TÉLÉCHARGER UN FICHIER (WIN32, SOCKETS)

#include <stdio.h>
#include <winsock2.h>
#include <windows.h>
#include <commctrl.h>
#include "resource.h"
#pragma comment(lib, "ws2_32.lib")
#pragma comment(lib, "comctl32.lib")

#define BUF_SIZE 8192 // 8KO
#define M(szTXT) SetWindowText(g_hSTA, szTXT)

HWND g_hSTA, g_hBAR, g_hSpeed, g_hDlg;
BOOL g_bDownloading = false;

BOOL CALLBACK AppDlgProc(HWND hDlg, UINT uMsg, WPARAM wParam, LPARAM lParam);
DWORD WINAPI DownloadProc(void * szURL);
DWORD GetServerAddress(char * szURL);
int ParseHeaderHttp(char * buffer, int buffersize, int * sizeoffile);
char * GetFileNameFromURL(char * szURL);
int GetDocumentsDirectory(char * szbuf, int bufsize);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
	WSADATA wsa;
	if(WSAStartup(0x0202, &wsa)) return 0;
	DialogBoxParam(hInstance, "MainDialog", 0, AppDlgProc, 0);
	WSACleanup();
	return 0;
}

BOOL CALLBACK AppDlgProc(HWND hDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	static HANDLE hThread = 0;
	static HWND hURL;
	static char szURL[256];
	switch(uMsg) 
	{
	case WM_INITDIALOG:
		InitCommonControls();
		SetClassLong(hDlg, GCL_HICON,(long) "icone");
		g_hDlg = hDlg;
		hURL = GetDlgItem(hDlg, IDC_URL);
		g_hBAR = GetDlgItem(hDlg, IDC_BAR);
		g_hSpeed = GetDlgItem(hDlg, IDC_SPEED);
		g_hSTA = GetDlgItem(hDlg, IDC_STA);
		SetWindowText(g_hDlg, "Téléchargement");
	return 1;
	case WM_COMMAND:
		switch(LOWORD(wParam)) 
		{
		case IDOK:
			if(!g_bDownloading)
			{
				g_bDownloading = true;
				GetWindowText(hURL, szURL, 256);
				SendMessage(g_hBAR, PBM_SETPOS, 0, 0);
				if(hThread) CloseHandle(hThread);
				hThread = CreateThread(0, 0, DownloadProc, szURL, 0, 0);
			}
			return 0;
		case IDCANCEL:
			if(g_bDownloading)
			{
				if(IDNO == MessageBox(hDlg, "Fichier actuellement en cours de téléchargement.\r\nEtes vous sur de vouloir quitter ?", "Téléchargement en cours", MB_YESNO|MB_ICONWARNING))
					return 0;
			}
			CloseHandle(hThread);
			EndDialog(hDlg, 0);
		}
	}
return 0;
}

DWORD WINAPI DownloadProc(void * szURL)
{
	SOCKET s;
	sockaddr_in sin;
	WSAEVENT hEvent[1];
	WSANETWORKEVENTS NetworkEvent;
	HANDLE hFile;
	BYTE buffer[BUF_SIZE], *pBuffer;
	DWORD dwSize = 0, dwRecu = 0, dwEcrit = 0, dwEcritTotal = 0;
	DWORD dwLastEcritTotal = 0, dwDebit = 0, dwLastTickCount = 0;
	DWORD dwTickCountDebut = 0, dwTempRestant = 0, dwDebitMoyen = 0;
	char szTEMP[256], szLOCAL[256],  *szFileName;
	bool bHttpHeader = false;

	// I: initialisation de la connexion
	s = socket(AF_INET, SOCK_STREAM, 0);
	if(s == -1) {
		M("Erreur création socket."); 
		goto err_socket;}

	sin.sin_family = AF_INET;
	sin.sin_port   = htons(80);
	sin.sin_addr.S_un.S_addr = GetServerAddress((char*)szURL);

	hEvent[0] = WSACreateEvent();
	WSAEventSelect(s, hEvent[0], FD_READ | FD_CONNECT | FD_CLOSE);

	connect(s, (sockaddr*)&sin, sizeof(sin));
	M("Connexion au serveur...");

