# PURPOSE: a http server # # AUTHOR: Andreas Jaggi # # All rights reserved. .equ OUTPUT, 1 .equ REQUIRED_PERM, 0x124 # = 0444 .equ SENDFILE_SIZE, 4096 .section .data socket_args: .long 2,1,6 # AF_INET, SOCK_STREAM, IPPROTO_TCP local_sockaddr: .byte 0x00 # AF_INET .byte 0x02 .byte 0x1f # port: 8080 (80 = 0x0050) .byte 0x90 .byte 0x7f # IP: 127.0.0.1 .byte 0x00 .byte 0x00 .byte 0x01 .long 0x0,0x0 # zero-fill bind_args: .long 0 .long local_sockaddr .long 0x10 listen_args: .long 0,4 accept_remote_addr: #22 bytes .long 0,0,0,0,0 .byte 0 accept_remote_addr_len: .long 22 accept_args: .long 0,accept_remote_addr,accept_remote_addr_len recv_args: .long 0,recv_buffer,RECV_BUFFER_SIZE,0 shutdown_args: .long 0,2 CHR_SPACE: .ascii " " CHR_NEWLINE: .ascii "\n" CHR_SLASH: .ascii "/" CHR_QUESTIONMARK: .ascii "?" CHR_PERCENT: .ascii "%" CHR_DOT: .ascii "." INDEX_HTML: .ascii "index.html\0" serving_msg: .ascii "Serving file " .equ serving_msg_len, 13 resp_200: .ascii "HTTP/1.0 200 OK\n" .equ resp_200_len, 16 resp_logo: .ascii "Server: asm80\n" .equ resp_logo_len, 14 resp_400: .ascii "HTTP/1.0 400 Bad request\n" .equ resp_400_len,25 resp_403: .ascii "HTTP/1.0 403 Forbidden\n" .equ resp_403_len, 23 resp_404: .ascii "HTTP/1.0 404 File not found\n" .equ resp_404_len, 28 resp_414: .ascii "HTTP/1.0 414 Request URL too long\n" .equ resp_414_len, 34 resp_501: .ascii "HTTP/1.0 501 Not implemented\n" .equ resp_501_len, 29 # syscall interrupt .equ SYSCALL, 0x80 # syscalls .equ EXIT, 1 .equ READ, 3 .equ WRITE, 4 .equ OPEN, 5 .equ CLOSE, 6 .equ SOCKETCALL, 102 .equ STAT, 106 .equ SENDFILE, 187 # socketcall calls .equ SYS_SOCKET, 1 .equ SYS_BIND, 2 .equ SYS_LISTEN, 4 .equ SYS_ACCEPT, 5 .equ SYS_SEND, 9 .equ SYS_RECV, 10 .equ SYS_SHUTDOWN, 13 .equ O_RDONLY, 0 .equ EACCES,-13 .equ __S_IFREG, 0x8000 .equ __S_IFDIR, 0x4000 .section .bss .equ RECV_BUFFER_SIZE, 4096 .lcomm recv_buffer, RECV_BUFFER_SIZE .equ STAT_BUF_SIZE, 88 .lcomm stat_buf, STAT_BUF_SIZE .section .text .globl _start _start: #sock = socket(AF_INET=2, SOCK_STREAM=1, IPPROTO_TCP=6) movl $SOCKETCALL, %eax #socketcall movl $SYS_SOCKET, %ebx #SYS_SOCKET movl $socket_args, %ecx #AF_INET,SOCK_STREAM,IPROTO_TCP int $SYSCALL pushl %eax #put socket on stack cmpl $0, %eax je socket_error_end movl $0, %ebx subl %eax, %ebx movl $EXIT, %eax socket_error_end: #bind(sock, local_addr, sizeof(local_addr)); movl $SOCKETCALL, %eax #socketcall movl $SYS_BIND, %ebx #SYS_BIND movl (%esp), %edx #put socket in args movl %edx, (bind_args) movl $bind_args, %edx #put local_sockaddr in args movl $local_sockaddr, 4(%edx) movl $bind_args, %ecx int $SYSCALL cmpl $0, %eax je bind_error_end movl $0, %ebx subl %eax, %ebx movl $EXIT, %eax int $SYSCALL bind_error_end: #listen(sock, x?); movl $SOCKETCALL, %eax #socketcall movl $SYS_LISTEN, %ebx #SYS_LISTEN movl (%esp), %edx #put socket in args movl %edx, (listen_args) movl $listen_args, %ecx int $SYSCALL cmpl $0, %eax je listen_error_end movl $0, %ebx subl %eax, %ebx movl $EXIT, %eax int $SYSCALL listen_error_end: pushl $0xdeadbeaf #put nonsense on stack sock_loop: addl $4, %esp #pop stack (e.g. free nonsense or sock2) #while ( ( sock2 = accept(sock, remote_host_addr, max_remote_host_addr_len) ) > -1 ) movl $SOCKETCALL, %eax #socketcall movl $SYS_ACCEPT, %ebx #SYS_ACCEPT movl (%esp), %edx #put socket in args movl %edx, (accept_args) movl $accept_args, %ecx int $SYSCALL cmpl $1, %eax jl end_sock pushl %eax #put sock2 on stack # disable fork for gdb # movl $2, %eax #fork # int $SYSCALL # # cmpl $0, %eax # jne sock_loop sock2_loop: #n = recv(sock2, buff, len, flags) movl $SOCKETCALL, %eax #socketcall movl $SYS_RECV, %ebx #SYS_RECV movl (%esp), %edx #put sock2 in args movl %edx, (recv_args) movl $recv_args, %ecx int $SYSCALL #cmpl $1, %eax cmpl $14, %eax #close connection on error or when < 14 bytes received jl end_sock2 movl $recv_buffer, %ebx # %ebx points to buffer addl $recv_buffer, %eax # %eax now points 1 byte behind buffer # search the first space in the first line of the request (where the GET or POST is located) # in order to extract the requested filename # the line should look like one of these: # POST / HTTP/1.x # GET / HTTP/1.x # POST /foo HTTP/1.x # GET /foo HTTP/1.x # etc. rq_space_search_loop: incl %ebx cmpl %eax, %ebx # when end of buffer is reached, send 400 je quit_with_400 movb (%ebx), %dl cmpb (CHR_NEWLINE), %dl # when there's no space in the first line, send 414 je quit_with_414 cmpb (CHR_SPACE), %dl jne rq_space_search_loop incl %ebx # %ebx now points to begin of REQUEST_STRING # search the second space movl %ebx, %ecx decl %ecx rq_qm_search_loop: incl %ecx cmpl %eax, %ecx # when end of buffer is reached, send 414 je quit_with_414 movb (%ecx), %dl cmpb (CHR_NEWLINE), %dl # when there's a linebreak before the questionmark (or space), send 400 je quit_with_400 cmpb (CHR_SPACE), %dl # when there's a space before the questionmark, treat it as questionmark (e.g. assume that there is no questionmark) je end_rq_qm_search_loop cmpb (CHR_QUESTIONMARK), %dl jne rq_qm_search_loop end_rq_qm_search_loop: # %ecx now points 1 byte behind REQUEST_STRING (XXX: this is wrong when there is a SPACE in the request string!!!) pushl %eax # backup registers pushl %ebx pushl %ecx pushl %edx # write "Serving file xxx\n" on output movl $WRITE, %eax movl $OUTPUT, %ebx movl $serving_msg, %ecx movl $serving_msg_len, %edx int $SYSCALL movl $WRITE, %eax movl $OUTPUT, %ebx movl 8(%esp), %ecx movl 4(%esp), %edx subl 8(%esp), %edx int $SYSCALL movl $WRITE, %eax movl $OUTPUT, %ebx movl $CHR_NEWLINE, %ecx movl $1, %edx int $SYSCALL # restore registers: popl %edx popl %ecx # %ecx points 1 byte behind REQUEST_STRING popl %ebx # %ebx points to the begin of REQUEST_STRING popl %eax # %eax points 1 byte behind buffer movb $0, (%ecx) # NULL-terminate REQUEST_STRING remove_leading_slash_loop: incl %ebx # get rid of the leading slash cmpl %ebx, %eax # if end of buffer reached (e.g. some jerk sending only slashes), je end_sock2 # close connection movb (%ebx), %dl cmpb (CHR_SLASH), %dl je remove_leading_slash_loop cmpl %ecx, %ebx # if no filename given (/) serve index.html jge default_index_html movl %ebx, %esi # src pointer to REQUEST_STRING movl %ebx, %edi # dst pointer to REQUEST_STRING (yes, we do in-place conversion) url_copy_loop: movl $0, %edx movb (%esi), %dl # get next char from REQUEST_STRING cmpb %dl, (CHR_PERCENT) # urldecode