diff --git a/dependencies/tlibc b/dependencies/tlibc
index ea6c20f..0d422cd 160000
--- a/dependencies/tlibc
+++ b/dependencies/tlibc
@@ -1 +1 @@
-Subproject commit ea6c20f430f4536631f379697ae56fc8b5fd5d17
+Subproject commit 0d422cd7e591795398649ff5cdb7fa2b5679e92d
diff --git a/dependencies/tlibtoml b/dependencies/tlibtoml
index a0e280d..bd38585 160000
--- a/dependencies/tlibtoml
+++ b/dependencies/tlibtoml
@@ -1 +1 @@
-Subproject commit a0e280d77b6d8967239b14915609eef422f6ba0b
+Subproject commit bd38585b35937a977b5f3e048be56faed38b2e16
diff --git a/include/tcp-chat/common_constants.h b/include/tcp-chat/common_constants.h
index e77faab..d6d353c 100644
--- a/include/tcp-chat/common_constants.h
+++ b/include/tcp-chat/common_constants.h
@@ -18,3 +18,4 @@
 #define CHANNEL_DESC_SIZE_MAX 1023
 #define MESSAGE_SIZE_MIN 1
 #define MESSAGE_SIZE_MAX 4000
+#define MESSAGE_BLOCK_SIZE (64*1024)
\ No newline at end of file
diff --git a/src/cli/ClientCLI/ClientCLI.c b/src/cli/ClientCLI/ClientCLI.c
index 7a864dc..b65c4f4 100644
--- a/src/cli/ClientCLI/ClientCLI.c
+++ b/src/cli/ClientCLI/ClientCLI.c
@@ -43,7 +43,7 @@ void ClientCLI_destroy(ClientCLI* self){
     HashMap_destroy(&self->servers.addr_id_map);
 }
 void ClientCLI_construct(ClientCLI* self){
-    memset(self, 0, sizeof(*self));
+    zeroStruct(self);
 }
 
 Result(void) ClientCLI_run(ClientCLI* self) {
@@ -326,7 +326,7 @@ static Result(void) ClientCLI_openUserDB(ClientCLI* self){
 
     // Load servers table
     try(self->servers.table, p,
-        idb_getOrCreateTable(self->db, STR("servers"), sizeof(ServerInfo), false)
+        idb_getOrCreateTable(self->db, str_null, STR("servers"), sizeof(ServerInfo), false)
     );
     
     // Lock table until this function returns.
@@ -362,7 +362,7 @@ static Result(ServerInfo*) ClientCLI_saveServerInfo(ClientCLI* self,
 
     // create new server info
     ServerInfo server;
-    memset(&server, 0, sizeof(ServerInfo));
+    zeroStruct(&server);
     // address
     if(addr.len > HOSTADDR_SIZE_MAX)
         addr.len = HOSTADDR_SIZE_MAX;
diff --git a/src/client/ServerConnection.c b/src/client/ServerConnection.c
index 8786dee..8b5deeb 100644
--- a/src/client/ServerConnection.c
+++ b/src/client/ServerConnection.c
@@ -18,7 +18,7 @@ Result(ServerConnection*) ServerConnection_open(Client* client, cstr server_addr
     Deferral(16);
 
     ServerConnection* conn = (ServerConnection*)malloc(sizeof(ServerConnection));
-    memset(conn, 0, sizeof(*conn));
+    zeroStruct(conn);
     bool success = false;
     Defer(if(!success) ServerConnection_close(conn));
 
diff --git a/src/client/client.c b/src/client/client.c
index a1a3ced..2709246 100644
--- a/src/client/client.c
+++ b/src/client/client.c
@@ -15,7 +15,7 @@ Result(Client*) Client_create(str username, str password){
     Deferral(16);
 
     Client* self = (Client*)malloc(sizeof(Client));
-    memset(self, 0, sizeof(Client));
+    zeroStruct(self);
     bool success = false;
     Defer(if(!success) Client_free(self));
 
diff --git a/src/cryptography/AES.c b/src/cryptography/AES.c
index 28201a8..0a12840 100755
--- a/src/cryptography/AES.c
+++ b/src/cryptography/AES.c
@@ -55,7 +55,7 @@ Result(u32) AESBlockEncryptor_encrypt(AESBlockEncryptor* ptr,
     __Array_writeNext(&dst, ptr->iv, __AES_BLOCK_IV_SIZE);
 
     EncryptedBlockHeader header;
-    memset(&header, 0, sizeof(header));
+    zeroStruct(&header);
     memcpy(header.key_checksum, ptr->key_checksum, __AES_BLOCK_KEY_CHECKSUM_SIZE);
     header.padding_size = (16 - src.len % 16) % 16;
     // write header to buffer
diff --git a/src/db/idb.c b/src/db/idb.c
index f515858..2daffc4 100644
--- a/src/db/idb.c
+++ b/src/db/idb.c
@@ -2,6 +2,7 @@
 #include "tlibc/magic.h"
 #include "tlibc/filesystem.h"
 #include "tlibc/collections/HashMap.h"
+#include "tlibc/string/StringBuilder.h"
 #include "cryptography/AES.h"
 #include <pthread.h>
 
@@ -216,11 +217,12 @@ void idb_close(IncrementalDB* db){
 
 Result(IncrementalDB*) idb_open(str db_dir, NULLABLE(Array(u8) aes_key)){
     Deferral(16);
+    try_assert(db_dir.len > 0);
     try_assert(aes_key.len == 0 || aes_key.len == 16 || aes_key.len == 24 || aes_key.len == 32);
 
     IncrementalDB* db = (IncrementalDB*)malloc(sizeof(IncrementalDB));
     // value of *db must be set to zero or behavior of idb_close will be undefined
-    memset(db, 0, sizeof(IncrementalDB));
+    zeroStruct(db);
     // if object construction fails, destroy incomplete object
     bool success = false;
     Defer(if(!success) idb_close(db));
@@ -255,7 +257,7 @@ void idb_unlockTable(Table* t){
 }
 
 
-Result(Table*) idb_getOrCreateTable(IncrementalDB* db, str table_name, u32 row_size, bool lock_db){
+Result(Table*) idb_getOrCreateTable(IncrementalDB* db, str subdir, str table_name, u32 row_size, bool lock_db){
     Deferral(16);
 
     if(lock_db){
@@ -274,7 +276,7 @@ Result(Table*) idb_getOrCreateTable(IncrementalDB* db, str table_name, u32 row_s
 
