implement collecting all bits, if they don't come in one message

1 files changed, 831 insertions, 0 deletions

diff --git a/server.c b/server.c
new file mode 100644
index 0000000..837432a
--- /dev/null
+++ b/server.c
@@ -0,0 +1,831 @@
+#include <stdlib.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+#include <string.h>
+
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/types.h>
+
+#include "protocol.c"
+
+#define LINE_MAX 1024
+#define MAX_USERS 1000
+#define MAX_PATH 50
+
+typedef struct station {
+    int seekIndex;
+    char* filePath;
+} station_t;
+
+typedef struct user {
+    int udpPort;
+    int stationNum;
+    int sockfd;
+    pthread_t streamThread;
+} user_t;
+
+
+/* For safe condition variable usage, must use a boolean predicate and  */
+/* a mutex with the condition.                                          */
+int                 count = 0;
+pthread_cond_t      cond  = PTHREAD_COND_INITIALIZER;
+pthread_mutex_t     mutex = PTHREAD_MUTEX_INITIALIZER;
+
+pthread_mutex_t     station_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+const char *port;
+int num_stations;
+
+int start_threads = 0;
+int max_active_users = 0;
+
+pthread_mutex_t     mutex_user_data = PTHREAD_MUTEX_INITIALIZER;
+// array from index to user_data
+user_t  *user_data;
+int sockfd_to_user[MAX_USERS];
+
+// stations array pointer
+station_t *station_data;
+
+void *send_udp_packet_routine(void* arg);
+void *select_thread(void* arg);
+void *synchronization_thread(void* arg);
+
+int parse(char buffer[LINE_MAX], char *tokens[LINE_MAX / 2]);
+void *print_info_routine(void *arg);
+
+void *get_in_addr(struct sockaddr *sa);
+
+void *init_user(int sockfd);
+void *update_user_udpPort(int sockfd, int udpPort);
+void *update_user_station(int sockfd, int stationNum);
+void *print_user_data(int sockfd);
+void destroy_user(int sockfd);
+
+void send_announce_reply(int fd, int station_num);
+void send_invalid_command_reply(int fd, size_t message_size, char* message);
+
+// void *load_file(void* arg);
+
+int main(int argc, char *argv[])
+{
+    // threads to control reading files at chunks while the other threads sleep
+    // station_data = malloc(sizeof(station_t) * NUM_STATIONS);
+    // check and assign arguments
+    if (argc < 3) {
+        fprintf(stderr,"usage: ./snowcast_server <listen port> <file0> [file 1] [file 2] ... \n");
+        exit(1);
+    }
+
+    port = argv[1];
+    num_stations = argc - 2;
+
+    // printf("port: %s\n", port);
+    // printf("num_stations: %d\n", num_stations);
+
+    // init stations
+    size_t totalSize = 0;
+    // get size to malloc
+    for (int i = 2; i < argc; i++)
+    {
+        // printf("file: %s\n", argv[i]);
+        totalSize += sizeof(int) + strlen(argv[i]);
+    }
+    station_data = malloc(totalSize);
+    // assign the stations
+    for (int i = 2; i < argc; i++)
+    {
+        station_data[i - 2] = (station_t) { 0, argv[i]};
+    }
+
+    // print all indexes in station data
+    // for (int i = 0; i < num_stations; i++)
+    // {
+    //     printf("station %d: %s\n", i, station_data[i].filePath);
+    // }
+
+    // make array of user data
+    user_data = malloc(sizeof(user_t) * max_active_users);
+    if (!user_data) {  perror("malloc"); return 1; }
+
+    // make and start "select" thread that manages:
+    // 1) new connections, 2) requests from current connections, 3)cloing connections
+    pthread_t s_thread;
+    pthread_create(&s_thread, NULL, select_thread, NULL);
+
+    // start syncchronization thread to broadcast stations
+    pthread_t sync_thread;
+    pthread_create(&sync_thread, NULL, synchronization_thread, NULL);
+
+    // command line interface
+    char input[LINE_MAX];
+    memset(input, 0, LINE_MAX);
+
+    char *tokens[LINE_MAX / 2];
+    while (read(STDIN_FILENO, input, LINE_MAX) > 0) {
+        // init tokens
+        memset(tokens, 0, (LINE_MAX / 2) * sizeof(char *));
+
+        // if 0, all whitespace
+        if (!parse(input, tokens))
+            continue;
+
+        char *command = tokens[0];
+        // if q, shutdown!
