Tried to work on fixing message string bug

.gitignore

@@ -1 +1,3 @@
 main
+user_file.txt
+*.o

Makefile

@@ -0,0 +1,34 @@
+EXEC_FILE=main
+TARGETS=$(EXEC_FILE).o message.o user.o message_helpers.o file_helpers.o stack.o
+CFLAGS=
+
+
+all: $(EXEC_FILE)
+
+$(EXEC_FILE): $(TARGETS)
+	gcc $(CFLAGS) -o $(EXEC_FILE) $^ -leasysock
+
+
+$(EXEC_FILE).o: $(EXEC_FILE).c
+message.o: message.c
+user.o: user.c
+message_helpers.o: message_helpers.c
+file_helpers.o: file_helpers.c
+stack.o: stack.c
+$(TARGETS):
+	gcc $(CFLAGS) -c -o $@ $^
+
+
+.PHONY: debug
+debug: CFLAGS+=-g
+debug: $(EXEC_FILE)
+
+
+.PHONY: allwarn
+allwarn: CFLAGS+=-Wall -Wextra -pedantic
+allwarn: $(EXEC_FILE)
+
+.PHONY: clean
+clean:
+	rm $(TARGETS)
+	rm $(EXEC_FILE)

README.md

@@ -0,0 +1,14 @@
+## Chat server
+This is a simple, barely-working chat server (which uses a custom protocol). It is written in C, and relies on BSD sockets.
+
+##Usage
+To use it, compile the program with `make`.
+
+
+
+
+TODO:
+-  Finish README
+-  Implement password authentication
+-  Fix bugs with message string manipulation (the actual message isn't being stored correctly, and contains extra characters).
+-  Do additional testing to ensure that everything works correctly (it probably doesn't).

