Linux C/C++ websocket协议与服务器实现

简介: Linux C/C++ websocket协议与服务器实现

一、websocket

webService、webSocket、socket、http之间的区别

Http、Socket、WebSocket之间联系与区别

Socket 与 WebSocket

二、握手 handshake

进行TCP三次握手建立连接后

对于 WebSocket 来说,它必须依赖 HTTP 协议进行一次握手 ,握手成功后,数据就直接从 TCP 通道传输,与 HTTP 无关了

1.客户端发送一个请求给服务器

2.websocket把从中的key(websocketkey)解析出来,解析出来之后,与GUID(固定值,客户端和服务端都率先知道)做一个连接, 对结果做一个哈希,再做一个base64 编码给 客户端

3.客户端就会验证,如果成功了,就会从握手状态进入 Transmission状态

服务端先要把下面的 请求中的 websocketkey给解析出来

这是GUID

接下来

三、传输transmission

传输的格式

如果payload len 长度小于126那么只需要用payload len那一段,如果payload len 长度为126,那么就额外要用蓝色那部分,如果payload len长度为127,那么就还要额外用蓝色和黄色那一部分

1.当长度<126时候

payload Data的位置,要是ev->buffer 多6个字节。

如果不解密的话,直接从客户端发送数据过来,发现是一个密文

文档中看到,有长度为4的数组 mask_key[4],

payload[i]=payload[i]^mask_key[i%4],来进行umask

这些MASK标志位是由客户端发送过来的,只要置为1了,就要进行unmask,mask_key也是客户端发过来的

四、完整代码

实现websocket

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#include <openssl/sha.h>
#include <openssl/pem.h>
#include <openssl/bio.h>
#include <openssl/evp.h>
#define BUFFER_LENGTH   4096
#define MAX_EPOLL_EVENTS  1024
#define SERVER_PORT     8888
#define PORT_COUNT      100
#define   GUID  "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
//定义几种状态(握手、传输、结束)
enum {
  WS_HANDSHARK = 0,
  WS_TRANMISSION = 1,
  WS_END = 2,
};
//定义websocket 头部操作数 (下面利用了结构体的位域  给每个变量分配空间)
typedef struct _ws_ophdr {   //websocket   operator holder 操作符
  //注意opcode对应的是高位,fin是低位。(要根据网络字节序来)
  unsigned char opcode:4,
          rsv3:1,
          rsv2:1,
          rsv1:1,
          fin:1;
  unsigned char pl_len:7,
          mask:1;
} ws_ophdr;
typedef struct _ws_head_126 {
  unsigned short payload_length;
  char mask_key[4];
} ws_head_126;
typedef struct _ws_head_127 {
  long long payload_length;
  char mask_key[4];
} ws_head_127;
typedef int NCALLBACK(int ,int, void*);
struct ntyevent {
  int fd;
  int events;
  void *arg;
  int (*callback)(int fd, int events, void *arg);
  int status;
  char buffer[BUFFER_LENGTH];
  int length;
  long last_active;
  int status_machine; //状态
};
struct eventblock {
  struct eventblock *next;
  struct ntyevent *events;
};
struct ntyreactor {
  int epfd;
  int blkcnt;
  struct eventblock *evblk; //fd --> 100w
};
int recv_cb(int fd, int events, void *arg);
int send_cb(int fd, int events, void *arg);
struct ntyevent *ntyreactor_idx(struct ntyreactor *reactor, int sockfd);
void nty_event_set(struct ntyevent *ev, int fd, NCALLBACK callback, void *arg) {
  ev->fd = fd;
  ev->callback = callback;
  ev->events = 0;
  ev->arg = arg;
  ev->last_active = time(NULL);
  return ;
}
int nty_event_add(int epfd, int events, struct ntyevent *ev) {
  struct epoll_event ep_ev = {0, {0}};
  ep_ev.data.ptr = ev;
  ep_ev.events = ev->events = events;
  int op;
  if (ev->status == 1) {
    op = EPOLL_CTL_MOD;
  } else {
    op = EPOLL_CTL_ADD;
    ev->status = 1;
  }
  if (epoll_ctl(epfd, op, ev->fd, &ep_ev) < 0) {
    printf("event add failed [fd=%d], events[%d]\n", ev->fd, events);
    return -1;
  }
  return 0;
}
int nty_event_del(int epfd, struct ntyevent *ev) {
  struct epoll_event ep_ev = {0, {0}};
  if (ev->status != 1) {
    return -1;
  }
  ep_ev.data.ptr = ev;
  ev->status = 0;
  epoll_ctl(epfd, EPOLL_CTL_DEL, ev->fd, &ep_ev);
  return 0;
}
//base64_encode(直接用就行了)
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-1] = '\0';    
  size = bptr->length;    
  BIO_free_all(bio);    
  return size;
}
int readline(char *allbuf, int idx, char *linebuf) {
  int len = strlen(allbuf);
  for(;idx < len;idx ++) {
