kolibrios-fun/programs/develop/libraries/network/network.asm

format MS COFF

public @EXPORT as 'EXPORTS'

include '../../../struct.inc'
include '../../../proc32.inc'
include '../../../macros.inc'
purge section,mov,add,sub

include '../../../network.inc'

section '.flat' code readable align 16

;;===========================================================================;;
lib_init: ;//////////////////////////////////////////////////////////////////;;
;;---------------------------------------------------------------------------;;
;? Library entry point (called after library load)                           ;;
;;---------------------------------------------------------------------------;;
;> eax = pointer to memory allocation routine                                ;;
;> ebx = pointer to memory freeing routine                                   ;;
;> ecx = pointer to memory reallocation routine                              ;;
;> edx = pointer to library loading routine                                  ;;
;;---------------------------------------------------------------------------;;
;< eax = 1 (fail) / 0 (ok) (library initialization result)                   ;;
;;===========================================================================;;
        mov     [mem.alloc], eax
        mov     [mem.free], ebx
        mov     [mem.realloc], ecx
        mov     [dll.load], edx
        mov     [DNSrequestID], 1
        xor     eax, eax
        ret

;;===========================================================================;;
;; in_addr_t __stdcall inet_addr(__in const char* hostname);                 ;;
inet_addr:                                                                   ;;
;;---------------------------------------------------------------------------;;
;? Convert the string from standard IPv4 dotted notation to integer IP addr. ;;
;;---------------------------------------------------------------------------;;
;> first parameter = host name                                               ;;
;;---------------------------------------------------------------------------;;
;< eax = IP address on success / -1 on error                                 ;;
;;===========================================================================;;
; 0. Save used registers for __stdcall.
        push    ebx esi edi
        mov     esi, [esp+16]   ; esi = hostname
; 1. Check that only allowed symbols are present.
; (hex digits, possibly letters 'x'/'X' and up to 3 dots)
        push    esi
        xor     ecx, ecx
.calcdots_loop:
; loop for all characters in string
        lodsb
; check for end of string
        cmp     al, 0
        jz      .calcdots_loop_done
; check for dot
        cmp     al, '.'
        jz      .dot
; check for digit
        sub     al, '0'
        cmp     al, 9
        jbe     .calcdots_loop
; check for hex letter
        sub     al, 'A' - '0'   ; 'A'-'F' -> 0-5, 'a'-'f' -> 20h-25h
        and     al, not 20h
        cmp     al, 'F' - 'A'
        jbe     .calcdots_loop
; check for 'x'/'X'
        cmp     al, 'X' - 'A'
        jz      .calcdots_loop
        jmp     .fail.pop
.dot:
        inc     ecx
        jmp     .calcdots_loop
.calcdots_loop_done:
        cmp     ecx, 4
        jae     .fail.pop
; 2. The name can be valid dotted name; try to convert, checking limit
        pop     esi
        xor     edi, edi        ; edi = address
        push    0xFFFFFFFF
        pop     edx             ; edx = mask for rest of address
; 2a. Convert name except for last group.
        jecxz   .ip_convert_2b
.ip_convert_2a:
        push    ecx
        mov     ecx, 0xFF       ; limit for all groups except for last
        call    .get_number
        pop     ecx
        jc      .fail
        cmp     byte [esi-1], '.'
        jnz     .fail
        shl     edi, 8
        shr     edx, 8
        add     edi, eax
        loop    .ip_convert_2a
; 2b. Convert last group.
.ip_convert_2b:
        mov     ecx, edx
        call    .get_number
        jc      .fail
        cmp     byte [esi-1], 0
        jnz     .fail
@@:
        shl     edi, 8
        shr     edx, 8
        jnz     @b
        add     edi, eax
; 2c. Convert to network byte order.
        bswap   edi
; 3. Set return value, restore used registers and return.
        xchg    eax, edi
.ret:
        pop     edi esi ebx
        ret     4
; 4. On error, return -1.
.fail.pop:
        pop     esi
.fail:
        push    -1
        pop     eax
        jmp     .ret

;;===========================================================================;;
;; Internal auxiliary function for IP parsing.                                        ;;
.get_number:                                                                 ;;
;;---------------------------------------------------------------------------;;
;? Converts string to number.                                                ;;
;;---------------------------------------------------------------------------;;
;> esi -> string                                                             ;;
;> ecx = limit for number                                                    ;;
;;---------------------------------------------------------------------------;;
;< eax = number                                                              ;;
;< CF set on error (too big number) / cleared on success                     ;;
;< esi -> end of number representation                                       ;;
;;===========================================================================;;
; 0. Save edx, which is used in caller.
        push    edx
; 1. Initialize number, zero eax so that lodsb gets full dword.
        xor     eax, eax
        xor     edx, edx
; 2. Get used numeral system: 0x = hex, otherwise 0 = octal, otherwise decimal
        push    10
        pop     ebx
        lodsb
        cmp     al, '0'
        jnz     .convert
        push    8
        pop     ebx
        lodsb
        cmp     al, 'x'
        jnz     .convert
        add     ebx, ebx
; 3. Loop while digits are encountered.
.convert:
; 4. Convert digit from text representation to binary value.
        or      al, 20h ; '0'-'9' -> '0'-'9', 'A'-'F' -> 'a'-'f'
        sub     al, '0'
        cmp     al, 9
        jbe     .digit
        sub     al, 'a' - '0'
        cmp     al, 'f' - 'a'
        ja      .convert_done
        add     al, 10
.digit:
; 5. Digit must be less than base of numeral system.
        cmp     eax, ebx
        jae     .convert_done
; 6. Advance the number.
        imul    edx, ebx
        add     edx, eax
        cmp     edx, ecx
        ja      .gn_error
; 3b. Continue loop.
        lodsb
        jmp     .convert
.convert_done:
; 7. Invalid character, number converted, return success.
        xchg    eax, edx
        pop     edx
        clc
        ret
.gn_error:
; 8. Too big number, return error.
        pop     edx
        stc
        ret

