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tleydxdy
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custom elf header
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‎asm.sh

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#!/bin/sh
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nasm -f bin -o httpd httpd.asm

‎httpd.asm

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; elf header see http://muppetlabs.com/~breadbox/software/tiny/teensy.html
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BITS 64
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org 0x08048000
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ehdr: ; Elf32_Ehdr
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db 0x7F, "ELF", 2, 1, 1, 0 ; e_ident
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?_033:
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db "usage: ", 0
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dw 2 ; e_type
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dw 62 ; e_machine
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dd 1 ; e_version
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dq _start ; e_entry
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dq phdr - $$ ; e_phoff
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?_034:
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db " port fi" ; e_shoff
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db "le", 10, 0 ; e_flags
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dw ehdrsize ; e_ehsize
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dw phdrsize ; e_phentsize
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phdr: ; Elf32_Phdr
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dd 1 ; e_phnum ; p_type
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; e_shentsize
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dd 5 ; e_shnum ; p_flags
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; e_shstrndx
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ehdrsize equ $ - ehdr
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dq 0 ; p_offset
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dq $$ ; p_vaddr
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dq $$ ; p_paddr
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dq filesize ; p_filesz
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dq filesize ; p_memsz
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dq 0x1000 ; p_align
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phdrsize equ $ - phdr
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_start:
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xor rbp, rbp
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xor r9, r9
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pop rdi
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mov rsi, rsp
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push r14
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push r13
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push r12
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push rbp
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push rbx
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mov rbx, rsi
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sub rsp, 8224
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cmp edi, 3
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jnz ?_004
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mov rcx, qword [rsi+8H]
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xor eax, eax
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?_002: movsx dx, byte [rcx]
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test dl, dl
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jz ?_003
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lea esi, [rdx-30H]
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cmp sil, 9
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ja ?_004
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imul eax, eax, 10
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inc rcx
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lea eax, [rax+rdx-30H]
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jmp ?_002
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?_003: xchg al, ah
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test ax, ax
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jnz ?_007
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?_004: mov rbp, qword [rbx]
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mov edx, 7
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mov edi, 1
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lea rsi, [rel ?_033]
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call ?_027
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mov rdx, rbp
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?_005: cmp byte [rdx], 0
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jz ?_006
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inc rdx
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jmp ?_005
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?_006: sub rdx, rbp
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mov rsi, rbp
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mov edi, 1
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call ?_027
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mov edx, 11
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mov edi, 1
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lea rsi, [rel ?_034]
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call ?_027
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mov edi, 1
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call ?_017
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xor eax, eax
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?_007: xorps xmm0, xmm0
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lea rsi, [rsp+0CH]
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lea rdi, [rsp+10H]
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mov edx, 4
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movups oword [rsp+10H], xmm0
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mov dword [rsp+0CH], 1
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mov word [rsp+10H], 2
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mov word [rsp+12H], ax
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call ?_029
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mov r13d, eax
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?_008: xor edx, edx
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xor esi, esi
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mov edi, r13d
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call ?_023
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mov ebp, eax
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test eax, eax
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js ?_008
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xor eax, eax
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call ?_018
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mov r12d, eax
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test eax, eax
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jnz ?_008
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mov r14, qword [rbx+10H]
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lea r13, [rsp+20H]
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?_009: mov edx, 8192
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mov rsi, r13
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mov edi, ebp
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call ?_028
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mov ebx, eax
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test eax, eax
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jle ?_010
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mov edx, ebx
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mov rsi, r13
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mov edi, 1
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call ?_027
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movsxd rax, ebx
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lea rax, [r13+rax-3H]
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cmp ebx, 2
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jg ?_011
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?_010: xor esi, esi
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mov rdi, r14
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call ?_026
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mov ebx, eax
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test eax, eax
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jns ?_012
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mov edx, 39
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lea rsi, [rel ?_035]
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mov edi, ebp
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call ?_027
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jmp ?_015
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?_011: cmp byte [rax], 10
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jnz ?_009
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cmp byte [rax+1H], 13
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jnz ?_009
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cmp byte [rax+2H], 10
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jnz ?_009
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jmp ?_010
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?_012: mov edx, 19
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lea rsi, [rel ?_036]
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mov edi, ebp
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call ?_027
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?_013: mov edx, 8192
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mov rsi, r13
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mov edi, ebx
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call ?_028
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mov edx, eax
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test eax, eax
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jle ?_014
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mov rsi, r13
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mov edi, ebp
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call ?_027
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test eax, eax
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jns ?_013
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jmp ?_015
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?_014: mov edi, ebp
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mov esi, 2
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call ?_022
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mov edi, ebp
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call ?_025
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jmp ?_016
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?_015: mov r12d, 1
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?_016: add rsp, 8224
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mov eax, r12d
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pop rbx
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pop rbp
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pop r12
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pop r13
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pop r14
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call ?_017
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?_017:
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add r9, 3
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?_018: add r9, 3
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?_019: add r9, 4
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?_020: add r9, 1
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?_021: add r9, 1
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?_022: add r9, 5
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?_023: add r9, 2
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?_024: add r9, 38
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?_025: add r9, 1
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?_026: add r9, 1
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?_027: add r9, 1
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?_028: mov r10, rcx
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mov rax, r9
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xor r9, r9
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syscall
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ret
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?_029:
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push r13
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mov r13, rsi
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mov esi, 1
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push r12
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push rbp
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mov rbp, rdi
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mov edi, 2
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sub rsp, 16
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mov dword [rsp+0CH], edx
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mov edx, 6
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call ?_024
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mov r8d, dword [rsp+0CH]
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test eax, eax
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mov r12d, eax
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jns ?_031
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?_030: mov edi, 1
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call ?_017
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jmp ?_032
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?_031: mov rcx, r13
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mov edx, 2
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mov esi, 1
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mov edi, eax
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call ?_019
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test eax, eax
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jnz ?_030
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mov edx, 16
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mov rsi, rbp
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mov edi, r12d
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call ?_021
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test eax, eax
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jnz ?_030
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mov esi, 10
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mov edi, r12d
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call ?_020
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test eax, eax
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jnz ?_030
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?_032: add rsp, 16
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mov eax, r12d
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pop rbp
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pop r12
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pop r13
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ret
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?_035:
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db "HTTP/1.1 404 Not Found"
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db 0DH, 0AH, 0DH, 0AH
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db "404 Not Found", 0
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?_036:
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db "HTTP/1.1 200 OK"
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db 0DH, 0AH, 0DH, 0AH, 0
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filesize equ $ - $$

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