    if (allbuf[idx] == '\r' && allbuf[idx+1] == '\n') {
      return idx+2;
    } else {
      *(linebuf++) = allbuf[idx];
    }
  }
  return -1;
}
/*
ev->buffer :
ev->length
GET / HTTP/1.1
Host: 192.168.232.128:8888
Connection: Upgrade
Pragma: no-cache
Cache-Control: no-cache
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36
Upgrade: websocket
Origin: null
Sec-WebSocket-Version: 13
Accept-Encoding: gzip, deflate
Accept-Language: zh-TW,zh;q=0.9,en-US;q=0.8,en;q=0.7
Sec-WebSocket-Key: QWz1vB/77j8J8JcT/qtiLQ==
Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits
str = "QWz1vB/77j8J8JcT/qtiLQ==258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
sha = SHA1(str);
value = base64_encode(sha);
*/
// 19 : length of "Sec-WebSocket-Key: "
#define WEBSOCK_KEY_LENGTH  19
int handshark(struct ntyevent *ev) {
  //ev->buffer , ev->length
  char linebuf[1024] = {0};
  int idx = 0;
  char sec_data[128] = {0};
  char sec_accept[32] = {0};
  do {
    memset(linebuf, 0, 1024);
    idx = readline(ev->buffer, idx, linebuf);
    if (strstr(linebuf, "Sec-WebSocket-Key")) {//找到websocketkey这行
      //linebuf: Sec-WebSocket-Key: QWz1vB/77j8J8JcT/qtiLQ==
      strcat(linebuf, GUID);
      //linebuf: 
      //Sec-WebSocket-Key: QWz1vB/77j8J8JcT/qtiLQ==258EAFA5-E914-47DA-95CA-C5AB0DC85B11
      SHA1(linebuf + WEBSOCK_KEY_LENGTH, strlen(linebuf + WEBSOCK_KEY_LENGTH), sec_data); // openssl
      base64_encode(sec_data, strlen(sec_data), sec_accept);
      memset(ev->buffer, 0, BUFFER_LENGTH); 
      ev->length = sprintf(ev->buffer, "HTTP/1.1 101 Switching Protocols\r\n"
          "Upgrade: websocket\r\n"
          "Connection: Upgrade\r\n"
          "Sec-WebSocket-Accept: %s\r\n\r\n", sec_accept);
      printf("ws response : %s\n", ev->buffer);
      break;
    }
  } while((ev->buffer[idx] != '\r' || ev->buffer[idx+1] != '\n') && idx != -1 );
  return 0;
}
void umask(char *payload, int length, char *mask_key) {
  int i = 0;
  for (i = 0;i < length;i ++) {
    payload[i] ^= mask_key[i%4];
  }
}
int transmission(struct ntyevent *ev) {
  //ev->buffer; ev->length
  ws_ophdr *hdr = (ws_ophdr*)ev->buffer;//读出来的数据存在buffer中,只要把前2个字节转为websocket协议的就行了   
  printf("length: %d\n", hdr->pl_len);
  if (hdr->pl_len < 126) { //
    unsigned char *payload = ev->buffer + sizeof(ws_ophdr) + 4; // 6  payload length < 126        ws_ophdr占2个字节
    if (hdr->mask) { // mask set 1
      umask(payload, hdr->pl_len, ev->buffer+2);
    }
    printf("payload : %s\n", payload);
  } else if (hdr->pl_len == 126) {
    ws_head_126 *hdr126 = (ws_head_126*)(ev->buffer + sizeof(ws_ophdr));
    //.....
  } else {
    ws_head_127 *hdr127 = (ws_head_127*)(ev->buffer + sizeof(ws_ophdr));
    //.....
  }
}
int websocket_request(struct ntyevent *ev) {
  if (ev->status_machine == WS_HANDSHARK) {
    ev->status_machine = WS_TRANMISSION;
    handshark(ev);
  } else if (ev->status_machine == WS_TRANMISSION) {
    transmission(ev);
  } else {
  }
  printf("websocket_request --> %d\n", ev->status_machine);
}
int recv_cb(int fd, int events, void *arg) {
  struct ntyreactor *reactor = (struct ntyreactor*)arg;
  struct ntyevent *ev = ntyreactor_idx(reactor, fd);
  int len = recv(fd, ev->buffer, BUFFER_LENGTH , 0); // 
  if (len > 0) {
    ev->length = len;
    ev->buffer[len] = '\0';
    printf("C[%d]: machine: %d\n", fd, ev->status_machine);
    websocket_request(ev);
    nty_event_del(reactor->epfd, ev);
    nty_event_set(ev, fd, send_cb, reactor);
    nty_event_add(reactor->epfd, EPOLLOUT, ev);
  } else if (len == 0) {
