Move usbmuxd to its own folder

1 files changed, 731 insertions, 0 deletions

diff --git a/usbmuxd/device.c b/usbmuxd/device.c
new file mode 100644
index 0000000..c6ef75b
--- /dev/null
+++ b/usbmuxd/device.c
@@ -0,0 +1,731 @@
+/*
+	usbmuxd - iPhone/iPod Touch USB multiplex server daemon
+
+Copyright (C) 2009	Hector Martin "marcan" <hector@marcansoft.com>
+
+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 or version 3.
+
+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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+*/
+
+#define _BSD_SOURCE
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <sys/time.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <inttypes.h>
+#include "device.h"
+#include "client.h"
+#include "usb.h"
+#include "log.h"
+
+int next_device_id;
+
+#define DEV_PKTBUF_SIZE 65536
+
+#define CONN_INBUF_SIZE		262144
+#define CONN_OUTBUF_SIZE	65536
+
+#define ACK_TIMEOUT 60
+
+enum mux_protocol {
+	MUX_PROTO_VERSION = 0,
+	MUX_PROTO_TCP = IPPROTO_TCP,
+};
+
+enum mux_dev_state {
+	MUXDEV_INIT,	// sent version packet
+	MUXDEV_ACTIVE,	// received version packet, active
+	MUXDEV_DEAD		// dead
+};
+
+enum mux_conn_state {
+	CONN_CONNECTING,	// SYN
+	CONN_CONNECTED,		// SYN/SYNACK/ACK -> active
+	CONN_REFUSED,		// RST received during SYN
+	CONN_DYING,			// RST received
+	CONN_DEAD			// being freed; used to prevent infinite recursion between client<->device freeing
+};
+
+struct mux_header
+{
+	uint32_t protocol;
+	uint32_t length;
+};
+
+struct version_header
+{
+	uint32_t major;
+	uint32_t minor;
+	uint32_t padding;
+};
+
+struct mux_device;
+
+#define CONN_ACK_PENDING 1
+
+struct mux_connection
+{
+	struct mux_device *dev;
+	struct mux_client *client;
+	enum mux_conn_state state;
+	uint16_t sport, dport;
+	uint32_t tx_seq, tx_ack, tx_acked, tx_win;
+	uint32_t rx_seq, rx_recvd, rx_ack, rx_win;
+	int max_payload;
+	int sendable;
+	int flags;
+	unsigned char *ib_buf;
+	int ib_size;
+	int ib_capacity;
+	unsigned char *ob_buf;
+	int ob_capacity;
+	short events;
+	uint64_t last_ack_time;
+};
+
+struct mux_device
+{
+	struct usb_device *usbdev;
+	int id;
+	enum mux_dev_state state;
+	struct collection connections;
+	uint16_t next_sport;
+	unsigned char *pktbuf;
+	int pktlen;
+};
+
+static struct collection device_list;
+
+uint64_t mstime64(void)
+{
+	struct timeval tv;
+	gettimeofday(&tv, NULL);
+	return tv.tv_sec * 1000 + tv.tv_usec / 1000;
+}
+
+static int get_next_device_id(void)
+{
+	while(1) {
+		int ok = 1;
+		FOREACH(struct mux_device *dev, &device_list) {
+			if(dev->id == next_device_id) {
+				next_device_id++;
+				ok = 0;
+				break;
+			}
+		} ENDFOREACH
+		if(ok)
+			return next_device_id++;
+	}
+}
+
+static int send_packet(struct mux_device *dev, enum mux_protocol proto, void *header, const void *data, int length)
+{
+	unsigned char *buffer;
+	int hdrlen;
+	int res;
+	
+	switch(proto) {
+		case MUX_PROTO_VERSION:
+			hdrlen = sizeof(struct version_header);
+			break;
+		case MUX_PROTO_TCP:
