Date: Thu, 13 Mar 2008 10:10:01 -0600 From: "Andrew Falanga" <af300wsm@gmail.com> To: "FreeBSD Questions" <freebsd-questions@freebsd.org> Subject: Network programming question Message-ID: <340a29540803130910l2a5badacxe50cd81ace87e1f7@mail.gmail.com>
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Hi, I'd like to know why the inet_pton(3) doesn't fill in the address family of the proper structure passed into it. I'm at a complete loss for why. Here's the prototype: int inet_pton(int af, const char * restrict src, void * restrict dst); Three arguments only. The address family, hm, I'm passing it in; the address string in printable ASCII text, and a void pointer to the address structure to put the address into, presumably one of the sockaddr_* family structures for AF_INET or AF_INET6 (further, the man page says that this function is only valid for these two families now anyway). >From some coding for a program, I did find that this function, inet_pton(3), *does* in fact mangle the sin_family member of the sockaddr_in structure, so why not "mangle" it to what it should be? I was doing something like this: // valid code above sockaddr_in sa; sa.sin_family = AF_INET; sa.sin_port = htons(3252); inet_pton(AF_INET, "192.168.0.1", &sa); sendto(sa, msg, strlen(msg), 0, (struct sockaddr*)&sa, sizeof(sa)); The call to sendto is wrapped in an if an was failing for errno code 47, Address family not supported by protocol (I was using UDP). I changed the assignment of AF_INET to the sa.sin_family member to *after* the call to inet_pton(3) and suddenly everything worked. Why? Since the address family was used by inet_pton(3) to figure out how to read the address and assign it to sa.sin_addr.s_addr, why not simply assign AF_INET to the address family member in inet_pton(3)? I'm not trying to be argumentative. I'm just curious. It seems like redundancy. I've used the address family to tell inet_pton(3) how to operate, and then this function can't assign it to the sockaddr_in structure passed to it? This makes little sense. In case it's because I'm using older FBSD libraries that had a flaw fixed, I'm using FreeBSD 6.2-RELEASE-p4. Is this because that's how POSIX defined it to work? Is this the right venue or should I try one of the other mailing lists? Thanks, Andy -- A: Because it messes up the order in which people normally read text. Q: Why is it such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet and in e-mail?
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