Chapter 12, Problem 12.39HW

A.

Explanation of Solution

C code:

//Include Header file

#include <stdio.h>

#include "csapp.h"

//Define the maximum entry for blocked list

#define MAXIMUMSIZE 100

//Function declaration

int divideURI(char *URIName, char *hostName, char *portNumber, char *pName);

void parseBlockList(char *fName, char list[MAXIMUMSIZE][MAXLINE], int limit);

int blockedURIList(char *URIName, char list[MAXIMUMSIZE][MAXLINE]);

//Main function

int main(int argc, char **argv)

{

  //Declare required variable

  int i, listenfd, connfd;

  int clientfd;

  //Create socket

  socklen_t clientlen;

  //Create structure for client address

  struct sockaddr_storage clientaddr;

  //Create rio function

  rio_t cRio, sRio;

  char cbuffer[MAXLINE], sbuffer[MAXLINE];

  ssize_t ssn, ccn;

char methodName[MAXLINE], URIName[MAXLINE], versionNo[MAXLINE];

char hostName[MAXLINE], portNumber[MAXLINE], pName[MAXLINE];

  char block_list[MAXIMUMSIZE][MAXLINE];

  int logFileDes;

  char logFileBuffer[MAXLINE];

  //Check command line arguments

  if (argc != 2)

  {

    //Display message

    fprintf(stderr, "usage: %s <port>\n", argv[0]);

fprintf(stderr, "use default portNumber 5000\n");

    listenfd = Open_listenfd("5000");

  }

  else

  {

    listenfd = Open_listenfd(argv[1]);

  }

  //Open log files

logFileDes = Open("log.list", O_WRONLY | O_APPEND, 0);

  //Set memory for block list

  memset(block_list, '\0', MAXLINE * MAXIMUMSIZE);

  //Call function for parse file

parseBlockList("block.list", block_list, MAXIMUMSIZE);

  //Check condition

  while (1)

  {

    /* wait for connection as a server */

    clientlen = sizeof(struct sockaddr_storage);

    //Call accept method

connfd = Accept(listenfd, (SA *) &clientaddr, &clientlen);

    Rio_readinitb(&sRio, connfd);

    /* Check URI Name full path */

    if (!Rio_readlineb(&sRio, sbuffer, MAXLINE))

    {

      Close(connfd);

      continue;

    }

    //Display the uri path

sscanf(sbuffer, "%s %s %s", methodName, URIName, versionNo);

    /* Check blocked uri */

    if (blockedURIList(URIName, block_list))

    {

      printf("%s is blocked\n", URIName);

      Close(connfd);

      continue;

    }

    //Display the visit uri

sprintf(logFileBuffer, "visit url: %s\n", URIName);

Write(logFileDes, logFileBuffer, strlen(logFileBuffer));

    memset(hostName, '\0', MAXLINE);

    memset(portNumber, '\0', MAXLINE);

    memset(pName, '\0', MAXLINE);

    //Declare variable

    int res;

    /* Check if the given uri is separate */

if ((res = divideURI(URIName, hostName, portNumber, pName)) == -1)

    {

fprintf(stderr, "is not http protocol\n");

      Close(connfd);

      continue;

    }

    else if (res == 0)

    {

fprintf(stderr, "is not a abslute request path\n");

      Close(connfd);

      continue;

    }

    //Connect server as a client

    clientfd = Open_clientfd(hostName, portNumber);

    Rio_readinitb(&cRio, clientfd);

    //Send the first request

sprintf(sbuffer, "%s %s %s\n", methodName, pName, versionNo);

    Rio_writen(clientfd, sbuffer, strlen(sbuffer));

    printf("%s", sbuffer);

    do

    {

      /* Call next http requests */

ssn = Rio_readlineb(&sRio, sbuffer, MAXLINE);

      printf("%s", sbuffer);

      Rio_writen(clientfd, sbuffer, ssn);

    }

    while(strcmp(sbuffer, "\r\n"));

    //For server send reply back

while ((ccn = Rio_readlineb(&cRio, cbuffer, MAXLINE)) != 0)

      Rio_writen(connfd, cbu...

B.