easysock.c

@@ -1,169 +0,0 @@
-#include "easysock.h"
-
-int create_socket(int network, char transport) {  
-	int domain;
-	int type;
-
-	if (network == 4) {
-		domain = AF_INET;
-	} else if (network == 6) {
-		domain = AF_INET6;
-	} else {
-		return -1;
-	}
-
-	if (transport == 'T') {
-		type = SOCK_STREAM;
-	} else if (transport == 'U') {
-		type = SOCK_DGRAM;
-	} else {
-		return -1;
-	}
-
-	int newSock = socket(domain,type,0);
-	return newSock;
-}
-
-
-void create_addr(int network, char* address, int port,struct sockaddr* dest) {
-	if (network == 4) {
-		struct sockaddr_in listen_address;
-		
-		listen_address.sin_family = AF_INET;
-		listen_address.sin_port = htons(port);
-		inet_pton(AF_INET,address,&listen_address.sin_addr);
-		memcpy(dest,&listen_address,sizeof(listen_address));
-		return;	
-
-	} else if (network == 6) {
-		struct sockaddr_in6 listen_ipv6;
-		listen_ipv6.sin6_family = AF_INET6;
-		listen_ipv6.sin6_port = htons(port);
-		inet_pton(AF_INET6,address,&listen_ipv6.sin6_addr);
-		memcpy(dest,&listen_ipv6,sizeof(listen_ipv6));
-		return;
-
-	} else {
-		exit(202);
-	}
-		
-}
-
-int create_local (int network, char transport, char* address, int port,struct sockaddr* addr_struct) {
-	int socket = create_socket(network,transport);
-	if (socket < 0) {
-		exit(errno);
-	}
-	create_addr(network,address,port,addr_struct);
-	int addrlen;
-	if (network == 4) {
-		addrlen = sizeof(struct sockaddr_in);
-	} else if (network == 6) {
-		addrlen = sizeof(struct sockaddr_in6);
-	} else {
-		exit(207);
-	}
-
-	/* The value of addrlen should be the size of the 'sockaddr'. 
-	This should be set to the size of 'sockaddr_in' for IPv4, and 'sockaddr_in6' for IPv6.
-	See https://stackoverflow.com/questions/73707162/socket-bind-failed-with-invalid-argument-error-for-program-running-on-macos */
-
-	int i = bind (socket,addr_struct,(socklen_t)addrlen);
-	if (i < 0) {
-		exit(errno);
-	}
-	return socket;
-}
-
-int create_remote (int network,char transport,char* address,int port,struct sockaddr* remote_addr_struct) {
-
-	struct addrinfo hints;  /* Used to tell getaddrinfo what kind of address we want */
-	struct addrinfo* results; /* Used by getaddrinfo to store the addresses */
-
-
-	if (check_ip_ver(address) < 0) { /* If the address is a domain name */
-		int err_code;
-		char* port_str = malloc(10 * sizeof(char));
-
-		sprintf(port_str,"%d",port); /* getaddrinfo expects a string for its port */
-
-
-		memset(&hints,'\0',sizeof(hints));
-		hints.ai_socktype = char_to_socktype(transport);
-
-		err_code = getaddrinfo(address,port_str,&hints,&results);
-		if (err_code != 0) {
-			exit(err_code);
-		}
-		remote_addr_struct = results->ai_addr;
-		network = inet_to_int(results->ai_family);
-	} else {
-	        create_addr(network,address,port,remote_addr_struct);
-	}
-
-	int socket = create_socket(network,transport);
-	if (socket < 0) {
-                exit(errno);
-        }
-
-       	int addrlen;
-	if (network == 4) {
-		addrlen = sizeof(struct sockaddr_in);
-	} else if (network == 6) {
-		addrlen = sizeof(struct sockaddr_in6);
-	} else {
-		exit(207);
-	}
-
-	/* The value of addrlen should be the size of the 'sockaddr'. 
-	This should be set to the size of 'sockaddr_in' for IPv4, and 'sockaddr_in6' for IPv6.
-	See https://stackoverflow.com/questions/73707162/socket-bind-failed-with-invalid-argument-error-for-program-running-on-macos */
-
-        int i = connect(socket,remote_addr_struct,(socklen_t)addrlen);
-	if (i < 0) {
-		exit(errno);
-	}
-        return socket;
-}
-
-
-int check_ip_ver(char* address) {
-	char buffer[16]; /* 16 chars - 128 bits - is enough to hold an ipv6 address */
-	if (inet_pton(AF_INET,address,buffer) == 1) {
-		return 4;
-	} else if (inet_pton(AF_INET6,address,buffer) == 1) {
-		return 6;
-	} else {
-		return -1;
-	}
-}
-
-int int_to_inet(int network) {
-	if (network == 4) {
-		return AF_INET;
-	} else if (network == 6) {
-		return AF_INET6;
-	} else {
-		exit(207);
-	}
-}
-
-int inet_to_int(int af_type) {
-	if (af_type == AF_INET) {
-		return 4;
-	} else if (af_type == AF_INET6) {
-		return 6;
-	} else {
-		exit(207);
-	}
-}
-
-int char_to_socktype(char transport) {
-	if (transport == 'T') {
-		return SOCK_STREAM;
-	} else if (transport == 'U') {
-		return SOCK_DGRAM;
-	} else {
-		exit(250);
-	}
-}

