ActiveSync應用層程式協議分析-RAPI的握手過程
ActiveSync應用層程式協議分析-RAPI的握手過程
轉載時請註明出處和作者聯絡方式作者聯絡方式：李先靜 <xianjimli at hotmail dot com>
ActiveSync與Window Mobile之間的通訊協議並不複雜，在RNDIS+USBNET之上執行TCP/IP，而TCP/IP之上的應用層協議包括RAPI和RRAC兩個協議。前段時間我完成RAPI和RRAC協議的PC端和裝置端的實現，在這個系列之中，我們將對它們的原理和實現進行分析，供要做類似工作的朋友參考。本文介紹一下RAPI的握手過程。
PC端的ActiveSync監聽990埠，同步時裝置連線到這個埠，然後開始握手：
1.裝置端傳送四個位元組的資料(0x00)表示請求握手。
2.PC端迴應四個位元組的資料(0x03)表示接受握手,並要求裝置提供裝置資訊。
3.裝置迴應四個位元組的資料(0x04)表示要上傳裝置資訊，並在其後緊跟裝置資訊。
4.PC端讀取裝置資訊，如果不要求論證，握手到此結束(要求握手的情況目前還不清楚)。
裝置資訊結構如下：
typedef struct _RapiDeviceInfo
{
RapiDeviceGuidguid;
unsigned int os_version_major;
unsigned int os_version_minor;
WStr*name;
unsigned int dev_version;
unsigned int cpu_type;
unsigned int dev_magic;
unsigned int current_partner;
unsigned int dev_id;
char*platform;
char*model;
unsigned int components_nr;
RapiComponent* components;
unsigned int pw_key;
}RapiDeviceInfo;
這個資料包前面四個位元組是這個結構的資料長度，後面的資料並不是直接按結構記憶體佈局對映過來的，而是有專門編碼方式。主要特殊之外在於，所有整數都是以小端格式存放，
PC端的程式碼類似於：
static AsmRet rapi_host_connection_device_handle_hand_shake(AsmConnection* thiz)
{
AsmRet ret = ASM_RET_FAIL;
asm_return_val_if_fail(thiz != NULL, ASM_RET_FAIL);
PrivInfo* priv = (PrivInfo*)thiz->priv;
asm_return_val_if_fail(priv->stream != NULL, ASM_RET_OK);
int length = 0;
unsigned int cmd = 0;
unsigned int resp = 0;
AsmInputBuffer* input = NULL;
do
{
ret = asm_stream_read(priv->stream, &cmd, sizeof(cmd), &length);
if(ret != ASM_RET_OK || cmd != RAPI_COMMAND_HAND_SHAKE) break;
resp = RAPI_RESP_HAND_SHAKE;
ret = asm_stream_write(priv->stream, &resp, sizeof(resp), &length);
if(ret != ASM_RET_OK) break;
ret = asm_stream_read(priv->stream, &cmd, sizeof(cmd), &length);
if(ret != ASM_RET_OK || cmd != RAPI_RESP_GET_INFO) break;
input = asm_input_buffer_create(NULL, 0, ASM_ENDIAN_LITTLE, NULL);
ret = rapi_stream_read(priv->stream, input);
if(ret != ASM_RET_OK) break;
ret = rapi_host_connection_device_parse_device_info(thiz, input);
}while(0);
if(ret != ASM_RET_OK)
{
asm_stream_destroy(priv->stream);
priv->stream = NULL;
printf("%s:%d hand shake failed./n", __func__, __LINE__);
}
asm_input_buffer_destroy(input);
return ASM_RET_OK;
}
裝置端的程式碼類似於：
static AsmRet rapi_device_connection_device_hand_shake(AsmConnection* thiz)
{
AsmRet ret = ASM_RET_FAIL;
asm_return_val_if_fail(thiz != NULL, ret);
PrivInfo* priv = (PrivInfo*)thiz->priv;
RapiDeviceInfo info = {0};
size_t length = 0;
unsigned int cmd = 0;
unsigned int resp = 0;
asm_output_buffer_reset(priv->output);
cmd = uint32_to_endian(RAPI_COMMAND_HAND_SHAKE, ASM_ENDIAN_LITTLE);
ret = asm_stream_write(priv->stream, &cmd, sizeof(cmd), &length);
assert(length == sizeof(cmd));
ret = asm_stream_read(priv->stream, &resp, sizeof(resp), &length);
assert(length == sizeof(resp));
assert(resp == RAPI_RESP_HAND_SHAKE);
cmd = uint32_to_endian(RAPI_RESP_GET_INFO, ASM_ENDIAN_LITTLE);
ret = asm_stream_write(priv->stream, &cmd, sizeof(cmd), &length);
assert(length == sizeof(cmd));
if(rapi_device_get_info(priv->device, &info) == ASM_RET_OK)
{
if(rapi_buffer_write_info(priv->output, &info) == ASM_RET_OK)
{
ret = rapi_stream_write(priv->stream, priv->output);
}
}
return ret;
}
~~end~~