I am writing a simple downloader. I am trying to download jpg picture.
void accel::download(int threads){
char msg[] = "HEAD /logos/2011/cezanne11-hp.jpg HTTP/1.0\r\nConnection: close\r\n\r\n";
int back = send(socketC, (const char *)&msg, strlen(msg), 0);
char *buff = new char[500];
back = recv(socketC, buff, 500, 0);
cout << buff;
char *buff2 = new char[700];
char msg2[] = "GET /logos/2011/cezanne11-hp.jpg HTTP/1.0\r\nRange: bytes=0-400\r\nConnection: close\r\n\r\n";
back = send(socketC, (const char *)&msg2, strlen(msg2), 0);
back = recv(socketC, buff2, 700, 0);
cout << back;
}
TCP connection is already initialized and the first part of my code is working. It succesfuly sends HEAD message and receaves response. But when it tries to download the picture, the recv gets 0. What might be wrong?
Btw this is school project so I am not allowed to use some fancy libraries to perform this operation. This is full pictures address - http://www.google.com/logos/2011/cezanne11-hp.jpg
You don't recieve anything because you told the server that you didn't want to make a second request when you specified
Connection: close
In your HEAD request.
This tells the server that you're only going to make ONE request and not to bother waiting for a second.
Try changing your first request to a persistant 'keep-alive' connection.
"HEAD /logos/2011/cezanne11-hp.jpg HTTP/1.0\r\nConnection: keep-alive\r\n\r\n";
NOTE: If you don't want to server to go away you might want to change your second request to keep-alive too.
Generally speaking, HTTP closes the socket. (HTTP 1.1 has persistent (keep-alive) connections, though you seem to have asked the server to close the connection on you in your first command.)
So make sure that your socket is still open after your first receive; I'm willing to bet that it isn't.
Have you verified that the image is actually being sent to your client? Maybe you're not getting any response from the server.
Try using wireshark to inspect the actual network activity. That will let you see exactly what's being sent and received. It's possible you're not getting anything back from the server, or that there's an issue with your request that you might be able to spot in the actual network traffic.
After you follow through with what chrisaycock says you may want to add Host: to your requests. A lot of shared hosting around and IP only access is likely to start failing.
Related
std::string HTTPrequest = "GET /index.html HTTP/1.1\r\nHost: www.yahoo.com\r\nConnection: close\r\n\r\n";
write(socket, HTTPrequest.c_str(), sizeof(HTTPrequest));
char pageReceived[4096];
int bytesReceived = read(socket, pageReceived, 4096);
I've got an HTTP client program that I run from my terminal. I've also got a webserver program. Using the webserver as a test, I can verify that the socket creation and attachment works correctly.
I create the request as shown above, then write to the socket. Using print statements, I can see that the code moves beyond the write call. However, it hangs on the read call.
I can't figure out what's going on - my formatting looks correct on the request.
Any ideas? Everything seems to work perfectly fine when I connect to my webserver, but both www.yahoo.com and www.google.com cause a hang. I'm on Linux.
In C and C++, sizeof gives you the number of bytes required to hold a type, regardless of its contents. So you are not sending the full request, only sizeof(std::string) bytes. You want HTTPRequest.size() (which gives you the number of bytes the value stored in HTTPRequest takes), not sizeof(HTTPrequest) (which gives you the number of bytes a std::string itself requires).
I am trying to use CPP and SDL_Net to make a HTTP Client. I'm using a char [] buffer to send and receive information.
Basically, I connect to the site mentioned below on port 80:
strcpy(buffer,"GET / HTTP/1.0 \n host: nullfakenothing.freeriderwebhosting.com \n \n");
SDLNet_TCP_Send(sd, (void *)buffer, strlen(buffer)+1);
SDLNet_TCP_Recv(sd, (void *)buffer, 200)>0
But I can't get anything back (the program gets stuck on Recv). Am I using the protocol wrong or is there something against the whole TCP/HTML system?
