routing: Add command line option to specify external IP address

We don't currently have a good way to determine our external IP
address so let's at least give people an option to manually specify
it.

daemon/lightningd.h

@@ -7,6 +7,7 @@
 #include <ccan/short_types/short_types.h>
 #include <ccan/timer/timer.h>
 #include <stdio.h>
+#include <wire/wire.h>
 
 /* Various adjustable things. */
 struct config {
@@ -58,6 +59,9 @@ struct config {
 
 	/* Whether to ignore database version. */
 	bool db_version_ignore;
+
+	/* IPv4 or IPv6 address to announce to the network */
+	struct ipaddr ipaddr;
 };
 
 /* Here's where the global variables hide! */

daemon/options.c

@@ -7,6 +7,7 @@
 #include "daemon/options.h"
 #include "daemon/routing.h"
 #include "version.h"
+#include <arpa/inet.h>
 #include <ccan/err/err.h>
 #include <ccan/opt/opt.h>
 #include <ccan/short_types/short_types.h>
@@ -20,6 +21,7 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
+#include <wire/wire.h>
 
 /* Tal wrappers for opt. */
 static void *opt_allocfn(size_t size)
@@ -109,6 +111,26 @@ static char *opt_set_s32(const char *arg, s32 *u)
 	return NULL;
 }
 
+static char *opt_set_ipaddr(const char *arg, struct ipaddr *addr)
+{
+	struct in6_addr v6;
+	struct in_addr v4;
+	char *err = NULL;
+	memset(&addr->addr, 0, sizeof(addr->addr));
+	if (inet_pton(AF_INET, arg, &v4) == 1) {
+		addr->type = ADDR_TYPE_IPV4;
+		addr->addrlen = 4;
+		memcpy(&addr->addr, &v4, addr->addrlen);
+	} else if (inet_pton(AF_INET6, arg, &v6) == 1) {
+		addr->type = ADDR_TYPE_IPV6;
+		addr->addrlen = 16;
+		memcpy(&addr->addr, &v6, addr->addrlen);
+	} else {
+		err = tal_fmt(NULL, "Unable to parse IP address '%s'", arg);
+	}
+	return err;
+}
+
 static void opt_show_u64(char buf[OPT_SHOW_LEN], const u64 *u)
 {
 	snprintf(buf, OPT_SHOW_LEN, "%"PRIu64, *u);
@@ -205,6 +227,10 @@ static void config_register_opts(struct lightningd_state *dstate)
 	opt_register_noarg("--ignore-dbversion", opt_set_bool,
 			   &dstate->config.db_version_ignore,
 			   "Continue despite invalid database version (DANGEROUS!)");
+
+	opt_register_arg("--ipaddr", opt_set_ipaddr, NULL,
+			   &dstate->config.ipaddr,
+			   "Set the IP address (v4 or v6) to announce to the network for incoming connections");
 }
 
 static void dev_register_opts(struct lightningd_state *dstate)
@@ -273,6 +299,9 @@ static const struct config testnet_config = {
 
 	/* Don't ignore database version */
 	.db_version_ignore = false,
+
+	/* Do not advertise any IP */
+	.ipaddr.type = 0,
 };
 
 /* aka. "Dude, where's my coins?" */
@@ -334,6 +363,9 @@ static const struct config mainnet_config = {
 
 	/* Don't ignore database version */
 	.db_version_ignore = false,
+
+	/* Do not advertise any IP */
+	.ipaddr.type = 0,
 };
 
 static void check_config(struct lightningd_state *dstate)
@@ -488,6 +520,7 @@ bool handle_opts(struct lightningd_state *dstate, int argc, char *argv[])
 	/* Now look for config file */
 	opt_parse_from_config(dstate);
 
+	dstate->config.ipaddr.port = dstate->portnum;
 	opt_parse(&argc, argv, opt_log_stderr_exit);
 	if (argc != 1)
 		errx(1, "no arguments accepted");

wire/fromwire.c

@@ -165,9 +165,27 @@ void fromwire_preimage(const u8 **cursor, size_t *max, struct preimage *preimage
 	fromwire(cursor, max, preimage, sizeof(*preimage));
 }
 
