diff --git a/image_tagger.c b/image_tagger.c
new file mode 100644
index 0000000000000000000000000000000000000000..735ba45a801115c57ff3e9e8ad2ad9d2bbcedc8c
--- /dev/null
+++ b/image_tagger.c
@@ -0,0 +1,573 @@
+/*
+** http-server.c
+*/
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <arpa/inet.h>
+#include <fcntl.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <strings.h>
+#include <sys/select.h>
+#include <sys/sendfile.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+
+// constants
+static char const * const HTTP_200_FORMAT = "HTTP/1.1 200 OK\r\n\
+Content-Type: text/html\r\n\
+Content-Length: %ld\r\n\r\n";
+static char const * const HTTP_400 = "HTTP/1.1 400 Bad Request\r\nContent-Length: 0\r\n\r\n";
+static int const HTTP_400_LENGTH = 47;
+static char const * const HTTP_404 = "HTTP/1.1 404 Not Found\r\nContent-Length: 0\r\n\r\n";
+static int const HTTP_404_LENGTH = 45;
+static int GAMEOVER_STATE = 7;
+static int READY_STATE = 3;
+static int ENDGAME_STATE = 6;
+static int MAX_LENGTH = 20;
+
+// represents the types of method
+typedef enum
+{
+ GET,
+ POST,
+ UNKNOWN
+} METHOD;
+
+// Structure for player
+typedef struct Player {
+ char player_name[20];
+ int player_socket;
+ int count;
+ char keyword_list[20][20];
+ int player_status;
+}Player;
+
+Player* current_player(int sockfd,Player *player1, Player *player2);
+
+static bool handle_http_request(int sockfd,Player *player1, Player *player2)
+{
+ // try to read the request
+ char buff[2049];
+ char keyword[20];
+ char* starting_keyword;
+ char* ending_keyword;
+ bool end = false;
+ int n = read(sockfd, buff, 2049);
+ if (n <= 0)
+ {
+ if (n < 0)
+ perror("read");
+ else
+ printf("socket %d close the connection\n", sockfd);
+ return false;
+ }
+
+ // terminate the string
+ buff[n] = 0;
+
+ char * curr = buff;
+
+ // parse the method
+ METHOD method = UNKNOWN;
+ if (strncmp(curr, "GET ", 4) == 0)
+ {
+ curr += 4;
+ method = GET;
+ }
+ else if (strncmp(curr, "POST ", 5) == 0)
+ {
+ curr += 5;
+ method = POST;
+ }
+ else if (write(sockfd, HTTP_400, HTTP_400_LENGTH) < 0)
+ {
+ perror("write");
+ return false;
+ }
+
+ // sanitise the URI
+ while (*curr == '.' || *curr == '/')
+ ++curr;
+ // if player quit or the other player quited
+ if((strstr(buff,"quit=Quit"))||player1->player_status == GAMEOVER_STATE ||player2->player_status == GAMEOVER_STATE){
+ // send quit page
+ struct stat st;
+ stat("7_gameover.html", &st);
+ n = sprintf(buff, HTTP_200_FORMAT, st.st_size);
+ // send the header first
+ if (write(sockfd, buff, n) < 0)
+ {
+ perror("write");
+ return false;
+ }
+ // send the file
+ int filefd = open("7_gameover.html", O_RDONLY);
+ do
+ {
+ n = sendfile(sockfd, filefd, NULL, 2048);
+ }
+ while (n > 0);
+ if (n < 0)
+ {
+ perror("sendfile");
+ close(filefd);
+ return false;
+ }
+ close(filefd);
+ // change player status to 7(quit state)
+ if(player1->player_socket==sockfd){
+ player1->player_status=GAMEOVER_STATE;
+ }else if(player2->player_socket == sockfd){
+ player2->player_status=GAMEOVER_STATE;
+ }
+
+ // reset player struct (reset game)
+ if(player1->player_status == GAMEOVER_STATE &&player2->player_status ==GAMEOVER_STATE){
+ player1->player_status = 0;
+ strcpy(player1->player_name,"none");
+ player1->player_socket = 0;
+ player1->count = 0;
+ player2->player_status = 0;
+ strcpy(player2->player_name,"none");
+ player2->player_socket = 0;
+ player2->count = 0;
+ }
+ return false;
+ }
+ // if player guessing
+ else if(strstr(buff,"&guess=Guess")){
+ // if both player are ready
