"einfacher" Download einer HTML-Datei
This commit is contained in:
Stephan Richter
217
src/main.cpp
217
src/main.cpp
@@ -1,16 +1,100 @@
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#include <iostream>
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#include <fstream>
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#include <stdexcept> // runtime_error
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#include <sstream>
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#include <cstring>
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#include <unistd.h>
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#ifdef linux
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#include <sys/socket.h> // socket(), connect()
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#include <arpa/inet.h> // sockaddr_in
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#include <netdb.h> // gethostbyname(), hostent
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#include <arpa/inet.h> // inet_ntoa()
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#include <errno.h> // errno
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#else
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#include <winsock2.h>
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#endif
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// erzeugt eine Exception, verwendet dabei die globale Variable errno
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std::runtime_error CreateSocketError(){
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std::ostringstream temp;
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#ifdef linux
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temp << "Socket-Fehler #" << errno << ": " << strerror(errno);
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#else
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int error = WSAGetLastError();
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temp << "Socket-Fehler #" << error;
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char* msg;
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if(FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,NULL, error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),reinterpret_cast<char*>(&msg), 0, NULL)){
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try{
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temp << ": " << msg;
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LocalFree(msg);
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}catch(...){
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LocalFree(msg);
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throw;
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}
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}
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#endif
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return std::runtime_error(temp.str());
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}
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void SendAll(int socket, const char* const buf, const int size){
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int bytesSent = 0; // Anzahl Bytes die wir bereits vom Buffer gesendet haben
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do{
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int result = send(socket, buf + bytesSent, size - bytesSent, 0);
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if(result < 0) throw CreateSocketError();
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bytesSent += result;
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} while(bytesSent < size);
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}
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// Liest eine Zeile des Sockets in einen stringstream
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void GetLine(int socket, std::stringstream &line){
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for(char c; recv(socket, &c, 1, 0) > 0; line << c){
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if(c == '\n') return;
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}
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throw CreateSocketError();
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}
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// Entfernt das http:// vor dem URL
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void RemoveHttp(std::string& url){
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size_t pos = url.find("http://");
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if(pos != std::string::npos) url.erase(0, 7);
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}
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// Gibt die Dateiendung im URL zurück
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std::string GetFileEnding(std::string& URL){
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using namespace std;
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size_t pos = URL.rfind(".");
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if(pos == string::npos)return "";
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URL.erase(0, pos);
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string ending = ".";
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// Algorithmus um Sachen wie ?index=home nicht zuzulassen
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for(string::iterator it = URL.begin() + 1; it != URL.end(); ++it){
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if(isalpha(*it)){
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ending += *it;
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}else break;
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}
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return ending;
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}
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// Gibt den Hostnamen zurück und entfernt ihn aus der URL, sodass nur noch der Pfad übrigbleibt
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std::string RemoveHostname(std::string& URL){
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size_t pos = URL.find("/");
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if(pos == std::string::npos){
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std::string temp = URL;
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URL = "/";
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return temp;
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}
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std::string temp = URL.substr(0, pos);
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URL.erase(0, pos);
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return temp;
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}
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int main(){
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using namespace std;
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cout << "URL: ";
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string url;
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cin >> url; // User gibt URL der Datei ein, die herruntergeladen werden soll
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#ifndef linux
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WSADATA w;
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if(int result = WSAStartup(MAKEWORD(2,2), &w) != 0){
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@@ -19,33 +103,28 @@ int main(){
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}
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#endif
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cout << "Bitte gebe einen Hostnamen ein: ";
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string hostname;
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cin >> hostname;
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RemoveHttp(url);
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hostent *phe = gethostbyname(hostname.c_str());
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string hostname = RemoveHostname(url);
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hostent* phe = gethostbyname(hostname.c_str());
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if(phe == NULL){
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cout << "Host konnte nicht aufgeloest werden!" << endl;
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cout << "Host konnte nicht aufgelöst werden!" << endl;
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return 1;
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}
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cout << "\nHostname: " << phe->h_name << endl << "Aliases: ";
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for(char** p = phe->h_aliases; *p != 0; ++p) cout << *p << " ";
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cout << endl;
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if(phe->h_addrtype != AF_INET){
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cout << "Ungueltiger Adresstyp!" << endl;
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cout << "Ungültiger Adresstyp!" << endl;
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return 1;
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}
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if(phe->h_length != 4){
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cout << "Ungueltiger IP-Typ!" << endl;
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cout << "Ungültiger IP-Typ!" << endl;
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return 1;
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}
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int Socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