     Table* t = (Table*)malloc(sizeof(Table));
     // value of *t must be set to zero or behavior of Table_close will be undefined
-    memset(t, 0, sizeof(Table));
+    zeroStruct(t);
     // if object construction fails, destroy incomplete object
     bool success = false;
     Defer(if(!success) Table_close(t));
@@ -282,10 +284,27 @@ Result(Table*) idb_getOrCreateTable(IncrementalDB* db, str table_name, u32 row_s
     t->db = db;
     try_stderrcode(pthread_mutex_init(&t->mutex, NULL));
     t->name = str_copy(table_name);
-    t->table_file_path = str_from_cstr(
-        strcat_malloc(db->db_dir.data, path_seps, t->name.data, ".idb-table"));
-    t->changes_file_path = str_from_cstr(
-        strcat_malloc(db->db_dir.data, path_seps, t->name.data, ".idb-changes"));
+
+    // set file paths
+    StringBuilder sb = StringBuilder_alloc(256);
+    Defer(StringBuilder_destroy(&sb));
+    StringBuilder_append_str(&sb, db->db_dir);
+    StringBuilder_append_char(&sb, path_sep);
+    if(subdir.len != 0){
+        StringBuilder_append_str(&sb, subdir);
+        try_void(dir_create(StringBuilder_getStr(&sb).data));
+        StringBuilder_append_char(&sb, path_sep);
+    }
+    StringBuilder_append_str(&sb, t->name);
+    // table file
+    str table_file_ext = STR(".idb-table");
+    StringBuilder_append_str(&sb, table_file_ext);
+    t->table_file_path = str_copy(StringBuilder_getStr(&sb));
+    // changes file
+    str changes_file_ext = STR(".idb-changes");
+    StringBuilder_removeFromEnd(&sb, table_file_ext.len);
+    StringBuilder_append_str(&sb, changes_file_ext);
+    t->changes_file_path = str_copy(StringBuilder_getStr(&sb));
 
     bool table_file_exists = file_exists(t->table_file_path.data);
 
diff --git a/src/db/idb.h b/src/db/idb.h
index c51fd6c..f752766 100644
--- a/src/db/idb.h
+++ b/src/db/idb.h
@@ -30,7 +30,7 @@ void idb_lockTable(Table* t);
 void idb_unlockTable(Table* t);
 
 
-Result(Table*) idb_getOrCreateTable(IncrementalDB* db, str table_name, u32 row_size, bool lock_db);
+Result(Table*) idb_getOrCreateTable(IncrementalDB* db, NULLABLE(str) subdir, str table_name, u32 row_size, bool lock_db);
 
 Result(void) idb_getRows(Table* t, u64 start_from_id, void* dst, u64 count, bool lock_table);
 #define idb_getRow(T, ID, DST, LOCK) idb_getRows(T, ID, DST, 1, LOCK)
diff --git a/src/db/tables.h b/src/db/tables.h
index 42ad2f7..dc2d197 100644
--- a/src/db/tables.h
+++ b/src/db/tables.h
@@ -32,6 +32,7 @@ typedef struct ChannelInfo {
     char desc[CHANNEL_DESC_SIZE_MAX + 1];
 } ATTRIBUTE_ALIGNED(4*1024) ChannelInfo;
 
+
 // not a table
 typedef struct MessageMeta {
     /* 
@@ -50,12 +51,13 @@ typedef struct MessageMeta {
 // Stores some number of messages. Look in MessageBlockMeta to see how much.
 typedef struct MessageBlock {
     /* ((sequence MessageMeta), (sequence binary-data)) */
-    u8 data[64*1024 - 4];
+    u8 data[MESSAGE_BLOCK_SIZE];
 } ATTRIBUTE_ALIGNED(64) MessageBlock;
 
 // is used to find in which MessageBlock a message is stored
 typedef struct MessageBlockMeta {
-    u64 message_id_first;
+    u64 first_message_id;
     u32 messages_count;
+    u32 data_size;
 } ATTRIBUTE_ALIGNED(16) MessageBlockMeta;
 
diff --git a/src/network/tcp-chat-protocol/constant.c b/src/network/tcp-chat-protocol/constant.c
index c15a91b..9d0f2d7 100644
--- a/src/network/tcp-chat-protocol/constant.c
+++ b/src/network/tcp-chat-protocol/constant.c
@@ -29,7 +29,7 @@ Result(void) PacketHeader_validateContentSize(PacketHeader* ptr, u64 expected_si
 }
 
 void PacketHeader_construct(PacketHeader* ptr, u8 protocol_version, u16 type, u64 content_size){
-    memset(ptr, 0, sizeof(*ptr));
+    zeroStruct(ptr);
     ptr->magic.n = PacketHeader_MAGIC.n;
     ptr->protocol_version = protocol_version;
     ptr->type = type;
diff --git a/src/network/tcp-chat-protocol/v1.c b/src/network/tcp-chat-protocol/v1.c
index 5d88c51..2758abf 100644
--- a/src/network/tcp-chat-protocol/v1.c
+++ b/src/network/tcp-chat-protocol/v1.c
@@ -45,7 +45,7 @@ str validateUsername_str(str username){
 
 void ErrorMessage_construct(ErrorMessage* ptr, PacketHeader* header, u32 msg_size){
     _PacketHeader_construct(ErrorMessage);
-    memset(ptr, 0, sizeof(*ptr));
+    zeroStruct(ptr);
     ptr->msg_size = msg_size;
 }
 
@@ -54,7 +54,7 @@ Result(void) ClientHandshake_tryConstruct(ClientHandshake* ptr, PacketHeader* he
 {
     Deferral(1);
     _PacketHeader_construct(ClientHandshake);
-    memset(ptr, 0, sizeof(*ptr));
+    zeroStruct(ptr);
 
     try_assert(session_key.len == sizeof(ptr->session_key));
     memcpy(ptr->session_key, session_key.data, session_key.len);
@@ -66,7 +66,7 @@ void ServerHandshake_construct(ServerHandshake* ptr, PacketHeader* header,
     u64 session_id)
 {
     _PacketHeader_construct(ServerHandshake);
-    memset(ptr, 0, sizeof(*ptr));
+    zeroStruct(ptr);
     ptr->session_id = session_id;
 }
 
@@ -74,7 +74,7 @@ void ServerPublicInfoRequest_construct(ServerPublicInfoRequest *ptr, PacketHeade
     ServerPublicInfo property)
 {
     _PacketHeader_construct(ServerPublicInfoRequest);
-    memset(ptr, 0, sizeof(*ptr));
+    zeroStruct(ptr);
     ptr->property = property;
 }
 
@@ -82,7 +82,7 @@ void ServerPublicInfoResponse_construct(ServerPublicInfoResponse* ptr, PacketHea
     u32 data_size)
 {
     _PacketHeader_construct(ServerPublicInfoResponse);
-    memset(ptr, 0, sizeof(*ptr));
+    zeroStruct(ptr);
     ptr->data_size = data_size;
 }
 
