Merge pull request #12184 from noahpistilli/kd-mail-send

IOS/KD: Implement Send Mail

Source/Core/Common/HttpRequest.cpp

@@ -33,7 +33,8 @@ public:
   void FollowRedirects(long max);
   s32 GetLastResponseCode();
   Response Fetch(const std::string& url, Method method, const Headers& headers, const u8* payload,
-                 size_t size, AllowedReturnCodes codes = AllowedReturnCodes::Ok_Only);
+                 size_t size, AllowedReturnCodes codes = AllowedReturnCodes::Ok_Only,
+                 std::span<Multiform> multiform = {});
 
   static int CurlProgressCallback(Impl* impl, curl_off_t dltotal, curl_off_t dlnow,
                                   curl_off_t ultotal, curl_off_t ulnow);
@@ -174,6 +175,13 @@ void HttpRequest::Impl::UseIPv4()
   curl_easy_setopt(m_curl.get(), CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4);
 }
 
+HttpRequest::Response HttpRequest::PostMultiform(const std::string& url,
+                                                 std::span<Multiform> multiform,
+                                                 const Headers& headers, AllowedReturnCodes codes)
+{
+  return m_impl->Fetch(url, Impl::Method::POST, headers, nullptr, 0, codes, multiform);
+}
+
 void HttpRequest::Impl::FollowRedirects(long max)
 {
   curl_easy_setopt(m_curl.get(), CURLOPT_FOLLOWLOCATION, 1);
@@ -225,17 +233,33 @@ static size_t header_callback(char* buffer, size_t size, size_t nitems, void* us
 
 HttpRequest::Response HttpRequest::Impl::Fetch(const std::string& url, Method method,
                                                const Headers& headers, const u8* payload,
-                                               size_t size, AllowedReturnCodes codes)
+                                               size_t size, AllowedReturnCodes codes,
+                                               std::span<Multiform> multiform)
 {
   m_response_headers.clear();
   curl_easy_setopt(m_curl.get(), CURLOPT_POST, method == Method::POST);
   curl_easy_setopt(m_curl.get(), CURLOPT_URL, url.c_str());
-  if (method == Method::POST)
+  if (method == Method::POST && multiform.empty())
   {
     curl_easy_setopt(m_curl.get(), CURLOPT_POSTFIELDS, payload);
     curl_easy_setopt(m_curl.get(), CURLOPT_POSTFIELDSIZE, size);
   }
 
+  curl_mime* form = nullptr;
+  Common::ScopeGuard multiform_guard{[&form] { curl_mime_free(form); }};
+  if (!multiform.empty())
+  {
+    form = curl_mime_init(m_curl.get());
+    for (const auto& value : multiform)
+    {
+      curl_mimepart* part = curl_mime_addpart(form);
+      curl_mime_name(part, value.name.c_str());
+      curl_mime_data(part, value.data.c_str(), value.data.size());
+    }
+
+    curl_easy_setopt(m_curl.get(), CURLOPT_MIMEPOST, form);
+  }
+
   curl_slist* list = nullptr;
   Common::ScopeGuard list_guard{[&list] { curl_slist_free_all(list); }};
   for (const auto& [name, value] : headers)

Source/Core/Common/HttpRequest.h

@@ -8,6 +8,7 @@
 #include <map>
 #include <memory>
 #include <optional>
+#include <span>
 #include <string>
 #include <vector>
 
@@ -35,6 +36,12 @@ public:
   using Response = std::optional<std::vector<u8>>;
   using Headers = std::map<std::string, std::optional<std::string>>;
 
+  struct Multiform
+  {
+    std::string name;
+    std::string data;
+  };
+
   void SetCookies(const std::string& cookies);
   void UseIPv4();
   void FollowRedirects(long max = 1);
@@ -48,6 +55,10 @@ public:
   Response Post(const std::string& url, const std::string& payload, const Headers& headers = {},
                 AllowedReturnCodes codes = AllowedReturnCodes::Ok_Only);
 
+  Response PostMultiform(const std::string& url, std::span<Multiform> multiform,
+                         const Headers& headers = {},
+                         AllowedReturnCodes codes = AllowedReturnCodes::Ok_Only);
+
 private:
   class Impl;
   std::unique_ptr<Impl> m_impl;

Source/Core/Core/CMakeLists.txt

@@ -383,6 +383,8 @@ add_library(core
   IOS/Network/KD/VFF/VFFUtil.h
   IOS/Network/KD/WC24File.h
   IOS/Network/KD/Mail/MailCommon.h
+  IOS/Network/KD/Mail/WC24FriendList.cpp
+  IOS/Network/KD/Mail/WC24FriendList.h
   IOS/Network/KD/Mail/WC24Send.cpp
   IOS/Network/KD/Mail/WC24Send.h
   IOS/Network/MACUtils.cpp

Source/Core/Core/IOS/Network/KD/Mail/MailCommon.h

@@ -11,6 +11,11 @@ namespace IOS::HLE::NWC24::Mail
 {
 constexpr u32 MAIL_LIST_MAGIC = 0x57635466;  // WcTf
 
+inline u32 CalculateFileOffset(u32 index)
+{
+  return Common::swap32(128 + (index * 128));
+}
+
 #pragma pack(push, 1)
 struct MailListHeader final
 {

