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Diffstat (limited to 'src/usbmux.c')
| -rw-r--r-- | src/usbmux.c | 1259 |
1 files changed, 1259 insertions, 0 deletions
diff --git a/src/usbmux.c b/src/usbmux.c new file mode 100644 index 0000000..e86e3bc --- /dev/null +++ b/src/usbmux.c @@ -0,0 +1,1259 @@ +/* + * Copyright (c) 2008 Jing Su. All Rights Reserved. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library 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 + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ +#include <stdint.h> +#include <stdarg.h> +#include <stdlib.h> +#include <string.h> +#include <usb.h> +#include <stdio.h> +#include <arpa/inet.h> +#include <errno.h> +#include <pthread.h> +#include "usbmux.h" + +#define BULKIN 0x85 +#define BULKOUT 0x04 +#define HEADERLEN 28 + +static const uint8_t TCP_FIN = 1; +static const uint8_t TCP_SYN = 1 << 1; +static const uint8_t TCP_RST = 1 << 2; +static const uint8_t TCP_PSH = 1 << 3; +static const uint8_t TCP_ACK = 1 << 4; +static const uint8_t TCP_URG = 1 << 5; + +// I have trouble figuring out how to properly manage the windowing to +// the device. It keeps sending back 512 and seems to drop off a cliff +// when the device gets overwhelmed. In addition, the device likes to +// panic and send out RESETS before the window hits zero. Also, waiting +// for responses seems to not be a winning strategy. +// +// Since I'm not sure how in the hell to interpret the window sizes that +// the device is sending back to us, I've figured out some magic number +// constants which seem to work okay. +static const uint32_t WINDOW_MAX = 5 * 1024; +static const uint32_t WINDOW_INCREMENT = 512; + +typedef struct { + char *buffer; + int leftover; + int capacity; +} receivebuf_t; + +struct usbmux_device_int { + struct usb_dev_handle *usbdev; + struct usb_device *__device; + receivebuf_t usbReceive; +}; + +typedef struct { + uint32_t type, length, major, minor, allnull; +} usbmux_version_header; + +typedef struct { + uint32_t type, length; + uint16_t sport, dport; + uint32_t scnt, ocnt; + uint8_t offset, tcp_flags; + uint16_t window, nullnull, length16; +} usbmux_tcp_header; + +struct usbmux_client_int { + usbmux_tcp_header *header; + usbmux_device_t device; + + char *recv_buffer; + int r_len; + pthread_cond_t wait; + + // this contains a conditional variable which usb-writers can wait + // on while waiting for window updates from the device. + pthread_cond_t wr_wait; + // I'm going to do something really cheesy here. We are going to + // just record the most recent scnt that we are expecting to hear + // back on. We will actually halt progress by limiting the number + // of outstanding un-acked bulk sends that we have beamed out. + uint32_t wr_pending_scnt; + long wr_window; + + pthread_mutex_t mutex; + + // this variable is not protected by the mutex. This will always + // be E_SUCCESS, unless an error of some kind breaks this stream. + // this will then be set to the error that caused the broken stream. + // no further operations other than free_client will be allowed. + int error; + + int cleanup; +}; + + +static pthread_mutex_t usbmuxmutex = PTHREAD_MUTEX_INITIALIZER; +static usbmux_client_t *connlist = NULL; +static int clients = 0; + + +/** + */ +int toto_debug = 0; + +void usbmux_set_debug(int e) +{ + toto_debug = e; +} + +void log_debug_msg(const char *format, ...) +{ +#ifndef STRIP_DEBUG_CODE + va_list args; + /* run the real fprintf */ + va_start(args, format); + + if (toto_debug) + vfprintf(stderr, format, args); + + va_end(args); +#endif +} + +#ifdef DEBUG +/** + * for debugging purposes. + */ +static void print_buffer(const char *data, const int length) +{ + if (toto_debug <= 0) { + return; + } + int i; + int j; + unsigned char c; + + for (i = 0; i < length; i += 16) { + printf("%04x: ", i); + for (j = 0; j < 16; j++) { + if (i + j >= length) { + printf(" "); + continue; + } + printf("%02hhx ", *(data + i + j)); + } + printf(" | "); + for (j = 0; j < 16; j++) { + if (i + j >= length) + break; + c = *(data + i + j); + if ((c < 32) || (c > 127)) { + printf("."); + continue; + } + printf("%c", c); + } + printf("\n"); + } + printf("\n"); +} +#endif + +void hton_header(usbmux_tcp_header * hdr) +{ + if (hdr) { + hdr->length = htonl(hdr->length); + hdr->scnt = htonl(hdr->scnt); + hdr->ocnt = htonl(hdr->ocnt); + hdr->length16 = htons(hdr->length16); + } +} + +void ntoh_header(usbmux_tcp_header * hdr) +{ + if (hdr) { + hdr->length = ntohl(hdr->length); + hdr->scnt = ntohl(hdr->scnt); + hdr->ocnt = ntohl(hdr->ocnt); + hdr->length16 = ntohs(hdr->length16); + } +} + +/** Creates a USBMux header containing version information + * + * @return A USBMux header + */ +usbmux_version_header *version_header() +{ + usbmux_version_header *version = + (usbmux_version_header *) malloc(sizeof(usbmux_version_header)); + version->type = 0; + version->length = htonl(20); + version->major = htonl(1); + version->minor = 0; + version->allnull = 0; + return version; +} + +/** + * This function sets the configuration of the given device to 3 + * and claims the interface 1. If usb_set_configuration fails, it detaches + * the kernel driver that blocks the device, and retries configuration. + * + * @param device which device to configure + */ +static int usbmux_config_usb_device(usbmux_device_t device) +{ + int ret; + int bytes; + char buf[512]; + +#if 0 + log_debug_msg("checking configuration...\n"); + if (device->__device->config->bConfigurationValue != 3) { + log_debug_msg + ("WARNING: usb device configuration is not 3 as expected!\n"); + } + + log_debug_msg("setting configuration...\n"); + ret = usb_set_configuration(device->device, 3); + if (ret != 0) { + log_debug_msg("Hm, usb_set_configuration returned %d: %s\n", ret, + strerror(-ret)); +#if LIBUSB_HAS_GET_DRIVER_NP + log_debug_msg("trying to fix:\n"); + log_debug_msg("-> detaching kernel driver... "); + ret = + usb_detach_kernel_driver_np(device->device, + device->__device->config-> + interface->altsetting-> + bInterfaceNumber); + if (ret != 0) { + log_debug_msg("usb_detach_kernel_driver_np returned %d: %s\n", + ret, strerror(-ret)); + } else { + log_debug_msg("done.\n"); + log_debug_msg("setting configuration again... "); + ret = usb_set_configuration(device->device, 3); + if (ret != 0) { + log_debug_msg + ("Error: usb_set_configuration returned %d: %s\n", ret, + strerror(-ret)); + log_debug_msg("--> trying to continue anyway...\n"); + } else { + log_debug_msg("done.\n"); + } + } +#else + log_debug_msg("--> trying to continue anyway...\n"); +#endif + } else { + log_debug_msg("done.\n"); + } +#endif + + log_debug_msg("claiming interface... "); + ret = usb_claim_interface(device->usbdev, 1); + if (ret != 0) { + log_debug_msg("Error: usb_claim_interface returned %d: %s\n", ret, + strerror(-ret)); + return -ENODEV; + } else { + log_debug_msg("done.\n"); + } + + do { + bytes = usb_bulk_read(device->usbdev, BULKIN, buf, 512, 800); + } while (bytes > 0); + + return 0; +} + +/** + * Given a USB bus and device number, returns a device handle to the device on + * that bus. To aid compatibility with future devices, this function does not + * check the vendor and device IDs! To do that, you should use + * usbmux_get_device() or a system-specific API (e.g. HAL). + * + * @param bus_n The USB bus number. + * @param dev_n The USB device number. + * @param device A pointer to a usbmux_device_t, which must be set to NULL upon + * calling usbmux_get_specific_device, which will be filled with a device + * descriptor on return. + * @return 0 if ok, otherwise a negative errno value. + */ +int usbmux_get_specific_device(int bus_n, int dev_n, + usbmux_device_t * device) +{ + struct usb_bus *bus; + struct usb_device *dev; + usbmux_version_header *version; + int bytes = 0; + + //check we can actually write in device + if (!device || (device && *device)) + return -EINVAL; + + usbmux_device_t newdevice = + (usbmux_device_t) malloc(sizeof(struct usbmux_device_int)); + + // Initialize the struct + newdevice->usbdev = NULL; + newdevice->__device = NULL; + + // don't forget these: + newdevice->usbReceive.buffer = NULL; + newdevice->usbReceive.leftover = 0; + newdevice->usbReceive.capacity = 0; + + // Initialize libusb + usb_init(); + usb_find_busses(); + usb_find_devices(); + + // Set the device configuration + for (bus = usb_get_busses(); bus; bus = bus->next) + //if (bus->location == bus_n) + for (dev = bus->devices; dev != NULL; dev = dev->next) + if (dev->devnum == dev_n) { + newdevice->__device = dev; + newdevice->usbdev = usb_open(newdevice->__device); + if (usbmux_config_usb_device(newdevice) == 0) { + goto found; + } + } + + usbmux_free_device(newdevice); + + log_debug_msg("usbmux_get_specific_device: device not found\n"); + return -ENODEV; + + found: + // Send the version command to the device + version = version_header(); + bytes = + usb_bulk_write(newdevice->usbdev, BULKOUT, (char *) version, + sizeof(*version), 800); + if (bytes < 20) { + log_debug_msg("%s: libusb did NOT send enough!