merge post-warmup with main

1 files changed, 855 insertions, 100 deletions

diff --git a/server.c b/server.c
index bc36589..c889093 100644
--- a/server.c
+++ b/server.c
@@ -1,154 +1,909 @@
-/*
-** server.c -- a stream socket server demo
-*/
-
-#include <stdio.h>
 #include <stdlib.h>
-#include <stdint.h>
+#include <pthread.h>
+#include <stdio.h>
 #include <unistd.h>
-#include <errno.h>
-#include <string.h>
-#include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
-#include <netdb.h>
 #include <arpa/inet.h>
-#include <sys/wait.h>
-#include <signal.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
+#define MAX_RATE_PER_SECOND 16*1024 / 2
+
+// typedef struct station {
+//     int streamFd;
+//     char* filePath;
+//     int fileBufferSize;
+//     char fileBuffer[MAX_STREAM_RATE];
+// } station_t;
+typedef struct station {
+    pthread_t streamThread;
+    int readfd;
+    char *filePath;
+} station_t;
+int num_stations;
+station_t *stations;
+int setup_stations(int argc, char *argv[]);
+void *stream_routine(void *arg);
+
+
+typedef struct user {
+    int udpPort;
+    int stationNum;
+    int sockfd;
+} 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;
+int max_sockfd = 0;
+
+pthread_mutex_t     mutex_user_data = PTHREAD_MUTEX_INITIALIZER;
+// array from index to user_data
+user_t  *user_data;
+int *sockfd_to_user;
+
+// stations array pointer
+// station_t *station_data;
+
+struct udp_packet_routine_args {
+    int user_index;
+    int buffer_size;
+    char *file_buffer;
+};
+
+void *send_udp_packet_routine(void* arg);
+void *select_routine(void* arg);
+void *sync_routine(void* arg);
+void *send_announce_routine(void* arg);
+
+void init_station(int station_num, const char *station_name);
+
+int parse(char buffer[LINE_MAX], char *tokens[LINE_MAX / 2]);
+void *print_info_routine(void *arg);
 
-#include "protocol.h"
+void *get_in_addr(struct sockaddr *sa);
 
-#define BACKLOG 10   // how many pending connections queue will hold
+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);
 
-#define MAXDATASIZE 100 // max number of bytes we can get at once 
+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);
 
-void sigchld_handler(int s)
+main(int argc, char *argv[])
 {
-    // waitpid() might overwrite errno, so we save and restore it:
-    int saved_errno = errno;
+    // check and assign arguments
+    if (argc < 3) {
+        fprintf(stderr,"usage: ./snowcast_server <listen port> <file0> [file 1] [file 2] ... \n");
+        exit(1);
+    }
+
+    // initizlize the port
+    port = argv[1];
+
+    // initialize the stations & their threads
+    if (setup_stations(argc, argv) == -1) {
+        perror("setup_stations");
+        exit(1);
+    }
+
+    // make array of user data
+    printf("max active users: %d\n", sizeof(user_t) * max_active_users);
+    user_data = malloc(sizeof(user_t) * max_active_users);
+    if (!user_data) {  perror("malloc userdata"); return 1; }
+    sockfd_to_user = malloc(sizeof(int) * max_active_users);
+    if (!sockfd_to_user) {  perror("malloc sockfd to user"); return 1; }
+
+    // make and start "select" thread that manages:
+    // 1) new connections, 2) requests from current connections, 3) closing connections
+    pthread_t select_thread;
+    pthread_create(&select_thread, NULL, select_routine, NULL);
+
+    // start syncchronization thread to broadcast stations
+    // pthread_t sync_thread;
+    // pthread_create(&sync_thread, NULL, sync_routine, 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;
 
-    while(waitpid(-1, NULL, WNOHANG) > 0);
+        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);
+            }
+        }
+    }
 
-    errno = saved_errno;
+    return 0;
 }
 
+int read_file(int fd, char buffer[MAX_RATE_PER_SECOND], int station_num) {
+    int bytes_read = read(fd, buffer, MAX_RATE_PER_SECOND);
+    if (bytes_read < 0) { perror("read (from station file)"); return -1; }
+    // printf("bytes read: %d\n", bytes_read);
+    if (bytes_read == 0) {
+        // printf("end of file, restarting\n");
+        pthread_t send_announce_thread;
+        pthread_create(&send_announce_thread, NULL, send_announce_routine, station_num);
 
