use Perl

• microperl & sockets (Score:1)

  by yoleg (7730)

  Hello clkao, I am also interested in using Microperl with some networking functions. How did you port the functionalities from Socket.pm to Perl? Did you write them in C? from what I read in your post, you seem to have rewritten in Perl... When you write that it's not such a good thing to do it from perl because it's platform-dependent, does this refer to the CPU type or to the OS itself. My goal is to add some local UNIX socket functionality (sockaddr_un) inside Microperl to be able to accept incoming co
  • Re:microperl & sockets (Score:1)

    by yoleg (7730) on 2007.03.09 11:22 (#53623)

    Hello,
    
    I finally could make it work by using the following code (that allows my code to be rather platform-independant, if I fill in properly the first bunch of variables):
    
    my $PF_UNIX=1;
my $AF_UNIX=$PF_UNIX;
my $SOCK_STREAM=2;   # 1 for ix86, 2 for MIPS
my $SOMAXCONN=128;
my $sun_path_SIZE=2;
my $sun_family_SIZE=108;



#my $uaddr = sockaddr_un($SOCKFILE);   # Create a UNIX socket (local)... not used because this requires Socket.pm... instead, we will pack the sockaddr_un structure manually as done below


sub is_little_endian {
   return (unpack('c', pack('s', 1)));
}

my $sun_path_pack = "I";
($sun_path_SIZE == 1) && ($sun_path_pack = "C");
($sun_path_SIZE == 2) && ($sun_path_pack = (is_little_endian() ? "v" : "n"));
($sun_path_SIZE == 4) && ($sun_path_pack = (is_little_endian() ? "V" : "N"));

# This contains $AF_UNIX (it is the .sun_family field of sockaddr_un) + .sun_path field of sockaddr_un
$uaddr = pack($sun_path_pack . " a" . $sun_family_SIZE, $AF_UNIX, $SOCKFILE);
    
    
    My $uaddr then contains the right struct to create the socket...
    
    $SOMAXCONN is used later to avoid depending on Socket.pm only for SOMAXCONN
    The rest of the variables:
    $PF_UNIX=1;
$SOCK_STREAM=2;
$SOMAXCONN=128;
...are taken from the #defines of my cross-compiler, and:
    $sun_path_SIZE=2;
$sun_family_SIZE=108;
...are extracted from the size of the fields inside sockaddr_un.
    
    To automate the discovery of the above variables, the following C file can be cross-compiled to dump the right variables on the target environment (a MIPS for me):
    
    #include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>

#ifndef UNIX_PATH_LEN
#define UNIX_PATH_LEN (sizeof(((struct sockaddr_un *) 0)->sun_path))
#endif

int main (int argc, char **argv) {
   
   struct sockaddr_un *sample_un_sock;
   
#ifdef SOCK_STREAM
   printf("SOCK_STREAM=%u\n", SOCK_STREAM);
#endif
#ifdef SOMAXCONN
   printf("SOMAXCONN=%u\n", SOMAXCONN);
#endif
#ifdef PF_UNIX
   printf("PF_UNIX=%u\n", PF_UNIX);
#endif
   printf("OFFSET for .sun_path in sockaddr_un=%u\n", (void *)&(sample_un_sock->sun_path) - (void *)sample_un_sock);
   printf("SIZE for .sun_path in sockaddr_un=%u\n", UNIX_PATH_LEN);
   printf("OFFSET for .sun_family in sockaddr_un=%u\n", (void *)&(sample_un_sock->sun_family) - (void *)sample_un_sock);
   printf("SIZE for .sun_family in sockaddr_un=%u\n", sizeof(sample_un_sock->sun_family));
   return 0;
}

    Also, for cross-compiling Perl (using miniperl instead of microperl), there is a nice text describing a cross-Configure (using ssh and scp for example), to generate a config.sh matching with a remote target (for further cross-compilation).
    This can be found in the Cross-compilation section of the ./INSTALL text file (in perl-5.8.8)
    

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