Notes

#include "stdafx.h"
#include "CustomerManagerService.h"

#define LHOST NULL
#define LPORT "42424"
#define RECVBUFSIZE 58623

int __cdecl main()
{

WSADATA wsaData = { 0 };
int result = WSAStartup(MAKEWORD(2, 2), &wsaData);
if (result != 0) {
printf("WSAStartup failed: %dn", result);
return -1;
}

struct addrinfo hints = { 0 };
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
hints.ai_flags = AI_PASSIVE;

struct addrinfo *ainfo;
result = getaddrinfo(LHOST, LPORT, &hints, &ainfo);
if (result != 0) {
printf("getaddrinfo failed: %dn", result);
WSACleanup();
return -1;
}

SOCKET listenSocket;
if ((listenSocket = socket(ainfo->ai_family, ainfo->ai_socktype, ainfo->ai_protocol)) == INVALID_SOCKET) {
printf("socket() failed with error: %ldn", WSAGetLastError());
freeaddrinfo(ainfo);
WSACleanup();
return -1;
}

// Setup the TCP listening socket
if ((bind(listenSocket, ainfo->ai_addr, (int)ainfo->ai_addrlen)) == SOCKET_ERROR) {
printf("bind() failed with error: %dn", WSAGetLastError());
freeaddrinfo(ainfo);
closesocket(listenSocket);
WSACleanup();
return -1;
}
freeaddrinfo(ainfo);

// Listen on the socket
if (listen(listenSocket, SOMAXCONN) == SOCKET_ERROR) {
printf("listen() failed with error: %ldn", WSAGetLastError());
closesocket(listenSocket);
WSACleanup();
return -1;
}

printf("-=-=-=-=-=-=- Listening for connections -=-=-=-=-=-=- n");


while (1) {

SOCKET clientSocket;
if ((clientSocket = accept(listenSocket, NULL, NULL)) == INVALID_SOCKET) {
printf("accept failed: %dn", WSAGetLastError());
continue;
}
printf("Connection received from remote host.n");

_beginthread(&handleConnection, 0, (void*)clientSocket);
printf("Connection handed off to handler thread.n");
}
}

void __cdecl handleConnection(void *param) {
SOCKET clientSocket = (SOCKET)param;

char recvbuf[RECVBUFSIZE] = { '' };
size_t recvbufUsed = 0;
const char* msgPleaseSendShorterLines = "Please send shorter lines.";
const char* msgBye = "Bye!";
while (1) {
size_t buf_remain = sizeof(recvbuf) - recvbufUsed;

if (buf_remain < 1) {
printf("[!] recvbuf exhausted. Giving up.n");
send(clientSocket, msgPleaseSendShorterLines, strlen(msgPleaseSendShorterLines), 0);
break;
}

int result = recv(clientSocket, (void*)&recvbuf[recvbufUsed], buf_remain, 0);

if (result == 0) {
printf("Client disconnected.n");
break;
}
else if (result < 0) {
printf("recv() failed: %d.n", WSAGetLastError());
break;
}

printf("Bytes received: %dn", result);

recvbufUsed += result;

char *line_start = recvbuf;
char *line_end;
while ((line_end = (char*)memchr((void*)line_start, 'n', recvbufUsed - (line_start - recvbuf))) != 0)
{

*line_end = '';

if (strcmp(line_start, "exit") == 0) {
printf("Client requested exit.n");
send(clientSocket, msgBye, strlen(msgBye), 0);
closesocket(clientSocket);
return;
}

doResponse(clientSocket, line_start);

line_start = line_end + 1;
}

recvbufUsed -= (line_start - recvbuf);

memmove_s(recvbuf, sizeof(recvbuf), line_start, recvbufUsed);
}
closesocket(clientSocket);
return;
}

int __cdecl doResponse(SOCKET clientSocket, char *clientName) {
char response[128];

sprintf(response, "ERROR %s...n", clientName);

int result = send(clientSocket, response, strlen(response), 0);
if (result == SOCKET_ERROR) {
printf("send failed: %dn", WSAGetLastError());
closesocket(clientSocket);
return -1;
}
printf("Bytes sent: %dn", result);
return 0;