easysock.h

@@ -1,75 +0,0 @@
-#ifndef EASYSOCK_H_
-#define EASYSOCK_H_
-
-#include <string.h>
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <netdb.h>
-#include <arpa/inet.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <errno.h>
-
-
-/* This function takes:
-a layer 3 - network layer - integer, which must be '4' for IPv4
-and 6 for IPv6; and
-a layer 4 - transport layer - character, which must be 'T' for
-TCP or 'U' for UDP. 
-
-It returns the created socket, or -1 if the socket creation failed.*/
-
-int create_socket(int network, char transport);
-
-
-/* This function fills in the sockaddr struct 'dest' based on the given information.
-'network' is an integer that contains '4' for IPv4 or '6' for IPv6;
-'address' is the address that is filled into the struct;
-port is self-explanatory;
-and dest is a pointer to the sockaddr struct that will be filled in. 
-
-The function exits with error code 202 if the network parameter contained neither '4'
-nor '6'. */
-
-void create_addr(int network, char* address, int port,struct sockaddr* dest);
-
-
-
-/* This function utilizes the above two functions; it creates the socket and
-_binds_ the addresses. It is used for local sockets (server sockets). Parameters are
-same as above. 
-
-It prints the error returned by 'bind' if something went wrong, and exits with errno.*/
-
-int create_local (int network, char transport, char* address, int port,struct sockaddr* addr_struct);
-
-
-/* This function utilizes the same functions as 'create_local' but _connects_ to the
-requested address. It is used for remote sockets (client sockets). The paramters are same
-as above. This function needs an empty 'sockaddr *' structure passed to it, which it will fill.
-
-It prints the error returned by 'connect' if something went wrong, and exits with errno.*/
-
-int create_remote (int network,char transport,char* address,int port,struct sockaddr* remote_addr_struct);
-
-/* check_ip_ver - This function checks if the given string is an IPv4 address (returns 4), 
-IPv6 address (returns 6) or neither (returns -1). */
-
-int check_ip_ver(char* address);
-
-/* int_to_inet - Takes an int value (4 for IPv4, 6 for IPv6) and returns AF_INET or
-AF_INET6 respectively. */
-
-int int_to_inet(int network);
-
-/* char_to_socktype - Takes a character that represents a transport-layer protocol
-(currently only supports 'T' for TCP or 'U' for UDP - exits with error code 250 if 
-the given characters is neither of these) and return the appropriate SOCKTYPE value. */
-
-int char_to_socktype(char transport);
-
-/* inet_to_int - Takes an int value that corresponds to AF_INET or AF_INET6,
-and returns the appropriate int value. */
-int inet_to_int(int af_type);
-
-#endif

file_helpers.c

@@ -0,0 +1,53 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "file_helpers.h"
+
+
+char* file_to_string(char* filename) {
+	FILE* fp = fopen(filename,"r");
+
+	fseek(fp,0,SEEK_END);
+	long file_size = ftell(fp);
+	rewind(fp);
+
+	char* buffer = calloc(sizeof(char),file_size+1);
+
+	fread(buffer,1,file_size,fp);
+
+	rewind(fp);
+	fclose(fp);
+
+	return buffer;
+	
+}
+
+
+
+
+
+/* Finds the number of lines in a file (Which MUST end in a new-line, if the last
+   line is to be counted) */
+
+int num_of_lines(char* filename) {
+
+	int num_lines = 0;
+	FILE* fp = fopen(filename,"r");
+	
+	if (fp == NULL) {
+		return -1;
+	}
+
+
+	for (int c = getc(fp); c != EOF; c = getc(fp)) {
+		if (c == '\n') {
+			num_lines++;
+		}
+	}
+
+	rewind(fp);
+	fclose(fp);
+
+	return num_lines;
+
+}

file_helpers.h

@@ -0,0 +1,11 @@
+
+
+/* Takes a string that represents a filename, and converts the contents 
+of the file into a string */
+char* file_to_string(char* filename);
+
+
+
+
+/*Finds the number of new-line characters in the given file */
+int num_of_lines(char* filename);

main.c

@@ -1,30 +1,58 @@
-#include "message.h"
-#include "user.h"
-#include "easysock.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdbool.h>
 #include <assert.h>
 #include <unistd.h>
+#include <signal.h>
+
+#include "message.h"
+#include "user.h"
+#include "easysock.h"
+#include "file_helpers.h"
+#include "message_helpers.h"
+#include "stack.h"
 
 #define BUFFER_SIZE 10000
 #define MAX_CONNECTIONS 100
+#define DATA_SIZE 50000
+#define MESSAGE_SIZE 50000
 
-int num_of_lines(char* filename);
-char* file_to_string(char* filename);
-User* create_user_list(char* filename);
+User** create_user_list(char* filename);
+void sigint_handler(int dummy);
+User* fetch_user(char* username);
+int user_to_index(User* user);
+bool user_equals(User* this, User* other);
+
+User** users;
+int num_users;
+
+bool stop_running;
 
 int main() {
+	stop_running = false;
+
+	signal(SIGINT,sigint_handler);
+
 	struct sockaddr temp_addr;
 	socklen_t temp_addrlen;
 
 	fd_set read_fd_set;
-	int conn_sockets[MAX_CONNECTIONS] = {0};
-	FD_ZERO(&read_fd_set);
-	char buffer[BUFFER_SIZE];
-	User* users = create_user_list("user_file.txt");
+	int conn_sockets[MAX_CONNECTIONS] = {-1}; 
+	User* to_user[MAX_CONNECTIONS] = {NULL}; 
+	User* from_user[MAX_CONNECTIONS] = {NULL}; 
+	FD_ZERO(&read_fd_set); char buffer[BUFFER_SIZE]; 
+	char data[DATA_SIZE]; 
 
