Add protocol implementation for debugserver service

3 files changed, 662 insertions, 0 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 287b4e0..e45437b 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -26,6 +26,7 @@ libimobiledevice_la_SOURCES = idevice.c idevice.h \
 		       restore.c restore.h\
 		       diagnostics_relay.c diagnostics_relay.h\
 		       heartbeat.c heartbeat.h\
+		       debugserver.c debugserver.h\
 		       webinspector.c webinspector.h\
 		       syslog_relay.c syslog_relay.h
 
diff --git a/src/debugserver.c b/src/debugserver.c
new file mode 100644
index 0000000..1e38698
--- /dev/null
+++ b/src/debugserver.c
@@ -0,0 +1,620 @@
+/*
+ * debugserver.c 
+ * com.apple.debugserver service implementation.
+ * 
+ * Copyright (c) 2014 Martin Szulecki 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
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include <string.h>
+#include <stdlib.h>
+#define _GNU_SOURCE 1
+#define __USE_GNU 1
+#include <stdio.h>
+
+#include "debugserver.h"
+#include "lockdown.h"
+#include "common/debug.h"
+#include "common/utils.h"
+#include "asprintf.h"
+
+/**
+ * Convert a service_error_t value to a debugserver_error_t value.
+ * Used internally to get correct error codes.
+ *
+ * @param err An service_error_t error code
+ *
+ * @return A matching debugserver_error_t error code,
+ *     DEBUGSERVER_E_UNKNOWN_ERROR otherwise.
+ */
+static debugserver_error_t debugserver_error(service_error_t err)
+{
+	switch (err) {
+		case SERVICE_E_SUCCESS:
+			return DEBUGSERVER_E_SUCCESS;
+		case SERVICE_E_INVALID_ARG:
+			return DEBUGSERVER_E_INVALID_ARG;
+		case SERVICE_E_MUX_ERROR:
+			return DEBUGSERVER_E_MUX_ERROR;
+		case SERVICE_E_SSL_ERROR:
+			return DEBUGSERVER_E_SSL_ERROR;
+		default:
+			break;
+	}
+	return DEBUGSERVER_E_UNKNOWN_ERROR;
+}
+
+debugserver_error_t debugserver_client_new(idevice_t device, lockdownd_service_descriptor_t service, debugserver_client_t* client)
+{
+	*client = NULL;
+
+	if (!device || !service || service->port == 0 || !client || *client) {
+		debug_info("Incorrect parameter passed to debugserver_client_new.");
+		return DEBUGSERVER_E_INVALID_ARG;
+	}
+
+	debug_info("Creating debugserver_client, port = %d.", service->port);
+
+	service_client_t parent = NULL;
+	debugserver_error_t ret = debugserver_error(service_client_new(device, service, &parent));
+	if (ret != DEBUGSERVER_E_SUCCESS) {
+		debug_info("Creating base service client failed. Error: %i", ret);
+		return ret;
+	}
+
+	debugserver_client_t client_loc = (debugserver_client_t) malloc(sizeof(struct debugserver_client_private));
+	client_loc->parent = parent;
+	client_loc->noack_mode = 0;
+
+	*client = client_loc;
+
+	debug_info("debugserver_client successfully created.");
+	return 0;
+}
+
+debugserver_error_t debugserver_client_start_service(idevice_t device, debugserver_client_t * client, const char* label)
+{
+	debugserver_error_t err = DEBUGSERVER_E_UNKNOWN_ERROR;
+	service_client_factory_start_service(device, DEBUGSERVER_SERVICE_NAME, (void**)client, label, SERVICE_CONSTRUCTOR(debugserver_client_new), &err);
