path: root/client.c

/*
    author: sotech117
    date: 9/25/2023
    course: csci1680
    description: client for snowcast, a music streaming service

    enjoy :)
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <ctype.h>
#include <pthread.h>
#include <arpa/inet.h>
#include "protocol.c"

#define COMMAND_LINE_MAX 1024

// handles the handshake and returns the number of stations
u_int16_t handle_handshake(int sockfd, const char* udp_port);

// routine thread for the command line
void *command_line_routine(void *args);

int l = 0;              // logging
int station_is_set = 0; // if we have a station set
int waiting = 0;        // for command line "snowcast_control>" prompt to be a new lone
int exiting = 0;        // to not have error messages when the program exits "gracefully"

main(int argc, char *argv[]) // no int here for good luck :)
{
    // CHECK AND USE ARGUMENTS
    // -------------------------------------------------------------------------------------------------
    if (argc != 4) {
        fprintf(stderr,"<server IP> <server port> <listener port>\n");
        exit(1);
    }
    const char* tcpPort = argv[2]; // port we use to connect to server's tcp stream
    const char* udpPort = argv[3]; // port we use to connect to server's udp info and command

    // SETUP TCP CONNECTION (getaaadrinfo->socket->connect)
    // -------------------------------------------------------------------------------------------------
    struct addrinfo hints, *servinfo, *p;
    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_INET; // only IPv4
    hints.ai_socktype = SOCK_STREAM;

    // resolve host & make socket
    int sockfd, err;
    if ((err = getaddrinfo(argv[1], tcpPort, &hints, &servinfo)) != 0)
    {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(err));
        return 1;
    }
    // loop through all the results and connect 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("client: socket");
            continue;
        }

        if (connect(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
            close(sockfd);
            perror("client: connect");
            continue;
        }
        break;
    }
    if (p == NULL) {
        fprintf(stderr, "client: failed to connect\n");
        return 2;
    }
    // char s[INET_ADDRSTRLEN]; // for printing the ip address
    // inet_ntop(p->ai_family, get_in_addr((struct sockaddr *)p->ai_addr), s, sizeof s);
    freeaddrinfo(servinfo); // all done with this structure

    // DO HANDSHAKE & PRINT STATION NUMBER
    // -------------------------------------------------------------------------------------------------
    // now that we're connectioned, let's do the handshake
    uint16_t num_stations = handle_handshake(sockfd, udpPort);

    // handle_handshake will end the program on fail
    // so if we're here, num_stations is correct
    fflush(stdout);
    printf("Welcome to Snowcast! The server has %u stations.\n", num_stations);
    fflush(stdout);

    // START COMMAND LINE THREAD
    // -------------------------------------------------------------------------------------------------
    pthread_t command_line_thread;
    pthread_create(&command_line_thread, NULL, command_line_routine, (void*)&sockfd);

    // START WHILE LOOP THAT HANDLES ALL REPLIES
    // -------------------------------------------------------------------------------------------------
    while (69) {
        // get the type of the incoming reply
        uint8_t reply_type = -1;
        // print size of utin8
        if (recv(sockfd, &reply_type, 1, 0) == -1) {
            if (exiting) { // just to remove that pesky error message
                break;
            }
            perror("recv in first byte");
            exit(1);
        }

        if (reply_type == WELCOME) {
            fprintf(stderr, "WECLOME reply received twice. Exiting.\n");
            close(sockfd);
            exit(1);
        }

        if (reply_type == ANNOUNCE) {
            if (!station_is_set) {
                fprintf(stderr, "ANNOUNCE reply received before SETSTATION command. Exiting.\n");
                close(sockfd);
                exit(1);
            }

            // get the string size for the songname
            u_int8_t string_size = -1;
            if (recv(sockfd, &string_size, 1, 0) == -1) {
                perror("recv in announce");
                exit(1);
            }

