re learning (27) attack and defense world toddler_regs (string function summary + cross reference)

main() function not found, find string, special string found

 Locate the location where the string appears, disassemble the code, and analyze it."

 

flag{Xp0int_1s_n1c3_but_Xp0intJNU_is_we1rd} 

Summarize

1.CP: shift+F12 displays all strings; ctrl+x finds all positions where a certain string appears

Please see the following blog for a detailed explanation:

IDA reverse notes-cross-reference analysis (shortcut key X)_ida cross-reference shortcut key_yearning for life blog-CSDN blog

chatgpt explains the benefits of cross-referencing:

2. Summarize the C language string functions:

1. gets() function
2. puts() function
3. strcat (character array 1, character array 2)—string concatenation function

The function is to connect the strings in the two character arrays, connect string 2 to the back of string 1, and put the result into character array 1

     4. strcpy (character array 1, string 2, n)—string copy function

                 The function is to copy string 2 to character array 1

     5.strcmp (character array 1, string 2)—string comparison function

      Because strings cannot be compared using the equal sign, use the strcmp function to compare! ! !

      Comparison rules: (1) If all characters are the same, the two strings are considered equal;

                        (2) If different characters appear, the comparison result of the first pair of different characters shall prevail, and the comparison result will be brought back by the function value

     6.strlen (character array)—function to measure the length of a string

Note: The string ends with '\0'!