server-client-network/Server.c

#include "Server.h"
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <unistd.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>  
#include "Stream.h" 

void serverInitDefaults(Server* s)
{
    s->maxClients = -1;
    s->port = -1;
    s->threads = NULL;
    s->clientSockets = NULL;
    s->connectSocket = -1;
    
    s->hAmount = -1;
    s->hIndex = -1;
    s->handlers = NULL;
}

int serverInit(Server* s, int maxClients, short port)
{
    s->maxClients = maxClients;
    s->port = port;
    s->hAmount = 0;
    s->hIndex = 0;
    
    // initialize storage for clients
    s->threads = malloc(sizeof(pthread_t) * maxClients);
    s->clientSockets = malloc(sizeof(int) * maxClients);
    
    for(int i = 0; i < maxClients; i++)
    {
        s->threads[i] = -1;
        s->clientSockets[i] = -1;
    }
    
    // create the socket for clients to connect
    s->connectSocket = socket(AF_INET, SOCK_STREAM, 0);
    if(s->connectSocket == -1)
    {
        perror("Cannot create socket");
        serverRemove(s);
        return -1;
    }
    
    // prevents clients from blocking the port if the server exits
    struct linger sl;
    sl.l_onoff = 1;
    sl.l_linger = 0;
    if(setsockopt(s->connectSocket, SOL_SOCKET, SO_LINGER, &sl, sizeof(struct linger)) == -1)
    {
        perror("Cannot set non lingering");
        serverRemove(s);
        return -1;
    }
    
    // specifies data of the port and binds it
    struct sockaddr_in connectSocketData;
    memset(&connectSocketData, 0, sizeof(struct sockaddr_in));
    connectSocketData.sin_family = AF_INET;
    connectSocketData.sin_addr.s_addr = INADDR_ANY;
    connectSocketData.sin_port = htons(port);

    if(bind(s->connectSocket, (struct sockaddr*) &connectSocketData, sizeof(struct sockaddr_in)) != 0)
    {
        perror("Cannot bind socket");
        serverRemove(s);
        return -1;
    }
    
    // mark this socket as handler for connection requests
    if(listen(s->connectSocket, 5) != 0)
    {
        perror("Cannot start listening");
        serverRemove(s);
        return -1;
    }
    
    return 0;
}

void serverRemove(Server* s)
{
    s->port = -1;
    
    if(s->threads != NULL)
    {
        for(int i = 0; i < s->maxClients; i++)
        {
            if(s->threads[i] != -1)
            {
                printf("%d thread\n", i);
                pthread_cancel(s->threads[i]);
                pthread_join(s->threads[i], NULL);
            }
        }
        free(s->threads);
        s->threads = NULL;
    }
    
    if(s->clientSockets != NULL)
    {
        for(int i = 0; i < s->maxClients; i++)
        {
            if(s->clientSockets[i] != -1)
            {
                if(close(s->clientSockets[i]) == -1)
                {
                    printf("%d", i);
                    perror(" cannot close client socket");
                }
                else
                {
                    printf("%d closed\n", i);
                }
            }
        }
        free(s->clientSockets);
        s->clientSockets = NULL;
    }
    
    s->maxClients = -1;
    
    if(s->connectSocket != -1)
    {
        if(close(s->connectSocket) != 0)
        {
            perror("Cannot close server socket");
        }
        else
        {
            printf("connection listener closed\n");
        }
        s->connectSocket = -1;
    }
    
    s->hAmount = -1;
    s->hIndex = -1;
    if(s->handlers != NULL)
    {
        free(s->handlers);
        s->handlers = NULL;
    }
}

void* clientHandler(void* data)
{
    int id = ((ThreadData*) data)->id;
    Server* s = ((ThreadData*) data)->server;
    
    Stream in;
    while(strcmp(in.data, "quit") != 0)
    {
        int size = recv(s->clientSockets[id], in.data, BUFFER_SIZE - 1, 0);
        if(size > 0)
        {
            in.data[size] = '\0';
            int package = ((int) in.data[0]);
            if(package >= 0 && package < s->hIndex)
            {
                printf("Received package %d from %d: %s\n", package, id, in.data);
                in.index = 1;
                in.size = size;
                s->handlers[package](&in);
            }
            else
            {
                printf("Invalid package %d from %d\n", package, id);
            }
        }
        else if(size == 0)
        {
            printf("Client %d closed remote socket\n", id);
            break;
        }   
        else
        {
            perror("recv error");
            break;
        }
    }
    
    if(close(s->clientSockets[id]) != 0)
    {
        printf("%d", id);
        perror(" cannot close client socket");
    }
    else
    {
        printf("%d closed\n", id);
    }
    
    s->clientSockets[id] = -1;
    return NULL;
}

void serverWaitForConnection(Server* s)
{
    socklen_t addrlen = sizeof(struct sockaddr_in);
    char buffer[BUFFER_SIZE];
    
    while(1)
    {
        printf("Waiting for connections...\n");
        struct sockaddr_in clientSocketData;
        int clientSocket = accept(s->connectSocket, (struct sockaddr*) &clientSocketData, &addrlen);
        if(clientSocket >= 0)
        {
            printf("Client connected from %s:%d...\n", inet_ntoa(clientSocketData.sin_addr), (int) ntohs(clientSocketData.sin_port));
            
            int i = 0;
            while(1)
            {
                if(s->clientSockets[i] == -1)
                {
                    if(s->threads[i] != -1)
                    {
                        pthread_cancel(s->threads[i]);
                        pthread_join(s->threads[i], NULL);
                    }
                    
                    ThreadData data;
                    data.id = i;
                    data.server = s;
                    if(pthread_create(&s->threads[i], NULL, clientHandler, (void*) &data) != 0)
                    {
                        perror("Cannot create thread");  
                        
                        strcpy(buffer, "error: cannot create thread\n");
                        if(send(clientSocket, buffer, strlen(buffer), 0) == -1)
                        {
                            perror("Cannot send error");
                        }
                        close(clientSocket);
                    }
                    else
                    {
                        s->clientSockets[i] = clientSocket;
                        
                        strcpy(buffer, "Welcome to server, please enter your command:\n");
                        if(send(clientSocket, buffer, strlen(buffer), 0) == -1)
                        {
                            perror("Cannot send welcome message");
                            close(clientSocket);
                            s->clientSockets[i] = -1;
                        }
                    }
                    break;
                }
                
                i++;
                if(i >= s->maxClients)
                {
                    printf("max clients reached\n");    
                    
                    strcpy(buffer, "error: max clients reached\n");
                    if(send(clientSocket, buffer, strlen(buffer), 0) == -1)
                    {
                        perror("Cannot send error");
                    }
                    close(clientSocket);
                    break;
                }
            }
        }
    }
}

void serverRegisterHandler(Server* s, StreamFunction f)
{
    if(s->hAmount == s->hIndex)
    {
        if(s->hAmount == 0)
        {
            s->handlers = malloc(sizeof(StreamFunction));
            s->hAmount = 1;
        }
        else
        {
            s->hAmount *= 2;
            StreamFunction* functions = malloc(sizeof(StreamFunction) * s->hAmount);
            for(int i = 0; i < s->hIndex; i++)
            {
                functions[i] = s->handlers[i];
            }
            free(s->handlers);
            s->handlers = functions;
        }
    }
    s->handlers[s->hIndex] = f;
    s->hIndex++;
}