@@ -91,7 +91,7 @@ Result(void) LoginRequest_tryConstruct(LoginRequest *ptr, PacketHeader* header,
 {
     Deferral(1);
     _PacketHeader_construct(LoginRequest);
-    memset(ptr, 0, sizeof(*ptr));
+    zeroStruct(ptr);
 
     str name_error_str = validateUsername_str(username);
     if(name_error_str.data){
@@ -109,7 +109,7 @@ void LoginResponse_construct(LoginResponse* ptr, PacketHeader* header,
     u64 user_id, u64 landing_channel_id)
 {
     _PacketHeader_construct(LoginResponse);
-    memset(ptr, 0, sizeof(*ptr));
+    zeroStruct(ptr);
 
     ptr->user_id = user_id;
     ptr->landing_channel_id = landing_channel_id;
@@ -120,7 +120,7 @@ Result(void) RegisterRequest_tryConstruct(RegisterRequest *ptr, PacketHeader* he
 {
     Deferral(1);
     _PacketHeader_construct(RegisterRequest);
-    memset(ptr, 0, sizeof(*ptr));
+    zeroStruct(ptr);
 
     str name_error_str = validateUsername_str(username);
     if(name_error_str.data){
@@ -138,6 +138,43 @@ void RegisterResponse_construct(RegisterResponse *ptr, PacketHeader* header,
     u64 user_id)
 {
     _PacketHeader_construct(RegisterResponse);
-    memset(ptr, 0, sizeof(*ptr));
+    zeroStruct(ptr);
     ptr->user_id = user_id;
 }
+
+void SendMessageRequest_construct(SendMessageRequest *ptr, PacketHeader *header,
+    u64 channel_id, u16 data_size)
+{
+    _PacketHeader_construct(SendMessageRequest);
+    zeroStruct(ptr);
+    ptr->channel_id = channel_id;
+    ptr->data_size = data_size;
+}
+
+void SendMessageResponse_construct(SendMessageResponse *ptr, PacketHeader *header,
+    u64 message_id, DateTime receiving_time_utc)
+{
+    _PacketHeader_construct(SendMessageResponse);
+    zeroStruct(ptr);
+    ptr->message_id = message_id;
+    ptr->receiving_time_utc = receiving_time_utc;
+}
+
+void GetMessageBlockRequest_construct(GetMessageBlockRequest *ptr, PacketHeader *header,
+    u64 first_message_id, u32 messages_count)
+{
+    _PacketHeader_construct(GetMessageBlockRequest);
+    zeroStruct(ptr);
+    ptr->first_message_id = first_message_id;
+    ptr->messages_count = messages_count;
+}
+
+void GetMessageBlockResponse_construct(GetMessageBlockResponse *ptr, PacketHeader *header,
+    u64 first_message_id, u32 messages_count, u32 data_size)
+{
+    _PacketHeader_construct(GetMessageBlockResponse);
+    zeroStruct(ptr);
+    ptr->first_message_id = first_message_id;
+    ptr->messages_count = messages_count;
+    ptr->data_size = data_size;
+}
diff --git a/src/network/tcp-chat-protocol/v1.h b/src/network/tcp-chat-protocol/v1.h
index 2c0f92e..d45f27a 100644
--- a/src/network/tcp-chat-protocol/v1.h
+++ b/src/network/tcp-chat-protocol/v1.h
@@ -33,6 +33,10 @@ typedef enum PacketType {
     PacketType_LoginResponse,
     PacketType_RegisterRequest,
     PacketType_RegisterResponse,
+    PacketType_SendMessageRequest,
+    PacketType_SendMessageResponse,
+    PacketType_GetMessageBlockRequest,
+    PacketType_GetMessageBlockResponse,
 } ATTRIBUTE_PACKED PacketType;
 
 
@@ -140,21 +144,21 @@ void SendMessageResponse_construct(SendMessageResponse* ptr, PacketHeader* heade
 
 
 typedef struct GetMessageBlockRequest {
-    u64 message_id_first;
+    u64 first_message_id;
     u32 messages_count;
 } ALIGN_PACKET_STRUCT GetMessageBlockRequest;
 
 void GetMessageBlockRequest_construct(GetMessageBlockRequest* ptr, PacketHeader* header,
-    u64 message_id_first, u32 messages_count);
+    u64 first_message_id, u32 messages_count);
 
 
 typedef struct GetMessageBlockResponse {
-    u64 message_id_first;
+    u64 first_message_id;
     u32 messages_count;
     u32 data_size;
     /* stream of size data_size : ((sequence MessageMeta), (sequence binary-data)) */
 } ALIGN_PACKET_STRUCT GetMessageBlockResponse;
 
 void GetMessageBlockResponse_construct(GetMessageBlockResponse* ptr, PacketHeader* header,
-    u32 data_size);
+    u64 first_message_id, u32 messages_count, u32 data_size);
 