+	num_users = num_of_lines("user_file.txt");
+	users = create_user_list("user_file.txt");
+	
+	Stack* message_stack[num_users];
+
+	for (int i=0;i < num_users; i++) {
+		message_stack[i] = new_stack(10);
+	}
+	
 	struct sockaddr addr_struct;
 	int server_sock = create_local(4,'T',"127.0.0.1",30000,&addr_struct);
 	conn_sockets[0] = server_sock;
@@ -33,7 +61,7 @@ int main() {
 
 	while (true) {
 		FD_ZERO(&read_fd_set);
-		for (int i=0; i < sizeof(conn_sockets); i++) {
+		for (int i=0; i < MAX_CONNECTIONS; i++) {
 			if (conn_sockets[i] > 0) {
 				FD_SET(conn_sockets[i],&read_fd_set);
 			}
@@ -44,7 +72,7 @@ int main() {
 		if (num_conns > 0) {
 			if (FD_ISSET(conn_sockets[0],&read_fd_set)) {
 				int client_sock = accept(conn_sockets[0],&temp_addr,&temp_addrlen);
-				for (int i=0;i < sizeof(conn_sockets); i++) {
+				for (int i=0;i < MAX_CONNECTIONS; i++) {
 					if (conn_sockets[i] <= 0) {
 						conn_sockets[i] = client_sock;
 						break;
@@ -52,41 +80,150 @@ int main() {
 				}
 			}
 
-			for (int i=1; i < sizeof(conn_sockets); i++) {
-				printf("Checking FD: %d\n",i);
-				if (FD_ISSET(conn_sockets[i],&read_fd_set)) {
-					int num_bytes_read = recv(conn_sockets[i],buffer,sizeof(buffer),0);
-					if (num_bytes_read <= 0) {
-						close(conn_sockets[i]);
-						conn_sockets[i] = -1;
-					} else {
-						for (int i=0;i<num_bytes_read;i++) {
-							printf("%c",buffer[i]);
-						}
-					}
+			for (int i=1; i < MAX_CONNECTIONS; i++) {
 