+	return err;
+}
+
+debugserver_error_t debugserver_client_free(debugserver_client_t client)
+{
+	if (!client)
+		return DEBUGSERVER_E_INVALID_ARG;
+
+	debugserver_error_t err = debugserver_error(service_client_free(client->parent));
+	client->parent = NULL;
+	free(client);
+
+	return err;
+}
+
+debugserver_error_t debugserver_client_send(debugserver_client_t client, const char* data, uint32_t size, uint32_t *sent)
+{
+	debugserver_error_t res = DEBUGSERVER_E_UNKNOWN_ERROR;
+	int bytes = 0;
+
+	if (!client || !data || (size == 0)) {
+		return SERVICE_E_INVALID_ARG;
+	}
+
+	debug_info("sending %d bytes", size);
+	res = debugserver_error(service_send(client->parent, data, size, (uint32_t*)&bytes));
+	if (bytes <= 0) {
+		debug_info("ERROR: sending to device failed.");
+	}
+	if (sent) {
+		*sent = (uint32_t)bytes;
+	}
+
+	return res;
+}
+
+debugserver_error_t debugserver_client_receive_with_timeout(debugserver_client_t client, char* data, uint32_t size, uint32_t *received, unsigned int timeout)
+{
+	debugserver_error_t res = DEBUGSERVER_E_UNKNOWN_ERROR;
+	int bytes = 0;
+
+	if (!client || !data || (size == 0)) {
+		return DEBUGSERVER_E_INVALID_ARG;
+	}
+
+	res = debugserver_error(service_receive_with_timeout(client->parent, data, size, (uint32_t*)&bytes, timeout));
+	if (bytes <= 0) {
+		debug_info("Could not read data, error %d", res);
+	}
+	if (received) {
+		*received = (uint32_t)bytes;
+	}
+
+	return res;
+}
+
+debugserver_error_t debugserver_client_receive(debugserver_client_t client, char* data, uint32_t size, uint32_t *received)
+{
+	return debugserver_client_receive_with_timeout(client, data, size, received, 1000);
+}
+
+debugserver_error_t debugserver_command_new(const char* name, int argc, const char* argv[], debugserver_command_t* command)
+{
+	int i;
+	debugserver_command_t tmp = (debugserver_command_t) malloc(sizeof(struct debugserver_command_private));
+
+	/* copy name */
+	tmp->name = strdup(name);
+
+	/* copy arguments */
+	tmp->argc = argc;
+	tmp->argv = NULL;
+	if (argc > 0) {
+		tmp->argv = malloc(sizeof(char*) * (argc + 2));
+		for (i = 0; i < argc; i++) {
+			tmp->argv[i] = strdup(argv[i]);
+		}
+		tmp->argv[i+1] = NULL;
+	}
+
+	/* return */
+	*command = tmp;
+
+	return DEBUGSERVER_E_SUCCESS;
+}
+
+debugserver_error_t debugserver_command_free(debugserver_command_t command)
+{
+	int i;
+	debugserver_error_t res = DEBUGSERVER_E_UNKNOWN_ERROR;
+
+	if (!command)
+		return DEBUGSERVER_E_INVALID_ARG;
+
+	if (command) {
+		if (command->name)
+			free(command->name);
+		if (command->argv && command->argc) {
+			for (i = 0; i < command->argc; i++) {
+				free(command->argv[i]);
+			}
+			free(command->argv);
+		}
+		free(command);
+		res = DEBUGSERVER_E_SUCCESS;
+	}
+
+	return res;
+}
+
+static int debugserver_hex2int(char c)
+{
+	if (c >= '0' && c <= '9')
+		return c - '0';
+	else if (c >= 'a' && c <= 'f')
+		return 10 + c - 'a';
+	else if (c >= 'A' && c <= 'F')
+		return 10 + c - 'A';
+	else
+		return c;
+}
+
+static char debugserver_int2hex(int x)
+{
+	const char *hexchars = "0123456789ABCDEF";
