -126,9 +127,9 @@ public:
 
     Errno Shutdown(ShutdownHow how) override;
 
-    std::pair<s32, Errno> Recv(int flags, std::vector<u8>& message) override;
+    std::pair<s32, Errno> Recv(int flags, std::span<u8> message) override;
 
-    std::pair<s32, Errno> RecvFrom(int flags, std::vector<u8>& message, SockAddrIn* addr) override;
+    std::pair<s32, Errno> RecvFrom(int flags, std::span<u8> message, SockAddrIn* addr) override;
 
     std::pair<s32, Errno> Send(std::span<const u8> message, int flags) override;
 
@@ -156,6 +157,11 @@ public:
     template <typename T>
     Errno SetSockOpt(SOCKET fd, int option, T value);
 
+    std::pair<Errno, Errno> GetPendingError() override;
+
+    template <typename T>
+    std::pair<T, Errno> GetSockOpt(SOCKET fd, int option);
+
     bool IsOpened() const override;
 
     void HandleProxyPacket(const ProxyPacket& packet) override;