    nty_event_del(reactor->epfd, ev);
    close(ev->fd);
    //printf("[fd=%d] pos[%ld], closed\n", fd, ev-reactor->events);
  } else {
    nty_event_del(reactor->epfd, ev);
    close(ev->fd);
    printf("recv[fd=%d] error[%d]:%s\n", fd, errno, strerror(errno));
  }
  return len;
}
int send_cb(int fd, int events, void *arg) {
  struct ntyreactor *reactor = (struct ntyreactor*)arg;
  struct ntyevent *ev = ntyreactor_idx(reactor, fd);
  int len = send(fd, ev->buffer, ev->length, 0);
  if (len > 0) {
    printf("send[fd=%d], [%d]%s\n", fd, len, ev->buffer);
    nty_event_del(reactor->epfd, ev);
    nty_event_set(ev, fd, recv_cb, reactor);
    nty_event_add(reactor->epfd, EPOLLIN, ev);
  } else {
    close(ev->fd);
    nty_event_del(reactor->epfd, ev);
    printf("send[fd=%d] error %s\n", fd, strerror(errno));
  }
  return len;
}
int accept_cb(int fd, int events, void *arg) {
  struct ntyreactor *reactor = (struct ntyreactor*)arg;
  if (reactor == NULL) return -1;
  struct sockaddr_in client_addr;
  socklen_t len = sizeof(client_addr);
  int clientfd;
  if ((clientfd = accept(fd, (struct sockaddr*)&client_addr, &len)) == -1) {
    if (errno != EAGAIN && errno != EINTR) {
    }
    printf("accept: %s\n", strerror(errno));
    return -1;
  }
  int flag = 0;
  if ((flag = fcntl(clientfd, F_SETFL, O_NONBLOCK)) < 0) {
    printf("%s: fcntl nonblocking failed, %d\n", __func__, MAX_EPOLL_EVENTS);
    return -1;
  }
  struct ntyevent *event = ntyreactor_idx(reactor, clientfd);
  event->status_machine = WS_HANDSHARK;//初始化
  nty_event_set(event, clientfd, recv_cb, reactor);
  nty_event_add(reactor->epfd, EPOLLIN, event);
  printf("new connect [%s:%d], pos[%d]\n", 
    inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port), clientfd);
  return 0;
}
int init_sock(short port) {
  int fd = socket(AF_INET, SOCK_STREAM, 0);
  fcntl(fd, F_SETFL, O_NONBLOCK);
  struct sockaddr_in server_addr;
  memset(&server_addr, 0, sizeof(server_addr));
  server_addr.sin_family = AF_INET;
  server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
  server_addr.sin_port = htons(port);
  bind(fd, (struct sockaddr*)&server_addr, sizeof(server_addr));
  if (listen(fd, 20) < 0) {
    printf("listen failed : %s\n", strerror(errno));
  }
  return fd;
}
int ntyreactor_alloc(struct ntyreactor *reactor) {
  if (reactor == NULL) return -1;
  if (reactor->evblk == NULL) return -1;
  struct eventblock *blk = reactor->evblk;
  while (blk->next != NULL) {
    blk = blk->next;
  }
  struct ntyevent *evs = (struct ntyevent*)malloc((MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
  if (evs == NULL) {
    printf("ntyreactor_alloc ntyevents failed\n");
    return -2;
  }
  memset(evs, 0, (MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
  struct eventblock *block = (struct eventblock *)malloc(sizeof(struct eventblock));
  if (block == NULL) {
    printf("ntyreactor_alloc eventblock failed\n");
    return -2;
  }
  memset(block, 0, sizeof(struct eventblock));
  block->events = evs;
  block->next = NULL;
  blk->next = block;
  reactor->blkcnt ++; //
  return 0;
}
struct ntyevent *ntyreactor_idx(struct ntyreactor *reactor, int sockfd) {
  int blkidx = sockfd / MAX_EPOLL_EVENTS;
  while (blkidx >= reactor->blkcnt) {
    ntyreactor_alloc(reactor);
  }
  int i = 0;
  struct eventblock *blk = reactor->evblk;
  while(i ++ < blkidx && blk != NULL) {
    blk = blk->next;
  }
  return &blk->events[sockfd % MAX_EPOLL_EVENTS];
}
int ntyreactor_init(struct ntyreactor *reactor) {
  if (reactor == NULL) return -1;
