Function at 0x51a120
Capabilities:
Validate payment card number using luhn algorithm

Disassembly:
sub esp, 0x10
push ebx
mov ebx, dword [esp + 0x1c]
push ebp
mov ebp, dword [esp + 0x30]
push esi
push edi
mov edi, dword [esp + 0x24]
mov dword [ebp], 0
mov al, byte [ebx]
cmp al, 0xa
je 0x51a697
cmp al, 0xd
je 0x51a697
mov ecx, dword [edi + 0xc4]
lea ebp, [edi + 0xc4]
mov esi, 4
lea eax, [ecx + 1]
mov dword [ebp], eax
test ecx, ecx
jne 0x51a5b1
mov dword [edi + 0xd0], ecx
mov eax, dword [edi + 0x18]
mov eax, dword [eax + 0x2ac]
mov eax, dword [eax + 0x48]
test al, 3
je 0x51a339
mov al, byte [ebx]
mov esi, ebx
test al, al
je 0x51a1a1
nop dword [eax]
cmp al, 0x20
je 0x51a199
cmp byte [esi], 9
jne 0x51a1a1
mov al, byte [esi + 1]
inc esi
test al, al
jne 0x51a190
push 5
push str.HTTP_
push esi
call fcn.0063b1a0
add esp, 0xc
test eax, eax
jne 0x51a264
movsx ecx, byte [esi + 5]
mov eax, ecx
sub eax, 0x31
je 0x51a294
sub eax, 1
je 0x51a1ed
sub eax, 1
je 0x51a1ed
push str.Unsupported_HTTP_version_in_response
push edi
call fcn.00508360
add esp, 8
mov eax, 1
pop edi
pop esi
pop ebp
pop ebx
add esp, 0x10
ret
mov al, byte [esi + 6]
cmp al, 0x20
je 0x51a1f8
cmp al, 9
jne 0x51a264
lea eax, [ecx - 0x30]
lea eax, [eax + eax*4]
add eax, eax
mov dword [edi + 0xd0], eax
mov cl, byte [esi + 7]
lea eax, [ecx - 0x30]
cmp al, 9
ja 0x51a264
mov dl, byte [esi + 8]
lea eax, [edx - 0x30]
cmp al, 9
ja 0x51a264
mov dh, byte [esi + 9]
mov al, dh
sub al, 0x30
cmp al, 9
ja 0x51a264
movsx eax, cl
lea ecx, [eax + eax*4]
movsx eax, dl
lea eax, [eax + ecx*2]
lea ecx, [eax + eax*4]
movsx eax, dh
lea eax, [eax + ecx*2]
add eax, 0xffffeb30
mov dword [edi + 0xd4], eax
mov al, byte [esi + 0xa]
cmp al, 0x20
je 0x51a416
cmp al, 9
je 0x51a416
cmp al, 0xa
jl 0x51a264
cmp al, 0xd
jle 0x51a416
push dword [esp + 0x2c]
push ebx
push edi
call fcn.00519530
add esp, 0xc
cmp eax, 1
jne 0x51a5e0
mov dword [edi + 0xd4], 0xc8
mov dword [edi + 0xd0], 0xa
jmp 0x51a416
cmp byte [esi + 6], 0x2e
jne 0x51a31e
mov al, byte [esi + 7]
cmp al, 0x30
je 0x51a2a9
cmp al, 0x31
jne 0x51a31e
mov cl, byte [esi + 8]
cmp cl, 0x20
je 0x51a2b6
cmp cl, 9
jne 0x51a31e
movsx eax, al
sub eax, 0x26
mov dword [edi + 0xd0], eax
mov cl, byte [esi + 9]
lea eax, [ecx - 0x30]
cmp al, 9
ja 0x51a31e
mov dl, byte [esi + 0xa]
lea eax, [edx - 0x30]
cmp al, 9
ja 0x51a31e
mov dh, byte [esi + 0xb]
mov al, dh
sub al, 0x30
cmp al, 9
ja 0x51a31e
movsx eax, cl
lea ecx, [eax + eax*4]
movsx eax, dl
lea eax, [eax + ecx*2]
lea ecx, [eax + eax*4]
movsx eax, dh
lea eax, [eax + ecx*2]
add eax, 0xffffeb30
