connectd: resolve ADDR_TYPE_DNS

This will resolve ADDR_TYPE_DNS wireaddr by expanding connect->addrs with one
new wireaddr ADDR_INTERNAL_WIREADDR per DNS result and calling recursion

connectd/connectd.c

@@ -788,6 +788,9 @@ static void try_connect_one_addr(struct connecting *connect)
 	bool use_proxy = connect->daemon->always_use_proxy;
 	const struct wireaddr_internal *addr = &connect->addrs[connect->addrnum];
 	struct io_conn *conn;
+	struct addrinfo hints, *ais, *aii;
+	struct wireaddr_internal addrhint;
+	int gai_err;
 
 	/* In case we fail without a connection, make destroy_io_conn happy */
 	connect->conn = NULL;
@@ -836,8 +839,45 @@ static void try_connect_one_addr(struct connecting *connect)
 			af = AF_INET6;
 			break;
 		case ADDR_TYPE_DNS:
-			// TODO: resolve with getaddrinfo and set af
-			break;
+			/* Resolve with getaddrinfo */
+			memset(&hints, 0, sizeof(hints));
+			hints.ai_socktype = SOCK_STREAM;
+			hints.ai_family = AF_UNSPEC;
+			hints.ai_protocol = 0;
+			hints.ai_flags = AI_ADDRCONFIG;
+			gai_err = getaddrinfo((char *)addr->u.wireaddr.addr,
+					      tal_fmt(tmpctx, "%d",
+						      addr->u.wireaddr.port),
+					      &hints, &ais);
+			if (gai_err != 0)
+				status_failed(STATUS_FAIL_INTERNAL_ERROR,
+					      gai_strerror(gai_err));
+			/* create new addrhints on-the-fly per result ... */
+			for (aii = ais; aii; aii = aii->ai_next) {
+				memset(&addrhint, 0, sizeof(addrhint));
+				addrhint.itype = ADDR_INTERNAL_WIREADDR;
+				addrhint.u.wireaddr.port = addr->u.wireaddr.port;
+				if (aii->ai_family == AF_INET) {
+					addrhint.u.wireaddr.type = ADDR_TYPE_IPV4;
+					addrhint.u.wireaddr.addrlen = 4;
+					memcpy(&addrhint.u.wireaddr.addr,
+					       aii->ai_addr, 4);
+				} else if (aii->ai_family == AF_INET6) {
+					addrhint.u.wireaddr.type = ADDR_TYPE_IPV6;
+					addrhint.u.wireaddr.addrlen = 16;
+					memcpy(&addrhint.u.wireaddr.addr,
+					       aii->ai_addr, 16);
+				} else {
+					/* skip unsupported ai_family */
+					continue;
+				}
+				tal_arr_expand(&connect->addrs, addrhint);
+			}
+			freeaddrinfo(ais);
+			/* ... and continue recursion */
+			connect->addrnum++;
+			try_connect_one_addr(connect);
+			return;
 		}
 	}