diff --git a/src/bin/transistor-client.rs b/src/bin/transistor-client.rs
index 8c0c8f0..b6eeb0a 100644
--- a/src/bin/transistor-client.rs
+++ b/src/bin/transistor-client.rs
@@ -17,11 +17,9 @@ fn main() -> Result<(), Error> {
     let server = &args[1];
 
     println!("[INF] transistor client startup! server: {}", server);
-
     print_displays();
 
     let mut client = Client::new(server)?;
-
     client.start()?;
 
     loop {}
diff --git a/src/client.rs b/src/client.rs
index f0ef9f2..2bc1215 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -1,7 +1,8 @@
 use std::collections::HashMap;
-use std::io::{stdout, Error, ErrorKind::*, Read, Write};
-use std::{fs, net::TcpStream};
-use std::{mem, u32};
+use std::fs;
+use std::io::{stdout, Error, ErrorKind::*, Write};
+use std::mem;
+use std::net::TcpStream;
 
 use bincode::deserialize;
 use display_info::DisplayInfo;
@@ -45,33 +46,64 @@ impl Client {
 
     pub fn start(&mut self) -> Result<(), Error> {
         // transmit cid to server
-        tcp_stream_write!(self.tcp, self.cid);
+        if let Err(e) = tcp_write(&mut self.tcp, self.cid) {
+            return Err(Error::new(
+                ConnectionRefused,
+                format!("handshake failed: {:?}", e),
+            ));
+        };
 
         /* receive display counts; 0 is unauthorized */
         let mut buffer = vec![0u8; mem::size_of::<u32>()];
-        tcp_stream_read!(self.tcp, buffer);
+
+        if let Err(e) = tcp_read(&mut self.tcp, &mut buffer) {
+            return Err(Error::new(
+                ConnectionRefused,
+                format!("handshake failed: {:?}", e),
+            ));
+        };
+
         let disp_cnt: u32 = deserialize(&buffer).unwrap();
 
         if disp_cnt < 1 {
-            return Err(Error::new(ConnectionRefused, "[ERR] authorization failed"));
+            return Err(Error::new(ConnectionRefused, "authorization failed"));
         }
 
         // receive server's current display configurations
-        tcp_stream_read_resize!(self.tcp, buffer);
+        if let Err(e) = tcp_read(&mut self.tcp, &mut buffer) {
+            return Err(Error::new(
+                ConnectionRefused,
+                format!("handshake failed: {:?}", e),
+            ));
+        };
+
         let server_disp_map: HashMap<Did, Display> = deserialize(&buffer).unwrap();
         let server_disp: Vec<Display> = server_disp_map.values().cloned().collect();
 
-        // configure our displays' attach position and transmit to server
+        /* configure our displays' attach position and transmit to server */
         self.set_display_position(server_disp);
-        tcp_stream_write!(self.tcp, self.displays);
+
+        if let Err(e) = tcp_write(&mut self.tcp, self.displays.clone()) {
+            return Err(Error::new(
+                ConnectionRefused,
+                format!("handshake failed: {:?}", e),
+            ));
+        };
 
         /* wait server ack */
-        tcp_stream_read!(self.tcp, buffer);
+        if let Err(e) = tcp_read(&mut self.tcp, &mut buffer) {
+            return Err(Error::new(
+                ConnectionRefused,
+                format!("handshake failed: {:?}", e),
+            ));
+        };
 
         if let HandshakeStatus::HandshakeErr = deserialize(&buffer).unwrap() {
             return Err(Error::new(ConnectionRefused, "[ERR] request rejected"));
         };
 
