I have one problem with HTTP request created by C++ sockets (Linux). I need to get some information's from API.
#include <iostream>
#include <ctype.h>
#include <cstring>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <unistd.h>
#include <sstream>
#include <fstream>
#include <string>
using namespace std;
int sock;
struct sockaddr_in client;
int PORT = 80;
int main(int argc, char const *argv[])
{
struct hostent * host = gethostbyname("api.themoviedb.org");
if ( (host == NULL) || (host->h_addr == NULL) ) {
cout << "Error retrieving DNS information." << endl;
exit(1);
}
bzero(&client, sizeof(client));
client.sin_family = AF_INET;
client.sin_port = htons( PORT );
memcpy(&client.sin_addr, host->h_addr, host->h_length);
sock = socket(AF_INET, SOCK_STREAM, 0);
if (sock < 0) {
cout << "Error creating socket." << endl;
exit(1);
}
if ( connect(sock, (struct sockaddr *)&client, sizeof(client)) < 0 ) {
close(sock);
cout << "Could not connect" << endl;
exit(1);
}
stringstream ss;
ss << "GET /3/movie/" << 550 << "?api_key=xxx HTTP/1.1\r\n"
<< "Host: api.themoviedb.org\r\n"
<< "Accept: application/json\r\n"
<< "\r\n\r\n";
string request = ss.str();
if (send(sock, request.c_str(), request.length(), 0) != (int)request.length()) {
cout << "Error sending request." << endl;
exit(1);
}
char cur;
while ( read(sock, &cur, 1) > 0 ) {
cout << cur;
}
return 0;
}
But the problem is that it takes too long. It start writing response to console but it ends in 9/10 and after it takes about 30 seconds to end. When i tried to change in loop from:
cout << cur;
To:
cout << cur << endl;
Then it write a complete result but after it the program lags for a while. What is wrong with this code? When i tried get response by classic curl from terminal everything was OK. Thanks for your help
Web server is probably holding the connection open awaiting your next HTTP request, which will never come. The server eventually times out and closes the connection. You can change this behavior by either:
requesting the server close the connection with a Connection: close header line in the request
parsing the response header to know when to stop reading once you have gotten the end of the response. See RFC 2616 Section 4.4 for the rules of how to detect the end of the response.
You could have used HTTP/1.0 as the version on the request, since 1.0 version determines that the server should close the connection after each request.
Related
I am trying to create a program that downloads data from websites using c++ low level networking.
Here is the code:
#include <iostream>
#include <string>
#include <string.h>
#include <netdb.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
int status, sock;
struct addrinfo hints;
struct addrinfo *servinfo;
int main(int argc, char** argv){
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
int MAXDATASIZE = 100;
char request[] = "GET /robots.txt HTTP/1.1\n";
char buf[MAXDATASIZE];
if((status = getaddrinfo(argv[1], argv[2], &hints, &servinfo)) != 0){
std::cout << "getaddrinfo: " << gai_strerror(status) << "\n";
return 2;
}
if((sock = socket(servinfo->ai_family, servinfo->ai_socktype, servinfo->ai_protocol)) == -1){
std::cout << "Error creating socket\n";
return 2;
}
if(connect(sock, servinfo->ai_addr, servinfo->ai_addrlen) == -1){
std::cout << "Error connecting to host " << argv[1] << " at port " << argv[2] << "\n";
return 2;
}
if((send(sock, request,strlen(request), 0)) == -1){
std::cout << "Error communicating with website\n";
return 2;
}
if(recv(sock, buf, MAXDATASIZE, 0) == -1){
std::cout << "Error recciving data from " << argv[1] << " at port " << argv[2] << "\n";
}
std::cout << buf << std::endl;
close(sock);
freeaddrinfo(servinfo);
}
When I try to connect to google, using www.google.com as the host and 80 as the port, it hangs at the recv() call.To test whether the request was the problem, I connected to google using telnet with the same request, and it worked. I also tried binding netcat to a port on my computer, and then connected to that port using my program. The request was sent properly to netcat, and when I responded with a test message, my program reccived it.