;;===========================================================================;;
;; char* __stdcall inet_ntoa(struct in_addr in);                             ;;
inet_ntoa:                                                                   ;;
;;---------------------------------------------------------------------------;;
;? Convert the Internet host address to standard IPv4 dotted notation.       ;;
;;---------------------------------------------------------------------------;;
;> first parameter = host address                                            ;;
;;---------------------------------------------------------------------------;;
;< eax = pointer to resulting string (in static buffer)                      ;;
;;===========================================================================;;
; 0. Save used registers for __stdcall.
        push    ebx esi edi
        mov     bl, 0xCD        ; constant for div 10
; 1. Write octet 4 times.
        mov     edi, .buffer
        mov     edx, [esp+16]   ; eax = in
        mov     al, dl
        call    .write
        mov     al, dh
        shr     edx, 16
        call    .write
        mov     al, dl
        call    .write
        mov     al, dh
        call    .write
; 2. Replace final dot with terminating zero.
        mov     byte [edi-1], 0
; 3. Restore used registers, set result value and return.
        pop     edi esi ebx
        mov     eax, .buffer
        ret     4

.write:
        movzx   esi, al
        mul     bl
        add     esi, ('.' shl 8) + '0'
        shr     ah, 3   ; ah = al / 10
        movzx   ecx, ah
        add     ecx, ecx
        lea     ecx, [ecx*5]
        sub     esi, ecx        ; lobyte(esi) = al % 10, hibyte(esi) = '.'
        test    ah, ah
        jz      .1digit
        cmp     ah, 10
        jb      .2digit
        cmp     ah, 20
        sbb     cl, cl
        add     cl, '2'
        mov     byte [edi], cl
        movzx   ecx, cl
        lea     ecx, [ecx*5]
        sub     ah, cl
        sub     ah, cl
        add     ah, ('0'*11) and 255
        mov     byte [edi+1], ah
        mov     word [edi+2], si
        add     edi, 4
        ret
.2digit:
        add     ah, '0'
        mov     byte [edi], ah
        mov     word [edi+1], si
        add     edi, 3
        ret
.1digit:
        mov     word [edi], si
        add     edi, 2
        ret

struct __gai_reqdata
        socketnum  dd      ?
; external code should not look on rest of this structure,
; it is internal for getaddrinfo_start/process/abort
        reqid           dw      ?       ; DNS request ID
        socktype        db      ?       ; SOCK_* or 0 for any
                        db      ?
        service         dd      ?
        flags           dd      ?
        reserved        rb      16
ends

;;===========================================================================;;
;; int __stdcall getaddrinfo(__in const char* hostname,                      ;;
;;                           __in const char* servname,                      ;;
;;                           __in const struct addrinfo* hints,              ;;
;;                           __out struct addrinfo **res);                   ;;
getaddrinfo:                                                                 ;;
;;---------------------------------------------------------------------------;;
;? Get a list of IP addresses and port numbers for given host and service    ;;
;;---------------------------------------------------------------------------;;
;> first parameter (optional) = host name                                    ;;
;> second parameter (optional) = service name (decimal number for now)       ;;
;> third parameter (optional) = hints for socket type                        ;;
;> fourth parameter = pointer to result (head of L1-list)                    ;;
;;---------------------------------------------------------------------------;;
;< eax = 0 on success / one of EAI_ codes on error                           ;;
;;===========================================================================;;
; 0. Save used registers for __stdcall.
        push    ebx esi edi
        mov     edi, [esp+28]   ; edi = res
; 1. Create and send DNS packet.
        sub     esp, sizeof.__gai_reqdata       ; reserve stack place (1)
        push    esp             ; fifth parameter = pointer to (1)
        push    edi             ; fourth parameter = res
        push    dword [esp+32+sizeof.__gai_reqdata]     ; third parameter = hints
        push    dword [esp+32+sizeof.__gai_reqdata]     ; second parameter = servname
        push    dword [esp+32+sizeof.__gai_reqdata]     ; first parameter = hostname
        call    getaddrinfo_start
        test    eax, eax
        jns     .ret    ; if name resolved without network activity, return
; 2. Wait for DNS reply.
; 2a. Ignore all events except network stack.
        mcall   40, EVM_STACK
        push    eax     ; save previous event mask (2)
; 2b. Get upper limit for wait time. Use timeout = 5 seconds.
        mcall   26, 9   ; get time stamp
        xchg    esi, eax        ; save time stamp to esi
        mov     ebx, 500        ; start value for timeout
        add     esi, ebx
.wait:
; 2c. Wait for event with timeout.
        mcall   23      ; wait for event - must be stack event
; 2d. Check for timeout.
        test    eax, eax
        jz      .timeout
; 3. Got packet. Call processing function.
        lea     eax, [esp+4]
        push    edi     ; second parameter: pointer to result
        push    eax     ; first parameter: pointer to reqdata
        call    getaddrinfo_process
; 4. Test whether wait loop must be continued.
        test    eax, eax
        jns     .ret.restore
; 2e. Recalculate timeout value.
        mcall   26, 9
        mov     ebx, esi
        sub     ebx, eax
; 2f. Check that time is not over; if not, continue wait loop
        cmp     ebx, 500
        jbe     .wait
.timeout:
; 5. Timeout: abort and return error
        lea     eax, [esp+4]    ; pointer to (1)
        push    eax
        call    getaddrinfo_abort
        and     dword [edi], 0
        push    EAI_AGAIN
        pop     eax
.ret.restore:
; 6. Restore event mask.
        pop     ebx     ; get event mask (2)
        push    eax     ; save return code (3)
        mcall   40
        pop     eax     ; restore return code (3)
.ret:
; 7. Restore stack pointer, used registers and return.
        add     esp, sizeof.__gai_reqdata       ; undo (1)
        pop     edi esi ebx
        ret     16

