libuv库TCP echo-server

学习libuv库，写TCP echo-server

大部分代码都来自libuv源码test目录下echo-server.c文件。

我自己添加了一点代码，通过uv_read_start函数更改read_cb函数

使得第奇数次客户端输入一行文字后，服务端原样返回，

偶数次输入一行文字，服务端将输入的一行文字逆序后返回

结果如下：

cheng@debian:~$ telnet 127.0.0.1 7890
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
helo
helo
helo
oleh
00000111111
00000111111
00000111111
11111100000

---------------------------------------------------------总结的分割线---------------------------------------------------------------------------------

通过echo-server这个程序，可以学习怎么利用libuv，像完成原始socket网络编程那样，

创建socket, bind, listen, accept过程。

只是在异步，非阻塞的方式编程时，需要通过事先为某个事件发生时应该调用的回调

在echo-server程序中，通过uv_listen函数注册连接回调函数

uv_read_start注册读函数

uv_write注册写函数

在头文件uv.h看这三个函数的函数原型，可以很清楚的知道每个参数的意义

------------------------------------------------------------------------------------------------------------------------------------------------------------

修改过的echo-server.c代码：

 /* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to
  * deal in the Software without restriction, including without limitation the
  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  * sell copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  * IN THE SOFTWARE.
  */

 #include
 #include
 #include
 #include
 #include

 #define ASSERT assert
 #define TEST_PORT 7890


 static void reversed(char *s, int len)
 {
     char c;
     char *end;
     end = s + len - 1;
     while (*end == '\r' || *end == '\n') {
         end--;
     }
     while (end > s) {
         c = *end;
         *end = *s;
         *s = c;
         end--;
         s++;
     }
 }


 typedef struct {
   uv_write_t req;
   uv_buf_t buf;
 } write_req_t;

 #define FATAL(msg)                                        \
   do {                                                    \
     fprintf(stderr,                                       \
             "Fatal error in %s on line %d: %s\n",         \
             __FILE__,                                     \
             __LINE__,                                     \
             msg);                                         \
     fflush(stderr);                                       \
     abort();                                              \
   } while (0)

 typedef enum {
     TCP = 0,
     UDP,
     PIPE
 } stream_type;

 static uv_loop_t* loop;

 static int server_closed;
 static stream_type serverType;
 static uv_tcp_t tcpServer;
 static uv_udp_t udpServer;
 static uv_pipe_t pipeServer;
 static uv_handle_t* server;

 static void after_write(uv_write_t* req, int status);
 static void after_read(uv_stream_t*, ssize_t nread, uv_buf_t buf);
 static void on_close(uv_handle_t* peer);
 static void on_server_close(uv_handle_t* handle);
 static void on_connection(uv_stream_t*, int status);
 static uv_buf_t echo_alloc(uv_handle_t* handle, size_t suggested_size);
 static void after_read(uv_stream_t* handle, ssize_t nread, uv_buf_t buf);
 static void after_read_2(uv_stream_t* handle, ssize_t nread, uv_buf_t buf);

 static void after_write(uv_write_t* req, int status) {
   write_req_t* wr;
   uv_err_t err;

   /* Free the read/write buffer and the request */
   wr = (write_req_t*) req;
   free(wr->buf.base);
   free(wr);

   if (status == 0)
     return;

   err = uv_last_error(loop);
   fprintf(stderr, "uv_write error: %s\n", uv_strerror(err));

   if (err.code == UV_ECANCELED)
     return;

   ASSERT(err.code == UV_EPIPE);
   uv_close((uv_handle_t*)req->handle, on_close);
 }


 static void after_shutdown(uv_shutdown_t* req, int status) {
   uv_close((uv_handle_t*)req->handle, on_close);
   free(req);
 }


 static void after_read(uv_stream_t* handle, ssize_t nread, uv_buf_t buf) {
   int i;
   write_req_t *wr;
   uv_shutdown_t* req;
   int r;

   if (nread < 0) {
     /* Error or EOF */
     ASSERT (uv_last_error(loop).code == UV_EOF);

     if (buf.base) {
       free(buf.base);
     }

     req = (uv_shutdown_t*) malloc(sizeof *req);
     uv_shutdown(req, handle, after_shutdown);

     return;
   }

   if (nread == 0) {
     /* Everything OK, but nothing read. */
     free(buf.base);
     return;
   }

