implement file reading (unlocking the database)

- implement ReadField in PassStoreEntryPassword
- make WriteField static
- add ToString for LoginField, PassStoreEntryPassword & PassStoreEntryGroup
- fix bugs in OuterEncryptionReader and PassStoreFileAccessor
- change PassStoreFileAccessor.root type to PassStoreEntry

src/KeyKeeper/PasswordStore/Crypto/OuterEncryptionReader.cs

@@ -155,7 +155,10 @@ public class OuterEncryptionReader : Stream
         EraseCurrentChunk();
 
         int decrypted = 0, read = 0;
-        currentChunk = new byte[(encryptedData.Length + encryptedRemainderLength) / 16 * 16];
+        if (isCurrentChunkLast)
+            currentChunk = new byte[encryptedData.Length + encryptedRemainderLength];
+        else
+            currentChunk = new byte[(encryptedData.Length + encryptedRemainderLength) / 16 * 16];
         if (encryptedRemainderLength > 0 && encryptedData.Length >= 16 - encryptedRemainderLength)
         {
             encryptedData.Slice(0, 16 - encryptedRemainderLength)

src/KeyKeeper/PasswordStore/Crypto/PassStoreContentChunk.cs

@@ -40,8 +40,11 @@ public class PassStoreContentChunk
 
         try
         {
-            chunkLen = rd.ReadUInt16();
-            chunkLen = chunkLen | (rd.ReadByte() << 16);
+            byte[] chunkLenBytes = new byte[3];
+            if (str.Read(chunkLenBytes) < 3)
+                throw PassStoreFileException.UnexpectedEndOfFile;
+            chunkLen = BinaryPrimitives.ReadUInt16LittleEndian(new(chunkLenBytes, 0, 2));
+            chunkLen |= chunkLenBytes[2] << 16;
         }
         catch (EndOfStreamException)
         {
@@ -90,18 +93,17 @@ public class PassStoreContentChunk
     {
         BinaryReader rd = new(s);
         int chunkLen;
-        try
-        {
-            chunkLen = rd.ReadUInt16();
-            chunkLen = (chunkLen << 8) | rd.ReadByte();
-        }
-        catch (EndOfStreamException)
-        {
+
+        byte[] chunkLenBytes = new byte[3];
+        if (s.Read(chunkLenBytes) < 3)
             throw PassStoreFileException.UnexpectedEndOfFile;
-        }
+        chunkLen = BinaryPrimitives.ReadUInt16LittleEndian(new(chunkLenBytes, 0, 2));
+        chunkLen |= chunkLenBytes[2] << 16;
+
         chunkLen &= ~(1 << 23); // 23 бит имеет специальное значение
         byte[] chunk = new byte[3 + HMAC_SIZE + chunkLen];
-        if (s.Read(chunk) < chunk.Length)
+        Array.Copy(chunkLenBytes, chunk, 3);
+        if (s.Read(chunk, 3, HMAC_SIZE + chunkLen) < HMAC_SIZE + chunkLen)
         {
             throw PassStoreFileException.UnexpectedEndOfFile;
         }

src/KeyKeeper/PasswordStore/LoginField.cs

@@ -1,4 +1,5 @@
 using System;
+using static KeyKeeper.PasswordStore.FileFormatConstants;
 
 namespace KeyKeeper.PasswordStore;
 
@@ -7,4 +8,9 @@ public struct LoginField
     public byte Type;
     public Guid CustomFieldSubtype;
     public required string Value;
+
+    public override string ToString()
+    {
+        return string.Format("LoginField(type={0} {1} value={2})", Type, Type == LOGIN_FIELD_CUSTOM_ID ? "customtype=" + CustomFieldSubtype : "", Value);
+    }
 }

src/KeyKeeper/PasswordStore/PassStoreEntry.cs

@@ -1,6 +1,7 @@
 using System;
 using System.IO;
 using KeyKeeper.PasswordStore.Crypto;
+using static KeyKeeper.PasswordStore.FileFormatConstants;
 
 namespace KeyKeeper.PasswordStore;
 
@@ -33,5 +34,45 @@ public abstract class PassStoreEntry
         wr.Write(serializedEntry);
     }
 