mov dword [edi + 0xd4], eax
mov al, byte [esi + 0xc]
cmp al, 0x20
je 0x51a416
cmp al, 9
je 0x51a416
sub al, 0xa
cmp al, 3
jbe 0x51a416
push str.Unsupported_HTTP_1_subversion_in_response
push edi
call fcn.00508360
add esp, 8
mov eax, 1
pop edi
pop esi
pop ebp
pop ebx
add esp, 0x10
ret
test eax, 0x40000
je 0x51a5e0
mov al, byte [ebx]
mov esi, ebx
test al, al
je 0x51a361
nop dword [eax]
cmp al, 0x20
je 0x51a359
cmp byte [esi], 9
jne 0x51a361
mov al, byte [esi + 1]
inc esi
test al, al
jne 0x51a350
push 5
push str.RTSP_
push esi
call fcn.0063b1a0
add esp, 0xc
test eax, eax
jne 0x51a5e0
mov al, byte [esi + 5]
sub al, 0x30
cmp al, 9
ja 0x51a5e7
cmp byte [esi + 6], 0x2e
jne 0x51a5e7
mov al, byte [esi + 7]
sub al, 0x30
cmp al, 9
ja 0x51a5e7
mov al, byte [esi + 8]
cmp al, 0x20
je 0x51a3ac
cmp al, 9
jne 0x51a5e7
mov cl, byte [esi + 9]
lea eax, [ecx - 0x30]
cmp al, 9
ja 0x51a5e7
mov dl, byte [esi + 0xa]
lea eax, [edx - 0x30]
cmp al, 9
ja 0x51a5e7
mov dh, byte [esi + 0xb]
mov al, dh
sub al, 0x30
cmp al, 9
ja 0x51a5e7
movsx eax, cl
lea ecx, [eax + eax*4]
movsx eax, dl
lea eax, [eax + ecx*2]
lea ecx, [eax + eax*4]
movsx eax, dh
lea eax, [eax + ecx*2]
add eax, 0xffffeb30
mov dword [edi + 0xd4], eax
mov al, byte [esi + 0xc]
cmp al, 0x20
je 0x51a40c
cmp al, 9
je 0x51a40c
sub al, 0xa
cmp al, 3
ja 0x51a5e7
mov dword [edi + 0xd0], 0xb
mov ecx, dword [edi + 0xd0]
mov eax, ecx
mov esi, dword [edi + 0x18]
sub eax, 0xa
je 0x51a440
sub eax, 1
je 0x51a440
mov eax, ecx
mov ecx, 0xa
cdq
idiv ecx
mov ebp, eax
mov ecx, edx
mov eax, str.Unsupported_HTTP_version___u._d__in_response
jmp 0x51a477
mov al, byte [esi + 0x514]
test al, al
je 0x51a490
movzx ecx, al
mov eax, 0xcccccccd
mul ecx
mov eax, 0x66666667
mov ebp, edx
imul dword [edi + 0xd0]
shr ebp, 3
sar edx, 2
mov ecx, edx
shr ecx, 0x1f
add ecx, edx
cmp ecx, ebp
je 0x51a490
mov eax, str.Version_mismatch__from_HTTP__u_to_HTTP__u_
push ecx
push ebp
push eax
push edi
call fcn.00508360
add esp, 0x10
mov eax, 1
pop edi
pop esi
pop ebp
pop ebx
add esp, 0x10
ret
mov eax, dword [edi + 0xd4]
mov dword [edi + 0xd10], eax
mov eax, dword [edi + 0xd0]
mov dword [edi + 0xd18], eax
movzx eax, byte [edi + 0xd0]
mov byte [esi + 0x514], al
mov al, byte [edi + 0xced]
test al, al
je 0x51a4ca
movzx eax, al
cmp eax, dword [edi + 0xd0]
jle 0x51a4d6
mov al, byte [edi + 0xd0]
mov byte [edi + 0xced], al
mov eax, dword [edi + 0xbd0]
or eax, dword [edi + 0xbd4]
je 0x51a500
cmp byte [edi + 0xcee], 0
jne 0x51a500
cmp dword [edi + 0xd4], 0x1a0
jne 0x51a500
mov byte [edi + 0x132], 1
mov eax, dword [edi + 0xd0]
cmp eax, 0xa
jne 0x51a523