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int Socket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
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if(Socket == -1){
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cout << "Socket konnte nicht erstellt werden!" << endl;
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return 1;
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@@ -57,7 +136,7 @@ int main(){
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char** p = phe->h_addr_list; // p mit erstem Listenelement initialisieren
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int result; // Ergebnis von connect
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do {
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do{
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if(*p == NULL) {
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cout << "Verbindung fehlgschlagen!" << endl;
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return 1;
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@@ -71,9 +150,113 @@ int main(){
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cout << "Verbindung erfolgreich!" << endl;
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string request = "GET ";
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request += url; // z.B. /faq/index.html
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request += " HTTP/1.1\n";
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request += "Host: " + hostname + "\nConnection: close\n\n";
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try{
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SendAll(Socket, request.c_str(), request.size());
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int code;
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string Protokoll;
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stringstream firstLine; // Die erste Linie ist anders aufgebaut als der Rest
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do{
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GetLine(Socket, firstLine);
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firstLine >> Protokoll;
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firstLine >> code;
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// 100 = Continue
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if(code == 100) GetLine(Socket, firstLine); // Leere Zeile nach Continue ignorieren
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} while(code == 100);
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cout << "Protokoll: " << Protokoll << endl;
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if(code != 200){
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firstLine.ignore(); // Leerzeichen nach dem Statuscode ignorieren
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string msg;
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getline(firstLine, msg);
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cout << "Error #" << code << " - " << msg << endl;
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return 0;
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}
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bool chunked = false;
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const int noSizeGiven = -1;
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int size = noSizeGiven;
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while(true){
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stringstream sstream;
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GetLine(Socket, sstream);
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if(sstream.str() == "\r") break;// Header zu ende?
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string left; // Das was links steht
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sstream >> left;
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sstream.ignore(); // ignoriert Leerzeichen
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if(left == "Content-Length:") sstream >> size;
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if(left == "Transfer-Encoding:"){
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string transferEncoding;
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sstream >> transferEncoding;
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chunked = (transferEncoding == "chunked");
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}
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}
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string filename = "download" + GetFileEnding(url);
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cout << "Filename: " << filename << endl;
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fstream fout(filename.c_str(), ios::binary | ios::out);
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if(!fout){
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cout << "Could not create file!" << endl;
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return 1;
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}
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int recvSize = 0; // Empfangene Bytes insgesamt
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char buf[1024];
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int bytesRecv = -1; // Empfangene Bytes des letzten recv
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if(size != noSizeGiven){ // Wenn die Größe über Content-length gegeben wurde
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cout << "0%";
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while(recvSize < size){
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if((bytesRecv = recv(Socket, buf, sizeof(buf), 0)) <= 0) throw CreateSocketError();
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recvSize += bytesRecv;
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fout.write(buf, bytesRecv);
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cout << "\r" << recvSize * 100 / size << "%" << flush; // Mit \r springen wir an den Anfang der Zeile
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}
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}else{
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if(!chunked){
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cout << "Downloading... (Unknown Filesize)" << endl;
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while(bytesRecv != 0){ // Wenn recv 0 zurück gibt, wurde die Verbindung beendet
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if((bytesRecv = recv(Socket, buf, sizeof(buf), 0)) < 0) throw CreateSocketError();
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fout.write(buf, bytesRecv);
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}
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}else{
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cout << "Downloading... (Chunked)" << endl;
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while(true){
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stringstream sstream;
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GetLine(Socket, sstream);
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int chunkSize = -1;
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sstream >> hex >> chunkSize; // Größe des nächsten Parts einlesen
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if(chunkSize <= 0) break;
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cout << "Downloading Part (" << chunkSize << " Bytes)... " << endl;
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recvSize = 0; // Vor jeder Schleife wieder auf 0 setzen
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while(recvSize < chunkSize){
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int bytesToRecv = chunkSize - recvSize;
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if((bytesRecv = recv(Socket, buf, bytesToRecv > sizeof(buf) ? sizeof(buf) : bytesToRecv, 0)) <= 0) throw CreateSocketError();
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recvSize += bytesRecv;
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fout.write(buf, bytesRecv);
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cout << "\r" << recvSize * 100 / chunkSize << "%" << flush;
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}
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cout << endl;
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for(int i = 0; i < 2; ++i){
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char temp;
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recv(Socket, &temp, 1, 0);
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}
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}
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}
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}
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cout << endl << "Finished!" << endl;
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} catch(exception& e){
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cout << endl;
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cerr << e.what() << endl;
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}
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#ifdef linux
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close(Socket);
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close(Socket); // Verbindung beenden
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#else
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closesocket(Socket);
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closesocket(Socket); // Windows-Variante
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#endif
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}
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