+    public static PassStoreEntry ReadFromStream(Stream str)
+    {
+        BinaryReader rd = new(str);
+        try
+        {
+            rd.Read7BitEncodedInt();
+
+            byte[] uuidBuffer = new byte[16];
+            if (rd.Read(uuidBuffer) < 16)
+                throw PassStoreFileException.UnexpectedEndOfFile;
+            Guid id = new Guid(uuidBuffer);
+
+            ulong timestamp = FileFormatUtil.ReadVarUint16(str);
+            DateTime createdAt = DateTimeOffset.FromUnixTimeSeconds((long)timestamp).UtcDateTime;
+            timestamp = FileFormatUtil.ReadVarUint16(str);
+            DateTime modifiedAt = DateTimeOffset.FromUnixTimeSeconds((long)timestamp).UtcDateTime;
+
+            if (rd.Read(uuidBuffer) < 16)
+                throw PassStoreFileException.UnexpectedEndOfFile;
+            Guid iconType = new Guid(uuidBuffer);
+
+            string name = FileFormatUtil.ReadU16TaggedString(str);
+
+            byte entryType = rd.ReadByte();
+            if (entryType == ENTRY_GROUP_ID)
+            {
+                return PassStoreEntryGroup.ReadFromStream(str, id, createdAt, modifiedAt, iconType, name);
+            } else if (entryType == ENTRY_PASS_ID)
+            {
+                return PassStoreEntryPassword.ReadFromStream(str, id, createdAt, modifiedAt, iconType, name);
+            } else
+            {
+                throw PassStoreFileException.InvalidPassStoreEntry;
+            }
+        } catch (EndOfStreamException)
+        {
+            throw PassStoreFileException.UnexpectedEndOfFile;
+        }
+    }
+
     protected abstract byte[] InnerSerialize();
 }

src/KeyKeeper/PasswordStore/PassStoreEntryGroup.cs

@@ -36,7 +36,7 @@ public class PassStoreEntryGroup : PassStoreEntry, IPassStoreDirectory
         try
         {
             byte groupType = rd.ReadByte();
-            byte[] guidBuffer = new byte[8];
+            byte[] guidBuffer = new byte[16];
             Guid? customGroupSubtype = null;
             if (groupType == GROUP_TYPE_CUSTOM)
             {
@@ -71,6 +71,13 @@ public class PassStoreEntryGroup : PassStoreEntry, IPassStoreDirectory
         return ChildEntries.GetEnumerator();
     }
 
+    public override string ToString()
+    {
+        return string.Format(
+            "EntryGroup (id={0} name={1} chilren=[{2}])",
+            Id, Name, string.Join(", ", ChildEntries));
+    }
+
     protected override byte[] InnerSerialize()
     {
         MemoryStream str = new();

src/KeyKeeper/PasswordStore/PassStoreEntryPassword.cs

@@ -23,6 +23,31 @@ public class PassStoreEntryPassword : PassStoreEntry
         ExtraFields = extras ?? new();
     }
 
+    public static PassStoreEntry ReadFromStream(Stream str, Guid id, DateTime createdAt, DateTime modifiedAt, Guid iconType, string name)
+    {
+        BinaryReader rd = new(str);
+        try
+        {
+            LoginField username = ReadField(str);
+            LoginField password = ReadField(str);
+            PassStoreEntryPassword entry = new(id, createdAt, modifiedAt, iconType, name, username, password);
+            int extraFieldCount = rd.Read7BitEncodedInt();
+            for (; extraFieldCount > 0; extraFieldCount--)
+                entry.ExtraFields.Add(ReadField(str));
+            return entry;
+        } catch (EndOfStreamException)
+        {
+            throw PassStoreFileException.UnexpectedEndOfFile;
+        }
+    }
+
+    public override string ToString()
+    {
+        return string.Format(
+            "EntryPassword(id={0} name={1} fields=[first={2} second={3} extra={4}])",
+            Id, Name, Username, Password, string.Join(", ", ExtraFields));
+    }
+
     protected override byte[] InnerSerialize()
     {
         MemoryStream str = new();
@@ -36,11 +61,29 @@ public class PassStoreEntryPassword : PassStoreEntry
         return str.ToArray();
     }
 
-    private void WriteField(Stream str, LoginField field)
+    private static void WriteField(Stream str, LoginField field)
     {
         str.WriteByte(field.Type);
         if (field.Type == LOGIN_FIELD_CUSTOM_ID)
             str.Write(field.CustomFieldSubtype.ToByteArray());
         FileFormatUtil.WriteU16TaggedString(str, field.Value);
     }
+
+    private static LoginField ReadField(Stream str)
+    {
+        int t = str.ReadByte();
+        if (t == -1)
+            throw PassStoreFileException.UnexpectedEndOfFile;
+        LoginField field = new() { Value = "" };
+        field.Type = (byte)t;
+        if (t == LOGIN_FIELD_CUSTOM_ID)
+        {
+            byte[] uuidBuffer = new byte[16];
+            if (str.Read(uuidBuffer) < 16)
+                throw PassStoreFileException.UnexpectedEndOfFile;
+            field.CustomFieldSubtype = new Guid(uuidBuffer);
+        }
+        field.Value = FileFormatUtil.ReadU16TaggedString(str);
+        return field;
+    }
 }

