netdev - Re: [PATCH rfc 1/4] net/utils: generic inet_pton_with

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Message-ID: <6c2a4f67-ede6-0ee1-5a90-14023994d029@grimberg.me>
Date:   Tue, 21 Feb 2017 23:18:04 +0200
From:   Sagi Grimberg <sagi@...mberg.me>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     linux-nvme@...ts.infradead.org, linux-rdma@...r.kernel.org,
        target-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH rfc 1/4] net/utils: generic inet_pton_with_scope helper



On 19/02/17 19:15, Christoph Hellwig wrote:
> On Thu, Feb 16, 2017 at 07:43:34PM +0200, Sagi Grimberg wrote:
>> Several locations in the stack need to handle ipv4/ipv6
>> (with scope) and port strings conversion to sockaddr.
>> Add a helper that takes either AF_INET, AF_INET6 or
>> AF_UNSPEC (for wildcard) to centralize this handling.
>>
>> Suggested-by: Christoph Hellwig <hch@....de>
>> Signed-off-by: Sagi Grimberg <sagi@...mberg.me>
>> ---
>>  include/linux/inet.h |  6 ++++
>>  net/core/utils.c     | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 97 insertions(+)
>>
>> diff --git a/include/linux/inet.h b/include/linux/inet.h
>> index 4cca05c9678e..636ebe87e6f8 100644
>> --- a/include/linux/inet.h
>> +++ b/include/linux/inet.h
>> @@ -43,6 +43,8 @@
>>  #define _LINUX_INET_H
>>
>>  #include <linux/types.h>
>> +#include <net/net_namespace.h>
>> +#include <linux/socket.h>
>>
>>  /*
>>   * These mimic similar macros defined in user-space for inet_ntop(3).
>> @@ -54,4 +56,8 @@
>>  extern __be32 in_aton(const char *str);
>>  extern int in4_pton(const char *src, int srclen, u8 *dst, int delim, const char **end);
>>  extern int in6_pton(const char *src, int srclen, u8 *dst, int delim, const char **end);
>> +
>> +extern int inet_pton_with_scope(struct net *net, unsigned short af,
>> +		const char *src, const char *port, struct sockaddr_storage *addr);
>> +
>>  #endif	/* _LINUX_INET_H */
>> diff --git a/net/core/utils.c b/net/core/utils.c
>> index 6592d7bbed39..8f15d016c64a 100644
>> --- a/net/core/utils.c
>> +++ b/net/core/utils.c
>> @@ -26,9 +26,11 @@
>>  #include <linux/percpu.h>
>>  #include <linux/init.h>
>>  #include <linux/ratelimit.h>
>> +#include <linux/socket.h>
>>
>>  #include <net/sock.h>
>>  #include <net/net_ratelimit.h>
>> +#include <net/ipv6.h>
>>
>>  #include <asm/byteorder.h>
>>  #include <linux/uaccess.h>
>> @@ -300,6 +302,95 @@ int in6_pton(const char *src, int srclen,
>>  }
>>  EXPORT_SYMBOL(in6_pton);
>>
>> +/**
>> + * inet_pton_with_scope - convert an IPv4/IPv6 and port to socket address
>> + * @net: net namespace (used for scope handling)
>> + * @af: address family, AF_INET, AF_INET6 or AF_UNSPEC for either
>> + * @src: the start of the address string
>> + * @port: the start of the port string (or NULL for none)
>> + * @addr: output socket address
>> + *
>> + * Return zero on success, return errno when any error occurs.
>> + */
>> +int inet_pton_with_scope(struct net *net, __kernel_sa_family_t af,
>> +		const char *src, const char *port, struct sockaddr_storage *addr)
>> +{
>> +	struct sockaddr_in *addr4;
>> +	struct sockaddr_in6 *addr6;
>> +	const char *scope_delim;
>> +	bool unspec = false;
>> +	int srclen = strlen(src);
>> +	u16 port_num;
>> +
>> +	if (port) {
>> +		if (kstrtou16(port, 0, &port_num)) {
>> +			pr_err("failed port_num %s\n", port);
>> +			return -EINVAL;
>> +		}
>> +	} else {
>> +		port_num = 0;
>> +	}
>> +
>> +	switch (af) {
>> +	case AF_UNSPEC:
>> +		unspec = true;
>> +		/* FALLTHRU */
>> +	case AF_INET:
>> +		if (srclen <= INET_ADDRSTRLEN) {
>> +			addr4 = (struct sockaddr_in *)addr;
>> +			if (in4_pton(src, srclen, (u8 *) &addr4->sin_addr.s_addr,
>> +				     '\n', NULL) > 0) {
>> +				addr4->sin_family = AF_INET;
>> +				addr4->sin_port = htons(port_num);
>> +				return 0;
>> +			}
>> +			pr_err("failed in4_pton %s\n", src);
>> +		}
>
> I would probably factor this and the IPv6 equivalent below into helpers
> to keep the code a little more self-contained so that we could avoid the
> fallthrough magic.

I can factor out ipv4/ipv6 to helpers, but still I need to try either
ipv4, ipv6, or both for unspec.

I can maybe do something like:

if (af == AF_INET || af == AF_UNSPEC) {
	ret = inet4_pton();
	if (!ret)
		return 0;
	else if (af != AF_UNSPEC)
		return ret;
}

if (af == AF_INET6 || af == AF_UNSPEC) {
	ret = inet6_pton();
	if (!ret)
		return 0;
	else if (af != AF_UNSPEC)
		return ret;
}

return -EINVAL;

better?