modules/pxechain.asm

   1 ; "$Id: pxechain.asm,v 1.2 2007/12/16 08:15:39 jhutz Exp $"
   2 ; -*- fundamental -*- (asm-mode sucks)  vim:noet:com=\:;
   3 ; ****************************************************************************
   4 ;
   5 ;  pxechain.asm
   6 ;
   7 ;  A comboot program to chain from PXELINUX to another PXE network
   8 ;  bootstrap program (NBP).  This improves on PXELINUX's built-in PXE
   9 ;  chaining support by arranging for the server address and boot filename
  10 ;  reported by the PXE stack to be those from which the new NBP was
  11 ;  loaded, allowing PXELINUX to be used to select from multiple NBP's,
  12 ;  such as gPXE, another PXELINUX(*), Windows RIS, and so on.
  13 ;
  14 ;  (*) This seems unnecessary at first, but it is very helpful when
  15 ;  selecting from among self-contained network boot images.
  16 ;
  17 ;   Copyright (c) 2007 Carnegie Mellon University
  18 ;   Copyright (C) 1994-2007  H. Peter Anvin
  19 ;
  20 ;  This program is free software; you can redistribute it and/or modify
  21 ;  it under the terms of the GNU General Public License as published by
  22 ;  the Free Software Foundation, Inc., 53 Temple Place Ste 330,
  23 ;  Boston MA 02111-1307, USA; either version 2 of the License, or
  24 ;  (at your option) any later version; incorporated herein by reference.
  25 ;
  26 ; ****************************************************************************
  27
  28 ;%define DEBUG
  29 ;%define NO_RUN
  30
  31                 absolute 0
  32 pspInt20:       resw 1
  33 pspNextP:       resw 1
  34                 resb 124
  35 pspCmdLen:      resb 1
  36 pspCmdArg:      resb 127
  37
  38                 section .text
  39                 org     0x100
  40
  41 %ifdef DEBUG
  42 %macro MARK 1.nolist
  43                 mov ah,0x02
  44                 mov dl,%1&0xff
  45                 int 0x21
  46 %if (%1 >> 8) & 0xff
  47                 mov dl,(%1 >> 8) & 0xff
  48                 int 0x21
  49 %if (%1 >> 16) & 0xff
  50                 mov dl,(%1 >> 16) & 0xff
  51                 int 0x21
  52 %if (%1 >> 24) & 0xff
  53                 mov dl,(%1 >> 24) & 0xff
  54                 int 0x21
  55 %endif
  56 %endif
  57 %endif
  58                 mov dl,' '
  59                 int 0x21
  60 %endmacro
  61 %macro SHOWD 1.nolist
  62                 mov al,%1
  63                 call print_dec
  64                 mov ah,0x02
  65                 mov dl,' '
  66                 int 0x21
  67 %endmacro
  68 %macro SHOWX 1.nolist
  69                 mov bx,%1
  70                 call print_hex
  71                 mov ah,0x02
  72                 mov dl,' '
  73                 int 0x21
  74 %endmacro
  75 %else
  76 %macro MARK 1.nolist
  77 %endmacro
  78 %macro SHOWD 1.nolist
  79 %endmacro
  80 %macro SHOWX 1.nolist
  81 %endmacro
  82 %endif
  83
  84 _start:
  85                 MARK 'INIT'
  86
  87 ; There should be exactly one command-line argument, which is of the form
  88 ; [[ipaddress]::]tftp_filename, just like filenames given to PXELINUX.
  89 ; Too few or too many arguments is an error.
  90 ;
  91 ; This code is based on mangle_name in pxelinux.asm
  92 parse_args:
  93                 cld
  94                 xor cx,cx
  95                 mov cl,[pspCmdLen]
  96                 dec cx
  97                 mov si,pspCmdArg+1
  98                 and cx,cx
  99                 je near usage           ; no args is bad
 100                 add si,cx
 101                 dec si
 102                 std
 103 .chomp:         lodsb
 104                 cmp al,' '
 105                 loopz .chomp
 106                 inc cx
 107                 cld
 108                 mov [pspCmdLen],cl
 109                 mov si,pspCmdArg+1
 110                 cmp word [si],'::'      ; Leading ::?