Explanation of Solution

C code:

#include <stdio.h>

#include "csapp.h"

//Define the maximum entry for blocked list

#define MAXIMUMSIZE 100

//Function declaration

int divideURI(char *URIName, char *hostName, char *portName, char *pathName);

void parseBlockList(char *fName, char list[MAXIMUMSIZE][MAXLINE], int limit);

int blockedURIList(char *URIName, char list[MAXIMUMSIZE][MAXLINE]);

void *proxyThreadFunction(void *vargp);

//Declare variable for blocked url list

static char bList[MAXIMUMSIZE][MAXLINE];

//Declare variable for log file fd

static int logFileDesc;

//Main function

int main(int argc, char **argv)

{

  //Declare required variable

  int listenfd;

  //Create socket

  socklen_t clientlen;

  //Create structure for client address

  struct sockaddr_storage clientaddr;

  int *connfdp;

  pthread_t tid;

  //Check command line arguments

  if (argc != 2)

  {

    //Display message

    fprintf(stderr, "usage: %s <port>\n", argv[0]);

    fprintf(stderr, "use default port 5000\n");

    listenfd = Open_listenfd("5000");

  }

  else

  {

    listenfd = Open_listenfd(argv[1]);

  }

  //Open log files

logFileDesc = Open("log.list", O_WRONLY | O_APPEND, 0);

  //Set memory for block list 

  memset(bList, '\0', MAXLINE * MAXIMUMSIZE);

  //Call function for parse file

  parseBlockList("block.list", bList, MAXIMUMSIZE);

  //Check condition

  while (1)

  {

    /* wait for connection as a server */

    clientlen = sizeof(struct sockaddr_storage);

    connfdp = Malloc(sizeof(int));

    //Call accept method

*connfdp = Accept(listenfd, (SA *) &clientaddr, &clientlen);

    //Generate new thread

Pthread_create(&tid, NULL, proxyThreadFunction, connfdp);

  }

  //Close log file descriptor

  Close(logFileDesc);

}

//Function definition for proxy thread

void *proxyThreadFunction(void *vargp)

{

  //Create thread id

  pthread_t tid = Pthread_self();

  Pthread_detach(tid);

  int connfd = *(int*)vargp;

  Free(vargp);

  //Create rio function

  rio_t cRio, sRio;

/* Declare required variable for client and server buffer */

  char cBuffer[MAXLINE], sBuffer[MAXLINE];

ssize_t ssn, ccn;

/* Declare variable for method name, uri, version number, host name, port number and path name*/

char methodName[MAXLINE], URIName[MAXLINE], versionNumber[MAXLINE];

char hostName[MAXLINE], portName[MAXLINE], pathName[MAXLINE];

  char logFileBuffer[MAXLINE];

  int clientfd;

  Rio_readinitb(&sRio, connfd);

  /* Check URI Name full path */

  if (!Rio_readlineb(&sRio, sBuffer, MAXLINE))

  {

    Close(connfd);

    return NULL;

  }

  //Display the uri path

sscanf(sBuffer, "%s %s %s", methodName, URIName, versionNumber);

  /* Check blocked uri */

  if (blockedURIList(URIName, bList))

  {

printf("Thread %ld: %s is blocked\n", tid, URIName);

    Close(connfd);

    return NULL;

  }

  //Print the log visit

sprintf(logFileBuffer, "Thread %ld: visit url: %s\n", tid, URIName);

Write(logFileDesc, logFileBuffer, strlen(logFileBuffer));

  memset(hostName, '\0', MAXLINE);

  memset(portName, '\0', MAXLINE);

  memset(pathName, '\0', MAXLINE);

  int res;

  /* Check if the given uri is separate */

if ((res = divideURI(URIName, hostName, portName, pathName)) == -1)

  {

fprintf(stderr, "tid %ld: not http protocol\n", tid);

    Close(connfd);

    return NULL;

  }

  else if (res == 0)

  {

fprintf(stderr, "tid %ld: not a abslute request path\n", tid);

    Close(connfd);

    return NULL;

  }

  //Connect server as a client

  clientfd = Open_clientfd(hostName, portName);

  Rio_readinitb(&cRio, clientfd);

  //Send the first request

sprintf(sBuffer, "%s %s %s\n", methodName, pathName, versionNumber);

  Rio_writen(clientfd, sBuffer, strlen(sBuffer));

  printf("tid %ld: %s", tid, sBuffer);

  do

  {

    /* Call next http requests */

    ssn = Rio_readlineb(&sRio, sBuffer, MAXLINE);

    printf("Tid %ld: %s", tid, sBuffer);

    Rio_writen(clientfd, sBuffer, ssn);

  } while(strcmp(sBuffer, "\r\n"));

  //For server send reply back

while ((ccn = Rio_readlineb(&cRio, cBuffer, MAXLINE)) != 0)

    Rio_writen(connfd, cBuffer, ccn);

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