-// get sockaddr, IPv4 or IPv6:
-void *get_in_addr(struct sockaddr *sa)
-{
-    if (sa->sa_family == AF_INET) {
-        return &(((struct sockaddr_in*)sa)->sin_addr);
+        if (lseek(fd, 0, SEEK_SET) == -1)
+        {
+            perror("lseek (in resarting file)");
+            return -1;
+        }
+        bytes_read = read(fd, buffer, MAX_RATE_PER_SECOND);
+        if (bytes_read < 0) { perror("read (from station file, after restart)"); return -1; }
     }
 
-    return &(((struct sockaddr_in6*)sa)->sin6_addr);
+    return bytes_read;
+}
+
+void *stream_routine_cleanup(void *arg) {
+    int read_fd = (int) arg;
+    close(read_fd);
+}
+
+void *stream_routine(void *arg) {
+    int station_num = (int) arg;
+    printf("stream routine %d\n", station_num);
+    int read_fd = stations[station_num].readfd;
+
+    pthread_cleanup_push(stream_routine_cleanup, read_fd);
+
+    // make buffer which will be used to stream to children
+    char buffer[MAX_RATE_PER_SECOND];
+    memset(buffer, 0, MAX_RATE_PER_SECOND);
+    // if (!buffer) { perror("malloc (buffer in station thread)"); exit(1); }
+
+    for (;;)
+    {
+        // load bytes into buffer
+        int bytes_read = read_file(read_fd, buffer, station_num);
+        if (bytes_read == -1) { exit(1); }
+
+        // TODO: send buffer to children
+        char *send_buffer = malloc(2 + bytes_read);
+        for (int i = 0; i < max_active_users; i++)
+        {
+            if (!user_data[i].sockfd || user_data[i].sockfd == -1)
+                continue;
+            if (user_data[i].stationNum == station_num)
+            {
+                // send the udp packet
+                int *send_buffer = malloc(2 + bytes_read);
+                memset(send_buffer, 0, 2 + bytes_read);
+                send_buffer[0] = i;
+                send_buffer[1] = bytes_read;
+                memcpy(send_buffer+2, buffer, bytes_read);
+                // printf("sending udp packet to user %d\n", i);
+                pthread_t t;
+                pthread_create(&t, NULL, send_udp_packet_routine, send_buffer);
+            }
+        }
+        free(send_buffer);
+        usleep(1000000 / 2 - 5000);
+        start_threads = 1;
+        pthread_cond_broadcast(&cond);
+
+        usleep(5000);
+        start_threads = 0;
+
+        memset(buffer, 0, MAX_RATE_PER_SECOND);
+    }
+
+    return (NULL);
+
+    pthread_cleanup_pop(1);
 }
 
-int main(int argc, char *argv[])
+int setup_stations(int argc, char *argv[]) {
+    num_stations = argc - 2;
+
+    // get the size to malloc
+    int totalSize = 0;
+    for(int i = 2; i < argc; i++)
+    {
+        totalSize += sizeof(pthread_t) + sizeof(int)  + strlen(argv[i]);
+    }
+
+    // malloc the stations array
+    stations = malloc(totalSize);
+    if (!stations) { perror("malloc (stations pointer)"); return -1; }
+    // assign the stations, and start the threads
+    for (int i = 0; i < num_stations; i++) {
+        stations[i].filePath = argv[i+2];
+        stations[i].readfd = open(argv[i+2], O_RDONLY);
+        if (stations[i].readfd < 0) { perror("read (from station file)"); return -1; }
+        pthread_create(&stations[i].streamThread, NULL, stream_routine, i);
+    }
+
+    printf("successfully created %d stations\n", num_stations);
+    return 1;
+}
+
+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 write to fd"); 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 = stations[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 sockfd, new_fd, numbytes, b;  // listen on sock_fd, new connection on new_fd
-    char buf[MAXDATASIZE];
-    struct addrinfo hints, *servinfo, *p;
-    struct sockaddr_storage their_addr; // connector's address information
-    socklen_t sin_size;
-    struct sigaction sa;
-    int yes=1;
-    char s[INET6_ADDRSTRLEN];
-    int rv;
+    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;
 
-    if (argc < 3) {
-        fprintf(stderr,"usage: <listen port> <file0> [file 1] [file 2] ... \n");
-        exit(1);
+    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;
     }
 