if % found jne end_urldecode_chr movl $0, %edx incl %esi movb (%esi), %dl cmpb $48, %dl jl quit_with_400 cmpb $57, %dl jg end_decode_09 subl $48, %edx # 0-9 jmp calc_second_byte end_decode_09: cmpb $65, %dl jl quit_with_400 cmpb $70, %dl jg end_decode_AZ subl $55, %edx # A-Z jmp calc_second_byte end_decode_AZ: cmpb $97, %dl jl quit_with_400 cmpb $102, %dl jg quit_with_400 subl $87, %edx # a-z calc_second_byte: movl $16, %eax imull %edx, %eax movl $0, %edx incl %esi movb (%esi), %dl cmpb $48, %dl jl quit_with_400 cmpb $57, %dl jg end_decode2_09 subl $48, %edx # 0-9 jmp end_decode end_decode2_09: cmpb $65, %dl jl quit_with_400 cmpb $70, %dl jg end_decode2_AZ subl $55, %edx # A-Z jmp end_decode end_decode2_AZ: cmpb $97, %dl jl quit_with_400 cmpb $102, %dl jg quit_with_400 subl $87, %edx # a-z end_decode: addl %edx, %eax movl %eax, %edx end_urldecode_chr: movb %dl, (%edi) # write 'translated' char incl %esi # increase src pointer incl %edi # increase dst pointer cmpl %ecx, %esi # check REQUEST_STRING boundary jl url_copy_loop # treat next char of REQUEST_STRING end_url_copy: movl $0, (%edi) # NULL-terminate REQUEST_STRING (for stat) movl %ebx, %esi # search for '..' and return 403 if found double_dot_search_loop: movb (%esi), %dl cmpb %dl, (CHR_DOT) # first dot found je first_dot_found incl %esi cmpl %ecx, %esi jge end_double_dot_search_loop jmp double_dot_search_loop first_dot_found: movb (%esi), %dl cmpb %dl, (CHR_DOT) # second dot found jne double_dot_search_loop jmp quit_with_403 # -> 403 end_double_dot_search_loop: # TODO: sanity check of REQUEST_STRING cmpl %ebx, %ecx # if no filename given (/) serve index.html jg default_index_html_end default_index_html: movl $INDEX_HTML, %ebx jmp load_file default_index_html_end: load_file: # assumes pointer to filename in %ebx, null-terminated movl $STAT, %eax # stat file movl $stat_buf, %ecx int $SYSCALL cmpl $EACCES, %eax # when stat gives EACCES -> 403 je quit_with_403 cmpl $0,%eax # all other stat errors -> 404 jl quit_with_404 movl $stat_buf, %ecx movl 8(%ecx), %eax # get mode bits from stat structure # stat struct: # st_dev, 32bits ? # st_ino, 32bits ? # st_mode, 32bits ? # ... movl %eax, %ecx # if file has not the required permissions -> 403 andl $REQUIRED_PERM, %ecx cmpl $REQUIRED_PERM, %ecx jne quit_with_403 movl %eax, %ecx # if file is directory, call serve_dir andl $__S_IFDIR, %ecx cmpl $__S_IFDIR, %ecx je serve_dir movl %eax, %ecx # if file is not a regular file -> 403 andl $__S_IFREG, %ecx cmpl $__S_IFREG, %ecx jne quit_with_403 # open file (filename is in %ebx) movl $OPEN, %eax movl $O_RDONLY, %ecx movl $0777, %edx int $SYSCALL cmpl $0, %eax jl quit_with_404 # TODO: is 404 the appropriate error? pushl %eax # put fp on stack movl $WRITE, %eax # send 200 response movl 4(%esp), %ebx # load sock2 from stack movl $resp_200, %ecx movl $resp_200_len, %edx int $SYSCALL movl $WRITE, %eax # send Server: asm80 movl 4(%esp), %ebx # load sock2 from stack movl $resp_logo, %ecx movl $resp_logo_len, %edx int $SYSCALL movl $WRITE, %eax # send newline to end header movl 4(%esp), %ebx # load sock2 from stack movl $CHR_NEWLINE, %ecx movl $1, %edx int $SYSCALL sendfile_loop: movl $SENDFILE, %eax movl 4(%esp), %ebx # load sock2 from stack movl (%esp), %ecx # load fp from stack movl $0, %edx movl $SENDFILE_SIZE, %esi int $SYSCALL cmpl $0, %eax jl close_file cmpl $SENDFILE_SIZE, %eax je sendfile_loop close_file: popl %ebx # restore stack (free fp) movl $CLOSE, %eax int $SYSCALL jmp end_sock2 jmp end_serve_dir serve_dir: # TODO: implement this movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_501, %ecx movl $resp_501_len, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_logo, %ecx movl $resp_logo_len, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $CHR_NEWLINE, %ecx movl $1, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_501, %ecx movl $resp_501_len, %edx int $SYSCALL jmp end_sock2 end_serve_dir: jmp end_quit_with_400 quit_with_400: movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_400, %ecx movl $resp_400_len, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_logo, %ecx movl $resp_logo_len, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $CHR_NEWLINE, %ecx movl $1, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_400, %ecx movl $resp_400_len, %edx int $SYSCALL end_quit_with_400: jmp end_quit_with_403 quit_with_403: movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_403, %ecx movl $resp_403_len, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_logo, %ecx movl $resp_logo_len, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $CHR_NEWLINE, %ecx movl $1, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_403, %ecx movl $resp_403_len, %edx int $SYSCALL jmp end_sock2 end_quit_with_403: jmp end_quit_with_404 quit_with_404: movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_404, %ecx movl $resp_404_len, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_logo, %ecx movl $resp_logo_len, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $CHR_NEWLINE, %ecx movl $1, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_404, %ecx movl $resp_404_len, %edx int $SYSCALL jmp end_sock2 end_quit_with_404: jmp end_quit_with_414 quit_with_414: movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_414, %ecx movl $resp_414_len, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_logo, %ecx movl $resp_logo_len, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $CHR_NEWLINE, %ecx movl $1, %edx int $SYSCALL movl $WRITE, %eax movl (%esp), %ebx # load sock2 from stack movl $resp_414, %ecx movl $resp_414_len, %edx int $SYSCALL jmp end_sock2 end_quit_with_414: end_sock2: #shutdown(sock2, SHUT_RDWR) movl $SOCKETCALL, %eax #socketcall movl $SYS_SHUTDOWN, %ebx #SYS_SHUTDOWN movl (%esp), %edx #put sock2 in args movl %edx, (shutdown_args) movl $shutdown_args, %ecx int $SYSCALL #close(sock2) movl $CLOSE, %eax #close movl (%esp), %ebx #put sock2 in %ebx int $SYSCALL jmp sock_loop end_sock: #shutdown(sock, SHUT_RDWR) movl $SOCKETCALL, %eax #socketcall movl $SYS_SHUTDOWN, %ebx #SYS_SHUTDOWN movl (%esp), %edx #put sock in args movl %edx, (shutdown_args) movl $shutdown_args, %ecx int $SYSCALL #close(sock) movl $CLOSE, %eax #close movl (%esp), %ebx #put sock in %ebx int $SYSCALL addl $4, %esp # restore stack (free sock) movl $EXIT, %eax #exit(0) movl $0, %ebx int $SYSCALL