ProxyServer/proxy_server.c at master · AustinWatersUNT/ProxyServer · GitHub

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/* Multiple simultaneous clients handled by threads; */
#include <unistd.h>
#include <pthread.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>  /* system type defintions */
#include <sys/socket.h> /* network system functions */
#include <netinet/in.h> /* protocol & struct definitions */
#include <arpa/inet.h>
#include <netdb.h>
#include <errno.h>

#define BACKLOG      5
#define BUF_SIZE     1024
#define LISTEN_PORT   8888
#define SERVER_PORT   80

int threadCount = BACKLOG;
void *client_handler(void *arg);
int getIpAddress(char*, char*);
int destinationSock(char*);
int blacklist(char*);

int main(int argc, char *argv[]){
  int status, *sock_tmp;
  pthread_t a_thread;
  void *thread_result;

  struct sockaddr_in addr_mine;
  struct sockaddr_in addr_remote;
  int sock_listen;
  int sock_aClient;
  int addr_size;
  int reuseaddr = 1;


  sock_listen = socket(AF_INET, SOCK_STREAM, 0);
  if (sock_listen < 0) {
    perror("socket() failed");
    exit(0);
  }

  memset(&addr_mine, 0, sizeof (addr_mine));
  addr_mine.sin_family = AF_INET;
  addr_mine.sin_addr.s_addr = htonl(INADDR_ANY);
  addr_mine.sin_port = htons((unsigned short)LISTEN_PORT);

  // /* Enable the socket to reuse the address */
  // if (setsockopt(sock_listen, SOL_SOCKET, SO_REUSEADDR, &reuseaddr,
  //   sizeof(int)) == -1) {
  // perror("setsockopt");
  //   close(sock_listen);
  // exit(1);
  // }

  status = bind(sock_listen, (struct sockaddr *) &addr_mine,
  sizeof (addr_mine));
  if (status < 0) {
    perror("bind() failed");
    close(sock_listen);
    exit(1);
  }

  status = listen(sock_listen, 5);
  if (status < 0) {
    perror("listen() failed");
    close(sock_listen);
    exit(1);
  }

  addr_size = sizeof(struct sockaddr_in);
  printf("waiting for a client\n");
  while(1) {
    if (threadCount < 1) {
      sleep(1);
    }

    sock_aClient = accept(sock_listen, (struct sockaddr *) &addr_remote,
    &addr_size);
    if (sock_aClient == -1){
      close(sock_listen);
      exit(1);
    }

    printf("Got a connection from %s on port %d\n",
    inet_ntoa(addr_remote.sin_addr),
    htons(addr_remote.sin_port));
    sock_tmp = malloc(1);
    *sock_tmp = sock_aClient;
    printf("thread count = %d\n", threadCount);
    threadCount--;
    status = pthread_create(&a_thread, NULL, client_handler,
    (void *) sock_tmp);
    if (status != 0) {
      perror("Thread creation failed");
      close(sock_listen);
      close(sock_aClient);
      free(sock_tmp);
      exit(1);
    }
  }

  return 0;
}

void *client_handler(void *sock_desc) {

  int msg_size;
  char ip[100];
  int sock_send;
  int i;
  int send_len, bytes_sent;
  char buf[BUF_SIZE];
  int sock = *(int*)sock_desc;

  printf("In client_handler\n");

  while ((msg_size = recv(sock, buf, BUF_SIZE, 0)) > 0) { //This grabs a from the browser

    buf[msg_size] = 0;
    char message[BUF_SIZE];
    strcpy(message, buf);
    char* url = strtok(message, "/");
    url = strtok(NULL, " ");

    printf("Weburl: %s\n", url);
    char tempUrl[100];
    strcpy(tempUrl, url);
    char* hostname;
    char* tempFileRoute;
    char fileRoute[200];
    strcpy(fileRoute, "/");
    if(strstr(url, "/") != NULL)
    {
      hostname = strtok(tempUrl, "/");
      tempFileRoute = strtok(NULL, "\0");
      strcat(fileRoute, tempFileRoute);
    }
    else
    {
      hostname = (char*) malloc((strlen(url) + 1) * sizeof(char));
      strcpy(hostname, url);
    }

    printf("hostname: %s\n", hostname);
    if(blacklist(hostname) == 0)
    {
      strcpy(buf, "HTTP/1.1 200\r\n");
      strcat(buf, "Content-Type: text/html; charset=UTF-8\r\n\r\n");
      strcat(buf, "<!DOCTYPE html><html><head><title>Blacklist Page</title></head><body><h1>BLACKLIST</h1><p>THIS SITE IS NOT ALLOWED ON THIS SERVER</p></body></html>");
      send_len=strlen(buf);
      bytes_sent=send(sock,buf,send_len,0);
    }
    else
    {
      int fail = getIpAddress(hostname, ip); //retrives the ip address for website and saves it to ip
      if(fail == 1)
      {
        strcpy(buf, "HTTP/1.1 404\r\n");
        strcat(buf, "Content-Type: text/html; charset=UTF-8\r\n\r\n");
        strcat(buf, "<!DOCTYPE html><html><head><title>Page Doesn't Exist</title></head><body><h1>404</h1><p>Webpage not found</p></body></html>");
        send_len=strlen(buf);
        bytes_sent=send(sock,buf,send_len,0);
      }
      else
      {
        FILE* inCache;
        char fileName[200];
        strcpy(fileName, hostname);
        strcat(fileName, ".txt");
        inCache =fopen(fileName, "r");
        if(inCache == NULL)
        {
          printf("Hasn't visited site yet\n");
          printf("\nSending IP: %s\n", ip); //prints the ip
          sock_send = destinationSock(ip); //creates a socket to that ip and port 80
          strcpy(buf, "GET ");
          strcat(buf, fileRoute);
          strcat(buf, " HTTP/1.1\r\n");
          strcat(buf, "Host: http://www.");
          strcat(buf, hostname);
          strcat(buf, "\r\n");
          strcat(buf, "Connection: keep-alive\r\n");
          strcat(buf, "Cache-Control: max-age=0\r\n");
          strcat(buf, "Accept: text/html,*/*\r\n");
          strcat(buf, "Accept-Encoding: gzip, deflate\r\n");
          strcat(buf, "User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.90 Safari/537.36\r\n");
          strcat(buf, "Accept-Language: en-US,en;q=0.8\r\n\r\n");