-    memset(&hints, 0, sizeof hints);
-    hints.ai_family = AF_INET; // only IPv4
-    hints.ai_socktype = SOCK_STREAM; // TCP connection
-    hints.ai_flags = AI_PASSIVE; // use my IP
+    *len = total; // return number actually sent here
+
+    return n==-1?-1:0; // return -1 on failure, 0 on success
+} 
+
+void udp_port_cleanup_handler(void *arg)
+{
+    int sockfd = (int) arg;
+    close(sockfd);
+}
+
+/* Make the manager routine */
+void *send_udp_packet_routine(void *arg) {
+    // printf("send udp packet routine\n");
+    int *buf =  arg;
+    // unpack args
+    int user_index = buf[0];
+    int buffer_size = buf[1];
+    char *file_buffer = malloc(buffer_size);
+    memcpy(file_buffer, buf+2, buffer_size);
+
+    // printf("udp packet routine, user:%d\n size: %d\n", user_index, buffer_size);
+
+    // 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;
+
+    // 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
+
+    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 on port"); 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);
+    }
 
-    const char* port = argv[1];  // the port users will be connecting to
+    pthread_cleanup_push(udp_port_cleanup_handler, (void *)udp_sockfd);
+        // wait for 
+    pthread_mutex_lock(&m);
+    did_work = 0;
+    while (!start_threads)
+    {
+        pthread_cond_wait(&cond, &m);
+    }
 
-    if ((rv = getaddrinfo(NULL, port, &hints, &servinfo)) != 0) {
-        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
-        return 1;
+    int station_num = user_data[user_index].stationNum;
+    if (station_num == -1) {
+        did_work = 1;
     }
+    // potential error here!
+    // printf("station info - bytes read: %d, station_fd: %d, filePath: %s, buffersize: %d\n", bytes_read, station_info->streamFd, station_info->filePath, station_info->fileBufferSize);
+
+    if (send_all_udp(udp_sockfd, file_buffer, &buffer_size, thread_res) == -1)
+    {
+        perror("send_all_udp");
+        printf("We only sent %d bytes because of the error!\n", buffer_size);
+    }
+
+    free(file_buffer);
+
+    pthread_mutex_unlock(&m);
+
+    pthread_cleanup_pop(1);
+
+    return (NULL);
+}
 
-    // loop through all the results and bind to the first we can
-    for(p = servinfo; p != NULL; p = p->ai_next) {
-        if ((sockfd = socket(p->ai_family, p->ai_socktype,
-                p->ai_protocol)) == -1) {
-            perror("server: socket");
+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].sockfd == 0 || user_data[i].sockfd == -1) {
             continue;
         }
+        // update the station of each user
+        if (user_data[i].stationNum == station_num)
+        {
+            send_announce_reply(user_data[i].sockfd, station_num);
+        }
+    }
+}
+
+// void *sync_routine(void *arg) {
+//     int c = 0;
+//     while (1)
+//     {
+//         start_threads = 1;
+//         pthread_cond_broadcast(&cond);
+//         usleep(2000);
+
+//         start_threads = 0;
+
+//         usleep(1000000-2000);
+//     }
+// }
+
+void *select_routine(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;
 
-        if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes,
-                sizeof(int)) == -1) {
-            perror("setsockopt");
-            exit(1);
+    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(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
-            close(sockfd);
-            perror("server: bind");
+        if (bind(listener, p->ai_addr, p->ai_addrlen) < 0) {
+            close(listener);
             continue;
         }
 
         break;
     }
 
-    freeaddrinfo(servinfo); // all done with this structure
-
-    if (p == NULL)  {
-        fprintf(stderr, "server: failed to bind\n");
-        exit(1);
+    // if we got here, it means we didn't get bound
+    if (p == NULL) {
+        fprintf(stderr, "snowcast_server: failed to bind\n");
+        exit(2);
     }
 
-    if (listen(sockfd, BACKLOG) == -1) {
+    freeaddrinfo(ai); // all done with this
+
+     // listen
+    if (listen(listener, 10) == -1) {
         perror("listen");
-        exit(1);
+        exit(3);
     }
 
-    sa.sa_handler = sigchld_handler; // reap all dead processes
-    sigemptyset(&sa.sa_mask);
-    sa.sa_flags = SA_RESTART;
-    if (sigaction(SIGCHLD, &sa, NULL) == -1) {
-        perror("sigaction");
-        exit(1);
-    }
+    // add the listener to the master set
+    FD_SET(listener, &master);
 
