xshared: Share make_delete_mask() between ip{,6}tables

Function bodies were mostly identical, the only difference being the use
of struct ipt_entry or ip6t_entry for size calculation. Pass this value
via parameter to make them fully identical.

Signed-off-by: Phil Sutter <phil@nwl.cc>

4 files changed, 42 insertions, 72 deletions

diff --git a/iptables/ip6tables.c b/iptables/ip6tables.c
index 75984cc1..ae267035 100644
--- a/iptables/ip6tables.c
+++ b/iptables/ip6tables.c
@@ -277,40 +277,6 @@ insert_entry(const xt_chainlabel chain,
 	return ret;
 }
 
-static unsigned char *
-make_delete_mask(const struct xtables_rule_match *matches,
-		 const struct xtables_target *target)
-{
-	/* Establish mask for comparison */
-	unsigned int size;
-	const struct xtables_rule_match *matchp;
-	unsigned char *mask, *mptr;
-
-	size = sizeof(struct ip6t_entry);
-	for (matchp = matches; matchp; matchp = matchp->next)
-		size += XT_ALIGN(sizeof(struct xt_entry_match)) + matchp->match->size;
-
-	mask = xtables_calloc(1, size
-			 + XT_ALIGN(sizeof(struct xt_entry_target))
-			 + target->size);
-
-	memset(mask, 0xFF, sizeof(struct ip6t_entry));
-	mptr = mask + sizeof(struct ip6t_entry);
-
-	for (matchp = matches; matchp; matchp = matchp->next) {
-		memset(mptr, 0xFF,
-		       XT_ALIGN(sizeof(struct xt_entry_match))
-		       + matchp->match->userspacesize);
-		mptr += XT_ALIGN(sizeof(struct xt_entry_match)) + matchp->match->size;
-	}
-
-	memset(mptr, 0xFF,
-	       XT_ALIGN(sizeof(struct xt_entry_target))
-	       + target->userspacesize);
-
-	return mask;
-}
-
 static int
 delete_entry(const xt_chainlabel chain,
 	     struct ip6t_entry *fw,
@@ -329,7 +295,7 @@ delete_entry(const xt_chainlabel chain,
 	int ret = 1;
 	unsigned char *mask;
 
-	mask = make_delete_mask(matches, target);
+	mask = make_delete_mask(matches, target, sizeof(*fw));
 	for (i = 0; i < nsaddrs; i++) {
 		fw->ipv6.src = saddrs[i];
 		fw->ipv6.smsk = smasks[i];
@@ -359,7 +325,7 @@ check_entry(const xt_chainlabel chain, struct ip6t_entry *fw,
 	int ret = 1;
 	unsigned char *mask;
 
-	mask = make_delete_mask(matches, target);
+	mask = make_delete_mask(matches, target, sizeof(fw));
 	for (i = 0; i < nsaddrs; i++) {
 		fw->ipv6.src = saddrs[i];
 		fw->ipv6.smsk = smasks[i];
diff --git a/iptables/iptables.c b/iptables/iptables.c
index e5207ba1..591ec178 100644
--- a/iptables/iptables.c
+++ b/iptables/iptables.c
@@ -276,40 +276,6 @@ insert_entry(const xt_chainlabel chain,
 	return ret;
 }
 
