Clean up the allocation of local socket numbers. We can now genuinely

guarantee that we don't try to use the same socket number twice.

diff --git a/NEWS b/NEWS
index f419bae..9c0e90d 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -13,6 +13,7 @@ Changes in 1.54:
        * When specifying a "default" command line, no longer
          automatically appent "auto".  See the "DEFAULT" command in
          syslinux.doc for more information.
+       * PXELINUX: Clean up the allocation of local socket numbers.
 
 Changes in 1.53:
        * PXELINUX: Rename pxelinux.bin to pxelinux.0, to match what

diff --git a/pxelinux.asm b/pxelinux.asm
index 726af0b..70014e1 100644 (file)
--- a/pxelinux.asm
+++ b/pxelinux.asm
@@ -22,7 +22,7 @@
 %include "pxe.inc"
 
 ;
-; Macros for byte order
+; Macros for byte order of constants
 ;
 %define htons(x)  ( ( ((x) & 0FFh) << 8 ) + ( ((x) & 0FF00h) >> 8 ) )
 %define ntohs(x) htons(x)
@@ -34,19 +34,20 @@
 ; by the kernel.
 ;
 max_cmd_len    equ 255                 ; Must be odd; 255 is the kernel limit
-FILENAME_MAX   equ 32                  ; Including final null; should be a power of 2
-LOG_FILENAME_MAX equ 5                 ; log2(FILENAME_MAX)
+FILENAME_MAX_LG2 equ 5                 ; log2(Max filename size Including final null)
+FILENAME_MAX   equ (1 << FILENAME_MAX_LG2)
 REBOOT_TIME    equ 5*60                ; If failure, time until full reset
 HIGHMEM_MAX    equ 038000000h          ; Highest address for an initrd
 HIGHMEM_SLOP   equ 128*1024            ; Avoid this much memory near the top
 DEFAULT_BAUD   equ 9600                ; Default baud rate for serial port
 BAUD_DIVISOR   equ 115200              ; Serial port parameter
-MAX_SOCKETS    equ 64                  ; Max number of open sockets
+MAX_SOCKETS_LG2        equ 6                   ; log2(Max number of open sockets)
+MAX_SOCKETS    equ (1 << MAX_SOCKETS_LG2)
 TFTP_PORT      equ htons(69)           ; Default TFTP port 
 PKT_RETRY      equ 6                   ; Packet transmit retry count
 PKT_TIMEOUT    equ 8                   ; Initial timeout, timer ticks @ 55 ms
-TFTP_BLOCKSIZE equ 512                 ; Bytes/block
-LOG_TFTP_BLOCKSIZE equ 9               ; log2(TFTP_BLOCKSIZE)
+TFTP_BLOCKSIZE_LG2 equ 9               ; log2(bytes/block)
+TFTP_BLOCKSIZE equ (1 << TFTP_BLOCKSIZE_LG2)
 
 ;
 ; TFTP operation codes
@@ -999,7 +1000,7 @@ pc_fkey1:  xor cx,cx
                call getline                    ; Get filename to display
                pop si
                pop di
-               shl di,LOG_FILENAME_MAX         ; Convert to offset
+               shl di,FILENAME_MAX_LG2         ; Convert to offset
                add di,FKeyName
                call mangle_name                ; Mangle file name
                jmp short parse_config_3
@@ -1189,7 +1190,7 @@ func_key:
                shr ax,8
 show_help:     ; AX = func key # (0 = F1, 9 = F10)
                mov cl,al
-               shl ax,LOG_FILENAME_MAX         ; Convert to offset
+               shl ax,FILENAME_MAX_LG2         ; Convert to offset
                mov bx,1
                shl bx,cl
                and bx,[FKeyMap]
@@ -2880,12 +2881,27 @@ allocate_socket:
                xor cx,cx                       ; ZF = 1
                pop cx
                ret
-.found:                mov cx,[MySocket]
-               inc cx
-               and cx,0BFFFh                   ; Wrap 32768->49151 (ZF = 0)
-               mov [MySocket],cx
+               ; Allocate a socket number.  Socket numbers are made
+               ; guaranteed unique by including the socket slot number
+               ; (inverted, because we use the loop counter cx); add a
+               ; counter value to keep the numbers from being likely to
+               ; get immediately reused.
+               ;
+               ; The NextSocket variable also contains the top two bits
+               ; set.  This generates a value in the range 49152 to
+               ; 57343.
+.found:
+               dec cx
+               push ax
+               mov ax,[NextSocket]
+               inc ax
+               and ax,((1 << (13-MAX_SOCKETS_LG2))-1) | 0xC000
+               mov [NextSocket],ax
+               shl cx,13-MAX_SOCKETS_LG2
+               add cx,ax                       ; ZF = 0
                xchg ch,cl                      ; Convert to network byte order
                mov [bx],cx                     ; Socket in use
+               pop ax
                pop cx
                ret
 
@@ -3703,7 +3719,7 @@ getfssec:
 .send_ack:     push cx                         ; <D> Retry count
 
                mov eax,[si+tftp_filepos]
-               shr eax,LOG_TFTP_BLOCKSIZE
+               shr eax,TFTP_BLOCKSIZE_LG2
                xchg ah,al                      ; Network byte order
                call ack_packet                 ; Send ACK
 
@@ -3762,7 +3778,7 @@ getfssec:
                jne .wait_data                  ; Then wait for something else
 
                mov eax,[si+tftp_filepos]
-               shr eax,LOG_TFTP_BLOCKSIZE
+               shr eax,TFTP_BLOCKSIZE_LG2
                inc ax                          ; Which packet are we waiting for?
        
                xchg ah,al                      ; Network byte order
@@ -4288,7 +4304,7 @@ VKernelCtr        dw 0                    ; Number of registered vkernels
 ForcePrompt    dw 0                    ; Force prompt
 AllowImplicit   dw 1                    ; Allow implicit kernels
 SerialPort     dw 0                    ; Serial port base (or 0 for no serial port)
-MySocket       dw 32768                ; Local UDP socket counter
+NextSocket     dw 49152                ; Counter for allocating socket numbers
 A20List                dw a20_dunno, a20_none, a20_bios, a20_kbc, a20_fast
 A20DList       dw a20d_dunno, a20d_none, a20d_bios, a20d_kbc, a20d_fast
 A20Type                dw A20_DUNNO            ; A20 type unknown