Wsrtjtyk

I am trying to put together a C code that makes an HTTP GET request to a local IP address (in my network) that has a webpage runing on port 80. The request should return the index.html.

The code works for a website with a real IP that has a DNS (I have tested with www.olx.ro and its IP), but when I try to put the local IP (which is 10.74.4.10), I get a 400 Bad Request response..

This is the code:

#include <sys/socket.h>

#include <sys/types.h>

#include <netinet/in.h>

#include <netdb.h>

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <unistd.h>

#include <errno.h>

#include <arpa/inet.h>



int main(void)

{

  int byte_count;

  int sockfd = 0,n = 0;

  char recvBuff[9000];

  struct sockaddr_in serv_addr;



  memset(recvBuff, '0' ,sizeof(recvBuff));

  if((sockfd = socket(AF_INET, SOCK_STREAM, 0))< 0)

    {

      printf("n Error : Could not create socket n");

      return 1;

    }

  else printf("Created socket successfully.n");



  printf("n");



  serv_addr.sin_family = AF_INET;

  serv_addr.sin_port = htons(80);

  serv_addr.sin_addr.s_addr = inet_addr("10.74.4.10");

  if(connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr))<0)

    {

      printf("n Error : Connect Failed n");

      return 1;

    }

  else printf("Connected successfully. n ");



  printf("n n");



  char *header = "GET /index.html HTTP/1.0rnHost:10.74.4.10:80rnrn";

  send(sockfd,header,strlen(header),0);



  byte_count = recv(sockfd,recvBuff,sizeof(recvBuff),0);

  printf("Received %d bytes of data in bufn",byte_count);

  printf("n");

  printf("%.*s",byte_count,recvBuff);  



  return 0;

}

If I change inet_addr("10.74.4.10") to inet_addr("2.16.128.73"), and "GET /index.html HTTP/1.0rnHost:10.74.4.10:80rnrn" to "GET /index.html HTTP/1.0rnHost:www.olx.ro:80rnrn", then the code works as intended.

Also, I would like to mention I use Repl.it as C compiler.

EDIT: I forgot to mention, the code stops at connect(). I have tried using bind(), still doesn't work. Maybe it's because I am trying to connect to a privileged port (80), with an online C compiler that cannot have root access?

... but when I try to put the local IP (which is 10.74.4.10), I get a 400 Bad Request response.

While you send a valid HTTP request you tell the server using the Host header that you want to access the hostname 10.74.4.10 configured at the server. If this works or not depends on the servers configuration. For example if the server is configured to only accept requests for the name example.com and to consider everything else wrong it will only accept requests with Host: example.com but not with Host: 10.74.4.10 even if this might be the IP address of the server.

... I forgot to mention, the code stops at connect()

This makes no sense at at all. If you get a 400 Bad Request as you first claim the connection to the site need to be successful first, which means it could not have stopped in connect.