C++无依赖库的websocket实现

Posted 2022-08-10 北雨南萍

1. 简单websocket 客户端实现

参考源码：

见：

GitHub - hank4187yan/light-websocket-client: 非常轻量级的websocket客户端，无第三方依赖库非常轻量级的websocket客户端，无第三方依赖库. Contribute to hank4187yan/light-websocket-client development by creating an account on GitHub.https://github.com/hank4187yan/light-websocket-client

GitHub - dhbaird/easywsclient: A short and sweet WebSocket client for C++A short and sweet WebSocket client for C++. Contribute to dhbaird/easywsclient development by creating an account on GitHub.https://github.com/dhbaird/easywsclient

1.1 核心源码解析

1.1.1 创建客户端对象并连接服务端

CWebsocket* ws_cli = new CWebsocket("ws://localhost:20600/ar/9999", true);

CWebsocket::CWebsocket(const string& url, bool use_mask)

m_url = url;

sscanf(url.c_str(), "ws://%[^:/]:%d/%s", m_host, &m_port, m_path);

ret = ws_cli->connect_hostname();

int CWebsocket::connect_hostname()

struct addrinfo hints;

struct addrinfo* result;

struct addrinfo* p;

int ret = 0;

std::string origin;

m_sock_fd = INVALID_SOCKET;

char sport[16];

memset(&hints, 0, sizeof(hints));

hints.ai_family = AF_UNSPEC;

hints.ai_socktype = SOCK_STREAM;

snprintf(sport, 16, "%d", m_port);

ret = getaddrinfo(m_host, sport, &hints, &result);

if (ret != 0)

LIGHTWS_LOG("[ERR]Failed to getaddrinfo:%s\\n", gai_strerror(ret));

return LIGHTWS_ERR_CONNECT;

for (p = result; p != NULL; p = p->ai_next)

m_sock_fd = socket(p->ai_family, p->ai_socktype, p->ai_protocol);

if (m_sock_fd == INVALID_SOCKET)

continue;

ret = connect(m_sock_fd, p->ai_addr, p->ai_addrlen);

if (ret != SOCKET_ERROR)

break;

closesocket(m_sock_fd);

m_sock_fd = INVALID_SOCKET;

freeaddrinfo(result);

if (m_sock_fd == INVALID_SOCKET)

LIGHTWS_LOG("[ERR]Unable to connect to %s:%d\\n", m_host, m_port);

return LIGHTWS_ERR_CONNECT;

1.1.2 和服务端进行websocket握手

// Websocket handshake

char line[1024];

int status;

int i;

snprintf(line, 1024, "GET /%s HTTP/1.1\\r\\n", m_path);

::send(m_sock_fd, line, strlen(line), 0);

if (m_port == 80)

snprintf(line, 1024, "Host: %s\\r\\n", m_host);

::send(m_sock_fd, line, strlen(line), 0);

else

snprintf(line, 1024, "Host: %s:%d\\r\\n", m_host, m_port);

::send(m_sock_fd, line, strlen(line), 0);

snprintf(line, 1024, "Upgrade: websocket\\r\\n");

::send(m_sock_fd, line, strlen(line), 0);

snprintf(line, 1024, "Connection: Upgrade\\r\\n");

::send(m_sock_fd, line, strlen(line), 0);

if (!origin.empty())

snprintf(line, 1024, "Origin: %s\\r\\n", origin.c_str());

::send(m_sock_fd, line, strlen(line), 0);

snprintf(line, 1024, "Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw==\\r\\n");

::send(m_sock_fd, line, strlen(line), 0);

snprintf(line, 1024, "Sec-WebSocket-Version: 13\\r\\n");

::send(m_sock_fd, line, strlen(line), 0);

snprintf(line, 1024, "\\r\\n");

::send(m_sock_fd, line, strlen(line), 0);

for (i = 0; i < 2 || (i < 1023 && line[i-2] != '\\r' && line[i-1] != '\\n'); ++i)

if (recv(m_sock_fd, line+i, 1, 0) == 0)

return LIGTHWS_ERR_HANDSHAKE;

line[i] = 0;

if (i == 1023)