+        println!("[INF] connected!");
+
         Ok(())
     }
 
@@ -132,6 +164,22 @@ impl Client {
     }
 }
 
+fn load_or_generate_cid() -> Result<Cid, Error> {
+    let cid_file = config_dir!("client").join("cid.txt");
+
+    if cid_file.exists() {
+        let txt = fs::read_to_string(cid_file)?;
+        Ok(txt.parse().expect("[ERR] failed to load cid"))
+    } else {
+        let cid: Cid = rand::random();
+
+        let mut file = fs::File::create(&cid_file)?;
+        file.write_all(cid.to_string().as_bytes())?;
+
+        Ok(cid)
+    }
+}
+
 fn prompt_display_position(displays: &mut Vec<Display>, server_conf: Vec<Display>) {
     println!("\n########## display position setup ##########");
     println!("[INF] current server displays:");
@@ -213,20 +261,6 @@ fn prompt_display_position(displays: &mut Vec<Display>, server_conf: Vec<Display
             }
         }
     }
-}
-
-fn load_or_generate_cid() -> Result<Cid, Error> {
-    let cid_file = config_dir!("client").join("cid.txt");
-
-    if cid_file.exists() {
-        let txt = fs::read_to_string(cid_file)?;
-        Ok(txt.parse().expect("[ERR] failed to load cid"))
-    } else {
-        let cid: Cid = rand::random();
 
-        let mut file = fs::File::create(&cid_file)?;
-        file.write_all(cid.to_string().as_bytes())?;
-
-        Ok(cid)
-    }
+    // TODO: ask write config to file
 }
diff --git a/src/display.rs b/src/display.rs
index 874ca0f..f4e7b32 100644
--- a/src/display.rs
+++ b/src/display.rs
@@ -140,7 +140,7 @@ pub fn create_warpzones(a: &mut Vec<Display>, b: &mut Vec<Display>, eq: bool) ->
             if disp.is_overlap(target.clone()) {
                 return Err(Error::new(
                     InvalidInput,
-                    "[ERR] two displays are overlapping",
+                    "displays are overlapping",
                 ));
             }
 
@@ -181,12 +181,14 @@ pub fn create_warpzones_hashmap(
             if disp.is_overlap(target.clone()) {
                 return Err(Error::new(
                     InvalidInput,
-                    "[ERR] two displays are overlapping",
+                    "displays are overlapping",
                 ));
             }
         }
     }
 
+    // ! TODO: verify isolated display before add
+
     // add warpzones
     for disp in a.iter() {
         for target in b.iter() {
diff --git a/src/server.rs b/src/server.rs
index 21701f2..75e5778 100644
--- a/src/server.rs
+++ b/src/server.rs
@@ -1,6 +1,6 @@
 use std::collections::HashMap;
 use std::fs;
-use std::io::{Error, ErrorKind::*, Read, Write};
+use std::io::{Error, ErrorKind::*};
 use std::mem;
 use std::net::TcpListener;
 use std::path::PathBuf;
@@ -86,43 +86,68 @@ fn handle_client(
     mut displays: Arc<RwLock<HashMap<Did, Display>>>,
     disp_ids: Arc<RwLock<AssignedDisplays>>,
     authorized: Vec<Cid>,
-) -> Result<(), Error> {
+) {
     let tcp = TcpListener::bind(("0.0.0.0", PORT)).expect("[ERR] TCP binding failed");
 
     for mut stream in tcp.incoming().filter_map(Result::ok) {
+        let ip = stream.peer_addr().unwrap();
+
         // read cid from remote client
         let mut buffer = vec![0u8; mem::size_of::<Cid>()];
-        tcp_stream_read!(stream, buffer);
+
+        if let Err(e) = tcp_read(&mut stream, &mut buffer) {
+            eprintln!("[ERR] client {:?} handshake failed: {:?}", ip, e);
+            continue;
+        };
+
         let cid = deserialize(&buffer).unwrap();
 
-        // reject not known client
+        // reject unknown client
         if !authorized.contains(&cid) {
-            tcp_stream_write!(stream, 0);
+            if let Err(e) = tcp_write(&mut stream, 0) {
+                eprintln!("[ERR] client {:?} handshake failed: {:?}", ip, e);
+                continue;
+            };
         }
 
         // transmit display counts to client
-        tcp_stream_write!(stream, displays.read().unwrap().len() as u32);
+        if let Err(e) = tcp_write(&mut stream, displays.read().unwrap().len() as u32) {
+            eprintln!("[ERR] client {:?} handshake failed: {:?}", ip, e);
+            continue;
+        };
 
         // transmit current displays
         {
             let disp = displays.read().unwrap();
-            tcp_stream_write!(stream, *disp);
+
+            if let Err(e) = tcp_write(&mut stream, disp.clone()) {
+                eprintln!("[ERR] client {:?} handshake failed: {:?}", ip, e);
+                continue;
+            };
         }
 