-static unsigned char *
-make_delete_mask(const struct xtables_rule_match *matches,
-		 const struct xtables_target *target)
-{
-	/* Establish mask for comparison */
-	unsigned int size;
-	const struct xtables_rule_match *matchp;
-	unsigned char *mask, *mptr;
-
-	size = sizeof(struct ipt_entry);
-	for (matchp = matches; matchp; matchp = matchp->next)
-		size += XT_ALIGN(sizeof(struct xt_entry_match)) + matchp->match->size;
-
-	mask = xtables_calloc(1, size
-			 + XT_ALIGN(sizeof(struct xt_entry_target))
-			 + target->size);
-
-	memset(mask, 0xFF, sizeof(struct ipt_entry));
-	mptr = mask + sizeof(struct ipt_entry);
-
-	for (matchp = matches; matchp; matchp = matchp->next) {
-		memset(mptr, 0xFF,
-		       XT_ALIGN(sizeof(struct xt_entry_match))
-		       + matchp->match->userspacesize);
-		mptr += XT_ALIGN(sizeof(struct xt_entry_match)) + matchp->match->size;
-	}
-
-	memset(mptr, 0xFF,
-	       XT_ALIGN(sizeof(struct xt_entry_target))
-	       + target->userspacesize);
-
-	return mask;
-}
-
 static int
 delete_entry(const xt_chainlabel chain,
 	     struct ipt_entry *fw,
@@ -328,7 +294,7 @@ delete_entry(const xt_chainlabel chain,
 	int ret = 1;
 	unsigned char *mask;
 
-	mask = make_delete_mask(matches, target);
+	mask = make_delete_mask(matches, target, sizeof(*fw));
 	for (i = 0; i < nsaddrs; i++) {
 		fw->ip.src.s_addr = saddrs[i].s_addr;
 		fw->ip.smsk.s_addr = smasks[i].s_addr;
@@ -358,7 +324,7 @@ check_entry(const xt_chainlabel chain, struct ipt_entry *fw,
 	int ret = 1;
 	unsigned char *mask;
 
-	mask = make_delete_mask(matches, target);
+	mask = make_delete_mask(matches, target, sizeof(*fw));
 	for (i = 0; i < nsaddrs; i++) {
 		fw->ip.src.s_addr = saddrs[i].s_addr;
 		fw->ip.smsk.s_addr = smasks[i].s_addr;
diff --git a/iptables/xshared.c b/iptables/xshared.c
index 69515789..0beacee6 100644
--- a/iptables/xshared.c
+++ b/iptables/xshared.c
@@ -2000,3 +2000,37 @@ void ipv6_post_parse(int command, struct iptables_command_state *cs,
 			      "! not allowed with multiple"
 			      " source or destination IP addresses");
 }
+
+unsigned char *
+make_delete_mask(const struct xtables_rule_match *matches,
+		 const struct xtables_target *target,
+		 size_t entry_size)
+{
+	/* Establish mask for comparison */
+	unsigned int size = entry_size;
+	const struct xtables_rule_match *matchp;
+	unsigned char *mask, *mptr;
+
+	for (matchp = matches; matchp; matchp = matchp->next)
+		size += XT_ALIGN(sizeof(struct xt_entry_match)) + matchp->match->size;
+
+	mask = xtables_calloc(1, size
+			 + XT_ALIGN(sizeof(struct xt_entry_target))
+			 + target->size);
+
+	memset(mask, 0xFF, entry_size);
+	mptr = mask + entry_size;
+
+	for (matchp = matches; matchp; matchp = matchp->next) {
+		memset(mptr, 0xFF,
+		       XT_ALIGN(sizeof(struct xt_entry_match))
+		       + matchp->match->userspacesize);
+		mptr += XT_ALIGN(sizeof(struct xt_entry_match)) + matchp->match->size;
+	}
+
+	memset(mptr, 0xFF,
+	       XT_ALIGN(sizeof(struct xt_entry_target))
+	       + target->userspacesize);
+
+	return mask;
+}
diff --git a/iptables/xshared.h b/iptables/xshared.h
index f43c28f5..bfae4b4e 100644
--- a/iptables/xshared.h
+++ b/iptables/xshared.h
@@ -293,4 +293,8 @@ void ipv6_post_parse(int command, struct iptables_command_state *cs,
 extern char *arp_opcodes[];
 #define ARP_NUMOPCODES 9
 
+unsigned char *make_delete_mask(const struct xtables_rule_match *matches,
+				const struct xtables_target *target,
+				size_t entry_size);
+
 #endif /* IPTABLES_XSHARED_H */