LIGHTWS_LOG("ERROR: Got invalid status line connecting to: %s\\n", m_url.c_str());

return LIGTHWS_ERR_HANDSHAKE;

if (sscanf(line, "HTTP/1.1 %d", &status) != 1 || status != 101)

LIGHTWS_LOG("ERROR: Got bad status connecting to %s: %s", m_url.c_str(), line);

return LIGTHWS_ERR_HANDSHAKE;

// TODO: verify response headers,

while (true)

for (i = 0; i < 2 || (i < 1023 && line[i-2] != '\\r' && line[i-1] != '\\n'); ++i)

if (recv(m_sock_fd, line+i, 1, 0) == 0)

return LIGTHWS_ERR_HANDSHAKE;

if (line[0] == '\\r' && line[1] == '\\n')

break;

1.1.3 对要发送数据进行mask处理

const uint8_t masking_key[4] = 0x12, 0x34, 0x56, 0x78 ;

// TODO: consider acquiring a lock on txbuf...

if (m_ws_state == CLOSING || m_ws_state == CLOSED)

return LIGHTWS_ERR_CLOSED;

std::vector<uint8_t> header;

header.assign(2 + (message_size >= 126 ? 2 : 0) + (message_size >= 65536 ? 6 : 0) + (m_use_mask ? 4 : 0), 0);

header[0] = 0x80 | type;

if (message_size < 126)

header[1] = (message_size & 0xff) | (m_use_mask ? 0x80 : 0);

if (m_use_mask)

header[2] = masking_key[0];

header[3] = masking_key[1];

header[4] = masking_key[2];

header[5] = masking_key[3];

else if (message_size < 65536)

header[1] = 126 | (m_use_mask ? 0x80 : 0);

header[2] = (message_size >> 8) & 0xff;

header[3] = (message_size >> 0) & 0xff;

if (m_use_mask)

header[4] = masking_key[0];

header[5] = masking_key[1];

header[6] = masking_key[2];

header[7] = masking_key[3];

else // TODO: run coverage testing here

header[1] = 127 | (m_use_mask ? 0x80 : 0);

header[2] = (message_size >> 56) & 0xff;

header[3] = (message_size >> 48) & 0xff;

header[4] = (message_size >> 40) & 0xff;

header[5] = (message_size >> 32) & 0xff;

header[6] = (message_size >> 24) & 0xff;

header[7] = (message_size >> 16) & 0xff;

header[8] = (message_size >> 8) & 0xff;

header[9] = (message_size >> 0) & 0xff;

if (m_use_mask)

header[10] = masking_key[0];

header[11] = masking_key[1];

header[12] = masking_key[2];

header[13] = masking_key[3];

// N.B. - txbuf will keep growing until it can be transmitted over the socket:

m_txbuf.insert(m_txbuf.end(), header.begin(), header.end());

m_txbuf.insert(m_txbuf.end(), message_begin, message_end);

if (m_use_mask)

size_t message_offset = m_txbuf.size() - message_size;

for (size_t i = 0; i != message_size; ++i)

m_txbuf[message_offset + i] ^= masking_key[i&0x3];

1.1.4 通过socket发送mask处理后的数据

// 发送request

while (m_txbuf.size())

int ret = ::send(m_sock_fd, (char*)&m_txbuf[0], m_txbuf.size(), 0);

if (false) //

else if (ret < 0 && (socketerrno == SOCKET_EWOULDBLOCK || socketerrno == SOCKET_EAGAIN_EINPROGRESS))

break;

else if (ret <= 0)

closesocket(m_sock_fd);

m_ws_state = CLOSED;

fputs(ret < 0 ? "Connection error!\\n" : "Connection closed!\\n", stderr);

break;

else

m_txbuf.erase(m_txbuf.begin(), m_txbuf.begin() + ret);

