recv | 易学教程

python socket基础

阅读更多关于 python socket基础

# socket """ Socket又称"套接字"，应用程序通常通过"套接字"向网络发出请求或者应答网络请求，使主机间或者一台计算机上的进程间可以通讯语法： socket.socket(AddressFamily, Type) 该函数带有两个参数： Address Family：可以选择 AF_INET（用于 Internet 进程间通信）或者 AF_UNIX（用于同一台机器进程间通信）,实际工作中常用AF_INET Type：套接字类型，可以是 SOCK_STREAM（流式套接字，主要用于 TCP 协议）或者 SOCK_DGRAM（数据报套接字，主要用于 UDP 协议）套接字使用流程: 创建套接字使用套接字收/发数据关闭套接字 """ # 创建TCP 语法 """ import socket # 创建tcp的套接字 tcp_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # ...这里是使用套接字的功能... # 关闭套接字 tcp_socket.close() """ # 创建UDP 语法 """ import socket # 创建tcp的套接字 tcp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # ..

Why server waits for a client after the client application has been put in STOPPED state?

阅读更多关于 Why server waits for a client after the client application has been put in STOPPED state?

问题 This question is an extension to this previously asked question: I implemented the solution given by jxh with following params: SO_KEEPALIVE = Enabled TCP_KEEPIDLE = 120 secs TCP_KEEPINTVL = 75 secs TCP_KEEPCNT = 1 Then why the server still waits forever for client to respond? Also I found out on internet that kill <pid> actually sends SIGTERM to the given process. So I used ps -o pid,cmd,state command after 'killing' the telnet application. I saw that the telnet process was still there but

Unexpected results with select and recvfrom

阅读更多关于 Unexpected results with select and recvfrom

问题 fd_set rset; struct timeval tv; FD_ZERO(&rset); FD_SET(sockfd, &rset); tv.tv_sec = 1; tv.tv_usec = 0; for(;;) { for(count = 0; count < elements in sockaddr_in array; count++) { //flag_array is filled with -1 before for(;;) if(flag_array[count] == -1 && select(sockfd+1, &rset, NULL, NULL, &tv)) { recvfrom(...) } tv.tv_sec = 1; FD_ZERO(&rset);//this fixed it FD_SET(sockfd, &rset);//and this too } //contact everyone from sockaddr array (works like a charm!) } If I don't send my message from my

How to check if all data are received with a TCP Socket in Python

阅读更多关于 How to check if all data are received with a TCP Socket in Python

问题 I am trying to get data from a TCP Connection (client side only) using Python as programming language, However, I could see that all data are not received in once and are cut in the middle of the receiving process ... I could see on forums that TCP does not send data in the correct order (it is a bit random, link: Python socket receive - incoming packets always have a different size), am I wrong ? My question is if there is anyway to make sure that I correctly received all data? Thanks in

Winsock2 - how to open a TCP socket that allows recv() with MSG_WAITALL?

阅读更多关于 Winsock2 - how to open a TCP socket that allows recv() with MSG_WAITALL?

问题 In this code: // error checking is omitted // init Winsock2 WSADATA wsaData; WSAStartup(MAKEWORD(2, 2), &wsaData); // connect to server struct addrinfo *res = NULL, *ptr = NULL, hints; ZeroMemory(&hints, sizeof(hints)); hints.ai_family = AF_INET; hints.ai_socktype = SOCK_STREAM; hints.ai_protocol = IPPROTO_TCP; getaddrinfo(server_ip, "9999", &hints, &res); SOCKET client_socket = socket(res->ai_family, res->ai_socktype, res->ai_protocol); connect(client_socket, res->ai_addr, (int)res->ai

Unusual select / sock stream behavior behavior

阅读更多关于 Unusual select / sock stream behavior behavior

问题 I'm writing a small program to request a chunk of a file, and then have another program return that specific chunk of the file. I can get this to work using files up to about 555000 bytes, but on anything lager than that, I get unusual behavior. In my loop, I check a progress buffer, which is an array of integers, to see whether or not I have a specific chunk of the file. If I do, then I don't send a request for that chunk, but if I don't, then I request the chunk from a peer. I have a linked

Getting number of bytes available to read in a socket

阅读更多关于 Getting number of bytes available to read in a socket

问题 Here's my scenario. I have a TCP client that is talking to the server. Both the server and the client are running on local machine (Windows). The dialog goes something like: Client sends data to the server (Request) Client does shutdown for send on the socket Client blocks via a read call for response Server receives the data, processes, and sends back a response (one shot, not broken into chunks) Server does shutdown for send on the socket Client receives the response, and continues

c++ Socket select and receive problem

阅读更多关于 c++ Socket select and receive problem

问题 Below is the code fragment I have issue with socket programing. Here after select call, If I do not put a sleep on line 9, on Windows XP, 1 byte is received on line 11 (instead 4 byte is sent from server as integer), when I check xmlSize, it is set to 0. Because iResult is 1, execution continues and on line 15 second receive is called with xmlSize=0, and iResult is set to 0 and afterwards because iResult=0 connection is closed. But on Windows 7 this did not happen, program happily read 4

socket缓冲区

阅读更多关于 socket缓冲区

【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 1, 概述每个 socket 被创建后，都会分配两个缓冲区，输入缓冲区和输出缓冲区。 write()/send() 并不立即向网络中传输数据，而是先将数据写入缓冲区中，再由TCP协议将数据从缓冲区发送到目标机器。一旦将数据写入到缓冲区，函数就可以成功返回，不管它们有没有到达目标机器，也不管它们何时被发送到网络，这些都是 TCP协议负责的事情。 TCP协议独立于 write()/send() 函数，数据有可能刚被写入缓冲区就发送到网络，也可能在缓冲区中不断积压，多次写入的数据被一次性发送到网络，这取决于当时的网络情况、当前线程是否空闲等诸多因素，不由程序员控制。 read()/recv() 函数也是如此，也从输入缓冲区中读取数据，而不是直接从网络中读取。这些I/O缓冲区特性可整理如下： I/O缓冲区在每个TCP套接字中单独存在； I/O缓冲区在创建套接字时自动生成；即使关闭套接字也会继续传送输出缓冲区中遗留的数据；关闭套接字将丢失输入缓冲区中的数据。输入输出缓冲区的默认大小一般都是 8K，可以通过 getsockopt() 函数获取： unsigned optVal; int optLen = sizeof(int); getsockopt(servSock, SOL_SOCKET,

return value of recv() function in perl

阅读更多关于 return value of recv() function in perl

问题 I have non blocking UDP socket in perl created this way my $my_sock = IO::Socket::INET->new(LocalPort => $MY_PORT, Proto => 'udp', Blocking => '0') or die "socket: $@"; The recv call is my $retValue = $sock->recv($my_message, 64); I need to know a) when there is no data left to read b) if there is data, how much data was read c) any error conditions Surprisingly, I didn't see any return value for recv in perldoc. When I tried it myself, recv returns undef in (a), for b it is an unprintable