Re: [BUG?] ipv6.7: SOCK_DGRAM can accept different protocols?

On Fri, Sep 17, 2021 at 8:13 AM Alejandro Colomar
[off-list ref] wrote:

Hi,

Reading a stackoverflow question
<https://stackoverflow.com/questions/51996808/do-we-need-to-specify-protocol-when-type-is-sock-dgram-or-sock-stream-in-soc>
it noted that, while ip(7) notes that protocol can be left as 0 for both
SOCK_STREAM and SOCK_DGRAM, ipv6(7) is misleading and seems to suggest
that protocol may be significant for SOCK_DGRAM (at least in the SYNOPSIS).

It can be left as 0, but, I think, IPPROTO_UDPLITE (at least) can be
specified in both cases, if the caller wishes so (as well as
IPPROTO_MPTCP/IPPROTO_SCTP for SOCK_STREAM, and some other, more
obscure protocols, like DCCP or L2TP).

I guess that's not true, and it can be left as 0, but since I don't
know, I'll ask.

Thanks,

Alex


--

IP(7)                Linux Programmer's Manual               IP(7)

NAME
        ip - Linux IPv4 protocol implementation

SYNOPSIS
        #include <sys/socket.h>
        #include <netinet/in.h>
        #include <netinet/ip.h> /* superset of previous */

        tcp_socket = socket(AF_INET, SOCK_STREAM, 0);
        udp_socket = socket(AF_INET, SOCK_DGRAM, 0);
        raw_socket = socket(AF_INET, SOCK_RAW, protocol);


--

IPV6(7)              Linux Programmer's Manual             IPV6(7)

NAME
        ipv6 - Linux IPv6 protocol implementation

SYNOPSIS
        #include <sys/socket.h>
        #include <netinet/in.h>

        tcp6_socket = socket(AF_INET6, SOCK_STREAM, 0);
        raw6_socket = socket(AF_INET6, SOCK_RAW, protocol);
        udp6_socket = socket(AF_INET6, SOCK_DGRAM, protocol);


--
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/

-- 
Eugene Syromyatnikov
mailto:evgsyr@gmail.com
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