1.1.5 接收response

// 接收服务端的response

while (true)

// FD_ISSET(0, &rfds) will be true

int N = m_rxbuf.size();

ssize_t ret;

m_rxbuf.resize(N + 1500);

ret = recv(m_sock_fd, (char*)&m_rxbuf[0] + N, 1500, 0);

if (false)

else if (ret < 0 && (socketerrno == SOCKET_EWOULDBLOCK || socketerrno == SOCKET_EAGAIN_EINPROGRESS))

m_rxbuf.resize(N);

break;

else if (ret <= 0)

m_rxbuf.resize(N);

closesocket(m_sock_fd);

m_ws_state = CLOSED;

fputs(ret < 0 ? "Connection error!\\n" : "Connection closed!\\n", stderr);

break;

else

m_rxbuf.resize(N + ret);

1.1.6 解析response数据

while (true)

ws_header_type_t ws;

if (m_rxbuf.size() < 2)

return LIGHTWS_ERR_DISPATCH; /* Need at least 2 */

const uint8_t * data = (uint8_t *) &m_rxbuf[0]; // peek, but don't consume

ws.fin = (data[0] & 0x80) == 0x80;

ws.opcode = (ws_header_type_t::EOpcodeType) (data[0] & 0x0f);

ws.mask = (data[1] & 0x80) == 0x80;

ws.N0 = (data[1] & 0x7f);

ws.header_size = 2 + (ws.N0 == 126? 2 : 0) + (ws.N0 == 127? 8 : 0) + (ws.mask? 4 : 0);

if (m_rxbuf.size() < ws.header_size)

return LIGHTWS_ERR_DISPATCH; /* Need: ws.header_size - rxbuf.size() */

int i = 0;

if (ws.N0 < 126)

ws.N = ws.N0;

i = 2;

else if (ws.N0 == 126)

ws.N = 0;

ws.N |= ((uint64_t) data[2]) << 8;

ws.N |= ((uint64_t) data[3]) << 0;

i = 4;

else if (ws.N0 == 127)

ws.N = 0;

ws.N |= ((uint64_t) data[2]) << 56;

ws.N |= ((uint64_t) data[3]) << 48;

ws.N |= ((uint64_t) data[4]) << 40;

ws.N |= ((uint64_t) data[5]) << 32;

ws.N |= ((uint64_t) data[6]) << 24;

ws.N |= ((uint64_t) data[7]) << 16;

ws.N |= ((uint64_t) data[8]) << 8;

ws.N |= ((uint64_t) data[9]) << 0;

i = 10;

if (ws.N & 0x8000000000000000ull)

// https://tools.ietf.org/html/rfc6455 writes the "the most

// significant bit MUST be 0."

//

// We can't drop the frame, because (1) we don't we don't

// know how much data to skip over to find the next header,

// and (2) this would be an impractically long length, even

// if it were valid. So just close() and return immediately

// for now.

m_is_rx_bad = true;

LIGHTWS_LOG("ERROR: Frame has invalid frame length. Closing.\\n");

close();

return LIGHTWS_ERR_DISPATCH;

if (ws.mask)

ws.masking_key[0] = ((uint8_t) data[i+0]) << 0;

ws.masking_key[1] = ((uint8_t) data[i+1]) << 0;

ws.masking_key[2] = ((uint8_t) data[i+2]) << 0;

ws.masking_key[3] = ((uint8_t) data[i+3]) << 0;

else

ws.masking_key[0] = 0;

ws.masking_key[1] = 0;

ws.masking_key[2] = 0;

ws.masking_key[3] = 0;