\n", __func__); + if (bytes < 0) { + log_debug_msg("%s: libusb gave me the error %d: %s (%s)\n", + __func__, bytes, usb_strerror(), + strerror(-bytes)); + } + } + // Read the device's response + bytes = + usb_bulk_read(newdevice->usbdev, BULKIN, (char *) version, + sizeof(*version), 800); + + // Check for bad response + if (bytes < 20) { + free(version); + usbmux_free_device(newdevice); + log_debug_msg("%s: Invalid version message -- header too short.\n", + __func__); + if (bytes < 0) { + log_debug_msg("%s: libusb error message %d: %s (%s)\n", + __func__, bytes, usb_strerror(), + strerror(-bytes)); + return bytes; + } + return -EBADMSG; + } + // Check for correct version + if (ntohl(version->major) == 1 && ntohl(version->minor) == 0) { + // We're all ready to roll. + log_debug_msg("%s: success\n", __func__); + free(version); + *device = newdevice; + return 0; + } else { + // Bad header + usbmux_free_device(newdevice); + free(version); + log_debug_msg("%s: Received a bad header/invalid version number.", + __func__); + return -EBADMSG; + } + + // If it got to this point it's gotta be bad + log_debug_msg("%s: Unknown error.\n", __func__); + usbmux_free_device(newdevice); + free(version); + return -EBADMSG; // if it got to this point it's gotta be bad +} + +/** Cleans up an usbmux_device_t structure, then frees the structure itself. + * This is a library-level function; deals directly with the device to tear + * down relations, but otherwise is mostly internal. + * + * @param device A pointer to an usbmux_device_t structure. + */ +int usbmux_free_device(usbmux_device_t device) +{ + char buf[512]; + int bytes; + + if (!device) + return -EINVAL; + int ret = 0; + + if (device->usbdev) { + do { + bytes = usb_bulk_read(device->usbdev, BULKIN, buf, 512, 800); + } while (bytes > 0); + } + + if (bytes < 0) { + ret = bytes; + } + + if (device->usbReceive.buffer) { + free(device->usbReceive.buffer); + } + if (device->usbdev) { + usb_release_interface(device->usbdev, 1); + usb_close(device->usbdev); + ret = 0; + } + free(device); + + return ret; +} + + + +/** Sends data to the device + * This is a low-level (i.e. directly to device) function. + * + * @param device The device to send data to + * @param data The data to send + * @param datalen The length of the data + * @return The number of bytes sent, or -ERRNO on error + */ +int send_to_device(usbmux_device_t device, char *data, int datalen) +{ + if (!device) + return -EINVAL; + + int timeout = 1000; + int retrycount = 0; + int bytes = 0; + +#ifdef DEBUG +#ifdef DEBUG_MORE + printf("===============================\n%s: trying to send\n", + __func__); + print_buffer(data, datalen); + printf("===============================\n"); +#endif +#endif + do { + if (retrycount > 3) { + log_debug_msg + ("EPIC FAIL! aborting on retry count overload.\n"); + return -ECOMM; + } + + bytes = + usb_bulk_write(device->usbdev, BULKOUT, data, datalen, + timeout); + if (bytes == -ETIMEDOUT) { + // timed out waiting for write. + log_debug_msg("usb_bulk_write timeout error.\n"); + return bytes; + } else if (bytes < 0) { + log_debug_msg + ("usb_bulk_write failed with error. err:%d (%s)(%s)\n", + bytes, usb_strerror(), strerror(-bytes)); + return bytes; + } else if (bytes == 0) { + log_debug_msg("usb_bulk_write sent nothing. retrying.\n"); + timeout = timeout * 4; + retrycount++; + continue; + } else if (bytes < datalen) { + log_debug_msg + ("usb_bulk_write failed to send full dataload. %d of %d\n", + bytes, datalen); + timeout = timeout * 4; + retrycount++; + data += bytes; + datalen -= bytes; + continue; + } + } while (0); // fall out + +#ifdef DEBUG + if (bytes > 0) { + if (toto_debug > 0) { + printf(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"); + printf("%s: sent to device\n", __func__); + print_buffer(data, bytes); + printf(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"); + } + } +#endif + return bytes; +} + +/** Receives data from the device + * This function is a low-level (i.e. direct from device) function. + * + * @param device The device to receive data from + * @param data Where to put data read + * @param datalen How much data to read in + * @param timeout How many milliseconds to wait for data + * + * @return How many bytes