Source/Core/Core/IOS/Network/KD/Mail/WC24FriendList.cpp

@@ -0,0 +1,93 @@
+// Copyright 2023 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "Core/IOS/Network/KD/Mail/WC24FriendList.h"
+#include "Core/IOS/FS/FileSystem.h"
+#include "Core/IOS/Uids.h"
+
+namespace IOS::HLE::NWC24::Mail
+{
+WC24FriendList::WC24FriendList(std::shared_ptr<FS::FileSystem> fs) : m_fs{std::move(fs)}
+{
+  ReadFriendList();
+}
+
+void WC24FriendList::ReadFriendList()
+{
+  const auto file = m_fs->OpenFile(PID_KD, PID_KD, FRIEND_LIST_PATH, FS::Mode::Read);
+  if (!file || !file->Read(&m_data, 1))
+    return;
+
+  const bool success = CheckFriendList();
+  if (!success)
+    ERROR_LOG_FMT(IOS_WC24, "There is an error in the Receive List for WC24 mail");
+}
+
+void WC24FriendList::WriteFriendList() const
+{
+  constexpr FS::Modes public_modes{FS::Mode::ReadWrite, FS::Mode::ReadWrite, FS::Mode::ReadWrite};
+  m_fs->CreateFullPath(PID_KD, PID_KD, FRIEND_LIST_PATH, 0, public_modes);
+  const auto file = m_fs->CreateAndOpenFile(PID_KD, PID_KD, FRIEND_LIST_PATH, public_modes);
+
+  if (!file || !file->Write(&m_data, 1))
+    ERROR_LOG_FMT(IOS_WC24, "Failed to open or write WC24 Receive list file");
+}
+
+bool WC24FriendList::CheckFriendList() const
+{
+  // 'WcFl' magic
+  if (Common::swap32(m_data.header.magic) != FRIEND_LIST_MAGIC)
+  {
+    ERROR_LOG_FMT(IOS_WC24, "Receive List magic mismatch ({} != {})",
+                  Common::swap32(m_data.header.magic), FRIEND_LIST_MAGIC);
+    return false;
+  }
+
+  return true;
+}
+
+bool WC24FriendList::DoesFriendExist(u64 friend_id) const
+{
+  return std::any_of(m_data.friend_codes.cbegin(), m_data.friend_codes.cend(),
+                     [&friend_id](const u64 v) { return v == friend_id; });
+}
+
+std::vector<u64> WC24FriendList::GetUnconfirmedFriends() const
+{
+  std::vector<u64> friends{};
+  for (u32 i = 0; i < MAX_ENTRIES; i++)
+  {
+    if (static_cast<FriendStatus>(Common::swap32(m_data.entries[i].status)) ==
+            FriendStatus::Unconfirmed &&
+        static_cast<FriendType>(Common::swap32(m_data.entries[i].friend_type)) == FriendType::Wii)
+    {
+      friends.push_back(Common::swap64(m_data.friend_codes.at(i)));
+    }
+  }
+
+  return friends;
+}
+
+u64 WC24FriendList::ConvertEmailToFriendCode(std::string_view email)
+{
+  u32 upper = 0x80;
+  u32 lower{};
+
+  u32 idx{};
+  for (char chr : email)
+  {
+    if (idx == 7)
+    {
+      upper = upper | (email.size() & 0x1f);
+      break;
+    }
+
+    lower = (upper | chr) >> 0x18 | (lower | lower >> 0x1f) << 8;
+    upper = (upper | chr) * 0x100;
+    idx++;
+  }
+
+  return u64{lower} << 32 | upper;
+}
+
+}  // namespace IOS::HLE::NWC24::Mail

Source/Core/Core/IOS/Network/KD/Mail/WC24FriendList.h

@@ -0,0 +1,98 @@
+// Copyright 2023 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <array>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "Common/CommonPaths.h"
+#include "Common/CommonTypes.h"
+#include "Common/Logging/Log.h"
+#include "Common/Swap.h"
+#include "Core/IOS/Network/KD/NWC24Config.h"
+
+namespace IOS::HLE
+{
+namespace FS
+{
+class FileSystem;
+}
+namespace NWC24::Mail
+{
+constexpr const char FRIEND_LIST_PATH[] = "/" WII_WC24CONF_DIR "/nwc24fl.bin";
+class WC24FriendList final
+{
+public:
+  explicit WC24FriendList(std::shared_ptr<FS::FileSystem> fs);
+  static u64 ConvertEmailToFriendCode(std::string_view email);
+
+  void ReadFriendList();
+  bool CheckFriendList() const;
+  void WriteFriendList() const;
+
+  bool DoesFriendExist(u64 friend_id) const;
+  std::vector<u64> GetUnconfirmedFriends() const;
+
+private:
+  static constexpr u32 FRIEND_LIST_MAGIC = 0x5763466C;  // WcFl
+  static constexpr u32 MAX_ENTRIES = 100;
+
+#pragma pack(push, 1)
+  struct FriendListHeader final
+  {
+    u32 magic;  // 'WcFl' 0x5763466C
+    u32 version;
+    u32 max_friend_entries;
+    u32 number_of_friends;
+    char padding[48];
+  };
+  static_assert(sizeof(FriendListHeader) == 64);
+  static_assert(std::is_trivially_copyable_v<FriendListHeader>);
+
+  enum class FriendType : u32
+  {
+    None,
+    Wii,
+    Email
+  };
+
+  enum class FriendStatus : u32
+  {
+    None,
+    Unconfirmed,
+    Confirmed,
+    Declined
+  };
+
+  struct FriendListEntry final
+  {
+    u32 friend_type;
+    u32 status;
+    char nickname[24];
+    u32 mii_id;
+    u32 system_id;
+    char reserved[24];
+    char email_or_code[96];
+    char padding[160];
+  };
+  static_assert(sizeof(FriendListEntry) == 320);
+  static_assert(std::is_trivially_copyable_v<FriendListEntry>);
+
+  struct FriendList final
+  {
+    FriendListHeader header;
+    std::array<u64, MAX_ENTRIES> friend_codes;
+    std::array<FriendListEntry, MAX_ENTRIES> entries;
+  };
+  static_assert(sizeof(FriendList) == 32864);
+  static_assert(std::is_trivially_copyable_v<FriendList>);
+#pragma pack(pop)
+
+  FriendList m_data;
+  std::shared_ptr<FS::FileSystem> m_fs;
+};
+}  // namespace NWC24::Mail
+}  // namespace IOS::HLE