;;===========================================================================;;
;; int __stdcall getaddrinfo_start(__in const char* hostname,                ;;
;;                                 __in const char* servname,                ;;
;;                                 __in const struct addrinfo* hints,        ;;
;;                                 __out struct addrinfo **res,              ;;
;;                                 __out struct __gai_reqdata* reqdata);     ;;
getaddrinfo_start:                                                           ;;
;;---------------------------------------------------------------------------;;
;? Initiator for getaddrinfo, sends DNS request                              ;;
;;---------------------------------------------------------------------------;;
;> first 4 parameters same as for getaddrinfo                                ;;
;> last parameter = pointer to buffer for __gai_reqdata, must be passed to   ;;
;>                  getaddrinfo_process as is                                ;;
;;---------------------------------------------------------------------------;;
;< eax = <0 if wait loop must be entered / 0 on success / EAI_* on error     ;;
;;===========================================================================;;
;; Known limitations:                                                        ;;
;; 1. No support for TCP connections =>                                      ;;
;; 1a. Long replies will be truncated, and not all IP addresses will be got. ;;
;; 2. No support for iterative resolving =>                                  ;;
;; 2a. In theory may fail with some servers.                                 ;;
;; 3. Assumes that domain for relative names is always root, ".".            ;;
;; 4. Does not support lookup of services by name,                           ;;
;;    only decimal representation is supported.                              ;;
;; 5. Assumes that IPv4 is always configured, so AI_ADDRCONFIG has no effect.;;
;;===========================================================================;;
; 0. Create stack frame and save used registers for __stdcall.
        push    ebx esi edi
        push    ebp
        mov     ebp, esp
virtual at ebp-8
.recent_restsize dd     ?       ; this is for memory alloc in ._.generate_data
.recent_page    dd      ?       ; this is for memory alloc in ._.generate_data
        rd      5       ; saved regs and return address
.hostname       dd      ?
.servname       dd      ?
.hints          dd      ?
.res            dd      ?
.reqdata        dd      ?
end virtual
        xor     edi, edi
        push    edi     ; init .recent_page
        push    edi     ; init .recent_restsize
; 1. Check that parameters are correct and can be handled by this implementation.
; 1a. If 'res' pointer is given, set result to zero.
        mov     eax, [.res]
        test    eax, eax
        jz      @f
        mov     [eax], edi
@@:
; 1b. Only AI_SUPPORTED flags are supported for hints->ai_flags.
        mov     ecx, [.hints]
        xor     edx, edx
        jecxz   .nohints
        mov     edx, [ecx+addrinfo.ai_flags]
.nohints:
        mov     ebx, [.reqdata]
        mov     [ebx+__gai_reqdata.flags], edx
        push    EAI_BADFLAGS
        pop     eax
        test    edx, not AI_SUPPORTED
        jnz     .ret
; 1c. Either hostname or servname must be given. If AI_CANONNAME is set,
; hostname must also be set.
        cmp     [.hostname], edi
        jnz     @f
        test    dl, AI_CANONNAME
        jnz     .ret
        push    EAI_NONAME
        pop     eax
        cmp     [.servname], edi
        jz      .ret
@@:
; 1d. Only IPv4 is supported, so hints->ai_family must be either PF_UNSPEC or PF_INET.
        push    EAI_FAMILY
        pop     eax
        jecxz   @f
        cmp     [ecx+addrinfo.ai_family], edi
        jz      @f
        cmp     [ecx+addrinfo.ai_family], AF_INET4
        jnz     .ret
@@:
; 1e. Valid combinations for ai_socktype/ai_protocol: 0/0 for any or
;       SOCK_STREAM/IPPROTO_TCP, SOCK_DGRAM/IPPROTO_UDP
        xor     edx, edx        ; assume 0=any if no hints
        jecxz   .socket_type_ok
        mov     edx, [ecx+addrinfo.ai_socktype]
        mov     esi, [ecx+addrinfo.ai_protocol]
; 1f. Test for ai_socktype=0 and ai_protocol=0.
        test    edx, edx
        jnz     .check_socktype
        test    esi, esi
        jz      .socket_type_ok
; 1g. ai_socktype=0, ai_protocol is nonzero.
        push    EAI_SERVICE
        pop     eax
        inc     edx     ; edx = SOCK_STREAM
        cmp     esi, IPPROTO_TCP
        jz      .socket_type_ok
        inc     edx     ; edx = SOCK_DGRAM
        cmp     esi, IPPROTO_UDP
        jz      .socket_type_ok
.ret:
; Restore saved registers, destroy stack frame and return.
        mov     esp, ebp
        pop     ebp
        pop     edi esi ebx
        ret     20
; 1h. ai_socktype is nonzero.
.check_socktype:
        push    EAI_SOCKTYPE
        pop     eax
        cmp     edx, SOCK_STREAM
        jz      .check_tcp
        cmp     edx, SOCK_DGRAM
        jnz     .ret
        test    esi, esi
        jz      .socket_type_ok
        cmp     esi, IPPROTO_UDP
        jz      .socket_type_ok
        jmp     .ret
.check_tcp:
        test    esi, esi
        jz      .socket_type_ok
        cmp     esi, IPPROTO_TCP
        jnz     .ret
.socket_type_ok:
        mov     [ebx+__gai_reqdata.socktype], dl
; 2. Resolve service.
; 2a. If no name is given, remember value -1.
        push    -1
        pop     edx
        mov     esi, [.servname]
        test    esi, esi
        jz      .service_resolved
; 2b. Loop for characters of string while digits are encountered.
        xor     edx, edx
        xor     eax, eax
.serv_to_number:
        lodsb
        sub     al, '0'
        cmp     al, 9
        ja      .serv_to_number_done
; for each digit, set edx = edx*10 + <digit>
        lea     edx, [edx*5]
        lea     edx, [edx*2+eax]
; check for correctness: service port must fit in word
        cmp     edx, 0x10000
        jae     .service_not_number
        jmp     .serv_to_number
.serv_to_number_done:
        and     edx, 0xFFFF     ; make sure that port fits
; 2c. If zero character reached, name is resolved;
; otherwise, return error (no support for symbolic names yet)
        cmp     al, -'0'
        jz      .service_resolved
.service_not_number:
        push    EAI_NONAME
        pop     eax
        jmp     .ret
.service_resolved:
; 2d. Save result to reqdata.
        mov     [ebx+__gai_reqdata.service], edx
; 3. Process host name.
        mov     esi, [.hostname]
; 3a. If hostname is not given,
;       use localhost for active sockets and INADDR_ANY for passive sockets.
        mov     eax, 0x0100007F ; 127.0.0.1 in network byte order
        test    byte [ebx+__gai_reqdata.flags], AI_PASSIVE
        jz      @f
        xor     eax, eax
@@:
