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proxy_server_with_cache.c
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proxy_server_with_cache.c
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#include "proxy_parse.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#include <time.h>
#include <sys/wait.h>
#include <errno.h>
#include <pthread.h>
#include <semaphore.h>
#include <time.h>
#define MAX_BYTES 4096 //max allowed size of request/response
#define MAX_CLIENTS 400 //max number of client requests served at a time
#define MAX_SIZE 200*(1<<20) //size of the cache
#define MAX_ELEMENT_SIZE 10*(1<<20) //max size of an element in cache
typedef struct cache_element cache_element;
struct cache_element{
char* data; //data stores response
int len; //length of data i.e.. sizeof(data)...
char* url; //url stores the request
time_t lru_time_track; //lru_time_track stores the latest time the element is accesed
cache_element* next; //pointer to next element
};
cache_element* find(char* url);
int add_cache_element(char* data,int size,char* url);
void remove_cache_element();
int port_number = 8080; // Default Port
int proxy_socketId; // socket descriptor of proxy server
pthread_t tid[MAX_CLIENTS]; //array to store the thread ids of clients
sem_t seamaphore; //if client requests exceeds the max_clients this seamaphore puts the
//waiting threads to sleep and wakes them when traffic on queue decreases
//sem_t cache_lock;
pthread_mutex_t lock; //lock is used for locking the cache
cache_element* head; //pointer to the cache
int cache_size; //cache_size denotes the current size of the cache
int sendErrorMessage(int socket, int status_code)
{
char str[1024];
char currentTime[50];
time_t now = time(0);
struct tm data = *gmtime(&now);
strftime(currentTime,sizeof(currentTime),"%a, %d %b %Y %H:%M:%S %Z", &data);
switch(status_code)
{
case 400: snprintf(str, sizeof(str), "HTTP/1.1 400 Bad Request\r\nContent-Length: 95\r\nConnection: keep-alive\r\nContent-Type: text/html\r\nDate: %s\r\nServer: VaibhavN/14785\r\n\r\n<HTML><HEAD><TITLE>400 Bad Request</TITLE></HEAD>\n<BODY><H1>400 Bad Rqeuest</H1>\n</BODY></HTML>", currentTime);
printf("400 Bad Request\n");
send(socket, str, strlen(str), 0);
break;
case 403: snprintf(str, sizeof(str), "HTTP/1.1 403 Forbidden\r\nContent-Length: 112\r\nContent-Type: text/html\r\nConnection: keep-alive\r\nDate: %s\r\nServer: VaibhavN/14785\r\n\r\n<HTML><HEAD><TITLE>403 Forbidden</TITLE></HEAD>\n<BODY><H1>403 Forbidden</H1><br>Permission Denied\n</BODY></HTML>", currentTime);
printf("403 Forbidden\n");
send(socket, str, strlen(str), 0);
break;
case 404: snprintf(str, sizeof(str), "HTTP/1.1 404 Not Found\r\nContent-Length: 91\r\nContent-Type: text/html\r\nConnection: keep-alive\r\nDate: %s\r\nServer: VaibhavN/14785\r\n\r\n<HTML><HEAD><TITLE>404 Not Found</TITLE></HEAD>\n<BODY><H1>404 Not Found</H1>\n</BODY></HTML>", currentTime);
printf("404 Not Found\n");
send(socket, str, strlen(str), 0);
break;
case 500: snprintf(str, sizeof(str), "HTTP/1.1 500 Internal Server Error\r\nContent-Length: 115\r\nConnection: keep-alive\r\nContent-Type: text/html\r\nDate: %s\r\nServer: VaibhavN/14785\r\n\r\n<HTML><HEAD><TITLE>500 Internal Server Error</TITLE></HEAD>\n<BODY><H1>500 Internal Server Error</H1>\n</BODY></HTML>", currentTime);
//printf("500 Internal Server Error\n");
send(socket, str, strlen(str), 0);
break;
case 501: snprintf(str, sizeof(str), "HTTP/1.1 501 Not Implemented\r\nContent-Length: 103\r\nConnection: keep-alive\r\nContent-Type: text/html\r\nDate: %s\r\nServer: VaibhavN/14785\r\n\r\n<HTML><HEAD><TITLE>404 Not Implemented</TITLE></HEAD>\n<BODY><H1>501 Not Implemented</H1>\n</BODY></HTML>", currentTime);
printf("501 Not Implemented\n");
send(socket, str, strlen(str), 0);
break;
case 505: snprintf(str, sizeof(str), "HTTP/1.1 505 HTTP Version Not Supported\r\nContent-Length: 125\r\nConnection: keep-alive\r\nContent-Type: text/html\r\nDate: %s\r\nServer: VaibhavN/14785\r\n\r\n<HTML><HEAD><TITLE>505 HTTP Version Not Supported</TITLE></HEAD>\n<BODY><H1>505 HTTP Version Not Supported</H1>\n</BODY></HTML>", currentTime);