were read in, or -1 on error. + */ +int recv_from_device_timeout(usbmux_device_t device, char *data, + int datalen, int timeoutmillis) +{ + if (!device) + return -EINVAL; + //log_debug_msg("%s: attempting to receive %i bytes\n", __func__, datalen); + + int bytes = + usb_bulk_read(device->usbdev, BULKIN, data, datalen, + timeoutmillis); + // There are some things which are errors, others which are no problem. + // It's not documented in libUSB, but it seems that the error values + // returned are just negated ERRNO values. + if (bytes < 0) { + if (bytes == -ETIMEDOUT) { + // ignore this. it just means timeout reached before we + // picked up any data. no problem. + return 0; + } else { + fprintf(stderr, "%s: libusb gave me the error %d: %s (%s)\n", + __func__, bytes, usb_strerror(), strerror(-bytes)); + log_debug_msg("%s: libusb gave me the error %d: %s (%s)\n", + __func__, bytes, usb_strerror(), + strerror(-bytes)); + } + return bytes; + } +#ifdef DEBUG + if (bytes > 0) { + if (toto_debug > 0) { + printf("<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + printf("%s: received from device:\n", __func__); + print_buffer(data, bytes); + printf("<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + } + } +#endif + + return bytes; +} + +/** Creates a USBMux packet for the given set of ports. + * + * @param s_port The source port for the connection. + * @param d_port The destination port for the connection. + * + * @return A USBMux packet + */ +usbmux_tcp_header *new_mux_packet(uint16_t s_port, uint16_t d_port) +{ + usbmux_tcp_header *conn = + (usbmux_tcp_header *) malloc(sizeof(usbmux_tcp_header)); + conn->type = htonl(6); + conn->length = HEADERLEN; + conn->sport = htons(s_port); + conn->dport = htons(d_port); + conn->scnt = 0; + conn->ocnt = 0; + conn->offset = 0x50; + conn->window = htons(0x0200); + conn->nullnull = 0x0000; + conn->length16 = HEADERLEN; + return conn; +} + + +/** Removes a connection from the list of connections made. + * The list of connections is necessary for buffering. + * + * @param connection The connection to delete from the tracking list. + */ +static void delete_connection(usbmux_client_t connection) +{ + usbmux_client_t *newlist = NULL; + + pthread_mutex_lock(&usbmuxmutex); + + // update the global list of connections + if (clients > 1) { + newlist = + (usbmux_client_t *) malloc(sizeof(usbmux_client_t) * + (clients - 1)); + int i = 0, j = 0; + for (i = 0; i < clients; i++) { + if (connlist[i] == connection) + continue; + else { + newlist[j] = connlist[i]; + j++; + } + } + } + if (connlist) { + free(connlist); + } + connlist = newlist; + clients--; + + // free up this connection + pthread_mutex_lock(&connection->mutex); + if (connection->recv_buffer) { + free(connection->recv_buffer); + connection->recv_buffer = NULL; + } + if (connection->header) { + free(connection->header); + connection->header = NULL; + } + connection->r_len = 0; + pthread_mutex_unlock(&connection->mutex); + pthread_mutex_destroy(&connection->mutex); + free(connection); + + pthread_mutex_unlock(&usbmuxmutex); +} + +/** Adds a connection to the list of connections made. + * The connection list is necessary for buffering. + * + * @param connection The connection to add to the global list of connections. + */ + +static void add_connection(usbmux_client_t connection) +{ + pthread_mutex_lock(&usbmuxmutex); + usbmux_client_t *newlist = + (usbmux_client_t *) realloc(connlist, + sizeof(usbmux_client_t) * (clients + + 1)); + newlist[clients] = connection; + connlist = newlist; + clients++; + pthread_mutex_unlock(&usbmuxmutex); +} + +/** + * Get a source port number that is not used by one of our connections + * This is needed for us to make sure we are not sending on another + * connection. + */ +static uint16_t get_free_port() +{ + int i; + uint16_t newport = 30000; + int cnt = 0; + + pthread_mutex_lock(&usbmuxmutex); + while (1) { + cnt = 0; + for (i = 0; i < clients; i++) { + if (ntohs(connlist[i]->header->sport) == newport) { + cnt++; + } + } + if (cnt == 0) { + // newport is not used in our list of connections! + break; + } else { + newport++; + if (newport < 30000) { + // if all ports from 30000 to 65535 are in use, + // the value wraps (16-bit overflow) + // return 0, no port is available. + // This should not happen, but just in case ;) + newport = 0; + break; + } + } + } + pthread_mutex_unlock(&usbmuxmutex); + + return newport; +} + +/** Initializes