+			hdrlen = sizeof(struct tcphdr);
+			break;
+		default:
+			usbmuxd_log(LL_ERROR, "Invalid protocol %d for outgoing packet (dev %d hdr %p data %p len %d)", proto, dev->id, header, data, length);
+			return -1;
+	}
+	usbmuxd_log(LL_SPEW, "send_packet(%d, 0x%x, %p, %p, %d)", dev->id, proto, header, data, length);
+	
+	int total = sizeof(struct mux_header) + hdrlen + length;
+	
+	if(total > USB_MTU) {
+		usbmuxd_log(LL_ERROR, "Tried to send packet larger than USB MTU (hdr %d data %d total %d) to device %d", hdrlen, length, total, dev->id);
+		return -1;
+	}
+	
+	buffer = malloc(total);
+	struct mux_header *mhdr = (struct mux_header *)buffer;
+	mhdr->protocol = htonl(proto);
+	mhdr->length = htonl(total);;
+	memcpy(buffer + sizeof(struct mux_header), header, hdrlen);
+	if(data && length)
+		memcpy(buffer + sizeof(struct mux_header) + hdrlen, data, length);
+	
+	if((res = usb_send(dev->usbdev, buffer, total)) < 0) {
+		usbmuxd_log(LL_ERROR, "usb_send failed while sending packet (len %d) to device %d: %d", total, dev->id, res);
+		free(buffer);
+		return res;
+	}
+	return total;
+}
+
+static uint16_t find_sport(struct mux_device *dev)
+{
+	if(collection_count(&dev->connections) >= 65535)
+		return 0; //insanity
+	
+	while(1) {
+		int ok = 1;
+		FOREACH(struct mux_connection *conn, &dev->connections) {
+			if(dev->next_sport == conn->sport) {
+				dev->next_sport++;
+				ok = 0;
+				break;
+			}
+		} ENDFOREACH
+		if(ok)
+			return dev->next_sport++;
+	}
+}
+
+static int send_tcp(struct mux_connection *conn, uint8_t flags, const unsigned char *data, int length)
+{
+	struct tcphdr th;
+	memset(&th, 0, sizeof(th));
+	th.th_sport = htons(conn->sport);
+	th.th_dport = htons(conn->dport);
+	th.th_seq = htonl(conn->tx_seq);
+	th.th_ack = htonl(conn->tx_ack);
+	th.th_flags = flags;
+	th.th_off = sizeof(th) / 4;
+	th.th_win = htons(conn->tx_win >> 8);
+	
+	usbmuxd_log(LL_DEBUG, "[OUT] dev=%d sport=%d dport=%d seq=%d ack=%d flags=0x%x window=%d[%d] len=%d",
+		conn->dev->id, conn->sport, conn->dport, conn->tx_seq, conn->tx_ack, flags, conn->tx_win, conn->tx_win >> 8, length);
+
+	int res = send_packet(conn->dev, MUX_PROTO_TCP, &th, data, length);
+	if(res >= 0) {
+		conn->tx_acked = conn->tx_ack;
+		conn->last_ack_time = mstime64();
+		conn->flags &= ~CONN_ACK_PENDING;
+	}
+	return res;
+}
+
+static void connection_teardown(struct mux_connection *conn)
+{
+	int res;
+	if(conn->state == CONN_DEAD)
+		return;
+	usbmuxd_log(LL_DEBUG, "connection_teardown dev %d sport %d dport %d", conn->dev->id, conn->sport, conn->dport);
+	if(conn->dev->state != MUXDEV_DEAD && conn->state != CONN_DYING && conn->state != CONN_REFUSED) {
+		res = send_tcp(conn, TH_RST, NULL, 0);
+		if(res < 0)
+			usbmuxd_log(LL_ERROR, "Error sending TCP RST to device %d (%d->%d)", conn->dev->id, conn->sport, conn->dport);
+	}
+	if(conn->client) {
+		if(conn->state == CONN_REFUSED || conn->state == CONN_CONNECTING) {
+			client_notify_connect(conn->client, RESULT_CONNREFUSED);
