toralizer in c

使用c並運用tor完成一個簡單的proxy server

command to read c docs

system call man 2 socket
library call man 3 atoi

argv in c

int main(int argc, char *argv[])
      ./toralize   1.2.3.4     80
argv      0           1         2

Socket 4 RPC

socket 4 protocol

Send packet

 
		+----+----+----+----+----+----+----+----+----+----+....+----+
		| VN | cD | DSTPORT |      DSTIP        | USERID       |NULL|
		+----+----+----+----+----+----+----+----+----+----+....+----+
 # of bytes:	   1    1      2              4           variable       1

Use c to define

struct proxy_request
{
    int8 vn;
    int8 cd;
    int16 dstport;
    int32 dstip;
    unsigned char username[8];
};
 
typedef struct proxy_request Req;

Receive packet

		+----+----+----+----+----+----+----+----+
		| VN | cD | DSTPORT |      DSTIP        |
		+----+----+----+----+----+----+----+----+
 # of bytes:	   1    1      2              4

Use c to define

struct proxy_response
{
    int8 vn;
    int8 cd;
    // are not important
    int16 _;
    int32 __;
};
 
typedef struct proxy_response Res;

PORT Binary

Makefile

all:
	gcc toralize.c -o toralize

Tor proxy socket 4

int main(int argc, char *argv[])
{
    char *host;
    int port, s;
    struct sockaddr_in sock;
 
    if (argc < 3)
    {
        fprintf(stderr, "Usage: %s <host> <port> \n", argv[0]);
        return -1;
    }
 
    host = argv[1];
    port = atoi(argv[2]);
 
    s = socket(AF_INET, SOcK_STREAM, 0);
    if (s < 0)
    {
        perror("socket");
        return -1;
    }
 
    sock.sin_family = AF_INET;
    sock.sin_addr.s_addr = inet_addr(PROXY);
    sock.sin_port = htons(PROXYPORT);
 
    if (connect(s, (struct sockaddr *)&sock, sizeof(sock)))
    {
        perror("connect");
        return -1;
    };
 
    printf("connected to proxy \n");
    return 0;
}

Finish define Request packet use c

Req *request(const char *dstip, const int dstport)
{
    Req *req;
 
    req = malloc(reqsize);
 
    // sockets 4 protocal
    req->vn = 4;
    req->cd = 1;
    req->dstport = htons(dstport);
    req->dstip = inet_addr(dstip);
    strncpy(req->username, USERNAME, 8);
 
    return req;
};

Finish send req and receive use c

  Req *req;
  Res *res;
  char buf[ressize];
  // boolean
  int success;
    
  req = request(host, port);
  write(s, req, reqsize);
 
  memset(buf, 0, ressize);
  if (read(s, buf, ressize) < 1)
  {
     perror("read");
     free(req);
     close(s);
     
     return -1;
  };
 
  res = (Res *)buf;
  // 90 is the socket protocal means suceess
  success = (res->cd == 90);
  if (!success)
  {
     fprintf(stderr, "Unable to traverse"
                        "the proxy, error code: %d \n",
             res->cd);
 
     close(s);
     free(req);
     return -1;
  }
  printf("Successfully connected through the proxy to %s:%d\n", host, port);
  close(s);
  free(req);

return code in packet

    90: request granted
	91: request rejected or failed
	92: request rejected becasue SOcKS server cannot connect to
	    identd on the client
	93: request rejected because the client program and identd
	    report different user-ids

simulation HTTP HEAD

  char tmp[512];
  memset(tmp, 0, 512);
  snprintf(tmp, 512, "HEAD / HTTP/1.0\r\n"
                       "Host: www.networktechnology.org\r\n"
                       "\r\n");
  write(s, tmp, strlen(tmp));
 
  memset(tmp, 0, 512);
  read(s, tmp, 511);
  printf("'%s'\n", tmp);