         // receive display attach request
-        tcp_stream_read_resize!(stream, buffer);
+        if let Err(e) = tcp_read(&mut stream, &mut buffer) {
+            eprintln!("[ERR] client {:?} handshake failed: {:?}", ip, e);
+            continue;
+        };
+
         let mut client_disp: Vec<Display> = deserialize(&buffer).unwrap();
 
         // update warpzones for new displays
         let new = match create_warpzones_hashmap(&mut displays, &mut client_disp) {
             Ok(new) => new,
-            Err(_) => {
-                return Err(Error::new(InvalidData, "[ERR] system display init failed"));
+            Err(e) => {
+                eprintln!("[ERR] invalid request from client {:?} : {:?}", ip, e);
+                continue;
             }
         };
-         
+
         // transmit ack
-        tcp_stream_write!(stream, HandshakeStatus::HandshakeOk);
+        if let Err(e) = tcp_write(&mut stream, HandshakeStatus::HandshakeOk as i32) {
+            eprintln!("[ERR] client {:?} handshake failed: {:?}", ip, e);
+            continue;
+        };
 
         // add accepted client and display list
         let client = Client {
@@ -133,9 +158,9 @@ fn handle_client(
 
         clients.write().unwrap().insert(cid, client);
         disp_ids.write().unwrap().client.extend(new);
-    }
 
-    Ok(())
+        println!("[INF] client {:?} connected!", ip);
+    }
 }
 
 fn authorized_clients(file: PathBuf) -> Result<Vec<Cid>, Error> {
diff --git a/src/utils.rs b/src/utils.rs
index bb812aa..591219b 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -1,5 +1,5 @@
-use std::io::stdin;
-use std::io::{Error, ErrorKind::*};
+use std::io::{stdin, Error, ErrorKind::*, Read, Write};
+use std::net::TcpStream;
 
 use display_info::DisplayInfo;
 use serde::{Deserialize, Serialize};
@@ -48,6 +48,29 @@ pub fn stdin_char() -> Result<char, Error> {
     }
 }
 
+pub fn tcp_read(stream: &mut TcpStream, buffer: &mut Vec<u8>) -> Result<usize, Error> {
+    let mut size = [0u8; 4];
+    stream.read_exact(&mut size)?;
+
+    let len = u32::from_be_bytes(size) as usize;
+    buffer.resize(len, 0);
+
+    stream.read_exact(buffer)?;
+
+    Ok(len)
+}
+
+pub fn tcp_write<T: Serialize>(stream: &mut TcpStream, data: T) -> Result<usize, Error> {
+    let encoded = bincode::serialize(&data).unwrap();
+    let len = encoded.len();
+    let size = (len as u32).to_be_bytes(); // force 4 byte data length
+
+    stream.write_all(&size)?;
+    stream.write_all(&encoded)?;
+
+    Ok(len)
+}
+
 #[macro_export]
 macro_rules! config_dir {
     ($subpath: expr) => {{
@@ -61,48 +84,3 @@ macro_rules! config_dir {
     }};
 }
 
-#[macro_export]
-macro_rules! tcp_stream_read {
-    ($stream:expr, $buffer:expr) => {{
-        let mut size = [0u8; 4];
-        $stream.read_exact(&mut size)?;
-
-        let len = u32::from_be_bytes(size) as usize;
-        $stream.read_exact(&mut $buffer[..len])?;
-
-        len
-    }};
-}
-
-#[macro_export]
-macro_rules! tcp_stream_read_resize {
-    ($stream:expr, $buffer:expr) => {{
-        let mut size = [0u8; 4];
-        $stream.read_exact(&mut size)?;
-
-        let len = u32::from_be_bytes(size) as usize;
-        $buffer.resize(len, 0);
-        $stream.read_exact(&mut $buffer)?;
-
-        len
-    }};
-}
-
-#[macro_export]
-macro_rules! tcp_stream_write {
-    ($stream:expr, $data:expr) => {
-        let encoded = bincode::serialize(&$data).unwrap();
-
-        // force 4 byte data length
-        let len = encoded.len() as u32;
-        let size = len.to_be_bytes();
-
-        if let Err(e) = $stream.write_all(&size) {
-            eprintln!("[ERR] TCP stream write failed: {}", e);
-        }
-
-        if let Err(e) = $stream.write_all(&encoded) {
-            eprintln!("[ERR] TCP stream write failed: {}", e);
-        }
-    };
-}