Python and UDP sockets

[Zunbeltz Izaola]

Hi!

I want to port a small socket aplication (in C) to Python.
The server is writen in C, and it expected to recibe and C struct
like this


struct tag_instruccion
{
unsigned int Handle __attribute__ ((aligned(1)));
int Codigo __attribute__ ((aligned(1)));
double Param[10] __attribute__ ((aligned(1)));
char Comando[_MAX_PATH] __attribute__ ((aligned(1))) ;
char Instruc[_MAX_PATH] __attribute__ ((aligned(1))) ;
};

I know that the functions for sockets are essentialy those that are in
C (BSD sockets), but i don't know how to send this kind of struct
directly.

One of the function to send a socket is this

EnviaMensaje(SO CKET iSocket,int port,char *host, instruccion *Instruccion)
{
struct sockaddr_in siSockAddr;
int iRc;
CodigoMensaje resultado;

if (iSocket != INVALID_SOCKET)
{
memset((char *)&siSockAddr,0 ,sizeof(siSockA ddr));
siSockAddr.sin_ family = AF_INET;
siSockAddr.sin_ port = htons(port);
siSockAddr.sin_ addr.s_addr = inet_addr(host) ;
iRc = sendto(iSocket, (char const FAR *)Instruccion,s izeof(instrucci on),0,(struct sockaddr FAR *)(&siSockAddr) ,sizeof(siSockA ddr));
}
return iRc;
}

Can someone help me?
Thanks in advance

Zunbeltz Izaola

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[Alex Martelli]

Re: Python and UDP sockets

Zunbeltz Izaola wrote:
...[color=blue]
> C (BSD sockets), but i don't know how to send this kind of struct
> directly.[/color]

You transform the tuple of field values into a string with struct.pack
and send the string. And vv in receiving. See:

http://www.python.org/doc/current/lib/module-struct.html

Alex

[Werner Schiendl]

Re: Python and UDP sockets

Hi,

look at the struct module from the python standard library.

in particular, struct.pack allows to format your data as required.

hth
Werner


Zunbeltz Izaola wrote:
[color=blue]
> Hi!
>
> I want to port a small socket aplication (in C) to Python.
> The server is writen in C, and it expected to recibe and C struct
> like this
>
>
> struct tag_instruccion
> {
> unsigned int Handle __attribute__ ((aligned(1)));
> int Codigo __attribute__ ((aligned(1)));
> double Param[10] __attribute__ ((aligned(1)));
> char Comando[_MAX_PATH] __attribute__ ((aligned(1))) ;
> char Instruc[_MAX_PATH] __attribute__ ((aligned(1))) ;
> };
>
> I know that the functions for sockets are essentialy those that are in
> C (BSD sockets), but i don't know how to send this kind of struct
> directly.
>
> One of the function to send a socket is this
>
> EnviaMensaje(SO CKET iSocket,int port,char *host, instruccion *Instruccion)
> {
> struct sockaddr_in siSockAddr;
> int iRc;
> CodigoMensaje resultado;
>
> if (iSocket != INVALID_SOCKET)
> {
> memset((char *)&siSockAddr,0 ,sizeof(siSockA ddr));
> siSockAddr.sin_ family = AF_INET;
> siSockAddr.sin_ port = htons(port);
> siSockAddr.sin_ addr.s_addr = inet_addr(host) ;
> iRc = sendto(iSocket, (char const FAR *)Instruccion,s izeof(instrucci on),0,(struct sockaddr FAR *)(&siSockAddr) ,sizeof(siSockA ddr));
> }
> return iRc;
> }
>
> Can someone help me?
> Thanks in advance
>
> Zunbeltz Izaola
>[/color]

[Zunbeltz Izaola]

Re: Python and UDP sockets

Werner Schiendl <n17999950.temp .werner@neverbo x.com> writes:

Hi

Thanks for the point. I'm using struct and it is working well.
Thanks again

Zunbeltz
[color=blue]
> Hi,
>
> look at the struct module from the python standard library.
>
> in particular, struct.pack allows to format your data as required.
>
> hth
> Werner
>
>
> Zunbeltz Izaola wrote:
>[color=green]
> > Hi!
> > I want to port a small socket aplication (in C) to Python.
> > The server is writen in C, and it expected to recibe and C struct
> > like this struct tag_instruccion
> > {
> > unsigned int Handle __attribute__ ((aligned(1)));
> > int Codigo __attribute__ ((aligned(1)));
> > double Param[10] __attribute__ ((aligned(1)));
> > char Comando[_MAX_PATH] __attribute__ ((aligned(1))) ;
> > char Instruc[_MAX_PATH] __attribute__ ((aligned(1))) ;
> > };
> > I know that the functions for sockets are essentialy those that are
> > in
> > C (BSD sockets), but i don't know how to send this kind of struct
> > directly.
> > One of the function to send a socket is this
> > EnviaMensaje(SO CKET iSocket,int port,char *host, instruccion
> > *Instruccion)
> > {
> > struct sockaddr_in siSockAddr;
> > int iRc;
> > CodigoMensaje resultado;
> > if (iSocket != INVALID_SOCKET)
> > {
> > memset((char *)&siSockAddr,0 ,sizeof(siSockA ddr));
> > siSockAddr.sin_ family = AF_INET;
> > siSockAddr.sin_ port = htons(port);
> > siSockAddr.sin_ addr.s_addr = inet_addr(host) ;
> > iRc = sendto(iSocket, (char const FAR *)Instruccion,s izeof(instrucci on),0,(struct sockaddr FAR *)(&siSockAddr) ,sizeof(siSockA ddr));
> > }
> > return iRc;
> > }
> > Can someone help me?
> > Thanks in advance
> > Zunbeltz Izaola
> >[/color]
>[/color]

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