Your HTTP protocol has spurious spaces and should have \r\n terminators. This is untested but the HTTP should be okay. You may want to add other headers.
char buffer[1024];
std::strcpy(buffer, "GET / HTTP/1.1\r\n");
std::strcat(buffer, "Host: nullfakenothing.freeriderwebhosting.com\r\n");
std::strcat(buffer, "\r\n");
SDLNet_TCP_Send(sd, (void*) buffer, strlen(buffer));
SDLNet_TCP_Recv(sd, (void*) buffer, sizeof(buffer));
What you send is not HTTP but instead something which looks a little bit like HTTP if you don't look to hard. Please make yourself comfortable with the specification (like RFC2616) or at least look at some packet dumps or working code to see what you need to do their exactly. Since lots of things are wrong it makes no sense to point out specific errors.
I am dealing with problem that after sending data successfully i recv the first response from the client but the second one after he put his details and submit not.
do you have any idea why this happend?
Here is my code:
sock->listenAndAccept();
string url="HTTP/1.1 302 Found \r\nContent-Type: text/html; charset=utf8 \r\nContent- Length:279\r\n\r\n<!DOCTYPE html><html><head><title>Creating an HTML Element</title></head><body><form name=\"input\" action=\"login.html\" method=\"get\">user name: <input type=\"text\" name=\"user\"><br>password: <input type=\"text\" name=\"password\"><input type=\"submit\" value=\"Submit\"></form></body></html>";
sock->send(url.data(),url.length());
char buffer[1000];
sock->recv(buffer, 1000);
cout<<buffer<<endl;
sock->recv(buffer, 1000);
cout<<buffer<<endl;
listen and accept function:
TCPSocket* TCPSocket::listenAndAccept(){
int rc = listen(socket_fd, 1);
if (rc<0){
return NULL;
}
size_t len = sizeof(peerAddr);
bzero((char *) &peerAddr, sizeof(peerAddr));
int connect_sock = accept(socket_fd, (struct sockaddr *)&peerAddr,(unsigned int *)&len);
return new TCPSocket(connect_sock,serverAddr,peerAddr);
}
recv function:
int TCPSocket::recv(char* buffer, int length){
return read(socket_fd,buffer,length);
}
TCP is stream oriented protocol. It might be possible that you have read all the messages in first recv. Check the size of received data and see if it matches the expected output.
Always always always (I can't say that often enough) check the return value of recv. recv will read up to the amount you have requested. If you're certain the amount you've requested is on its way then you must go into a loop around recv buffering incoming data until you've received what you expect to receive.
This kind of bug tends to sit there lurking unseen while you test on your local machine using the very fast localhost interface and then surfaces as soon as you start running the client and server on different hosts.
When you move on from your test code to actual code then you must also deal with zero length responses (client closed the socket) and error codes (<0 response).
Finally, please post your client code. There may be bugs there as well.
I am trying to make a simple http server with C++. I've followed the beej's guide of network programming in C++.
When I ran the server in some port (8080, 2127, etc.) it successfully send response to browser (Firefox) when it accessed via address bar with: localhost:PORT_NUMBER except in port 80.
This is the code i wrote:
printf("Server: Got connection from %s\n", this->client_ip);
if(!fork()) // This is the child process, fork() -> Copy and run process
{
close(this->server_socket); // Child doesn't need listener socket
// Try to send message to client
char message[] = "\r\nHTTP/1.1 \r\nContent-Type: text/html; charset=ISO-8859-4 \r\n<h1>Hello, client! Welcome to the Virtual Machine Web..</h1>";
int length = strlen(message); // Plus 1 for null terminator
int send_res = send(this->connection, message, length, 0); // Flag = 0
if(send_res == -1)
{
perror("send");
}
close(this->connection);
exit(0);
}
close(this->connection); // Parent doesn't need this;
The problem is, even I have added the header on very early of the response string, why does the browser not showing the HTML properly instead shows only plain text? It shows something like this:
Content-Type: text/html; charset=ISO-8859-4
<h1>Hello, client! Welcome to the Virtual Machine Web..</h1>
Not a big "Hello, client!.." string like a normally h1 tagged string. What is the problem? Am I missing something in the header?