+	return hexchars[x];
+}
+
+#define DEBUGSERVER_HEX_ENCODE_FIRST_BYTE(byte) debugserver_int2hex((byte >> 0x4) & 0xf)
+#define DEBUGSERVER_HEX_ENCODE_SECOND_BYTE(byte) debugserver_int2hex(byte & 0xf)
+#define DEBUGSERVER_HEX_DECODE_FIRST_BYTE(byte) ((byte >> 0x4) & 0xf)
+#define DEBUGSERVER_HEX_DECODE_SECOND_BYTE(byte) (byte & 0xf)
+
+static uint32_t debugserver_get_checksum_for_buffer(const char* buffer, uint32_t size)
+{
+	uint32_t checksum = 0;
+	uint32_t i;
+
+	for (i = 0; i < size; i++) {
+		checksum += buffer[i];
+	}
+
+	return checksum;
+}
+
+static int debugserver_response_is_checksum_valid(const char* response, uint32_t size)
+{
+	uint32_t checksum = 0;
+	if ((size - DEBUGSERVER_CHECKSUM_HASH_LENGTH - 1) > 0)
+		checksum = debugserver_get_checksum_for_buffer(&response[1], size - DEBUGSERVER_CHECKSUM_HASH_LENGTH - 1);
+
+	debug_info("checksum: 0x%x", checksum);
+
+	if ((unsigned)debugserver_hex2int(response[size - 2]) != DEBUGSERVER_HEX_DECODE_FIRST_BYTE(checksum))
+		return 0;
+
+	if ((unsigned)debugserver_hex2int(response[size - 1]) != DEBUGSERVER_HEX_DECODE_SECOND_BYTE(checksum))
+		return 0;
+
+	debug_info("valid checksum");
+
+	return 1;
+}
+
+void debugserver_encode_string(const char* buffer, char** encoded_buffer, uint32_t* encoded_length)
+{
+	uint32_t position;
+	uint32_t index;
+	uint32_t length = strlen(buffer);
+	*encoded_length = (2 * length) + DEBUGSERVER_CHECKSUM_HASH_LENGTH + 1;
+
+	*encoded_buffer = malloc(sizeof(char) * (*encoded_length));
+	memset(*encoded_buffer, '\0', *encoded_length);
+	for (position = 0, index = 0; index < length; index++) {
+		position = (index * (2 * sizeof(char)));
+		(*encoded_buffer)[position] = DEBUGSERVER_HEX_ENCODE_FIRST_BYTE(buffer[index]);
+		(*encoded_buffer)[position + 1] = DEBUGSERVER_HEX_ENCODE_SECOND_BYTE(buffer[index]);
+	}
+}
+
+void debugserver_decode_string(const char *encoded_buffer, size_t encoded_length, char** buffer)
+{
+	*buffer = malloc(sizeof(char) * ((encoded_length / 2)+1));
+	char* t = *buffer;
+	const char *f = encoded_buffer;
+	const char *fend = f + encoded_length;
+	while (f < fend) {
+		*t++ = debugserver_hex2int(*f) << 4 | debugserver_hex2int(f[1]);
+		f += 2;
+	}
+	*t = '\0';
+}
+
+static void debugserver_format_command(const char* prefix, const char* command, const char* arguments, int calculate_checksum, char** buffer, uint32_t* size)
+{
+	char checksum_hash[DEBUGSERVER_CHECKSUM_HASH_LENGTH + 1] = {'#', '0', '0', '\0'};
+	char* encoded = NULL;
+	uint32_t encoded_length = 0;
+
+	if (arguments) {
+		/* arguments must be hex encoded */
+		debugserver_encode_string(arguments, &encoded, &encoded_length);
+	} else {
+		encoded = NULL;
+	}
+
+	char* encoded_command = string_concat(command, encoded, NULL);
+	encoded_length = strlen(encoded_command);
+
+	if (calculate_checksum) {
+		uint32_t checksum = debugserver_get_checksum_for_buffer(encoded_command, encoded_length);
+		checksum_hash[1] = DEBUGSERVER_HEX_ENCODE_FIRST_BYTE(checksum);
+		checksum_hash[2] = DEBUGSERVER_HEX_ENCODE_SECOND_BYTE(checksum);
+	}
+