Does anyone know why google isn't sending the data?
I'm using fedora 32, if that might help
Your software is not hanging. Rather, the server is waiting for an indication that the client has finished sending the headers, which is indicated by sending an empty line. Until the client sends the blank line, the server cannot respond.
Change your request to:
char request[] = "GET /robots.txt HTTP/1.1\r\n\r\n";
I am currently trying to create a C++ TCP IP Client that can send a specific string to a server, which makes the server send back a string with some numbers I need to use.
Specifically I need to send the string "getpos", and only that.
This works perfectly on the first loop, but on the second loop and onward. Whenever I try to send "getpos" again, it will overlap "getpos" with the numbers I previously recieved from the server and send that like:
"getpos20,123,24"
It's like the buffer or something hasn't cleared.
My program works perfectly when connecting to a Python server, but not a C++ server.
I have looked through others with similar issues, and tried various fixes. Nothing has worked so far.
Here is my current client code (on Linux):
#include <iostream>
#include <sys/types.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <string.h>
#include <string>
int main()
{
// Create a socket
int sock = socket(AF_INET, SOCK_STREAM, 0);
if (sock == -1)
{
return 1;
}
// Create a hint structure for the server we're connecting with
int port = PORTHERE;
std::string ipAddress = "IPNUMBERHERE";
sockaddr_in hint;
hint.sin_family = AF_INET;
hint.sin_port = htons(port);
inet_pton(AF_INET, ipAddress.c_str(), &hint.sin_addr);
std::cout << "listening" << std::endl;
// Connect to the server on the socket
int connectRes = connect(sock, (sockaddr*)&hint, sizeof(hint));
if (connectRes == -1)
{
return 1;
}
std::cout << "connected" << std::endl;
// While loop:
char buf[4096];
int buflen = 1024;
while(true){
// Send to server
std::string getmypos = "getpos";
int sendRes = send(sock, getmypos.c_str(), getmypos.size(), 0);
if (sendRes == -1){
std::cout << "Could not send to server! Whoops!" << std::endl;
continue;
}
// Wait for response
memset(buf, 0, 4096);
int bytesReceived = recv(sock, buf, buflen, 0);
if (bytesReceived == -1)
{
std::cout << "There was an error getting response from server" << std::endl;
}
else
{
// Display response
std::cout << "SERVER> " << std::string(buf, bytesReceived) << std::endl;
sleep(1);
}
}
// Close the socket
close(sock);
return 0;
}
I'm new to C++ and am trying to setup a connection to a remote server but having problems getting it to work. Spec: Ubuntu 16.04, pre-installed g++ compiler and when I run the following code it returns "pre-standard C++":
if( __cplusplus == 201103L ) std::cout << "C++11\n" ;
else if( __cplusplus == 19971L ) std::cout << "C++98\n" ;
else std::cout << "pre-standard C++\n" ;
My code is as follows:
#include <iostream>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <unistd.h>
#include <netdb.h>
using namespace std;
int main() {
int client;
int portNum = 80;
bool isExit = false;
int bufsize = 1024;
char buffer[bufsize];
const char ip[] = "216.58.210.36"; //google ip for test connection
const char req[] = "GET / HTTP/1.1\nHost: www.google.com"; //test
char res[bufsize];
struct sockaddr_in server_addr;
client = socket(AF_INET, SOCK_STREAM, 0);
if (client < 0) {
cout << "\nError establishing socket..." << endl;
exit(1);
}
cout << "\n=> Socket client has been created..." << endl;
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(portNum);
inet_aton(ip, &server_addr.sin_addr);
if (connect(client,(struct sockaddr *)&server_addr, sizeof(server_addr)) == 0){
cout << "=> Connection to the server port number: " << portNum << endl;
}
send(client, req, bufsize, 0);
cout << "=> Awaiting confirmation from the server..." << endl;
recv(client, buffer, bufsize, 0);
cout << "=> Connection confirmed, response:" << buffer << endl;
cout << res << endl;
close(client);
return 0;
}
The client is created and the socket connects but the code hangs on the call to recv() and no response is received. I'm assuming that's because the request I'm sending is in the wrong format/data type/etc. Can anyone advise where I'm going wrong? Cheers!