+		} else {
+			conn->state = CONN_DEAD;
+			client_close(conn->client);
+		}
+	}
+	if(conn->ib_buf)
+		free(conn->ib_buf);
+	if(conn->ob_buf)
+		free(conn->ob_buf);
+	collection_remove(&conn->dev->connections, conn);
+	free(conn);
+}
+
+int device_start_connect(int device_id, uint16_t dport, struct mux_client *client)
+{
+	struct mux_device *dev = NULL;
+	FOREACH(struct mux_device *cdev, &device_list) {
+		if(cdev->id == device_id) {
+			dev = cdev;
+			break;
+		}
+	} ENDFOREACH
+	if(!dev) {
+		usbmuxd_log(LL_WARNING, "Attempted to connect to nonexistent device %d", device_id);
+		return -RESULT_BADDEV;
+	}
+	
+	uint16_t sport = find_sport(dev);
+	if(!sport) {
+		usbmuxd_log(LL_WARNING, "Unable to allocate port for device %d", device_id);
+		return -RESULT_BADDEV;
+	}
+
+	struct mux_connection *conn;
+	conn = malloc(sizeof(struct mux_connection));
+	memset(conn, 0, sizeof(struct mux_connection));
+	
+	conn->dev = dev;
+	conn->client = client;
+	conn->state = CONN_CONNECTING;
+	conn->sport = sport;
+	conn->dport = dport;
+	conn->tx_seq = 0;
+	conn->tx_ack = 0;
+	conn->tx_acked = 0;
+	conn->tx_win = 131072;
+	conn->rx_recvd = 0;
+	conn->flags = 0;
+	conn->max_payload = USB_MTU - sizeof(struct mux_header) - sizeof(struct tcphdr);
+	
+	conn->ob_buf = malloc(CONN_OUTBUF_SIZE);
+	conn->ob_capacity = CONN_OUTBUF_SIZE;
+	conn->ib_buf = malloc(CONN_INBUF_SIZE);
+	conn->ib_capacity = CONN_INBUF_SIZE;
+	conn->ib_size = 0;
+	
+	int res;
+	
+	res = send_tcp(conn, TH_SYN, NULL, 0);
+	if(res < 0) {
+		usbmuxd_log(LL_ERROR, "Error sending TCP SYN to device %d (%d->%d)", dev->id, sport, dport);
+		free(conn);
+		return -RESULT_CONNREFUSED; //bleh
+	}
+	collection_add(&dev->connections, conn);
+	return 0;
+}
+
+static void update_connection(struct mux_connection *conn)
+{
+	conn->sendable = conn->rx_win - (conn->tx_seq - conn->rx_ack);
+	
+	if(conn->sendable > conn->ob_capacity)
+		conn->sendable = conn->ob_capacity;
+	if(conn->sendable > conn->max_payload)
+		conn->sendable = conn->max_payload;
+	
+	if(conn->sendable > 0)
+		conn->events |= POLLIN;
+	else
+		conn->events &= ~POLLIN;
+
+	if(conn->ib_size)
+		conn->events |= POLLOUT;
+	else
+		conn->events &= ~POLLOUT;
+
+	if(conn->tx_acked != conn->tx_ack)
+		conn->flags |= CONN_ACK_PENDING;
+	else
+		conn->flags &= ~CONN_ACK_PENDING;
+
+	usbmuxd_log(LL_SPEW, "update_connection: sendable %d, events %d, flags %d", conn->sendable, conn->events, conn->flags);
+	client_set_events(conn->client, conn->events);
+}
+
+void device_client_process(int device_id, struct mux_client *client, short events)
+{
+	struct mux_connection *conn = NULL;
+	FOREACH(struct mux_device *dev, &device_list) {
+		if(dev->id == device_id) {
+			FOREACH(struct mux_connection *lconn, &dev->connections) {
+				if(lconn->client == client) {
+					conn = lconn;
+					break;
+				}
+			} ENDFOREACH
+			break;
+		}
+	} ENDFOREACH
+
+	if(!conn) {
+		usbmuxd_log(LL_WARNING, "Could not find connection for device %d client %p", device_id, client);