+        if (!strcmp(command, "q")) {
+            printf("Exiting.\n");
+            // TODO: exit better than break
+            break;
+        }
+        
+        // if p, print info
+        else if (!strcmp(command, "p")) {
+            // get the file descriptor
+            int print_fd = 0;
+            // see if there is a file path
+            char *output_file_path = tokens[1];
+            if (output_file_path != NULL)
+            {
+                if ((print_fd = open(output_file_path, O_CREAT | O_WRONLY | O_TRUNC, S_IRWXU)) == -1)
+                {
+                    perror("open");
+                    continue;
+                }
+            } else {
+                print_fd = STDOUT_FILENO;
+            }
+            // printf("print_fd: %d\n", print_fd);
+            pthread_t print_info_thread;
+            pthread_create(&print_info_thread, NULL, print_info_routine, print_fd);
+            // note - this file descriptor is closed in the thread
+        }
+        else if (!strcmp(command, "u"))
+        {
+            // print all user data
+            for (int i = 0; i < max_active_users; i++)
+            {
+                print_user_data(i);
+            }
+        }
+    }
+
+    return 0;
+}
+
+void write_int_to_fd(int fd, int n) {
+    int l = snprintf(NULL, 0, "%d", n);
+    char *num = malloc(l + 1);
+    if (!num) { perror("malloc"); return; }
+
+    snprintf(num, l + 1, "%d", n);
+    if (write(fd, num, strlen(num)) == -1) {
+        perror("write");
+    }
+
+
+    free(num);
+}
+
+void *print_info_routine(void *arg) {
+    int print_fd = (int) arg;
+    // printf("thread print_fd: %d\n", print_fd);
+    // printf("num_stations: %d\n", num_stations);
+    for (int i = 0; i < num_stations; i++) {
+        write_int_to_fd(print_fd, i);
+        char *comma = ",";
+        write(print_fd, comma, strlen(comma));
+
+        // write file path
+        char* file_path = station_data[i].filePath;
+        write(print_fd, file_path, strlen(file_path));
+
+        for (int j = 0; j < max_active_users; j++) {
+            if (!user_data[j].sockfd || user_data[j].sockfd == -1)
+                continue;
+            if (user_data[j].stationNum == i) {
+                char *localhost_ip = ",127.0.0.1:";
+                write(print_fd, localhost_ip, strlen(localhost_ip));
+                // write udpPort
+                write_int_to_fd(print_fd, user_data[j].udpPort);
+            }
+        }
+        // wrtie new line
+        char *newline = "\n";
+        write(print_fd, newline, strlen(newline));
+    }
+
+    if (print_fd != STDOUT_FILENO) close(print_fd);
+    return (NULL);
+}
+
+int send_all_udp(int udp_sockfd, char *buf, int *len, struct addrinfo *thread_res)
+{
+    int MAX_PACKET_SIZE = 512;
+    int total = 0;        // how many bytes we've sent
+    int bytesleft = *len; // how many we have left to send
+    int n;
+
+    while(total < *len) {
+        n = sendto(udp_sockfd, buf+total, MAX_PACKET_SIZE, 0, thread_res->ai_addr, thread_res->ai_addrlen);
+        //         thread_res->ai_addr, thread_res->ai_addrlen)) == -1;
+        if (n == -1) { break; }
+        total += n;
+        bytesleft -= n;
+    }
+
+    *len = total; // return number actually sent here
+
+    return n==-1?-1:0; // return -1 on failure, 0 on success
+} 
+
+
+/* Make the manager routine */
+void *send_udp_packet_routine(void *arg) {
+    // unpack args
+    int user_index = (int) arg;
+    // printf("thread : user_index: %d\n", user_index);
+    // print user data
+    // print_user_data(user_index);
+
+    // declare vairables to be used
+    int did_work = 1;
+    pthread_mutex_t m = PTHREAD_MUTEX_INITIALIZER;
+    int s;
+    int udp_sockfd;
+    struct addrinfo thread_hints, *thread_res, *thread_servinfo;
+    int error_code;
+
+    // TODO: add error checking on these calls***
+
+    // setup hints
+    memset(&thread_hints, 0, sizeof thread_hints);
+    thread_hints.ai_family = AF_INET;  // use IPv4 only
+    thread_hints.ai_socktype = SOCK_DGRAM;
+    thread_hints.ai_flags = AI_PASSIVE; // fill in my IP for me
+
+    // setup the socket for client listener DATAGRAM (udp)
+    // cover the port integer to a string
+    int int_port = user_data[user_index].udpPort;
+    int length = snprintf( NULL, 0, "%d", int_port );
+    char* port = malloc( length + 1 );
+    if (!port) { perror("malloc"); return (NULL); }
+    snprintf( port, length + 1, "%d", int_port );
+    sprintf(port, "%d", int_port);
+
