Re: [PATCH 04/22] treewide: Use struct assignment instead of memcpy() for IP addresses

On Sun, Aug 18, 2024 at 05:45:03PM +0200, Stefano Brivio wrote:
...
  On Fri, 16 Aug 2024 15:39:45 +1000
 David Gibson <david(a)gibson.dropbear.id.au> wrote:
 
  We rely on C11 already, so we can use clearer and
more type-checkable
 struct assignment instead of mempcy() for copying IP addresses around.
 
 This exposes some "pointer could be const" warnings from cppcheck, so
 address those too.
 
 Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
 ---
  conf.c   | 12 ++++++------
  dhcpv6.c | 10 ++++++----
  2 files changed, 12 insertions(+), 10 deletions(-)
 
 diff --git a/conf.c b/conf.c
 index 750fdc86..9b05afeb 100644
 --- a/conf.c
 +++ b/conf.c
 @@ -389,14 +389,14 @@ static void add_dns6(struct ctx *c,
  	/* Guest or container can only access local addresses via redirect */
  	if (IN6_IS_ADDR_LOOPBACK(addr)) {
  		if (!c->no_map_gw) {
 -			memcpy(*conf, &c->ip6.gw, sizeof(**conf));
 +			**conf = c->ip6.gw;
  			(*conf)++;
  
  			if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_match))
 -				memcpy(&c->ip6.dns_match, addr, sizeof(*addr));
 +				c->ip6.dns_match = *addr;
  		}
  	} else {
 -		memcpy(*conf, addr, sizeof(**conf));
 +		**conf = *addr;
  		(*conf)++;
  	}
  
 @@ -632,7 +632,7 @@ static unsigned int conf_ip4(unsigned int ifi,
  			ip4->prefix_len = 32;
  	}
  
 -	memcpy(&ip4->addr_seen, &ip4->addr, sizeof(ip4->addr_seen));
 +	ip4->addr_seen = ip4->addr;
  
  	if (MAC_IS_ZERO(mac)) {
  		int rc = nl_link_get_mac(nl_sock, ifi, mac);
 @@ -693,8 +693,8 @@ static unsigned int conf_ip6(unsigned int ifi,
  		return 0;
  	}
  
 -	memcpy(&ip6->addr_seen, &ip6->addr, sizeof(ip6->addr));
 -	memcpy(&ip6->addr_ll_seen, &ip6->addr_ll, sizeof(ip6->addr_ll));
 +	ip6->addr_seen = ip6->addr;
 +	ip6->addr_ll_seen = ip6->addr_ll;
  
  	if (MAC_IS_ZERO(mac)) {
  		rc = nl_link_get_mac(nl_sock, ifi, mac);
 diff --git a/dhcpv6.c b/dhcpv6.c
 index bbed41dc..87b3c3eb 100644
 --- a/dhcpv6.c
 +++ b/dhcpv6.c
 @@ -298,7 +298,8 @@ static struct opt_hdr *dhcpv6_ia_notonlink(const struct pool *p,
  {
  	char buf[INET6_ADDRSTRLEN];
  	struct in6_addr req_addr;
 -	struct opt_hdr *ia, *h;
 +	const struct opt_hdr *h;
 +	struct opt_hdr *ia;
  	size_t offset;
  	int ia_type;
  
 @@ -312,12 +313,13 @@ ia_ta:
  		offset += sizeof(struct opt_ia_na);
  
  		while ((h = dhcpv6_opt(p, &offset, OPT_IAAADR))) {
 -			struct opt_ia_addr *opt_addr = (struct opt_ia_addr *)h;
 +			const struct opt_ia_addr *opt_addr
 +				= (const struct opt_ia_addr *)h; 
 
 Nit: the assignment could go on its own line, then? 
Good point, done.

...
 
   			if
(ntohs(h->l) != OPT_VSIZE(ia_addr))
  				return NULL;
  
 -			memcpy(&req_addr, &opt_addr->addr, sizeof(req_addr));
 +			req_addr = opt_addr->addr;
  			if (!IN6_ARE_ADDR_EQUAL(la, &req_addr)) {
  				info("DHCPv6: requested address %s not on link",
  				     inet_ntop(AF_INET6, &req_addr,
 @@ -363,7 +365,7 @@ static size_t dhcpv6_dns_fill(const struct ctx *c, char *buf, int
offset)
  			srv->hdr.l = 0;
  		}
  
 -		memcpy(&srv->addr[i], &c->ip6.dns[i], sizeof(srv->addr[i]));
 +		srv->addr[i] = c->ip6.dns[i];
  		srv->hdr.l += sizeof(srv->addr[i]);
  		offset += sizeof(srv->addr[i]);
  	} 
 
 I only reviewed up to this patch so far.
  
-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson