libevent bufferevent output size

 /*
 *
 * Demonstrates problematic libevent behavior while trying to constrain size of output buffer
 *
 * Compile with:
 * gcc -Wall `pkg-config --cflags --libs libevent` -o server server.c
 *
 * Run with:
 * ./server
 *
 * In another terminal:
 * yes | nc localhost 6565
 *
 * Notice the output the server produces - and after a while the output callback is no longer called
 *
 * Mina Naguib, 2011
 */

#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <time.h>

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

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

#define PORT 6565
#define MAX_INPUT_BUFFER_SIZE 8192
#define MAX_OUTPUT_BUFFER_SIZE 10240

char *
now() {
    time_t now = time(NULL);
    char *n = ctime(&now);
    char *temp;

    if ((temp = strchr(n, '\n'))) *temp = '\0';

    return n;
}

void
handle_client_buffer_in(struct bufferevent *bev, void *hint) {
    struct evbuffer *input = bufferevent_get_input(bev);
    struct evbuffer *output = bufferevent_get_output(bev);
    size_t inlen = evbuffer_get_length(input), outlen = evbuffer_get_length(output);
    size_t len;
    char *line;
    char *response;

    printf("[%s] BEV IN CALLED.  BEV LENGTHS: IN [%d] OUT [%d]\n", now(), (int)inlen, (int)outlen);

    if (outlen >= MAX_OUTPUT_BUFFER_SIZE) {
        // Libevent will make sure the input buffer doesn't keep growing, but it's up to us
        // to not write too much to the output buffer. We do that by refusing to drain the input buffer
        return;
    }

    while ((line = evbuffer_readln(input, &len, EVBUFFER_EOL_CRLF))) {
        free(line);
        response = "WELCOME TO MIAMI\n";
        len = strlen(response);
        evbuffer_add(output, response, len);
    }

}

void
handle_client_buffer_out(struct bufferevent *bev, void *hint) {
    struct evbuffer *input = bufferevent_get_input(bev);
    struct evbuffer *output = bufferevent_get_output(bev);
    size_t inlen = evbuffer_get_length(input), outlen = evbuffer_get_length(output);

    printf("[%s] BEV OUT CALLED.  BEV LENGTHS: IN [%d] OUT [%d]\n", now(), (int)inlen, (int)outlen);

    // We can now start reading again
    if (inlen > 0) handle_client_buffer_in(bev, hint);

}

void
handle_client_buffer_evt(struct bufferevent *bev, short revents, void *hint) {

    if (revents & BEV_EVENT_ERROR) {
        printf("Client error: %s\n", strerror(errno));
        bufferevent_free(bev);
    }
    else if (revents & BEV_EVENT_TIMEOUT) {
        printf("Client timed out\n");
        bufferevent_free(bev);
    }
    else if (revents & BEV_EVENT_EOF) {
        printf("Client disconnected\n");
        bufferevent_free(bev);
    }
    else {
        printf("Spurious event from client: %d\n", revents);
        bufferevent_free(bev);
    }
}

void
handle_new_client(struct evconnlistener *listener, evutil_socket_t client_fd, struct sockaddr *addr, int len, void *ptr) {

    struct bufferevent * bev;

    printf("Client connected\n");

    bev = bufferevent_socket_new(evconnlistener_get_base(listener), client_fd, BEV_OPT_CLOSE_ON_FREE);
    bufferevent_setcb(
            bev,
            handle_client_buffer_in,
            handle_client_buffer_out,
            handle_client_buffer_evt,
            NULL
            );
    bufferevent_setwatermark(bev, EV_READ, 0, MAX_INPUT_BUFFER_SIZE);
    bufferevent_enable(bev, EV_READ);


}

int main(int argc, char ** argv) {

    struct evconnlistener * server_listener;
    struct event_base *eb = NULL;
    struct sockaddr_in sa;

    eb = event_base_new();

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

    server_listener = evconnlistener_new_bind(
            eb,
            handle_new_client,
            NULL,
            LEV_OPT_CLOSE_ON_FREE | LEV_OPT_REUSEABLE,
            -1,
            (struct sockaddr *)&sa,
            sizeof(sa)
            );

    if (server_listener != NULL) {
        printf("Server listening on port %d\n", PORT);
        event_base_dispatch(eb);
        return 0;
    }
    else {
        printf("Could not get server going...\n");
        return 1;
    }

}