opcode.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

\&
\&    $yes = opset_can($opset, @ops)      true if $opset has all @ops set
\&
\&    @diff = opset_diff($opset1, $opset2) => (\*(Aqfoo\*(Aq, \*(Aq!bar\*(Aq, ...)
.Ve
.SH "Predefined Opcode Tags"
.IX Header "Predefined Opcode Tags"
.IP ":base_core" 5
.IX Item ":base_core"
.Vb 1
\&    null stub scalar pushmark wantarray const defined undef
\&
\&    rv2sv sassign
\&
\&    rv2av aassign aelem aelemfast aslice av2arylen
\&
\&    rv2hv helem hslice each values keys exists delete
\&
\&    preinc i_preinc predec i_predec postinc i_postinc postdec i_postdec
\&    int hex oct abs pow multiply i_multiply divide i_divide
\&    modulo i_modulo add i_add subtract i_subtract
\&
\&    left_shift right_shift bit_and bit_xor bit_or negate i_negate
\&    not complement
\&
\&    lt i_lt gt i_gt le i_le ge i_ge eq i_eq ne i_ne ncmp i_ncmp
\&    slt sgt sle sge seq sne scmp
\&
\&    substr vec stringify study pos length index rindex ord chr
\&
\&    ucfirst lcfirst uc lc quotemeta trans chop schop chomp schomp
\&
\&    match split qr
\&
\&    list lslice splice push pop shift unshift reverse
\&
\&    cond_expr flip flop andassign orassign dorassign and or dor xor
\&
\&    warn die lineseq nextstate scope enter leave setstate
\&
\&    rv2cv anoncode prototype
\&
\&    entersub leavesub leavesublv return method method_named \-\- XXX loops via recursion?
\&
\&    leaveeval \-\- needed for Safe to operate, is safe without entereval
.Ve
.IP ":base_mem" 5
.IX Item ":base_mem"
These memory related ops are not included in :base_core because they
can easily be used to implement a resource attack (e.g., consume all
available memory).
.Sp
.Vb 1
\&    concat repeat join range
\&
\&    anonlist anonhash
.Ve
.Sp
Note that despite the existence of this optag a memory resource attack
may still be possible using only :base_core ops.
.Sp
Disabling these ops is a \fIvery\fR heavy handed way to attempt to prevent
a memory resource attack. It's probable that a specific memory limit
mechanism will be added to perl in the near future.
.IP ":base_loop" 5
.IX Item ":base_loop"
These loop ops are not included in :base_core because they can easily be
used to implement a resource attack (e.g., consume all available \s-1CPU\s0 time).
.Sp
.Vb 6
\&    grepstart grepwhile
\&    mapstart mapwhile
\&    enteriter iter
\&    enterloop leaveloop unstack
\&    last next redo
\&    goto
.Ve
.IP ":base_io" 5
.IX Item ":base_io"
These ops enable \fIfilehandle\fR (rather than filename) based input and
output. These are safe on the assumption that only pre-existing
filehandles are available for use.  Usually, to create new filehandles
other ops such as open would need to be enabled, if you don't take into
account the magical open of \s-1ARGV\s0.
.Sp
.Vb 1
\&    readline rcatline getc read
\&
\&    formline enterwrite leavewrite
\&
\&    print say sysread syswrite send recv
\&
\&    eof tell seek sysseek
\&
\&    readdir telldir seekdir rewinddir
.Ve
.IP ":base_orig" 5
.IX Item ":base_orig"
These are a hotchpotch of opcodes still waiting to be considered
.Sp
.Vb 1
\&    gvsv gv gelem
\&
\&    padsv padav padhv padany
\&
\&    once
\&
\&    rv2gv refgen srefgen ref
\&
\&    bless \-\- could be used to change ownership of objects (reblessing)
\&
\&    pushre regcmaybe regcreset regcomp subst substcont
\&
\&    sprintf prtf \-\- can core dump
\&
\&    crypt
\&
\&    tie untie
\&
\&    dbmopen dbmclose
\&    sselect select
\&    pipe_op sockpair
\&
\&    getppid getpgrp setpgrp getpriority setpriority localtime gmtime
\&
\&    entertry leavetry \-\- can be used to \*(Aqhide\*(Aq fatal errors
\&
\&    entergiven leavegiven
\&    enterwhen leavewhen
\&    break continue
\&    smartmatch
\&
\&    custom \-\- where should this go
.Ve
.IP ":base_math" 5
.IX Item ":base_math"
These ops are not included in :base_core because of the risk of them being
used to generate floating point exceptions (which would have to be caught
using a \f(CW$SIG\fR{\s-1FPE\s0} handler).
.Sp
.Vb 1
\&    atan2 sin cos exp log sqrt
.Ve
.Sp
These ops are not included in :base_core because they have an effect
beyond the scope of the compartment.
.Sp
.Vb 1
\&    rand srand
.Ve
.IP ":base_thread" 5
.IX Item ":base_thread"
These ops are related to multi-threading.
