開發(fā)了一款微信小游戲《約戰(zhàn)24點(diǎn)》 服務(wù)器是用 C++ 寫的，與客戶端之間采用的是 websocket 協(xié)議通信穆桂。C++ 中使用 websocket 需要對(duì)協(xié)議數(shù)據(jù)進(jìn)行處理才能使用。
1. websocket 協(xié)議數(shù)據(jù)格式詳解
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-------+-+-------------+-------------------------------+
|F|R|R|R| opcode|M| Payload len | Extended payload length |
|I|S|S|S| (4) |A| (7) | (16/64) |
|N|V|V|V| |S| | (if payload len==126/127) |
| |1|2|3| |K| | |
+-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +
| Extended payload length continued, if payload len == 127 |
+ - - - - - - - - - - - - - - - +-------------------------------+
| |Masking-key, if MASK set to 1 |
+-------------------------------+-------------------------------+
| Masking-key (continued) | Payload Data |
+-------------------------------- - - - - - - - - - - - - - - - +
: Payload Data continued ... :
+ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
| Payload Data continued ... |
+---------------------------------------------------------------+
?FIN
標(biāo)識(shí)是否為此消息的最后一個(gè)數(shù)據(jù)包，占1bit
?RSV1, RSV2, RSV3: 用于擴(kuò)展協(xié)議捣域，一般為0逾条，各占1bit
?Opcode
數(shù)據(jù)包類型（frame type）琢岩，占4bits
0x0：標(biāo)識(shí)一個(gè)中間數(shù)據(jù)包
0x1：標(biāo)識(shí)一個(gè)text類型數(shù)據(jù)包
0x2：標(biāo)識(shí)一個(gè)binary類型數(shù)據(jù)包
0x3-7：保留
0x8：標(biāo)識(shí)一個(gè)斷開連接類型數(shù)據(jù)包
0x9：標(biāo)識(shí)一個(gè)ping類型數(shù)據(jù)包
0xA：表示一個(gè)pong類型數(shù)據(jù)包
0xB-F：保留
?MASK：占1bits
用于標(biāo)識(shí)PayloadData是否經(jīng)過(guò)掩碼處理。如果是1师脂，Masking-key域的數(shù)據(jù)即是掩碼密鑰担孔，用于解碼PayloadData〕跃客戶端發(fā)出的數(shù)據(jù)幀需要進(jìn)行掩碼處理糕篇，所以此位是1。
?Payload length
Payload data的長(zhǎng)度酌心，占7bits拌消，7+16bits，7+64bits：
如果其值在0-125安券，則是payload的真實(shí)長(zhǎng)度墩崩。
如果值是126，則后面2個(gè)字節(jié)形成的16bits無(wú)符號(hào)整型數(shù)的值是payload的真實(shí)長(zhǎng)度完疫。注意泰鸡，網(wǎng)絡(luò)字節(jié)序，需要轉(zhuǎn)換壳鹤。
如果值是127盛龄，則后面8個(gè)字節(jié)形成的64bits無(wú)符號(hào)整型數(shù)的值是payload的真實(shí)長(zhǎng)度。注意，網(wǎng)絡(luò)字節(jié)序余舶，需要轉(zhuǎn)換啊鸭。
這里的長(zhǎng)度表示遵循一個(gè)原則，用最少的字節(jié)表示長(zhǎng)度（盡量減少不必要的傳輸）匿值。舉例說(shuō)赠制，payload真實(shí)長(zhǎng)度是124，在0-125之間挟憔，必須用前7位表示钟些；不允許長(zhǎng)度1是126或127，然后長(zhǎng)度2是124绊谭，這樣違反原則政恍。
?Payload data
應(yīng)用層數(shù)據(jù)
---------------------server解析client端的數(shù)據(jù)---------------------------
接收到客戶端數(shù)據(jù)后的解析規(guī)則如下：
?1byte
?1bit: frame-fin，x0表示該message后續(xù)還有frame达传；x1表示是message的最后一個(gè)frame
?3bit: 分別是frame-rsv1篙耗、frame-rsv2和frame-rsv3，通常都是x0
?4bit: frame-opcode宪赶，x0表示是延續(xù)frame宗弯；x1表示文本frame；x2表示二進(jìn)制frame搂妻；x3-7保留給非控制frame蒙保；x8表示關(guān) 閉連接；x9表示ping叽讳；xA表示pong追他；xB-F保留給控制frame
?2byte
?1bit: Mask，1表示該frame包含掩碼岛蚤；0表示無(wú)掩碼
?7bit邑狸、7bit+2byte、7bit+8byte: 7bit取整數(shù)值涤妒，若在0-125之間单雾，則是負(fù)載數(shù)據(jù)長(zhǎng)度；若是126表示她紫，后兩個(gè)byte取無(wú)符號(hào)16位整數(shù)值硅堆，是負(fù)載長(zhǎng)度；127表示后8個(gè) byte贿讹，取64位無(wú)符號(hào)整數(shù)值渐逃，是負(fù)載長(zhǎng)度
?3-6byte: 這里假定負(fù)載長(zhǎng)度在0-125之間，并且Mask為1民褂，則這4個(gè)byte是掩碼
?7-end byte: 長(zhǎng)度是上面取出的負(fù)載長(zhǎng)度茄菊，包括擴(kuò)展數(shù)據(jù)和應(yīng)用數(shù)據(jù)兩部分疯潭，通常沒有擴(kuò)展數(shù)據(jù)；若Mask為1面殖，則此數(shù)據(jù)需要解碼竖哩，解碼規(guī)則為1 -4byte掩碼循環(huán)和數(shù)據(jù)byte做異或操作。
2. C++對(duì) websocket 封裝處理
WebSocket.h
//
// Description: WebSocket RFC6544 codec, written in C++.
