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 <signal.h>  
#include "SocketUtils.h"

void serverInitDefaults(Server* s)
{
    s->maxClients = -1;
    s->port = -1;
    s->threads = NULL;
    s->clientSockets = NULL;
    s->clientUser = NULL;
    s->connectSocket = -1;
    
    s->handler = NULL;
    
    s->directory = NULL;
}

int serverInit(Server* s, int maxClients, short port, char* directory)
{
    s->maxClients = maxClients;
    s->port = port;
    s->directory = directory;
    
    if(chdir(directory) == -1)
    {
        perror("cannot change directory");
        serverRemove(s);
        return -1;
    }
    
    // initialize storage for clients
    s->threads = malloc(sizeof(pthread_t) * maxClients);
    s->clientSockets = malloc(sizeof(int) * maxClients);
    s->clientUser = malloc(sizeof(char*) * maxClients);
    
    for(int i = 0; i < maxClients; i++)
    {
        s->threads[i] = -1;
        s->clientSockets[i] = -1;
        s->clientUser[i] = NULL;
    }
    
    // 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;
    }
    
    if(s->clientUser != NULL)
    {
        for(int i = 0; i < s->maxClients; i++)
        {
            if(s->clientUser[i] != NULL)
            {
                free(s->clientUser[i]);
                s->clientUser[i] = NULL;
            }
        }
        free(s->clientUser);
        s->clientUser = 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->handler = NULL;
}

static void* clientHandler(void* data)
{
    int id = ((ThreadData*) data)->id;
    Server* s = ((ThreadData*) data)->server;
    
    Stream in;
    while(1)
    {
        streamInit(&in, 1024);
        int size = receiveAll(s->clientSockets[id], &in);
        if(size > 0)
        {
            if(s->handler(id, s->clientSockets[id], &in))
            {
                break;
            }
        }
        else if(size == 0)
        {
            printf("Client %d closed remote socket\n", id);
            streamRemove(&in);
            break;
        }   
        else
        {
            perror("recv error");
            streamRemove(&in);
            break;
        }
        streamRemove(&in);
    }
    
    if(close(s->clientSockets[id]) != 0)
    {
        printf("%d", id);
        perror(" cannot close client socket");
    }
    else
    {
        printf("%d closed\n", id);
    }
    
    serverFreeUser(s, id);
    s->clientSockets[id] = -1;
    return NULL;
}

int serverSend(int clientSocket, Stream* out)
{
    if(sendAll(clientSocket, out) == -1)
    {
        return -1;
    }
    return 0;
}

void serverWaitForConnection(Server* s)
{
    socklen_t addrlen = sizeof(struct sockaddr_in);
    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");  
                        
                        Stream out;
                        streamInit(&out, 16);
                        streamWriteChar(&out, -1);
                        streamWriteChars(&out, "Cannot create thread\n");
                        serverSend(clientSocket, &out);
                        streamRemove(&out);
                        close(clientSocket);
                    }
                    else
                    {
                        s->clientSockets[i] = clientSocket;
                        
                        Stream out;
                        streamInit(&out, 64);
                        streamWriteChar(&out, 1);
                        streamWriteChars(&out, "Welcome to the server, please enter one of these commands:\n");
                        streamWriteChars(&out, "- HELP\n");
                        streamWriteChars(&out, "- SEND\n");
                        streamWriteChars(&out, "- LIST\n");
                        streamWriteChars(&out, "- READ\n");
                        streamWriteChars(&out, "- DEL\n");
                        streamWriteChars(&out, "- QUIT\n");
                        if(serverSend(clientSocket, &out) == -1)
                        {
                            perror("Cannot send welcome message");
                            close(clientSocket);
                            s->clientSockets[i] = -1;
                        }
                        streamRemove(&out);
                    }
                    break;
                }
                
                i++;
                if(i >= s->maxClients)
                {
                    printf("max clients reached\n");    
                    
                    Stream out;
                    streamInit(&out, 16);
                    streamWriteChar(&out, -1);
                    streamWriteChars(&out, "the server is full\n");
                    serverSend(clientSocket, &out);
                    streamRemove(&out);
                    close(clientSocket);
                    break;
                }
            }
        }
    }
}

void serverRegisterHandler(Server* s, ServerStreamFunction f)
{
    s->handler = f;
}

int serverSetUser(Server* s, int clientId, char* name)
{
    if(clientId < 0 || clientId >= s->maxClients)
    {
        return -1;
    }
    int l = strlen(name) + 1;
    s->clientUser[clientId] = malloc(sizeof(char) * l);
    strncpy(s->clientUser[clientId], name, l);
    return 0;
}

char* serverGetUser(Server* s, int clientId)
{
    if(clientId < 0 || clientId >= s->maxClients)
    {
        return NULL;
    }
    return s->clientUser[clientId];
}

void serverFreeUser(Server* s, int clientId)
{
    if(clientId < 0 || clientId >= s->maxClients)
    {
        return;
    }
    if(s->clientUser[clientId] != NULL)
    {
        free(s->clientUser[clientId]);
        s->clientUser[clientId] = NULL;
    }
}