            // read the songname
            char *song_name = malloc(string_size);
            if(song_name == NULL) { perror("malloc in song name"); }
            int bytes_to_read = string_size;
            if (recv_all(sockfd, song_name, &bytes_to_read) == -1) {
                perror("recv_all in announce");
                exit(1);
            }
            remove_timeout(sockfd); // have received all, so can remove timeout
            if (l) printf("received ANNOUNCE reply.\n");

            // print the songname
            if (!waiting) printf("\n"); // note: this is worth the lines for a clean cmd prompt
            waiting = 0;
            fflush(stdout);
            printf("New song announced: %s\n", song_name);
            printf("snowcast_control> ");
            fflush(stdout);
            free(song_name);
            continue;
        } 

        if (reply_type == INVALID) { // we have an invalid command message
            // get the string size
            u_int8_t string_size = -1;
            if (recv(sockfd, &string_size, 1, 0) == -1) {
                perror("recv in invalid");
                exit(1);
            }
            char *message = malloc(string_size);
            if(message == NULL) { perror("malloc in message"); }
            int bytes_to_read = string_size;
            if (recv_all(sockfd, message, &bytes_to_read) == -1) {
                perror("recv_all in invalid");
                exit(1);
            }
            fflush(stdout);
            printf("received INVALID reply: %s.\nExiting.\n", message);
            fflush(stdout);
            free(message);
            close(sockfd);

            // close the program on all INVALID COMMANDS
            exit(1);
        }

        if (reply_type == STATIONINFO) { // we are getting STATIONINFO
            if (l) printf("received STATIONINFO reply.\n");

            // get the string size, which can be farily long (uint32_t)
            uint32_t buf_string_size = -1;
            int bytes_to_read = sizeof(uint32_t);
            if (recv_all(sockfd, (char *) &buf_string_size, &bytes_to_read) == -1) {
                perror("recv_all 1 in stationinfo");
                exit(1);
            }

            uint32_t string_size = ntohl(buf_string_size);

            // recieve the message
            char *info = malloc(string_size);
            if(info == NULL) { perror("malloc in info"); }
            bytes_to_read = string_size;
            if (recv_all(sockfd, info, &bytes_to_read) == -1) {
                perror("recv_all 2 in stationinfo");
                exit(1);
            }
            remove_timeout(sockfd); // remove the timeout, now that we have the data

            // print the info
            fflush(stdout);
            printf("Station Information:\n%s\n", info);
            printf("snowcast_control> ");
            fflush(stdout);

            free(info);
            continue;
        }

        if (reply_type == STATIONSHUTDOWN) { // we are getting StationShutdown
            if (l) printf("received STATIONSHUTDOWN reply.\n");

            // remove timeout, in case we were waiting for an announce
            remove_timeout(sockfd);

            if (!waiting) printf("\n"); // note: this is worth the lines for a clean cmd prompt :)
            waiting = 0;

            // station no longer set
            station_is_set = 0;
            fflush(stdout);
            printf("This station has shut down. Please select a different station.\n");
            printf("snowcast_control> ");
            fflush(stdout);
            continue;
        }

        if (reply_type == NEWSTATION) { // we are getting NewStation
            if (l) printf("received NEWSTATION reply.\n");

            // get station number
            uint16_t station_number = -1;
            if (recv(sockfd, &station_number, 2, 0) == -1) {
                perror("recv in new station");
                exit(1);
            }
            station_number = ntohs(station_number);

            // print
            fflush(stdout);
            printf("\nThere is now a new station @ index %u.\n", station_number);
            printf("snowcast_control> ");
            fflush(stdout);

            continue;
        }

        // if we're here, lost conneciton to the server -> end the program
        printf("\nsocket to server HUNGUP. Exiting.\n");
        close(sockfd);
        exit(1);
    }
    return 0;
}

/* thread for managing the command line */
void *command_line_routine(void* args) {
    // unpack sockfd as arg
    int sockfd = *(int *) args;

    // buffer for input
    char input[COMMAND_LINE_MAX];

    printf("Enter a number to change to it's station. Enter q to end stream.\n");
    printf("snowcast_control> ");
    fflush(stdout);
    while (420) {
        memset(input, 0, COMMAND_LINE_MAX);
	    char *line = fgets(input, COMMAND_LINE_MAX, stdin);

