1+ section .data
2+ response db 'HTTP/1.1 200 OK' , 0Dh , 0Ah , 'Content-Type: text/html' , 0Dh , 0Ah , 'Content-Length: 16' , 0Dh , 0Ah , 0Dh , 0Ah , 'ABCDABCDABCDABCD' , 0Dh , 0Ah , 0h
3+ prompt db 'Running on localhost at port: '
4+ section .bss
5+ buffer resb 255 , ; variable to store request headers
6+ socket resw 0 ; variable to store the socket number in hex, reverse bytes
7+
8+ section .text
9+ InitialiseServer:
10+ xor eax , eax
11+ xor ebx , ebx
12+ xor edi , edi
13+ xor esi , esi
14+ ;Initiliase the socket
15+ push BYTE 6 ; push 6 onto the stack (IPPROTO_TCP)
16+ push BYTE 1 ; push 1 onto the stack (SOCK_STREAM)
17+ push BYTE 2 ; push 2 onto the stack (PF_INET)
18+ mov ecx , esp ; move address of arguments into ecx
19+ mov ebx , 1 ; invoke subroutine SOCKET (1)
20+ mov eax , 102 ; invoke SYS_SOCKETCALL (kernel opcode 102)
21+ int 80h ; call the kernel
22+
23+ ;Bing the the server to the socket at localhost
24+ mov edi , eax ; move return value of SYS_SOCKETCALL into edi (file descriptor for new socket, or -1 on error)
25+ push DWORD 0x00000000 ; move 0 dec onto the stack IP ADDRESS
26+ push WORD [ socket ] ; move 9001 dec onto stack PORT
27+ push WORD 2 ; move 2 dec onto stack AF_INET
28+ mov ecx , esp ; move address of stack pointer into ecx
29+ push BYTE 16 ; move 16 dec onto stack (arguments length)
30+ push ecx ; push the address of arguments onto stack
31+ push edi ; push the file descriptor onto stack
32+ mov ecx , esp ; move address of arguments into ecx
33+ mov ebx , 2 ; invoke subroutine BIND (2)
34+ mov eax , 102 ; invoke SYS_SOCKETCALL (kernel opcode 102)
35+ int 80h ; call the kernel
36+
37+ ;Listen on the port for an encoming request
38+ push BYTE 1 ; move 1 onto stack (max queue length argument)
39+ push edi ; push the file descriptor onto stack
40+ mov ecx , esp ; move address of arguments into ecx
41+ mov ebx , 4 ; invoke subroutine LISTEN (4)
42+ mov eax , 102 ; invoke SYS_SOCKETCALL (kernel opcode 102)
43+ int 80h ; call the kernel
44+
45+ ;Accept an incoming request
46+ .accept:
47+ push BYTE 0 ; push 0 dec onto stack (address length argument)
48+ push BYTE 0 ; push 0 dec onto stack (address argument)
49+ push edi ; push the file descriptor onto stack
50+ mov ecx , esp ; move address of arguments into ecx
51+ mov ebx , 5 ; invoke subroutine ACCEPT (5)
52+ mov eax , 102 ; invoke SYS_SOCKETCALL (kernel opcode 102)
53+ int 80h ; call the kernel
54+
55+ ;Fork the server into 2 child processes, one to read the buffer, one to accept the request
56+ mov esi , eax ; move return value of SYS_SOCKETCALL into esi (file descriptor for accepted socket, or -1 on error)
57+ mov eax , 2 ; invoke SYS_FORK (kernel opcode 2)
58+ int 80h ; call the kernel
59+
60+ cmp eax , 0 ; if return value of SYS_FORK in eax is zero we are in the child process
61+ jz .read ; jmp in child process to _read
62+
63+ jmp .accept ; jmp in parent process to _accept
64+
65+ ;Read the sent request
66+ .read:
67+ mov edx , 255 ; number of bytes to read (we will only read the first 255 bytes for simplicity)
68+ mov ecx , buffer ; move the memory address of our buffer variable into ecx
69+ mov ebx , esi ; move esi into ebx (accepted socket file descriptor)
70+ mov eax , 3 ; invoke SYS_READ (kernel opcode 3)
71+ int 80h ; call the kernel
72+
73+ mov eax , buffer ; move the memory address of our buffer variable into eax for printing
74+ call sprintLF ; call our string printing function
75+
76+ ;Send the value of the request to the socket
77+ mov edx , 80 ; move 80 dec into edx (length in bytes to write)
78+ mov ecx , response ; move address of our response variable into ecx
79+ mov ebx , esi ; move file descriptor into ebx (accepted socket id)
80+ mov eax , 4 ; invoke SYS_WRITE (kernel opcode 4)
81+ int 80h ; call the kernel
82+
83+ ;Close the socket
84+ mov ebx , esi ; move esi into ebx (accepted socket file descriptor)
85+ mov eax , 6 ; invoke SYS_CLOSE (kernel opcode 6)
86+ int 80h ; call the kernel
87+ ret
88+
89+ ; Takes:
90+ ; eax: address of argv[1]
91+ ; Sets the value of the socket varibale to argv[1] in reverse byte order
92+ SetSocketFromArg:
93+ mov eax , [ eax ]
94+ push eax
95+ sub al , 0x30
96+ sub ah , 0x30
97+ shl al , 4
98+ add al , ah
99+ movzx bx , al
100+ pop eax
101+ shr eax , 16
102+ sub al , 0x30
103+ sub ah , 0x30
104+ shl al , 4
105+ add al , ah
106+ shl bx , 8
107+ and ax , 0xFF
108+ add bx , ax
109+ movzx eax , bx
110+ call GetDecimalValueFromHex
111+ xchg dh , dl
112+ mov [ socket ], dx
113+ ret
0 commit comments