ccan/io: io_connect()

Not a perfect solution (we'd ideally want to go to another plan
immediately, but that would involve a malloc).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/io/io.c

@@ -9,6 +9,8 @@
 #include <stdlib.h>
 #include <assert.h>
 #include <poll.h>
+#include <unistd.h>
+#include <fcntl.h>
 
 void *io_loop_return;
 
@@ -337,6 +339,59 @@ struct io_plan io_write_partial_(const void *data, size_t *len,
 	return plan;
 }
 
+static int already_connected(int fd, struct io_plan *plan)
+{
+	return io_debug_io(1);
+}
+
+static int do_connect(int fd, struct io_plan *plan)
+{
+	int err, ret;
+	socklen_t len = sizeof(err);
+
+	/* Has async connect finished? */
+	ret = getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &len);
+	if (ret < 0)
+		return -1;
+
+	if (err == 0) {
+		/* Restore blocking if it was initially. */
+		fcntl(fd, F_SETFD, plan->u.len_len.len1);
+		return 1;
+	}
+	return 0;
+}
+
+struct io_plan io_connect_(int fd, const struct addrinfo *addr,
+			   struct io_plan (*cb)(struct io_conn*, void *),
+			   void *arg)
+{
+	struct io_plan plan;
+
+	assert(cb);
+
+	plan.next = cb;
+	plan.next_arg = arg;
+
+	/* Save old flags, set nonblock if not already. */
+	plan.u.len_len.len1 = fcntl(fd, F_GETFD);
+	fcntl(fd, F_SETFD, plan.u.len_len.len1 | O_NONBLOCK);
+
+	/* Immediate connect can happen. */
+	if (connect(fd, addr->ai_addr, addr->ai_addrlen) == 0) {
+		/* Dummy will be called immediately. */
+		plan.pollflag = POLLOUT;
+		plan.io = already_connected;
+	} else {
+		if (errno != EINPROGRESS)
+			return io_close_();
+
+		plan.pollflag = POLLIN;
+		plan.io = do_connect;
+	}
+	return plan;
+}
+
 struct io_plan io_idle_(void)
 {
 	struct io_plan plan;

ccan/io/io.h

@@ -160,6 +160,31 @@ struct io_plan io_write_partial_(const void *data, size_t *len,
 				 struct io_plan (*cb)(struct io_conn *, void*),
 				 void *arg);
 
+/**
+ * io_connect - plan to connect to a listening socket.
+ * @fd: file descriptor.
+ * @addr: where to connect.
+ * @cb: function to call once it's done.
+ * @arg: @cb argument
+ *
+ * This initiates a connection, and creates a plan for
+ * (asynchronously).  completing it.  Once complete, @len is updated
+ * and the @cb function will be called: on an error, the finish
+ * function is called instead.
+ *
+ * Note that the connect may actually be done immediately.
+ */
+struct addrinfo;
+#define io_connect(fd, addr, cb, arg)					\
+	io_debug(io_connect_((fd), (addr),				\
+			     typesafe_cb_preargs(struct io_plan, void *, \
+						 (cb), (arg),		\
+						 struct io_conn *),	\
+			     (arg)))
+struct io_plan io_connect_(int fd, const struct addrinfo *addr,
+			   struct io_plan (*cb)(struct io_conn *, void*),
+			   void *arg);
+
 /**
  * io_idle - plan to do nothing.
  *

ccan/io/test/run-09-connect-DEBUG.c

@@ -0,0 +1,8 @@
+#define DEBUG
+#define PORT "64009"
+#define main real_main
+int real_main(void);
+#include "run-09-connect.c"
+#undef main
+static bool always_debug(struct io_conn *conn) { return true; }
+int main(void) { io_debug_conn = always_debug; return real_main(); }

ccan/io/test/run-09-connect.c

@@ -0,0 +1,103 @@
+#include <ccan/io/io.h>
+/* Include the C files directly. */
+#include <ccan/io/poll.c>
+#include <ccan/io/io.c>
+#include <ccan/tap/tap.h>
+#include <sys/wait.h>
+#include <stdio.h>
+
+#ifndef PORT
+#define PORT "65009"
+#endif
+
+static struct io_listener *l;
+
+struct data {
+	int state;
+	char buf[10];
+};
+
+static struct io_plan closer(struct io_conn *conn, struct data *d)
+{
+	d->state++;
+	return io_close();
+}
+
+static struct io_plan connected(struct io_conn *conn, struct data *d2)
+{
+	ok1(d2->state == 0);
+	d2->state++;
+	return io_read(d2->buf, sizeof(d2->buf), closer, d2);
+}
+
+static void init_conn(int fd, struct data *d)
+{
+	ok1(d->state == 0);
+	d->state++;
+	io_new_conn(fd, io_write(d->buf, sizeof(d->buf), closer, d));
+	io_close_listener(l);
+}
+
+static int make_listen_fd(const char *port, struct addrinfo **info)
+{
+	int fd, on = 1;
+	struct addrinfo *addrinfo, hints;
+
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = AF_UNSPEC;
+	hints.ai_socktype = SOCK_STREAM;
+	hints.ai_flags = AI_PASSIVE;
+	hints.ai_protocol = 0;
+
+	if (getaddrinfo(NULL, port, &hints, &addrinfo) != 0)
+		return -1;
+
+	fd = socket(addrinfo->ai_family, addrinfo->ai_socktype,
+		    addrinfo->ai_protocol);
+	if (fd < 0)
+		return -1;
+
+	setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
+	if (bind(fd, addrinfo->ai_addr, addrinfo->ai_addrlen) != 0) {
+		close(fd);
+		return -1;
+	}
+	if (listen(fd, 1) != 0) {
+		close(fd);
+		return -1;
+	}
+	*info = addrinfo;
+	return fd;
+}
+
+int main(void)
+{
+	struct data *d = malloc(sizeof(*d)), *d2 = malloc(sizeof(*d2));
+	struct addrinfo *addrinfo;
+	int fd;
+
+	/* This is how many tests you plan to run */
+	plan_tests(8);
+	d->state = 0;
+	memset(d->buf, 'a', sizeof(d->buf));
+	fd = make_listen_fd(PORT, &addrinfo);
+	ok1(fd >= 0);
+	l = io_new_listener(fd, init_conn, d);
+	ok1(l);
+
+	fd = socket(addrinfo->ai_family, addrinfo->ai_socktype,
+		    addrinfo->ai_protocol);
+	d2->state = 0;
+	ok1(io_new_conn(fd, io_connect(fd, addrinfo, connected, d2)));
+
+	ok1(io_loop() == NULL);
+	ok1(d->state == 2);
+	ok1(d2->state == 2);
+
+	freeaddrinfo(addrinfo);
+	free(d);
+	free(d2);
+
+	/* This exits depending on whether all tests passed */
+	return exit_status();
+}