// Note: The checks above should hopefully ensure this addition

// cannot overflow:

if (m_rxbuf.size() < ws.header_size+ws.N)

return LIGHTWS_ERR_DISPATCH; /* Need: ws.header_size+ws.N - rxbuf.size() */

// We got a whole message, now do something with it:

if (ws.opcode == ws_header_type_t::EOpcodeType::TEXT_FRAME

|| ws.opcode == ws_header_type_t::EOpcodeType::BINARY_FRAME

|| ws.opcode == ws_header_type_t::EOpcodeType::CONTINUATION)

if (ws.mask)

for (size_t i = 0; i != ws.N; ++i)

m_rxbuf[i+ws.header_size] ^= ws.masking_key[i&0x3];

m_recved_data.insert(m_recved_data.end(), m_rxbuf.begin()+ws.header_size,

m_rxbuf.begin()+ws.header_size+(size_t)ws.N);// just feed

if (ws.fin)

//callable((const std::vector<uint8_t>) m_recved_data);

std::string stringMessage(m_recved_data.begin(), m_recved_data.end());

printf(">>> %s\\n", stringMessage.c_str());

m_recved_data.erase(m_recved_data.begin(), m_recved_data.end());

std::vector<uint8_t> ().swap(m_recved_data);// free memory

else if (ws.opcode == ws_header_type_t::EOpcodeType::PING)

if (ws.mask)

for (size_t i = 0; i != ws.N; ++i)

m_rxbuf[i+ws.header_size] ^= ws.masking_key[i&0x3];

std::string data(m_rxbuf.begin()+ws.header_size, m_rxbuf.begin()+ws.header_size+(size_t)ws.N);

send_data(ws_header_type_t::PONG, data.size(), data.begin(), data.end());

else if (ws.opcode == ws_header_type_t::EOpcodeType::PONG)

else if (ws.opcode == ws_header_type_t::EOpcodeType::CLOSE)

close();

else

fprintf(stderr, "ERROR: Got unexpected WebSocket message.\\n");

close();

m_rxbuf.erase(m_rxbuf.begin(), m_rxbuf.begin() + ws.header_size+(size_t)ws.N);

2. 简单websocket 服务端实现

完整源码：

见：GitHub - javapretty/websocket: C++解析websocket协议C++解析websocket协议. Contribute to javapretty/websocket development by creating an account on GitHub.https://github.com/javapretty/websocket.git

2.1 核心源码解析

2.1.1 TCP服务端端口监听

// socket创建

listenfd_ = socket(AF_INET, SOCK_STREAM, 0);

// 绑定端口并启动监听

struct sockaddr_in server_addr;

memset(&server_addr, 0, sizeof(sockaddr_in));

server_addr.sin_family = AF_INET;

server_addr.sin_addr.s_addr = htonl(INADDR_ANY);

server_addr.sin_port = htons(PORT);

bind(listenfd_, (struct sockaddr *)(&server_addr), sizeof(server_addr))

listen(listenfd_, 5)

2.1.2 epoll创建并注册事件

/*

typedef std::map<int, Websocket_Handler *> WEB_SOCKET_HANDLER_MAP;

WEB_SOCKET_HANDLER_MAP websocket_handler_map_;

websocket_handler_map_ 是:

以socket的句柄为索引的Websocket_handler对象映射表，

以实现服务端对每个socket连接都有一个对应的对象来处理；

*/

// epoll句柄创建

epollfd_ = epoll_create(MAXEVENTSSIZE);

/* 注册监听端口socket的 EPOLLIN事件到epoll句柄 */

ctl_event(listenfd_, true);

void Network_Interface::ctl_event(int fd, bool flag)

struct epoll_event ev;

ev.data.fd = fd;

ev.events = flag ? EPOLLIN : 0;

epoll_ctl(epollfd_, flag ? EPOLL_CTL_ADD : EPOLL_CTL_DEL, fd, &ev);

if(flag)

set_noblock(fd);

websocket_handler_map_[fd] = new Websocket_Handler(fd);

if(fd != listenfd_) DEBUG_LOG("fd: %d 加入epoll循环", fd);

else

close(fd);

delete websocket_handler_map_[fd];

websocket_handler_map_.erase(fd);

DEBUG_LOG("fd: %d 退出epoll循环", fd);