 111                 je near gotprefix
 112                 dec cx
 113                 jz noip
 114                 MARK 'SCAN'
 115
 116 .more:
 117                 inc si
 118                 cmp byte [si],' '
 119                 je near usage
 120                 cmp word [si],'::'
 121                 je near parse_ip
 122                 loop .more
 123
 124 noip:
 125                 MARK 'NOIP'
 126                 mov ax,0x0e             ; get config file name
 127                 int 0x22
 128                 mov si,bx
 129 %ifdef DEBUG
 130                 mov ah,0x02
 131                 mov dl,'['
 132                 int 0x21
 133                 mov ax,0x02
 134                 int 0x22
 135                 mov ah,0x02
 136                 mov dl,']'
 137                 int 0x21
 138                 mov dl,' '
 139                 int 0x21
 140 %endif
 141                 push ds
 142                 push es
 143                 pop ds
 144                 pop es
 145                 push es
 146 .find_prefix:
 147                 lodsb
 148                 and al,al
 149                 jnz .find_prefix
 150                 dec si
 151
 152                 mov cx,si
 153                 sub cx,bx
 154                 MARK 'LEN'
 155                 SHOWD cl                ; assume it's <256 for debugging
 156                 dec si
 157                 std
 158 .find_slash:
 159                 lodsb
 160                 cmp al,'/'
 161                 je .slash
 162                 loop .find_slash
 163 .slash:
 164                 cmp cx,127
 165                 cld
 166                 jna .copy_prefix
 167                 pop ds
 168                 jmp too_long
 169
 170 .copy_prefix:
 171                 SHOWD cl
 172                 MARK 'PFX'
 173                 mov si,bx
 174                 mov di,tftp_filename
 175                 mov bx,128
 176                 sub bx,cx
 177                 rep movsb
 178                 pop ds
 179
 180                 mov cl,[pspCmdLen]
 181                 mov si,pspCmdArg+1
 182                 jmp prefix_done
 183
 184 usage:
 185                 xor cx,cx
 186                 mov si,msg_usage
 187                 jmp fail
 188
 189 too_long:
 190                 xor cx,cx
 191                 mov si,msg_too_long
 192                 jmp fail
 193
 194 parse_ip:
 195                 MARK 'PIP'
 196                 mov di,si
 197                 mov si,pspCmdArg+1
 198                 call parse_dotquad
 199                 jc .notdq
 200                 cmp si,di               ; is it the same place?
 201                 jne .notdq
 202                 mov [tftp_siaddr],eax
 203                 jmp gotprefix
 204 .notdq:
 205                 MARK 'NDQ'
 206                 mov si,di
 207                 mov bx,pspCmdArg+1
 208                 mov ax,0x0010           ; DNS resolve
 209                 int 0x22
 210                 and eax,eax
 211                 jz noip
 212                 mov [tftp_siaddr],eax
 213 gotprefix:
 214                 MARK 'GOTP'
 215                 dec cx                  ; skip the ::
 216                 dec cx
 217                 inc si
 218                 inc si
 219                 mov di,tftp_filename
 220                 mov bx,128
 221
 222 prefix_done:
 223                 SHOWD bl
 224                 MARK 'LEFT'
 225
 226 ; SI points at the filename, plus remaining arguments,
 227 ; CX contains their combined length.
 228 ; DI points to where the filename should be stored
 229 ; BX says how much space is left for the filename and NUL
 230
 231                 and cx,cx
 232                 jz usage                ; no args is bad
 233 .copy_filename:
 234                 lodsb
 235 %ifdef DEBUG
 236                 mov dl,al
 237                 mov ah,0x2
 238                 int 0x21
 239 %endif
 240                 cmp al,' '
 241                 je usage
 242                 dec bx
 243                 jz too_long
 244                 stosb
 245                 loop .copy_filename
 246                 xor eax,eax
 247                 stosb
 248
 249 ; get PXE cached data
 250                 MARK 'GCI'
 251                 mov ax,0x0009           ; call PXE stack
 252                 mov bx,0x0071           ; PXENV_GET_CACHED_INFO
 253                 mov di,PXECacheParms
 254                 int 0x22
 255                 and eax,eax
 256                 jz .fix_siaddr
 257                 mov cx,[gci_status]
 258                 mov si,msg_get_cache
 259                 jmp fail
 260
 261 .fix_siaddr:
 262                 mov bx,[gci_bufferseg]
 263                 mov es,bx
 264                 mov bx,[gci_buffer]
 265                 mov eax,[es:bx+12]      ; save our address (ciaddr)
 266                 mov [open_ciaddr],eax   ; ... in case we have to do UDP open
 267                 mov eax,[tftp_siaddr]
 268                 and eax,eax
 269                 jnz .replace_addr
 270                 MARK 'ADDR'
 271                 mov eax,[es:bx+20]      ; siaddr
 272                 mov [tftp_siaddr],eax
 273                 jmp .addr_done
 274 .replace_addr:
 275                 mov [es:bx+20],eax
 276 .addr_done:
 277                 mov si,tftp_filename    ; copy the new filename...