	// II: initialisation du fichier local 
	if(!GetDocumentsDirectory(szTEMP, 256)) strcpy(szTEMP, "c:\\");
	strcpy(szLOCAL, szTEMP);
	szFileName = GetFileNameFromURL((char*) szURL);
	strcat(szLOCAL, szFileName);
	hFile = CreateFile(szLOCAL, FILE_ALL_ACCESS, FILE_SHARE_WRITE, 0, CREATE_NEW, FILE_ATTRIBUTE_NORMAL, 0);
	if(hFile == INVALID_HANDLE_VALUE)
	{
		M("Erreur fichier.");
		goto err_socket;
	}

	// III: connexion, déconnexion, reception du fichier
	while(1)
	{	
		memset(&NetworkEvent, 0, sizeof(NetworkEvent));

		WSAWaitForMultipleEvents(1, hEvent, 0, WSA_INFINITE, 0);
		WSAEnumNetworkEvents(s, hEvent[0], &NetworkEvent);

		if(NetworkEvent.lNetworkEvents & FD_CONNECT)
		{
			// erreur a la connexion
			if(NetworkEvent.iErrorCode[FD_CONNECT_BIT]) {
				M("Erreur lors de la connexion.");
				CloseHandle(hFile); DeleteFile(szLOCAL);
				goto err_socket;}

			// si connexion ok, envoi de la requette
			strcpy(szTEMP, "GET ");
			strcat(szTEMP,(const char*) szURL);
			strcat(szTEMP, " HTTP/1.0\r\n\r\n");
			send(s, szTEMP, strlen(szTEMP), 0);
			M("Envoi de la requette http au serveur...");
		}

		if(NetworkEvent.lNetworkEvents & FD_READ)
		{
			dwRecu = 0;
			pBuffer = buffer;
			dwRecu = recv(s,(char*) buffer, BUF_SIZE, 0);

			//traitement du header
			if(!bHttpHeader)
			{
				int iHeaderLen;
				dwLastTickCount = dwTickCountDebut = GetTickCount(); // debut du download
				iHeaderLen = ParseHeaderHttp((char*)buffer, BUF_SIZE,(int*) &dwSize);
				if(!iHeaderLen)
				{
					M("Fichier introuvable.");
					CloseHandle(hFile); DeleteFile(szLOCAL);
					goto err_socket;
				}
				pBuffer += iHeaderLen; 
				dwRecu  -= iHeaderLen;
				bHttpHeader = true;
				M("Header HTTP recu.");
			}

			// ecriture dans le fichier
			WriteFile(hFile, pBuffer, dwRecu, &dwEcrit, 0);
			dwEcritTotal += dwEcrit;
			
			// affichage progressbar, infos, vitesse & temp restant
			SendMessage(g_hBAR, PBM_SETPOS, (int)(100 * ((double)dwEcritTotal/(double)dwSize)), 0);

			sprintf(szTEMP, "%s: %d/%d", szFileName, dwEcritTotal, dwSize);
			M(szTEMP);

			if(dwLastTickCount+1000 < GetTickCount())
			{
				// vitesse download
				dwDebit = (dwEcritTotal - dwLastEcritTotal) / 1024;
				dwLastTickCount = GetTickCount();
				dwLastEcritTotal = dwEcritTotal;
				sprintf(szTEMP, "%d ko/s", dwDebit);
				SetWindowText(g_hSpeed, szTEMP);

				// temp restant
				dwDebitMoyen = dwEcritTotal / (GetTickCount()-dwTickCountDebut+1);
				dwTempRestant = (dwSize-dwEcritTotal) / (dwDebitMoyen * 1000 + 1);
				sprintf(szTEMP, "Téléchargement [%d %s]", 
					     (dwTempRestant >= 60) ? dwTempRestant/60 : dwTempRestant,
					     (dwTempRestant >= 60) ? "min" : "sec");
				SetWindowText(g_hDlg, szTEMP);
			}