Source/Core/Core/IOS/Network/KD/Mail/WC24Send.cpp

@@ -3,8 +3,10 @@
 
 #include "Core/IOS/Network/KD/Mail/WC24Send.h"
 #include "Core/IOS/FS/FileSystem.h"
+#include "Core/IOS/Network/KD/VFF/VFFUtil.h"
 #include "Core/IOS/Uids.h"
 
+#include <fmt/chrono.h>
 #include "Common/Assert.h"
 
 namespace IOS::HLE::NWC24::Mail
@@ -44,7 +46,28 @@ bool WC24SendList::ReadSendList()
     return false;
   }
 
-  return CheckSendList();
+  // Make sure that next_entry_offset is not out of bounds.
+  if (m_data.header.next_entry_offset % 128 != 0 ||
+      m_data.header.next_entry_offset >
+          sizeof(MailListEntry) * (MAX_ENTRIES - 1) + sizeof(MailListEntry))
+  {
+    const std::optional<u32> next_entry_index = GetNextFreeEntryIndex();
+    if (!next_entry_index)
+    {
+      // If there are no free entries, we will have to overwrite an entry.
+      m_data.header.next_entry_offset = Common::swap32(128);
+    }
+    else
+    {
+      m_data.header.next_entry_offset = CalculateFileOffset(next_entry_index.value());
+    }
+  }
+
+  const s32 file_error = CheckSendList();
+  if (!file_error)
+    ERROR_LOG_FMT(IOS_WC24, "There is an error in the Send List for WC24 mail");
+
+  return true;
 }
 
 bool WC24SendList::IsDisabled() const
@@ -82,6 +105,147 @@ bool WC24SendList::CheckSendList() const
   return true;
 }
 
+u32 WC24SendList::GetNumberOfMail() const
+{
+  ASSERT(!IsDisabled());
+  return Common::swap32(m_data.header.number_of_mail);
+}
+
+u32 WC24SendList::GetEntryId(u32 entry_index) const
+{
+  ASSERT(!IsDisabled());
+  return Common::swap32(m_data.entries[entry_index].id);
+}
+
+u32 WC24SendList::GetMailSize(u32 index) const
+{
+  ASSERT(!IsDisabled());
+  return Common::swap32(m_data.entries[index].msg_size);
+}
+
+ErrorCode WC24SendList::DeleteMessage(u32 index)
+{
+  ASSERT(!IsDisabled());
+  ErrorCode error = NWC24::DeleteFileFromVFF(NWC24::Mail::SEND_BOX_PATH, GetMailPath(index), m_fs);
+  if (error != WC24_OK)
+    return error;
+
+  // Fix up the header then clear the entry.
+  m_data.header.number_of_mail = Common::swap32(Common::swap32(m_data.header.number_of_mail) - 1);
+  m_data.header.next_entry_id = Common::swap32(GetEntryId(index));
+  m_data.header.next_entry_offset = CalculateFileOffset(index);
+  m_data.header.total_size_of_messages =
+      Common::swap32(m_data.header.total_size_of_messages) - GetMailSize(index);
+
+  std::memset(&m_data.entries[index], 0, sizeof(MailListEntry));
+  return WC24_OK;
+}
+
+std::string WC24SendList::GetMailPath(u32 index) const
+{
+  return fmt::format("mb/s{:07d}.msg", GetEntryId(index));
+}
+
+u32 WC24SendList::GetNextEntryId() const
+{
+  ASSERT(!IsDisabled());
+  return Common::swap32(m_data.header.next_entry_id);
+}
+
+u32 WC24SendList::GetNextEntryIndex() const
+{
+  ASSERT(!IsDisabled());
+  return (Common::swap32(m_data.header.next_entry_offset) - 128) / 128;
+}
+
+std::vector<u32> WC24SendList::GetMailToSend() const
+{
+  ASSERT(!IsDisabled());
+  // The list is not guaranteed to have all entries consecutively.
+  // As such we must find the populated entries for the specified number of mails.
+  const u32 mail_count = std::min(GetNumberOfMail(), 16U);
+  u32 found{};
+
+  std::vector<u32> mails{};
+  for (u32 index = 0; index < MAX_ENTRIES; index++)
+  {
+    if (found == mail_count)
+      break;
+
+    if (GetEntryId(index) != 0)
+    {
+      mails.emplace_back(index);
+      found++;
+    }
+  }
+
+  return mails;
+}
+
+std::optional<u32> WC24SendList::GetNextFreeEntryIndex() const
+{
+  for (u32 index = 0; index < MAX_ENTRIES; index++)
+  {
+    if (GetEntryId(index) == 0)
+      return index;
+  }
+
+  return std::nullopt;
+}
+
+ErrorCode WC24SendList::AddRegistrationMessages(const WC24FriendList& friend_list, u64 sender)
+{
+  ASSERT(!IsDisabled());
+  // It is possible that the user composed a message before SendMail was called.
+  ReadSendList();
+
+  const std::vector<u64> unconfirmed_friends = friend_list.GetUnconfirmedFriends();
+  for (const u64 code : unconfirmed_friends)
+  {
+    const u32 entry_index = GetNextEntryIndex();
+    const u32 msg_id = GetNextEntryId();
+    m_data.entries[entry_index].id = Common::swap32(msg_id);
+
+    std::time_t t = std::time(nullptr);
+
+    const std::string formatted_message =
+        fmt::format(MAIL_REGISTRATION_STRING, sender, code, fmt::gmtime(t));
+    std::vector<u8> message{formatted_message.begin(), formatted_message.end()};
+    NWC24::ErrorCode reply =
+        NWC24::WriteToVFF(NWC24::Mail::SEND_BOX_PATH, GetMailPath(entry_index), m_fs, message);
+
+    if (reply != WC24_OK)
+    {
+      ERROR_LOG_FMT(IOS_WC24, "Error writing registration message to VFF");
+      return reply;
+    }
+
+    NOTICE_LOG_FMT(IOS_WC24, "Issued registration message for Wii Friend: {}", code);
+
+    // Update the header and some fields in the body
+    m_data.entries[entry_index].msg_size = Common::swap32(static_cast<u32>(message.size()));
+    m_data.header.number_of_mail = Common::swap32(GetNumberOfMail() + 1);
+    m_data.header.next_entry_id = Common::swap32(msg_id + 1);
+    m_data.header.total_size_of_messages =
+        Common::swap32(m_data.header.total_size_of_messages) + static_cast<u32>(message.size());
+
+    const std::optional<u32> next_entry_index = GetNextFreeEntryIndex();
+    if (!next_entry_index)
+    {
+      // If there are no free entries, we overwrite the first entry.
+      m_data.header.next_entry_offset = Common::swap32(128);
+    }
+    else
+    {
+      m_data.header.next_entry_offset = CalculateFileOffset(next_entry_index.value());
+    }
+  }
+
+  // Only flush on success.
+  WriteSendList();
+  return WC24_OK;
+}
+
 std::string_view WC24SendList::GetMailFlag() const
 {
   ASSERT(!IsDisabled());