-    printf("server: waiting for connections...\n");
+    // keep track of the biggest file descriptor
+    fdmax = listener; // so far, it's this one
 
-    while(1) {  // main accept() loop
-        sin_size = sizeof their_addr;
-        new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size);
-        if (new_fd == -1) {
-            perror("accept");
-            continue;
+    while(1) {
+        read_fds = master; // copy it
+        if (select(fdmax+1, &read_fds, NULL, NULL, NULL) == -1) {
+            perror("select");
+            exit(4);
         }
 
-        inet_ntop(their_addr.ss_family,
-            get_in_addr((struct sockaddr *)&their_addr),
-            s, sizeof s);
-        printf("server: got connection from %s\n", s);
+        // 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);
 
-        // make a struct for the message, number is the number of stations
-        struct Hello hello;
-        if ((recv(new_fd, &hello, sizeof(struct Hello), 0)) == -1)
-        {
-            perror("send");
-            close(new_fd);
-            exit(0);
+                    if (newfd == -1) {
+                        perror("accept");
+                    } else {
+                        struct timeval tv;
+                        tv.tv_sec = 0;
+                        tv.tv_usec = TIMEOUT;
+                        if (setsockopt(newfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0) {
+                            perror("setsockopt");
+                        }
+
+                        uint8_t command_type = -1;
+                        if ((nbytes = recv(newfd, &command_type, 1, 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");
+                            }
+                            // remove user from data structures
+                            close(newfd);
+                            // destroy_user(i);
+                            continue;
+                        }
+
+                        if (command_type != 0) {
+                            char * message = "must send a Hello message first";
+                            send_invalid_command_reply(newfd, strlen(message), message);
+                            close(newfd);
+                            continue;
+                        }
+
+                         // get the udp port
+                        uint16_t udp_port = -1;
+                        int bytes_to_read = sizeof(uint16_t);
+                        if (recv_all(newfd, &udp_port, &bytes_to_read) == -1) {
+                            perror("recv_all");
+                            close(newfd);
+                            // destroy_user(i);
+                            continue;
+                        }
+                        udp_port = ntohs(udp_port);
+
+                        FD_SET(newfd, &master); // add to master set
+                        if (newfd > fdmax) {    // keep track of the max
+                            fdmax = newfd;
+                        }
+                        init_user(newfd);
+                        update_user_udpPort(newfd, udp_port);
+
+                         // 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(newfd, &welcome, &bytes_to_send) == -1)
+                            perror("send_all");
+                }
+                } else {
+                    // handle data from a client
+                    uint8_t command_type = -1;
+                    if ((nbytes = recv(i, &command_type, 1, 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_type == 0) { // we got a Hello commmand
+
+                            // get the udp port
+                            uint16_t udp_port = -1;
+                            int bytes_to_read = sizeof(uint16_t);
+                            if (recv_all(i, &udp_port, &bytes_to_read) == -1) {
+                                perror("recv_all");
+                                close(i);
+                                FD_CLR(i, &master);
+                                destroy_user(i);
+                                continue;
+                            }
+
+                            if (user_data[sockfd_to_user[i]].udpPort != -1) {
+                                // send back in invalid command
+                                char * message = "must not sent more than one Hello message";
+                                send_invalid_command_reply(i, strlen(message), message);
+                                // drop connection upon invalid command
+                                close(i);
+                                FD_CLR(i, &master);
+                                destroy_user(i);
+                                continue;
+                            }
+                        }
+                        else if (command_type == 1) { // we got a SetStation command
+                            // get the station number
+                            
+                            uint16_t station_number = -1;
+                            int bytes_to_read = sizeof(uint16_t);
+                            if (recv_all(i, &station_number, &bytes_to_read) == -1) {
+                                perror("recv_all");
+                                close(i);
+                                FD_CLR(i, &master);
+                                destroy_user(i);
+                                continue;
+                            }
+                            station_number = ntohs(station_number);
+
+                            // check if user has a udpPort to stream to
+                            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;
+                            }
+
+                            // check if station num is in range
+                            if (station_number >= num_stations || station_number < 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, station_number);
+                            send_announce_reply(i, station_number);
+                        }
+                        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);
+
+    if(sockfd > max_sockfd) {
+        max_sockfd = sockfd;
+        int * more_sockfd_to_user = realloc(sockfd_to_user, sizeof(int) * (max_sockfd + 1));
+        if (!more_sockfd_to_user) { perror("realloc"); exit(1); }
+        sockfd_to_user = more_sockfd_to_user;
+    }
+
+    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++;
+        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};
+    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\n", 
+        user_data[index].udpPort, user_data[index].stationNum, user_data[index].sockfd);
+}
+
+void destroy_user(int sockfd) {
+    pthread_mutex_lock(&mutex_user_data);
+    // stop the thread streaming to the user
+    // pthread_t thread = user_data[sockfd_to_user[sockfd]].streamThread;
+    // if (thread != -1) {
+    //     pthread_cancel(thread);
+    // }
+    // "remove" the user from the list of user data
+    user_data[sockfd_to_user[sockfd]] = (user_t) {-1, -1, -1};
+    // map sockfd to -1
+    sockfd_to_user[sockfd] = -1;
 