//
#ifndef PROJECT_WEBSOCKET_H
#define PROJECT_WEBSOCKET_H
#include <string>
#include <vector>
enum WSFrameType {
ERROR_FRAME=0xFF00,
INCOMPLETE_FRAME=0xFE00,
OPENING_FRAME=0x3300,
CLOSING_FRAME=0x3400,
INCOMPLETE_TEXT_FRAME=0x01,
INCOMPLETE_BINARY_FRAME=0x02,
TEXT_FRAME=0x81,
BINARY_FRAME=0x82,
PING_FRAME=0x19,
PONG_FRAME=0x1A
};
enum WSStatus
{
WS_STATUS_UNCONNECT = 1,
WS_STATUS_CONNECT = 2,
};
class WebSocket
{
public:
WebSocket();
//解析 WebSocket 的握手?jǐn)?shù)據(jù)
bool parseHandshake(const std::string& request);
//應(yīng)答 WebSocket 的握手
std::string respondHandshake();
//解析 WebSocket 的協(xié)議具體數(shù)據(jù)脊僚，客戶端-->服務(wù)器
int getWSFrameData(char* msg, int msgLen, std::vector<char>& outBuf, int* outLen);
//封裝 WebSocket 協(xié)議的數(shù)據(jù)相叁，服務(wù)器-->客戶端
int makeWSFrameData(char* msg, int msgLen, std::vector<char>& outBuf);
//封裝 WebSocket 協(xié)議的數(shù)據(jù)頭（二進(jìn)制數(shù)據(jù)）
static int makeWSFrameDataHeader(int len, std::vector<char>& header);
private:
std::string websocketKey_;//握手中客戶端發(fā)來(lái)的key
};
#endif //PROJECT_WEBSOCKET_H
2. WebSocket.cpp
#include "WebSocket.h"
#include "BaseFunc.h"
#include <openssl/sha.h> //for SHA1
#include <arpa/inet.h> //for ntohl
#include <string.h>
WebSocket::WebSocket()
{
}
bool WebSocket::parseHandshake(const std::string& request)
{
// 解析WEBSOCKET請(qǐng)求頭信息
bool ret = false;
std::istringstream stream(request.c_str());
std::string reqType;
std::getline(stream, reqType);
if (reqType.substr(0, 4) != "GET ")
return ret;
std::string header;
std::string::size_type pos = 0;
while (std::getline(stream, header) && header != "\r")
{
header.erase(header.end() - 1);
pos = header.find(": ", 0);
if (pos != std::string::npos)
{
std::string key = header.substr(0, pos);
std::string value = header.substr(pos + 2);
if (key == "Sec-WebSocket-Key")
{
ret = true;
websocketKey_ = value;
break;
}
}
}
return ret;
}
std::string WebSocket::respondHandshake()
{
// 算出WEBSOCKET響應(yīng)信息
std::string response = "HTTP/1.1 101 Switching Protocols\r\n";
response += "Upgrade: websocket\r\n";
response += "Connection: upgrade\r\n";
response += "Sec-WebSocket-Accept: ";
//使用請(qǐng)求傳過(guò)來(lái)的KEY+協(xié)議字符串，先用SHA1加密然后使用base64編碼算出一個(gè)應(yīng)答的KEY
const std::string magicKey("258EAFA5-E914-47DA-95CA-C5AB0DC85B11");
std::string serverKey = websocketKey_ + magicKey;
//LOG_INFO << "serverKey:" << serverKey;
//SHA1
unsigned char digest[SHA_DIGEST_LENGTH];
SHA1((unsigned char*)serverKey.c_str(), serverKey.length(), (unsigned char*)&digest);
//printf("DIGEST:"); for(int i=0; i<20; i++) printf("%02x ",digest[i]); printf("\n");
//Base64
char basestr[1024] = {0};
base64_encode((char*)digest, SHA_DIGEST_LENGTH, basestr);
//完整的握手應(yīng)答
response = response + std::string(basestr) + "\r\n";
//LOG_INFO << "RESPONSE:" << response;
return response;
}
int WebSocket::getWSFrameData(char* msg, int msgLen, std::vector<char>& outBuf, int* outLen)
{
if(msgLen < 2)
return INCOMPLETE_FRAME;
uint8_t fin_ = 0;
uint8_t opcode_ = 0;
uint8_t mask_ = 0;
uint8_t masking_key_[4] = {0,0,0,0};
uint64_t payload_length_ = 0;
int pos = 0;
//FIN
fin_ = (unsigned char)msg[pos] >> 7;
//Opcode
opcode_ = msg[pos] & 0x0f;