push str.HTTP_1.0__assume_close_after_body
push edi
call fcn.00508430
push 1
push esi
call fcn.0050aa20
add esp, 0x10
jmp 0x51a546
cmp eax, 0x14
je 0x51a53a
cmp dword [edi + 0xdc], 2
jne 0x51a546
cmp dword [edi + 0xd4], 0x65
jne 0x51a546
mov eax, dword [esi + 0x4e8]
mov dword [eax], 2
mov ecx, dword [edi + 0xd4]
lea eax, [ecx - 0x64]
cmp eax, 0x63
setbe al
mov byte [edi + 0x133], al
sub ecx, 0xcc
je 0x51a577
sub ecx, 0x64
jne 0x51a5a6
cmp byte [edi + 0x3b0], cl
je 0x51a577
mov byte [edi + 0xdd0], 1
mov dword [edi + 0x88], 0
mov dword [edi + 0x8c], 0
mov dword [edi + 0x90], 0
mov dword [edi + 0x94], 0
mov byte [edi + 0x133], 1
mov esi, 0xc
lea ebp, [edi + 0xc4]
push dword [esp + 0x2c]
push 0
push ebx
call fcn.00622670
add esp, 0xc
test eax, eax
je 0x51a5f4
mov eax, str.Nul_byte_in_header
push eax
push edi
call fcn.00508360
add esp, 8
mov eax, 8
pop edi
pop esi
pop ebp
pop ebx
add esp, 0x10
ret
mov byte [edi + 0x129], 0
pop edi
pop esi
pop ebp
mov eax, 8
pop ebx
add esp, 0x10
ret
mov ecx, dword [ebp]
cmp ecx, 2
jl 0x51a63b
mov al, byte [ebx]
cmp al, 0x20
je 0x51a606
cmp al, 9
jne 0x51a60b
cmp ecx, 2
jg 0x51a63b
mov ebp, dword [esp + 0x2c]
push ebp
push 0x3a
push ebx
call fcn.00622670
add esp, 0xc
test eax, eax
jne 0x51a63f
mov eax, str.Header_without_colon
push eax
push edi
call fcn.00508360
add esp, 8
mov eax, 8
pop edi
pop esi
pop ebp
pop ebx
add esp, 0x10
ret
mov ebp, dword [esp + 0x2c]
push ebp
push ebx
push edi
call fcn.00517c70
add esp, 0xc
test eax, eax
jne 0x51a712
push ebp
push ebx
push 1
push edi
call fcn.005082c0
mov eax, dword [edi + 0xd4]
add esp, 0x10
sub eax, 0x64
cmp eax, 0x64
jae 0x51a670
or esi, 0x20
push ebp
push ebx
push esi
push edi
call fcn.005095a0
add esp, 0x10
test eax, eax
jne 0x51a712
push eax
push ebp
push edi
call fcn.005172b0
add esp, 0xc
pop edi
pop esi
pop ebp
pop ebx
add esp, 0x10
ret
mov esi, dword [esp + 0x2c]
lea eax, [esi + 1]
push eax
lea eax, [esp + 0x14]
push eax
call fcn.004fb470
push esi
lea eax, [esp + 0x1c]
push ebx
push eax
call fcn.004fb430
add esp, 0x14
test eax, eax
jne 0x51a712
lea eax, [edi + 0x878]
push eax
call fcn.004fb4b0
add esp, 4
lea eax, [esp + 0x24]
push eax
push dword [esp + 0x38]
lea eax, [esp + 0x18]
push dword [esp + 0x38]
push eax
call fcn.004fb490
add esp, 4
push eax
lea eax, [esp + 0x20]
push eax
call fcn.004fb4a0
add esp, 4
push eax
push edi
call fcn.00519680
mov ecx, dword [esp + 0x3c]
mov esi, eax
add dword [ebp], ecx
lea eax, [esp + 0x28]
push eax
call fcn.004fb440
add esp, 0x1c
mov eax, esi
pop edi
pop esi
pop ebp
pop ebx
add esp, 0x10
ret