websocket服务器的创建
就这上篇文章的代码，我们会继续实现以下websocket的协议。
为什么要使用websocket呢？
它的最大特点就是，服务器可以主动向客户端推送信息，客户端也可以主动向服务器发送信息，是真正的双向平等对话，属于服务器推送技术的一种。
其他特点包括：
（1）建立在TCP协议之上，服务器端的实现比较容易。
（2）与HTTP协议有着良好的兼容性。默认端口也是80和443，并且握手阶段采用HTTP协议，因此握手时不容易屏蔽，能通过各种HTTP代理服务器。
（3）数据格式比较轻量，性能开销小，通信高效。
（4）可以发送文本，也可以发送二进制数据。
（5）没有同源限制，客户端可以与任意服务器通信。
（6）协议标识符是ws（如果加密，则为wss），服务器网址就是URL。
websocket的握手流程:
- 判断是否为WEBSOCKET的请求
- 获取KEY
- 连接KEY和GUID
- 进行SHA1的处理
- 保存SHA1后的结果，发送回客户端。
websocket 的握手的实现
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;
}
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 my_ws_handshark(struct ntyevent*ev){
int idx=0;
char sec_data[128]={0};
char sec_accept[128] = {0};
do
{
/* code */
char linebuf[1024]={0};
idx=readline(ev->buffer,idx,linebuf);
//获取到WEBSOCKET的KEY
if (strstr(linebuf,"Sec-WebSocket-Key"))
{
/* code */
strcat(linebuf,GUID);
SHA1(linebuf+19, strlen(linebuf+19), sec_data);
base64_encode(sec_data, strlen(sec_data), sec_accept);
printf("idx: %d, line: %ld\n",idx, sizeof("Sec-WebSocket-Key: "));
memcpy(ev->sec_accept, sec_accept, ACCEPT_KEY_LENGTH);
}
} while ((ev->buffer[idx]!='\r'||ev->buffer[idx]!='\n')&& idx != -1);
}
上面的代码就是我们服务端和客户端建立通信的时候，我们服务端如何解析客户端的连接请求。
下面就是我们需要返回给客户端的数据。
int my_ws_response(struct ntyevent *ev){
ev->wlength=sprintf(ev->wbuffer, "HTTP/1.1 101 Switching Protocols\r\n"
"Upgrade: websocket\r\n"
"Connection: Upgrade\r\n"
"Sec-WebSocket-Accept: %s\r\n\r\n", ev->sec_accept);
printf("response: %s\n", ev->wbuffer);
return ev->wlength;
}
现在我们的客户端应该就可以连接上我们的websocket服务器了，我们测试一下
下面就是服务器接收发送消息的处理了
首先我们先看 一下它的帧。如何进行解析
帧结构在说明中。
定义我们的帧结构，
struct ws_ophdr {
unsigned char opcode:4,
rsv3:1,
rsv2:1,
rsv1:1,
fin:1;
unsigned char pl_len:7,
mask:1;
};
由于客户端发送的数据都要设置MASK的值为1，并进行解密。
写一下如果MASK值为1的时候，进行解密的代码。
void umask(char *payload, int length, char *mask_key) {
int i = 0;
for (i = 0;i < length;i ++) {
payload[i] ^= mask_key[i%4];
}
}
之后就是我们进行消息解密的代码，我们要根据Payload的长度进行不同的处理。
如果 x值在0-125，则是payload的真实长度。
如果 x值是126，则后面2个字节形成的16位无符号整型数的值是payload的真实长度。
如果 x值是127，则后面8个字节形成的64位无符号整型数的值是payload的真实长度。
完整代码如下，这样我们就完成了我们简单的WEBsocket服务器
#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 <openssl/sha.h>
#include <openssl/pem.h>
#include <openssl/bio.h>
#include <openssl/evp.h>
#define BUFFER_LENGTH 1024
#define MAX_EPOLL_EVENTS 1024
#define SERVER_PORT 8888
#define PORT_COUNT 100
#define ACCEPT_KEY_LENGTH 64
#define GUID "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
enum {
WS_HANDSHARK = 0,
WS_TRANMISSION = 1,
WS_END = 2,
WS_COUNT
};
struct ws_ophdr {
unsigned char opcode:4,
rsv3:1,
rsv2:1,
rsv1:1,
fin:1;
unsigned char pl_len:7,
mask:1;
};
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;
char wbuffer[BUFFER_LENGTH]; //response
int wlength;
char sec_accept[ACCEPT_KEY_LENGTH];
int wsstatus; //0, 1, 2, 3
};
struct eventblock {
struct eventblock *next;
struct ntyevent *events;
};
struct ntyreactor {
int epfd;
int blkcnt;
struct eventblock *evblks;
};
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;
}
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;
}
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 my_ws_handshark(struct ntyevent*ev){
int idx=0;
char sec_data[128]={0};
char sec_accept[128] = {0};
do
{
/* code */
char linebuf[1024]={0};
idx=readline(ev->buffer,idx,linebuf);
//获取到WEBSOCKET的KEY
if (strstr(linebuf,"Sec-WebSocket-Key"))
{
/* code */
strcat(linebuf,GUID);
SHA1(linebuf+19, strlen(linebuf+19), sec_data);
base64_encode(sec_data, strlen(sec_data), sec_accept);
printf("idx: %d, line: %ld\n",idx, sizeof("Sec-WebSocket-Key: "));
memcpy(ev->sec_accept, sec_accept, ACCEPT_KEY_LENGTH);
}
} while ((ev->buffer[idx]!='\r'||ev->buffer[idx]!='\n')&& idx != -1);
}
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 ws_tranmission(struct ntyevent *ev) {
struct ws_ophdr *hdr = (struct ws_ophdr *)ev->buffer;
if (hdr->pl_len < 126) {
unsigned char *payload = NULL;
if (hdr->mask) {
payload = ev->buffer + 6;
umask(payload, hdr->pl_len, ev->buffer + 2);
} else {
payload = ev->buffer + 2;
}
printf("payload: %s\n", payload);
} else if (hdr->pl_len == 126) {