+		return;
+	}
+	usbmuxd_log(LL_SPEW, "device_client_process (%d)", events);
+	
+	int res;
+	int size;
+	if(events & POLLOUT) {
+		size = client_write(conn->client, conn->ib_buf, conn->ib_size);
+		if(size <= 0) {
+			usbmuxd_log(LL_DEBUG, "error writing to client (%d)", size);
+			connection_teardown(conn);
+			return;
+		}
+		conn->tx_ack += size;
+		if(size == conn->ib_size) {
+			conn->ib_size = 0;
+		} else {
+			conn->ib_size -= size;
+			memmove(conn->ib_buf, conn->ib_buf + size, conn->ib_size);
+		}
+	}
+	if(events & POLLIN) {
+		size = client_read(conn->client, conn->ob_buf, conn->sendable);
+		if(size <= 0) {
+			usbmuxd_log(LL_DEBUG, "error reading from client (%d)", size);
+			connection_teardown(conn);
+			return;
+		}
+		res = send_tcp(conn, TH_ACK, conn->ob_buf, size);
+		if(res < 0) {
+			connection_teardown(conn);
+			return;
+		}
+		conn->tx_seq += size;
+	}
+
+	update_connection(conn);
+}
+
+static void connection_device_input(struct mux_connection *conn, unsigned char *payload, int payload_length)
+{
+	if((conn->ib_size + payload_length) > conn->ib_capacity) {
+		usbmuxd_log(LL_ERROR, "Input buffer overflow on device %d connection %d->%d (space=%d, payload=%d)", conn->dev->id, conn->sport, conn->dport, conn->ib_capacity-conn->ib_size, payload_length);
+		connection_teardown(conn);
+		return;
+	}
+	memcpy(conn->ib_buf + conn->ib_size, payload, payload_length);
+	conn->ib_size += payload_length;
+	conn->rx_recvd += payload_length;
+	update_connection(conn);
+}
+
+void device_abort_connect(int device_id, struct mux_client *client)
+{
+	FOREACH(struct mux_device *dev, &device_list) {
+		if(dev->id == device_id) {
+			FOREACH(struct mux_connection *conn, &dev->connections) {
+				if(conn->client == client) {
+					connection_teardown(conn);
+					return;
+				}
+			} ENDFOREACH
+			usbmuxd_log(LL_WARNING, "Attempted to abort for nonexistent connection for device %d", device_id);
+			return;
+		}
+	} ENDFOREACH
+	usbmuxd_log(LL_WARNING, "Attempted to abort connection for nonexistent device %d", device_id);
+}
+
+static void device_version_input(struct mux_device *dev, struct version_header *vh)
+{
+	if(dev->state != MUXDEV_INIT) {
+		usbmuxd_log(LL_WARNING, "Version packet from already initialized device %d", dev->id);
+		return;
+	}
+	vh->major = ntohl(vh->major);
+	vh->minor = ntohl(vh->minor);
+	if(vh->major != 1 || vh->minor != 0) {
+		usbmuxd_log(LL_ERROR, "Device %d has unknown version %d.%d\n", dev->id, vh->major, vh->minor);
+		collection_remove(&device_list, dev);
+		free(dev);
+		return;
+	}
+	usbmuxd_log(LL_NOTICE, "Connected to v%d.%d device %d on location 0x%x with serial number %s", vh->major, vh->minor, dev->id, usb_get_location(dev->usbdev), usb_get_serial(dev->usbdev));
+	dev->state = MUXDEV_ACTIVE;
+	collection_init(&dev->connections);
+	struct device_info info;
+	info.id = dev->id;
+	info.location = usb_get_location(dev->usbdev);
+	info.serial = usb_get_serial(dev->usbdev);