        test    esi, esi
        jz      .hostname_is_ip
; 3b. Check for dotted IPv4 name.
        push    esi
        call    inet_addr
        cmp     eax, -1
        jz      .resolve_hostname
.hostname_is_ip:
; 3c. hostname is valid representation of IP address, and we have resolved it.
; Generate result, if .res pointer is not NULL.
        mov     ebx, [.reqdata]
        mov     esi, [.res]
        test    esi, esi
        jz      .no_result
        call    getaddrinfo._.generate_data
; 3d. Check for memory allocation error.
.3d:
        push    EAI_MEMORY
        pop     eax
        test    esi, esi
        jz      .ret
; 3e. If AI_CANONNAME is set, copy input name.
        test    byte [ebx+__gai_reqdata.flags], AI_CANONNAME
        jz      .no_result
; 3f. Calculate length of name.
        push    -1
        pop     ecx
        mov     edi, [.hostname]
        xor     eax, eax
        repnz   scasb
        not     ecx
; 3g. Check whether it fits on one page with main data.
        cmp     ecx, [.recent_restsize]
        jbe     .name_fits
; 3h. If not, allocate new page.
        push    ecx
        add     ecx, 4  ; first dword contains number of objects on the page
        mcall   68, 12
        pop     ecx
; 3i. If allocation has failed, free addrinfo and return error.
        test    eax, eax
        jnz     .name_allocated
        push    [.res]
        call    freeaddrinfo
        push    EAI_MEMORY
        pop     eax
        jmp     .ret
.name_allocated:
; 3j. Otherwise, set edi to allocated memory and continue to 3l.
        xchg    edi, eax        ; put result to edi
        push    1
        pop     eax
        stosd   ; number of objects on the page = 1
        jmp     .copy_name
.name_fits:
; 3k. Get pointer to free memory in allocated page.
        mov     edi, [.recent_page]
        mov     eax, edi
        and     eax, not 0xFFF
        inc     dword [eax]     ; increase number of objects
.copy_name:
; 3l. Put pointer to struct addrinfo.
        mov     eax, [.res]
        mov     eax, [eax]
        mov     [eax+addrinfo.ai_canonname], edi
; 3m. Copy name.
        rep     movsb
.no_result:
; 3n. Return success.
        xor     eax, eax
        jmp     .ret
; 4. Host address is not dotted IP. Test whether we are allowed to contact DNS.
; Return error if no.
.resolve_hostname:
        push    EAI_NONAME
        pop     eax
        mov     ebx, [.reqdata]
        test    byte [ebx+__gai_reqdata.flags], AI_NUMERICHOST
        jnz     .ret
; Host address is domain name. Contact DNS server.
        mov     esi, [.hostname]
; 5. Reserve stack place for UDP packet.
; According to RFC1035, maximum UDP packet size in DNS is 512 bytes.
        sub     esp, 512
; 6. Create DNS request packet.
; 6a. Set pointer to start of buffer.
        mov     edi, esp
; 6b. Get request ID, write it to buffer.
        push    1
        pop     eax
lock    xadd    [DNSrequestID], eax     ; atomically increment ID, get old value
        stosw
        mov     [ebx+__gai_reqdata.reqid], ax
; 6c. Packed field: QR=0 (query), Opcode=0000 (standard query),
;       AA=0 (ignored in requests), TC=0 (no truncation),
;       RD=1 (recursion desired)
        mov     al, 00000001b
        stosb
; 6d. Packed field: ignored in requests
        mov     al, 0
        stosb
; 6e. Write questions count = 1 and answers count = 0
; Note that network byte order is big-endian.
        mov     eax, 0x00000100
        stosd
; 6f. Write nameservers count = 0 and additional records count = 0
        xor     eax, eax
        stosd
; 6g. Write request data: name
; According to RFC1035, maximum length of name is 255 bytes.
; For correct names, buffer cannot overflow.
        lea     ebx, [esi+256]  ; ebx = limit for name (including terminating zero)
; translate string "www.yandex.ru" {00} to byte data {03} "www" {06} "yandex" {02} "ru" {00}
.nameloop:      ; here we go in the start of each label: before "www", before "yandex", before "ru"
        xor     ecx, ecx        ; ecx = length of current label
        inc     edi     ; skip length, it will be filled later
.labelloop:     ; here we go for each symbol of name
        lodsb   ; get next character
        test    al, al  ; terminating zero?
        jz      .endname
        cmp     esi, ebx        ; limit exceeded?
        jae     .wrongname
        cmp     al, '.' ; end of label?
        jz      .labelend
        stosb   ; put next character
        inc     ecx     ; increment label length
        jmp     .labelloop
.wrongname:
        push    EAI_NONAME
        pop     eax
        jmp     .ret
.labelend:
        test    ecx, ecx        ; null label can be only in the end of name
        jz      .wrongname
.endname:
        cmp     ecx, 63
        ja      .wrongname
; write length to byte [edi-ecx-1]
        mov     eax, ecx
        neg     eax
        mov     byte [edi+eax-1], cl
        cmp     byte [esi-1], 0 ; that was last label in the name?
        jnz     .nameloop
; write terminating zero if not yet
        mov     al, 0
        cmp     byte [edi-1], al
        jz      @f
        stosb
@@:
; 6h. Write request data:
;       query type = A (host address) = 1,
;       query class = IN (internet IPv4 address) = 1
; Note that network byte order is big-endian.
        mov     eax, 0x01000100
        stosd
; 7. Get DNS server address.
        mcall   76, API_IPv4 + (1 shl 8) + 4 ; protocol IP=0, device number=0, function=get DNS address
        cmp     eax, -1
        je      .ret.dnserr
        push    eax             ; save server address to the stack
; 8. Open UDP socket to DNS server, port 53.
; 8a. Create new socket.
        mcall   75, 0, AF_INET4, SOCK_DGRAM, 0
        pop     esi             ; restore server address saved at step 7
        cmp     eax, -1         ; error?
        jz      .ret.dnserr
        mov     ecx, eax        ; put socket handle to ecx
; 8b. Create sockaddr structure on the stack.
        push    0
        push    0       ; sin_zero
        push    esi     ; sin_addr
        push    AF_INET4 + (53 shl 24)
                        ; sin_family and sin_port in network byte order
; 8c. Connect.
        mcall   75, 4, , esp, sizeof.sockaddr_in
; 8d. Restore the stack, undo 8b.
        add     esp, esi
; 8e. Check result.
        cmp     eax, -1
        jz      .ret.close
; 9. Send DNS request packet.
        sub     edi, esp        ; get packet length
        mov     esi, edi
        xor     edi, edi
        mcall   75, 6, , esp
        cmp     eax, -1
        jz      .ret.close
        mov     eax, [.reqdata]
        mov     [eax+__gai_reqdata.socketnum], ecx
        push    -1
        pop     eax     ; return status: more processing required
        jmp     .ret.dns
.ret.close:
        mcall   75, 1
.ret.dnserr:
        push    EAI_AGAIN
        pop     eax
.ret.dns:
; 6. Restore stack pointer and return.
        jmp     .ret