a connection to 'device' with source port s_port and destination port d_port + * + * @param device The device to initialize a connection on. + * @param src_port The source port + * @param dst_port The destination port -- 0xf27e for lockdownd. + * @param client A mux TCP header for the connection which is used for tracking and data transfer. + * @return 0 on success, a negative errno value otherwise. + */ +int usbmux_new_client(usbmux_device_t device, uint16_t src_port, + uint16_t dst_port, usbmux_client_t * client) +{ + if (!device || !dst_port) + return -EINVAL; + + src_port = get_free_port(); + + if (!src_port) { + // this is a special case, if we get 0, this is not good, so + return -EISCONN; // TODO: error code suitable? + } + // Initialize connection stuff + usbmux_client_t new_connection = + (usbmux_client_t) malloc(sizeof(struct usbmux_client_int)); + new_connection->header = new_mux_packet(src_port, dst_port); + + // send TCP syn + if (new_connection && new_connection->header) { + int err = 0; + new_connection->header->tcp_flags = TCP_SYN; + new_connection->header->length = new_connection->header->length; + new_connection->header->length16 = + new_connection->header->length16; + new_connection->header->scnt = 0; + new_connection->header->ocnt = 0; + new_connection->device = device; + new_connection->recv_buffer = NULL; + new_connection->r_len = 0; + pthread_cond_init(&new_connection->wait, NULL); + pthread_mutex_init(&new_connection->mutex, NULL); + pthread_cond_init(&new_connection->wr_wait, NULL); + new_connection->wr_pending_scnt = 0; + new_connection->wr_window = 0; + add_connection(new_connection); + new_connection->error = 0; + new_connection->cleanup = 0; + hton_header(new_connection->header); + log_debug_msg("%s: send_to_device (%d --> %d)\n", __func__, + ntohs(new_connection->header->sport), + ntohs(new_connection->header->dport)); + err = + send_to_device(device, (char *) new_connection->header, + sizeof(usbmux_tcp_header)); + if (err >= 0) { + *client = new_connection; + return 0; + } else { + delete_connection(new_connection); + return err; + } + } + // if we get to this point it's probably bad + return -ENOMEM; +} + +/** Cleans up the given USBMux connection. + * @note Once a connection is closed it may not be used again. + * + * @param connection The connection to close. + * + * @return 0 on success or a negative errno value on error. + */ +int usbmux_free_client(usbmux_client_t client) +{ + if (!client || !client->device) + return -EINVAL; + + int err = 0; + int result = 0; + pthread_mutex_lock(&client->mutex); + client->header->tcp_flags = TCP_FIN; + client->header->length = 0x1C; + client->header->window = 0; + client->header->length16 = 0x1C; + hton_header(client->header); + + err = + send_to_device(client->device, (char *) client->header, + sizeof(usbmux_tcp_header)); + if (err < 0) { + log_debug_msg("%s: error sending TCP_FIN\n", __func__); + result = err; + } + + client->cleanup = 1; + + // make sure we don't have any last-minute laggards waiting on this. + // I put it after the mutex unlock because we have cases where the + // conditional wait is dependent on re-grabbing that mutex. + pthread_cond_broadcast(&client->wait); + pthread_cond_destroy(&client->wait); + pthread_cond_broadcast(&client->wr_wait); + pthread_cond_destroy(&client->wr_wait); + + pthread_mutex_unlock(&client->mutex); + + return result; +} + +/** Sends the given data over the selected connection. + * + * @param client The client we're sending data on. + * @param data A pointer to the data to send. + * @param datalen How much data we're sending. + * @param sent_bytes The number of bytes sent, minus the header (28) + * + * @return 0 on success or a negative errno value on error. + */ +int usbmux_send(usbmux_client_t client, const char *data, uint32_t datalen, + uint32_t * sent_bytes) +{ + if (!client->device || !client || !sent_bytes) + return -EINVAL; + + if (client->error < 0) { + return client->error; + } + + *sent_bytes = 0; + pthread_mutex_lock(&client->mutex); + + int sendresult = 0; + uint32_t blocksize = 0; + if (client->wr_window <= 0) { + struct timespec ts; + clock_gettime(CLOCK_REALTIME, &ts); + //ts.tv_sec += 1; + ts.tv_nsec += 750 * 1000; + if (pthread_cond_timedwait(&client->wait, &client->mutex, &ts) == + ETIMEDOUT) { + // timed out. optimistically grow the window and try to make progress + client->wr_window += WINDOW_INCREMENT; + } + } + + blocksize = sizeof(usbmux_tcp_header) + datalen; + + // client->scnt and client->ocnt should already be in host notation... + // we don't need to change them juuuust yet. + char *buffer = (char *) malloc(blocksize + 2); // allow 2 bytes of safety padding + // Set the length + client->header->length = blocksize; + client->header->length16 = blocksize; + + // Put header into big-endian notation + hton_header(client->header); + // Concatenation of stuff in the buffer. + memcpy(buffer, client->header, sizeof(usbmux_tcp_header)); + memcpy(buffer + sizeof(usbmux_tcp_header), data, datalen); + + log_debug_msg("%s: send_to_device(%d --> %d)\n", __func__, + ntohs(client->header->sport), + ntohs(client->header->dport)); + sendresult = send_to_device(client->device, buffer, blocksize); + // Now that we've sent it off, we can clean up after our sloppy selves. + if (buffer) + free(buffer); + + // revert header fields that have been swapped before trying to send + ntoh_header(client->header); + + // update counts ONLY if the send succeeded. + if ((uint32_t) sendresult == blocksize) { + // Re-calculate scnt + client->header->scnt += datalen; + client->wr_window -= blocksize; + } + + pthread_mutex_unlock(&client->mutex); + + if (sendresult == -ETIMEDOUT || sendresult == 0) { + // no problem for now... + *sent_bytes = 0; + return -ETIMEDOUT; + } else if (sendresult < 0) { + return sendresult; + } else if ((uint32_t) sendresult == blocksize) { + // actual number of data bytes sent. + *sent_bytes = sendresult - HEADERLEN; + return 0; + } else { + fprintf(stderr, + "usbsend managed to dump a packet that is not full size. %d of %d\n", + sendresult, blocksize); + return -EBADMSG; + } +} + +/** append the packet's DATA to the receive buffer for the client. + * + * this has a few other corner-case functions: + * 1. this will properly handle the handshake syn+ack. + * 2. for all receives, this will appropriately update the ocnt. + * + * @return number of bytes consumed (header + data) + */ +uint32_t append_receive_buffer(usbmux_client_t client, char *packet) +{ + if (client == NULL || packet == NULL) + return 0; + + usbmux_tcp_header *header = (usbmux_tcp_header *) packet; + char *data = &packet[HEADERLEN]; + uint32_t packetlen = ntohl(header->length); + uint32_t datalen = packetlen - HEADERLEN; + + int dobroadcast = 0; + + pthread_mutex_lock(&client->mutex); + + // we need to handle a few corner case tasks and book-keeping which + // falls on our responsibility because we are the ones reading in + // feedback. + if (client->header->scnt == 0 && client->header->ocnt == 0) { + log_debug_msg("client is still waiting for handshake.\n"); + if (header->tcp_flags == (TCP_SYN | TCP_ACK)) { + log_debug_msg("yes, got syn+ack ; replying with ack.\n"); + client->header->tcp_flags = TCP_ACK; + client->header->length = sizeof(usbmux_tcp_header); + client->header->length16 = sizeof(usbmux_tcp_header); + client->header->scnt += 1; + client->header->ocnt = header->ocnt; + hton_header(client->header); + // push it to USB + // TODO: need to check for error in the send here.... :( + log_debug_msg("%s: send_to_device (%d --> %d)\n", __func__, + ntohs(client->header->sport), + ntohs(client->header->dport)); + if (send_to_device + (client->device, (char *) client->header, + sizeof(usbmux_tcp_header)) <= 0) { + log_debug_msg("%s: error when pushing to usb...\n", + __func__); + } + // need to revert some of the fields back to host notation. + ntoh_header(client->header); + } else { + client->error = -ECONNABORTED; + // woah... this connection failed us. + // TODO: somehow signal that this stream is a no-go. + log_debug_msg("WOAH! client failed to get proper syn+ack.\n"); + } + } + // update TCP counters and windows. + // + // save the window that we're getting from the USB device. + // apparently the window is bigger than just the 512 that's typically + // advertised. iTunes apparently shifts this value by 8 to get a much + // larger number. + if (header->tcp_flags & TCP_RST) { + client->error = -ECONNRESET; + + if (datalen > 0) { + char e_msg[128]; + e_msg[0] = 0; + if (datalen > 1) { + memcpy(e_msg, data + 1, datalen - 1); + e_msg[datalen - 1] = 0; + } + // fetch the message + switch (data[0]) { + case 0: + // this is not an error, it's just a status message. + log_debug_msg("received status message: %s\n", e_msg); + datalen = 0; + break; + case 1: + log_debug_msg("received