HTTP errors while making a request through a proxy - c++

Question

I want to know how to make an HTTP request through a proxy using Socket.
I was looking through documentation on Internet, and many people said that to do it I must connect to the proxy server and send a packet with the following header:
send(Socket, "CONNECT http://icanhazip.com:80 HTTP/1.0\r\n\r\n", strlen("CONNECT http://icanhazip.com:80 HTTP/1.0\r\n\r\n"), 0);
That website returns the current public IP, but, unfortunately, every proxy server I tried returned errors instead of the webpage's HTML source.
This is my actual code:
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <iostream>
using namespace std;
int main()
{
try {
int Socket = socket(AF_INET, SOCK_STREAM, 0);
sockaddr_in SockAddr;
memset(&SockAddr, 0, sizeof(SockAddr));
SockAddr.sin_port = htons(80);
SockAddr.sin_family = AF_INET;
SockAddr.sin_addr.s_addr = inet_addr("198.169.246.30");
int iResult = connect(Socket, (struct sockaddr *)& SockAddr, sizeof(SockAddr));
if (iResult != 0) {
std::cout << "I can't connect :(.";
getchar();
return 1;
}
std::cout << "Connected.\n";
send(Socket, "CONNECT http://icanhazip.com:80 HTTP/1.1\r\n\r\n", strlen("CONNECT http://icanhazip.com:80 HTTP/1.1\r\n\r\n"), 0);
char buffer[10000];
int nDataLength;
while ((nDataLength = recv(Socket, buffer, 10000, 0)) > 0) {
int i = 0;
while (buffer[i] >= 32 || buffer[i] == '\n' || buffer[i] == '\r') {
std::cout << buffer[i];
i += 1;
}
}
iResult = close(Socket);
}
catch (...) {
}
return 0;
}
What can I do to fix it? Or, what other solution should I look into?

Answer 1

Old Chinese proverb say, "before writing code, better to read specification"
https://www.rfc-editor.org/rfc/rfc7230
by following links in the document:
A client sending a CONNECT request MUST send the authority form of
request-target (Section 5.3 of [RFC7230]); i.e., the request-target
consists of only the host name and port number of the tunnel
destination, separated by a colon. For example,
CONNECT server.example.com:80 HTTP/1.1
Host: server.example.com:80
source: https://www.rfc-editor.org/rfc/rfc7231#section-4.3.6