eventbuffer 只能读取 8 个字节的输入？

Question

我正在处理一些关于 libevent 的示例，并且运行遇到了从输入缓冲区读取任何超过 8 个字节的字符串的问题。我在本地网络上的两台计算机之间移动。这是我的简单 libevent 服务器代码：

#include <sys/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>

#include <event2/listener.h>
#include <event2/bufferevent.h>
#include <event2/buffer.h>

#define PORTNUM 8080

static void echo_read_cb(struct bufferevent *bev, void *ctx)
{
    struct evbuffer *input = bufferevent_get_input(bev);
    struct evbuffer *output = bufferevent_get_output(bev);

    size_t len = evbuffer_get_length(input);
    char *data = malloc(len);
    evbuffer_copyout(input, data, len);
    printf("We got some data: %s\n", data);
    free(data);
}

static void echo_event_cb(struct bufferevent *bev, short events, void *ctx)
{
    if (events & BEV_EVENT_ERROR) 
        perror("Error from bufferevent.");
    if (events & (BEV_EVENT_EOF | BEV_EVENT_ERROR)) {
        bufferevent_free(bev);
    }
}

static void accept_conn_cb(struct evconnlistener *listener, 
                           evutil_socket_t fd, struct sockaddr *addr,
                           int socklen, void *ctx)
{
    struct event_base *base = evconnlistener_get_base(listener);
    struct bufferevent *bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
    bufferevent_setcb(bev, echo_read_cb, NULL, echo_event_cb, NULL);
    bufferevent_enable(bev, EV_READ|EV_WRITE);
}

static void accept_error_cb(struct evconnlistener *listener, void *ctx) {
    struct event_base *base = evconnlistener_get_base(listener);
    int err = EVUTIL_SOCKET_ERROR();
    fprintf(stderr, "Got an error %d (%s) on the listener. "
            "Shutting down.\n", err, evutil_socket_error_to_string(err));
    event_base_loopexit(base, NULL);
}

int main(int argc, char **argv)
{
    struct event_base *base;
    struct evconnlistener *listener;
    struct sockaddr_in sin;

    base = event_base_new();
    if (!base) {
        puts("Couldn't open event base\n");
        return 1;
    }

    memset(&sin, 0, sizeof(sin));
    sin.sin_family = AF_INET;
    sin.sin_port = htons(PORTNUM);
    sin.sin_addr.s_addr = htonl(INADDR_ANY);

    listener = evconnlistener_new_bind(base, accept_conn_cb, NULL,
                                       LEV_OPT_CLOSE_ON_FREE|LEV_OPT_REUSEABLE,
                                       -1, (struct sockaddr *)&sin, 
                                       sizeof(sin));
    if (!listener) {
        perror("Couldn't create listener.\n");
        return 1;
    }

    evconnlistener_set_error_cb(listener, accept_error_cb);

    event_base_dispatch(base);
    return 0;
}

此程序继续运行而在本地网络上的另一台计算机上我运行使用常规网络的简单客户端程序：

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int main()
{
    struct sockaddr_in serv;
    memset(&serv, 0, sizeof(serv));
    serv.sin_family = AF_INET;
    serv.sin_port = htons(8080);
    inet_aton("192.168.1.155", &(serv.sin_addr));

    int SOCKET = socket(AF_INET, SOCK_STREAM, 0);
    connect(SOCKET, (struct sockaddr *)&serv, sizeof(struct sockaddr_in));

    const char *s = "Messagefromtheclient.";
    int n = send(SOCKET, s, sizeof(s), 0);
    close(SOCKET);
    return EXIT_SUCCESS;
}

我运行这个简单的客户端程序，它应该写入使用evbuffer制作的简单服务器并将数据输出到stdout。服务器写入 stdout：

> We got some data: Messagef

所以 data 只有 8 个字节，字符串的其余部分得到 t运行处理。谁能告诉我为什么？

Answer 1

您在此处传递指针的大小（在您的 64 位平台上恰好为 8）：

int n = send(SOCKET, s, sizeof(s), 0);
                        ^^^^^^^^^

您需要改为传递字符串中的字符数（+ 1 以包含 NUL 终止符）：

int n = send(SOCKET, s, strlen(s) + 1, 0);
                        ^^^^^^^^^^^^^

eventbuffer 只能读取 8 个字节的输入？

eventbuffer can only read 8 bytes on input?

c

sockets

libevent