Re: [PATCH] resolv: add IPv6 support to inet_net_pton()

[Job Snijders <job@fastly.com>]

Dear all,

Are there any other comments, or can this be considered for merging? :-)

Kind regards,

Job

On Mon, Mar 25, 2024 at 09:04:52AM +0000, Job Snijders wrote:
> Dear Zack,
> 
> On Fri, Mar 22, 2024 at 10:24:35AM -0400, Zack Weinberg wrote:
> > Please change that to "ep == sep", even if you make no other changes.
> > 
> > Anyway, I would have written this as
> > 
> >     lbits = strtol(sep, &ep, 10);
> >     if (ep == sep || *ep != '\0') {
> >         __set_errno(ENOENT);
> >         return -1;
> >     }
> >     if (lbits < 0 || lbits > 128) {
> >         __set_errno(EMSGSIZE);
> >         return -1;
> >     }
> > 
> > and I do think this is an improvement over what you had, largely
> > because it eliminates the need to save and restore the original value
> > of errno.
> 
> Thank you for your response, I've adjusted the proposal according to
> your notes.
> 
> Kind regards,
> 
> Job
> 
> Signed-off: Job Snijders <job@fastly.com>
> ---
>  resolv/inet_net_pton.c | 69 +++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 65 insertions(+), 4 deletions(-)
> 
> diff --git a/resolv/inet_net_pton.c b/resolv/inet_net_pton.c
> index 63a47b7394..93753cb37f 100644
> --- a/resolv/inet_net_pton.c
> +++ b/resolv/inet_net_pton.c
> @@ -1,4 +1,6 @@
>  /*
> + * Copyright (c) 2024 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
> @@ -19,6 +21,7 @@
>  #include <sys/socket.h>
>  #include <netinet/in.h>
>  #include <arpa/inet.h>
> +#include <resolv/resolv-internal.h>
>  
>  #include <assert.h>
>  #include <ctype.h>
> @@ -35,13 +38,16 @@
>  
>  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 +61,8 @@ 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 +204,56 @@ 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		*ep, *sep;
> +
> +	sep = strchr(src, '/');
> +
> +	if (__inet_pton_length(AF_INET6, src, sep ? sep - src : strlen(src),
> +	    &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);
> +	}
> +
> +	lbits = strtol(sep, &ep, 10);
> +	if (ep == sep || *ep != '\0') {
> +		__set_errno (ENOENT);
> +		return (-1);
> +	}
> +	if (lbits < 0 || lbits > 128) {
> +		__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);
> +}