+    if (error_code = getaddrinfo(NULL, port, &thread_hints, &thread_servinfo) != 0)
+    {
+        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(error_code));
+        return (NULL);
+    }
+    free(port);
+
+    // loop through all the results and make a socket
+    for(thread_res = thread_servinfo; thread_res != NULL; thread_res = thread_res->ai_next) {
+        if ((udp_sockfd = socket(thread_res->ai_family, thread_res->ai_socktype,
+                thread_res->ai_protocol)) == -1) {
+            perror("talker: socket");
+            continue;
+        }
+        break;
+    }
+    if (udp_sockfd == NULL) {
+        fprintf(stderr, "talker: failed to create socket\n");
+        return (NULL);
+    }
+
+    // bind(udp_sockfd, thread_res->ai_addr, thread_res->ai_addrlen);
+
+
+    // freeaddrinfo(thread_servinfo);
+
+    while (1) {
+        // wait for 
+        pthread_mutex_lock(&m);
+        did_work = 0;
+        while (!start_threads)
+        {
+            pthread_cond_wait(&cond, &m);
+        }
+
+        int station_num = user_data[user_index].stationNum;
+        if (station_num == -1) {
+            did_work = 1;
+        }
+
+        if (!did_work) {
+            // sendto a random string of data to the user
+            int station_num = user_data[user_index].stationNum;
+            char *data = station_data[station_num].filePath;
+            // printf("load data: thread %d \n", user_index);
+
+            // get file path
+            char* file_path = station_data[station_num].filePath;
+            // get current seek chunk
+            int stream_fd = open(file_path, O_RDONLY);
+            if (stream_fd == -1) {
+                perror("open");
+                return (NULL);
+            }
+            int current_chunk = station_data[station_num].seekIndex;
+            if (lseek(stream_fd, current_chunk, SEEK_SET) == -1) {
+                perror("fseek");
+                return (NULL);
+            }
+            size_t BYTES_PER_SECOND = 16*1024;
+            // read 1000 bytes of the file
+            char file_buffer[BYTES_PER_SECOND];
+            if (read(stream_fd, file_buffer, BYTES_PER_SECOND) == -1) {
+                perror("fread");
+                return (NULL);
+            }
+            close(stream_fd);
+            // printf("send data: thread %d \n", user_index);
+            // int numbytes;
+            // if ((numbytes = sendto(udp_sockfd, data, strlen(data), 0,
+            //         thread_res->ai_addr, thread_res->ai_addrlen)) == -1) {
+            //     perror("talker: sendto");
+            //     return (NULL);
+            // }
+            // print the size of the file_buffer
+            // printf("size of file_buffer: %lu\n", sizeof(file_buffer));
+
+            int bytes_sent = sizeof(file_buffer);
+            if (send_all_udp(udp_sockfd, file_buffer, &bytes_sent, thread_res) == -1)
+            {
+                perror("send_all_udp");
+                printf("We only sent %d bytes because of the error!\n", bytes_sent);
+            }
+            // printf("We sent all %d bytes!\n", bytes_sent);
+
+            did_work = 1;
+
+
+            usleep(400000);
+        }
+
+        pthread_mutex_unlock(&m);
+
+        usleep(100000);
+    }
+    return NULL;
+}
+
+void *send_announce_routine(void *arg) {
+    // unpack args
+    int station_num = (int) arg;
+     // send the announce messages
+    for (int i = 0; i < max_active_users; i++)
+    {
+        // if (user_data[i].streamThread == NULL) {
+        //     break;
+        // }
+        if (user_data[i].sockfd == 0 || user_data[i].sockfd == -1) {
+            continue;
+        }
+        // print_user_data(i);
+        // update the station of each user
+        if (user_data[i].stationNum == station_num)
+        {
+            // printf("sending announce to user %d\n", i);
+            send_announce_reply(user_data[i].sockfd, station_num);
+        }
+    }
+}
+
+void *synchronization_thread(void *arg) {
+    int c = 0;
+    while (1)
+    {
+        start_threads = 1;
+        // printf("\nbroadcast %d\n", c++);
+        pthread_cond_broadcast(&cond);
+        usleep(2000);
+        start_threads = 0;
+        // printf("before loop");
+        // update file seek index for each station
+        size_t BYTES_PER_SECOND = 16*1024;
+        // print num_stations
+        // printf("num_stations: %d\n", num_stations);
+        for (int i = 0; i < num_stations; i++)
+        {
+            // printf("checking station %d\n", i);
