From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: [PATCH net-next 1/2] lib: vsprintf: add IPv4/v6 generic %pig/%pIg format specifier Date: Wed, 26 Jun 2013 13:27:19 -0400 Message-ID: <51CB2477.6070903@gmail.com> References: <1372266073-11998-1-git-send-email-dborkman@redhat.com> <1372266073-11998-2-git-send-email-dborkman@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, netdev@vger.kernel.org, linux-sctp@vger.kernel.org To: Daniel Borkmann Return-path: Received: from mail-gh0-f181.google.com ([209.85.160.181]:53463 "EHLO mail-gh0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751841Ab3FZR12 (ORCPT ); Wed, 26 Jun 2013 13:27:28 -0400 In-Reply-To: <1372266073-11998-2-git-send-email-dborkman@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On 06/26/2013 01:01 PM, Daniel Borkmann wrote: > In order to avoid making code that deals with printing both, IPv4 and > IPv6 addresses, unnecessary complicated as for example ... > > if (sa.sa_family == AF_INET6) > printk("... %pI6 ...", sin6_addr); > else > printk("... %pI4 ...", sin_addr.s_addr); > > ... it would be better to introduce a format specifier that can deal > with those kind of situations internally; just as we have a "struct > sockaddr" for generic mapping into "struct sockaddr_in" or "struct > sockaddr_in6" as e.g. done in "union sctp_addr". Then, we could > reduce the above statement into something like: > > printk("... %pIg ..", &sockaddr); > > While we're at it, support for both %pig/%pIg, where 'g' stands for > generic, comes for free. In case our pointer is NULL, pointer() then > deals with that already at an earlier point in time internally. > > Likely, there are many other areas than just SCTP in the kernel to make > use of this extension as well. > > Signed-off-by: Daniel Borkmann > --- > lib/vsprintf.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) I think you should also update Documentation/printk-formats.txt -vlad > > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > index e149c64..7243742 100644 > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -1004,10 +1004,10 @@ int kptr_restrict __read_mostly; > * - 'MF' For a 6-byte MAC FDDI address, it prints the address > * with a dash-separated hex notation > * - '[mM]R' For a 6-byte MAC address, Reverse order (Bluetooth) > - * - 'I' [46] for IPv4/IPv6 addresses printed in the usual way > + * - 'I' [46g] for IPv4/IPv6 addresses printed in the usual way > * IPv4 uses dot-separated decimal without leading 0's (1.2.3.4) > * IPv6 uses colon separated network-order 16 bit hex with leading 0's > - * - 'i' [46] for 'raw' IPv4/IPv6 addresses > + * - 'i' [46g] for 'raw' IPv4/IPv6 addresses > * IPv6 omits the colons (01020304...0f) > * IPv4 uses dot-separated decimal with leading 0's (010.123.045.006) > * - '[Ii]4[hnbl]' IPv4 addresses in host, network, big or little endian order > @@ -1093,6 +1093,18 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, > return ip6_addr_string(buf, end, ptr, spec, fmt); > case '4': > return ip4_addr_string(buf, end, ptr, spec, fmt); > + case 'g': > + { > + const struct sockaddr *sa = ptr; > + > + if (sa->sa_family == AF_INET6) { > + ptr = &((struct sockaddr_in6 *) sa)->sin6_addr; > + return ip6_addr_string(buf, end, ptr, spec, fmt); > + } else { > + ptr = &((struct sockaddr_in *) sa)->sin_addr.s_addr; > + return ip4_addr_string(buf, end, ptr, spec, fmt); > + } > + } > } > break; > case 'U': > @@ -1370,6 +1382,8 @@ qualifier: > * %pI6 print an IPv6 address with colons > * %pi6 print an IPv6 address without colons > * %pI6c print an IPv6 address as specified by RFC 5952 > + * %pIg depending on sa_family of 'struct sockaddr *' switch to %pI6/%pI4 > + * %pig depending on sa_family of 'struct sockaddr *' switch to %pi6/%pi4 > * %pU[bBlL] print a UUID/GUID in big or little endian using lower or upper > * case. > * %*ph[CDN] a variable-length hex string with a separator (supports up to 64 >