MultiThreadedProxyServerClient/proxy_server_with_cache.c at main · sujay26p/MultiThreadedProxyServerClient · GitHub

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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 <pthread.h>
#include <semaphore.h>

#define MAX_BYTES 4096
#define MAX_CLIENTS 400
#define MAX_SIZE 200*(1<<20)
#define MAX_ELEMENT_SIZE 10*(1<<20)

typedef struct cache_element cache_element;

struct cache_element {
    char* data;
    int len;
    char* url;
    time_t lru_time_track;
    cache_element* next;
};

cache_element* find(char* url);
int add_cache_element(char* data, int size, char* url);
void remove_cache_element();

int port_number = 8080;
int proxy_socketId;
pthread_t tid[MAX_CLIENTS];
sem_t seamaphore;
pthread_mutex_t lock;

cache_element* head;
int cache_size;

char* make_cache_key(const char* host, const char* path) {
    if (path == NULL || strlen(path) == 0)
        path = "/";
    char* key = (char*)malloc(strlen(host) + strlen(path) + 2);
    sprintf(key, "%s%s", host, path);
    return key;
}

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\n\r\n<HTML><HEAD><TITLE>400 Bad Request</TITLE></HEAD><BODY><H1>400 Bad Request</H1></BODY></HTML>", currentTime);
            break;
        case 404:
            snprintf(str, sizeof(str), "HTTP/1.1 404 Not Found\r\nContent-Length: 91\r\nConnection: keep-alive\r\nContent-Type: text/html\r\nDate: %s\r\n\r\n<HTML><HEAD><TITLE>404 Not Found</TITLE></HEAD><BODY><H1>404 Not Found</H1></BODY></HTML>", currentTime);
            break;
        default:
            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\n\r\n<HTML><HEAD><TITLE>500 Internal Server Error</TITLE></HEAD><BODY><H1>500 Internal Server Error</H1></BODY></HTML>", currentTime);
            break;
    }

    send(socket, str, strlen(str), 0);
    return 1;
}

int connectRemoteServer(char* host_addr, int port_num) {
    int remoteSocket = socket(AF_INET, SOCK_STREAM, 0);
    if (remoteSocket < 0) return -1;

    struct hostent* host = gethostbyname(host_addr);
    if (!host) return -1;

    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);

    if (connect(remoteSocket, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0)
        return -1;

    return remoteSocket;
}

int handle_request(int clientSocket, ParsedRequest* request, char* cacheKey) {
    char* buf = (char*)malloc(MAX_BYTES);
    snprintf(buf, MAX_BYTES, "GET %s %s\r\n", request->path, request->version);

    if (ParsedHeader_set(request, "Connection", "close") < 0)
        printf("set header failed\n");

    if (!ParsedHeader_get(request, "Host"))
        ParsedHeader_set(request, "Host", request->host);

    size_t len = strlen(buf);
    if (ParsedRequest_unparse_headers(request, buf + len, MAX_BYTES - len) < 0)
        printf("unparse failed\n");

    int port = request->port ? atoi(request->port) : 80;
    int remoteSocket = connectRemoteServer(request->host, port);
    if (remoteSocket < 0) return -1;

    send(remoteSocket, buf, strlen(buf), 0);

    char recv_buf[MAX_BYTES];
    int total = 0;
    char* response = malloc(MAX_BYTES);
    int cap = MAX_BYTES;

    int n;
    while ((n = recv(remoteSocket, recv_buf, MAX_BYTES, 0)) > 0) {
        send(clientSocket, recv_buf, n, 0);
        if (total + n >= cap) {
            cap *= 2;
            response = realloc(response, cap);
        }
        memcpy(response + total, recv_buf, n);
        total += n;
    }
    response[total] = '\0';

    add_cache_element(response, total, cacheKey);

    close(remoteSocket);
    free(buf);
    return 0;
}

int checkHTTPversion(char* msg) {
    if (strncmp(msg, "HTTP/1.1", 8) == 0 || strncmp(msg, "HTTP/1.0", 8) == 0)
        return 1;
    return -1;
}

void* thread_fn(void* socketNew) {
    sem_wait(&seamaphore);
    int p;
    sem_getvalue(&seamaphore, &p);
    printf("semaphore value:%d\n", p);

    int socket = *((int*)socketNew);
    char* buffer = calloc(MAX_BYTES, sizeof(char));

    int bytes = recv(socket, buffer, MAX_BYTES, 0);
    while (bytes > 0 && strstr(buffer, "\r\n\r\n") == NULL)
        bytes = recv(socket, buffer + strlen(buffer), MAX_BYTES - strlen(buffer), 0);

    if (bytes <= 0) {
        close(socket);
        free(buffer);
        sem_post(&seamaphore);
        return NULL;
    }

