resolv: add IPv6 support to inet_net_pton()

  Dear all,

On Thu, Dec 22, 2022 at 06:54:58PM +0100, Job Snijders wrote:
> This changeset adds support to inet_net_pton() to convert IPv6 network
> numbers (IPv6 prefixes with CIDR notation) from presentation format to
> network format.
> 
> The starting point of this changeset was OpenBSD's
> libc/net/inet_net_pton.c (r1.13) implementation of inet_net_pton_ipv6().
> https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libc/net/inet_net_pton.c?annotate=1.13
> The OpenBSD implementation was adapted to glibc as following:
> 
> 1) Use strncpy() instead of strlcpy()
> 2) Use strtol() instead of strtonum()
> 3) Updated comments

I'm resending the patch (no changes, other than a/ and b/ are now
prefixed to the referenced paths), to hopefully trigger the build robot.

Kind regards,

Job

Signed-off: Job Snijders <job@fastly.com>
---
 resolv/inet_net_pton.c | 76 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 72 insertions(+), 4 deletions(-)
  

Hi all,

I hope you don't mind me drawing some attention to this patch: I'd love
for this to be merged! :-)

Kind regards,

Job

On Tue, Jan 17, 2023 at 11:56:03AM +0100, Job Snijders wrote:
> Dear all,
> 
> On Thu, Dec 22, 2022 at 06:54:58PM +0100, Job Snijders wrote:
> > This changeset adds support to inet_net_pton() to convert IPv6 network
> > numbers (IPv6 prefixes with CIDR notation) from presentation format to
> > network format.
> > 
> > The starting point of this changeset was OpenBSD's
> > libc/net/inet_net_pton.c (r1.13) implementation of inet_net_pton_ipv6().
> > https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libc/net/inet_net_pton.c?annotate=1.13
> > The OpenBSD implementation was adapted to glibc as following:
> > 
> > 1) Use strncpy() instead of strlcpy()
> > 2) Use strtol() instead of strtonum()
> > 3) Updated comments
> 
> I'm resending the patch (no changes, other than a/ and b/ are now
> prefixed to the referenced paths), to hopefully trigger the build robot.
> 
> Kind regards,
> 
> Job
> 
> Signed-off: Job Snijders <job@fastly.com>
> ---
>  resolv/inet_net_pton.c | 76 +++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 72 insertions(+), 4 deletions(-)
> 
> diff --git a/resolv/inet_net_pton.c b/resolv/inet_net_pton.c
> index aab9b7b582..163e76e1a5 100644
> --- a/resolv/inet_net_pton.c
> +++ b/resolv/inet_net_pton.c
> @@ -1,4 +1,6 @@
>  /*
> + * Copyright (c) 2022 Job Snijders <job@fastly.com>
> + * Copyright (c) 2012 by Gilles Chehade <gilles@openbsd.org>
>   * Copyright (c) 1996,1999 by Internet Software Consortium.
>   *
>   * Permission to use, copy, modify, and distribute this software for any
> @@ -35,13 +37,16 @@
>  
>  static int	inet_net_pton_ipv4 (const char *src, u_char *dst,
>  				    size_t size) __THROW;
> +static int	inet_net_pton_ipv6 (const char *src, u_char *dst,
> +				    size_t size) __THROW;
>  
>  /*
> - * static int
> + * int
>   * inet_net_pton(af, src, dst, size)
> - *	convert network number from presentation to network format.
> - *	accepts hex octets, hex strings, decimal octets, and /CIDR.
> - *	"size" is in bytes and describes "dst".
> + *	Convert network number from presentation format to network format.
> + *	If "af" is set to AF_INET, accept various formats like hex octets,
> + *	hex strings, or decimal octets. If "af" is set to AF_INET6, accept
> + *	IPv6 addresses. "size" is in bytes and describes "dst".
>   * return:
>   *	number of bits, either imputed classfully or specified with /CIDR,
>   *	or -1 if some failure occurred (check errno).  ENOENT means it was
> @@ -55,6 +60,8 @@ inet_net_pton (int af, const char *src, void *dst, size_t size)
>  	switch (af) {
>  	case AF_INET:
>  		return (inet_net_pton_ipv4(src, dst, size));
> +	case AF_INET6:
> +		return (inet_net_pton_ipv6(src, dst, size));
>  	default:
>  		__set_errno (EAFNOSUPPORT);
>  		return (-1);
> @@ -196,3 +203,64 @@ inet_net_pton_ipv4 (const char *src, u_char *dst, size_t size)
>  	__set_errno (EMSGSIZE);
>  	return (-1);
>  }
> +
> +
> +/*
> + * Convert an IPv6 prefix from presentation format to network format.
> + * Return the number of bits specified, or -1 as error (check errno).
> + */
> +static int
> +inet_net_pton_ipv6 (const char *src, u_char *dst, size_t size)
> +{
> +	struct in6_addr	 in6;
> +	int		 bits;
> +	long		 lbits;
> +	size_t		 bytes;
> +	char		 buf[INET6_ADDRSTRLEN + sizeof("/128")];
> +	char		*ep, *sep;
> +
> +	strncpy(buf, src, sizeof(buf) - 1);
> +	buf[sizeof(buf) - 1] = '\0';
> +
> +	sep = strchr(buf, '/');
> +	if (sep != NULL)
> +		*sep++ = '\0';
> +
> +	if (inet_pton(AF_INET6, buf, &in6) != 1) {
> +		__set_errno (ENOENT);
> +		return (-1);
> +	}
> +
> +	if (sep == NULL) {
> +		bits = 128;
> +		goto out;
> +	}
> +
> +	if (sep[0] == '\0' || !isascii(sep[0]) || !isdigit(sep[0])) {
> +		__set_errno (ENOENT);
> +		return (-1);
> +	}
> +
> +	errno = 0;
> +	lbits = strtol(sep, &ep, 10);
> +	if (sep[0] == '\0' || *ep != '\0') {
> +		__set_errno (ENOENT);
> +		return (-1);
> +	}
> +	if ((errno == ERANGE && (lbits == LONG_MAX || lbits == LONG_MIN))
> +	    || (lbits > 128 || lbits < 0)) {
> +		__set_errno (EMSGSIZE);
> +		return (-1);
> +	}
> +	bits = lbits;
> +
> + out:
> +	bytes = (bits + 7) / 8;
> +	if (bytes > size) {
> +		__set_errno (EMSGSIZE);
> +		return (-1);
> +	}
> +
> +	memcpy(dst, &in6.s6_addr, bytes);
> +	return (bits);
> +}