+	*buffer = string_concat(prefix, encoded_command, checksum_hash, NULL);
+	*size = strlen(prefix) + strlen(encoded_command) + DEBUGSERVER_CHECKSUM_HASH_LENGTH;
+
+	debug_info("formatted command: %s size: %d checksum: 0x%s", *buffer, *size, checksum_hash);
+
+	if (encoded_command)
+		free(encoded_command);
+
+	if (encoded)
+		free(encoded);
+}
+
+static debugserver_error_t debugserver_client_send_ack(debugserver_client_t client)
+{
+	debug_info("sending ACK");
+	return debugserver_client_send(client, "+", sizeof(char), NULL);
+}
+
+static debugserver_error_t debugserver_client_send_noack(debugserver_client_t client)
+{
+	debug_info("sending !ACK");
+	return debugserver_client_send(client, "-", sizeof(char), NULL);
+}
+
+static debugserver_error_t debugserver_client_set_ack_mode(debugserver_client_t client, int enabled)
+{
+	if (!client)
+		return DEBUGSERVER_E_INVALID_ARG;
+
+	client->noack_mode = (enabled == 0)? 1: 0;
+
+	debug_info("ack mode: %s", client->noack_mode == 0 ? "on": "off");
+
+	return DEBUGSERVER_E_SUCCESS;
+}
+
+static int debugserver_client_receive_internal_check(debugserver_client_t client, char* received_char)
+{
+	debugserver_error_t res = DEBUGSERVER_E_SUCCESS;
+	int did_receive_char = 0;
+	char buffer = 0;
+	uint32_t bytes = 0;
+
+	/* we loop here as we expect an answer */
+	res = debugserver_client_receive_with_timeout(client, &buffer, sizeof(char), &bytes, 1000);
+	if (res == DEBUGSERVER_E_SUCCESS && received_char[0] != 0) {
+		if (memcmp(&buffer, received_char, sizeof(char)) == 0) {
+			did_receive_char = 1;
+		}
+	} else {
+		did_receive_char = 0;
+	}
+
+	if (!did_receive_char) {
+		memcpy(received_char, &buffer, sizeof(char));
+	}
+
+	return did_receive_char;
+}
+
+debugserver_error_t debugserver_client_receive_response(debugserver_client_t client, char** response)
+{
+	debugserver_error_t res = DEBUGSERVER_E_SUCCESS;
+
+	int should_receive = 1;
+	int skip_prefix = 0;
+	char* command_prefix = strdup("$");
+
+	char* buffer = NULL;
+	uint32_t buffer_size = 0;
+
+	if (response)
+		*response = NULL;
+
+	if (!client->noack_mode) {
+		char ack[2] = {'+', '\0'};
+		debug_info("attempting to receive ACK %c", *ack);
+		should_receive = debugserver_client_receive_internal_check(client, ack);
+		debug_info("received char: %c", *ack);
+		if (strncmp(ack, command_prefix, sizeof(char)) == 0) {
+			should_receive = 1;
+			skip_prefix = 1;
+			buffer = strdup(command_prefix);
+			buffer_size += sizeof(char);
+			debug_info("received ACK");
+		}
+	}
+
+	debug_info("should_receive: %d, skip_prefix: %d", should_receive, skip_prefix);
+
+	if (should_receive && !skip_prefix) {
+		debug_info("attempting to receive prefix");
+		should_receive = debugserver_client_receive_internal_check(client, command_prefix);
+		debug_info("received command_prefix: %c", *command_prefix);
+		if (should_receive) {
+			if (buffer) {
+				memcpy(buffer, command_prefix, sizeof(char));
+			} else {
+				buffer = strdup(command_prefix);
+				buffer_size += sizeof(char);
+			}
+		}
+	}
+
+	debug_info("buffer: %*s, should_receive: %d, skip_prefix: %d", buffer_size, buffer, should_receive, skip_prefix);