2.1.3 epoll主循环

#define TIMEWAIT 100

int Network_Interface::epoll_loop()

struct sockaddr_in client_addr;

struct epoll_event events[MAXEVENTSSIZE];

while(true)

nfds = epoll_wait(epollfd_, events, MAXEVENTSSIZE, TIMEWAIT);

for(int i = 0; i < nfds; i++)

// 接受客户端的连接请求，

// 并注册这个连接socket句柄的EPOLLIN事件监听到epoll

if(events[i].data.fd == listenfd_)

fd = accept(listenfd_, (struct sockaddr *)&client_addr, &clilen);

ctl_event(fd, true);

// 接收到了客户端发送的数据，

// 将数据读取到句柄的buffer， 然后进行处理

else if(events[i].events & EPOLLIN)

Websocket_Handler *handler = websocket_handler_map_[fd];

bufflen = read(fd, handler->getbuff(), BUFFLEN)

handler->process();

return 0;

2.1.4 websocket的 request处理

int Websocket_Handler::process()

// 第一次时需要进行websocket握手

if(status_ == WEBSOCKET_UNCONNECT)

return handshark();

// 非第一次时，则进行数据处理：

// 提取数据，并印出来

request_->fetch_websocket_info(buff_);

request_->print();

memset(buff_, 0, sizeof(buff_));

return 0;

2.1.4.1 websocket的握手

主要是根据Websocket握手包进行解析，

然后根据Sec-WebSocket-Key进行SHA1哈希，生成相应的key,

返回给客户端，与客户端进行握手；

int Websocket_Handler::handshark()

char request[1024] = ;

status_ = WEBSOCKET_HANDSHARKED;

fetch_http_info(); // 提取出HTTP头的每行

parse_str(request); // 解析头，并生成新的key

memset(buff_, 0, sizeof(buff_));

// 将新的握手数据发给客户端，完成握手；

return send_data(request);

// 逐行解析，获得Websocket的数据

int Websocket_Handler::fetch_http_info()

std::istringstream s(buff_);

std::string request;

std::getline(s, request);

if (request[request.size()-1] == '\\r')

request.erase(request.end()-1);

else

return -1;

std::string header;

std::string::size_type end;

while (std::getline(s, header) && header != "\\r")

if (header[header.size()-1] != '\\r')

continue; //end

else

header.erase(header.end()-1); //remove last char

end = header.find(": ",0);

if (end != std::string::npos)

std::string key = header.substr(0,end);

std::string value = header.substr(end+2);

header_map_[key] = value;

return 0;

// 检查每一项具体HTTP头的内容，重新生成新的key

void Websocket_Handler::parse_str(char *request)

strcat(request, "HTTP/1.1 101 Switching Protocols\\r\\n");

strcat(request, "Connection: upgrade\\r\\n");

strcat(request, "Sec-WebSocket-Accept: ");

std::string server_key = header_map_["Sec-WebSocket-Key"];

server_key += MAGIC_KEY;

SHA1 sha;

unsigned int message_digest[5];

sha.Reset();

sha << server_key.c_str();

sha.Result(message_digest);

for (int i = 0; i < 5; i++)

message_digest[i] = htonl(message_digest[i]);

server_key = base64_encode(reinterpret_cast<const unsigned char*>(message_digest),20);

server_key += "\\r\\n";

strcat(request, server_key.c_str());

strcat(request, "Upgrade: websocket\\r\\n\\r\\n");

int Websocket_Handler::send_data(char *buff)

return write(fd_, buff, strlen(buff));

2.1.4.2 非握手的数据处理

提取数据头和数据body；

int Websocket_Request::fetch_websocket_info(char *msg)

int pos = 0;

fetch_fin(msg, pos);

fetch_opcode(msg, pos);

fetch_mask(msg, pos);

fetch_payload_length(msg, pos);

fetch_masking_key(msg, pos);

return fetch_payload(msg, pos);

2.1.5 websocket的response处理

没有实现；