[PATCH] vsprintf: automatic parameters for %pIS via 'a'

From: Jason A. Donenfeld
Date: Fri Feb 05 2016 - 08:36:32 EST


This patch adds a variable 'a' which indicates that the 'p',
'f', and 's' options should active depending on whether
or not those parameters are actually valid inside the
passed sockaddr.

Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
---
Documentation/printk-formats.txt | 7 +++++--
lib/test_printf.c | 23 +++++++++++++++++++++++
lib/vsprintf.c | 19 +++++++++++++++++--
3 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index 5d1128b..5c45db4 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -193,7 +193,7 @@ IPv4/IPv6 addresses (generic, with port, flowinfo, scope):
%piS 001.002.003.004 or 00010002000300040005000600070008
%pISc 1.2.3.4 or 1:2:3:4:5:6:7:8
%pISpc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345
- %p[Ii]S[pfschnbl]
+ %p[Ii]S[pfsachnbl]

For printing an IP address without the need to distinguish whether it's
of type AF_INET or AF_INET6, a pointer to a valid 'struct sockaddr',
@@ -201,7 +201,10 @@ IPv4/IPv6 addresses (generic, with port, flowinfo, scope):

The additional 'p', 'f', and 's' specifiers are used to specify port
(IPv4, IPv6), flowinfo (IPv6) and scope (IPv6). Ports have a ':' prefix,
- flowinfo a '/' and scope a '%', each followed by the actual value.
+ flowinfo a '/' and scope a '%', each followed by the actual value. If 'a'
+ is given, 'p', 'f', and 's', when also specified, are only printed
+ depending on whether or not the socketaddr has a non-zero port,
+ flowinfo, and scope.

In case of an IPv6 address the compressed IPv6 address as described by
http://tools.ietf.org/html/rfc5952 is being used if the additional
diff --git a/lib/test_printf.c b/lib/test_printf.c
index 4f6ae60..c3f975e 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -16,6 +16,7 @@
#include <linux/dcache.h>
#include <linux/socket.h>
#include <linux/in.h>
+#include <linux/in6.h>

#define BUF_SIZE 256
#define PAD_SIZE 16
@@ -301,11 +302,33 @@ ip4(void)
test("127.000.000.001|127.0.0.1", "%piS|%pIS", &sa, &sa);
sa.sin_addr.s_addr = cpu_to_be32(0x01020304);
test("001.002.003.004:12345|1.2.3.4:12345", "%piSp|%pISp", &sa, &sa);
+ test("1.2.3.4:12345", "%pISpa", &sa);
+ test("1.2.3.4", "%pISa", &sa);
+ sa.sin_port = 0;
+ test("1.2.3.4", "%pISpa", &sa);
}

static void __init
ip6(void)
{
+ struct sockaddr_in6 sa = { 0 };
+
+ sa.sin6_family = AF_INET6;
+ sa.sin6_port = cpu_to_be16(12345);
+ sa.sin6_addr.in6_u.u6_addr16[0] = cpu_to_be16(0xabcd);
+ sa.sin6_addr.in6_u.u6_addr16[7] = cpu_to_be16(0x1234);
+ sa.sin6_flowinfo = cpu_to_be32(20);
+ sa.sin6_scope_id = 98;
+
+ test("[abcd::1234]:12345", "%pISpca", &sa);
+ test("[abcd::1234]:12345/20", "%pISpfca", &sa);
+ test("[abcd::1234]:12345/20%98", "%pISpfsca", &sa);
+ sa.sin6_flowinfo = 0;
+ test("[abcd::1234]:12345%98", "%pISpsfca", &sa);
+ sa.sin6_port = 0;
+ test("[abcd::1234]%98", "%pISpfsca", &sa);
+ sa.sin6_scope_id = 0;
+ test("abcd::1234", "%pISpfsca", &sa);
}

static void __init
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 48ff9c3..80d8ce5 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1145,7 +1145,7 @@ static noinline_for_stack
char *ip6_addr_string_sa(char *buf, char *end, const struct sockaddr_in6 *sa,
struct printf_spec spec, const char *fmt)
{
- bool have_p = false, have_s = false, have_f = false, have_c = false;
+ bool have_p = false, have_s = false, have_f = false, have_c = false, have_a = false;
char ip6_addr[sizeof("[xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255]") +
sizeof(":12345") + sizeof("/123456789") +
sizeof("%1234567890")];
@@ -1169,9 +1169,18 @@ char *ip6_addr_string_sa(char *buf, char *end, const struct sockaddr_in6 *sa,
case 'c':
have_c = true;
break;
+ case 'a':
+ have_a = true;
+ break;
}
}

+ if (have_a) {
+ have_p = have_p && sa->sin6_port;
+ have_s = have_s && sa->sin6_scope_id;
+ have_f = have_f && (sa->sin6_flowinfo & IPV6_FLOWINFO_MASK);
+ }
+
if (have_p || have_s || have_f) {
*p = '[';
off = 1;
@@ -1207,7 +1216,7 @@ static noinline_for_stack
char *ip4_addr_string_sa(char *buf, char *end, const struct sockaddr_in *sa,
struct printf_spec spec, const char *fmt)
{
- bool have_p = false;
+ bool have_p = false, have_a = false;
char *p, ip4_addr[sizeof("255.255.255.255") + sizeof(":12345")];
char *pend = ip4_addr + sizeof(ip4_addr);
const u8 *addr = (const u8 *) &sa->sin_addr.s_addr;
@@ -1225,9 +1234,15 @@ char *ip4_addr_string_sa(char *buf, char *end, const struct sockaddr_in *sa,
case 'b':
fmt4[2] = *fmt;
break;
+ case 'a':
+ have_a = true;
+ break;
}
}

+ if (have_a)
+ have_p = have_p && sa->sin_port;
+
p = ip4_string(ip4_addr, addr, fmt4);
if (have_p) {
*p++ = ':';
--
2.7.0