Winsock send function waits indefinitely

Question

In this code, send function doesn't block but doesn't send either. If I call shutdown , then it is forced to send.

How do I make this code send a small message within a second or so?

This code is suppose to respond to web browser GET request. (User types localhost:27015) It is just a test, I do not need it for work or a bigger project.

#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif

#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <iphlpapi.h>
#include <stdio.h>

#pragma comment(lib, "Ws2_32.lib")


int main(int argc, wchar_t* argv[]) {

WSADATA wsaData;
int iResult = 0;

SOCKET ListenSocket = INVALID_SOCKET;
sockaddr_in service;

iResult = WSAStartup(MAKEWORD(2, 2), &wsaData); 

ListenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

service.sin_family = AF_INET;
service.sin_addr.s_addr = inet_addr("127.0.0.1");
service.sin_port = htons(27015);

iResult = bind(ListenSocket, (SOCKADDR *)& service, sizeof(service));

listen(ListenSocket, SOMAXCONN);

auto AcceptSocket = accept(ListenSocket, NULL, NULL);

char getbuf[400];

recv(AcceptSocket, getbuf, 400, NULL);
getbuf[399] = '\0';

printf("%s",getbuf);

char str[] = "HTTP/1.1 200 OK\r\n"
"Date: Sun, 19 May 2018 08 : 56 : 53 GMT\r\n"
"Server : Apache / 2.2.14 (Win32)\r\n"
"Last - Modified : Sat, 20 Nov 2004 07 : 16 : 26 GMT\r\n"
"ETag : \"10000000565a5-2c-3e94b66c2e680\" \r\n"
"Accept - Ranges : bytes\r\n"
"Content - Length : 44\r\n"
"Connection : close\r\n"
"Content - Type : text / html\r\n"
"X - Pad : avoid browser bug\r\n\r\n"

"<html><body><h1>It works!</h1> </body> </html>\r\n\0";


char *sendbuf = (char*)str;
iResult = send(AcceptSocket, sendbuf, (int)strlen(str), 0);

//shutdown(AcceptSocket, SD_BOTH); //forces to send

while (1);
return 0;
}

Also all the headers are wrong, and the Content-length is 48 not 44, and you should care about what recv() returns. — Havenard
But it is after the send function. Firefox is waiting unless I uncomment shutdown function. — user3761570
With HTTP 1.1 or higher, the browser uses the same TCP session to perform multiple requests. After it is done receiving the data it asked for, it will make more requests during the same connection. If your application is not prepared to handle that, the browser might hang. Since you are obviously experimenting HTTP for the first time, I recommend you use HTTP 1.0, and just terminate the connection after sending data. Also, in that model, specifying Content-Length is optional. — Havenard
At this stage I only care to make the send function send without shutdown function — user3761570

Havenard Havenard · Accepted Answer · 2018-05-20T20:34:28

char str[] = 
"HTTP/1.1 200 OK\r\n"
"Date: Sun, 19 May 2018 08:56:53 GMT\r\n"
"Server: Apache/2.2.14 (Win32)\r\n"
"Last-Modified: Sat, 20 Nov 2004 07:16:26 GMT\r\n"
"ETag: \"10000000565a5-2c-3e94b66c2e680\"\r\n"
"Accept-Ranges: bytes\r\n"
"Content-Length: 46\r\n"
"Connection: close\r\n"
"Content-Type: text/html\r\n"
"X-Pad: avoid browser bug\r\n\r\n"
"<html><body><h1>It works!</h1></body></html>\r\n";

The browser isn't a person, it doesn't know what the hell is Content - Type :, it doesn't recognize 08 : 56 : 53 as a valid time, there is no MIME type called text / html. Stop putting spaces where there shouldn't be any, the browser doesn't have a brain, it can't guess.

Also you are explicitly telling the connection will close after the data is sent, with the header Connection: close, but you are not doing that. If you intent to keep the connection alive, then use Connection: keep-alive.

Moreover, your data is not 44 bytes in length.

Winsock send function waits indefinitely

1 Answers