tcp

Java: properly closing sockets for multi threaded servers

由 為{幸葍}努か 提交于 2021-02-16 18:06:33
问题 I'm trying to create a multi threaded server to which multiple clients can connect and can be served. However, I'm not sure on how to properly free up my resources should the need arise. My server runs an input thread (waiting for user inputs) and a procressing thread (handles connections and users). I open up a ServerSocket in the server class and pass it to my processing thread. It looks like this: public class ClientConnector implements Runnable { private ServerSocket serverSocket; public

图解TCP-IP协议

由 强颜欢笑 提交于 2021-02-11 21:55:13
本文通过两个图来梳理TCP-IP协议相关知识。TCP通信过程包括三个步骤：建立TCP连接通道，传输数据，断开TCP连接通道。如图1所示，给出了TCP通信过程的示意图。 图1 TCP 三次握手四次挥手 图1主要包括三部分：建立连接、传输数据、断开连接。 1)建立TCP连接很简单，通过三次握手便可建立连接。 2)建立好连接后，开始传输数据。TCP数据传输牵涉到的概念很多：超时重传、快速重传、流量控制、拥塞控制等等。 3)断开连接的过程也很简单，通过四次握手完成断开连接的过程。 三次握手建立连接： 第一次握手：客户端发送syn包(seq=x)到服务器，并进入SYN_SEND状态，等待服务器确认； 第二次握手：服务器收到syn包，必须确认客户的SYN（ack=x+1），同时自己也发送一个SYN包（seq=y），即SYN+ACK包，此时服务器进入SYN_RECV状态； 第三次握手：客户端收到服务器的SYN＋ACK包，向服务器发送确认包ACK(ack=y+1)，此包发送完毕，客户端和服务器进入ESTABLISHED状态，完成三次握手。 握手过程中传送的包里不包含数据，三次握手完毕后，客户端与服务器才正式开始传送数据。理想状态下，TCP连接一旦建立，在通信双方中的任何一方主动关闭连接之前，TCP 连接都将被一直保持下去。 传输数据过程： a. 超时重传 超时重传机制用来保证TCP传输的可靠性

How to connect to PC (server) using sockets with Android app (client)?

由 假装没事ソ 提交于 2021-02-11 14:27:56
问题 I have a server set up on my PC (using Hercules), which is listening on a port # and waiting for a connection. I can't get the android app to receive messages from the server however on my android emulator (Strangely I can send messages to the server), and I can't do either from my physical android phone. All the examples I'm finding online involve android devices connecting to each other, like this one: https://www.coderzheaven.com/2017/05/01/client-server-programming-in-android-send-message

Python socket: trying to receive a new TCP message within a while loop

由 依然范特西╮ 提交于 2021-02-11 14:24:12
问题 Hope everyone's doing well. I have a problem I've been trying to solve for a good while now with no success... I have this function that listens for commands sent by pressing various buttons on a website. Once it receives a command it sends it further down the serial port: def write(self): while self.alive: try: data = self.socket.recv(1024) print('Data received through TCP: ' + str(data)) recvdStr = data.decode('UTF-8') if not data: break self.serial.write(recvdString.encode('utf-8')) print(

DOES router or linux kernel change the tcp headers and ip headers of packets

由 守給你的承諾、 提交于 2021-02-11 14:21:37
问题 I was looking into raw sockets. so I created one raw socket client and other one is server. on two different computers. I am using ISP provided router. so I sent spoofed packet (with iphdr struct's saddr of different computer on same network) from client but when the packet received at the server the source ip in packet's ip header was correct (the real sender address=client address) plus the source port and destination port of tcphdr were something different too (which really didnt make

DOES router or linux kernel change the tcp headers and ip headers of packets

由 ◇◆丶佛笑我妖孽 提交于 2021-02-11 14:20:37
问题 I was looking into raw sockets. so I created one raw socket client and other one is server. on two different computers. I am using ISP provided router. so I sent spoofed packet (with iphdr struct's saddr of different computer on same network) from client but when the packet received at the server the source ip in packet's ip header was correct (the real sender address=client address) plus the source port and destination port of tcphdr were something different too (which really didnt make

How to create a working TCP Server socket in spring boot and how to handle the incoming message?

由 佐手、 提交于 2021-02-11 14:14:24
问题 I have tried to implement a TCP server socket with spring integration in an allready existing spring boot application, but I am facing a problem and this problem drives me crazy... The client is sending a message (a byte array) to the server and timesout. That's it. I am not receiving any exceptions from the server. It seems I have provided the wrong port or somthing but after checking the port, I am sure it is the right one. This is my annotation based configuration class: import home.brew

How to pass objects from one thread class to another thread class in python

由 天涯浪子 提交于 2021-02-11 13:59:45
问题 I am using socket module in python to create two clients and one server. Client_1 shall send content of a .txt file to Client_2, through the server. In server I am using thread module to have a multiple client support. I have created three Threads in my server:- 1) First thread handles the client connections 2) Second thread receives the contents of the .txt file from Client_1 3) Third thread sends this contents to Client_2 The problem that I am facing, while executing the above mentioned

Boost receive data from the tcp socket

由 折月煮酒 提交于 2021-02-11 01:16:36
问题 I am trying to read specific number of bytes from the socket. My server is sending: 1) byte[0] - length of the message 2) byte[1:N] - the actual message How do I read the first byte and then read the remaining bytes using boost::asio::ip::tcp::socket::read ? Here is the code snippet: // receive data through the socket void TCPTestClient::ReceiveData( ) { try { boost::system::error_code error; boost::asio::streambuf receivedStreamBuffer; // reserve 512 bytes in output sequence boost::asio:

Boost receive data from the tcp socket

由 我是研究僧i 提交于 2021-02-11 01:13:11
问题 I am trying to read specific number of bytes from the socket. My server is sending: 1) byte[0] - length of the message 2) byte[1:N] - the actual message How do I read the first byte and then read the remaining bytes using boost::asio::ip::tcp::socket::read ? Here is the code snippet: // receive data through the socket void TCPTestClient::ReceiveData( ) { try { boost::system::error_code error; boost::asio::streambuf receivedStreamBuffer; // reserve 512 bytes in output sequence boost::asio:
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