        // nothing was typed
        if (line == NULL) {
            continue;
        } 
        
        // "q" command: exit the program
        if (strncmp("q\n", input, COMMAND_LINE_MAX) == 0) {
            // end code if type in q
            exiting = 1;
            printf("Exiting.\n");
            close(sockfd);
            exit(0);
        }
        
        // "l" command: STATIONINFO command (EXTRA CREDIT)
        if (strncmp("l\n", input, COMMAND_LINE_MAX) == 0) {
            // send the command to list stations
            if (l) printf("sending LISTSTATIONS command. waiting for STATIONINFO reply.\n");
            apply_timeout(sockfd); // apply a timeout, will be released when we get the reply
            int list_station_reply_type = 5;
            if (send(sockfd, &list_station_reply_type, 1, 0) == -1) {
                perror("send");
                exit(1);
            }
            continue;
        }

        // "log" command: toggle logging
        if (strncmp("log\n", input, COMMAND_LINE_MAX) == 0)
        {
            l = !l;
            printf("LOGGING is now %s!\n", l ? "on" : "off");
            printf("snowcast_control> ");
            fflush(stdout);
            continue;
        }

        // check if this could be a station number
        int inputInt = atoi(input);
        if (input[0] != '0' && inputInt == 0) {
            // if we're in here, it's ~likely~ not a number (ik it's not perfect, sorry :/)
            printf("unknown command: %s", input);
            printf("snowcast_control> ");
            fflush(stdout);
            continue;
        }

        // if we're here, it was a valid number, 
        // & we need to send SETSTATION command.
        if (l) printf("sending SETSTATION command.\n");
        waiting = 1; // just for clean cmd

        // setup struct
        struct SetStation setStation;
        setStation.commandType = SETSTATION;
        setStation.stationNumber = htons(inputInt);
        // send it
        apply_timeout(sockfd); // apply timeout, will be released when we get ANNOUNCE reply
        int bytes_to_send = sizeof(struct SetStation);
        if (send_all(sockfd, (char *) &setStation, &bytes_to_send) == -1) {
            perror("send_all");
            exit(1);
        }

        if (!station_is_set) station_is_set = 1; // update, if needed
        if (l) printf("waiting for ANNOUNCE reply...\n");
    }
    return (NULL);
}

/*
    handles the handshake, given the new socket fd and the udp port of this client
    returns the number of stations
    note: will close the program on failure!
*/
uint16_t handle_handshake(int sockfd, const char* udp_port) {
    if (l) printf("found server, sending HELLO command.\n");

    apply_timeout(sockfd); // apply timeout for handshake

    // after we find connection, we need to send HELLO command
    struct Hello hello;
    hello.commandType = HELLO;
    // convert updPort to an int
    int udp_port_int = atoi(udp_port);
    hello.udpPort = htons(udp_port_int);
    int hello_len = sizeof(struct Hello);
    if (send_all(sockfd, (char *) &hello, &hello_len) == -1) {
        perror("send");
        exit(1);
    }

    if (l) printf("waiting for WELCOME reply...\n");

    // read WELCOME reply type
    uint8_t reply_type = -1;
    // print size of utin8
    if (recv(sockfd, (void *) &reply_type, 1, 0) == -1) { // only one byte, so can use recv
        perror("recv in handshake");
        exit(1);
    }

    if (reply_type != WELCOME) {
        fprintf(stderr, "first reply is not WELCOME. Exiting.\n");
        close(sockfd);
        exit(1);
    }

    // get the number of stations
    int16_t num_stations = -1;
    int bytes_to_read = sizeof(uint16_t);
    if (recv_all(sockfd, (char *) &num_stations, &bytes_to_read) == -1) {
        perror("recv_all in handshake");
        exit(1);
    }
    if (l) printf("received ANNOUNCE reply.\n");

    remove_timeout(sockfd); // remove timeout since we no longer are "waiting" for an immediate reply
    return ntohs(num_stations); // return the num_stations to be printed
}