Source/Core/Core/IOS/Network/KD/Mail/WC24Send.h

@@ -3,13 +3,16 @@
 
 #pragma once
 
+#include <optional>
 #include <string_view>
+#include <vector>
 
 #include "Common/CommonPaths.h"
 #include "Common/CommonTypes.h"
 #include "Common/Logging/Log.h"
 #include "Common/Swap.h"
 #include "Core/IOS/Network/KD/Mail/MailCommon.h"
+#include "Core/IOS/Network/KD/Mail/WC24FriendList.h"
 #include "Core/IOS/Network/KD/NWC24Config.h"
 
 namespace IOS::HLE
@@ -34,11 +37,56 @@ public:
   bool IsDisabled() const;
 
   std::string_view GetMailFlag() const;
+  u32 GetNumberOfMail() const;
+  std::vector<u32> GetMailToSend() const;
+  u32 GetEntryId(u32 entry_index) const;
+  u32 GetMailSize(u32 index) const;
+  ErrorCode DeleteMessage(u32 index);
+  std::string GetMailPath(u32 index) const;
+  u32 GetNextEntryId() const;
+  u32 GetNextEntryIndex() const;
+  std::optional<u32> GetNextFreeEntryIndex() const;
+
+  ErrorCode AddRegistrationMessages(const WC24FriendList& friend_list, u64 sender);
 
 private:
   static constexpr u32 MAX_ENTRIES = 127;
   static constexpr u32 SEND_LIST_SIZE = 16384;
 
+  // Format for the message Wii Mail sends when trying to register a Wii Friend.
+  // Most fields can be static such as the X-Wii-AppId which is the Wii Menu,
+  // X-Wii-Cmd which is the registration command, and the attached file which is
+  // just 128 bytes of base64 encoded 0 bytes. That file is supposed to be friend profile data which
+  // is written to nwc24fl.bin, although it has been observed to always be 0.
+  static constexpr char MAIL_REGISTRATION_STRING[] =
+      "MAIL FROM: {0:016d}@wii.com\r\n"
+      "RCPT TO: {1:016d}wii.com\r\n"
+      "DATA\r\n"
+      "Date: {2:%a, %d %b %Y %X} GMT\r\n"
+      "From: {0:016d}@wii.com\r\n"
+      "To: {1:016d}@wii.com\r\n"
+      "Message-Id: <00002000B0DF6BB47FE0303E0DB0D@wii.com>\r\n"
+      "Subject: WC24 Cmd Message\r\n"
+      "X-Wii-AppId: 0-00000001-0001\r\n"
+      "X-Wii-Cmd: 80010001\r\n"
+      "MIME-Version: 1.0\r\n"
+      "Content-Type: multipart/mixed;\r\n "
+      "boundary=\"Boundary-NWC24-041B6CE500012\"\r\n"
+      "--Boundary-NWC24-041B6CE500012\r\n"
+      "Content-Type: text/plain; charset=us-ascii\r\n"
+      "Content-Transfer-Encoding: 7bit\r\n"
+      "WC24 Cmd Message\r\n"
+      "--Boundary-NWC24-041B6CE500012\r\n"
+      "Content-Type: application/octet-stream;\r\n "
+      "name=a0000018.dat\r\n"
+      "Content-Transfer-Encoding: base64\r\n"
+      "Content-Disposition: attachment;\r\n "
+      "filename=a0000018.dat\r\n\r\n "
+      "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+      "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA="
+      "\r\n\r\n"
+      "--Boundary-NWC24-041B6CE500012--";
+
 #pragma pack(push, 1)
   struct SendList final
   {