.Sp
.Vb 1
\&    lock
.Ve
.IP ":default" 5
.IX Item ":default"
A handy tag name for a \fIreasonable\fR default set of ops.  (The current ops
allowed are unstable while development continues. It will change.)
.Sp
.Vb 1
\&    :base_core :base_mem :base_loop :base_orig :base_thread
.Ve
.Sp
This list used to contain :base_io prior to Opcode 1.07.
.Sp
If safety matters to you (and why else would you be using the Opcode module?)
then you should not rely on the definition of this, or indeed any other, optag!
.IP ":filesys_read" 5
.IX Item ":filesys_read"
.Vb 1
\&    stat lstat readlink
\&
\&    ftatime ftblk ftchr ftctime ftdir fteexec fteowned fteread
\&    ftewrite ftfile ftis ftlink ftmtime ftpipe ftrexec ftrowned
\&    ftrread ftsgid ftsize ftsock ftsuid fttty ftzero ftrwrite ftsvtx
\&
\&    fttext ftbinary
\&
\&    fileno
.Ve
.IP ":sys_db" 5
.IX Item ":sys_db"
.Vb 4
\&    ghbyname ghbyaddr ghostent shostent ehostent      \-\- hosts
\&    gnbyname gnbyaddr gnetent snetent enetent         \-\- networks
\&    gpbyname gpbynumber gprotoent sprotoent eprotoent \-\- protocols
\&    gsbyname gsbyport gservent sservent eservent      \-\- services
\&
\&    gpwnam gpwuid gpwent spwent epwent getlogin       \-\- users
\&    ggrnam ggrgid ggrent sgrent egrent                \-\- groups
.Ve
.IP ":browse" 5
.IX Item ":browse"
A handy tag name for a \fIreasonable\fR default set of ops beyond the
:default optag.  Like :default (and indeed all the other optags) its
current definition is unstable while development continues. It will change.
.Sp
The :browse tag represents the next step beyond :default. It it a
superset of the :default ops and adds :filesys_read the :sys_db.
The intent being that scripts can access more (possibly sensitive)
information about your system but not be able to change it.
.Sp
.Vb 1
\&    :default :filesys_read :sys_db
.Ve
.IP ":filesys_open" 5
.IX Item ":filesys_open"
.Vb 2
\&    sysopen open close
\&    umask binmode
\&
\&    open_dir closedir \-\- other dir ops are in :base_io
.Ve
.IP ":filesys_write" 5
.IX Item ":filesys_write"
.Vb 1
\&    link unlink rename symlink truncate
\&
\&    mkdir rmdir
\&
\&    utime chmod chown
\&
\&    fcntl \-\- not strictly filesys related, but possibly as dangerous?
.Ve
.IP ":subprocess" 5
.IX Item ":subprocess"
.Vb 1
\&    backtick system
\&
\&    fork
\&
\&    wait waitpid
\&
\&    glob \-\- access to Cshell via <\`rm *\`>
.Ve
.IP ":ownprocess" 5
.IX Item ":ownprocess"
.Vb 1
\&    exec exit kill
\&
\&    time tms \-\- could be used for timing attacks (paranoid?)
.Ve
.IP ":others" 5
.IX Item ":others"
This tag holds groups of assorted specialist opcodes that don't warrant
having optags defined for them.
.Sp
SystemV Interprocess Communications:
.Sp
.Vb 1
\&    msgctl msgget msgrcv msgsnd
\&
\&    semctl semget semop
\&
\&    shmctl shmget shmread shmwrite
.Ve
.IP ":load" 5
.IX Item ":load"
This tag holds opcodes related to loading modules and getting information
about calling environment and args.
.Sp
.Vb 2
\&    require dofile 
\&    caller
.Ve
.IP ":still_to_be_decided" 5
.IX Item ":still_to_be_decided"
.Vb 2
\&    chdir
\&    flock ioctl
\&
\&    socket getpeername ssockopt
\&    bind connect listen accept shutdown gsockopt getsockname
\&
\&    sleep alarm \-\- changes global timer state and signal handling
\&    sort \-\- assorted problems including core dumps
\&    tied \-\- can be used to access object implementing a tie
\&    pack unpack \-\- can be used to create/use memory pointers
\&
\&    entereval \-\- can be used to hide code from initial compile
\&
\&    reset
\&
\&    dbstate \-\- perl \-d version of nextstate(ment) opcode
.Ve
.IP ":dangerous" 5
.IX Item ":dangerous"
This tag is simply a bucket for opcodes that are unlikely to be used via
a tag name but need to be tagged for completeness and documentation.
.Sp
.Vb 1
\&    syscall dump chroot
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
ops \*(-- perl pragma interface to Opcode module.
.PP
Safe \*(-- Opcode and namespace limited execution compartments
.SH "AUTHORS"
.IX Header "AUTHORS"
Originally designed and implemented by Malcolm Beattie,
[e-mail] as part of Safe version 1.
.PP
Split out from Safe module version 1, named opcode tags and other
changes added by Tim Bunce.