Another question is, why is the server won't running in port 80? The error log in server says:
server: bind: Permission denied
server: bind: Permission denied
Server failed to bind
libc++abi.dylib: terminate called throwing an exception
Please help. Thank you. Edit: I'dont have any process on Port 80.
You need to terminate the HTTP response header with \r\n\r\n, rather than just \r\n. It should also start with something more like HTTP/1.1 200 OK\r\n, without the leading \r\n.
For your port problem, if you have nothing else running on the port in question, you may find that the socket created by the last run of your program is still sticking around. To work around this, you can use setsockopt to set the SO_REUSEADDR flag on the socket. (This is not recommended for general use, I believe because you may receive data not intended for your program, but for development it's extremely handy.)
Your request starts with \r\n when it shouldn't also it did not specify a status code and you need a blank line after all the headers.
char message[] = "HTTP/1.1 200 Okay\r\nContent-Type: text/html; charset=ISO-8859-4 \r\n\r\n<h1>Hello, client! Welcome to the Virtual Machine Web..</h1>";
As for your port 80 issue, some other application maybe bound to it.
you need to add "Content-length: ", and the length is your HTML code, just like this:
char msg[] = "HTTP/1.1 200 OK\r\nContent-Type: text/html\r\nContent-length: 20\r\n\r\n<h1>Hello World</h1>";
Symptom
I think, I messed up something, because both Mozilla Firefox and Google Chrome produce the same error: they don't receive the whole response the webserver sends them. CURL never misses, the last line of the quick-scrolling response is always "</html>".
Reason
The reason is, that I send response in more part:
sendHeaders(); // is calls sendResponse with a fix header
sendResponse(html_opening_part);
for ( ...scan some data... ) {
sendResponse(the_data);
} // for
sendResponse(html_closing_part)
The browsers stop receiving data between sendResponse() calls. Also, the webserver does not close() the socket, just at the end.
(Why I'm doing this way: the program I write is designed for non-linux system, it will run on an embedded computer. It has not too much memory, which is mostly occupied by lwIP stack. So, avoid collecting the - relativelly - huge webpage, I send it in parts. Browsers like it, no broken HTML occurred as under Linux.)
Environment
The platform is GNU/Linux (Ubuntu 32-bit with 3.0 kernel). My small webserver sends the stuff back to the client standard way:
int sendResponse(char* data,int length) {
int x = send(fd,data,length,MSG_NOSIGNAL);
if (x == -1) {
perror("this message never printed, so there's no error \n");
if (errno == EPIPE) return 0;
if (errno == ECONNRESET) return 0;
... panic() ... (never happened) ...
} // if send()
} // sendResponse()
And here's the fixed header I am using:
sendResponse(
"HTTP/1.0 200 OK\n"
"Server: MyTinyWebServer\n"
"Content-Type: text/html; charset=UTF-8\n"
"Cache-Control: no-store, no-cache\n"
"Pragma: no-cache\n"
"Connection: close\n"
"\n"
);
Question
Is this normal? Do I have to send the whole response with a single send()? (Which I'm working on now, until a quick solution arrives.)
If you read RFC 2616, you'll see that you should be using CR+LF for the ends of lines.
Aside from that, open the browser developer tools to see the exact requests they are making. Use a tool like Netcat to duplicate the requests, then eliminate each header in turn until it starts working.
Gotcha!
As #Jim adviced, I've tried sending same headers with CURL, as Mozilla does: fail, broken pipe, etc. I've deleted half of headers: okay. I've added back one by one: fail. Deleted another half of headers: okay... So, there is error, only if header is too long. Bingo.
As I've said, there're very small amount of memory in the embedded device. So, I don't read the whole request header, only 256 bytes of them. I need only the GET params and "Host" header (even I don't need it really, just to perform redirects with the same "Host" instead of IP address).
So, if I don't recv() the whole request header, I can not send() back the whole response.
Thanks for your advices, dudes!