+            // get size of file
+            struct stat f_info;
+            // int file_fd = open(station_data[i].filePath, O_RDONLY);
+            // if (file_fd == -1) {
+            //     perror("open");
+            //     return (NULL);
+            // }
+            if (stat(station_data[i].filePath, &f_info) == -1) {
+                perror("fstat");
+                return (NULL);
+            }
+
+            size_t size = f_info.st_size;
+
+            // fclose(file_fd);
+            // if (size == -1) {
+            //     perror("ftell");
+            //     return (NULL);
+            // }
+            station_data[i].seekIndex += BYTES_PER_SECOND;
+            // if the seek index is greater than the size of the file, reset it
+            if (station_data[i].seekIndex >= size)
+            {
+                station_data[i].seekIndex = 0;
+                // printf("resetting station %d\n", i);
+
+                pthread_t send_announce_thread;
+                pthread_create(&send_announce_thread, NULL, send_announce_routine, (void *)i);
+            }
+        }
+
+
+        usleep(2000);
+        usleep(1000000-4000);
+    }
+}
+
+void *select_thread(void *arg) {
+    fd_set master;    // master file descriptor list
+    fd_set read_fds;  // temp file descriptor list for select()
+    int fdmax;        // maximum file descriptor number
+
+    int listener;     // listening socket descriptor
+    int newfd;        // newly accept()ed socket descriptor
+    struct sockaddr_storage remoteaddr; // client address
+    socklen_t addrlen;
+
+    char buf[256];    // buffer for client data
+    int nbytes;
+
+
+    char remoteIP[INET6_ADDRSTRLEN];
+
+    int yes=1;        // for setsockopt() SO_REUSEADDR, below
+    int i, j, rv;
+
+    struct addrinfo hints, *ai, *p;
+
+    // const char* port = argv[1];
+
+    FD_ZERO(&master);    // clear the master and temp sets
+    FD_ZERO(&read_fds);
+
+    // LISTENER: get us a socket and bind it
+    memset(&hints, 0, sizeof hints);
+    hints.ai_family = AF_INET;
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_flags = AI_PASSIVE;
+    if ((rv = getaddrinfo(NULL, port, &hints, &ai)) != 0) {
+        fprintf(stderr, "snowcast_server: %s\n", gai_strerror(rv));
+        exit(1);
+    }
+
+    for(p = ai; p != NULL; p = p->ai_next) {
+        listener = socket(p->ai_family, p->ai_socktype, p->ai_protocol);
+        if (listener < 0) { 
+            continue;
+        }
+        
+        // lose the pesky "address already in use" error message
+        setsockopt(listener, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int));
+
+        if (bind(listener, p->ai_addr, p->ai_addrlen) < 0) {
+            close(listener);
+            continue;
+        }
+
+        break;
+    }
+
+    // if we got here, it means we didn't get bound
+    if (p == NULL) {
+        fprintf(stderr, "snowcast_server: failed to bind\n");
+        exit(2);
+    }
+
+    freeaddrinfo(ai); // all done with this
+
+     // listen
+    if (listen(listener, 10) == -1) {
+        perror("listen");
+        exit(3);
+    }
+
+    // add the listener to the master set
+    FD_SET(listener, &master);
+
+    // keep track of the biggest file descriptor
+    fdmax = listener; // so far, it's this one
+
+    while(1) {
+        read_fds = master; // copy it
+        if (select(fdmax+1, &read_fds, NULL, NULL, NULL) == -1) {
+            perror("select");
+            exit(4);
+        }
+
+        // run through the existing connections looking for data to read
+        for(i = 0; i <= fdmax; i++) {
+            if (FD_ISSET(i, &read_fds)) { // we got one!!
+                if (i == listener) {
+                    // handle new connections
+                    addrlen = sizeof remoteaddr;
+                    newfd = accept(listener,
+                        (struct sockaddr *)&remoteaddr,
+                        &addrlen);
+
+                    if (newfd == -1) {
+                        perror("accept");
+                    } else {
+                        FD_SET(newfd, &master); // add to master set
+                        if (newfd > fdmax) {    // keep track of the max
+                            fdmax = newfd;
+                        }
+                        // printf("selectserver: new connection from %s on "
+                        //     "socket %d\n.",
+                        //     inet_ntop(remoteaddr.ss_family,
+                        //         get_in_addr((struct sockaddr*)&remoteaddr),