+	info.pid = usb_get_pid(dev->usbdev);
+	client_device_add(&info);
+}
+
+static void device_tcp_input(struct mux_device *dev, struct tcphdr *th, unsigned char *payload, int payload_length)
+{
+	usbmuxd_log(LL_DEBUG, "[IN] dev=%d sport=%d dport=%d seq=%d ack=%d flags=0x%x window=%d[%d] len=%d",
+		dev->id, ntohs(th->th_sport), ntohs(th->th_dport), ntohl(th->th_seq), ntohl(th->th_ack), th->th_flags, ntohs(th->th_win) << 8, ntohs(th->th_win), payload_length);
+	
+	uint16_t sport = ntohs(th->th_dport);
+	uint16_t dport = ntohs(th->th_sport);
+	struct mux_connection *conn = NULL;
+	FOREACH(struct mux_connection *lconn, &dev->connections) {
+		if(lconn->sport == sport && lconn->dport == dport) {
+			conn = lconn;
+			break;
+		}
+	} ENDFOREACH
+	
+	if(!conn) {
+		usbmuxd_log(LL_WARNING, "No connection for device %d incoming packet %d->%d", dev->id, dport, sport);
+		return;
+	}
+	
+	conn->rx_seq = ntohl(th->th_seq);
+	conn->rx_ack = ntohl(th->th_ack);
+	conn->rx_win = ntohs(th->th_win) << 8;
+	
+	if(th->th_flags & TH_RST) {
+		char *buf = malloc(payload_length+1);
+		memcpy(buf, payload, payload_length);
+		if(payload_length && (buf[payload_length-1] == '\n'))
+			buf[payload_length-1] = 0;
+		buf[payload_length] = 0;
+		usbmuxd_log(LL_DEBUG, "RST reason: %s", buf);
+		free(buf);
+	}
+	
+	if(conn->state == CONN_CONNECTING) {
+		if(th->th_flags != (TH_SYN|TH_ACK)) {
+			if(th->th_flags & TH_RST)
+				conn->state = CONN_REFUSED;
+			usbmuxd_log(LL_INFO, "Connection refused by device %d (%d->%d)", dev->id, sport, dport);
+			connection_teardown(conn); //this also sends the notification to the client
+		} else {
+			conn->tx_seq++;
+			conn->tx_ack++;
+			conn->rx_recvd = conn->rx_seq;
+			if(send_tcp(conn, TH_ACK, NULL, 0) < 0) {
+				usbmuxd_log(LL_ERROR, "Error sending TCP ACK to device %d (%d->%d)", dev->id, sport, dport);
+				connection_teardown(conn);
+				return;
+			}
+			conn->state = CONN_CONNECTED;
+			if(client_notify_connect(conn->client, RESULT_OK) < 0) {
+				conn->client = NULL;
+				connection_teardown(conn);
+			}
+			update_connection(conn);
+		}
+	} else if(conn->state == CONN_CONNECTED) {
+		if(th->th_flags != TH_ACK) {
+			usbmuxd_log(LL_INFO, "Connection reset by device %d (%d->%d)", dev->id, sport, dport);
+			if(th->th_flags & TH_RST)
+				conn->state = CONN_DYING;
+			connection_teardown(conn);
+		} else {
+			connection_device_input(conn, payload, payload_length);
+		}
+	}
+}
+
+void device_data_input(struct usb_device *usbdev, unsigned char *buffer, int length)
+{
+	struct mux_device *dev = NULL;
+	FOREACH(struct mux_device *tdev, &device_list) {
+		if(tdev->usbdev == usbdev) {
+			dev = tdev;
+			break;
+		}
+	} ENDFOREACH
+	if(!dev) {
+		usbmuxd_log(LL_WARNING, "Cannot find device entry for RX input from USB device %p on location 0x%x", usbdev, usb_get_location(usbdev));
+		return;
+	}
+	
+	if(!length)
+		return;
+	
+	usbmuxd_log(LL_SPEW, "Mux data input for device %p: %p len %d", dev, buffer, length);
+