+
+	if (should_receive) {
+		uint32_t checksum_length = DEBUGSERVER_CHECKSUM_HASH_LENGTH;
+		int receiving_checksum_response = 0;
+		debug_info("attempting to read up response until checksum");
+		while ((checksum_length > 0)) {
+			char data[2] = {'#', '\0'};
+			if (debugserver_client_receive_internal_check(client, data)) {
+				receiving_checksum_response = 1;
+			}
+			if (receiving_checksum_response) {
+				checksum_length--;
+			}
+			char* newbuffer = string_concat(buffer, data, NULL);
+			buffer_size += sizeof(char);
+			free(buffer);
+			buffer = NULL;
+			buffer = newbuffer;
+			newbuffer = NULL;
+		}
+		debug_info("validating response checksum...");
+		int valid_response = debugserver_response_is_checksum_valid(buffer, buffer_size);
+		if (valid_response) {
+			if (response) {
+				/* assemble response string */
+				uint32_t response_size = sizeof(char) * (buffer_size - DEBUGSERVER_CHECKSUM_HASH_LENGTH - 1);
+				*response = (char*)malloc(response_size + 1);
+				memcpy(*response, buffer + 1, response_size);
+				(*response)[response_size] = '\0';
+			}
+			if (!client->noack_mode) {
+				/* confirm valid command */
+				debugserver_client_send_ack(client);
+			}
+		} else {
+			/* response was invalid */
+			res = DEBUGSERVER_E_RESPONSE_ERROR;
+			if (!client->noack_mode) {
+				/* report invalid command */
+				debugserver_client_send_noack(client);
+			}
+		}
+	}
+
+	if (response)
+		debug_info("response: %s", *response);
+
+	if (buffer)
+		free(buffer);
+
+	if (command_prefix)
+		free(command_prefix);
+
+	return res;
+}
+
+debugserver_error_t debugserver_client_send_command(debugserver_client_t client, debugserver_command_t command, char** response)
+{
+	debugserver_error_t res = DEBUGSERVER_E_SUCCESS;
+	int i;
+	uint32_t bytes = 0;
+
+	char* send_buffer = NULL;
+	uint32_t send_buffer_size = 0;
+
+	char* command_arguments = NULL;
+
+	/* concat all arguments */
+	char* tmp = NULL;
+	char* newtmp = NULL;
+	for (i = 0; i < command->argc; i++) {
+		debug_info("argv[%d]: %s", i, command->argv[i]);
+		if (!tmp) {
+			tmp = strdup(command->argv[i]);
+		} else {
+			newtmp = string_concat(tmp, command->argv[i], NULL);
+			free(tmp);
+			tmp = newtmp;
+		}
+	}
+	command_arguments = tmp;
+	tmp = NULL;
+
+	debug_info("command_arguments(%d): %s", command->argc, command_arguments);
+
+	/* encode command arguments, add checksum if required and assemble entire command */
+	debugserver_format_command("$", command->name, command_arguments, !client->noack_mode, &send_buffer, &send_buffer_size);
+
+	debug_info("sending encoded command: %s", send_buffer);
+
+	res = debugserver_client_send(client, send_buffer, send_buffer_size, &bytes);
+	debug_info("command result: %d", res);
+	if (res != DEBUGSERVER_E_SUCCESS) {
+		goto cleanup;
+	}
+
+	/* receive response */
+	res = debugserver_client_receive_response(client, response);
+	debug_info("response result: %d", res);
+	if (res != DEBUGSERVER_E_SUCCESS) {
+		goto cleanup;
+	}
+
+	if (response)
+		debug_info("received response: %s", *response);
