Quiz CGI-Script

quiz.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sqlite3.h>

void read_teachers(sqlite3* handler) {
	sqlite3_stmt* stmt;
	int ret = sqlite3_prepare(handler, "SELECT * FROM teachers", -1, &stmt, NULL);
	if(ret != SQLITE_OK) {
		printf("ERROR,SQLITE SELECT %d\n", ret);
		return;
	}
	printf("OK\n");
	
	while(sqlite3_step(stmt) != SQLITE_DONE) {
		int id = sqlite3_column_int(stmt, 0);
		const char* name = sqlite3_column_text(stmt, 1);
		printf("%d,%s\n", id, name);
	}
	sqlite3_finalize(stmt);
}

typedef struct {
	int image;
	int teacher;
} Assign;

int is_assign_correct(Assign assign, Assign correct[100], int len) {
	int i;
	for(i = 0; i < len; i++)
		if(assign.image == correct[i].image && assign.teacher == correct[i].teacher)
			return 1;
	return 0;
}

int contains(int search, int list[100], int len) {
	int i;
	for(i = 0; i < len; i++)
		if(list[i] == search)
			return 1;
	return 0;
}

int are_assigns_valid(Assign assigns[100], int len) {
	int i;
	int images[100], teachers[100];
	for(i = 0; i < len; i++) {
		images[i] = assigns[i].image;
		teachers[i] = assigns[i].teacher;
		if(contains(images[i], images, i) || contains(teachers[i], teachers, i))
			return 0;
	}
	return 1;
}

int parse_assigns(char* str, Assign assigns[100]) {
	int i = 0;
	
	char* part = strtok(str, ",");
	if(part == NULL)
		return -1;
	while(part != NULL) {
		int len = strlen(part);
		if(len == 0)
			continue;

		char* mid = strchr(part, (int) ':');
		if(mid == NULL)
			return -1;

		int pos = mid - part;
		if(pos == 0 || pos == len-1)
			return -1;

		int n2 = atoi(mid+1);	
		*(mid) = '\0';
		int n1 = atoi(part);

		if(i >= 100)
			return i;
		assigns[i].image = n1;
		assigns[i++].teacher = n2;

		part = strtok(NULL, ",");
	}

	return i;
}

int get_correct_assigns(sqlite3* handler, Assign assigns[100]) {
	sqlite3_stmt* stmt;
	int ret = sqlite3_prepare(handler, "SELECT * FROM teachers", -1, &stmt, NULL);
	if(ret != SQLITE_OK)
		return -1;
	
	int i = 0;
	while(sqlite3_step(stmt) != SQLITE_DONE) {
		int id = sqlite3_column_int(stmt, 0);
		//const char* name = sqlite3_column_text(stmt, 1);
		if(sqlite3_column_text(stmt, 2) == NULL)
			continue;
		int image = sqlite3_column_int(stmt, 2);
		assigns[i].image = image;
		assigns[i++].teacher = id;
	}
	sqlite3_finalize(stmt);
	return i;
}

void insert_result(sqlite3* handler) {	
	char first_name[256] = "";
	char last_name[256] = "";
	char email[256] = "";
	char assignstr[256] = "";
	int points = 0;
	
	char line[256];
	char* l = line;
	size_t bytes = 255;
	while(getline(&l, &bytes, stdin) != -1) {
		// empty lines have only a \n
		if(strlen(line) == 1)
			continue;
		
		// remove newline char
		line[strlen(line)-1] = '\0';

		if(strstr(line, "FIRST_NAME=") == line) {
			strncpy(first_name, line+11, sizeof(first_name)); 
		} else if(strstr(line, "LAST_NAME=") == line) {
			strncpy(last_name, line+10, sizeof(last_name)); 
		} else if(strstr(line, "EMAIL=") == line) {
			strncpy(email, line+6, sizeof(email)); 
		} else if(strstr(line, "ASSIGNS=") == line) {
			strncpy(assignstr, line+8, sizeof(assignstr)); 
		}

		bytes = 255;
	}

	/*
	printf("firstname: %s\n", first_name);
	printf("lastname: %s\n", last_name);
	printf("email: %s\n", email);
	printf("results: %s\n", results);
	*/

	if(strlen(first_name) == 0) {
		printf("ERROR,NO FIRST NAME\n");
		return;
	} else if(strlen(last_name) == 0) {
		printf("ERROR,NO LAST NAME\n");
		return;
	} else if(strlen(email) == 0) {
		printf("ERROR,NO EMAIL\n");
		return;
	} else if(strlen(assignstr) == 0) {
		printf("ERROR,NO ASSIGNS\n");
		return;
	}