;;===========================================================================;;
;; int __stdcall getaddrinfo_process(__in struct __gai_reqdata* reqdata,     ;;
;;                                   __out struct addrinfo** res);           ;;
getaddrinfo_process:                                                         ;;
;;---------------------------------------------------------------------------;;
;? Processes network events from DNS reply                                   ;;
;;---------------------------------------------------------------------------;;
;> first parameter = pointer to struct __gai_reqdata filled by ..._start     ;;
;> second parameter = same as for getaddrinfo                                ;;
;;---------------------------------------------------------------------------;;
;< eax = -1 if more processing required / 0 on success / >0 = error code     ;;
;;===========================================================================;;
; 0. Create stack frame.
        push    ebp
        mov     ebp, esp
virtual at ebp-.locals_size
.locals_start:
.datagram       rb      512
.addrname       dd      ?
.name           dd      ?
.res_list_tail  dd      ?
.cname          dd      ?
.recent_restsize dd     ?       ; this is for memory alloc in ._.generate_data
.recent_page    dd      ?       ; this is for memory alloc in ._.generate_data
.locals_size = $ - .locals_start
                rd      2
.reqdata        dd      ?
.res            dd      ?
end virtual
        xor     eax, eax
        push    eax     ; initialize .recent_page
        push    eax     ; initialize .recent_restsize
        push    eax     ; initialize .cname
        push    [.res]  ; initialize .res_list_tail
        sub     esp, .locals_size-16    ; reserve place for other vars
        mov     edx, esp        ; edx -> buffer for datagram
; 1. Save used registers for __stdcall.
        push    ebx esi edi
        mov     edi, [.reqdata]
; 2. Read UDP datagram.
        mov     ecx, [edi+__gai_reqdata.socketnum]
        push    edi
        mcall   75, 7, , , 512, MSG_DONTWAIT
        pop     edi
; 3. Check for socket errors
        cmp     eax, -1
        jne     @f
        cmp     ebx, EWOULDBLOCK
        je      .ret.more_processing_required
        jmp     .ret.no_recovery
  @@:
; 4. Sanity check: discard too short packets.
        xchg    ecx, eax        ; save packet length in ecx
        cmp     ecx, 12
        jb      .ret.more_processing_required
; 5. Discard packets with ID != request ID.
        mov     eax, dword [edi+__gai_reqdata.reqid]
        cmp     ax, [edx]
        jnz     .ret.more_processing_required
; 6. Sanity check: discard query packets.
        test    byte [edx+2], 80h
        jz      .ret.more_processing_required
; 7. Sanity check: must be exactly one query (our).
        cmp     word [edx+4], 0x0100    ; note network byte order
        jnz     .ret.more_processing_required
; 8. Check for errors. Return EAI_NONAME for error code 3 and EAI_FAIL for other.
        mov     al, [edx+3]
        and     al, 0xF
        jz      @f
        cmp     al, 3
        jnz     .ret.no_recovery
        jmp     .ret.no_name
@@:
; 9. Locate answers section. Exactly 1 query is present in this packet.
        add     ecx, edx        ; ecx = limit
        lea     esi, [edx+12]
        call    .skip_name
        lodsd           ; skip QTYPE and QCLASS field
        cmp     esi, ecx
        ja      .ret.no_recovery
; 10. Loop through all answers.
        movzx   ebx, word [edx+6]       ; get answers count
        xchg    bl, bh          ; network -> Intel byte order
.answers_loop:
        dec     ebx
        js      .answers_done
; 10a. Process each record.
        mov     [.name], esi
; 10b. Skip name field.
        call    .skip_name
; 10c. Get record information, handle two types for class IN (internet).
        lodsd           ; get type and class
        cmp     esi, ecx
        ja      .ret.no_recovery
        cmp     eax, 0x01000500 ; type=5, class=1?
        jz      .got_cname
        cmp     eax, 0x01000100 ; type=1, class=1?
        jnz     .answers_loop.next
.got_addr:
; 10d. Process record A, host address.
        add     esi, 10
        cmp     esi, ecx
        ja      .ret.no_recovery
        cmp     word [esi-6], 0x0400    ; RDATA for A records must be 4 bytes long
        jnz     .ret.no_recovery
        mov     eax, [.name]
        mov     [.addrname], eax
; 10e. Create corresponding record in the answer.
        push    ebx ecx esi
        mov     eax, [esi-4]    ; IP address
        mov     esi, [.res_list_tail]   ; pointer to result
        test    esi, esi
        jz      .no_result      ; do not save if .res is NULL
        mov     ebx, [.reqdata] ; request data
        call    getaddrinfo._.generate_data
        mov     [.res_list_tail], esi
        pop     esi ecx ebx
        cmp     [.res_list_tail], 0
        jnz     .answers_loop
; 10f. If generate_data failed (this means memory allocation failure), abort
        jmp     .ret.no_memory
.no_result:
        pop     esi ecx ebx
        jmp     .answers_loop
.got_cname:
; 10g. Process record CNAME, main host name.
        lea     eax, [esi+6]
        mov     [.cname], eax
.answers_loop.next:
; 10h. Skip other record fields, advance to next record.
        lodsd   ; skip TTL
        xor     eax, eax
        lodsw   ; get length of RDATA field
        xchg    al, ah  ; network -> Intel byte order
        add     esi, eax
        cmp     esi, ecx
        ja      .ret.no_recovery
        jmp     .answers_loop
.answers_done:
; 11. Check that there is at least 1 answer.
        mov     eax, [.res_list_tail]
        cmp     [.res], eax
        jz      .ret.no_data
; 12. If canonical name was required, add it now.
        mov     eax, [.reqdata]
        test    byte [eax+__gai_reqdata.flags], AI_CANONNAME
        jz      .no_canon_name
; 12a. If at least one CNAME record is present, use name from last such record.
; Otherwise, use name from one of A records.
        mov     esi, [.cname]
        test    esi, esi
        jnz     .has_cname
        mov     esi, [.addrname]
.has_cname:
; 12b. Calculate name length.
        call    .get_name_length
        jc      .ret.no_recovery
; 12c. Check that the caller really want to get data.
        cmp     [.res], 0
        jz      .no_canon_name
; 12d. Allocate memory for name.
        call    getaddrinfo._.memalloc
        test    edi, edi
        jz      .ret.no_memory
; 12e. Make first entry in .res list point to canonical name.
        mov     eax, [.res]
        mov     eax, [eax]
        mov     [eax+addrinfo.ai_canonname], edi
; 12f. Decode name.
        call    .decode_name
.no_canon_name:
; 13. Set status to success.
        xor     eax, eax
        jmp     .ret.close
; Handle errors.
.ret.more_processing_required:
        push    -1
        pop     eax
        jmp     .ret
.ret.no_recovery:
        push    EAI_FAIL
        pop     eax
        jmp     .ret.destroy
.ret.no_memory:
        push    EAI_MEMORY
        pop     eax
        jmp     .ret.destroy
.ret.no_name:
.ret.no_data:
        push    EAI_NONAME
        pop     eax
.ret.destroy:
; 14. If an error occured, free memory acquired so far.
        push    eax
        mov     esi, [.res]
        test    esi, esi
        jz      @f
        pushd   [esi]
        call    freeaddrinfo
        and     dword [esi], 0
@@:
        pop     eax
.ret.close:
; 15. Close socket.
        push    eax
        mov     ecx, [.reqdata]
        mov     ecx, [ecx+__gai_reqdata.socketnum]
        mcall   75, 1
        pop     eax
; 16. Restore used registers, destroy stack frame and return.
.ret:
        pop     edi esi ebx
        mov     esp, ebp
        pop     ebp
        ret     8

