Pack DHCPv6 "on wire" structures

dhcpv6.c contains a number of structures which represent actual DHCPv6
packets as they appear on the wire, which will break if the structures
don't have exactly the in-memory layout we expect.

Therefore, we should mark these structures as ((packed)).  The contents of
them means this is unlikely to change the layout in practice - and since
it was working, presumably didn't on any arch we were testing on.  However
it's not impossible for the compiler on some arch to insert unexpected
padding in one of these structures, so we should be explicit.

clang-tidy warned about this since we were using memcmp() to compare some
of these structures, which it thought might not have a unique
representation.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 13 insertions, 13 deletions

diff --git a/dhcpv6.c b/dhcpv6.c
index fbae88d..8a1d4a6 100644
--- a/dhcpv6.c
+++ b/dhcpv6.c
@@ -62,7 +62,7 @@ struct opt_hdr {
 #define   STR_NOTONLINK		"Prefix not appropriate for link."
 
 	uint16_t l;
-};
+} __attribute__((packed));
 
 #if __BYTE_ORDER == __BIG_ENDIAN
 # define OPT_SIZE_CONV(x)	(x)
@@ -82,7 +82,7 @@ struct opt_hdr {
 struct opt_client_id {
 	struct opt_hdr hdr;
 	uint8_t duid[128];
-};
+} __attribute__((packed));
 
 /**
  * struct opt_server_id - DHCPv6 Server Identifier option
@@ -100,7 +100,7 @@ struct opt_server_id {
 	uint16_t duid_hw;
 	uint32_t duid_time;
 	uint8_t duid_lladdr[ETH_ALEN];
-};
+} __attribute__ ((packed));
 
 #if __BYTE_ORDER == __BIG_ENDIAN
 #define SERVER_ID {						\
@@ -128,7 +128,7 @@ struct opt_ia_na {
 	uint32_t iaid;
 	uint32_t t1;
 	uint32_t t2;
-};
+} __attribute__((packed));
 
 /**
  * struct opt_ia_ta - Identity Association for Temporary Addresses Option
@@ -138,7 +138,7 @@ struct opt_ia_na {
 struct opt_ia_ta {
 	struct opt_hdr hdr;
 	uint32_t iaid;
-};
+} __attribute__((packed));
 
 /**
  * struct opt_ia_addr - IA Address Option
@@ -152,7 +152,7 @@ struct opt_ia_addr {
 	struct in6_addr addr;
 	uint32_t pref_lifetime;
 	uint32_t valid_lifetime;
-};
+} __attribute__((packed));
 
 /**
  * struct opt_status_code - Status Code Option (used for NotOnLink error only)
@@ -164,7 +164,7 @@ struct opt_status_code {
 	struct opt_hdr hdr;
 	uint16_t code;
 	char status_msg[sizeof(STR_NOTONLINK) - 1];
-};
+} __attribute__((packed));
 
 /**
  * struct opt_dns_servers - DNS Recursive Name Server option (RFC 3646)
@@ -174,7 +174,7 @@ struct opt_status_code {
 struct opt_dns_servers {
 	struct opt_hdr hdr;
 	struct in6_addr addr[MAXNS];
-};
+} __attribute__((packed));
 
 /**
  * struct opt_dns_servers - Domain Search List option (RFC 3646)
@@ -184,7 +184,7 @@ struct opt_dns_servers {
 struct opt_dns_search {
 	struct opt_hdr hdr;
 	char list[MAXDNSRCH * NS_MAXDNAME];
-};
+} __attribute__((packed));
 
 /**
  * struct msg_hdr - DHCPv6 client/server message header
@@ -332,7 +332,7 @@ static struct opt_hdr *dhcpv6_ia_notonlink(const struct pool *p,
 					   struct in6_addr *la)
 {
 	char buf[INET6_ADDRSTRLEN];
-	struct in6_addr *req_addr;
+	struct in6_addr req_addr;
 	struct opt_hdr *ia, *h;
 	size_t offset;
 	int ia_type;
@@ -352,10 +352,10 @@ ia_ta:
 			if (ntohs(h->l) != OPT_VSIZE(ia_addr))
 				return NULL;
 
-			req_addr = &opt_addr->addr;
-			if (!IN6_ARE_ADDR_EQUAL(la, req_addr)) {
+			memcpy(&req_addr, &opt_addr->addr, sizeof(req_addr));
+			if (!IN6_ARE_ADDR_EQUAL(la, &req_addr)) {
 				info("DHCPv6: requested address %s not on link",
-				     inet_ntop(AF_INET6, req_addr,
+				     inet_ntop(AF_INET6, &req_addr,
 					       buf, sizeof(buf)));
 				return ia;
 			}