[Libevent-users] How http client can send back message to server?

[Zulfiqer Sekender]

Hi,

I have to develop a simple http client which can communicate with a http 
server. 
The client is sending evhttp_make_request(). The server sends "HT:" heartbeat 
in 
response after certain time and when the client gets "HT:" each time it will 
send "HA:" as heartbeat acknowledgement. Transfering of "HT:" & "HA:" should go 
on.
I developed the following client program. It gets "HT:" and tries to send back 
"HA:". But server never gets the "HA:". 

I will highly appreciate any help regarding this. Please, let me know what 
wrong 
I am doing and how to do it correctly.  (Intentionally I left few commented out 
lines to show what else options I tried.) 


Please, please help me.
Thanks.

Here is the code:

 
#include <sys/types.h>
#include <sys/time.h>
#include <sys/queue.h>
#include <stdlib.h>
//#include <err.h>
#include <event.h>
#include <evhttp.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <time.h>
#include <pthread.h>
#include <string.h>
 
#define BUFSIZE 4096
#define SERVERADDR "15.172.175.61"
#define SERVERPORT 8070
#define SLEEP_MS 10
 
char buf[BUFSIZE];
 
int bytes_recvd = 0;
int chunks_recvd = 0;
int closed = 0;
int connected = 0;
 
// called per chunk received
void chunkcb(struct evhttp_request * req, void * arg)
{
    int s = evbuffer_remove( req->input_buffer, &buf, BUFSIZE );
    printf("Read %d bytes: %s\n", s, &buf);
    bytes_recvd += s;
    chunks_recvd++;
    if (strcmp(buf,"HT:") == 0)
    {    
      struct evbuffer *evbuff = NULL;
      evbuff = evbuffer_new();
      evbuffer_add_printf(evbuff,"HA:");
      evbuffer_add_printf(req->output_buffer,"HA:");
     // evhttp_send_reply_start(req, HTTP_OK, "Start");
      evhttp_send_reply_chunk(req, evbuff);
      // evhttp_send_reply_chunk(req,"3/r/nHA:/r/n");
      // evhttp_send_reply(req, HTTP_OK, "", evbuff);
      // evhttp_send_reply(req, HTTP_OK, "Response","3/r/nHA:/r/n" );
      // evhttp_send_reply(req, HTTP_OK, "Response",NULL);
      // evhttp_send_reply_end(req);
      evbuffer_free(evbuff);
    }
}
 
// gets called when request completes
void reqcb(struct evhttp_request * req, void * arg)
{
    closed++;
    printf("\nClosed.\n");
}
 
int main(int argc, char **argv)
{
    event_init();
    struct evhttp *evhttp_connection;
    struct evhttp_request *evhttp_request;
    char addr[16];
    char path[3200]; // eg: "/test/123"
    sprintf(&addr, "12.176.173.18");
    evhttp_connection = evhttp_connection_new(SERVERADDR, SERVERPORT);   
    if (evhttp_connection == NULL)
    {
            printf("New connection failed\n");
            break;
    }
    evhttp_connection_set_local_address(evhttp_connection, &addr);
    evhttp_set_timeout(evhttp_connection, 864000); // 10 day timeout
    evhttp_request = evhttp_request_new(reqcb, NULL);
    evhttp_request->chunk_cb = chunkcb;
    evhttp_request->chunked = 1; // Chunked
    evhttp_add_header(evhttp_request->output_headers, "Transfer-Encoding", 
"chunked");
    sprintf(&path, "/test/123");
    evhttp_make_request( evhttp_connection, evhttp_request, EVHTTP_REQ_POST, 
path );   

    evhttp_connection_set_timeout(evhttp_request->evcon, 864000);
    event_loop( EVLOOP_NONBLOCK );
    usleep(SLEEP_MS*1000);
    event_dispatch();
    return 0;
}