          printf("Sending Message:\n%s\n", buf);

          send_len=strlen(buf);
          bytes_sent=send(sock_send,buf,send_len,0);

          printf("\n\n");
          //this reads in the response 1024 characters and sends that 1024 characters to the browser
          //this is also where we would stream buf to a file as well for reading from cache
          FILE *fptr;
          fptr=fopen(fileName, "a+");
          if(fptr ==NULL)
          {
            printf("FAIL TO OPEN FILE\n");
            exit(1);
          }
          if(strcmp(hostname, "cse.unt.edu") == 0)
          {
            strcpy(buf, "HTTP/1.1 200\r\n");
            strcat(buf, "Content-Type: text/html; charset=UTF-8\r\n\r\n");
            send_len=strlen(buf);
            bytes_sent=send(sock,buf,send_len,0);
          }
          while ((msg_size = recv(sock_send, buf, BUF_SIZE, 0)) > 0) {
            buf[msg_size] = 0;
            char tempBuf[BUF_SIZE];
            char sendBuf[BUF_SIZE];
            strcpy(tempBuf, buf);
            strcpy(sendBuf, "");
            //This is out filter
            FILE *badWord= fopen("badwords.txt", "r");
            if(badWord == NULL) printf("missing bad words file");
            else
            {
              char ch;
              char toString[2];
              char bWord[50];
              strcpy(bWord, "");
              while( ( ch = fgetc(badWord) ) != EOF ) { //we read in each character
                if(ch == '\n')
                {
                  strcpy(tempBuf, buf);
                  char* pch2 = strtok(tempBuf, " ");
                  while(pch2 != NULL)
                  {
                    if(strcmp(pch2, bWord) == 0) strcat(sendBuf, "****");
                    else strcat(sendBuf, pch2);
                    strcat(sendBuf, " ");
                    pch2 = strtok(NULL, " ");
                  }
                  strcpy(buf, sendBuf);
                  strcpy(bWord, "");
                  strcpy(sendBuf, "");
                  strcpy(tempBuf, "");
                }
                else
                {
                  sprintf(toString, "%c",ch);
                  strcat(bWord, toString);
                }
              }
              fclose(badWord);
            }
            fprintf(fptr, "%s", buf);
            send_len=strlen(buf);
            bytes_sent=send(sock,buf,send_len,0);
          }
          fclose(fptr);
          printf("\n\nOut of Loop\n");
          strcpy(buf, "");
          close(sock_send);
        }
        else
        {
          printf("reading from cache\n\n");
          char ch;
          char sendBuf[BUF_SIZE];
          while( ( ch = fgetc(inCache) ) != EOF ) {
            sprintf(sendBuf, "%c",ch);
            send_len=strlen(sendBuf);
            bytes_sent=send(sock,sendBuf,send_len,0);
          }
          fclose(inCache);
        }
      }
    }
  }
  close(sock);
  free(sock_desc);
  threadCount++;
  // pthread_exit("Thank you for the CPU time");
}

int blacklist(char* hostname)
{
  if(strcmp(hostname, "facebook.com") == 0) return 0;
  else if(strcmp(hostname, "youtube.com") == 0) return 0;
  else if(strcmp(hostname, "hulu.com") == 0) return 0;
  else if(strcmp(hostname, "example.com") == 0) return 0;
  else if(strcmp(hostname, "virus.com") == 0) return 0;
  else return 1;
}

int getIpAddress(char* hostname, char* ip)
{
  int sockfd;
    struct addrinfo hints, *servinfo, *p;
    struct sockaddr_in *h;
    int rv;

    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC; // use AF_INET6 to force IPv6
    hints.ai_socktype = SOCK_STREAM;

    if ( (rv = getaddrinfo( hostname , "http" , &hints , &servinfo)) != 0)
    {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
        return 1;
    }

    // loop through all the results and connect to the first we can
    for(p = servinfo; p != NULL; p = p->ai_next)
    {
        h = (struct sockaddr_in *) p->ai_addr;
        strcpy(ip , inet_ntoa( h->sin_addr ) );
    }

    freeaddrinfo(servinfo); // all done with this structure
    return 0;
}

int destinationSock(char* ip)
{
  int sock_send;
  struct sockaddr_in addr_send;
  int i;

  sock_send=socket (PF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (sock_send < 0) {
    printf("socket() failed\n");
    exit(0);
  }
  else {
    printf("socket created\n");
  }

  /* create socket address structure to connect to */
  memset(&addr_send, 0, sizeof (addr_send)); /* zero out structure */
  addr_send.sin_family = AF_INET; /* address family */
  addr_send.sin_addr.s_addr = inet_addr(ip);
  addr_send.sin_port = htons((unsigned short)SERVER_PORT);

  /* connect to the server */
  i=connect(sock_send, (struct sockaddr *) &addr_send, sizeof (addr_send));
  if (i < 0) {
    printf("connect() failed\n");
    close(sock_send);
    exit(0);
  }
  else {
    printf("connect successful\n");
  }
  return sock_send;
}