error message: %s\n", e_msg); + datalen = 0; + break; + default: + log_debug_msg + ("received unknown message (type 0x%02x): %s\n", + data[0], e_msg); + //datalen = 0; // <-- we let this commented out for testing + break; + } + } else { + log_debug_msg + ("peer sent connection reset. setting error: %d\n", + client->error); + } + } + // the packet's ocnt tells us how much of our data the device has received. + if (header->tcp_flags & TCP_ACK) { + // this is a hacky magic number condition. it seems that once + // the window reported by the device starts to drop below this + // number, we quickly fall into connection reset problems. + // Once we see the reported window size start falling off, + // ut off and wait for solid acks to come back. + if (ntohs(header->window) < 256) + client->wr_window = 0; + + // check what just got acked. + if (ntohl(header->ocnt) < client->header->scnt) { + // we got some kind of ack, but it hasn't caught up + // with the pending that have been sent. + pthread_cond_broadcast(&client->wr_wait); + } else if (ntohl(header->ocnt) > + /*client->wr_pending_scnt */ client->header->scnt) { + fprintf(stderr, + "WTF?! acks overtook pending outstanding. %u,%u\n", + ntohl(header->ocnt), client->wr_pending_scnt); + } else { + // reset the window + client->wr_window = WINDOW_MAX; + pthread_cond_broadcast(&client->wr_wait); + } + } + // the packet's scnt will be our new ocnt. + client->header->ocnt = ntohl(header->scnt); + + // ensure there is enough space, either by first malloc or realloc + if (datalen > 0) { + log_debug_msg("%s: putting %d bytes into client's recv_buffer\n", + __func__, datalen); + if (client->r_len == 0) + dobroadcast = 1; + + if (client->recv_buffer == NULL) { + client->recv_buffer = malloc(datalen); + client->r_len = 0; + } else { + client->recv_buffer = + realloc(client->recv_buffer, client->r_len + datalen); + } + + memcpy(&client->recv_buffer[client->r_len], data, datalen); + client->r_len += datalen; + } + + pthread_mutex_unlock(&client->mutex); + + // I put this outside the mutex unlock just so that when the threads + // wake, we don't have to do another round of unlock+try to grab. + if (dobroadcast) + pthread_cond_broadcast(&client->wait); + + return packetlen; +} + +/** + * @note THERE IS NO MUTEX LOCK IN THIS FUNCTION! + * because we're only called from one location, pullbulk, where the lock + * is already held. + */ +usbmux_client_t find_client(usbmux_tcp_header * recv_header) +{ + // remember, as we're looking for the client, the receive header is + // coming from the USB into our client. This means that when we check + // the src/dst ports, we need to reverse them. + usbmux_client_t retval = NULL; + + // just for debugging check, I'm going to convert the numbers to host-endian. + uint16_t hsport = ntohs(recv_header->sport); + uint16_t hdport = ntohs(recv_header->dport); + + pthread_mutex_lock(&usbmuxmutex); + int i; + for (i = 0; i < clients; i++) { + uint16_t csport = ntohs(connlist[i]->header->sport); + uint16_t cdport = ntohs(connlist[i]->header->dport); + + if (hsport == cdport && hdport == csport) { + retval = connlist[i]; + break; + } + } + pthread_mutex_unlock(&usbmuxmutex); + + return retval; +} + +/** pull in a big USB bulk packet and distribute it to queues appropriately. + */ +int usbmux_pullbulk(usbmux_device_t device) +{ + if (!device) + return -EINVAL; + + int res = 0; + static const int DEFAULT_CAPACITY = 128 * 1024; + if (device->usbReceive.buffer == NULL) { + device->usbReceive.capacity = DEFAULT_CAPACITY; + device->usbReceive.buffer = malloc(device->usbReceive.capacity); + device->usbReceive.leftover = 0; + } + // start the cursor off just ahead of the leftover. + char *cursor = &device->usbReceive.buffer[device->usbReceive.leftover]; + // pull in content, note that the amount we can pull is capacity minus leftover + int readlen = + recv_from_device_timeout(device, cursor, + device->usbReceive.capacity - + device->usbReceive.leftover, 3000); + if (readlen < 0) { + res = readlen; + //fprintf(stderr, "recv_from_device_timeout gave us an error.