  memset(reactor, 0, sizeof(struct ntyreactor));
  reactor->epfd = epoll_create(1);
  if (reactor->epfd <= 0) {
    printf("create epfd in %s err %s\n", __func__, strerror(errno));
    return -2;
  }
  struct ntyevent *evs = (struct ntyevent*)malloc((MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
  if (evs == NULL) {
    printf("ntyreactor_alloc ntyevents failed\n");
    return -2;
  }
  memset(evs, 0, (MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
  struct eventblock *block = (struct eventblock *)malloc(sizeof(struct eventblock));
  if (block == NULL) {
    printf("ntyreactor_alloc eventblock failed\n");
    return -2;
  }
  memset(block, 0, sizeof(struct eventblock));
  block->events = evs;
  block->next = NULL;
  reactor->evblk = block;
  reactor->blkcnt = 1;
  return 0;
}
int ntyreactor_destory(struct ntyreactor *reactor) {
  close(reactor->epfd);
  //free(reactor->events);
  struct eventblock *blk = reactor->evblk;
  struct eventblock *blk_next = NULL;
  while (blk != NULL) {
    blk_next = blk->next;
    free(blk->events);
    free(blk);
    blk = blk_next;
  }
  return 0;
}
int ntyreactor_addlistener(struct ntyreactor *reactor, int sockfd, NCALLBACK *acceptor) {
  if (reactor == NULL) return -1;
  if (reactor->evblk == NULL) return -1;
  //reactor->evblk->events[sockfd];
  struct ntyevent *event = ntyreactor_idx(reactor, sockfd);
  nty_event_set(event, sockfd, acceptor, reactor);
  nty_event_add(reactor->epfd, EPOLLIN, event);
  return 0;
}
int ntyreactor_run(struct ntyreactor *reactor) {
  if (reactor == NULL) return -1;
  if (reactor->epfd < 0) return -1;
  if (reactor->evblk == NULL) return -1;
  struct epoll_event events[MAX_EPOLL_EVENTS+1];
  int checkpos = 0, i;
  while (1) {
/*
    long now = time(NULL);
    for (i = 0;i < 100;i ++, checkpos ++) {
      if (checkpos == MAX_EPOLL_EVENTS) {
        checkpos = 0;
      }
      if (reactor->events[checkpos].status != 1) {
        continue;
      }
      long duration = now - reactor->events[checkpos].last_active;
      if (duration >= 60) {
        close(reactor->events[checkpos].fd);
        printf("[fd=%d] timeout\n", reactor->events[checkpos].fd);
        nty_event_del(reactor->epfd, &reactor->events[checkpos]);
      }
    }
*/
    int nready = epoll_wait(reactor->epfd, events, MAX_EPOLL_EVENTS, 1000);
    if (nready < 0) {
      printf("epoll_wait error, exit\n");
      continue;
    }
    for (i = 0;i < nready;i ++) {
      struct ntyevent *ev = (struct ntyevent*)events[i].data.ptr;
      if ((events[i].events & EPOLLIN) && (ev->events & EPOLLIN)) {
        ev->callback(ev->fd, events[i].events, ev->arg);
      }
      if ((events[i].events & EPOLLOUT) && (ev->events & EPOLLOUT)) {
        ev->callback(ev->fd, events[i].events, ev->arg);
      }
    }
  }
}
// 3, 6w, 1, 100 == 
// <remoteip, remoteport, localip, localport>
int main(int argc, char *argv[]) {
  unsigned short port = SERVER_PORT; // listen 8888
  if (argc == 2) {
    port = atoi(argv[1]);
  }
  struct ntyreactor *reactor = (struct ntyreactor*)malloc(sizeof(struct ntyreactor));
  ntyreactor_init(reactor);
  int i = 0;
  int sockfds[PORT_COUNT] = {0};
  for (i = 0;i < PORT_COUNT;i ++) {
    sockfds[i] = init_sock(port+i);
    ntyreactor_addlistener(reactor, sockfds[i], accept_cb);
  }
  ntyreactor_run(reactor);
  ntyreactor_destory(reactor);
  for (i = 0;i < PORT_COUNT;i ++) {
    close(sockfds[i]);
  }
  free(reactor);
  return 0;
}


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