-void fromwire_ipv6(const u8 **cursor, size_t *max, struct ipv6 *ipv6)
+void fromwire_ipaddr(const u8 **cursor, size_t *max, struct ipaddr *addr)
 {
-	fromwire(cursor, max, ipv6, sizeof(*ipv6));
+	/* Skip any eventual padding */
+	while (**cursor == 0) {
+		*cursor += 1;
+	}
+
+	addr->type = **cursor;
+	switch (addr->type) {
+	case 1:
+		addr->addrlen = 4;
+		break;
+	case 2:
+		addr->addrlen = 16;
+		break;
+	default:
+		fail_pull(cursor, max);
+		return;
+	}
+	fromwire(cursor, max, addr->addr, addr->addrlen);
+	addr->port = fromwire_u16(cursor, max);
 }
 
 void fromwire_u8_array(const u8 **cursor, size_t *max, u8 *arr, size_t num)

wire/towire.c

@@ -109,9 +109,11 @@ void towire_preimage(u8 **pptr, const struct preimage *preimage)
 	towire(pptr, preimage, sizeof(*preimage));
 }
 
-void towire_ipv6(u8 **pptr, const struct ipv6 *ipv6)
+void towire_ipaddr(u8 **pptr, const struct ipaddr *addr)
 {
-	towire(pptr, ipv6, sizeof(*ipv6));
+	towire_u8(pptr, addr->type);
+	towire(pptr, addr->addr, addr->addrlen);
+	towire_u16(pptr, addr->port);
 }
 
 void towire_u8_array(u8 **pptr, const u8 *arr, size_t num)

wire/wire.h

@@ -17,9 +17,26 @@ struct short_channel_id {
 struct channel_id {
 	u8 id[32];
 };
-struct ipv6 {
+
+/* Address types as defined in the lightning specification. Does not
+ * match AF_INET and AF_INET6 so we just define our
+ * own. ADDR_TYPE_PADDING is also used to signal in the config whether
+ * an address is defined at all. */
+enum wire_addr_type {
+	ADDR_TYPE_PADDING = 0,
+	ADDR_TYPE_IPV4 = 1,
+	ADDR_TYPE_IPV6 = 2,
+};
+
+/* FIXME(cdecker) Extend this once we have defined how TOR addresses
+ * should look like */
+struct ipaddr {
+	enum wire_addr_type type;
+	u8 addrlen;
 	u8 addr[16];
+	u16 port;
 };
+
 struct preimage;
 
 void derive_channel_id(struct channel_id *channel_id,
@@ -40,7 +57,7 @@ void towire_short_channel_id(u8 **pptr,
 void towire_sha256(u8 **pptr, const struct sha256 *sha256);
 void towire_sha256_double(u8 **pptr, const struct sha256_double *sha256d);
 void towire_preimage(u8 **pptr, const struct preimage *preimage);
-void towire_ipv6(u8 **pptr, const struct ipv6 *ipv6);
+void towire_ipaddr(u8 **pptr, const struct ipaddr *addr);
 void towire_u8(u8 **pptr, u8 v);
 void towire_u16(u8 **pptr, u16 v);
 void towire_u32(u8 **pptr, u32 v);
@@ -69,7 +86,7 @@ void fromwire_sha256(const u8 **cursor, size_t *max, struct sha256 *sha256);
 void fromwire_sha256_double(const u8 **cursor, size_t *max,
 			    struct sha256_double *sha256d);
 void fromwire_preimage(const u8 **cursor, size_t *max, struct preimage *preimage);
-void fromwire_ipv6(const u8 **cursor, size_t *max, struct ipv6 *ipv6);
+void fromwire_ipaddr(const u8 **cursor, size_t *max, struct ipaddr *addr);
 void fromwire_pad(const u8 **cursor, size_t *max, size_t num);
 
 void fromwire_u8_array(const u8 **cursor, size_t *max, u8 *arr, size_t num);