;;===========================================================================;;
;; Internal auxiliary function for skipping names in DNS packet.             ;;
.skip_name:                                                                  ;;
;;---------------------------------------------------------------------------;;
;? Skips name in DNS packet.                                                 ;;
;;---------------------------------------------------------------------------;;
;> esi -> name                                                               ;;
;> ecx = end of packet                                                       ;;
;;---------------------------------------------------------------------------;;
;< esi -> end of name                                                        ;;
;;===========================================================================;;
        xor     eax, eax
        cmp     esi, ecx
        jae     .skip_name.done
        lodsb
        test    al, al
        jz      .skip_name.done
        test    al, 0xC0
        jnz     .skip_name.pointer
        add     esi, eax
        jmp     .skip_name
.skip_name.pointer:
        inc     esi
.skip_name.done:
        ret

;;===========================================================================;;
;; Internal auxiliary function for calculating length of name in DNS packet. ;;
.get_name_length:                                                            ;;
;;---------------------------------------------------------------------------;;
;? Calculate length of name (including terminating zero) in DNS packet.      ;;
;;---------------------------------------------------------------------------;;
;> edx = start of packet                                                     ;;
;> esi -> name                                                               ;;
;> ecx = end of packet                                                       ;;
;;---------------------------------------------------------------------------;;
;< eax = length of name                                                      ;;
;< CF set on error / cleared on success                                      ;;
;;===========================================================================;;
        xor     ebx, ebx        ; ebx will hold data length
.get_name_length.zero:
        xor     eax, eax
.get_name_length.loop:
        cmp     esi, ecx
        jae     .get_name_length.fail
        lodsb
        test    al, al
        jz      .get_name_length.done
        test    al, 0xC0
        jnz     .get_name_length.pointer
        add     esi, eax
        inc     ebx
        add     ebx, eax
        cmp     ebx, 256
        jbe     .get_name_length.loop
.get_name_length.fail:
        stc
        ret
.get_name_length.pointer:
        and     al, 0x3F
        mov     ah, al
        lodsb
        lea     esi, [edx+eax]
        jmp     .get_name_length.zero
.get_name_length.done:
        test    ebx, ebx
        jz      .get_name_length.fail
        xchg    eax, ebx
        clc
        ret