Source/Core/Core/IOS/Network/KD/NWC24Config.cpp

@@ -246,4 +246,16 @@ void NWC24Config::SetPassword(std::string_view password)
   std::strncpy(m_data.paswd, password.data(), std::size(m_data.paswd));
   m_data.paswd[MAX_PASSWORD_LENGTH - 1] = '\0';
 }
+
+std::string NWC24Config::GetSendURL() const
+{
+  const size_t size = strnlen(m_data.http_urls[4], MAX_URL_LENGTH);
+  return {m_data.http_urls[4], size};
+}
+
+std::string_view NWC24Config::GetPassword() const
+{
+  const size_t size = strnlen(m_data.paswd, MAX_PASSWORD_LENGTH);
+  return {m_data.paswd, size};
+}
 }  // namespace IOS::HLE::NWC24

Source/Core/Core/IOS/Network/KD/NWC24Config.h

@@ -34,6 +34,8 @@ enum ErrorCode : s32
   WC24_ERR_ID_REGISTERED = -36,
   WC24_ERR_DISABLED = -39,
   WC24_ERR_ID_NOT_REGISTERED = -44,
+  WC24_MSG_DAMAGED = -71,
+  WC24_MSG_TOO_BIG = -72
 };
 
 enum class NWC24CreationStage : u32
@@ -72,6 +74,8 @@ public:
 
   std::string_view GetMlchkid() const;
   std::string GetCheckURL() const;
+  std::string GetSendURL() const;
+  std::string_view GetPassword() const;
 
   NWC24CreationStage CreationStage() const;
   void SetCreationStage(NWC24CreationStage creation_stage);

Source/Core/Core/IOS/Network/KD/NetKDRequest.cpp

@@ -155,7 +155,7 @@ s32 NWC24MakeUserID(u64* nwc24_id, u32 hollywood_id, u16 id_ctr, HardwareModel h
 
 NetKDRequestDevice::NetKDRequestDevice(EmulationKernel& ios, const std::string& device_name)
     : EmulationDevice(ios, device_name), m_config{ios.GetFS()}, m_dl_list{ios.GetFS()},
-      m_send_list{ios.GetFS()}
+      m_send_list{ios.GetFS()}, m_friend_list{ios.GetFS()}
 {
   // Enable all NWC24 permissions
   m_scheduler_buffer[1] = Common::swap32(-1);
@@ -275,6 +275,12 @@ void NetKDRequestDevice::SchedulerWorker(const SchedulerEvent event)
     {
       LogError(ErrorType::CheckMail, code);
     }
+
+    code = KDSendMail();
+    if (code != NWC24::WC24_OK)
+    {
+      LogError(ErrorType::SendMail, code);
+    }
   }
 }
 
@@ -315,6 +321,15 @@ void NetKDRequestDevice::LogError(ErrorType error_type, s32 error_code)
   case ErrorType::CheckMail:
     new_code = -(102200 - error_code);
     break;
+  case ErrorType::SendMail:
+    new_code = -(105000 - error_code);
+    break;
+  case ErrorType::ReceiveMail:
+    new_code = -(100300 - error_code);
+    break;
+  case ErrorType::CGI:
+    new_code = -(error_code + 110000);
+    break;
   }
 
   std::lock_guard lg(m_scheduler_buffer_lock);
@@ -498,6 +513,133 @@ NWC24::ErrorCode NetKDRequestDevice::DetermineSubtask(u16 entry_index,
   return NWC24::WC24_ERR_INVALID_VALUE;
 }
 