+	// handle broken up transfers
+	if(dev->pktlen) {
+		memcpy(dev->pktbuf + dev->pktlen, buffer, length);
+		struct mux_header *mhdr = (struct mux_header *)dev->pktbuf;
+		if((length < USB_MRU) || (ntohl(mhdr->length) == length)) {
+			buffer = dev->pktbuf;
+			length += dev->pktlen;
+			dev->pktlen = 0;
+			usbmuxd_log(LL_SPEW, "Gathered mux data from buffer (total size: %d)", length);
+		} else {
+			dev->pktlen += length;
+			usbmuxd_log(LL_SPEW, "Appended mux data to buffer (total size: %d)", dev->pktlen);
+			return;
+		}
+	} else {
+		struct mux_header *mhdr = (struct mux_header *)buffer;
+		if((length == USB_MRU) && (length < ntohl(mhdr->length))) {
+			memcpy(dev->pktbuf, buffer, length);
+			dev->pktlen = length;
+			usbmuxd_log(LL_SPEW, "Copied mux data to buffer (size: %d)", dev->pktlen);
+			return;
+		}
+	}
+	
+	struct mux_header *mhdr = (struct mux_header *)buffer;
+	
+	if(ntohl(mhdr->length) != length) {
+		usbmuxd_log(LL_ERROR, "Incoming packet size mismatch (dev %d, expected %d, got %d)", dev->id, ntohl(mhdr->length), length);
+		return;
+	}
+	
+	struct tcphdr *th;
+	unsigned char *payload;
+	int payload_length;
+	
+	switch(ntohl(mhdr->protocol)) {
+		case MUX_PROTO_VERSION:
+			device_version_input(dev, (struct version_header *)(mhdr+1));
+			break;
+		case MUX_PROTO_TCP:
+			th = (struct tcphdr *)(mhdr+1);
+			payload = (unsigned char *)(th+1);
+			payload_length = length - sizeof(struct tcphdr) - sizeof(struct mux_header);
+			device_tcp_input(dev, (struct tcphdr *)(mhdr+1), payload, payload_length);
+			break;
+		default:
+			usbmuxd_log(LL_ERROR, "Incoming packet for device %d has unknown protocol 0x%x)", dev->id, ntohl(mhdr->protocol));
+			break;
+	}
+	
+}
+
+int device_add(struct usb_device *usbdev)
+{
+	int res;
+	int id = get_next_device_id();
+	struct mux_device *dev;
+	usbmuxd_log(LL_NOTICE, "Connecting to new device on location 0x%x as ID %d", usb_get_location(usbdev), id);
+	dev = malloc(sizeof(struct mux_device));
+	dev->id = id;
+	dev->usbdev = usbdev;
+	dev->state = MUXDEV_INIT;
+	dev->next_sport = 1;
+	dev->pktbuf = malloc(DEV_PKTBUF_SIZE);
+	dev->pktlen = 0;
+	struct version_header vh;
+	vh.major = htonl(1);
+	vh.minor = htonl(0);
+	vh.padding = 0;
+	if((res = send_packet(dev, MUX_PROTO_VERSION, &vh, NULL, 0)) < 0) {
+		usbmuxd_log(LL_ERROR, "Error sending version request packet to device %d\n", id);
+		free(dev);
+		return res;
+	}
+	collection_add(&device_list, dev);
+	return 0;
+}
+
+void device_remove(struct usb_device *usbdev)
+{
+	FOREACH(struct mux_device *dev, &device_list) {
+		if(dev->usbdev == usbdev) {
+			usbmuxd_log(LL_NOTICE, "Removed device %d on location 0x%x", dev->id, usb_get_location(usbdev));
+			if(dev->state == MUXDEV_ACTIVE) {
+				dev->state = MUXDEV_DEAD;
+				FOREACH(struct mux_connection *conn, &dev->connections) {
+					connection_teardown(conn);
+				} ENDFOREACH
+				client_device_remove(dev->id);
+				collection_free(&dev->connections);
+			}