-					
+				memset(data,0x00,DATA_SIZE);
+
+				if (FD_ISSET(conn_sockets[i],&read_fd_set)) {
+
+					while ( strstr(buffer,"END_OF_DATA") == NULL ) {
+						int num_bytes_read = recv(conn_sockets[i],buffer,sizeof(buffer),0);
+                               	                if (num_bytes_read <= 0) {
+							close(conn_sockets[i]);
+							conn_sockets[i] = 0;
+							to_user[i] = NULL;
+							goto continue_for_loop;
+                                                } 
+						strcat(data, buffer);
+					}
+					strcat(data,"\0"); 
+
+					buffer[0] = '\0'; /* Clear the buffer */
+
+					char* send_or_receive = malloc(10);
+					int k=0;
+					while (*(data + k) != '\n') {
+						k++;
+					}
+					memcpy(send_or_receive,data,k);
+
+					if (strstr(send_or_receive, "SENDING") != NULL) {
+						if (from_user[i] == NULL) {
+							from_user[i] = fetch_user(fetch_from_string(data,"IAM"));
+							if (from_user[i] == NULL) {
+								printf("Please identify yourself.\n");
+								close(conn_sockets[i]);
+								continue;
+							} else {
+								printf("You are %s\n",from_user[i]->username);
+							}
+						}
+	
+						if (to_user[i] == NULL) {
+							to_user[i] = fetch_user(fetch_from_string(data,"TO"));
+							if (to_user[i] == NULL) {
+								printf("Invalid user or message format.\n");
+								close(conn_sockets[i]);
+								continue;
+							} else {
+								printf("Message intended for %s\n",to_user[i]->username);
+							}
+						}
+
+						char* message_string = malloc(sizeof(char) * MESSAGE_SIZE);	
+						memset(message_string, 0x00, MESSAGE_SIZE);
+						message_string = fetch_message_string(data);
+						if (message_string == NULL) {
+							printf("Invalid message.\n");
+							return -10;
+						}	
+	
+						printf("Your message is: \n------------------\n%s\n------------------\n",message_string);
+	
+						if (user_to_index(to_user[i]) < 0) {
+							printf("Recipient user does not exist!\n");
+							return -20;
+						}
+	
+						Message* message = new_message(message_string,from_user[i],to_user[i]);
+						stack_push( message_stack[user_to_index(to_user[i])],message );
+	
+						printf("Message has been pushed onto stack for %s\n",to_user[i]->username);
+	
+					} else if (strstr(send_or_receive, "RECEIVING") != NULL) {
+
+                                                if (from_user[i] == NULL) {
+                                                        from_user[i] = fetch_user(fetch_from_string(data,"IAM"));
+                                                        if (from_user[i] == NULL) {
+                                                                printf("Please identify yourself.\n");
+                                                                close(conn_sockets[i]);
+                                                                continue;
+                                                        } else {
+                                                                printf("You are %s\n",from_user[i]->username);
+                                                        }
+                                                }
+
+						int num_of_messages;
+						char* num_of_messages_string = fetch_from_string(data,"GETLAST");
+
+						if (num_of_messages_string == NULL) {
+							printf("Invalid GET request.\n");
+							return -30;
+						} else {
+							if (strstr(num_of_messages_string,"ALL") != NULL) {
+								num_of_messages = stack_size(message_stack[user_to_index(from_user[i])]);
+							} else {
+								num_of_messages = atoi(num_of_messages_string);
+							}
+						}
+
+						if (num_of_messages > stack_size(message_stack[user_to_index(from_user[i])])) {
+							num_of_messages = stack_size(message_stack[user_to_index(from_user[i])]);
+						}
+							
+						for (int k=0;k<num_of_messages;k++) {
+							Message* message = stack_pop(message_stack[user_to_index(from_user[i])]);
+							printf("You have a message from %s"
+								", sent at %s"
+								": \"%s\"\n",
+								message->sender->username,
+								asctime(message->timeinfo),
+								message->text);
+						}
+						
+					} else {
+						printf("You are not sending or receiving.\n");
+					}
+					close(conn_sockets[i]);
+					conn_sockets[i] = -1;
+
+					continue_for_loop:
+					memset(data,0,DATA_SIZE);
+					memset(buffer,0,BUFFER_SIZE);
+					to_user[i] = NULL;
+					from_user[i] = NULL;
 				}
 			}
+		
 
+			if (stop_running == true) {
+				printf("Stopping...\n");
+				for (int i=MAX_CONNECTIONS-1; i>= 0;  i--) {
+					close(i);
+					close(conn_sockets[i]);
+				}
+				return 130;
+			}
 
 		}
-		
 
 
 	}
-
-//	Message message = new_message("Hello, this is a text message",users[0],users[1]);
-
-
-
-//	printf("Message was: %s\nSentfrom: %s\nSent to: %s\nWith password: %s\nSent at: %s\n",message.text, message.sender.username, message.recipient.username, message.recipient.password, asctime(&message.timeinfo));
-
 	
 }
 
 
-User* create_user_list(char* filename) {
+User** create_user_list(char* filename) {
 
 	/* Structure of user file - <username> <password> on every line */
 
@@ -94,13 +231,17 @@ User* create_user_list(char* filename) {
         char* file_str = file_to_string(filename);
 
         char* token = malloc(sizeof(char) * 30);
-        User* users = calloc(num_users, sizeof(User));
+        User** users = malloc (num_users * sizeof(User*));
+
+	for (int i=0;i<num_users;i++) {
+		(*(users+i)) = malloc(sizeof(User));
+	}
 
         token = strtok(file_str," \r\n");
         for (int i=0;i<num_users;i++) {
-                users[i].username = token;
+		(*(users + i))->username = strdup(token);
                 token = strtok(NULL," \r\n");
-                users[i].password = token;
+                (*(users + i))->password = strdup(token);
                 token = strtok(NULL," \r\n");
         }
 