diff --git a/src/server/Channel.c b/src/server/Channel.c
new file mode 100644
index 0000000..125988a
--- /dev/null
+++ b/src/server/Channel.c
@@ -0,0 +1,151 @@
+#include "server_internal.h"
+#include "tlibc/string/StringBuilder.h"
+#include "tlibc/filesystem.h"
+
+void Channel_free(Channel* self){
+    if(!self)
+        return;
+    str_destroy(self->name);
+    str_destroy(self->description);
+    List_MessageBlockMeta_destroy(&self->messages.blocks_meta_list);
+    LList_MessageBlock_destroy(&self->messages.blocks_queue);
+    free(self);
+}
+
+Result(Channel*) Channel_create(u64 chan_id, str name, str description,
+    IncrementalDB* db, bool lock_db)
+{
+    Deferral(8);
+    
+    Channel* self = (Channel*)malloc(sizeof(Channel));
+    zeroStruct(self);
+    bool success = false;
+    Defer(if(!success) Channel_free(self));
+
+    self->id = chan_id;
+    try_assert(name.len >= CHANNEL_NAME_SIZE_MIN && name.len <= CHANNEL_NAME_SIZE_MAX);
+    self->name = str_copy(name);
+    try_assert(description.len <= CHANNEL_DESC_SIZE_MAX);
+    self->description = str_copy(description);
+
+    if(lock_db){
+        idb_lockDB(db);
+        Defer(idb_unlockDB(db));
+    }
+    
+    StringBuilder sb = StringBuilder_alloc(CHANNEL_NAME_SIZE_MAX + 32 + 1);
+    Defer(StringBuilder_destroy(&sb));
+    StringBuilder_append_str(&sb, STR("channels"));
+    StringBuilder_append_char(&sb, path_sep);
+    StringBuilder_append_str(&sb, name);
+
+    str subdir = str_copy(StringBuilder_getStr(&sb));
+    Defer(str_destroy(subdir));
+    str message_blocks_str = STR("message_blocks");
+    str message_blocks_meta_str = STR("message_blocks_meta");
+    
+    StringBuilder_removeFromEnd(&sb, -1);
+    StringBuilder_append_str(&sb, name);
+    StringBuilder_append_char(&sb, '_');
+    StringBuilder_append_str(&sb, message_blocks_str);
+    try(self->messages.blocks_table, p, 
+        idb_getOrCreateTable(db, subdir, StringBuilder_getStr(&sb), sizeof(MessageBlock), false)
+    );
+    idb_lockTable(self->messages.blocks_table);
+    Defer(idb_unlockTable(self->messages.blocks_table));
+
+    
+    StringBuilder_removeFromEnd(&sb, message_blocks_str.len);
+    StringBuilder_append_str(&sb, message_blocks_meta_str);
+    try(self->messages.blocks_meta_table, p, 
+        idb_getOrCreateTable(db, subdir, StringBuilder_getStr(&sb), sizeof(MessageBlock), false)
+    );
+    idb_lockTable(self->messages.blocks_meta_table);
+    Defer(idb_unlockTable(self->messages.blocks_meta_table));
+
+    // load whole message_blocks_meta table to list
+    try_void(
+        idb_createListFromTable(self->messages.blocks_meta_table, (void*)&self->messages.blocks_meta_list, false)
+    );
+    
+    // load N last blocks to the queue
+    self->messages.blocks_queue = LList_construct(MessageBlock, NULL);
+    u64 message_blocks_count = self->messages.blocks_meta_list.len;
+    u64 first_block_id = 0;
+    if(message_blocks_count > MESSAGE_BLOCKS_CACHE_COUNT)
+        first_block_id = message_blocks_count - MESSAGE_BLOCKS_CACHE_COUNT;
+    for(u64 id = first_block_id; id < message_blocks_count; id++){
+        LLNode(MessageBlock)* node = LLNode_MessageBlock_createZero();
+        LList_MessageBlock_insertAfter(
+            &self->messages.blocks_queue,
+            self->messages.blocks_queue.last,
+            node
+        );
+        try_void(idb_getRow(self->messages.blocks_table, id, node->value.data, false));
+    }
+
+    if(self->messages.blocks_meta_list.len > 0){
+        MessageBlockMeta last_block_meta = self->messages.blocks_meta_list.data[self->messages.blocks_meta_list.len - 1];
+        self->messages.count = last_block_meta.first_message_id + last_block_meta.messages_count - 1;
+    }
+    else {
+        self->messages.count = 0;
+    }
+
+    success = true;
+    Return RESULT_VALUE(p, self);
+}
+
+
+Result(void) Channel_saveMessage(Channel* self, Array(u8) message_data, u64 sender_id,
+    MessageMeta* out_message_meta)
+{
+    Deferral(1);
+
+    // create new block if message won't fit in the last existing
+    MessageBlockMeta* incomplete_block_meta = self->messages.blocks_meta_list.data + self->messages.blocks_meta_list.len;
+    u64 new_message_id = incomplete_block_meta->first_message_id + incomplete_block_meta->messages_count;
+    u32 message_size_in_block = sizeof(MessageMeta) + ALIGN_TO(message_data.len, 8);
+    if(incomplete_block_meta->data_size + message_size_in_block > MESSAGE_BLOCK_SIZE){
+        // create new MessageBlockMeta
+        incomplete_block_meta = List_MessageBlockMeta_expand(&self->messages.blocks_meta_list, 1);
+        incomplete_block_meta->first_message_id = new_message_id;
+        incomplete_block_meta->messages_count = 0;
+        incomplete_block_meta->data_size = 0;
+        // create new MessageBlock
+        LList_MessageBlock_insertAfter(
+            &self->messages.blocks_queue,
+            self->messages.blocks_queue.last, 
+            LLNode_MessageBlock_createZero());
+        //TODO: save to DB
+    }
+    
+    // copy message to message block
+    out_message_meta->magic = MESSAGE_MAGIC;
+    out_message_meta->data_size = message_data.len;
+    out_message_meta->id = new_message_id;
+    out_message_meta->sender_id = sender_id;
+    DateTime_getUTC(&out_message_meta->receiving_time_utc);
+
+    MessageBlock* incomplete_block = &self->messages.blocks_queue.last->value;
+    u8* data_ptr = incomplete_block->data + incomplete_block_meta->data_size;
+    memcpy(data_ptr, out_message_meta, sizeof(MessageMeta));
+    data_ptr += sizeof(MessageMeta);
+    memcpy(data_ptr, message_data.data, message_data.len);
+
+    Return RESULT_VOID;
+}
+
+// Result(void) Channel_loadMessage(Channel* self, u64 id, 
+//     MessageMeta* out_message_meta, u8* out_data)
+// {
+//     Deferral(1);
+//     Return RESULT_VOID;
+// }
+
+// Result(void) Channel_loadMessageBlock(Channel* self, u64 fisrt_message_id, u32 count,
+//     MessageBlockMeta* out_message_meta, MessageBlock* out_block)
+// {
+//     Deferral(1);
+//     Return RESULT_VOID;
+// }
diff --git a/src/server/ClientConnection.c b/src/server/ClientConnection.c
index 11123ad..39d22ad 100644
--- a/src/server/ClientConnection.c
+++ b/src/server/ClientConnection.c
@@ -14,7 +14,7 @@ Result(ClientConnection*) ClientConnection_accept(ConnectionHandlerArgs* args)
     Deferral(8);
 
     ClientConnection* conn = (ClientConnection*)malloc(sizeof(ClientConnection));
-    memset(conn, 0, sizeof(*conn));
+    zeroStruct(conn);
     bool success = false;
     Defer(if(!success) ClientConnection_close(conn));
 
@@ -22,6 +22,7 @@ Result(ClientConnection*) ClientConnection_accept(ConnectionHandlerArgs* args)
     conn->client_end = args->client_end;
     conn->session_id = args->session_id;
     conn->authorized = false;
+    conn->user_id = -1;
     conn->session_key = Array_u8_alloc(AES_SESSION_KEY_SIZE);
     // correct session key will be received from client later
     Array_u8_memset(&conn->session_key, 0);
diff --git a/src/server/responses/GetMessageBlock.c b/src/server/responses/GetMessageBlock.c
index d2ab40e..2379308 100644
--- a/src/server/responses/GetMessageBlock.c
+++ b/src/server/responses/GetMessageBlock.c
@@ -1,7 +1,8 @@
 #include "responses.h"
 
-#define LOGGER conn->server->logger
-#define LOG_FUNC conn->server->log_func
+#define srv conn->server
+#define LOGGER srv->logger
+#define LOG_FUNC srv->log_func
 #define LOG_CONTEXT log_ctx
 
 declare_RequestHandler(GetMessageBlock)
@@ -14,6 +15,7 @@ declare_RequestHandler(GetMessageBlock)
     try_void(PacketHeader_validateContentSize(req_head, sizeof(req)));
     try_void(EncryptedSocketTCP_recvStruct(&conn->sock, &req));
 