You haven't sent a complete HTTP request so the server is waiting for more data.
You need to use \r\n as your line separator and your request has to end in a blank line:
const char req[] = "GET / HTTP/1.1\r\nHost: www.google.com\r\n\r\n";
Plus as others have commented you need to check for errors.
You are also sending 1024 bytes of data from a buffer which is much smaller.
I'm using libev + non-blocking sockets to send a request to a server. I'm using Keep Alive because I need to send future requests to the destination over this same connection.
Behavior
Run the program and it fetches the URL and logs to console, as expected.
After doing this, wait and don't push ctrl+c to exit the program.
Expected
App should stay open because event loop is waiting for future responses but should not console log anything after the initial response.
Actual
Leave the app running. After 30+ seconds, it will start to console log the same response over and over and over again without end.
Question
Why is libev calling my callback (example_cb) repeatedly when no new request was sent and no new response data was received? How can I fix this?
#include <ev.h>
#include <stdio.h>
#include <iostream>
#include <ctype.h>
#include <cstring>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <fcntl.h>
#include <netdb.h>
#include <netinet/in.h>
#include <unistd.h>
#include <sstream>
#include <fstream>
#include <string>
using namespace std;
void sendRequest(int sockfd)
{
puts("------");
puts("sendRequest() was called");
stringstream ss;
ss << "GET /posts/11 HTTP/1.1\r\n"
<< "Host: jsonplaceholder.typicode.com\r\n"
<< "Accept: application/json\r\n"
<< "\r\n";
string request = ss.str();
if (send(sockfd, request.c_str(), request.length(), 0) != (int)request.length()) {
cout << "Error sending request." << endl;
exit(1);
}
cout << "Request sent. No err occured." << endl;
}
static void delay_cb(EV_P_ ev_timer *w, int revents)
{
puts("------");
puts("delay_cb() was called");
sendRequest(3);
}
static void example_cb(EV_P_ ev_io *w, int revents)
{
puts("------");
puts("example_cb() was called");
int sockfd = 3;
size_t len = 80*1024, nparsed; // response must be <= 80 Kb
char buf[len];
ssize_t recved;
recved = recv(sockfd, &buf, len, 0);
if (recved < 0) {
perror("recved was <1");
}
// don't process keep alives
if (buf[0] != '\0') {
std::cout << buf << std::endl;
}
// clear buf
buf[0] = '\0';
std::cout << "buf after clear attempt: " << buf << std::endl;
}
int example_request()
{
std::string hostname = "jsonplaceholder.typicode.com";
int PORT = 80;
struct sockaddr_in client;
struct hostent * host = gethostbyname(hostname.c_str());
if (host == NULL || host->h_addr == NULL) {
cout << "Error retrieving DNS information." << endl;
exit(1);
}
bzero(&client, sizeof(client));
client.sin_family = AF_INET;
client.sin_port = htons( PORT );
memcpy(&client.sin_addr, host->h_addr, host->h_length);
// create a socket
int sockfd = socket(PF_INET, SOCK_STREAM, 0);
if (sockfd < 0) {
cout << "Error creating socket." << endl;
exit(1);
}
cout << "Socket created" << endl;
// enable keep alive
int val = 1;
setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &val, sizeof val);
if (connect(sockfd, (struct sockaddr *)&client, sizeof(client)) < 0) {
close(sockfd);
cout << "Could not connect" << endl;
exit(1);
}
cout << "Socket connected" << endl;
// make non-blocking
int status = fcntl(sockfd, F_SETFL, fcntl(sockfd, F_GETFL, 0) | O_NONBLOCK);
if (status == -1) {
perror("ERROR making socket non-blocking");
}
std::cout << "Socket set to non-blocking" << std::endl;
std::cout << "Sockfd is: " << sockfd << std::endl;
return sockfd;
}
int main(void)
{
// establish socket connection
int sockfd = example_request();
struct ev_loop *loop = EV_DEFAULT;
ev_io example_watcher;
ev_io_init(&example_watcher, example_cb, sockfd, EV_READ);
ev_io_start(loop, &example_watcher);
// used to send the request 2 sec later
ev_timer delay_watcher;
ev_timer_init(&delay_watcher, delay_cb, 2, 0.0);
ev_timer_start(loop, &delay_watcher);
ev_run(loop, 0);
return 0;
}
Edit: Code updated with suggestions from comments
The source of the problem is that you do not check recved == 0 condition which corresponds to the other side closing the connection. When that happens the OS sets the socket into "closed mode" which (at least under linux) is always ready for reading and subsequent calls to recv will always return 0.