+ if(player1->player_status == READY_STATE && player2->player_status == READY_STATE){
+ // reset keyword
+ memset(keyword, 0, sizeof(char)*20);
+ // find length of keyword and copy keyword using strncpy
+ starting_keyword = strstr(buff,"keyword=");
+ ending_keyword = strstr(starting_keyword, "&guess=Guess");
+ int keyword_length = ending_keyword-starting_keyword-8;
+ strncpy(keyword,strstr(buff,"keyword=")+8,keyword_length);
+
+ // find current player
+ if(player1->player_socket==sockfd){
+ // place keyword into player keyword_list
+ strcpy(player1->keyword_list[player1->count],keyword);
+ player1->count++;
+ // check if keyword appeared in other player keyword_list
+ for(int k=0; k<=player2->count;k++){
+ // if keyword appeared in other player keyword_list change both player state to victory state(6)
+ if(strcmp(keyword,player2->keyword_list[k])==0){
+ player1->player_status = ENDGAME_STATE;
+ player2->player_status = ENDGAME_STATE;
+ }
+ }
+ }
+ else if(player2->player_socket == sockfd){
+ // place keyword into player keyword_list
+ strcpy(player2->keyword_list[player2->count],keyword);
+ player2->count++;
+ // check if keyword appeared in other player keyword_list
+ for(int k=0; k<=player1->count;k++){
+ // if keyword appeared in other player keyword_list change both player state to endgame state(6)
+ if(strcmp(keyword,player1->keyword_list[k])==0){
+ player1->player_status = ENDGAME_STATE;
+ player2->player_status = ENDGAME_STATE;
+ }
+ }
+ }
+ // if either player in endgame state
+ if (player2->player_status == ENDGAME_STATE||player1->player_status == ENDGAME_STATE) {
+ //reset players keyword_list
+ player1->count = 0;
+ player2->count = 0;
+ memset(player1->keyword_list,0,sizeof(player1->keyword_list [0][0])* 20* 20);
+ memset(player2->keyword_list,0,sizeof(player2->keyword_list [0][0])* 20 * 20);
+
+ // send endgame page
+ struct stat st;
+ stat("6_endgame.html", &st);
+ n = sprintf(buff, HTTP_200_FORMAT, st.st_size);
+ // send the header first
+ if (write(sockfd, buff, n) < 0)
+ {
+ perror("write");
+ return false;
+ }
+ // send the file
+ int filefd = open("6_endgame.html", O_RDONLY);
+ do
+ {
+ n = sendfile(sockfd, filefd, NULL, 2048);
+ }
+ while (n > 0);
+ if (n < 0)
+ {
+ perror("sendfile");
+ close(filefd);
+ return false;
+ }
+ close(filefd);
+ // if player keyword not match(not victory state)
+ }else{
+
+ // send accepted file
+ struct stat st;
+ stat("4_accepted.html", &st);
+ char all_keyword[500];
+ long current_length=0;
+
+ // copy keywords in keyword_list to all_keyword string
+ // calculate the length of extra characters
+ for(int j=0;j<current_player(sockfd,player1,player2)->count;j++){
+ strcpy(all_keyword+current_length,current_player(sockfd,player1,player2)->keyword_list[j]);
+ current_length += strlen(current_player(sockfd,player1,player2)->keyword_list[j]);
+ strcpy(all_keyword+current_length,",");
+ current_length += 1;
+ strcpy(all_keyword+current_length," ");
+ current_length += 1;
+ }
+
+ // add size
+ long size = st.st_size + current_length;
+ n = sprintf(buff, HTTP_200_FORMAT, size);
+ // send the header first
+ if (write(sockfd, buff, n) < 0)
+ {
+ perror("write");
+ return false;
+ }
+ // read the content of the HTML file
+ int filefd = open("4_accepted.html", O_RDONLY);
+ n = read(filefd, buff, 2048);
+ if (n < 0)
+ {
+ perror("read");
+ close(filefd);
+ return false;
+ }
+ close(filefd);
+ // print all_keyword
+ // replace behind with body and html
+ strncpy(strstr(buff,"</body>"), all_keyword,current_length);
+ strncpy(strstr(buff,all_keyword)+current_length,"</body>\n</html>",13);