+    (void)res_head;
     // send response
     // GetMessageBlockResponse res;
     // GetMessageBlockResponse_construct(&res, res_head, );
diff --git a/src/server/responses/Login.c b/src/server/responses/Login.c
index f2102bd..68df2da 100644
--- a/src/server/responses/Login.c
+++ b/src/server/responses/Login.c
@@ -1,7 +1,8 @@
 #include "responses.h"
 
-#define LOGGER conn->server->logger
-#define LOG_FUNC conn->server->log_func
+#define srv conn->server
+#define LOGGER srv->logger
+#define LOG_FUNC srv->log_func
 #define LOG_CONTEXT log_ctx
 
 declare_RequestHandler(Login)
@@ -35,15 +36,15 @@ declare_RequestHandler(Login)
     }
 
     // lock users cache
-    idb_lockTable(conn->server->users.table);
+    idb_lockTable(srv->users.table);
     bool unlocked_users_cache_mutex = false;
     Defer(
         if(!unlocked_users_cache_mutex)
-            idb_unlockTable(conn->server->users.table)
+            idb_unlockTable(srv->users.table)
     );
     
     // try get id from name cache
-    u64* id_ptr = HashMap_tryGetPtr(&conn->server->users.username_id_map, username_str);
+    u64* id_ptr = HashMap_tryGetPtr(&srv->users.name_id_map, username_str);
     if(id_ptr == NULL){
         try_void(sendErrorMessage_f(log_ctx, conn, res_head,
             LogSeverity_Warn,
@@ -55,8 +56,8 @@ declare_RequestHandler(Login)
     u64 user_id = *id_ptr;
 
     // get user by id
-    try_assert(user_id < conn->server->users.cache_list.len);
-    UserInfo* u = conn->server->users.cache_list.data + user_id;
+    try_assert(user_id < srv->users.list.len);
+    UserInfo* u = srv->users.list.data + user_id;
 
     // validate token hash
     if(memcmp(req.token, u->token, sizeof(req.token)) != 0){
@@ -68,16 +69,17 @@ declare_RequestHandler(Login)
     }
 
     // manually unlock mutex
-    idb_unlockTable(conn->server->users.table);
+    idb_unlockTable(srv->users.table);
     unlocked_users_cache_mutex = true;
 
     // authorize
     conn->authorized = true;
+    conn->user_id = user_id;
     logInfo("authorized user '%s'", username_str.data);
 
     // send response
     LoginResponse res;
-    LoginResponse_construct(&res, res_head, user_id, conn->server->landing_channel_id);
+    LoginResponse_construct(&res, res_head, user_id, srv->landing_channel_id);
     try_void(EncryptedSocketTCP_sendStruct(&conn->sock, res_head));
     try_void(EncryptedSocketTCP_sendStruct(&conn->sock, &res));
     
diff --git a/src/server/responses/Register.c b/src/server/responses/Register.c
index 4647fa5..243485e 100644
--- a/src/server/responses/Register.c
+++ b/src/server/responses/Register.c
@@ -1,7 +1,8 @@
 #include "responses.h"
 
-#define LOGGER conn->server->logger
-#define LOG_FUNC conn->server->log_func
+#define srv conn->server
+#define LOGGER srv->logger
+#define LOG_FUNC srv->log_func
 #define LOG_CONTEXT log_ctx
 
 declare_RequestHandler(Register)
@@ -35,16 +36,16 @@ declare_RequestHandler(Register)
     }
 
     // lock users cache
-    idb_lockTable(conn->server->users.table);
+    idb_lockTable(srv->users.table);
     bool unlocked_users_cache_mutex = false;
     // unlock mutex on error catch
     Defer(
         if(!unlocked_users_cache_mutex)
-            idb_unlockTable(conn->server->users.table)
+            idb_unlockTable(srv->users.table)
     );
 
     // check if name is taken
-    if(HashMap_tryGetPtr(&conn->server->users.username_id_map, username_str) != NULL){
+    if(HashMap_tryGetPtr(&srv->users.name_id_map, username_str) != NULL){
         try_void(sendErrorMessage_f(log_ctx, conn, res_head,
             LogSeverity_Warn,
             "Username '%s' already exists", 
@@ -54,7 +55,7 @@ declare_RequestHandler(Register)
 
     // initialize new user
     UserInfo user;
-    memset(&user, 0, sizeof(UserInfo));
+    zeroStruct(&user);
 
     user.name_len = username_str.len;
     memcpy(user.name, username_str.data, user.name_len);
@@ -65,14 +66,14 @@ declare_RequestHandler(Register)
     
     // save new user to db and cache
     try(u64 user_id, u, 
-        idb_pushRow(conn->server->users.table, &user, false)
+        idb_pushRow(srv->users.table, &user, false)
     );
-    try_assert(user_id == conn->server->users.cache_list.len);
-    List_UserInfo_pushMany(&conn->server->users.cache_list, &user, 1);
-    try_assert(HashMap_tryPush(&conn->server->users.username_id_map, username_str, &user_id));
+    try_assert(user_id == srv->users.list.len);
+    List_UserInfo_pushMany(&srv->users.list, &user, 1);
+    try_assert(HashMap_tryPush(&srv->users.name_id_map, username_str, &user_id));
     
     // manually unlock mutex
-    idb_unlockTable(conn->server->users.table);
+    idb_unlockTable(srv->users.table);
     unlocked_users_cache_mutex = true;
 
     logInfo("registered user '%s'", username_str.data);
diff --git a/src/server/responses/SendMessage.c b/src/server/responses/SendMessage.c
index 4b11245..04477e5 100644
--- a/src/server/responses/SendMessage.c
+++ b/src/server/responses/SendMessage.c
@@ -1,7 +1,8 @@
 #include "responses.h"
 
-#define LOGGER conn->server->logger
-#define LOG_FUNC conn->server->log_func
+#define srv conn->server
+#define LOGGER srv->logger
+#define LOG_FUNC srv->log_func
 #define LOG_CONTEXT log_ctx
 
 declare_RequestHandler(SendMessage)
@@ -14,6 +15,14 @@ declare_RequestHandler(SendMessage)
     try_void(PacketHeader_validateContentSize(req_head, sizeof(req)));
     try_void(EncryptedSocketTCP_recvStruct(&conn->sock, &req));
     