src/KeyKeeper/PasswordStore/PassStoreFileAccessor.cs

@@ -20,7 +20,8 @@ public class PassStoreFileAccessor : IPassStore
 
     private string filename;
     private byte[]? key;
-    private IPassStoreDirectory? root;
+    private InnerEncryptionInfo? innerCrypto;
+    private PassStoreEntry? root;
 
     public PassStoreFileAccessor(string filename, bool create, StoreCreationOptions? createOptions)
     {
@@ -44,7 +45,7 @@ public class PassStoreFileAccessor : IPassStore
     {
         if (Locked)
             throw new InvalidOperationException();
-        return root!;
+        return (IPassStoreDirectory)root!;
     }
 
     public int GetTotalEntryCount()
@@ -58,7 +59,50 @@ public class PassStoreFileAccessor : IPassStore
 
         using FileStream file = new(filename, FileMode.Open, FileAccess.Read, FileShare.None);
         FileHeader hdr = FileHeader.ReadFrom(file);
-        Console.WriteLine(hdr); // debug
+
+        file.Seek((file.Position + 4096 - 1) / 4096 * 4096, SeekOrigin.Begin);
+
+        key.Salt = hdr.PreSalt;
+        this.key = hdr.KdfInfo.GetKdf().Derive(key, 32);
+        using OuterEncryptionReader cryptoReader = new(file, this.key, ((OuterAesHeader)hdr.OuterCryptoHeader).InitVector);
+        using BinaryReader rd = new(cryptoReader);
+
+        {
+            if (rd.ReadUInt32() != FILE_FIELD_BEGIN)
+                throw PassStoreFileException.InvalidBeginMarker;
+            Span<byte> marker = stackalloc byte[8];
+            if (rd.Read(marker) < 8)
+                throw PassStoreFileException.UnexpectedEndOfFile;
+            if (!marker.SequenceEqual(BEGIN_MARKER))
+                throw PassStoreFileException.InvalidBeginMarker;
+        }
+
+        while (true)
+        {
+            try
+            {
+                uint fileField = rd.ReadUInt32();
+                bool end = false;
+                switch (fileField)
+                {
+                    case FILE_FIELD_INNER_CRYPTO:
+                        ReadInnerCryptoInfo(cryptoReader);
+                        break;
+                    case FILE_FIELD_CONFIG:
+                        break;
+                    case FILE_FIELD_STORE:
+                        this.root = PassStoreEntry.ReadFromStream(cryptoReader);
+                        break;
+                    case FILE_FIELD_END:
+                        end = true;
+                        break;
+                }
+                if (end) break;
+            } catch (EndOfStreamException)
+            {
+                throw PassStoreFileException.UnexpectedEndOfFile;
+            }
+        }
     }
 
     public void Lock()
@@ -153,7 +197,10 @@ public class PassStoreFileAccessor : IPassStore
         wr.Write(FILE_FIELD_CONFIG);
 
         wr.Write(FILE_FIELD_STORE);
-        root = (IPassStoreDirectory) WriteInitialStoreTree(cryptoWriter);
+        root = WriteInitialStoreTree(cryptoWriter);
+
+        wr.Write(FILE_FIELD_END);
+
         cryptoWriter.Flush();
         cryptoWriter.Dispose();
     }
@@ -173,6 +220,17 @@ public class PassStoreFileAccessor : IPassStore
         return root;
     }
 
+    private InnerEncryptionInfo ReadInnerCryptoInfo(Stream str)
+    {
+        byte[] key = new byte[32];
+        byte[] iv = new byte[16];
+        if (str.Read(key) < 32)
+            throw PassStoreFileException.UnexpectedEndOfFile;
+        if (str.Read(iv) < 16)
+            throw PassStoreFileException.UnexpectedEndOfFile;
+        return new(key, iv);
+    }
+
     record FileHeader (
         ushort FileVersionMajor,
         ushort FileVersionMinor,
@@ -328,4 +386,10 @@ public class PassStoreFileAccessor : IPassStore
             return new AesKdf(Rounds, Seed);
         }
     }
+
+    record struct InnerEncryptionInfo(
+        byte[] Key,
+        byte[] Iv
+    )
+    {}
 }

src/KeyKeeper/PasswordStore/PassStoreFileException.cs

@@ -9,6 +9,8 @@ public class PassStoreFileException : Exception
     public static readonly PassStoreFileException UnsupportedVersion = new("unsupported format version");
     public static readonly PassStoreFileException InvalidCryptoHeader = new("invalid encryption header");
     public static readonly PassStoreFileException ContentHMACMismatch = new("content HMAC mismatch");
+    public static readonly PassStoreFileException InvalidPassStoreEntry = new("invalid store entry");
+    public static readonly PassStoreFileException InvalidBeginMarker = new("invalid marker of the beginning of data");
 
     public PassStoreFileException(string description): base(description)
     {