+
+ if (write(sockfd, buff, size) < 0)
+ {
+ perror("write");
+ return false;
+ }
+ }
+ // check if player in victory state (for player after the other player win)
+ }else if(current_player(sockfd,player1,player2)->player_status == ENDGAME_STATE){
+ // send endgame page
+ struct stat st;
+ stat("6_endgame.html", &st);
+ n = sprintf(buff, HTTP_200_FORMAT, st.st_size);
+ // send the header first
+ if (write(sockfd, buff, n) < 0)
+ {
+ perror("write");
+ return false;
+ }
+ // send the file
+ int filefd = open("6_endgame.html", O_RDONLY);
+ do
+ {
+ n = sendfile(sockfd, filefd, NULL, 2048);
+ }
+ while (n > 0);
+ if (n < 0)
+ {
+ perror("sendfile");
+ close(filefd);
+ return false;
+ }
+ close(filefd);
+ // if other player not ready not in ready state(3)
+ }else{
+ // send discarded page
+ struct stat st;
+ stat("5_discarded.html", &st);
+ n = sprintf(buff, HTTP_200_FORMAT, st.st_size);
+ // send the header first
+ if (write(sockfd, buff, n) < 0)
+ {
+ perror("write");
+ return false;
+ }
+ // send the file
+ int filefd = open("5_discarded.html", O_RDONLY);
+ do
+ {
+ n = sendfile(sockfd, filefd, NULL, 2048);
+ }
+ while (n > 0);
+ if (n < 0)
+ {
+ perror("sendfile");
+ close(filefd);
+ return false;
+ }
+ }
+ }
+ // request intro page
+ else if (*curr == ' '){
+ if (method == GET)
+ {
+ //send intro page
+ struct stat st;
+ stat("1_intro.html", &st);
+ n = sprintf(buff, HTTP_200_FORMAT, st.st_size);
+ // send the header first
+ if (write(sockfd, buff, n) < 0)
+ {
+ perror("write");
+ return false;
+ }
+ // send the file
+ int filefd = open("1_intro.html", O_RDONLY);
+ do
+ {
+ n = sendfile(sockfd, filefd, NULL, 2048);
+ }
+ while (n > 0);
+ if (n < 0)
+ {
+ perror("sendfile");
+ close(filefd);
+ return false;
+ }
+ close(filefd);
+ }
+ else if (method == POST)
+ {
+
+ // locate username
+ char * username = strstr(buff, "user=") + 5;
+ char username_copy[20];
+ // ensure username is empty
+ memset(username_copy, 0, sizeof(char)*MAX_LENGTH);
+ // copy username
+ strcpy(username_copy,username);
+ int username_length = strlen(username);
+ long added_length = username_length;
+
+ //set player name and socket
+ if(!strcmp(player1->player_name, "none")){
+ strcpy(player1->player_name,username);
+ player1->player_socket= sockfd;
+ player1->player_status = 0;
+ }else if(!strcmp(player2->player_name, "none")){
+ strcpy(player2->player_name,username);
+ player2->player_socket = sockfd;
+ player2->player_status = 0;
+ }
+ // get the size of the file
+ struct stat st;
+ stat("2_start.html", &st);
+ // increase file size to accommodate the username
+ long size = st.st_size + added_length;
+ n = sprintf(buff, HTTP_200_FORMAT, size);
+ // send the header first
+ if (write(sockfd, buff, n) < 0)
+ {
+ perror("write");
+ return false;
+ }
+ // read the content of the HTML file
+ int filefd = open("2_start.html", O_RDONLY);
+ n = read(filefd, buff, 2048);
+ if (n < 0)
+ {
+ perror("read");
+ close(filefd);
+ return false;
+ }
+ close(filefd);
+ // move the trailing part backward
+ // copy the username
+ strncpy(strstr(buff,"</body>"), username_copy, username_length);
+ strncpy(strstr(buff,username_copy)+username_length,"</body>\n</html>",13);
+
+
+ if (write(sockfd, buff, size) < 0)
+ {
+ perror("write");
+ return false;
+ }
+ }
+ // request for start (start button pressed)
+ }else if(strstr(buff,"?start=Start")){
+ if (method == GET)
+ {
+ // change player state to read state (3)
+ if(player1->player_socket==sockfd){
+ player1->player_status= READY_STATE;
+ }else if(player2->player_socket == sockfd){