@@ -108,50 +249,43 @@ User* create_user_list(char* filename) {
 
 }
 
-
-
-char* file_to_string(char* filename) {
-	FILE* fp = fopen(filename,"r");
-
-	fseek(fp,0,SEEK_END);
-	long file_size = ftell(fp);
-	rewind(fp);
-
-	char* buffer = calloc(sizeof(char),file_size+1);
-
-	fread(buffer,1,file_size,fp);
-
-	fclose(fp);
-
-	return buffer;
-	
+void sigint_handler(int dummy) {
+	stop_running = true;
+	printf("sigint_handler is stopping...\n");
+	exit(130);
 }
 
-
-
-
-
-/* Finds the number of lines in a file (Which MUST end in a new-line, if the last
-   line is to be counted) */
-
-int num_of_lines(char* filename) {
-
-	int num_lines = 0;
-	FILE* fp = fopen(filename,"r");
-	
-	if (fp == NULL) {
-		return -1;
+User* fetch_user(char* username) {
+	if (username == NULL) {
+		return NULL;
 	}
 
-
-	for (int c = getc(fp); c != EOF; c = getc(fp)) {
-		if (c == '\n') {
-			num_lines++;
+	for (int i=0;i<num_users;i++) {
+		if (strcmp(users[i]->username, username) == 0) {
+			return users[i];
 		}
 	}
 
-	fclose(fp);
+	return NULL;
+}
 
-	return num_lines;
+int user_to_index(User* user) {
+	int index = -1;
+	for (int i=0;i < num_users; i++) {
+		if (user_equals(users[i],user) == true) {
+			index = i;
+			break;
+		}
+	}
+
+	return index;
 
 }
+
+bool user_equals(User* this, User* other) {
+	if (( strcmp(this->username,other->username) == 0 ) && ( strcmp(this->password,other->password) == 0 )) {
+		return true;
+	} else {
+		return false;
+	}
+}

message.c

@@ -4,22 +4,30 @@
 #include <time.h>
 #include "message.h"
 
-Message new_message(char* string, User from, User to) {
-	Message new_message;
+Message* new_message(char* string, User* from, User* to) {
+	Message* new_message;
 
-	new_message.text = malloc((strlen(string)+1)*sizeof(char));
-	strcpy(new_message.text,string);
+	new_message = malloc(sizeof(Message));
+	new_message->text = malloc((strlen(string)+1)*sizeof(char));
+	strcpy(new_message->text,string);
 	
-	new_message.sender = from;
-	new_message.recipient = to;
+	new_message->sender = malloc(sizeof(User));
+	new_message->recipient = malloc(sizeof(User));
+
+	memcpy(new_message->sender, from, sizeof(User));
+	memcpy(new_message->recipient, to, sizeof(User));
+
+
+//	*(new_message->sender) = *from;
+//	*(new_message->recipient) = *to;
 
 	time_t rawtime;
-	struct tm timeinfo;
+	struct tm* timeinfo;
 
 	time(&rawtime);
-	timeinfo = *localtime(&rawtime);
+	timeinfo = localtime(&rawtime);
 
-	new_message.timeinfo = timeinfo;
+	new_message->timeinfo = timeinfo;
 
 	return new_message;	
 

message.h

@@ -10,11 +10,11 @@ typedef struct Message_s Message;
 
 struct Message_s {
 	char* text;
-	struct tm timeinfo;
-	User sender;
-	User recipient;
+	struct tm* timeinfo;
+	User* sender;
+	User* recipient;
 };
 
-Message new_message(char* text,User from,User to);
+Message* new_message(char* text,User* from,User* to);
 
