More C help pls

The Bag · 03-11-2002, 01:14 PM

Hi I still writing my proxy server. I'm having trouble with the send commmand but I think its the way I'm trying to split the string thats causing the problems, because when I run the entire request string through it works.

Currently I'm trying

fname = "GET ";
temp = "\n\n";

sscanf(client_buffer,"GET http:// % [ ^/ ] % [ ^\n ] ", host, filename);

strcat(request, fname);
strcat(request, filename);
strcat(request, temp);

Where client_buffer is a char[1024] got with recv from my client, it holds the requested web page. I am trying to split it so host holds the web address & request holds the requested file (after catination, ie GET /index.html HTML V1 \n\n).

But when I pass request to the host (after getting a connection) the program hangs. This does not happen when client_buffer is passed (which defeats the purpose of a proxy).

Basically I think I need a different or better way to spilt the string. Please help & also point out any really obvious mistakes I've made. (pls igone the random variable defined for debug purposes that haven't been talken out).

The rest of the program:

PHP Code:



#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <unistd.h> 
#include <errno.h> 
#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <netdb.h> 
 
#define BACKLOG 10 
 
main(){ 
 
  struct sockaddr_in client_add; 
  struct sockaddr_in my_add; 
  struct sockaddr_in host_add; 
  struct hostent * server; 
 
 
  int portnum = 8080; 
  int port = 80; 
  char myname[50]; 
  int sock, client_sock, host_sock; 
  unsigned int c_add_len; 
  unsigned int flag; 
  int length = 50; 
 
  int buffer_size = 1024; 
  char client_buffer[1024]; 
  char data_buffer[1024]; 
 
  char * host = (char *)malloc(buffer_size * sizeof(char)); 
  char * request = (char *)malloc(buffer_size * sizeof(char)); 
  char * filename = (char *)malloc(buffer_size * sizeof(char)); 
  char * fname = (char *)malloc(buffer_size * sizeof(char)); 
  char * temp = (char *)malloc(buffer_size * sizeof(char)); 
 
  int size, thing; 
  int test, n, m, p, t, i; 
  unsigned int sin_size; 
  int count = 0; 
  int req_size; 
  int fetch_loop; 
  int host_start, host_end; 
  int bytesread; 
 
  fname = "GET "; 
  temp  = "\n\n"; 
 
    gethostname(myname, 50); 
    printf("started\n"); 
 
  my_add.sin_family = AF_INET; 
  my_add.sin_port = htons(portnum); 
  my_add.sin_addr.s_addr = INADDR_ANY; 
  memset(&(my_add.sin_zero), '\0',8); 
 
  sock = socket(AF_INET, SOCK_STREAM,0); 
 
  if(sock < 0){ 
    printf("QWERTY"); 
    close(sock); 
    return -1; 
  }else{ 
    printf("ok\n"); 
  } 
 
 
  if((bind(sock, (struct sockaddr *)&my_add, sizeof(struct sockaddr))) == -1 ){ 
    printf("dead\n"); 
    close(sock); 
  }else{ 
    printf("bound\n"); 
  } 
 
  /* loop infinitely */ 
 
  bytesread = 1; 
 
  while(bytesread != 0){ 
 
  if((listen(sock, 3)) < 0){ 
    printf("dies on listen"); 
    close(sock); 
    return 0; 
  }else{ 
    printf("listening\n"); 
  } 
 
  sin_size = sizeof(struct sockaddr_in); 
  client_sock = accept(sock, (struct sockaddr *)&client_add, &sin_size); 
 
  if(client_sock == -1){ 
    printf("DAMN IT\n"); 
    close(client_sock); 
    close(sock); 
    return 0; 
  }else{ 
    printf("accepted\n"); 
  } 
 
  /* Get address from client */ 
 
  printf("about to read"); 
  bytesread = recv(client_sock, client_buffer, 1024, 0); 
  printf("finshed recv"); 
 
  size = bytesread; 
  printf("%d", size);     
 
  if(size < 0){ 
    printf("Didn't read it"); 
    close(client_sock); 
    close(sock); 
    return 0; 
  }else{ 
    printf("We are recieving cap'in: "); 
  } 
 
  printf("%s\n", client_buffer); 
 
 
  sscanf(client_buffer,"GET [url]http://%[/url][/url][^/]%[^\n]", host, filename); 
  printf("%s\n", filename); 
 
  strcat(request, fname); 
  strcat(request, filename); 
  strcat(request, temp); 
 
 
  printf("%s\n", host); 
  printf("--------------------------------------\n"); 
  printf("%s\n", request); 
 
  printf("got host name\n"); 
 
