RE: [PATCH 02/12] net: add function to pretty print IPv4

["Morten Brørup" <mb@smartsharesystems.com>]

> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Wednesday, 15 December 2021 04.21
> 
> On Wed, 15 Dec 2021 01:06:14 +0000
> "Ananyev, Konstantin" <konstantin.ananyev@intel.com> wrote:
> 
> > > -----Original Message-----
> > > From: Morten Brørup <mb@smartsharesystems.com>
> > > Sent: Tuesday, December 14, 2021 5:31 PM
> > > To: Randles, Ronan <ronan.randles@intel.com>; dev@dpdk.org
> > > Cc: Van Haaren, Harry <harry.van.haaren@intel.com>
> > > Subject: RE: [PATCH 02/12] net: add function to pretty print IPv4
> > >
> > > > From: Ronan Randles [mailto:ronan.randles@intel.com]
> > > > Sent: Tuesday, 14 December 2021 15.13
> > > >
> > > > This function accepts an uint32_t representation of an IP address
> and
> > > > produces a string representation stored in a char * buffer.
> Realavent
> > > > unit tests also included.
> > > >
> > > > Signed-off-by: Ronan Randles <ronan.randles@intel.com>
> > >
> > > [snip]
> > >
> > > > diff --git a/lib/net/rte_ip.h b/lib/net/rte_ip.h
> > > > index 188054fda4..e46f0b41ba 100644
> > > > --- a/lib/net/rte_ip.h
> > > > +++ b/lib/net/rte_ip.h
> > > > @@ -444,6 +444,26 @@ __rte_experimental
> > > >  int32_t
> > > >  rte_ip_parse_addr(const char *src_ip, uint32_t *output_addr);
> > > >
> > > > +
> > > > +/**
> > > > + * Print IP address from 32 bit int into char * buffer.
> > > > + *
> > > > + * @param ip_addr
> > > > + *   ip address to be printed.
> > > > + * @param buffer
> > > > + *   The buffer the string will be saved into.
> > > > + * @param buffer_size
> > > > + *   size of buffer to be used.
> > > > + *
> > > > + * @retval 0
> > > > + *   Success.
> > > > + * @retval -1
> > > > + *   Failure due to invalid input arguments.
> > > > + */
> > > > +__rte_experimental
> > > > +int32_t
> > > > +rte_ip_print_addr(uint32_t ip_addr, char *buffer, uint32_t
> > > > buffer_size);
> > > > +
> > >
> > > In continuation of my email reply about the IPv4 parse function...
> > >
> > > I have a few suggestions to the IPv4 print function too:
> > >
> > > The return value should be the number of characters written to the
> output string, and still -1 on error. With this modification, you could
> > > use the return type ssize_t instead of int32_t.
> > >
> > > Furthermore, I would prefer having the parameters in the same order
> as snprintf(): char *str, size_t size, const uint32_t ip_addr. Please
> > > also notice the suggested changed type for the size, and the const
> added to the ip_addr.
> > >
> > Honestly, I don't understand why we need to introduce such functions
> > inside DPDK at all.
> > What's wrong with existing standard ones: inet_ntop() and
> inet_pton()?
> 
> Agreed, I see no added value in reinventing here

I think that DPDK functions for converting all sorts of types to/from strings would be useful; not only IP addresses, but also MAC addresses, TCP/UDP port numbers and VLAN IDs.

If you don't like IP address string conversion functions in the net library, DPDK could have a string conversions library. That library could expose a multitude of APIs for the same purpose, so the application can use the API that best fits each application use.