+    if(!conn->authorized){
+        try_void(sendErrorMessage(log_ctx, conn, res_head,
+            LogSeverity_Warn,
+            STR("is not authorized")
+        ));
+        Return RESULT_VOID;
+    }
+
     if(req.data_size < MESSAGE_SIZE_MIN || req.data_size > MESSAGE_SIZE_MAX){
         try_void(sendErrorMessage_f(log_ctx, conn, res_head,
             LogSeverity_Warn,
@@ -28,16 +37,24 @@ declare_RequestHandler(SendMessage)
     Array(u8) message_data = Array_u8_alloc(req.data_size);
     try_void(EncryptedSocketTCP_recv(&conn->sock, message_data, SocketRecvFlag_WholeBuffer));
     
-    for(u16 i = 0; i < message_data.len; i++){
-        u8 b = message_data.data[i];
+    // save message to channel
+    Channel* ch = Server_tryGetChannel(conn->server, req.channel_id);
+    if(ch == NULL){
+        try_void(sendErrorMessage(log_ctx, conn, res_head,
+            LogSeverity_Warn,
+            STR("invalid channel id")
+        ));
+        Return RESULT_VOID;
     }
-    
+    MessageMeta message_meta;
+    try_void(Channel_saveMessage(ch, message_data, conn->user_id, &message_meta));
 
     // send response
-    // SendMessageResponse res;
-    // SendMessageResponse_construct(&res, res_head, );
-    // try_void(EncryptedSocketTCP_sendStruct(&conn->sock, res_head));
-    // try_void(EncryptedSocketTCP_sendStruct(&conn->sock, &res));
+    SendMessageResponse res;
+    SendMessageResponse_construct(&res, res_head, 
+        message_meta.id, message_meta.receiving_time_utc);
+    try_void(EncryptedSocketTCP_sendStruct(&conn->sock, res_head));
+    try_void(EncryptedSocketTCP_sendStruct(&conn->sock, &res));
 
     Return RESULT_VOID;
 }
diff --git a/src/server/responses/ServerPublicInfo.c b/src/server/responses/ServerPublicInfo.c
index c6bb85e..18eb28e 100644
--- a/src/server/responses/ServerPublicInfo.c
+++ b/src/server/responses/ServerPublicInfo.c
@@ -1,7 +1,8 @@
 #include "responses.h"
 
-#define LOGGER conn->server->logger
-#define LOG_FUNC conn->server->log_func
+#define srv conn->server
+#define LOGGER srv->logger
+#define LOG_FUNC srv->log_func
 #define LOG_CONTEXT log_ctx
 
 declare_RequestHandler(ServerPublicInfo)
@@ -25,10 +26,10 @@ declare_RequestHandler(ServerPublicInfo)
             Return RESULT_VOID;
         }
         case ServerPublicInfo_Name:
-            content = str_castTo_Array_u8(conn->server->name);
+            content = str_castTo_Array_u8(srv->name);
             break;
         case ServerPublicInfo_Description:
-            content = str_castTo_Array_u8(conn->server->description);
+            content = str_castTo_Array_u8(srv->description);
             break;
     }
 
diff --git a/src/server/responses/responses.h b/src/server/responses/responses.h
index e400760..e27c2f9 100644
--- a/src/server/responses/responses.h
+++ b/src/server/responses/responses.h
@@ -17,8 +17,7 @@ Result(void) sendErrorMessage_f(
 
 
 #define declare_RequestHandler(TYPE) \
-    Result(void) handleRequest_##TYPE(\
-        cstr log_ctx, cstr req_type_name, \
+    Result(void) handleRequest_##TYPE(cstr log_ctx, cstr req_type_name, \
         ClientConnection* conn, PacketHeader* req_head, PacketHeader* res_head)
 
 #define case_handleRequest(TYPE) \
@@ -29,5 +28,5 @@ Result(void) sendErrorMessage_f(
 declare_RequestHandler(ServerPublicInfo);
 declare_RequestHandler(Login);
 declare_RequestHandler(Register);
-
-
+declare_RequestHandler(SendMessage);
+declare_RequestHandler(GetMessageBlock);
diff --git a/src/server/responses/send_error.c b/src/server/responses/send_error.c
index ad337d0..0866ba4 100644
--- a/src/server/responses/send_error.c
+++ b/src/server/responses/send_error.c
@@ -1,7 +1,8 @@
 #include "responses.h"
 
-#define LOGGER conn->server->logger
-#define LOG_FUNC conn->server->log_func
+#define srv conn->server
+#define LOGGER srv->logger
+#define LOG_FUNC srv->log_func
 #define LOG_CONTEXT log_ctx
 
 Result(void) sendErrorMessage(
diff --git a/src/server/responses/template b/src/server/responses/template
index d8a5837..d6a9798 100644
--- a/src/server/responses/template
+++ b/src/server/responses/template
@@ -1,7 +1,8 @@
 #include "responses.h"
 
-#define LOGGER conn->server->logger
-#define LOG_FUNC conn->server->log_func
+#define srv conn->server
+#define LOGGER srv->logger
+#define LOG_FUNC srv->log_func
 #define LOG_CONTEXT log_ctx
 
 declare_RequestHandler(NAME)
diff --git a/src/server/server.c b/src/server/server.c
index 7a84377..c74526a 100644
--- a/src/server/server.c
+++ b/src/server/server.c
@@ -2,6 +2,7 @@
 #include "tlibc/filesystem.h"
 #include "tlibc/time.h"
 #include "tlibc/base64.h"
+#include "tlibc/algorithms.h"
 #include "server/server_internal.h"
 #include "network/tcp-chat-protocol/v1.h"
 #include "server/responses/responses.h"
@@ -21,12 +22,15 @@ void Server_free(Server* self){
 
     idb_close(self->db);
 
-    List_UserInfo_destroy(&self->users.cache_list);
-    HashMap_destroy(&self->users.username_id_map);
+    List_UserInfo_destroy(&self->users.list);
+    HashMap_destroy(&self->users.name_id_map);
+
+    for(u32 i = 0; i < self->channels.list.len; i++){
+        Channel_free(self->channels.list.data[i]);
+    }
+    List_ChannelPtr_destroy(&self->channels.list);
+    HashMap_destroy(&self->channels.name_id_map);
 
-    List_MessageBlockMeta_destroy(&self->messages.blocks_meta_list);
-    LList_MessageBlock_destroy(&self->messages.blocks_queue);
-    free(self->messages.incomplete_block);
 
     free(self);
 }
@@ -38,12 +42,12 @@ void Server_free(Server* self){
 
 Result(Server*) Server_create(str config_file_content, cstr config_file_name, 
     void* logger, LogFunction_t log_func)
-    {
+{
     Deferral(16);
     cstr log_ctx = "ServerInit";
     
     Server* self = (Server*)malloc(sizeof(Server));
-    memset(self, 0, sizeof(Server));
+    zeroStruct(self);
     bool success = false;
     Defer(if(!success) Server_free(self));
     