+                        //         remoteIP, INET6_ADDRSTRLEN),
+                        //     newfd);
+                        // init user with this newfd
+                        init_user(newfd);
+                    }
+                } else {
+                    // handle data from a client
+                    struct Command command;
+                    if ((nbytes = recv(i, (char*)&command, sizeof(struct Command), 0)) <= 0) {
+                        // got error or connection closed by client
+                        if (nbytes == 0) {
+                            // connection closed
+                            // printf("selectserver: socket %d hung up\n", i);
+                        } else {
+                            perror("recv");
+                        }
+                        close(i); // bye!
+                        FD_CLR(i, &master); // remove from master set
+                        // remove user from data structures
+                        destroy_user(i);
+                    } else {
+                        // we got some data from a client
+                        if (command.commandType == 0) {
+                            // hello message with udpPort
+                            // printf("udpPort (from Hello) for new connection is %d.\n", ntohs(command.number));
+                            // update udp port of user
+                            update_user_udpPort(i, ntohs(command.number));
+
+                            // send the welcome message to client
+                            struct Welcome welcome;
+                            welcome.replyType = 2;
+                            welcome.numStations = htons(num_stations);
+                            int bytes_to_send = sizeof(struct Welcome);
+                            if (send_all(i, &welcome, &bytes_to_send) == -1)
+                                perror("send_all");
+                        }
+                        else if (command.commandType == 1) {
+                            // check if user has a udpPort
+                            if (user_data[sockfd_to_user[i]].udpPort == -1) {
+                                // send back in invalid command
+                                char * message = "Must send Hello message first.";
+                                send_invalid_command_reply(i, strlen(message), message);
+                                // drop connection upon invalid command
+                                close(i);
+                                FD_CLR(i, &master);
+                                destroy_user(i);
+                                continue;
+                            }
+
+                            int station_num = ntohs(command.number);
+                            // printf("station_num: %d\n", station_num);
+                            if (station_num >= num_stations || station_num < 0) {
+                                // send back in invalid command
+                                char * message = "Station number out of range.";
+                                send_invalid_command_reply(i, strlen(message), message);
+                                // drop connection upon invalid command
+                                close(i);
+                                FD_CLR(i, &master);
+                                destroy_user(i);
+                                continue;
+                            }
+
+                            // printf("setting station to %d\n", ntohs(command.number));
+                            // update station of user
+                            update_user_station(i, ntohs(command.number));
+                            send_announce_reply(i, station_num);
+                        }
+                        else {
+                            // send back in invalid command
+                            char * message = "Invalid command";
+                            send_invalid_command_reply(i, strlen(message), message);
+                            
+                            // drop connection upon invalid command
+                            close(i);
+                            FD_CLR(i, &master);
+                            destroy_user(i);
+                        }
+                    }
+                } // END handle data from client
+            } // END got new incoming connection
+        } // END looping through file descriptors
+
+    } // END for(;;)--and you thought it would never end!
