tcp_connect: generic library for establishing TCP connections

2 files changed, 348 insertions, 0 deletions

diff --git a/src/tcp_connect.c b/src/tcp_connect.c
new file mode 100644
index 000000000..bea823955
--- /dev/null
+++ b/src/tcp_connect.c
@@ -0,0 +1,252 @@
+/*
+ * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "tcp_connect.h"
+#include "fd_util.h"
+#include "io_thread.h"
+#include "glib_compat.h"
+#include "glib_socket.h"
+
+#include <assert.h>
+#include <errno.h>
+
+#ifdef WIN32
+#define WINVER 0x0501
+#include <ws2tcpip.h>
+#include <winsock.h>
+#else
+#include <sys/socket.h>
+#include <unistd.h>
+#endif
+
+struct tcp_connect {
+	const struct tcp_connect_handler *handler;
+	void *handler_ctx;
+
+	int fd;
+	GSource *source;
+
+	unsigned timeout_ms;
+	GSource *timeout_source;
+};
+
+static bool
+is_in_progress_errno(int e)
+{
+#ifdef WIN32
+	return e == WSAEINPROGRESS || e == WSAEWOULDBLOCK;
+#else
+	return e == EINPROGRESS;
+#endif
+}
+
+static gboolean
+tcp_connect_event(G_GNUC_UNUSED GIOChannel *source,
+		  G_GNUC_UNUSED GIOCondition condition,
+		  gpointer data)
+{
+	struct tcp_connect *c = data;
+
+	assert(c->source != NULL);
+	assert(c->timeout_source != NULL);
+
+	/* clear the socket source */
+	g_source_unref(c->source);
+	c->source = NULL;
+
+	/* delete the timeout source */
+	g_source_destroy(c->timeout_source);
+	g_source_unref(c->timeout_source);
+	c->timeout_source = NULL;
+
+	/* obtain the connect result */
+	int s_err = 0;
+	socklen_t s_err_size = sizeof(s_err);
+	if (getsockopt(c->fd, SOL_SOCKET, SO_ERROR,
+		       (char*)&s_err, &s_err_size) < 0)
+		s_err = errno;
+
+	if (s_err == 0) {
+		/* connection established successfully */
+
+		c->handler->success(c->fd, c->handler_ctx);
+	} else {
+		/* there was an I/O error; close the socket and pass
+		   the error to the handler */
+
+		close_socket(c->fd);
+
+		GError *error =
+			g_error_new_literal(g_file_error_quark(), s_err,
+					    g_strerror(s_err));
+		c->handler->error(error, c->handler_ctx);
+	}
+
+	return false;
+}
+
+static gboolean
+tcp_connect_timeout(gpointer data)
+{
+	struct tcp_connect *c = data;
+
+	assert(c->source != NULL);
+	assert(c->timeout_source != NULL);
+
+	/* clear the timeout source */
+	g_source_unref(c->timeout_source);
+	c->timeout_source = NULL;
+
+	/* delete the socket source */
+	g_source_destroy(c->source);
+	g_source_unref(c->source);
+	c->source = NULL;
+
+	/* report timeout to handler */
+	c->handler->timeout(c->handler_ctx);
+
+	return false;
+}
+
+static gpointer
+tcp_connect_init(gpointer data)
+{
+	struct tcp_connect *c = data;
+
+	/* create a connect source */
+	GIOChannel *channel = g_io_channel_new_socket(c->fd);
+	c->source = g_io_create_watch(channel, G_IO_OUT);
+	g_io_channel_unref(channel);
+
+	g_source_set_callback(c->source, (GSourceFunc)tcp_connect_event, c,
+			      NULL);
+	g_source_attach(c->source, io_thread_context());
+
+	/* create a timeout source */
+	if (c->timeout_ms > 0)
+		c->timeout_source =
+			io_thread_timeout_add(c->timeout_ms,
+					      tcp_connect_timeout, c);
+
+	return NULL;
+}
+
+void
+tcp_connect_address(const struct sockaddr *address, size_t address_length,
+		    unsigned timeout_ms,
+		    const struct tcp_connect_handler *handler, void *ctx,
+		    struct tcp_connect **handle_r)
+{
+	assert(address != NULL);
+	assert(address_length > 0);
+	assert(handler != NULL);
+	assert(handler->success != NULL);
+	assert(handler->error != NULL);
+	assert(handler->canceled != NULL);
+	assert(handler->timeout != NULL || timeout_ms == 0);
+	assert(handle_r != NULL);
+	assert(*handle_r == NULL);
+
+	int fd = socket_cloexec_nonblock(address->sa_family, SOCK_STREAM, 0);
+	if (fd < 0) {
+		GError *error =
+			g_error_new_literal(g_file_error_quark(), errno,
+					    g_strerror(errno));
+		handler->error(error, ctx);