 
  /* trying to connect to host*/ 
 
  host_sock = socket(AF_INET, SOCK_STREAM, 0); 
 
  if(host_sock < 0){ 
    printf("%s\n",strerror(errno)); 
    close(client_sock); 
    close(host_sock); 
    close(sock); 
    return -1; 
  } 
 
  printf("trying to get host\n"); 
  server = gethostbyname(host); 
 
  if(server == NULL){ 
    printf("%s\n",strerror(errno)); 
    close(client_sock); 
    close(host_sock); 
    close(sock); 
    return -1; 
  } 
 
  printf("looked up host\n"); 
 
 
  host_add.sin_family = AF_INET; 
  host_add.sin_addr.s_addr = inet_addr(inet_ntoa(* ((struct in_addr *)server->h_addr))); 
  host_add.sin_port = htons(port); 
  memset(&(my_add.sin_zero), '\0',8);   
 
  printf("trying to setup connection\n"); 
 
 
  /*Connnect to host*/ 
 
  thing = connect(host_sock, (struct sockaddr *)&host_add, sizeof(struct sockaddr)); 
 
  if(thing  == -1){ 
    perror ("connect"); 
    close(client_sock); 
    close(host_sock); 
    close(sock); 
    return -1; 
  }else{ 
    printf("Connection set up\n"); 
  } 
 
  /* requested file*/ 
   
  printf("%d\n",size); 
 
  host_end = 0; 
 
 
 
 
 
  host_end = send(host_sock, client_buffer, sizeof(client_buffer), 0); 
  printf("%s\n",request); 
/*    host_end = send(host_sock, request, sizeof(request),0); */ 
 
  if(host_end == -1){ 
    printf("connection lost\n"); 
    close(client_sock); 
    close(host_sock); 
    close(sock); 
    return 0; 
  }else{ 
    printf("request sent to server\n"); 
  } 
 
  /* Loop until fetch_loop is set to 0 indicatating the end of the file */ 
 
  printf("testing testing\n"); 
 
  fetch_loop = 1; 
 
  printf("%d\n",fetch_loop); 
 
 
  while(fetch_loop != 0){ 
 
    printf("in da loop\n"); 
    /* Get data from host */ 
     
    fetch_loop = recv(host_sock, data_buffer, 1024, 0); 
    printf("%d\n",fetch_loop); 
    if(fetch_loop < 0){ 
      printf("transfer failed\n"); 
      close(client_sock); 
      close(host_sock); 
      close(sock); 
      return 0; 
    }else{ 
      printf("read from host\n"); 
    } 
 
    /* send data to client */ 
    if(send(client_sock, data_buffer, fetch_loop, 0) < 0){ 
      printf("TF\n"); 
      close(client_sock); 
      close(host_sock); 
      close(sock); 
      return 0; 
    }else{ 
      printf("sent buffer to client\n"); 
    } 
 
 
  } 
 
    fetch_loop = 1; 
    n = 0; 
    close(host_sock); 
    close(client_sock); 
    sin_size = 0; 
    size = 0; 
 
    free(host); 
    free(request); 
    free(filename); 
 
    host = (char *)malloc(buffer_size * sizeof(char)); 
    request = (char *)malloc(buffer_size * sizeof(char)); 
    filename = (char *)malloc(buffer_size * sizeof(char)); 
     
  } 
 
  close(host_sock); 
  close(client_sock); 
  close(sock); 
 
}

nitr0gen · 03-11-2002, 01:41 PM

Hi dude...

If you take a closer look at your format string you will see that it's wrong...

look:

sscanf(client_buffer,"GET <a href="http://%" target="_blank">http://%</a>[/url][^/]%[^\n]", host, filename);

a format string should absolutly contain conversions character
%s string
%d integer
etc...
you only specify %
that's why it fucks up
and you close " as well few times in your html code... you cant do it as is...

and hummm... If I were you I would rather consider using strtok() function to parse your string in tokens instead...

so Good Luck

nitr0gen · 03-11-2002, 01:56 PM

and humm as matter of optimizing your code

do not malloc a buffer to 1024 directly hardcoded
use fstat() to read the higher block size for better I/O efficiency
declare a struct stat using st_blksize member

I recommand using read() and write() instead of recv(), send() respectivly.

I had experience writing a TCPIP tunnel software and it decreases overhead time..

nitr0gen

The Bag · 03-11-2002, 03:22 PM

How would you use strtok, I can only find sketchy details on it.

nitr0gen · 03-11-2002, 03:31 PM

man strtok
pretty easy prototype
char *strtok(char *s, const char *delim)

you specify s as your string
and seperate it using delimiter delim
i.e.
I have a string

char buf[] = "this is an example";
char *ptr;

ptr = strtok(buf, " ");
printf("first token: %s\n", ptr);
ptr = strtok(NULL, " ");
printf("second token: %s\n", ptr);

this following piece of code seperate the string in token with space as delimiter.
this would print like
first token: this
second token: is

at the first call you issue your string as first parameter and further calls you specify NULL...

hope you got it.. take a look at the man anyways its pretty easy to handle tokens

nitr0gen

The Bag · 03-11-2002, 03:49 PM

Thanks, it all makes sense now. As for the man pages I'm currently sitting at a windows machine, unfortunately.

nitr0gen · 03-11-2002, 03:51 PM

no problem
if you have any other question feel free to ask me

nitr0gen