push welcome ctf writeups

Author: caprinux

_posts/creation/2024-08-25-welcome-ctf-2024.md

@@ -0,0 +1,292 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+char ascii_art[] =
+
+"\e[0;33m⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢠⣤⣤⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⡀⠀⠸⠿⠿⠇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⣴⣿⡟⢀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⠁⣿⣷⠿⠃⢠⣤⣴⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠁⠀⠀⠀⣿⣏⣤⠄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣀⡈⠉⠁⠀⠀⠀⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢺⣿⣯⠆⠀⣠⣶⠿⣛⠛⠳⣦⣀⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣙⣤⣤⣼⡏⠹⠛⠋⢁⣠⣿⠋⠉⠛⠳⣦⣄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣀⣠⣴⡶⠾⣿⠟⢉⣭⡿⠛⠁⠀⠀⢰⠟⠉⠀⠀⠀⠀⠀⠀⠙⣷⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣀⣤⡾⠟⠛⠉⠀⠀⠀⣿⣾⠟⠁⠀⠀⠀⠀⠀⠘⣷⡀⠀⠀⠀⠀⠀⠀⠀⠈⢿⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⣴⠟⠋⣿⠀⠀⠀⠀⠀⠀⢰⡟⠁⠀⠀⠀⠀⠀⠀⠀⠀⠘⣷⡀⠀⠀⠀⠀⠀⠀⠀⠘⣷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⡾⠋⠁⠀⠀⣿⠀⠀⠀⠀⠀⠀⣿⣧⣿⠀⠀⢰⡷⠀⠀⠀⠀⢠⡟⠃⠀⠀⠀⠀⠀⠀⠀⠀⣿⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢠⡾⠋⠀⠀⠀⠀⠀⣿⡟⠀⠀⠀⠀⠀⢿⡏⠛⢀⠀⠙⠃⠀⠀⠀⢠⣿⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⣿⣧⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣰⡟⠀⠀⠀⠀⢰⣄⠀⠀⣰⡄⠀⠀⠀⠀⠘⢿⣄⢻⣖⡀⠀⠀⠀⠀⢸⠇⠀⠀⠀⠀⠀⠀⠀⠀⠀⣰⡟⠨⠻⣦⣀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣿⠀⠀⠀⠀⠀⠈⠙⠛⠷⢾⣧⣀⠀⠀⠀⠀⢠⣿⣧⣉⢷⠀⠀⠀⠀⢸⡆⠀⠀⠀⠀⠀⠀⠀⠀⣴⡟⠛⠛⠀⠈⠻⣦⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⣀⣿⡄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⣙⣻⣦⣴⠶⣿⡛⢻⡙⠻⢧⣄⣀⠀⠈⢿⣄⠀⠀⠀⠀⢀⣴⡾⠋⠀⠀⠀⠀⠀⠀⢹⣇⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⢀⣤⡾⠋⠉⠻⣦⣀⠀⠀⠀⠀⢀⣤⣶⣿⠛⠉⠁⠀⠀⠈⣿⡈⣿⠀⠀⠉⠙⠛⠶⠶⣽⣷⣤⣶⠞⠛⠁⠀⠀⠀⠀⠀⠀⠀⠀⣾⠻⣦⡄⠀⠀⠀⠀\n"
+"⠀⠀⠀⢀⣴⡾⠋⠁⠀⠀⠀⠀⠈⠙⠳⢶⣤⣄⣿⡵⣟⣿⢷⡄⠀⠀⠀⠀⣿⠇⣿⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣠⡾⠏⠀⠈⠻⣦⡀⠀⠀\n"
+"⢀⣤⣾⣛⣁⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⢻⣵⣯⣾⢋⣁⣤⣴⠶⠾⠛⠶⠾⠷⢶⣦⣤⣤⣤⣤⣤⣤⡤⠶⠶⠶⠶⠶⠿⠿⠛⠋⠉⠉⠀⠀⠀⠀⠀⠈⠻⣦⡀\n"
+"⠀⠉⠙⠛⣿⡛⠛⠛⠛⠳⠶⠶⠶⠶⠦⠤⢤⣤⣤⣤⣤⣽⣯⣥⣠⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣀⣄⣤⣤⣤⡤⠤⠴⢶⡾⠟⠛⠃\n"
+"⠀⠀⠀⠀⢹⣧⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠁⠀⠀⠀⠀⠀⠀⣾⠃⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⢻⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⡏⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠈⠿⠿⠿⠿⣿⠿⠿⠿⢿⡶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⠶⢶⣶⠶⢶⠶⣶⣶⣶⣶⣶⡿⠁⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢻⡇⠀⠀⢸⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣿⠀⠀⠀⣿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⣧⠀⠀⢸⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣿⠀⠀⢸⡟⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣿⡀⠀⢸⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣿⠀⠀⣼⠃⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠘⠛⠓⠚⠃⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠛⠚⠓⠛⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀\n"
+"         class was so boring, you fell fast asleep...        \n"
+"               tell me about your dreams?...                 \n\e[0m";
+
+char* notes[10];
+int note_ctr = 0;
+
+void take_note() {
+	size_t size;
+
+	if (note_ctr < 10) {
+		printf("note size: ");
+		scanf("%zu", &size);
+		getchar();
+
+		if (size > 0x100) {
+			puts("your notebook is not that big!");
+			return;
+		}
+
+		notes[note_ctr] = malloc(size);
+		printf("note content: ");
+		size_t sz = read(STDIN_FILENO, notes[note_ctr], size);
+		if (notes[note_ctr][sz-1] == '\n') {
+			notes[note_ctr][sz-1] = 0;
+		}
+		printf("you took down note #%d into your notebook!\n", note_ctr);
+		note_ctr++;
+	} else {
+		puts("your notebook ran out of space");
+		return;
+	}
+}
+
+void erase_note() {
+	unsigned int idx;
+	printf("note index to remove: ");
+	scanf("%u", &idx);
+	getchar();
+
+	if (idx < 10 && notes[idx]) {
+		free(notes[idx]);
+		notes[idx] = 0;