    ParsedRequest* request = ParsedRequest_create();
    if (ParsedRequest_parse(request, buffer, strlen(buffer)) < 0) {
        printf("Parsing failed\n");
        sendErrorMessage(socket, 400);
    } else if (!strcmp(request->method, "GET") && request->host && request->path && checkHTTPversion(request->version)) {
        char* cacheKey = make_cache_key(request->host, request->path);
        cache_element* found = find(cacheKey);

        if (found) {
            printf("Data retrived from the Cache\n");
            int pos = 0;
            while (pos < found->len) {
                int to_send = (found->len - pos > MAX_BYTES) ? MAX_BYTES : (found->len - pos);
                send(socket, found->data + pos, to_send, 0);
                pos += to_send;
            }
        } else {
            if (handle_request(socket, request, cacheKey) < 0)
                sendErrorMessage(socket, 500);
        }

        free(cacheKey);
    } else {
        sendErrorMessage(socket, 400);
    }

    ParsedRequest_destroy(request);
    close(socket);
    free(buffer);
    sem_post(&seamaphore);
    return NULL;
}

int main(int argc, char* argv[]) {
    if (argc == 2) port_number = atoi(argv[1]);
    else { printf("Usage: %s <port>\n", argv[0]); exit(1); }

    sem_init(&seamaphore, 0, MAX_CLIENTS);
    pthread_mutex_init(&lock, NULL);

    struct sockaddr_in server_addr, client_addr;
    proxy_socketId = socket(AF_INET, SOCK_STREAM, 0);
    int reuse = 1;
    setsockopt(proxy_socketId, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));

    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port_number);
    server_addr.sin_addr.s_addr = INADDR_ANY;
    bind(proxy_socketId, (struct sockaddr*)&server_addr, sizeof(server_addr));
    listen(proxy_socketId, MAX_CLIENTS);
    printf("Binding on port: %d\n", port_number);

    int i = 0, client_socket;
    socklen_t client_len = sizeof(client_addr);
    int client_sockets[MAX_CLIENTS];

    while (1) {
        client_socket = accept(proxy_socketId, (struct sockaddr*)&client_addr, &client_len);
        if (client_socket < 0) continue;

        client_sockets[i] = client_socket;
        pthread_create(&tid[i], NULL, thread_fn, &client_sockets[i]);
        i = (i + 1) % MAX_CLIENTS;
    }

    close(proxy_socketId);
    return 0;
}

// ---------------- CACHE MANAGEMENT --------------------

cache_element* find(char* url) {
    pthread_mutex_lock(&lock);
    cache_element* site = head;
    while (site) {
        if (!strcmp(site->url, url)) {
            site->lru_time_track = time(NULL);
            pthread_mutex_unlock(&lock);
            return site;
        }
        site = site->next;
    }
    pthread_mutex_unlock(&lock);
    return NULL;
}

void remove_cache_element() {
    pthread_mutex_lock(&lock);
    cache_element *prev = NULL, *curr = head, *oldest = head, *oldest_prev = NULL;

    while (curr && curr->next) {
        if (curr->next->lru_time_track < oldest->lru_time_track) {
            oldest = curr->next;
            oldest_prev = curr;
        }
        curr = curr->next;
    }

    if (oldest == head)
        head = head->next;
    else if (oldest_prev)
        oldest_prev->next = oldest->next;

    cache_size -= oldest->len + strlen(oldest->url) + sizeof(cache_element);
    free(oldest->data);
    free(oldest->url);
    free(oldest);
    pthread_mutex_unlock(&lock);
}

int add_cache_element(char* data, int size, char* url) {
    pthread_mutex_lock(&lock);
    int new_size = size + strlen(url) + sizeof(cache_element);
    if (new_size > MAX_ELEMENT_SIZE) {
        pthread_mutex_unlock(&lock);
        return 0;
    }

    while (cache_size + new_size > MAX_SIZE)
        remove_cache_element();

    cache_element* elem = malloc(sizeof(cache_element));
    elem->data = malloc(size);
    memcpy(elem->data, data, size);
    elem->len = size;
    elem->url = strdup(url);
    elem->lru_time_track = time(NULL);
    elem->next = head;
    head = elem;
    cache_size += new_size;
    pthread_mutex_unlock(&lock);
    return 1;
}