From 28b3be64cdeb318647587bc3a7cbacbac087a84f Mon Sep 17 00:00:00 2001
From: llccd <lu_5030683@outlook.com>
Date: Sun, 20 Oct 2019 11:42:54 +0800
Subject: Add --to-source option

---
 libipt_FULLCONENAT.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 xt_FULLCONENAT.c     | 12 ++++++++---
 2 files changed, 70 insertions(+), 3 deletions(-)

diff --git a/libipt_FULLCONENAT.c b/libipt_FULLCONENAT.c
index 9965cd7..023dc91 100644
--- a/libipt_FULLCONENAT.c
+++ b/libipt_FULLCONENAT.c
@@ -16,12 +16,15 @@ enum {
 	O_TO_PORTS = 0,
 	O_RANDOM,
 	O_RANDOM_FULLY,
+	O_TO_SRC,
 };
 
 static void FULLCONENAT_help(void)
 {
 	printf(
 "FULLCONENAT target options:\n"
+" --to-source [<ipaddr>[-<ipaddr>]]\n"
+"				Address to map source to.\n"
 " --to-ports <port>[-<port>]\n"
 "				Port (range) to map to.\n"
 " --random\n"
@@ -34,9 +37,42 @@ static const struct xt_option_entry FULLCONENAT_opts[] = {
 	{.name = "to-ports", .id = O_TO_PORTS, .type = XTTYPE_STRING},
 	{.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE},
 	{.name = "random-fully", .id = O_RANDOM_FULLY, .type = XTTYPE_NONE},
+	{.name = "to-source", .id = O_TO_SRC, .type = XTTYPE_STRING},
 	XTOPT_TABLEEND,
 };
 
+static void parse_to(const char *orig_arg, struct nf_nat_ipv4_multi_range_compat *mr)
+{
+	char *arg, *dash, *error;
+	const struct in_addr *ip;
+
+	arg = strdup(orig_arg);
+	if (arg == NULL)
+		xtables_error(RESOURCE_PROBLEM, "strdup");
+
+	mr->range[0].flags |= NF_NAT_RANGE_MAP_IPS;
+	dash = strchr(arg, '-');
+
+	if (dash)
+		*dash = '\0';
+
+	ip = xtables_numeric_to_ipaddr(arg);
+	if (!ip)
+		xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
+			   arg);
+	mr->range[0].min_ip = ip->s_addr;
+	if (dash) {
+		ip = xtables_numeric_to_ipaddr(dash+1);
+		if (!ip)
+			xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
+				   dash+1);
+		mr->range[0].max_ip = ip->s_addr;
+	} else
+		mr->range[0].max_ip = mr->range[0].min_ip;
+
+	free(arg);
+}
+
 static void FULLCONENAT_init(struct xt_entry_target *t)
 {
 	struct nf_nat_ipv4_multi_range_compat *mr = (struct nf_nat_ipv4_multi_range_compat *)t->data;
@@ -102,6 +138,9 @@ static void FULLCONENAT_parse(struct xt_option_call *cb)
 				   "Need TCP, UDP, SCTP or DCCP with port specification");
 		parse_ports(cb->arg, mr);
 		break;
+	case O_TO_SRC:
+		parse_to(cb->arg, mr);
+		break;
 	case O_RANDOM:
 		mr->range[0].flags |=  NF_NAT_RANGE_PROTO_RANDOM;
 		break;
@@ -118,6 +157,17 @@ FULLCONENAT_print(const void *ip, const struct xt_entry_target *target,
 	const struct nf_nat_ipv4_multi_range_compat *mr = (const void *)target->data;
 	const struct nf_nat_ipv4_range *r = &mr->range[0];
 
+	if (r->flags & NF_NAT_RANGE_MAP_IPS) {
+		struct in_addr a;
+
+		a.s_addr = r->min_ip;
+		printf(" to:%s", xtables_ipaddr_to_numeric(&a));
+		if (r->max_ip != r->min_ip) {
+			a.s_addr = r->max_ip;
+			printf("-%s", xtables_ipaddr_to_numeric(&a));
+		}
+	}
+
 	if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
 		printf(" masq ports: ");
 		printf("%hu", ntohs(r->min.tcp.port));
@@ -138,6 +188,17 @@ FULLCONENAT_save(const void *ip, const struct xt_entry_target *target)
 	const struct nf_nat_ipv4_multi_range_compat *mr = (const void *)target->data;
 	const struct nf_nat_ipv4_range *r = &mr->range[0];
 
+	if (r->flags & NF_NAT_RANGE_MAP_IPS) {
+		struct in_addr a;
+
+		a.s_addr = r->min_ip;
+		printf(" --to-source %s", xtables_ipaddr_to_numeric(&a));
+		if (r->max_ip != r->min_ip) {
+			a.s_addr = r->max_ip;
+			printf("-%s", xtables_ipaddr_to_numeric(&a));
+		}
+	}
+
 	if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
 		printf(" --to-ports %hu", ntohs(r->min.tcp.port));
 		if (r->max.tcp.port != r->min.tcp.port)
diff --git a/xt_FULLCONENAT.c b/xt_FULLCONENAT.c
index 9e52eba..f209336 100644
--- a/xt_FULLCONENAT.c
+++ b/xt_FULLCONENAT.c
@@ -590,9 +590,15 @@ static unsigned int fullconenat_tg(struct sk_buff *skb, const struct xt_action_p
       }
     }
 
-    new_ip = get_device_ip(skb->dev);
-    newrange.min_addr.ip = new_ip;
-    newrange.max_addr.ip = new_ip;
+    if(mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
+      newrange.min_addr.ip = mr->range[0].min_ip;
+      newrange.max_addr.ip = mr->range[0].max_ip;
+    }
+    else {
+      new_ip = get_device_ip(skb->dev);
+      newrange.min_addr.ip = new_ip;
+      newrange.max_addr.ip = new_ip;
+    }
 
     /* do SNAT now */
     ret = nf_nat_setup_info(ct, &newrange, HOOK2MANIP(xt_hooknum(par)));
-- 
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