+NWC24::ErrorCode NetKDRequestDevice::KDSendMail()
+{
+  bool success = false;
+  Common::ScopeGuard exit_guard([&] {
+    std::lock_guard lg(m_scheduler_buffer_lock);
+    if (success)
+    {
+      // m_scheduler_buffer[11] contains the amount of times we have sent for mail this IOS
+      // session.
+      m_scheduler_buffer[14] = Common::swap32(Common::swap32(m_scheduler_buffer[14]) + 1);
+    }
+    m_scheduler_buffer[4] = static_cast<u32>(CurrentFunction::None);
+
+    m_send_list.WriteSendList();
+  });
+
+  {
+    std::lock_guard lg(m_scheduler_buffer_lock);
+    m_scheduler_buffer[4] = Common::swap32(static_cast<u32>(CurrentFunction::Send));
+  }
+
+  m_send_list.ReadSendList();
+  const std::string auth =
+      fmt::format("mlid=w{}\r\npasswd={}", m_config.Id(), m_config.GetPassword());
+  std::vector<Common::HttpRequest::Multiform> multiform = {{"mlid", auth}};
+
+  std::vector<u32> mails = m_send_list.GetMailToSend();
+  for (const u32 file_index : mails)
+  {
+    const u32 entry_id = m_send_list.GetEntryId(file_index);
+    const u32 mail_size = m_send_list.GetMailSize(file_index);
+    if (mail_size > MAX_MAIL_SIZE)
+    {
+      WARN_LOG_FMT(IOS_WC24,
+                   "NET_KD_REQ: IOCTL_NWC24_SEND_MAIL_NOW: Mail at index {} was too large to send.",
+                   entry_id);
+      LogError(ErrorType::SendMail, NWC24::WC24_MSG_TOO_BIG);
+
+      NWC24::ErrorCode res = m_send_list.DeleteMessage(file_index);
+      if (res != NWC24::WC24_OK)
+      {
+        LogError(ErrorType::SendMail, res);
+      }
+      mails.erase(std::remove(mails.begin(), mails.end(), file_index), mails.end());
+      continue;
+    }
+
+    std::vector<u8> mail_data(mail_size);
+    NWC24::ErrorCode res = NWC24::ReadFromVFF(
+        NWC24::Mail::SEND_BOX_PATH, m_send_list.GetMailPath(file_index), m_ios.GetFS(), mail_data);
+    if (res != NWC24::WC24_OK)
+    {
+      ERROR_LOG_FMT(IOS_WC24, "Reading mail at index {} failed with error code {}.", entry_id,
+                    static_cast<s32>(res));
+      LogError(ErrorType::SendMail, NWC24::WC24_MSG_DAMAGED);
+      res = m_send_list.DeleteMessage(file_index);
+      if (res != NWC24::WC24_OK)
+      {
+        LogError(ErrorType::SendMail, res);
+      }
+
+      mails.erase(std::remove(mails.begin(), mails.end(), file_index), mails.end());
+      continue;
+    }
+
+    const std::string mail_str = {mail_data.begin(), mail_data.end()};
+
+    multiform.push_back({fmt::format("m{}", entry_id), mail_str});
+  }
+
+  const Common::HttpRequest::Response response =
+      m_http.PostMultiform(m_config.GetSendURL(), multiform);
+
+  if (!response)
+  {
+    ERROR_LOG_FMT(IOS_WC24, "NET_KD_REQ: IOCTL_NWC24_SEND_MAIL_NOW: Failed to request data at {}.",
+                  m_config.GetSendURL());
+    return NWC24::WC24_ERR_SERVER;
+  }
+
+  // Now check if any mail failed to save to the server.
+  const std::string response_str = {response->begin(), response->end()};
+  const std::string code = GetValueFromCGIResponse(response_str, "cd");
+  if (code != "100")
+  {
+    ERROR_LOG_FMT(
+        IOS_WC24,
+        "NET_KD_REQ: IOCTL_NWC24_CHECK_MAIL_NOW: Mail server returned non-success code: {}", code);
+    return NWC24::WC24_ERR_SERVER;
+  }
+
+  // Reverse in order to delete from bottom to top of the send list.
+  // We do this to ensure that new entries can be written as close to the beginning of the file as
+  // possible.
+  for (auto it = mails.rbegin(); it != mails.rend(); ++it)
+  {
+    const u32 entry_id = m_send_list.GetEntryId(*it);
+    Common::ScopeGuard delete_guard([&] {
+      NWC24::ErrorCode res = m_send_list.DeleteMessage(*it);
+      if (res != NWC24::WC24_OK)
+      {
+        LogError(ErrorType::SendMail, res);
+      }
+    });
+
+    const std::string value = GetValueFromCGIResponse(response_str, fmt::format("cd{}", entry_id));
+
+    s32 cgi_code{};
+    const bool did_parse = TryParse(value, &cgi_code);
+    if (!did_parse)
+    {
+      ERROR_LOG_FMT(IOS_WC24, "Mail server returned invalid CGI response code.");
+      LogError(ErrorType::CGI, NWC24::WC24_ERR_SERVER);
+      break;
+    }
+
+    if (cgi_code != 100)
+    {
+      ERROR_LOG_FMT(IOS_WC24, "Mail server failed to save mail at index {}", entry_id);
+      LogError(ErrorType::CGI, cgi_code);
+    }
+  }
+
+  success = true;
+  return NWC24::WC24_OK;
+}
+
 NWC24::ErrorCode NetKDRequestDevice::KDDownload(const u16 entry_index,
                                                 const std::optional<u8> subtask_id)
 {
@@ -622,8 +764,8 @@ NWC24::ErrorCode NetKDRequestDevice::KDDownload(const u16 entry_index,
     }
   }
 
-  NWC24::ErrorCode reply = IOS::HLE::NWC24::OpenVFF(m_dl_list.GetVFFPath(entry_index), content_name,
+  NWC24::ErrorCode reply = IOS::HLE::NWC24::WriteToVFF(m_dl_list.GetVFFPath(entry_index),
-                                                    m_ios.GetFS(), file_data);
+                                                       content_name, m_ios.GetFS(), file_data);
 
   if (reply != NWC24::WC24_OK)
   {
@@ -657,6 +799,13 @@ IPCReply NetKDRequestDevice::HandleNWC24CheckMailNow(const IOCtlRequest& request
   return IPCReply(IPC_SUCCESS);
 }
 
+IPCReply NetKDRequestDevice::HandleNWC24SendMailNow(const IOCtlRequest& request)
+{
+  const NWC24::ErrorCode reply = KDSendMail();
+  WriteReturnValue(reply, request.buffer_out);
+  return IPCReply(IPC_SUCCESS);
+}
+
 IPCReply NetKDRequestDevice::HandleNWC24DownloadNowEx(const IOCtlRequest& request)
 {
   if (m_dl_list.IsDisabled() || !m_dl_list.ReadDlList())
@@ -981,6 +1130,9 @@ std::optional<IPCReply> NetKDRequestDevice::IOCtl(const IOCtlRequest& request)
   case IOCTL_NWC24_DOWNLOAD_NOW_EX:
     return LaunchAsyncTask(&NetKDRequestDevice::HandleNWC24DownloadNowEx, request);
 
+  case IOCTL_NWC24_SEND_MAIL_NOW:
+    return LaunchAsyncTask(&NetKDRequestDevice::HandleNWC24SendMailNow, request);
+
   case IOCTL_NWC24_REQUEST_SHUTDOWN:
   {
     if (request.buffer_in == 0 || request.buffer_in % 4 != 0 || request.buffer_in_size < 8 ||

Source/Core/Core/IOS/Network/KD/NetKDRequest.h

@@ -13,6 +13,7 @@
 #include "Common/HttpRequest.h"
 #include "Common/WorkQueueThread.h"
 #include "Core/IOS/Device.h"
+#include "Core/IOS/Network/KD/Mail/WC24FriendList.h"
 #include "Core/IOS/Network/KD/Mail/WC24Send.h"
 #include "Core/IOS/Network/KD/NWC24Config.h"
 #include "Core/IOS/Network/KD/NWC24DL.h"
@@ -72,6 +73,9 @@ private:
     Client,
     Server,
     CheckMail,
+    SendMail,
+    ReceiveMail,
+    CGI,
   };
 
   enum class SchedulerEvent
@@ -80,14 +84,18 @@ private:
     Download,
   };
 