} else if (hdr->pl_len == 127) {
} else {
//assert(0);
}
}
int my_ws_response(struct ntyevent *ev){
ev->wlength=sprintf(ev->wbuffer, "HTTP/1.1 101 Switching Protocols\r\n"
"Upgrade: websocket\r\n"
"Connection: Upgrade\r\n"
"Sec-WebSocket-Accept: %s\r\n\r\n", ev->sec_accept);
printf("response: %s\n", ev->wbuffer);
return ev->wlength;
}
int my_ws_request(struct ntyevent *ev) {
if (ev->wsstatus == WS_HANDSHARK) {
my_ws_handshark(ev);
ev->wsstatus = WS_TRANMISSION;
} else if (ev->wsstatus == WS_TRANMISSION) {
ws_tranmission(ev);
}
}
int recv_cb(int fd, int events, void *arg) {
struct ntyreactor *reactor = (struct ntyreactor*)arg;
struct ntyevent *ev = ntyreactor_idx(reactor, fd);
if (ev == NULL) return -1;
int len = recv(fd, ev->buffer, BUFFER_LENGTH, 0);
nty_event_del(reactor->epfd, ev);
if (len > 0) {
ev->length = len;
ev->buffer[len] = '\0';
1(ev);
//printf("recv [%d]:%s\n", fd, ev->buffer);
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);
printf("recv_cb --> disconnect\n");
close(ev->fd);
} else {
if (errno == EAGAIN && errno == EWOULDBLOCK) { //
} else if (errno == ECONNRESET){
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);
if (ev == NULL) return -1;
my_ws_response(ev);
int len = send(fd, ev->wbuffer, ev->wlength, 0);
if (len > 0) {
printf("send[fd=%d], [%d]%s\n", fd, len, ev->wbuffer);
nty_event_del(reactor->epfd, ev);
nty_event_set(ev, fd, recv_cb, reactor);
nty_event_add(reactor->epfd, EPOLLIN, ev);
} else {
nty_event_del(reactor->epfd, ev);
close(ev->fd);
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);
if (event == NULL) return -1;
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 -1;
}
printf("listen server port : %d\n", port);
return fd;
}
int ntyreactor_alloc(struct ntyreactor *reactor) {
if (reactor == NULL) return -1;
if (reactor->evblks == NULL) return -1;
struct eventblock *blk = reactor->evblks;
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 ntyevent failed\n");
return -2;
}
memset(evs, 0, (MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
struct eventblock *block = malloc(sizeof(struct eventblock));
if (block == NULL) {
printf("ntyreactor_alloc eventblock failed\n");
return -3;
}
block->events = evs;
block->next = NULL;
blk->next = block;
reactor->blkcnt ++;
return 0;
}
struct ntyevent *ntyreactor_idx(struct ntyreactor *reactor, int sockfd) {
if (reactor == NULL) return NULL;
if (reactor->evblks == NULL) return NULL;
int blkidx = sockfd / MAX_EPOLL_EVENTS;
while (blkidx >= reactor->blkcnt) {
ntyreactor_alloc(reactor);
}
int i = 0;
struct eventblock *blk = reactor->evblks;
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("create epfd in %s err %s\n", __func__, strerror(errno));
close(reactor->epfd);
return -3;
}
memset(evs, 0, (MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
struct eventblock *block = malloc(sizeof(struct eventblock));
if (block == NULL) {
free(evs);
close(reactor->epfd);
return -3;
}
block->events = evs;
block->next = NULL;
reactor->evblks = block;
reactor->blkcnt = 1;
return 0;
}
int ntyreactor_destory(struct ntyreactor *reactor) {
close(reactor->epfd);
struct eventblock *blk = reactor->evblks;
struct eventblock *blk_next;
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->evblks == NULL) return -1;
struct ntyevent *event = ntyreactor_idx(reactor, sockfd);
if (event == NULL) return -1;
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->evblks == NULL) return -1;
struct epoll_event events[MAX_EPOLL_EVENTS+1];
int checkpos = 0, i;
while (1) {
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);
}
}
}
}
int main(int argc, char *argv[]) {
struct ntyreactor *reactor = (struct ntyreactor*)malloc(sizeof(struct ntyreactor));
ntyreactor_init(reactor);
unsigned short port = SERVER_PORT;
if (argc == 2) {
port = atoi(argv[1]);
}
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;
}
这样我们就完成简单的websocket服务器。
推荐一个零声学院免费教程，个人觉得老师讲得不错，
分享给大家：[Linux，Nginx，ZeroMQ，MySQL，Redis，
fastdfs，MongoDB，ZK，流媒体，CDN，P2P，K8S，Docker，
TCP/IP，协程，DPDK等技术内容，点击立即学习:
服务器
音视频
dpdk
Linux内核