;;===========================================================================;;
;; Internal auxiliary function for decoding DNS name.                        ;;
.decode_name:                                                                ;;
;;---------------------------------------------------------------------------;;
;? Decode name in DNS packet.                                                ;;
;;---------------------------------------------------------------------------;;
;> edx = start of packet                                                     ;;
;> esi -> name in packet                                                     ;;
;> edi -> buffer for decoded name                                            ;;
;;===========================================================================;;
        xor     eax, eax
        lodsb
        test    al, al
        jz      .decode_name.done
        test    al, 0xC0
        jnz     .decode_name.pointer
        mov     ecx, eax
        rep     movsb
        mov     al, '.'
        stosb
        jmp     .decode_name
.decode_name.pointer:
        and     al, 0x3F
        mov     ah, al
        lodsb
        lea     esi, [edx+eax]
        jmp     .decode_name
.decode_name.done:
        mov     byte [edi-1], 0
        ret

;;===========================================================================;;
;; Internal auxiliary function for allocating memory for getaddrinfo.        ;;
getaddrinfo._.memalloc:                                                      ;;
;;---------------------------------------------------------------------------;;
;? Memory allocation.                                                        ;;
;;---------------------------------------------------------------------------;;
;> eax = size in bytes, must be less than page size.                         ;;
;> [ebp-4] = .recent_page = last allocated page                              ;;
;> [ebp-8] = .recent_restsize = bytes rest in last allocated page            ;;
;;---------------------------------------------------------------------------;;
;< edi -> allocated memory / NULL on error                                   ;;
;;===========================================================================;;
; 1. Set edi to result of function.
        mov     edi, [ebp-4]
; 2. Check whether we need to allocate a new page.
        cmp     eax, [ebp-8]
        jbe     .no_new_page
; 2. Allocate new page if need. Reset edi to new result.
        push    eax ebx
        mcall   68, 12, 0x1000
        xchg    edi, eax        ; put result to edi
        pop     ebx eax
; 3. Check returned value of allocator. Fail if it failed.
        test    edi, edi
        jz      .ret
; 4. Update .recent_page and .recent_restsize.
        add     edi, 4
        sub     ecx, 4
        mov     [ebp-4], edi
        mov     [ebp-8], ecx
.no_new_page:
; 5. Increase number of objects on this page.
        push    eax
        mov     eax, edi
        and     eax, not 0xFFF
        inc     dword [eax]
        pop     eax
; 6. Advance last allocated pointer, decrease memory size.
        add     [ebp-4], eax
        sub     [ebp-8], eax
; 7. Return.
.ret:
        ret

;;===========================================================================;;
;; Internal auxiliary function for freeing memory for freeaddrinfo.          ;;
getaddrinfo._.memfree:                                                       ;;
;;---------------------------------------------------------------------------;;
;? Free memory.                                                              ;;
;;---------------------------------------------------------------------------;;
;> eax = pointer                                                             ;;
;;===========================================================================;;
; 1. Get start of page.
        mov     ecx, eax
        and     ecx, not 0xFFF
; 2. Decrease number of objects.
        dec     dword [ecx]
; 3. If it goes to zero, free the page.
        jnz     @f
        push    ebx
        mcall   68, 13
        pop     ebx
@@:
; 4. Done.
        ret

;;===========================================================================;;
getaddrinfo._.generate_data:                                                 ;;
;;---------------------------------------------------------------------------;;
;? Generate item(s) of getaddrinfo result list by one IP address.            ;;
;;---------------------------------------------------------------------------;;
;> eax = IP address                                                          ;;
;> ebx = request data                                                        ;;
;> esi = pointer to result                                                   ;;
;> [ebp-4] = .recent_page = last allocated page                              ;;
;> [ebp-8] = .recent_restsize = bytes rest in last allocated page            ;;
;;---------------------------------------------------------------------------;;
;< esi = pointer to next list item for result / NULL on error                ;;
;;===========================================================================;;
; 1. If no service is given, append one item with zero port.
; append one item with zero socktype/protocol/port.
        cmp     [ebx+__gai_reqdata.service], -1
        jnz     .has_service
        call    .append_item
; 1a. If neither protocol nor socktype were specified,
;       leave zeroes in socktype and protocol.
        mov     cl, [ebx+__gai_reqdata.socktype]
        test    cl, cl
        jz      .no_socktype
; 1b. Otherwise, set socktype and protocol to desired.
        call    .set_socktype
.no_socktype:
        ret
.has_service:
; 2. If TCP is allowed, append item for TCP.
        cmp     [ebx+__gai_reqdata.socktype], 0
        jz      .tcp_ok
        cmp     [ebx+__gai_reqdata.socktype], SOCK_STREAM
        jnz     .tcp_disallowed
.tcp_ok:
        call    .append_item
        mov     cl, SOCK_STREAM
        call    .set_socktype
        call    .set_port
.tcp_disallowed:
; 3. If UDP is allowed, append item for UDP.
        cmp     [ebx+__gai_reqdata.socktype], 0
        jz      .udp_ok
        cmp     [ebx+__gai_reqdata.socktype], SOCK_DGRAM
        jnz     .udp_disallowed
.udp_ok:
        call    .append_item
        mov     cl, SOCK_DGRAM
        call    .set_socktype
        call    .set_port
.udp_disallowed:
        ret