   /*
    * Scan for the letter Q which signals that we should quit the server.
    * If we get QS it means close the stream.
    */
   if (!server_closed) {
     for (i = 0; i < nread; i++) {
       if (buf.base[i] == 'Q') {
         if (i + 1 < nread && buf.base[i + 1] == 'S') {
           free(buf.base);
           uv_close((uv_handle_t*)handle, on_close);
           return;
         } else {
           uv_close(server, on_server_close);
           server_closed = 1;
         }
       }
     }
   }

   wr = (write_req_t*) malloc(sizeof *wr);

   wr->buf = uv_buf_init(buf.base, nread);
   if (uv_write(&wr->req, handle, &wr->buf, 1, after_write)) {
     FATAL("uv_write failed");
   }

   r = uv_read_start(handle, echo_alloc, after_read_2);
   ASSERT(r == 0);
 }

 static void after_read_2(uv_stream_t* handle, ssize_t nread, uv_buf_t buf) {
   int i;
   write_req_t *wr;
   uv_shutdown_t* req;
   int r;

   if (nread < 0) {
     /* Error or EOF */
     ASSERT (uv_last_error(loop).code == UV_EOF);

     if (buf.base) {
       free(buf.base);
     }

     req = (uv_shutdown_t*) malloc(sizeof *req);
     uv_shutdown(req, handle, after_shutdown);

     return;
   }

   if (nread == 0) {
     /* Everything OK, but nothing read. */
     free(buf.base);
     return;
   }

   /*
    * Scan for the letter Q which signals that we should quit the server.
    * If we get QS it means close the stream.
    */
   if (!server_closed) {
     for (i = 0; i < nread; i++) {
       if (buf.base[i] == 'Q') {
         if (i + 1 < nread && buf.base[i + 1] == 'S') {
           free(buf.base);
           uv_close((uv_handle_t*)handle, on_close);
           return;
         } else {
           uv_close(server, on_server_close);
           server_closed = 1;
         }
       }
     }
   }

   wr = (write_req_t*) malloc(sizeof *wr);
   reversed(buf.base, nread);
   wr->buf = uv_buf_init(buf.base, nread);
   if (uv_write(&wr->req, handle, &wr->buf, 1, after_write)) {
     FATAL("uv_write failed");
   }

   r = uv_read_start(handle, echo_alloc, after_read);
   ASSERT(r == 0);
 }


 static void on_close(uv_handle_t* peer) {
   free(peer);
 }


 static uv_buf_t echo_alloc(uv_handle_t* handle, size_t suggested_size) {
   return uv_buf_init(malloc(suggested_size), suggested_size);
 }


 static void on_connection(uv_stream_t* server, int status) {
   uv_stream_t* stream;
   int r;

   if (status != 0) {
     fprintf(stderr, "Connect error %d\n",
         uv_last_error(loop).code);
   }
   ASSERT(status == 0);

   switch (serverType) {
   case TCP:
     stream = malloc(sizeof(uv_tcp_t));
     ASSERT(stream != NULL);
     r = uv_tcp_init(loop, (uv_tcp_t*)stream);
     ASSERT(r == 0);
     break;

   case PIPE:
     stream = malloc(sizeof(uv_pipe_t));
     ASSERT(stream != NULL);
     r = uv_pipe_init(loop, (uv_pipe_t*)stream, 0);
     ASSERT(r == 0);
     break;

   default:
     ASSERT(0 && "Bad serverType");
     abort();
   }

   /* associate server with stream */
   stream->data = server;

   r = uv_accept(server, stream);
   ASSERT(r == 0);

   r = uv_read_start(stream, echo_alloc, after_read);
   ASSERT(r == 0);
 }


 static void on_server_close(uv_handle_t* handle) {
   ASSERT(handle == server);
 }


 static void on_send(uv_udp_send_t* req, int status);


 static void on_recv(uv_udp_t* handle,
                     ssize_t nread,
                     uv_buf_t buf,
                     struct sockaddr* addr,
                     unsigned flags) {
   uv_udp_send_t* req;
   int r;

   ASSERT(nread > 0);
   ASSERT(addr->sa_family == AF_INET);

   req = malloc(sizeof(*req));
   ASSERT(req != NULL);

   r = uv_udp_send(req, handle, &buf, 1, *(struct sockaddr_in*)addr, on_send);
   ASSERT(r == 0);
 }


 static void on_send(uv_udp_send_t* req, int status) {
   ASSERT(status == 0);
   free(req);
 }


 static int tcp4_echo_start(int port) {
   struct sockaddr_in addr = uv_ip4_addr("0.0.0.0", port);
   int r;

   server = (uv_handle_t*)&tcpServer;
   serverType = TCP;

   r = uv_tcp_init(loop, &tcpServer);
   if (r) {
     /* TODO: Error codes */
     fprintf(stderr, "Socket creation error\n");
     return 1;
   }

   r = uv_tcp_bind(&tcpServer, addr);
   if (r) {
     /* TODO: Error codes */
     fprintf(stderr, "Bind error\n");
     return 1;
   }

   r = uv_listen((uv_stream_t*)&tcpServer, SOMAXCONN, on_connection);
   if (r) {
     /* TODO: Error codes */
     fprintf(stderr, "Listen error %s\n",
         uv_err_name(uv_last_error(loop)));
     return 1;
   }

   return 0;
 }

 int main()
 {
   loop = uv_default_loop();

   if (tcp4_echo_start(TEST_PORT))
     return 1;

   uv_run(loop, UV_RUN_DEFAULT);
   return 0;
 }