printf("505 HTTP Version Not Supported\n");
send(socket, str, strlen(str), 0);
break;
default: return -1;
}
return 1;
}
int connectRemoteServer(char* host_addr, int port_num)
{
// Creating Socket for remote server ---------------------------
int remoteSocket = socket(AF_INET, SOCK_STREAM, 0);
if( remoteSocket < 0)
{
printf("Error in Creating Socket.\n");
return -1;
}
// Get host by the name or ip address provided
struct hostent *host = gethostbyname(host_addr);
if(host == NULL)
{
fprintf(stderr, "No such host exists.\n");
return -1;
}
// inserts ip address and port number of host in struct `server_addr`
struct sockaddr_in server_addr;
bzero((char*)&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(port_num);
bcopy((char *)host->h_addr,(char *)&server_addr.sin_addr.s_addr,host->h_length);
// Connect to Remote server ----------------------------------------------------
if( connect(remoteSocket, (struct sockaddr*)&server_addr, (socklen_t)sizeof(server_addr)) < 0 )
{
fprintf(stderr, "Error in connecting !\n");
return -1;
}
// free(host_addr);
return remoteSocket;
}
int handle_request(int clientSocket, ParsedRequest *request, char *tempReq)
{
char *buf = (char*)malloc(sizeof(char)*MAX_BYTES);
strcpy(buf, "GET ");
strcat(buf, request->path);
strcat(buf, " ");
strcat(buf, request->version);
strcat(buf, "\r\n");
size_t len = strlen(buf);
if (ParsedHeader_set(request, "Connection", "close") < 0){
printf("set header key not work\n");
}
if(ParsedHeader_get(request, "Host") == NULL)
{
if(ParsedHeader_set(request, "Host", request->host) < 0){
printf("Set \"Host\" header key not working\n");
}
}
if (ParsedRequest_unparse_headers(request, buf + len, (size_t)MAX_BYTES - len) < 0) {
printf("unparse failed\n");
//return -1; // If this happens Still try to send request without header
}
int server_port = 80; // Default Remote Server Port
if(request->port != NULL)
server_port = atoi(request->port);
int remoteSocketID = connectRemoteServer(request->host, server_port);
if(remoteSocketID < 0)
return -1;
int bytes_send = send(remoteSocketID, buf, strlen(buf), 0);
bzero(buf, MAX_BYTES);
bytes_send = recv(remoteSocketID, buf, MAX_BYTES-1, 0);
char *temp_buffer = (char*)malloc(sizeof(char)*MAX_BYTES); //temp buffer
int temp_buffer_size = MAX_BYTES;
int temp_buffer_index = 0;
while(bytes_send > 0)
{
bytes_send = send(clientSocket, buf, bytes_send, 0);
for(int i=0;i<bytes_send/sizeof(char);i++){
temp_buffer[temp_buffer_index] = buf[i];
// printf("%c",buf[i]); // Response Printing
temp_buffer_index++;
}
temp_buffer_size += MAX_BYTES;
temp_buffer=(char*)realloc(temp_buffer,temp_buffer_size);
if(bytes_send < 0)
{
perror("Error in sending data to client socket.\n");
break;
}
bzero(buf, MAX_BYTES);
bytes_send = recv(remoteSocketID, buf, MAX_BYTES-1, 0);
}
temp_buffer[temp_buffer_index]='\0';
free(buf);
add_cache_element(temp_buffer, strlen(temp_buffer), tempReq);
printf("Done\n");
free(temp_buffer);
close(remoteSocketID);
return 0;
}
int checkHTTPversion(char *msg)
{
int version = -1;
if(strncmp(msg, "HTTP/1.1", 8) == 0)
{
version = 1;
}
else if(strncmp(msg, "HTTP/1.0", 8) == 0)
{
version = 1; // Handling this similar to version 1.1
}
else
version = -1;
return version;
}
void* thread_fn(void* socketNew)
{
sem_wait(&seamaphore);
int p;
sem_getvalue(&seamaphore,&p);
printf("semaphore value:%d\n",p);
int* t= (int*)(socketNew);
int socket=*t; // Socket is socket descriptor of the connected Client
int bytes_send_client,len; // Bytes Transferred
char *buffer = (char*)calloc(MAX_BYTES,sizeof(char)); // Creating buffer of 4kb for a client
bzero(buffer, MAX_BYTES); // Making buffer zero
bytes_send_client = recv(socket, buffer, MAX_BYTES, 0); // Receiving the Request of client by proxy server
while(bytes_send_client > 0)
{
len = strlen(buffer);
//loop until u find "\r\n\r\n" in the buffer
if(strstr(buffer, "\r\n\r\n") == NULL)
{
bytes_send_client = recv(socket, buffer + len, MAX_BYTES - len, 0);
}
else{
break;
}
}
// printf("--------------------------------------------\n");
// printf("%s\n",buffer);