pos++;
//MASK
mask_ = (unsigned char)msg[pos] >> 7;
//Payload length
payload_length_ = msg[pos] & 0x7f;
pos++;
if(payload_length_ == 126)
{
uint16_t length = 0;
memcpy(&length, msg + pos, 2);
pos += 2;
payload_length_ = ntohs(length);
}
else if(payload_length_ == 127)
{
uint32_t length = 0;
memcpy(&length, msg + pos, 4);
pos += 4;
payload_length_ = ntohl(length);
}
//Masking-key
if(mask_ == 1)
{
for(int i = 0; i < 4; i++)
masking_key_[i] = msg[pos + i];
pos += 4;
}
//取出消息數(shù)據(jù)
if (msgLen >= pos + payload_length_ )
{
//Payload data
*outLen = pos + payload_length_;
outBuf.clear();
if(mask_ != 1)
{
char* dataBegin = msg + pos;
outBuf.insert(outBuf.begin(), dataBegin, dataBegin+payload_length_);
}
else
{
for(uint i = 0; i < payload_length_; i++)
{
int j = i % 4;
outBuf.push_back(msg[pos + i] ^ masking_key_[j]);
}
}
}
else
{
return INCOMPLETE_FRAME;
}
// printf("WEBSOCKET PROTOCOL\n"
// "FIN: %d\n"
// "OPCODE: %d\n"
// "MASK: %d\n"
// "PAYLOADLEN: %d\n"
// "outLen:%d\n",
// fin_, opcode_, mask_, payload_length_, *outLen);
//斷開連接類型數(shù)據(jù)包
if ((int)opcode_ == 0x8)
return -1;
return 0;
}
int WebSocket::makeWSFrameData(char* msg, int msgLen, std::vector<char>& outBuf)
{
std::vector<char> header;
makeWSFrameDataHeader(msgLen, header);
outBuf.insert(outBuf.begin(), header.begin(), header.end());
outBuf.insert(outBuf.end(), msg, msg+msgLen);
return 0;
}
int WebSocket::makeWSFrameDataHeader(int len, std::vector<char>& header)
{
header.push_back((char)BINARY_FRAME);
if(len <= 125)
{
header.push_back((char)len);
}
else if(len <= 65535)
{
header.push_back((char)126);//16 bit length follows
header.push_back((char)((len >> 8) & 0xFF));// leftmost first
header.push_back((char)(len & 0xFF));
}
else // >2^16-1 (65535)
{
header.push_back((char)127);//64 bit length follows
// write 8 bytes length (significant first)
// since msg_length is int it can be no longer than 4 bytes = 2^32-1
// padd zeroes for the first 4 bytes
for(int i=3; i>=0; i--)
{
header.push_back((char)0);
}
// write the actual 32bit msg_length in the next 4 bytes
for(int i=3; i>=0; i--)
{
header.push_back((char)((len >> 8*i) & 0xFF));
}
}
return 0;
}
3. BaseFunc.h
#include <openssl/pem.h>
#include <openssl/bio.h>
#include <openssl/evp.h>
// base64 編碼
int base64_encode(char *in_str, int in_len, char *out_str)
{
BIO *b64, *bio;
BUF_MEM *bptr = NULL;
size_t size = 0;
if (in_str == NULL || out_str == NULL)
return -1;
b64 = BIO_new(BIO_f_base64());
bio = BIO_new(BIO_s_mem());
bio = BIO_push(b64, bio);
BIO_write(bio, in_str, in_len);
BIO_flush(bio);
BIO_get_mem_ptr(bio, &bptr);
memcpy(out_str, bptr->data, bptr->length);
out_str[bptr->length] = '\0';
size = bptr->length;
BIO_free_all(bio);
return 0;
}
// base64 解碼
int base64_decode(char *in_str, int in_len, char *out_str)
{
BIO *b64, *bio;
BUF_MEM *bptr = NULL;
//int counts;
int size = 0;
if (in_str == NULL || out_str == NULL)
return -1;
b64 = BIO_new(BIO_f_base64());
BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
bio = BIO_new_mem_buf(in_str, in_len);
bio = BIO_push(b64, bio);
size = BIO_read(bio, out_str, in_len);
out_str[size] = '\0';
BIO_free_all(bio);
return 0;
}