\n"); + readlen = 0; + } + if (readlen > 0) { + //fprintf(stdout, "recv_from_device_timeout pulled an extra %d bytes\n", readlen); + } + // the amount of content we have to work with is the remainder plus + // what we managed to read + device->usbReceive.leftover += readlen; + + // reset the cursor to the front of that buffer and work through + // trying to decode packets out of them. + cursor = device->usbReceive.buffer; + while (1) { + // check if there's even sufficient data to decode a header + if (device->usbReceive.leftover < HEADERLEN) + break; + usbmux_tcp_header *header = (usbmux_tcp_header *) cursor; + + log_debug_msg("%s: recv_from_device_timeout (%d --> %d)\n", + __func__, ntohs(header->sport), + ntohs(header->dport)); + + // now that we have a header, check if there is sufficient data + // to construct a full packet, including its data + uint32_t packetlen = ntohl(header->length); + if ((uint32_t) device->usbReceive.leftover < packetlen) { + fprintf(stderr, + "%s: not enough data to construct a full packet\n", + __func__); + break; + } + // ok... find the client this packet will get stuffed to. + usbmux_client_t client = find_client(header); + if (client == NULL) { + log_debug_msg + ("WARNING: client for packet cannot be found. dropping packet.\n"); + } else { + // stuff the data + log_debug_msg + ("%s: found client, calling append_receive_buffer\n", + __func__); + append_receive_buffer(client, cursor); + + // perhaps this is too general, == -ECONNRESET + // might be a better check here + if (client->error < 0) { + pthread_mutex_lock(&client->mutex); + if (client->cleanup) { + pthread_mutex_unlock(&client->mutex); + log_debug_msg("freeing up connection (%d->%d)\n", + ntohs(client->header->sport), + ntohs(client->header->dport)); + delete_connection(client); + } else { + pthread_mutex_unlock(&client->mutex); + } + } + } + + // move the cursor and account for the consumption + cursor += packetlen; + device->usbReceive.leftover -= packetlen; + } + + // now, we need to manage any leftovers. + // I'm going to manage the leftovers by alloc'ing a new block and + // copyingthe leftovers to it. This is just to prevent problems with + // memory moves where there may be overlap. Besides, the leftovers + // should be small enough that this copy is minimal in overhead. + // + // if there are no leftovers, we just leave the datastructure as is, + // and re-use the block next time. + if (device->usbReceive.leftover > 0 + && cursor != device->usbReceive.buffer) { + log_debug_msg("%s: we got a leftover, so handle it\n", __func__); + char *newbuff = malloc(DEFAULT_CAPACITY); + memcpy(newbuff, cursor, device->usbReceive.leftover); + free(device->usbReceive.buffer); + device->usbReceive.buffer = newbuff; + device->usbReceive.capacity = DEFAULT_CAPACITY; + } + + return res; +} + +/** + * return the error code stored in usbmux_client_t structure, + * e.g. non-zero when an usb read error occurs. + * + * @param client the usbmux client + * + * @return 0 or a negative errno value. + */ +int usbmux_get_error(usbmux_client_t client) +{ + if (!client) { + return 0; + } + return client->error; +} + +/** This function reads from the client's recv_buffer. + * + * @param client The client to receive data from. + * @param data Where to put the data we receive. + * @param datalen How much data to read. + * @param timeout How many milliseconds to wait for data + * + * @return 0 on success or a negative errno value on failure. + */ +int usbmux_recv_timeout(usbmux_client_t client, char *data, + uint32_t datalen, uint32_t * recv_bytes, + int timeout) +{ + + if (!client || !data || datalen == 0 || !recv_bytes) + return -EINVAL; + + if (client->error < 0) + return client->error; + + pthread_mutex_lock(&client->mutex); + + if (timeout > 0 && (client->recv_buffer == NULL || client->r_len == 0)) { + struct timespec ts; + clock_gettime(CLOCK_REALTIME, &ts); + ts.tv_sec += timeout / 1000; + ts.tv_nsec += (timeout - ((int) (timeout / 1000)) * 1000) * 1000; + pthread_cond_timedwait(&client->wait, &client->mutex, &ts); + } + + *recv_bytes = 0; + if (client->recv_buffer != NULL && client->r_len > 0) { + uint32_t foolen = datalen; + if ((int) foolen > client->r_len) + foolen = client->r_len; + memcpy(data, client->recv_buffer, foolen); + *recv_bytes = foolen; + + // preserve any left-over unread amounts. + int remainder = client->r_len - foolen; + if (remainder > 0) { + char *newbuf = malloc(remainder); + memcpy(newbuf, client->recv_buffer + foolen, remainder); + client->r_len = remainder; + free(client->recv_buffer); + client->recv_buffer = newbuf; + } else { + free(client->recv_buffer); + client->recv_buffer = NULL; + client->r_len = 0; + } + } + + pthread_mutex_unlock(&client->mutex); + + return 0; +} |