+  IPCReply HandleNWC24SendMailNow(const IOCtlRequest& request);
   NWC24::ErrorCode KDCheckMail(u32* mail_flag, u32* interval);
   IPCReply HandleRequestRegisterUserId(const IOCtlRequest& request);
+  NWC24::ErrorCode KDSendMail();
+
   void LogError(ErrorType error_type, s32 error_code);
   void SchedulerTimer();
   void SchedulerWorker(SchedulerEvent event);
   NWC24::ErrorCode DetermineDownloadTask(u16* entry_index, std::optional<u8>* subtask_id) const;
   NWC24::ErrorCode DetermineSubtask(u16 entry_index, std::optional<u8>* subtask_id) const;
 
+  static constexpr u32 MAX_MAIL_SIZE = 208952;
   static std::string GetValueFromCGIResponse(const std::string& response, const std::string& key);
   static constexpr std::array<u8, 20> MAIL_CHECK_KEY = {0xce, 0x4c, 0xf2, 0x9a, 0x3d, 0x6b, 0xe1,
                                                         0xc2, 0x61, 0x91, 0x72, 0xb5, 0xcb, 0x29,
@@ -98,6 +106,7 @@ private:
   NWC24::NWC24Config m_config;
   NWC24::NWC24Dl m_dl_list;
   NWC24::Mail::WC24SendList m_send_list;
+  NWC24::Mail::WC24FriendList m_friend_list;
   Common::WorkQueueThread<AsyncTask> m_work_queue;
   Common::WorkQueueThread<std::function<void()>> m_scheduler_work_queue;
   std::mutex m_async_reply_lock;

Source/Core/Core/IOS/Network/KD/VFF/VFFUtil.cpp

@@ -237,6 +237,48 @@ static ErrorCode WriteFile(const std::string& filename, const std::vector<u8>& t
   return WC24_OK;
 }
 
+static ErrorCode ReadFile(const std::string& filename, std::vector<u8>& out)
+{
+  FIL src{};
+  const auto open_error_code = f_open(&src, filename.c_str(), FA_READ);
+  if (open_error_code != FR_OK)
+  {
+    ERROR_LOG_FMT(IOS_WC24, "Failed to open file {} in VFF", filename);
+    return WC24_ERR_FILE_OPEN;
+  }
+
+  Common::ScopeGuard vff_close_guard{[&] { f_close(&src); }};
+
+  u32 size = static_cast<u32>(out.size());
+  u32 read_size{};
+  const auto read_error_code = f_read(&src, out.data(), size, &read_size);
+  if (read_error_code != FR_OK)
+  {
+    ERROR_LOG_FMT(IOS_WC24, "Failed to read file {} in VFF: {}", filename,
+                  static_cast<u32>(read_error_code));
+    return WC24_ERR_FILE_READ;
+  }
+
+  if (read_size != size)
+  {
+    ERROR_LOG_FMT(IOS_WC24, "Failed to read bytes of file {} to VFF ({} != {})", filename,
+                  read_size, size);
+    return WC24_ERR_FILE_READ;
+  }
+
+  // As prior operations did not fail, dismiss the guard and handle a potential error with f_close.
+  vff_close_guard.Dismiss();
+
+  const auto close_error_code = f_close(&src);
+  if (close_error_code != FR_OK)
+  {
+    ERROR_LOG_FMT(IOS_WC24, "Failed to close file {} in VFF", filename);
+    return WC24_ERR_FILE_CLOSE;
+  }
+
+  return WC24_OK;
+}
+
 namespace
 {
 class VffFatFsCallbacks : public Common::FatFsCallbacks
@@ -258,7 +300,7 @@ public:
 };
 }  // namespace
 
-ErrorCode OpenVFF(const std::string& path, const std::string& filename,
+ErrorCode WriteToVFF(const std::string& path, const std::string& filename,
                      const std::shared_ptr<FS::FileSystem>& fs, const std::vector<u8>& data)
 {
   VffFatFsCallbacks callbacks;
@@ -286,6 +328,8 @@ ErrorCode OpenVFF(const std::string& path, const std::string& filename,
       return;
     }
 
+    Common::ScopeGuard unmount_guard{[] { f_unmount(""); }};
+
     const FRESULT vff_mount_error_code = vff_mount(callbacks.m_vff, &fatfs);
     if (vff_mount_error_code != FR_OK)
     {
@@ -295,8 +339,6 @@ ErrorCode OpenVFF(const std::string& path, const std::string& filename,
       return;
     }
 
-    Common::ScopeGuard unmount_guard{[] { f_unmount(""); }};
-
     const auto write_error_code = WriteFile(filename, data);
     if (write_error_code != WC24_OK)
     {
@@ -312,4 +354,108 @@ ErrorCode OpenVFF(const std::string& path, const std::string& filename,
 