// printf("----------------------%d----------------------\n",strlen(buffer));
char *tempReq = (char*)malloc(strlen(buffer)*sizeof(char)+1);
//tempReq, buffer both store the http request sent by client
for (int i = 0; i < strlen(buffer); i++)
{
tempReq[i] = buffer[i];
}
//checking for the request in cache
struct cache_element* temp = find(tempReq);
if( temp != NULL){
//request found in cache, so sending the response to client from proxy's cache
int size=temp->len/sizeof(char);
int pos=0;
char response[MAX_BYTES];
while(pos<size){
bzero(response,MAX_BYTES);
for(int i=0;i<MAX_BYTES;i++){
response[i]=temp->data[pos];
pos++;
}
send(socket,response,MAX_BYTES,0);
}
printf("Data retrived from the Cache\n\n");
printf("%s\n\n",response);
// close(socketNew);
// sem_post(&seamaphore);
// return NULL;
}
else if(bytes_send_client > 0)
{
len = strlen(buffer);
//Parsing the request
ParsedRequest* request = ParsedRequest_create();
//ParsedRequest_parse returns 0 on success and -1 on failure.On success it stores parsed request in
// the request
if (ParsedRequest_parse(request, buffer, len) < 0)
{
printf("Parsing failed\n");
}
else
{
bzero(buffer, MAX_BYTES);
if(!strcmp(request->method,"GET"))
{
if( request->host && request->path && (checkHTTPversion(request->version) == 1) )
{
bytes_send_client = handle_request(socket, request, tempReq); // Handle GET request
if(bytes_send_client == -1)
{
sendErrorMessage(socket, 500);
}
}
else
sendErrorMessage(socket, 500); // 500 Internal Error
}
else
{
printf("This code doesn't support any method other than GET\n");
}
}
//freeing up the request pointer
ParsedRequest_destroy(request);
}
else if( bytes_send_client < 0)
{
perror("Error in receiving from client.\n");
}
else if(bytes_send_client == 0)
{
printf("Client disconnected!\n");
}
shutdown(socket, SHUT_RDWR);
close(socket);
free(buffer);
sem_post(&seamaphore);
sem_getvalue(&seamaphore,&p);
printf("Semaphore post value:%d\n",p);
free(tempReq);
return NULL;
}
int main(int argc, char * argv[]) {
int client_socketId, client_len; // client_socketId == to store the client socket id
struct sockaddr_in server_addr, client_addr; // Address of client and server to be assigned
sem_init(&seamaphore,0,MAX_CLIENTS); // Initializing seamaphore and lock
pthread_mutex_init(&lock,NULL); // Initializing lock for cache
if(argc == 2) //checking whether two arguments are received or not
{
port_number = atoi(argv[1]);
}
else
{
printf("Too few arguments\n");
exit(1);
}
printf("Setting Proxy Server Port : %d\n",port_number);
//creating the proxy socket
proxy_socketId = socket(AF_INET, SOCK_STREAM, 0);
if( proxy_socketId < 0)
{
perror("Failed to create socket.\n");
exit(1);
}
int reuse =1;
if (setsockopt(proxy_socketId, SOL_SOCKET, SO_REUSEADDR, (const char*)&reuse, sizeof(reuse)) < 0)
perror("setsockopt(SO_REUSEADDR) failed\n");
bzero((char*)&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(port_number); // Assigning port to the Proxy
server_addr.sin_addr.s_addr = INADDR_ANY; // Any available adress assigned
// Binding the socket
if( bind(proxy_socketId, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0 )
{
perror("Port is not free\n");
exit(1);
}
printf("Binding on port: %d\n",port_number);
// Proxy socket listening to the requests
int listen_status = listen(proxy_socketId, MAX_CLIENTS);
if(listen_status < 0 )
{
perror("Error while Listening !\n");
exit(1);
}
int i = 0; // Iterator for thread_id (tid) and Accepted Client_Socket for each thread
int Connected_socketId[MAX_CLIENTS]; // This array stores socket descriptors of connected clients
// Infinite Loop for accepting connections
while(1)
{
bzero((char*)&client_addr, sizeof(client_addr)); // Clears struct client_addr
client_len = sizeof(client_addr);
// Accepting the connections
client_socketId = accept(proxy_socketId, (struct sockaddr*)&client_addr,(socklen_t*)&client_len); // Accepts connection
if(client_socketId < 0)
{
fprintf(stderr, "Error in Accepting connection !\n");
exit(1);
}
else{
Connected_socketId[i] = client_socketId; // Storing accepted client into array
}
// Getting IP address and port number of client