			// téléchargement fini
			if(dwSize == dwEcritTotal)
			{
				M("Téléchargement terminé.");
				goto err_file;
			}
		}

		if(NetworkEvent.lNetworkEvents & FD_CLOSE)
		{
			// verifie s'il ne reste plus rien a lire sur le socket
			do {
				memset(&NetworkEvent, 0, sizeof(NetworkEvent));
				WSAEnumNetworkEvents(s, 0, &NetworkEvent);
				if(NetworkEvent.lNetworkEvents & FD_READ)
				{
					dwRecu = 0;
					dwRecu = recv(s,(char*) buffer, BUF_SIZE, 0);
					WriteFile(hFile, buffer, dwRecu, &dwEcrit, 0);
					dwEcritTotal += dwEcrit;
					if(dwSize == dwEcritTotal) break;
				}
			}while(NetworkEvent.lNetworkEvents & FD_READ);
	
			if(dwSize == dwEcritTotal) M("Téléchargement terminé.");
			else M("Déconnecté du serveur.");
			goto err_file;
		}
	}

err_file:
	CloseHandle(hFile);
err_socket:
	closesocket(s);
	WSACloseEvent(hEvent[0]);
	SendMessage(g_hBAR, PBM_SETPOS, 0, 0);
	SetWindowText(g_hSpeed, 0);
	g_bDownloading = false;
	return 0;
}

// retourne un DWORD directement copiable dans sin_addr.S_un.S_addr (ip du serveur)
// szURL doit etre dans un buffer
DWORD GetServerAddress(char * szURL)
{
	hostent * serv;
	char * z;              // z mettra le zero final
	char * d = szURL;      // d pointera sur le debut du nom du serveur
	if(*d=='h' && *(d+1)=='t' && *(d+2)=='t' && *(d+3)=='p') d += 7; // 7 = http://
	z = d;
	while(*z != '/' && *z) z++; *z = 0; 
	serv = gethostbyname(d);
	*z = '/';
	if(!serv) return 0;
return (DWORD)*((DWORD*)serv->h_addr_list[0]);
}

// parse la 1ere réponse du serveur http apres une requette download de fichier
// extrait la taille du fichier, retourne la taille du header ou 0 si erreur
int ParseHeaderHttp(char * buffer, int buffersize, int * sizeoffile)
{
	char * c, * f;
	bool reponse_ok = false;
	c = buffer;
	f = c + buffersize;     // c ne dois jamais depasser f

	while(c < f) 
	{
		// on verifie que le serveur réponds bien 200
		if(*c=='2' && *(c+1)=='0' && *(c+2)=='0' && *(c+3)==32) reponse_ok = true;

		// taille du fichier dans ligne de forme: "Content-Length: 123456"
		if(*c =='\n') {
			if(!strncmp(c+1,"Content-Length:", 15)) {
				c += 17;
				*sizeoffile = atoi(c);}}

		// ligne vide = fin header http = debut fichier
		if(*c=='\r' && *(c+1)=='\n' && *(c+2)=='\r' && *(c+3)=='\n' && reponse_ok == true && *sizeoffile) {
			c += 4;
			return (int)(c - buffer);}
		c++;
	}
return 0;
}

// retourne un pointeur sur le nom du fichier dans une URL
char * GetFileNameFromURL(char * szURL)
{
	char * c = szURL;
	while(*c) c++;
	while(c > szURL && *c != '/') c--; 
return (char*)++c;
}

// trouve le chemin de Mes Documents, rajoute le '\' final
int GetDocumentsDirectory(char *szbuf, int bufsize)
{
	HKEY hKey;
	int size, l;
	char *c;
	if(RegOpenKeyEx(HKEY_CURRENT_USER, "Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Shell Folders", 0, KEY_QUERY_VALUE, &hKey))
		return 0;
	size = bufsize;
	l = RegQueryValueEx(hKey, "Personal", 0, 0, (BYTE*) szbuf, (DWORD*) &size);
	RegCloseKey(hKey); 
	if(l) return 0;
	c = szbuf + size - 1;
	if(*(c-1) != '\\') {*c++ = '\\'; *c = 0;}   
	return (c - szbuf);
}