+			collection_remove(&device_list, dev);
+			free(dev->pktbuf);
+			free(dev);
+			return;
+		}
+	} ENDFOREACH
+	usbmuxd_log(LL_WARNING, "Cannot find device entry while removing USB device %p on location 0x%x", usbdev, usb_get_location(usbdev));
+}
+
+int device_get_count(void)
+{
+	int count = 0;
+	FOREACH(struct mux_device *dev, &device_list) {
+		if(dev->state == MUXDEV_ACTIVE)
+			count++;
+	} ENDFOREACH
+	return count;
+}
+
+int device_get_list(struct device_info *p)
+{
+	int count = 0;
+	FOREACH(struct mux_device *dev, &device_list) {
+		if(dev->state == MUXDEV_ACTIVE) {
+			p->id = dev->id;
+			p->serial = usb_get_serial(dev->usbdev);
+			p->location = usb_get_location(dev->usbdev);
+			p->pid = usb_get_pid(dev->usbdev);
+			count++;
+			p++;
+		}
+	} ENDFOREACH
+	return count;
+}
+
+int device_get_timeout(void)
+{
+	uint64_t oldest = (uint64_t)-1;
+	FOREACH(struct mux_device *dev, &device_list) {
+		if(dev->state == MUXDEV_ACTIVE) {
+			FOREACH(struct mux_connection *conn, &dev->connections) {
+				if((conn->state == CONN_CONNECTED) && (conn->flags & CONN_ACK_PENDING) && conn->last_ack_time < oldest)
+					oldest = conn->last_ack_time;
+			} ENDFOREACH
+		}
+	} ENDFOREACH
+	uint64_t ct = mstime64();
+	if(oldest == -1)
+		return 100000; //meh
+	if((ct - oldest) > ACK_TIMEOUT)
+		return 0;
+	return ACK_TIMEOUT - (ct - oldest);
+}
+
+void device_check_timeouts(void)
+{
+	uint64_t ct = mstime64();
+	FOREACH(struct mux_device *dev, &device_list) {
+		if(dev->state == MUXDEV_ACTIVE) {
+			FOREACH(struct mux_connection *conn, &dev->connections) {
+				if((conn->state == CONN_CONNECTED) && 
+						(conn->flags & CONN_ACK_PENDING) && 
+						(ct - conn->last_ack_time) > ACK_TIMEOUT) {
+					usbmuxd_log(LL_DEBUG, "Sending ACK due to expired timeout (%" PRIu64 " -> %" PRIu64 ")", conn->last_ack_time, ct);
+					if(send_tcp(conn, TH_ACK, NULL, 0) < 0) {
+						usbmuxd_log(LL_ERROR, "Error sending TCP ACK to device %d (%d->%d)", dev->id, conn->sport, conn->dport);
+						connection_teardown(conn);
+					}
+				}
+			} ENDFOREACH
+		}
+	} ENDFOREACH
+}
+
+void device_init(void)
+{
+	usbmuxd_log(LL_DEBUG, "device_init");
+	collection_init(&device_list);
+	next_device_id = 1;
+}
+
+void device_kill_connections(void)
+{
+	usbmuxd_log(LL_DEBUG, "device_kill_connections");
+	FOREACH(struct mux_device *dev, &device_list) {
+		if(dev->state != MUXDEV_INIT) {
+			FOREACH(struct mux_connection *conn, &dev->connections) {
+				connection_teardown(conn);
+			} ENDFOREACH
+		}
+	} ENDFOREACH
+	// give USB a while to send the final connection RSTs and the like
+	usb_process_timeout(100);
+}
+
+void device_shutdown(void)
+{
+	usbmuxd_log(LL_DEBUG, "device_shutdown");
+	FOREACH(struct mux_device *dev, &device_list) {
+		FOREACH(struct mux_connection *conn, &dev->connections) {
+			connection_teardown(conn);
+		} ENDFOREACH
+		collection_free(&dev->connections);
+		collection_remove(&device_list, dev);
+		free(dev);
+	} ENDFOREACH
+	collection_free(&device_list);
+}