+}
+
+void *init_user(int sockfd) {
+    // add the user to the list of user data
+    pthread_mutex_lock(&mutex_user_data);
+    // this is to save memory space. 
+    // in general, the displacement of 4 is where a user "used to be"
+    // int user_index = max_active_users++;
+    // int running_index = 0;
+    // while(running_index < max_active_users)
+    // {
+    //     if (user_data[running_index++].sockfd == -1)
+    //     {
+    //         user_index = running_index;
+    //         break;
+    //     }
+    //     // printf("reusing memory\n");
+    // }
+    int running_index = 0;
+    while(running_index < max_active_users) {
+        if (user_data[running_index].sockfd == -1) {
+            break;
+        }
+        running_index++;
+    }
+    if (running_index == max_active_users) {
+        // printf("reached max active users\n");
+        // printf("making new memory\n");
+        max_active_users++;
+        // TODO: FIX SO THAT IT USES CURRENT USERS, NOT MAX_ACTIVE_USERS FOT THE RESIZE
+        user_t *more_users = realloc(user_data, sizeof(user_t) * max_active_users);
+        if (!more_users) { perror("realloc"); exit(1); }
+        user_data = more_users;
+    }
+    
+
+    // map TCP sockfd to this user index
+    user_data[running_index] = (user_t){-1, -1, sockfd, -1};
+    sockfd_to_user[sockfd] = running_index;
+    // free(user_stream_threads);
+    pthread_mutex_unlock(&mutex_user_data);
+}
+void *update_user_udpPort(int sockfd, int udpPort) {
+    pthread_mutex_lock(&mutex_user_data);
+    // get the user
+    user_t *user = &user_data[sockfd_to_user[sockfd]];
+    // set the udpPort
+    user->udpPort = udpPort;
+    // start the stream thread, now that we have the udpPort
+    pthread_create(&user->streamThread, NULL, send_udp_packet_routine, (void *)sockfd_to_user[sockfd]);
+    pthread_mutex_unlock(&mutex_user_data);
+}
+void *update_user_station(int sockfd, int stationNum) {
+    pthread_mutex_lock(&mutex_user_data);
+    user_data[sockfd_to_user[sockfd]].stationNum = stationNum;
+    pthread_mutex_unlock(&mutex_user_data);
+}
+void *print_user_data(int index) {
+    printf("udpPort: %d, stationNum: %d, sockfd: %d, threadId:%d\n", 
+        user_data[index].udpPort, user_data[index].stationNum, user_data[index].sockfd, user_data[index].streamThread);
+}
+
+void destroy_user(int sockfd) {
+    pthread_mutex_lock(&mutex_user_data);
+    // stop the thread streaming to the user
+    // TODO: close the FD in the stream thread
+    pthread_cancel(user_data[sockfd_to_user[sockfd]].streamThread);
+    // close(user_data[sockfd_to_user[sockfd]].udpPort);
+    // pthread_kill(user_data[sockfd_to_user[sockfd]].streamThread, SIGINT);
+    // "remove" the user from the list of user data
+    user_data[sockfd_to_user[sockfd]] = (user_t) {-1, -1, -1, -1};
+    // map sockfd to -1
+    sockfd_to_user[sockfd] = -1;
+    // close(sockfd);
+
+    pthread_mutex_unlock(&mutex_user_data);
+}
+
+