+		return;
+	}
+
+	int ret = connect(fd, address, address_length);
+	if (ret >= 0) {
+		/* quick connect, no I/O thread */
+		handler->success(fd, ctx);
+		return;
+	}
+
+	if (!is_in_progress_errno(errno)) {
+		GError *error =
+			g_error_new_literal(g_file_error_quark(), errno,
+					    g_strerror(errno));
+		close_socket(fd);
+		handler->error(error, ctx);
+		return;
+	}
+
+	/* got EINPROGRESS, use the I/O thread to wait for the
+	   operation to finish */
+
+	struct tcp_connect *c = g_new(struct tcp_connect, 1);
+	c->handler = handler;
+	c->handler_ctx = ctx;
+	c->fd = fd;
+	c->source = NULL;
+	c->timeout_ms = timeout_ms;
+	c->timeout_source = NULL;
+
+	*handle_r = c;
+
+	io_thread_call(tcp_connect_init, c);
+}
+
+static gpointer
+tcp_connect_cancel_callback(gpointer data)
+{
+	struct tcp_connect *c = data;
+
+	assert((c->source == NULL) == (c->timeout_source == NULL));
+
+	if (c->source == NULL)
+		return NULL;
+
+	/* delete the socket source */
+	g_source_destroy(c->source);
+	g_source_unref(c->source);
+	c->source = NULL;
+
+	/* delete the timeout source */
+	g_source_destroy(c->timeout_source);
+	g_source_unref(c->timeout_source);
+	c->timeout_source = NULL;
+
+	/* close the socket */
+	close_socket(c->fd);
+
+	/* notify the handler */
+	c->handler->canceled(c->handler_ctx);
+
+	return NULL;
+}
+
+void
+tcp_connect_cancel(struct tcp_connect *c)
+{
+	if (c->source == NULL)
+		return;
+
+	io_thread_call(tcp_connect_cancel_callback, c);
+}
+
+void
+tcp_connect_free(struct tcp_connect *c)
+{
+	assert(c->source == NULL);
+
+	g_free(c);
+}
diff --git a/src/tcp_connect.h b/src/tcp_connect.h
new file mode 100644
index 000000000..bdbe85c14
--- /dev/null
+++ b/src/tcp_connect.h
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_TCP_CONNECT_H
+#define MPD_TCP_CONNECT_H
+
+#include <glib.h>
+
+struct sockaddr;
+
+struct tcp_connect_handler {
+	/**
+	 * The connection was established successfully.
+	 *
+	 * @param fd a file descriptor that must be closed with
+	 * close_socket() when finished
+	 */
+	void (*success)(int fd, void *ctx);
+
+	/**
+	 * An error has occurred.  The method is responsible for
+	 * freeing the GError.
+	 */
+	void (*error)(GError *error, void *ctx);
+
+	/**
+	 * The connection could not be established in the specified
+	 * time span.
+	 */
+	void (*timeout)(void *ctx);
+
+	/**
+	 * The operation was canceled before a result was available.
+	 */
+	void (*canceled)(void *ctx);
+};
+
+struct tcp_connect;
+
+/**
+ * Establish a TCP connection to the specified address.
+ *
+ * Note that the result may be available before this function returns.
+ *
+ * The caller must free this object with tcp_connect_free().
+ *
+ * @param timeout_ms time out after this number of milliseconds; 0
+ * means no timeout
+ * @param handle_r a handle that can be used to cancel the operation;
+ * the caller must initialize it to NULL
+ */
+void
+tcp_connect_address(const struct sockaddr *address, size_t address_length,
+		    unsigned timeout_ms,
+		    const struct tcp_connect_handler *handler, void *ctx,
+		    struct tcp_connect **handle_r);
+
+/**
+ * Cancel the operation.  It is possible that the result is delivered
+ * before the operation has been canceled; in that case, the
+ * canceled() handler method will not be invoked.
+ *
+ * Even after calling this function, tcp_connect_free() must still be
+ * called to free memory.
+ */
+void
+tcp_connect_cancel(struct tcp_connect *handle);
+
+/**
+ * Free memory used by this object.
+ *
+ * This function is not thread safe.  It must not be called while
+ * other threads are still working with it.  If no callback has been
+ * invoked so far, then you must call tcp_connect_cancel() to release
+ * I/O thread resources, before calling this function.
+ */
+void
+tcp_connect_free(struct tcp_connect *handle);
+
+#endif