wireaddr: fix ipv6 formatting with ports in fmt_wireaddr

Correctly format ipv6 address with ports. This will also make it more compatible
with the new parse_wireaddr, which has been updated to parse ports. They are
inverses now.

Also add some tests that check this.

Signed-off-by: William Casarin <jb55@jb55.com>

common/test/run-ip_port_parsing.c

@@ -26,6 +26,7 @@ void towire_u8(u8 **pptr UNNEEDED, u8 v UNNEEDED)
 
 int main(void)
 {
+	struct wireaddr addr;
 	tal_t *ctx = tal_tmpctx(NULL);
 	char *ip;
 	u16 port;
@@ -35,6 +36,10 @@ int main(void)
 	assert(streq(ip, "::1"));
 	assert(port == 80);
 
+	assert(!parse_ip_port(ctx, "ip6-localhost", &ip, &port));
+	assert(streq(ip, "ip6-localhost"));
+	assert(port == 0);
+
 	assert(!parse_ip_port(ctx, "::1", &ip, &port));
 	assert(streq(ip, "::1"));
 	assert(port == 0);
@@ -47,6 +52,33 @@ int main(void)
 	assert(streq(ip, "192.168.2.255"));
 	assert(port == 0);
 
+	// unusual but possibly valid case
+	assert(!parse_ip_port(ctx, "[::1]", &ip, &port));
+	assert(streq(ip, "::1"));
+	assert(port == 0);
+
+	// service names not supported yet
+	assert(!parse_ip_port(ctx, "[::1]:http", &ip, &port));
+	assert(streq(ip, "::1"));
+	assert(port == 0);
+
+	// localhost hostnames for backward compat
+	parse_wireaddr("localhost", &addr, 200);
+	assert(addr.port == 200);
+
+	// string should win the port battle
+	parse_wireaddr("[::1]:9735", &addr, 500);
+	assert(addr.port == 9735);
+	ip = fmt_wireaddr(ctx, &addr);
+	assert(streq(ip, "[::1]:9735"));
+
+	// should use argument if we have no port in string
+	parse_wireaddr("2001:db8:85a3::8a2e:370:7334", &addr, 9777);
+	assert(addr.port == 9777);
+
+	ip = fmt_wireaddr(ctx, &addr);
+	assert(streq(ip, "[2001:db8:85a3::8a2e:370:7334]:9777"));
+
 	tal_free(ctx);
 	return 0;
 }

common/wireaddr.c

@@ -38,7 +38,7 @@ void towire_wireaddr(u8 **pptr, const struct wireaddr *addr)
 	towire_u16(pptr, addr->port);
 }
 
-static char *fmt_wireaddr(const tal_t *ctx, const struct wireaddr *a)
+char *fmt_wireaddr(const tal_t *ctx, const struct wireaddr *a)
 {
 	char addrstr[INET6_ADDRSTRLEN];
 	char *ret, *hex;
@@ -51,7 +51,7 @@ static char *fmt_wireaddr(const tal_t *ctx, const struct wireaddr *a)
 	case ADDR_TYPE_IPV6:
 		if (!inet_ntop(AF_INET6, a->addr, addrstr, INET6_ADDRSTRLEN))
 			return "Unprintable-ipv6-address";
-		return tal_fmt(ctx, "%s:%u", addrstr, a->port);
+		return tal_fmt(ctx, "[%s]:%u", addrstr, a->port);
 	case ADDR_TYPE_PADDING:
 		break;
 	}

common/wireaddr.h

@@ -44,4 +44,6 @@ bool fromwire_wireaddr(const u8 **cursor, size_t *max, struct wireaddr *addr);
 bool parse_ip_port(tal_t *ctx, const char *arg, char **ip, u16 *port);
 bool parse_wireaddr(const char *arg, struct wireaddr *addr, u16 port);
 
+char *fmt_wireaddr(const tal_t *ctx, const struct wireaddr *a);
+
 #endif /* LIGHTNING_COMMON_WIREADDR_H */