So what you need to do is to check for that condition, call close(fd); on the file descriptor (possibly with shutdown before) and ev_io_stop on the associated watcher. If you wish to continue at that point then you have to open a new socket and eo_io_start new watcher.
I`m trying to make an email client but it doesn't work :/ Im trying to connect to google imap with SSL (without SSL i can make it) Code:
#include "StdAfx.h"
#include "openssl/ssl.h"
#include "iostream"
#include <cstdio>
#include <iostream>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <windows.h>
using namespace std;
#pragma comment(lib, "Ws2_32.lib")
#define BUFSIZE 1024
char buf[BUFSIZE];
char *msg;
WSADATA wsda;
int sock;
struct hostent *host;
struct sockaddr_in server_addr;
short int s_port = 993;
const char *s_ipaddr = "74.125.77.109";
int SSL_library_init();
SSL_METHOD *meth;
int main () {
SSL_load_error_strings();
SSL_library_init();
//RAND_seed(buf, BUFSIZE);
SSL_CTX *sslContext = SSL_CTX_new(SSLv23_client_method());
if (sslContext == NULL)
{
cout << "err\n";
}
SSL *sslConnection = SSL_new(sslContext);
if(sslConnection == NULL)
{
cout << "err\n";
}
WSAStartup(MAKEWORD(2,2), &wsda);
sock = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(s_port);
server_addr.sin_addr.s_addr = inet_addr(s_ipaddr);
if(server_addr.sin_addr.s_addr == INADDR_NONE)
{
host = NULL;
host = gethostbyname(s_ipaddr);
if(host == NULL)
{
return false;
}
memcpy(&server_addr.sin_addr, host->h_addr_list[0], host->h_length);
}
connect(sock, (struct sockaddr *) &server_addr, sizeof(server_addr));
SSL_set_fd(sslConnection, sock);
SSL_connect(sslConnection);
cout << "Connecting:\n";
SSL_read(sslConnection, buf, sizeof(buf)-1);
cout << buf << "\n";
cout << "Logging-in:\n";
msg = "a1 login emailapp123#gmail.com PASS\n";
SSL_write(sslConnection, msg, strlen(msg));
SSL_read(sslConnection, buf, sizeof(buf)-1);
cout << buf << "\n";
cout << "INBOX\n";
msg = "a2 SELECT INBOX\n";
SSL_write(sslConnection, msg, strlen(msg));
SSL_read(sslConnection, buf, sizeof(buf)-1);
cout << buf << "\n";
system("pause");
}
And thats what i receive:
Connecting:
* OK Gimap ready for requests from 195.150.156.162 y48if37710eei.45
Logging-in:
* CAPABILITY IMAP4rev1 UNSELECT LITERAL+ IDLE NAMESPACE QUOTA ID XLIST CHILDREN
X-GM-EXT-1 UIDPLUS COMPRESS=DEFLATE
a1 OK emailapp123#gmail.com authenticated (Success)
INBOX
What should I do to make the connection right?
Thanks for every advice :-)
Chris
You need to terminate all commands sent to an imap server with both a carriage return and a line feed. Send a2 SELECT INBOX\r\n and it should work.
seems you are not terminating line command with \r\n. Please refer RFC
http://www.faqs.org/rfcs/rfc3501.html