 #endif

message_helpers.c

@@ -0,0 +1,81 @@
+#include <easysock.h>
+
+#include "message_helpers.h"
+
+char* fetch_from_string(char* message, char* indicator) {
+
+	char* message_copy = malloc(strlen(message));
+	strcpy(message_copy,message);
+
+        char* token = malloc (sizeof(char) * strlen(message_copy));
+
+	char* string_to_search = malloc(strlen(indicator) + 1);
+	strcpy(string_to_search,indicator);
+	strcat(string_to_search,":");
+        token = strtok(message_copy," r\n");
+	while (strcmp(token,string_to_search) != 0) {
+		token = strtok(NULL," \r\n");
+		if (token == NULL) {
+			return NULL;
+		}
+	}
+        token = strtok(NULL," \r\n");
+        return token;
+
+}
+
+char* fetch_message_string(char* message) {
+
+	char* message_copy = malloc(strlen(message));
+	strcpy(message_copy,message);
+
+	int num_of_terminators = 0;
+	int start_index = 0;
+	int end_index = 0;
+	int message_length = 0;
+
+
+	char* start = strstr(message_copy,"START_OF_MESSAGE");
+	if (start == NULL) {
+		return NULL;
+	}
+	start_index = start - message_copy;
+	start_index += strlen("START_OF_MESSAGE");
+
+	while (*(message_copy + start_index) == '\n' || *(message_copy + start_index) == '\r') {
+		start_index++;
+	}
+	
+	char* end = strstr(message_copy,"END_OF_MESSAGE");
+	if (end == NULL) {
+		return NULL;
+	}
+	end_index = end - message_copy;
+
+	if (*(message_copy + end_index-2) == '\r') {
+		num_of_terminators = 2;
+	} else {
+		num_of_terminators = 1;
+	}
+
+	end_index -= num_of_terminators;
+
+	message_length = end_index - start_index;
+	char* message_string = malloc(message_length + 2);
+
+	printf("Message goes from %d to %d\n",start_index,end_index);
+
+	for (int i=0; i<message_length; i++) { /* The reason the upper-bound is message_length-1 is because the last 
+						character is a new-line, which the user would not have typed. */
+
+		*(message_string + i) = *(message_copy + start_index + i);
+		printf("%c",*(message_string + i));
+	}
+
+	strcat(message_string,"\0");
+
+//	printf("%s\n",message_string);
+
+//	*(message_string + (message_length - num_of_terminators)) = '\0';
+	return message_string;
+}

message_helpers.h

@@ -0,0 +1,12 @@
+
+/* If the message contains a string of the form:
+<Indicator>: <Value>
+Then return 'value' */
+char* fetch_from_string(char* message, char* indicator);
+
+/* If the message contains a string of the form:
+START_OF_MESSAGE
+<text>
+END_OF_MESSAGE
+Then return <text> */
+char* fetch_message_string(char* message);

stack.c

@@ -0,0 +1,62 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <stdbool.h>
+
+#include "stack.h"
+
+struct Stack {
+	void** data;
+	int top_index;
+	int capacity;
+	int curr_size;
+};
+
+Stack* new_stack(int stack_size) {
+	assert(stack_size > 0);
+	Stack* my_stack = malloc(sizeof(Stack));
+	my_stack->capacity = stack_size;
+	my_stack->data = malloc(stack_size);
+	my_stack->top_index = 0;
+	my_stack->curr_size = 0;
+	return my_stack;
+}
+
+void stack_push(Stack* stack,void* element) {
+	if (stack->curr_size >= stack->capacity-1) {
+		stack->data = realloc(stack->data, stack->capacity*2);
+		stack->capacity *= 2;
+	}
+	*(stack->data + stack->top_index) = element;
+	stack->top_index++;
+	stack->curr_size++;
+	return;
+}
+
+void* stack_pop(Stack* stack) {
+	assert( !(stack_isEmpty(stack)) );
+//	free(stack->data + stack->top_index);
+	stack->top_index--;
+	void* to_return = *(stack->data + stack->top_index);
+	*(stack->data + stack->top_index) = NULL;
+
+	stack->curr_size--;
+
+	return to_return;
+}
+
+void* stack_peek(Stack* stack) {
+	void* to_return = *(stack->data + stack->top_index - 1);
+	return to_return;
+}
+
+int stack_size(Stack* stack) {
+	return (stack->curr_size);
+}
+
+bool stack_isEmpty(Stack* stack) {
+	if (stack_size(stack) == 0) {
+		return true;
+	}
+	return false;
+}

stack.h

@@ -0,0 +1,11 @@
+#include <stdbool.h>
+
+typedef struct Stack Stack;
+
+Stack* new_stack(int stack_size);
+
+void stack_push(Stack* stack, void* element);
+void* stack_pop(Stack* stack);
+void* stack_peek(Stack* stack);
+int stack_size(Stack* stack);
+bool stack_isEmpty(Stack* stack);