   return return_value;
 }
+
+ErrorCode ReadFromVFF(const std::string& path, const std::string& filename,
+                      const std::shared_ptr<FS::FileSystem>& fs, std::vector<u8>& out)
+{
+  VffFatFsCallbacks callbacks;
+  ErrorCode return_value;
+  Common::RunInFatFsContext(callbacks, [&]() {
+    auto temp = fs->OpenFile(PID_KD, PID_KD, path, FS::Mode::ReadWrite);
+    if (!temp)
+    {
+      ERROR_LOG_FMT(IOS_WC24, "Failed to open VFF at: {}", path);
+      return_value = WC24_ERR_NOT_FOUND;
+      return;
+    }
+
+    callbacks.m_vff = &*temp;
+
+    FATFS fatfs{};
+    const FRESULT fatfs_mount_error_code = f_mount(&fatfs, "", 0);
+    if (fatfs_mount_error_code != FR_OK)
+    {
+      // The VFF is most likely broken.
+      ERROR_LOG_FMT(IOS_WC24, "Failed to mount VFF at: {}", path);
+      return_value = WC24_ERR_BROKEN;
+      return;
+    }
+
+    Common::ScopeGuard unmount_guard{[] { f_unmount(""); }};
+
+    const FRESULT vff_mount_error_code = vff_mount(callbacks.m_vff, &fatfs);
+    if (vff_mount_error_code != FR_OK)
+    {
+      // The VFF is most likely broken.
+      ERROR_LOG_FMT(IOS_WC24, "Failed to mount VFF at: {}", path);
+      return_value = WC24_ERR_BROKEN;
+      return;
+    }
+
+    const ErrorCode read_error_code = ReadFile(filename, out);
+    if (read_error_code != WC24_OK)
+    {
+      return_value = read_error_code;
+      return;
+    }
+
+    return_value = WC24_OK;
+    return;
+  });
+
+  return return_value;
+}
+
+ErrorCode DeleteFileFromVFF(const std::string& path, const std::string& filename,
+                            const std::shared_ptr<FS::FileSystem>& fs)
+{
+  VffFatFsCallbacks callbacks;
+  ErrorCode return_value;
+  Common::RunInFatFsContext(callbacks, [&]() {
+    auto temp = fs->OpenFile(PID_KD, PID_KD, path, FS::Mode::ReadWrite);
+    if (!temp)
+    {
+      ERROR_LOG_FMT(IOS_WC24, "Failed to open VFF at: {}", path);
+      return_value = WC24_ERR_NOT_FOUND;
+      return;
+    }
+
+    callbacks.m_vff = &*temp;
+
+    FATFS fatfs{};
+    const FRESULT fatfs_mount_error_code = f_mount(&fatfs, "", 0);
+    if (fatfs_mount_error_code != FR_OK)
+    {
+      // The VFF is most likely broken.
+      ERROR_LOG_FMT(IOS_WC24, "Failed to mount VFF at: {}", path);
+      return_value = WC24_ERR_BROKEN;
+      return;
+    }
+
+    Common::ScopeGuard unmount_guard{[] { f_unmount(""); }};
+
+    const FRESULT vff_mount_error_code = vff_mount(callbacks.m_vff, &fatfs);
+    if (vff_mount_error_code != FR_OK)
+    {
+      // The VFF is most likely broken.
+      ERROR_LOG_FMT(IOS_WC24, "Failed to mount VFF at: {}", path);
+      return_value = WC24_ERR_BROKEN;
+      return;
+    }
+
+    const FRESULT unlink_code = f_unlink(filename.c_str());
+    if (unlink_code != FR_OK)
+    {
+      ERROR_LOG_FMT(IOS_WC24, "Failed to delete file {} in VFF at: {} Code: {}", filename, path,
+                    static_cast<u32>(unlink_code));
+      return_value = WC24_ERR_BROKEN;
+      return;
+    }
+
+    return_value = WC24_OK;
+    return;
+  });
+
+  return return_value;
+}
 }  // namespace IOS::HLE::NWC24

Source/Core/Core/IOS/Network/KD/VFF/VFFUtil.h

@@ -22,8 +22,12 @@ namespace NWC24
 constexpr u16 SECTOR_SIZE = 512;
 constexpr u16 VF_LITTLE_ENDIAN = 0xFFFE;
 constexpr u16 VF_BIG_ENDIAN = 0xFEFF;
-ErrorCode OpenVFF(const std::string& path, const std::string& filename,
+ErrorCode WriteToVFF(const std::string& path, const std::string& filename,
                      const std::shared_ptr<FS::FileSystem>& fs, const std::vector<u8>& data);
+ErrorCode ReadFromVFF(const std::string& path, const std::string& filename,
+                      const std::shared_ptr<FS::FileSystem>& fs, std::vector<u8>& out);
+ErrorCode DeleteFileFromVFF(const std::string& path, const std::string& filename,
+                            const std::shared_ptr<FS::FileSystem>& fs);
 
 #pragma pack(push, 1)
 struct VFFHeader final

Source/Core/DolphinLib.props

@@ -366,6 +366,7 @@
     <ClInclude Include="Core\IOS\Network\KD\VFF\VFFUtil.h" />
     <ClInclude Include="Core\IOS\Network\KD\WC24File.h" />
     <ClInclude Include="Core\IOS\Network\KD\Mail\MailCommon.h" />
+    <ClInclude Include="Core\IOS\Network\KD\Mail\WC24FriendList.h" />
     <ClInclude Include="Core\IOS\Network\KD\Mail\WC24Send.h" />
     <ClInclude Include="Core\IOS\Network\MACUtils.h" />
     <ClInclude Include="Core\IOS\Network\NCD\Manage.h" />
@@ -1017,6 +1018,7 @@
     <ClCompile Include="Core\IOS\Network\KD\NWC24Config.cpp" />
     <ClCompile Include="Core\IOS\Network\KD\NWC24DL.cpp" />
     <ClCompile Include="Core\IOS\Network\KD\VFF\VFFUtil.cpp" />
+    <ClCompile Include="Core\IOS\Network\KD\Mail\WC24FriendList.cpp" />
     <ClCompile Include="Core\IOS\Network\KD\Mail\WC24Send.cpp" />
     <ClCompile Include="Core\IOS\Network\MACUtils.cpp" />
     <ClCompile Include="Core\IOS\Network\NCD\Manage.cpp" />