+		printf("note #%u is removed\n", idx);
+	} else {
+		puts("that note does not exist!");
+	}
+}
+
+void read_note() {
+	unsigned int idx;
+	printf("note index to read: ");
+	scanf("%u", &idx);
+	getchar();
+
+	if (idx < 10 && notes[idx]) {
+		printf("note #%u: %s\n", idx, notes[idx]);
+	} else {
+		puts("that note does not exist!");
+	}
+
+}
+
+void class() {
+
+	int opt;
+	int done = 1;
+
+	while(done) {
+		puts("\n1) take down a note");
+		puts("2) erase a note");
+		puts("3) read a note");
+		puts("4) go back");
+		printf("> ");
+		scanf("%d", &opt);
+		getchar();
+
+		switch(opt) {
+			case 1:
+				take_note();
+				break;
+			case 2:
+				erase_note();
+				break;
+			case 3:
+				read_note();
+				break;
+			case 4:
+				done = 0;
+				break;
+			default:
+				break;
+		}
+	}
+}
+
+typedef void func();
+func** dreams;
+size_t num_dreams;
+size_t dream_i;
+
+void dream_about_kdrama_guys() {
+	puts("oooooooooooooooooooooooooo, cute kdrama guy.......");
+}
+
+void dream_about_flag_real() {
+	char flag[100] = {0};
+	FILE *f = fopen("flag.txt", "r");
+	fread(flag, 100, sizeof(char), f);
+	fclose(f);
+	printf("and the flag is.............. %s............\n", flag);
+}
+
+void dream_about_flag_fake() {
+	printf("and the flag is.............. i forgot............\n");
+}
+
+void dream_about_valorant() {
+	puts("THWACK! THWACK! THWACK! THWACK! THWACK! ACE!......");
+}
+
+void dream_about_school() {
+	puts("and the best STUDENT award goes to...........");
+}
+
+func* pick_a_dream() {
+	int opt;
+
+	while (1) {
+		puts("\n1) dream about valorant");
+		puts("2) dream about kdrama guys");
+		puts("3) dream about school");
+		puts("4) dream about flag");
+		printf("> ");
+		scanf("%d", &opt);
+		getchar();
+
+		switch(opt) {
+			case 1:
+				return (func*)&dream_about_valorant;
+			case 2:
+				return (func*)&dream_about_kdrama_guys;
+			case 3:
+				return (func*)&dream_about_school;
+			case 4:
+				return (func*)&dream_about_flag_fake;
+			default:
+				break;
+		}
+	}
+}
+
+void add_dream() {
+	if (dreams == NULL) {
+		puts("you currently have no dreams planned.");
+		printf("how many dreams are you planning to have? ");
+		scanf("%zu", &num_dreams);
+		if (num_dreams > 100) {
+			puts("that's too many dreams to have in a single nap!");
+			num_dreams = 0;
+			return;
+		}
+		dreams = malloc(sizeof(func*) * num_dreams);
+	}
+
+	if (dream_i < num_dreams) {
+		dreams[dream_i] = pick_a_dream();
+		dream_i++;
+		printf("you currently have %zu/%zu dreams prepared!\n", dream_i, num_dreams);
+	} else {
+		puts("you have already finished planning all your dreams!");
+	}
+}
+
+void start_dreaming() {
+
+	for (size_t i = 0; i < num_dreams; i++) {
+		if (dreams[i]) {
+			((func*)(dreams[i]))();
+		} else {
+			break;
+		}
+		printf(".");
+		printf(".");
+		printf(".\n");
+	}
+
+	puts("you woke up from your dream -- 'wow what a good dream!'");
+	num_dreams = 0;
+	dream_i = 0;
+	free(dreams);
+	dreams = NULL;
+
+}
+
+void dream() {
+	int opt;
+	int done = 1;
+
+	while(done) {
+		puts("\n1) add a dream");
+		puts("2) start dreaming!");
+		puts("3) go back");
+		printf("> ");
+		scanf("%d", &opt);
+		getchar();
+
+		switch(opt) {
+			case 1:
+				add_dream();
+				break;
+			case 2:
+				start_dreaming();
+				break;
+			case 3:
+				done = 0;
+				break;
+			default:
+				break;
+		}
+	}
+
+}
+
+void menu() {
+
+	int opt;
+
+	puts("\n1) listen to class");
+	puts("2) start dreaming");
+	puts("3) exit");
+	printf("> ");
+	scanf("%d", &opt);
+	getchar();
+
+	switch(opt) {
+		case 1:
+			class();
+			break;
+		case 2:
+			dream();
+			break;
+		case 3:
+		default:
+			exit(0);
+	}
+}
+
+int main() {
+
+	setbuf(stdin, 0);
+	setbuf(stdout, 0);
+	printf("%s", ascii_art);
+	while (1) {
+		menu();
+	}
+
+}
+