	Assign assigns[100];
	int assignlen = parse_assigns(assignstr, assigns);
	if(assignlen == -1) {
		printf("ERROR,INVALID ASSIGNS\n");
		return;
	}

	Assign correct[100];
	int correctlen = get_correct_assigns(handler, correct);
	if(correctlen == -1) {
		printf("ERROR,CAN'T GET CORRECT ASSIGNS\n");
		return;
	}

	int i;
	/*
	printf("Your assigns:\n");
	for(i = 0; i < assignlen; i++)
		printf("%d -> %d\n", assigns[i].image, assigns[i].teacher);
	printf("Correct assigns:\n");
	for(i = 0; i < correctlen; i++)
		printf("%d -> %d\n", correct[i].image, correct[i].teacher);
	*/

	if(!are_assigns_valid(assigns, assignlen)) {
		printf("ERROR,REDUNDANT ASSIGNS\n");
		return;
	}

	for(i = 0; i < correctlen; i++)
		if(is_assign_correct(assigns[i], correct, correctlen))
			points++;
	//printf("%d points\n", points);

	sqlite3_stmt* stmt;
	
	const char* query = "INSERT INTO results (first_name, last_name, email, results, points) VALUES(?, ?, ?, ? ,?)";
	int ret = sqlite3_prepare_v2(handler, query, strlen(query), &stmt, NULL);
	if(ret != SQLITE_OK) {
		printf("ERROR,SQLITE INSERT %d\n", ret);
		return;
	}

	sqlite3_bind_text(stmt, 1, first_name, strlen(first_name), SQLITE_STATIC);
	sqlite3_bind_text(stmt, 2, last_name, strlen(last_name), SQLITE_STATIC);
	sqlite3_bind_text(stmt, 3, email, strlen(email), SQLITE_STATIC);
	sqlite3_bind_text(stmt, 4, assignstr, strlen(assignstr), SQLITE_STATIC);
	sqlite3_bind_int(stmt, 5, points);

	ret = sqlite3_step(stmt);
	if(ret != SQLITE_DONE) {
		printf("ERROR,SQLITE INSERT %d\n", ret);
		return;
	}

	printf("OK\n");
	sqlite3_finalize(stmt);
}

void read_results(sqlite3* handler) {
	sqlite3_stmt* stmt;
	int ret = sqlite3_prepare(handler, "SELECT * FROM results ORDER BY points DESC", -1, &stmt, NULL);
	if(ret != SQLITE_OK) {
		printf("ERROR,SQLITE SELECT %d\n", ret);
		return;
	}
	printf("OK\n");
	
	while(sqlite3_step(stmt) != SQLITE_DONE) {
		int id = sqlite3_column_int(stmt, 0);
		const char* first_name = sqlite3_column_text(stmt, 1);
		const char* last_name = sqlite3_column_text(stmt, 2);
		const char* email = sqlite3_column_text(stmt, 3);
		const char* results = sqlite3_column_text(stmt, 4);
		int points = sqlite3_column_int(stmt, 5);

		printf("%dp: %s %s (%s)\n", points, first_name, last_name, email);
	}
	sqlite3_finalize(stmt);
}

int main() {
	printf("Content-Type: text/plain; charset=utf-8\n\n");

	sqlite3* handler;
	int ret = sqlite3_open_v2("quiz.sqlite", &handler, SQLITE_OPEN_READWRITE | SQLITE_OPEN_FULLMUTEX, NULL);
	if(ret != SQLITE_OK) {
		printf("ERROR,SQLITE OPEN %d\n", ret);
		return 0;
	}

	char* query = getenv("QUERY_STRING");
	if(query == NULL)
		query = "";

	if(strcmp(query, "TEACHERS") == 0) {
		read_teachers(handler);
	} else if(strcmp(query, "SEND") == 0) {
		insert_result(handler);
	} else if(strcmp(query, "RESULTS") == 0) { 
		read_results(handler);
	} else {
		printf("ERROR,INVALID PAGE\n");
	}

	sqlite3_close(handler);

	return 0;
}