.append_item:
; 1. Allocate memory for struct sockaddr_in and struct addrinfo.
        push    eax
        push    sizeof.addrinfo + sizeof.sockaddr_in
        pop     eax
        call    getaddrinfo._.memalloc
; 2. Check for memory allocation fail.
        test    edi, edi
        jz      .no_memory
; 3. Zero allocated memory.
        push    (sizeof.addrinfo + sizeof.sockaddr_in) / 4
        pop     ecx
        xor     eax, eax
        push    edi
        rep     stosd
        pop     edi
; 4. Fill struct addrinfo.
        mov     eax, [ebx+__gai_reqdata.flags]
        mov     [edi+addrinfo.ai_flags], eax
        mov     byte [edi+addrinfo.ai_family], AF_INET4
        mov     byte [edi+addrinfo.ai_addrlen], sizeof.sockaddr_in
        lea     ecx, [edi+sizeof.addrinfo]
        mov     [edi+addrinfo.ai_addr], ecx
; 5. Fill struct sockaddr_in.
        mov     byte [ecx+sockaddr_in.sin_family], AF_INET4
        pop     eax
        mov     [ecx+sockaddr_in.sin_addr], eax
; 6. Append new item to the list.
        mov     [esi], edi
        lea     esi, [edi+addrinfo.ai_next]
; 7. Return.
        ret
.no_memory:
        pop     eax
        xor     esi, esi
        ret

.set_socktype:
; Set ai_socktype and ai_protocol fields by given socket type.
        mov     byte [edi+addrinfo.ai_socktype], cl
        dec     cl
        jnz     .set_udp
.set_tcp:
        mov     byte [edi+addrinfo.ai_protocol], IPPROTO_TCP
        ret
.set_udp:
        mov     byte [edi+addrinfo.ai_protocol], IPPROTO_UDP
        ret

.set_port:
; Just copy port from input __gai_reqdata to output addrinfo.
        push    edx
        mov     edx, [ebx+__gai_reqdata.service]
        xchg    dl, dh  ; convert to network byte order     ;;;;; CHECKME
        mov     [edi+sizeof.addrinfo+sockaddr_in.sin_port], dx
        pop     edx
        ret

;;===========================================================================;;
;; void __stdcall getaddrinfo_abort(__in struct __gai_reqdata* reqdata);      ;;
getaddrinfo_abort:                                                           ;;
;;---------------------------------------------------------------------------;;
;? Abort process started by getaddrinfo_start, free all resources.           ;;
;;---------------------------------------------------------------------------;;
;> first parameter = pointer to struct __gai_reqdata filled by ..._start     ;;
;;===========================================================================;;
; 0. Save used registers for __stdcall.
        push    ebx
; 1. Allocated resources: only socketnum, so close it and return.
        mov     eax, [esp+8]
        mov     ecx, [eax+__gai_reqdata.socketnum]
        mcall   75, 1
; 2. Restore used registers and return.
        pop     ebx
        ret     4

;;===========================================================================;;
;; void __stdcall freeaddrinfo(__in struct addrinfo* ai);                    ;;
freeaddrinfo:                                                                ;;
;;---------------------------------------------------------------------------;;
;? Free one or more addrinfo structures returned by getaddrinfo.             ;;
;;---------------------------------------------------------------------------;;
;> first parameter = head of list of structures                              ;;
;                    (may be arbitrary sublist of original)                  ;;
;;===========================================================================;;
; 1. Loop for all items in the list.
        mov     edx, [esp+4]    ; eax = ai
.loop:
        test    edx, edx
        jz      .done
; 2. Free each item.
; 2a. Free ai_canonname, if allocated.
        mov     eax, [edx+addrinfo.ai_canonname]
        test    eax, eax
        jz      .no_canon_name
        call    getaddrinfo._.memfree
.no_canon_name:
; 2b. Remember next item
;       (after freeing the field ai_next can became unavailable).
        pushd   [edx+addrinfo.ai_next]
; 2c. Free item itself.
        xchg    eax, edx
        call    getaddrinfo._.memfree
; 2d. Restore pointer to next item and continue loop.
        pop     edx
        jmp     .loop
.done:
; 3. Done.
        ret     4

;;===========================================================================;;
;;///////////////////////////////////////////////////////////////////////////;;
;;===========================================================================;;
;! Exported functions section                                                ;;
;;===========================================================================;;
;;///////////////////////////////////////////////////////////////////////////;;
;;===========================================================================;;


align 4
@EXPORT:
export  \
        lib_init                , 'lib_init'            , \
        0x00010001              , 'version'             , \
        inet_addr               , 'inet_addr'           , \
        inet_ntoa               , 'inet_ntoa'           , \
        getaddrinfo             , 'getaddrinfo'         , \
        getaddrinfo_start       , 'getaddrinfo_start'   , \
        getaddrinfo_process     , 'getaddrinfo_process' , \
        getaddrinfo_abort       , 'getaddrinfo_abort'   , \
        freeaddrinfo            , 'freeaddrinfo'

section '.data' data readable writable align 16
; uninitialized data
mem.alloc   dd ?
mem.free    dd ?
mem.realloc dd ?
dll.load    dd ?

DNSrequestID    dd      ?

inet_ntoa.buffer        rb      16      ; static buffer for inet_ntoa