+
+	/* disable sending ack on the client */
+	if (!strncmp(command->name, "QStartNoAckMode", 16)) {
+		debugserver_client_set_ack_mode(client, 0);
+	}
+
+cleanup:
+	if (command_arguments)
+		free(command_arguments);
+
+	if (send_buffer)
+		free(send_buffer);
+
+	return res;
+}
+
+debugserver_error_t debugserver_client_set_environment_hex_encoded(debugserver_client_t client, const char* env, char** response)
+{
+	if (!client || !env)
+		return DEBUGSERVER_E_INVALID_ARG;
+
+	debugserver_error_t result = DEBUGSERVER_E_UNKNOWN_ERROR;
+	const char* env_arg[] = { env, NULL };
+
+	debugserver_command_t command = NULL;
+	debugserver_command_new("QEnvironmentHexEncoded:", 1, env_arg, &command);
+	result = debugserver_client_send_command(client, command, response);
+	debugserver_command_free(command);
+
+	return result;
+}
+
+debugserver_error_t debugserver_client_set_argv(debugserver_client_t client, int argc, char* argv[], char** response)
+{
+	if (!client || !argc)
+		return DEBUGSERVER_E_INVALID_ARG;
+
+	debugserver_error_t result = DEBUGSERVER_E_UNKNOWN_ERROR;
+	char *pkt = NULL;
+	int pkt_len = 0;
+	int i = 0;
+
+	/* calculate total length */
+	while (i < argc && argv && argv[i]) {
+		char *prefix = NULL;
+		asprintf(&prefix, ",%d,%d,", (int)strlen(argv[i]) * 2, i);
+		pkt_len += (int)strlen(prefix) + (int)strlen(argv[i]) * 2;
+		free(prefix);
+		i++;
+	}
+
+	/* allocate packet and initialize it */
+	pkt = (char *) malloc(pkt_len + 1);
+	memset(pkt, 0, pkt_len + 1);
+
+	char *pktp = pkt;
+
+	i = 0;
+	while (i < argc && argv && argv[i]) {
+		debug_info("argv[%d] = \"%s\"", i, argv[i]);
+
+		char *prefix = NULL;
+		char *m = NULL;
+		int arg_len = strlen(argv[i]);
+		int arg_hexlen = arg_len * 2;
+
+		asprintf(&prefix, ",%d,%d,", arg_hexlen, i);
+
+		m = (char *) malloc(arg_hexlen);
+		char *p = m;
+		char *q = (char*)argv[i];
+		while (*q) {
+			*p++ = debugserver_int2hex(*q >> 4);
+			*p++ = debugserver_int2hex(*q & 0xf);
+			q++;
+		}
+
+		memcpy(pktp, prefix, strlen(prefix));
+		pktp += strlen(prefix);
+
+		memcpy(pktp, m, arg_hexlen);
+		pktp += arg_hexlen;
+
+		free(prefix);
+		free(m);
+
+		i++;
+	}
+
+	pkt[0] = 'A';
+
+	debugserver_command_t command = NULL;
+	debugserver_command_new(pkt, 0, NULL, &command);
+	result = debugserver_client_send_command(client, command, response);
+	debugserver_command_free(command);
+
+	if (pkt)
+		free(pkt);
+
+	return result;
+}
diff --git a/src/debugserver.h b/src/debugserver.h
new file mode 100644
index 0000000..8608167
--- /dev/null
+++ b/src/debugserver.h
@@ -0,0 +1,41 @@
+/*
+ * debugserver.h
+ * com.apple.debugserver service header file.
+ * 
+ * Copyright (c) 2014 Martin Szulecki 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 
+ */
+
+#ifndef _DEBUGSERVER_H
+#define _DEBUGSERVER_H
+
+#include "libimobiledevice/debugserver.h"
+#include "service.h"
+
+#define DEBUGSERVER_CHECKSUM_HASH_LENGTH 0x3
+
+struct debugserver_client_private {
+	service_client_t parent;
+	int noack_mode;
+};
+
+struct debugserver_command_private {
+	char* name;
+	int argc;
+	char** argv;
+};
+
+#endif