+ player2->player_status= READY_STATE;
+ }
+ // get the size of the file
+ struct stat st;
+ stat("3_first_turn.html", &st);
+ n = sprintf(buff, HTTP_200_FORMAT, st.st_size);
+ // send the header first
+ if (write(sockfd, buff, n) < 0)
+ {
+ perror("write");
+ return false;
+ }
+ // send the file
+ int filefd = open("3_first_turn.html", O_RDONLY);
+ do
+ {
+ n = sendfile(sockfd, filefd, NULL, 2048);
+ }
+ while (n > 0);
+ if (n < 0)
+ {
+ perror("sendfile");
+ close(filefd);
+ return false;
+ }
+ close(filefd);
+ }else{
+ // never used, just for completeness
+ fprintf(stderr, "no other methods supported");
+ }
+ // send 404
+ }
+ else if (write(sockfd, HTTP_404, HTTP_404_LENGTH) < 0)
+ {
+ perror("write");
+ return false;
+ }
+
+ return true;
+}
+
+int main(int argc, char * argv[])
+{
+ if (argc < 3)
+ {
+ fprintf(stderr, "usage: %s ip port\n", argv[0]);
+ return 0;
+ }
+
+ // create TCP socket which only accept IPv4
+ int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+ if (sockfd < 0)
+ {
+ perror("socket");
+ exit(EXIT_FAILURE);
+ }
+
+ // reuse the socket if possible
+ int const reuse = 1;
+ if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(int)) < 0)
+ {
+ perror("setsockopt");
+ exit(EXIT_FAILURE);
+ }
+
+ // create and initialise address we will listen on
+ struct sockaddr_in serv_addr;
+ bzero(&serv_addr, sizeof(serv_addr));
+ serv_addr.sin_family = AF_INET;
+ // if ip parameter is not specified
+ serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
+ serv_addr.sin_port = htons(atoi(argv[2]));
+
+ //create 2 players
+ Player player1;
+ strcpy(player1.player_name,"none");
+ player1.count = 0;
+ Player player2;
+ strcpy(player2.player_name,"none");
+ player2.count = 0;
+
+ // bind address to socket
+ if (bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
+ {
+ perror("bind");
+ exit(EXIT_FAILURE);
+ }
+
+ // listen on the socket
+ listen(sockfd, 5);
+
+ // initialise an active file descriptors set
+ fd_set masterfds;
+ FD_ZERO(&masterfds);
+ FD_SET(sockfd, &masterfds);
+ // record the maximum socket number
+ int maxfd = sockfd;
+
+ while (1)
+ {
+ // monitor file descriptors
+ fd_set readfds = masterfds;
+ if (select(FD_SETSIZE, &readfds, NULL, NULL, NULL) < 0)
+ {
+ perror("select");
+ exit(EXIT_FAILURE);
+ }
+
+ // loop all possible descriptor
+ for (int i = 0; i <= maxfd; ++i)
+ // determine if the current file descriptor is active
+ if (FD_ISSET(i, &readfds))
+ {
+ // create new socket if there is new incoming connection request
+ if (i == sockfd)
+ {
+ struct sockaddr_in cliaddr;
+ socklen_t clilen = sizeof(cliaddr);
+ int newsockfd = accept(sockfd, (struct sockaddr *)&cliaddr, &clilen);
+ if (newsockfd < 0)
+ perror("accept");
+ else
+ {
+ // add the socket to the set
+ FD_SET(newsockfd, &masterfds);
+ // update the maximum tracker
+ if (newsockfd > maxfd)
+ maxfd = newsockfd;
+ // print out the IP and the socket number
+ char ip[INET_ADDRSTRLEN];
+ printf(
+ "new connection from %s on socket %d\n",
+ // convert to human readable string
+ inet_ntop(cliaddr.sin_family, &cliaddr.sin_addr, ip, INET_ADDRSTRLEN),
+ newsockfd
+ );
+ }
+ }
+ // a request is sent from the client
+ else if (!handle_http_request(i,&player1,&player2))
+ {
+ close(i);
+ FD_CLR(i, &masterfds);
+ }
+ }
+ }
+
+ return 0;
+}
+
+// find current player
+Player* current_player(int sockfd,Player *player1, Player *player2){
+ Player* playerbot;
+ if(player1->player_socket==sockfd){
+ return player1;
+ }else if(player2->player_socket == sockfd){
+ return player2;
+ }
+ return playerbot;
+}