struct sockaddr_in* client_pt = (struct sockaddr_in*)&client_addr;
struct in_addr ip_addr = client_pt->sin_addr;
char str[INET_ADDRSTRLEN]; // INET_ADDRSTRLEN: Default ip address size
inet_ntop( AF_INET, &ip_addr, str, INET_ADDRSTRLEN );
printf("Client is connected with port number: %d and ip address: %s \n",ntohs(client_addr.sin_port), str);
//printf("Socket values of index %d in main function is %d\n",i, client_socketId);
pthread_create(&tid[i],NULL,thread_fn, (void*)&Connected_socketId[i]); // Creating a thread for each client accepted
i++;
}
close(proxy_socketId); // Close socket
return 0;
}
cache_element* find(char* url){
// Checks for url in the cache if found returns pointer to the respective cache element or else returns NULL
cache_element* site=NULL;
//sem_wait(&cache_lock);
int temp_lock_val = pthread_mutex_lock(&lock);
printf("Remove Cache Lock Acquired %d\n",temp_lock_val);
if(head!=NULL){
site = head;
while (site!=NULL)
{
if(!strcmp(site->url,url)){
printf("LRU Time Track Before : %ld", site->lru_time_track);
printf("\nurl found\n");
// Updating the time_track
site->lru_time_track = time(NULL);
printf("LRU Time Track After : %ld", site->lru_time_track);
break;
}
site=site->next;
}
}
else {
printf("\nurl not found\n");
}
//sem_post(&cache_lock);
temp_lock_val = pthread_mutex_unlock(&lock);
printf("Remove Cache Lock Unlocked %d\n",temp_lock_val);
return site;
}
void remove_cache_element(){
// If cache is not empty searches for the node which has the least lru_time_track and deletes it
cache_element * p ; // Cache_element Pointer (Prev. Pointer)
cache_element * q ; // Cache_element Pointer (Next Pointer)
cache_element * temp; // Cache element to remove
//sem_wait(&cache_lock);
int temp_lock_val = pthread_mutex_lock(&lock);
printf("Remove Cache Lock Acquired %d\n",temp_lock_val);
if( head != NULL) { // Cache != empty
for (q = head, p = head, temp =head ; q -> next != NULL;
q = q -> next) { // Iterate through entire cache and search for oldest time track
if(( (q -> next) -> lru_time_track) < (temp -> lru_time_track)) {
temp = q -> next;
p = q;
}
}
if(temp == head) {
head = head -> next; /*Handle the base case*/
} else {
p->next = temp->next;
}
cache_size = cache_size - (temp -> len) - sizeof(cache_element) -
strlen(temp -> url) - 1; //updating the cache size
free(temp->data);
free(temp->url); // Free the removed element
free(temp);
}
//sem_post(&cache_lock);
temp_lock_val = pthread_mutex_unlock(&lock);
printf("Remove Cache Lock Unlocked %d\n",temp_lock_val);
}
int add_cache_element(char* data,int size,char* url){
// Adds element to the cache
// sem_wait(&cache_lock);
int temp_lock_val = pthread_mutex_lock(&lock);
printf("Add Cache Lock Acquired %d\n", temp_lock_val);
int element_size=size+1+strlen(url)+sizeof(cache_element); // Size of the new element which will be added to the cache
if(element_size>MAX_ELEMENT_SIZE){
//sem_post(&cache_lock);
// If element size is greater than MAX_ELEMENT_SIZE we don't add the element to the cache
temp_lock_val = pthread_mutex_unlock(&lock);
printf("Add Cache Lock Unlocked %d\n", temp_lock_val);
// free(data);
// printf("--\n");
// free(url);
return 0;
}
else
{ while(cache_size+element_size>MAX_SIZE){
// We keep removing elements from cache until we get enough space to add the element
remove_cache_element();
}
cache_element* element = (cache_element*) malloc(sizeof(cache_element)); // Allocating memory for the new cache element
element->data= (char*)malloc(size+1); // Allocating memory for the response to be stored in the cache element
strcpy(element->data,data);
element -> url = (char*)malloc(1+( strlen( url )*sizeof(char) )); // Allocating memory for the request to be stored in the cache element (as a key)
strcpy( element -> url, url );
element->lru_time_track=time(NULL); // Updating the time_track
element->next=head;
element->len=size;
head=element;
cache_size+=element_size;
temp_lock_val = pthread_mutex_unlock(&lock);
printf("Add Cache Lock Unlocked %d\n", temp_lock_val);
//sem_post(&cache_lock);
// free(data);
// printf("--\n");
// free(url);
return 1;
}
return 0;
}