-        // make a struct for the message, number is the number of stations
-        struct Welcome welcome;
-        welcome.replyType = 2;
-        welcome.numStations = htons(argc - 2);
-        if ((send(new_fd, &welcome, sizeof(struct Welcome), 0)) == -1)
-            perror("send");
-        close(new_fd);
-        exit(0);
+    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 0;
+    return &(((struct sockaddr_in6*)sa)->sin6_addr);
+}
+
+void send_announce_reply(int fd, int station_num) {
+    char* file_path = stations[station_num].filePath;
+    int len_file_path = strlen(file_path);
+
+    char *send_buffer = malloc(len_file_path+2);
+    if (!send_buffer) {
+        perror("malloc in send announce");
+        return;
+    }
+    send_buffer[0] = 3;
+    send_buffer[1] = len_file_path;
+
+    memcpy(send_buffer + 2, file_path, len_file_path);
+
+    size_t bytes_to_send = len_file_path + 2;
+    if (send_all(fd, send_buffer, &bytes_to_send) == -1)
+        perror("send_all");
+
+    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 in send invalid command");
+        return;
+    }
+
+    // type and payload size
+    send_buffer[0] = 4;
+    send_buffer[1] = message_size;
+
+    memcpy(send_buffer + 2, message, message_size);
+
+    int bytes_to_send = message_size + 2;
+    if (send_all(fd, send_buffer, &bytes_to_send) == -1)
+        perror("send");
+
+    free(send_buffer);
+}
+
+// void init_station(int station_num, const char* station_name) {
+//     station_t *station = &station_data[station_num];
+
+//     // open the file
+//     int stream_fd = open(station_name, O_RDONLY);
+//     if (stream_fd == -1) {
+//         perror("open");
+//         return;
+//     }
+//     station->streamFd = stream_fd;
+//     station->filePath = station_name;
+
+//     // setup file buffer
+//     char stream_buffer[MAX_STREAM_RATE];
+//     memset(stream_buffer, 0, MAX_STREAM_RATE);
+
+//     station->fileBufferSize = MAX_STREAM_RATE;
+//     memcpy(&station->fileBufferSize, stream_buffer, MAX_STREAM_RATE);
+
+
+//     // load the first buffer into the stations
+//     seek_stations(station_num);
+// }
+
+// void seek_stations(int station_num) {
+//     station_t *station_info = &station_data[station_num];
+//     memset(&station_info->fileBuffer, 0, MAX_STREAM_RATE);
+//     int bytes_read = read(station_info->streamFd, &station_info->fileBuffer, MAX_STREAM_RATE);
+//     lseek(station_info->streamFd, -16, SEEK_SET);
+//     // printf("station info - bytes read: %d, station_fd: %d, filePath: %s, buffersize: %d\n", bytes_read, station_info->streamFd, station_info->filePath, station_info->fileBufferSize);
+
+//     // time to restart the file
+//     if (bytes_read == 0) {
+//         if (lseek(station_info->streamFd, 0, SEEK_SET) == -1) {
+//             perror("fseek");
+//         }
+//         pthread_t send_announce_thread;
+//         pthread_create(&send_announce_thread, NULL, send_announce_routine, (void *)station_num);
+
+//         // load first chunk
+//         bytes_read = read(station_info->streamFd, &station_info->fileBuffer, MAX_STREAM_RATE);
+//     }
+//     station_info->fileBufferSize = bytes_read;
+// }
+
+
+// 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;
 }
\ No newline at end of file