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From: stephen farrell <spfarrel@meno.uchicago.edu>
Subject: Re: How to open a socket under FreeBSD?
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References: <GORSKI.96Oct26172702@axiom.www.xxx>
Date: Mon, 28 Oct 1996 02:53:03 GMT
gorski@cips01.physik.uni-bonn.de writes:
>
>
>
> I want to open a socket under FreeBSD, but all the examples I've found for BSD
> use the 'struct sockaddr_in'. FreeBSD needs 'struct sockaddr'! I'm not familiar
> with sockets. How can I open a socket under FreeBSD?
> I've seen something like connect(sock, (struct sockaddr *) &name, sizeof(name))
> in some source codes. Is that the way? This seems to be wrong for me.
>
> Thanks for help (links to resources,dox,books,etc. are welcome).
>
you need to cast sockaddr into a sockaddr_in. it just works -- as far
as i know it's magic.
>
>
>
> None working example (from PSD:20):
> --------------------------------------------------------------------------------
> #include <sys/types.h>
> #include <sys/socket.h>
> #include <netinet/in.h>
> #include <stdio.h>
>
> /*
> * In the included file <netinet/in.h> a sockaddr_in is defined as follows:
> * struct sockaddr_in {
> * short sin_family;
> * u_short sin_port;
> * struct in_addr sin_addr;
> * char sin_zero[8];
> * };
> *
> * This program creates a datagram socket, binds a name to it, then reads
> * from the socket.
> */
> main()
> {
> int sock, length;
> struct sockaddr_in name;
> char buf[1024];
>
> /* Create socket from which to read. */
> sock = socket(AF_INET, SOCK_DGRAM, 0);
> if (sock < 0) {
> perror("opening datagram socket");
> exit(1);
> }
> /* Create name with wildcards. */
> name.sin_family = AF_INET;
> name.sin_addr.s_addr = INADDR_ANY;
> name.sin_port = 0;
> if (bind(sock, &name, sizeof(name))) {
> perror("binding datagram socket");
> exit(1);
> }
> /* Find assigned port value and print it out. */
> length = sizeof(name);
> if (getsockname(sock, &name, &length)) {
> perror("getting socket name");
> exit(1);
> }
> printf("Socket has port #%d\n", ntohs(name.sin_port));
> /* Read from the socket */
> if (read(sock, buf, 1024) < 0)
> perror("receiving datagram packet");
> printf("-->%s\n", buf);
> close(sock);
> }
> --------------------------------------------------------------------------------