+void *get_in_addr(struct sockaddr *sa)
+{
+    if (sa->sa_family == AF_INET) {
+        return &(((struct sockaddr_in*)sa)->sin_addr);
+    }
+
+    return &(((struct sockaddr_in6*)sa)->sin6_addr);
+}
+
+void send_announce_reply(int fd, int station_num) {
+    char* file_path = station_data[station_num].filePath;
+    int len_file_path = strlen(file_path);
+
+    char *send_buffer = malloc(len_file_path+2);
+    if (!send_buffer) {
+        perror("malloc");
+        return;
+    }
+    send_buffer[0] = 3;
+    send_buffer[1] = len_file_path;
+
+    memcpy(send_buffer + 2, file_path, len_file_path);
+
+    // printf("buffer: %s\n", send_buffer);
+
+    size_t bytes_to_send = len_file_path + 2;
+    if (send_all(fd, send_buffer, &bytes_to_send) == -1)
+        perror("send_all");
+    // print the number of bytes sent
+    // printf("sent %d bytes\n", bytes_to_send);
+
+    free(send_buffer);
+}
+
+void send_invalid_command_reply(int fd, size_t message_size, char* message) {
+    char *send_buffer = malloc(message_size+2);
+    if (!send_buffer) {
+        perror("malloc");
+        return;
+    }
+
+    // type and payload size
+    send_buffer[0] = 4;
+    send_buffer[1] = message_size;
+
+    memcpy(send_buffer + 2, message, message_size);
+
+    // printf("buffer: %s\n", send_buffer);
+
+    int bytes_to_send = message_size + 2;
+    if (send_all(fd, send_buffer, &bytes_to_send) == -1)
+        perror("send");
+    // print the number of bytes sent
+    // printf("sent %d bytes\n", bytessent);
+
+    free(send_buffer);
+}
+
+
+// Parses a buffer into tokens, from cs33 :)
+int parse(char buffer[LINE_MAX], char *tokens[LINE_MAX / 2]) {
+    const char *regex = " \n\t\f\r";
+    char *current_token = strtok(buffer, regex);
+    if (current_token == NULL) return 0;
+
+    for (int i = 0; current_token != NULL; i++) {
+        tokens[i] = current_token;
+        current_token = strtok(NULL, regex);
+    }
+
+    return 1;
+}
+
+// int send_all(int s, char *buf, int *len)
+// {
+//     int total = 0;        // how many bytes we've sent
+//     int bytesleft = *len; // how many we have left to send
+//     int n;
+
+//     while(total < *len) {
+//         n = send(s, buf+total, bytesleft, 0);
+//         if (n == -1) { break; }
+//         total += n;
+//         bytesleft -= n;
+//     }
+
+//     *len = total; // return number actually sent here
+
+//     return n==-1?-1:0; // return -1 on failure, 0 on success
+// } 
+
+// int recv_all(int sock, char *buffer, int total_size)
+// {
+//     int total_bytes_read = 0;
+//     int to_read = total_size;
+
+//     char *ptr = buffer;
+
+//     while (to_read > 0) {
+// 	int bytes_read = recv(sock, ptr, to_read, 0);
+// 	if (bytes_read <= 0) {
+// 	    if (bytes_read != 0) {
+// 		perror("recv");
+// 	    }
+// 	    return -1;
+// 	}
+
+// 	to_read -= bytes_read;
+// 	ptr += bytes_read;
+// 	total_bytes_read += bytes_read;
+//     }
+
+//     return total_bytes_read;
+// }