@@ -51,102 +55,110 @@ Result(Server*) Server_create(str config_file_content, cstr config_file_name,
     self->log_func = log_func;
     
     logDebug("parsing config");
-    try(TomlTable* config_toml, p, toml_load_str_filename(config_file_content, config_file_name));
-    Defer(TomlTable_free(config_toml));
+    try(TomlTable* config_top, p, toml_load_str_filename(config_file_content, config_file_name));
+    Defer(TomlTable_free(config_top));
 
+    try(TomlTable* config_server, p, TomlTable_get_table(config_top, STR("server")))
     // parse name
-    try(str* v_name, p, TomlTable_get_str(config_toml, STR("name")));
+    try(str* v_name, p, TomlTable_get_str(config_server, STR("name")));
     self->name = str_copy(*v_name);
 
     // parse description
-    try(str* v_desc, p, TomlTable_get_str(config_toml, STR("description")));
+    try(str* v_desc, p, TomlTable_get_str(config_server, STR("description")));
     self->description = str_copy(*v_desc);
-    
-    // parse landing_channel_id
-    try(i64 v_landing_channel_id, i, TomlTable_get_integer(config_toml, STR("landing_channel_id")));
-    self->landing_channel_id = v_landing_channel_id;
 
     // parse local_address
-    try(str* v_local_address, p, TomlTable_get_str(config_toml, STR("local_address")));
+    try(str* v_local_address, p, TomlTable_get_str(config_server, STR("local_address")));
     try_assert(v_local_address->isZeroTerminated);
     try_void(EndpointIPv4_parse(v_local_address->data, &self->local_end));
+    
+    // parse landing_channel_id
+    try(i64 v_landing_channel_id, i, TomlTable_get_integer(config_server, STR("landing_channel_id")));
+    self->landing_channel_id = v_landing_channel_id;
 
+    try(TomlTable* config_keys, p, TomlTable_get_table(config_top, STR("keys")))
     // parse rsa_private_key
-    try(str* v_rsa_sk, p, TomlTable_get_str(config_toml, STR("rsa_private_key")));
+    try(str* v_rsa_sk, p, TomlTable_get_str(config_keys, STR("rsa_private_key")));
     try_assert(v_rsa_sk->isZeroTerminated);
     try_void(RSA_parsePrivateKey_base64(v_rsa_sk->data, &self->rsa_sk));
 
     // parse rsa_public_key
-    try(str* v_rsa_pk, p, TomlTable_get_str(config_toml, STR("rsa_public_key")));
+    try(str* v_rsa_pk, p, TomlTable_get_str(config_keys, STR("rsa_public_key")));
     try_assert(v_rsa_pk->isZeroTerminated);
     try_void(RSA_parsePublicKey_base64(v_rsa_pk->data, &self->rsa_pk));
     
+    try(TomlTable* config_db, p, TomlTable_get_table(config_top, STR("database")))
     // parse db_aes_key
-    try(str* v_db_aes_key, p, TomlTable_get_str(config_toml, STR("db_aes_key")));
+    try(str* v_db_aes_key, p, TomlTable_get_str(config_db, STR("aes_key")));
     str db_aes_key_s = *v_db_aes_key;
     Array(u8) db_aes_key = Array_u8_alloc(base64_decodedSize(db_aes_key_s.data, db_aes_key_s.len));
     Defer(free(db_aes_key.data));
     base64_decode(db_aes_key_s.data, db_aes_key_s.len, db_aes_key.data);
 
-    // parse db_dir and open db
-    try(str* v_db_dir, p, TomlTable_get_str(config_toml, STR("db_dir")));
+    // parse db_dir
+    try(str* v_db_dir, p, TomlTable_get_str(config_db, STR("dir")));
+
+    // open DB
     try(self->db, p, idb_open(*v_db_dir, db_aes_key));
 
     // build users cache
-    logDebug("loading users...");
+    logInfo("loading users...");
     try(self->users.table, p, 
-        idb_getOrCreateTable(self->db, STR("users"), sizeof(UserInfo), false)
+        idb_getOrCreateTable(self->db, str_null, STR("users"), sizeof(UserInfo), false)
     );
 
     // load whole users table to list
     try_void(
-        idb_createListFromTable(self->users.table, (void*)&self->users.cache_list, false)
+        idb_createListFromTable(self->users.table, (void*)&self->users.list, false)
     );
 
     // build name-id map
     try(u64 users_count, u, idb_getRowCount(self->users.table, false));
-    HashMap_construct(&self->users.username_id_map, u64, NULL);
+    HashMap_construct(&self->users.name_id_map, u64, NULL);
     for(u64 id = 0; id < users_count; id++){
-        UserInfo* user = self->users.cache_list.data + id;
+        UserInfo* user = self->users.list.data + id;
         str key = str_construct(user->name, user->name_len, true);
-        if(!HashMap_tryPush(&self->users.username_id_map, key, &id)){
-            Return RESULT_ERROR_FMT("duplicate user name '"FMT_str"'", key.len, key.data);
+        if(!HashMap_tryPush(&self->users.name_id_map, key, &id)){
+            Return RESULT_ERROR_FMT("duplicate user name '"FMT_str"'", str_expand(key));
         }
     }
-    logDebug("loaded "FMT_u64" users", users_count);
+    logInfo("loaded "FMT_u64" users", users_count);
 
+    // parse channels
+    logDebug("loading channels...");
+    HashMap_construct(&self->channels.name_id_map, u64, NULL);
+    self->channels.list = List_ChannelPtr_alloc(32);
+    try(TomlTable* config_channels, p, TomlTable_get_table(config_top, STR("channels")));
+    
+    HashMapIter channels_iter = HashMapIter_create(config_channels);
+    while(HashMapIter_moveNext(&channels_iter)){
+        HashMapKeyValue kv;
+        HashMapIter_getCurrent(&channels_iter, &kv);
+        str name = kv.key;
+        TomlValue* val = kv.value_ptr;
+        // skip if not table
+        if(val->type != TLIBTOML_TABLE)
+            continue;
+        
+        logInfo("loading channel '"FMT_str"'", str_expand(name))
+        TomlTable* config_channel = val->table;
+        try(u64 id, u, TomlTable_get_integer(config_channel, STR("id")));
+        try(str* v_ch_desc, p, TomlTable_get_str(config_channel, STR("description")))
+        str description = *v_ch_desc;
 
-    // build messages cache
-    logDebug("loading messages...");
-    try(self->messages.blocks_table, p, 
-        idb_getOrCreateTable(self->db, STR("message_blocks"), sizeof(MessageBlock), false)
-    );
-    try(self->messages.blocks_meta_table, p, 
-        idb_getOrCreateTable(self->db, STR("message_blocks_meta"), sizeof(MessageBlockMeta), false)
-    );
+        if(!HashMap_tryPush(&self->channels.name_id_map, name, &id)){
+            Return RESULT_ERROR_FMT("duplicate channel '"FMT_str"'", str_expand(name));
+        }
 