 278                 lea di,[es:bx+108]      ; to the "cached DHCP response"
 279                 mov cx,128
 280                 rep movsb
 281                 mov bx,ds               ; restore es before proceeding
 282                 mov es,bx
 283
 284 ; print out what we are doing
 285 %ifdef DEBUG
 286                 mov ah,0x02             ; write character
 287                 mov dl,0x0d             ; print a CRLF first
 288                 int 0x21
 289                 mov dl,0x0a
 290                 int 0x21
 291 %endif
 292                 mov ax,0x0002           ; write string
 293                 mov bx,msg_booting
 294                 int 0x22
 295                 mov ebx,[tftp_siaddr]
 296                 call print_dotquad
 297                 mov ah,0x02             ; write character
 298                 mov dl,' '
 299                 int 0x21
 300                 mov ax,0x0002           ; write string
 301                 mov bx,tftp_filename
 302                 int 0x22
 303                 mov ah,0x02             ; write character
 304                 mov dl,0x0d
 305                 int 0x21
 306                 mov dl,0x0a
 307                 int 0x21
 308
 309 %ifndef NO_RUN
 310                 mov ax,0x0009           ; call PXE stack
 311                 mov bx,0x0031           ; PXENV_UDP_CLOSE
 312                 mov di,PXECloseParms
 313                 int 0x22
 314                 mov cx,[close_status]
 315                 mov si,msg_udp_close
 316                 and ax,ax
 317                 jnz fail
 318
 319                 mov ax,0x0009           ; call PXE stack
 320                 mov bx,0x0073           ; PXENV_RESTART_TFTP
 321                 mov di,PXERestartTFTPParms
 322                 int 0x22
 323                 mov cx,[tftp_status]
 324                 mov si,msg_rst_tftp
 325                 call fail
 326
 327                 mov ax,0x0009           ; call PXE stack
 328                 mov bx,0x0030           ; PXENV_UDP_OPEN
 329                 mov di,PXEOpenParms
 330                 int 0x22
 331                 mov cx,[open_status]
 332                 mov si,msg_udp_open
 333                 and ax,ax
 334                 jnz fail
 335                 ret
 336 %endif
 337
 338 fail:
 339                 MARK 'FAIL'
 340                 SHOWX cs
 341                 SHOWX ds
 342                 SHOWX es
 343                 SHOWX si
 344 %ifdef DEBUG
 345                 mov ah,0x02             ; write character
 346                 mov dl,0x0d             ; print a CRLF first
 347                 int 0x21
 348                 mov dl,0x0a
 349                 int 0x21
 350 %endif
 351                 mov ax,0x0002           ; write string
 352                 mov bx,msg_progname     ; print our name
 353                 int 0x22
 354                 mov bx,si               ; ... the error message
 355                 int 0x22
 356                 mov ah,0x02             ; write character
 357                 jcxz .done
 358                 mov dl,' '              ; ... and the error code, in []
 359                 int 0x21
 360                 mov dl,'['
 361                 int 0x21
 362                 mov bx,cx
 363                 call print_hex
 364                 mov ah,0x02             ; write character
 365                 mov dl,']'
 366                 int 0x21
 367 .done:
 368                 mov dl,0x0d             ; and finally a CRLF
 369                 int 0x21
 370                 mov dl,0x0a
 371                 int 0x21
 372                 ret
 373
 374
 375 ; print_hex
 376 ;
 377 ; Take a 16-bit integer in BX and print it as 2 hex digits.
 378 ; Destroys AX and DL.
 379 ;
 380 print_hex:
 381                 mov al,bh
 382                 aam 16
 383                 cmp ah,10
 384                 jb .lt_a000
 385                 add ah,'A'-'0'-10
 386 .lt_a000:       add ah,'0'
 387                 mov dl,ah
 388                 mov ah,0x02             ; write character
 389                 int 0x21
 390
 391                 cmp al,10
 392                 jb .lt_a00
 393                 add al,'A'-'0'-10
 394 .lt_a00:        add al,'0'
 395                 mov dl,al
 396                 mov ah,0x02             ; write character
 397                 int 0x21
 398
 399                 mov al,bl
 400                 aam 16
 401                 cmp ah,10
 402                 jb .lt_a0
 403                 add ah,'A'-'0'-10
 404 .lt_a0:         add ah,'0'
 405                 mov dl,ah
 406                 mov ah,0x02             ; write character
 407                 int 0x21
 408
 409                 cmp al,10
 410                 jb .lt_a
 411                 add al,'A'-'0'-10
 412 .lt_a:          add al,'0'
 413                 mov dl,al
 414                 mov ah,0x02             ; write character
 415                 int 0x21
 416                 ret
 417
 418
 419 ; print_dec
 420 ;
 421 ; Take an 8-bit integer in AL and print it in decimal.
 422 ; Destroys AX and DL.
 423 ;
 424 print_dec:
 425                 cmp al,10               ; < 10?
