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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

;       (raw socketnums are not yet supported by the kernel)

        xor     edx, edx        ; assume 0=any if no hints

        jecxz   .socketnum_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      .socketnum_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      .socketnum_type_ok

        inc     edx     ; edx = SOCK_DGRAM

        cmp     esi, IPPROTO_UDP

        jz      .socketnum_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      .socketnum_type_ok

        cmp     esi, IPPROTO_UDP

        jz      .socketnum_type_ok

        jmp     .ret

.check_tcp:

        test    esi, esi

        jz      .socketnum_type_ok

        cmp     esi, IPPROTO_TCP

        jnz     .ret

.socketnum_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 + 

        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 socketnums and INADDR_ANY for passive socketnums.

        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 socketnum to DNS server, port 53.

; 8a. Create new socketnum.

        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 socketnum 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 socketnum.

        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