-    // load whole message_blocks_meta table to list
-    try_void(
-        idb_createListFromTable(self->messages.blocks_meta_table, (void*)&self->messages.blocks_meta_list, false)
-    );
-
-    // load N last blocks to the queue
-    self->messages.incomplete_block = LLNode_MessageBlock_createZero();
-    self->messages.blocks_queue = LList_construct(MessageBlock, NULL);
-    try(u64 message_blocks_count, u, idb_getRowCount(self->messages.blocks_table, false));
-    u64 first_id = 0;
-    if(message_blocks_count > MESSAGE_BLOCKS_CACHE_COUNT)
-        first_id = message_blocks_count - MESSAGE_BLOCKS_CACHE_COUNT;
-    for(u64 id = first_id; id < message_blocks_count; id++){
-        LLNode(MessageBlock)* node = LLNode_MessageBlock_createZero();
-        LList_MessageBlock_insertAfter(
-            &self->messages.blocks_queue,
-            self->messages.blocks_queue.last,
-            node
-        );
-        try_void(idb_getRow(self->messages.blocks_table, id, node->value.data, false));
+        logDebug("loading messages...");
+        try(Channel* channel, p, Channel_create(id, name, description, self->db, false));
+        logDebug("loaded "FMT_u64" messages", channel->messages.count);
+        List_ChannelPtr_push(&self->channels.list, channel);
     }
-    logDebug("loaded "FMT_u64" message blocks", message_blocks_count);
+    logDebug("loaded "FMT_u32" channels", self->channels.list.len);
+    // sort channels list by id
+    for(u32 i = 0; i < self->channels.list.len; i++);
+    insertionSort_inline(self->channels.list.data, self->channels.list.len, ->id);
 
     success = true;
     Return RESULT_VALUE(p, self);
@@ -189,6 +201,15 @@ Result(void) Server_run(Server* server){
     Return RESULT_VOID;
 }
 
+Channel* Server_tryGetChannel(Server* self, u64 id){
+    i32 index;
+    binarySearch_inline(self->channels.list.data, self->channels.list.len, id, ->id, index);
+    if(index == -1){
+        return NULL;
+    }
+    Channel* channel = self->channels.list.data[index];
+    return channel;
+}
 
 static void* handleConnection(void* _args){
     ConnectionHandlerArgs* args = (ConnectionHandlerArgs*)_args;
@@ -244,7 +265,10 @@ static Result(void) try_handleConnection(ConnectionHandlerArgs* args, cstr log_c
             case_handleRequest(ServerPublicInfo);
             case_handleRequest(Login);
             case_handleRequest(Register);
+
             // authorized requests
+            case_handleRequest(SendMessage);
+            case_handleRequest(GetMessageBlock);
         }
     }
 
diff --git a/src/server/server_internal.h b/src/server/server_internal.h
index d260ca1..8709182 100644
--- a/src/server/server_internal.h
+++ b/src/server/server_internal.h
@@ -17,6 +17,40 @@ LList_declare(MessageBlock);
 
 #define MESSAGE_BLOCKS_CACHE_COUNT 50
 
+typedef struct Channel {
+    u64 id;
+    str name;
+    str description;
+    struct {
+        u64 count;
+        Table* blocks_table;
+        Table* blocks_meta_table;
+        List(MessageBlockMeta) blocks_meta_list; // index is id
+        // last MESSAGE_BLOCKS_CACHE_COUNT MessageBlocks, ascending
+        // new messages are written to the last block
+        LList(MessageBlock) blocks_queue;
+    } messages;
+} Channel;
+
+typedef Channel* ChannelPtr;
+List_declare(ChannelPtr);
+
+Result(Channel*) Channel_create(u64 id, str name, str description,
+    IncrementalDB* db, bool lock_db);
+
+void Channel_free(Channel* self);
+
+Result(void) Channel_saveMessage(Channel* self, Array(u8) message_data, u64 sender_id,
+    MessageMeta* out_message_meta);
+
+/// @param out_data buffer of size >= MESSAGE_SIZE_MAX
+Result(void) Channel_loadMessage(Channel* self, u64 id, 
+    MessageMeta* out_meta, u8* out_data);
+
+Result(void) Channel_loadMessageBlock(Channel* self, u64 fisrt_message_id, u32 count,
+    MessageBlockMeta* out_meta, MessageBlock* out_block);
+
+
 typedef struct Server {
     /* from constructor */
     void* logger;
@@ -34,19 +68,17 @@ typedef struct Server {
     IncrementalDB* db;
     struct {
         Table* table;
-        List(UserInfo) cache_list; // index is id
-        HashMap(u64) username_id_map;
+        List(UserInfo) list; // index is id
+        HashMap(u64) name_id_map;
     } users;
-    /* messages */
     struct {
-        Table* blocks_table;
-        Table* blocks_meta_table;
-        List(MessageBlockMeta) blocks_meta_list; // index is id
-        LList(MessageBlock) blocks_queue; // last N MessageBlocks, ascending
-        LLNode(MessageBlock)* incomplete_block; // new messages are written here until block is full
-    } messages;
+        List(ChannelPtr) list;
+        HashMap(u64) name_id_map;
+    } channels;
 } Server;
 
+Channel* Server_tryGetChannel(Server* self, u64 id);
+
 
 typedef struct ClientConnection {
     Server* server;
@@ -55,6 +87,7 @@ typedef struct ClientConnection {
     Array(u8) session_key;
     EncryptedSocketTCP sock;
     bool authorized;
+    u64 user_id; // -1 for unauthorized
 } ClientConnection;
 
 typedef struct ConnectionHandlerArgs {
diff --git a/tcp-chat-server.toml.default b/tcp-chat-server.toml.default
index d9a6ea1..0349bb3 100644
--- a/tcp-chat-server.toml.default
+++ b/tcp-chat-server.toml.default
@@ -1,13 +1,21 @@
+[server]
 name = "Test Server"
 description = """\
     Lorem ipsum labuba aboba.\n\
     Qqqqq...\
     """
-
-landing_channel_id = 0
 local_address = '127.0.0.1:9988'
-db_dir = 'server-db'
-db_aes_key = '<generate with './tcp-chat --random-bytes-base64 32'>'
+landing_channel_id = 0
 
+# do not create channels with the same id
+[channels.general]
+id = 0
+description = "a text channel"
+
+[database]
+dir = 'server-db'
+aes_key = '<generate with './tcp-chat --random-bytes-base64 32'>'
+
+[keys]
 rsa_private_key = '<generate with './tcp-chat --rsa-gen-random'>'
 rsa_public_key = '<copy from output of command above>'