 426                 jb .lt10                ; If so, skip first 2 digits
 427
 428                 cmp al,100              ; < 100
 429                 jb .lt100               ; If so, skip first digit
 430
 431                 aam 100
 432                 ; Now AH = 100-digit; AL = remainder
 433                 add ah,'0'
 434                 mov dl,ah
 435                 mov ah,0x02
 436                 int 0x21
 437
 438 .lt100:
 439                 aam 10
 440                 ; Now AH = 10-digit; AL = remainder
 441                 add ah,'0'
 442                 mov dl,ah
 443                 mov ah,0x02
 444                 int 0x21
 445
 446 .lt10:
 447                 add al,'0'
 448                 mov dl,al
 449                 mov ah,0x02
 450                 int 0x21
 451                 ret
 452
 453
 454 ; print_dotquad
 455 ;
 456 ; Take an IP address (in network byte order) in EBX and print it
 457 ; as a dotted quad.
 458 ; Destroys EAX, EBX, ECX, EDX
 459 ;
 460 print_dotquad:
 461                 mov cx,3
 462 .octet:
 463                 mov al,bl
 464                 call print_dec
 465                 jcxz .done
 466                 mov ah,0x02
 467                 mov dl,'.'
 468                 int 0x21
 469                 ror ebx,8       ; Move next char into LSB
 470                 dec cx
 471                 jmp .octet
 472 .done:
 473                 ret
 474
 475
 476 ; parse_dotquad:
 477 ;               Read a dot-quad pathname in DS:SI and output an IP
 478 ;               address in EAX, with SI pointing to the first
 479 ;               nonmatching character.
 480 ;
 481 ;               Return CF=1 on error.
 482 ;
 483 ;               No segment assumptions permitted.
 484 ;
 485 parse_dotquad:
 486                 push cx
 487                 mov cx,4
 488                 xor eax,eax
 489 .parseloop:
 490                 mov ch,ah
 491                 mov ah,al
 492                 lodsb
 493                 sub al,'0'
 494                 jb .notnumeric
 495                 cmp al,9
 496                 ja .notnumeric
 497                 aad                             ; AL += 10 * AH; AH = 0;
 498                 xchg ah,ch
 499                 jmp .parseloop
 500 .notnumeric:
 501                 cmp al,'.'-'0'
 502                 pushf
 503                 mov al,ah
 504                 mov ah,ch
 505                 xor ch,ch
 506                 ror eax,8
 507                 popf
 508                 jne .error
 509                 loop .parseloop
 510                 jmp .done
 511 .error:
 512                 loop .realerror                 ; If CX := 1 then we're done
 513                 clc
 514                 jmp .done
 515 .realerror:
 516                 stc
 517 .done:
 518                 dec si                          ; CF unchanged!
 519                 pop cx
 520                 ret
 521
 522                 section .data
 523 msg_booting:    db 'TFTP boot: ',0
 524 msg_progname:   db 'pxechain: ',0
 525 msg_usage:      db 'usage: pxechain.cbt [[ipaddress]::]filename',0dh,0ah,0
 526 msg_too_long:   db 'pxechain: filename is too long (max 127)',0dh,0ah,0
 527 msg_get_cache:  db 'PXENV_GET_CACHED_INFO',0
 528 msg_rst_tftp:   db 'PXENV_RESTART_TFTP',0
 529 msg_udp_close:  db 'PXENV_UDP_CLOSE',0
 530 msg_udp_open:   db 'PXENV_UDP_OPEN',0
 531
 532 PXECacheParms:
 533 gci_status:     dw 0
 534 gci_packettype: dw 3                    ; PXENV_PACKET_TYPE_CACHED_REPLY
 535 gci_buffersize: dw 0
 536 gci_buffer:     dw 0
 537 gci_bufferseg:  dw 0
 538 gci_bufferlim:  dw 0
 539
 540 PXERestartTFTPParms:
 541 tftp_status:    dw 0
 542 tftp_filename:  times 128 db 0
 543 tftp_bufsize:   dd 0x00090000           ; available memory for NBP
 544 tftp_bufaddr:   dd 0x00007c00           ; PXE NBP load address
 545 tftp_siaddr:    dd 0
 546 tftp_giaddr:    dd 0
 547 tftp_mcaddr:    dd 0
 548 tftp_mcport:    dw 0
 549 tftp_msport:    dw 0
 550 tftp_timeout:   dw 0
 551 tftp_reopendly: dw 0
 552
 553 PXECloseParms:
 554 close_status:   dw 0
 555
 556 PXEOpenParms:
 557 open_status:    dw 0
 558 open_ciaddr:    dd 0
 559
 560                 section .bss
 561 ipaddrbuf:      resb 16