gem-graph-server/src/server.c

//=-------------------------------------------------------------------------=//
//  Server management module                                                 //
//                                                                           //
//  Copyright © 2021 The Gem-graph Project                                   //
//                                                                           //
//  This file is part of gem-graph.                                          //
//                                                                           //
//  This program is free software: you can redistribute it and/or modify     //
//  it under the terms of the GNU Affero General Public License as           //
//  published by the Free Software Foundation, either version 3 of the       //
//  License, or (at your option) any later version.                          //
//                                                                           //
//  This program is distributed in the hope that it will be useful,          //
//  but WITHOUT ANY WARRANTY; without even the implied warranty of           //
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            //
//  GNU Affero General Public License for more details.                      //
//                                                                           //
//  You should have received a copy of the GNU Affero General Public License //
//  along with this program.  If not, see <https://www.gnu.org/licenses/>.   //
//=-------------------------------------------------------------------------=//

#include "../include/base.h"
#include "../include/cmds.h"

#include <netdb.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <errno.h>

static void *serverMain(void *server);

/* -------------------------------------------------------------------------- */

// -------------------------------------------------------------------------- //
// Server init function                                                       //
// -------------------------------------------------------------------------- //
void ServerInit(Server_t *server)
{
    pthread_create(&server->id, NULL, serverMain, server);
}

#define SEND_BUFFER_SIZE 80 * 24
#define RECEIVE_BUFFER_SIZE 80
void *serverCommunicationInstance(void *server)
{
    ServerCommunication_t *args;
    char **argv = NULL;
    char receiveBuff[RECEIVE_BUFFER_SIZE];
    char sendBuff[SEND_BUFFER_SIZE];
    int tokenIndex, bytesReceived;
    char clientIP[16];

    args = (ServerCommunication_t*) server;

    //Accept and incoming connection
    while(!args->pleaseStop) {

        // Zeroing buffer
        bzero(receiveBuff, RECEIVE_BUFFER_SIZE);
        printLog("Waiting for commands...\n");

        // Read the message from client and copy it in buffer
        bytesReceived = recv(args->sockfd, receiveBuff, RECEIVE_BUFFER_SIZE, 0);
        if (bytesReceived == -1) {
            printLog("Could not receive data!\n");
            break;
        };

        // Ignore null-sized request
        if (bytesReceived == 0)
            break;

        // Get ip address from client
        inet_ntop(AF_INET,
                &args->clientAddr.sin_addr,
                clientIP,
                args->socklen);

        // Print buffer which contains the client request
        printLog("Client %s:%d request : '%s'\n",
                 clientIP,
                 ntohs(args->clientAddr.sin_port),
                 receiveBuff);

        // get args in an array
        tokenIndex = 0;
        argv = (char**) realloc(argv, 1 * sizeof(char*));
        argv[0] = strtok(receiveBuff, " ");
        while (argv[tokenIndex]) {
            tokenIndex++;
            argv = (char**) realloc(argv, (tokenIndex+1) * sizeof(char*));
            argv[tokenIndex] = strtok(NULL, " ");
        }

        // Zeroing buffer
        bzero(sendBuff, RECEIVE_BUFFER_SIZE);

        // Execute command by first arg in cmdList
        for (int i = 0; i < LEN(cmdList); i++) {
            if (strcmp(cmdList[i].name, argv[0]) == 0) {
                cmdList[i].execute(sendBuff, argv, args->parent);
            }
        }

        // and send that buffer to client
        send(args->sockfd, sendBuff, SEND_BUFFER_SIZE, 0);
    }

    close(args->sockfd);
    if (argv)
        free(argv);
    printLog("Disconnected from\n");
    return NULL;
}

// -------------------------------------------------------------------------- //
// Server main function                                                       //
// -------------------------------------------------------------------------- //
#define PORT 9000
#define MAX_CONNECTION 100

static void *serverMain(void *server)
{
    Server_t *args;
    ServerCommunication_t serverSlots[MAX_CONNECTION] = {0};
    int connfd, flags, threadStatus, serverSlotIndex = 0;
    uint socklen;
    struct sockaddr_in servaddr;
    char clientIP[16];

     // Get args
    args = (Server_t*) server;
    args->returnValue = 0;
    printLog("Server #%lu online\n", args->id);

    // Create socket
    args->sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (args->sockfd == -1) {
        printLog("Socket creation failed!\n");
        args->returnValue = 1;
        goto serverExiting;
    }

    // Get socket flags
    flags = fcntl(args->sockfd, F_GETFL);
    if (flags == -1) {
        printLog("Socket parameters getting failed!\n");
        args->returnValue = 1;
        goto serverExiting;
    }

    // Change socket flags to non-blocking
    if (fcntl(args->sockfd, F_SETFL, flags | O_NONBLOCK) < 0) {
        printLog("Socket non-blocking setting failed!\n");
        args->returnValue = 1;
        goto serverExiting;
    }

    // Prepare binding structure
    bzero(&servaddr, sizeof(servaddr));

    // Assign IP and PORT
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(PORT);

    // Binding newly created socket
    if ((bind(args->sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr))) == -1) {
        printLog("Socket bind failed!\n");
        args->returnValue = 1;
        goto serverExiting;
    }

    // Now server is ready to listen and verification
    if (listen(args->sockfd, MAX_CONNECTION) == -1) {
        printLog("Socket listening failed!\n");
        args->returnValue = 1;
        goto serverExiting;
    }

    socklen = sizeof(struct sockaddr_in);

    if (getsockname(args->sockfd, (struct sockaddr *) &servaddr, &socklen)
            == -1) {
        printLog("Could not get sock name!\n");
        args->returnValue = 1;
        goto serverExiting;
    }

    printLog("Server listening...\n");

    while (!args->pleaseStop) {

        // Accept the data packet from client
        connfd = accept(args->sockfd,
                    (struct sockaddr*) &serverSlots[serverSlotIndex].clientAddr,
                    &socklen);
        if (connfd < 0) {
            // If error is not due to lack of clients connecting, this is error
            if (errno != EWOULDBLOCK && errno != EAGAIN) {
                printLog("Server acccept failed!\n");
                goto serverExiting;
            }
            sleep(1);
        } else {
            // Client connected
            // get IP addr from client
            inet_ntop(AF_INET,
                      &(serverSlots[serverSlotIndex].clientAddr.sin_addr),
                      clientIP, socklen);
            printLog("Client accepted from %s:%d\n",
                     clientIP,
                     ntohs(serverSlots[serverSlotIndex].clientAddr.sin_port));

            // Populate communicator slot
            serverSlots[serverSlotIndex].socklen = socklen;
            serverSlots[serverSlotIndex].sockfd = connfd;
            serverSlots[serverSlotIndex].parent = args;

            // Create thread
            threadStatus = pthread_create(&serverSlots[serverSlotIndex].id,
                           NULL,
                           serverCommunicationInstance,
                           (void*)&serverSlots[serverSlotIndex]);
            if(threadStatus != 0) {
                printLog("Error from pthread: %d\n", threadStatus);
                args->returnValue = 1;
                goto serverExiting;
            }

            serverSlotIndex++;
            printLog("Accepted connection. Server will now listen...\n");
        }
    }

serverExiting:
    close(args->sockfd);
    printLog("Server #%lu offline\n", args->id);
    return NULL;
}