Well, you are using HTTP 1.0
In this version, after the server sends the response, it will close the
connection.
You may use HTTP 1.1 with "Connection: keep-alive" header, to signal the
server not to close the connection.
On Tue, Jul 21, 2020, 19:24 Bill Engelke <engelk...@bellsouth.net> wrote:
> I need code that will send a "heartbeat" to a web service (say, once per
> minute), and receive a response. This works fine with a browser, so I know
> the server is reachable and responding correctly. I have tried a vast
> number of different ways of doing this using libuv and c code, and so far,
> partial success at best. I have been able to connect to the server and send
> a request; but only the first request would work, and further sends would
> not make it to the server. In my most recent attempts, even the connection
> request stopped working. I don't know if the problem is my incorrect use of
> libuv, or something in the networking part that I don't understand. I have
> put the code into a single app for testing below; can anyone offer any
> suggestions??
>
> ```
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <uv.h>
> #include <string.h>
> #include <unistd.h>
>
> typedef struct {
> uv_write_t req;
> uv_buf_t buf;
> } write_req_t;
>
> static uv_tcp_t* socket_central;
> static struct sockaddr_in central_dest;
>
> static void alloc_buffer(uv_handle_t* handle, size_t suggested_size,
> uv_buf_t* buf) {
> buf->base = malloc(suggested_size);
> buf->len = suggested_size;
> }
>
> uv_loop_t *loop;
>
> ///// Callback for after TCP stream is closed //////////////////
> void on_close(uv_handle_t * handle)
> {
> printf("uv close triggered\n");
> }
>
> // process response from central server
> void proc_central_response(uv_stream_t *central, ssize_t nread, const
> uv_buf_t *buf)
> {
> printf("RESPONSE from Central Control; nread=%li\n",nread);
>
> printf("---------------------------------------------------------------\n");
> if (nread > 0) {
> printf("buf='%s'\n",buf->base);
>
> printf("---------------------------------------------------------------\n");
> }
> if (nread < 0) {
> if (nread != UV_EOF)
> fprintf(stderr, "Read error %s\n", uv_err_name(nread));
> free(buf->base);
> uv_close((uv_handle_t*) central, on_close);
> return;
> }
> //uv_close((uv_handle_t*) central, on_close);
> free(buf->base);
> return;
> }
>
> // now connected; send http POST
> void on_central_connect(uv_connect_t* connection, int status)
> {
> uv_stream_t* stream;
> uv_write_t write_req;
> printf("Connected to Central Contro, status = %il\n",status);
> if (status < 0) {
> fprintf(stderr, "Error in in connecting to Central Control %s\n",
> uv_strerror(status));
> // error!
> return;
> }
> printf(" - - - - Connect to Central Control - - - ;\n");
> // get the handle to the stream passed in connection
> stream = connection->handle;
>
> // make ready to receive response from Central
> uv_read_start((uv_stream_t*) stream, alloc_buffer,
> proc_central_response);
>
> // Now, prepare a heartbeat message to send to Central Control
>
> struct timeval timeout;
> char message[1024];
> timeout.tv_sec = 10; // if Central Host doesn't respond, we ignore
> timeout.tv_usec = 0; // and will try again after the pause time
> char tbuf[30];
> struct timeval tv;
> time_t curtime;
>
> char mytoken[75];
> strcpy(mytoken,"T12345XYZ"); // hard code this for now
>
> gettimeofday(&tv, NULL);
> curtime = tv.tv_sec;
> strftime(tbuf, 30, "%m-%d-%Y-%T.",localtime(&curtime));
> printf("Heartbeat TOD: '%s' %ld\n",tbuf,tv.tv_usec);
> // write message to go to host
> // message contains identity token and time stamp
> sprintf(message,"POST /apikey/%s-%s HTTP/1.0\r\n\r\n",mytoken,tbuf);
> uv_buf_t buf = uv_buf_init(message,strlen(message));
> int r1 = uv_write(&write_req, stream, &buf, 1, NULL);
> }
>
> void heartbeat(void *arg) {
> while(1==1)
> {
> printf("alloc socket\n");
> socket_central = (uv_tcp_t*)malloc(sizeof(uv_tcp_t));\
> printf("tcp init\n");
> uv_tcp_init(loop, socket_central);
> printf("alloc connection\n");
> uv_connect_t* connect = (uv_connect_t*)malloc(sizeof(uv_connect_t));
> uv_ip4_addr("192.168.1.67", 4000, ¢ral_dest);
> printf("CONNECT TO CENTRAL\n");
> uv_tcp_connect(connect, socket_central, (const struct
> sockaddr*)¢ral_dest, on_central_connect);
> printf("CONNECTION REQUEST DONE\n");
> printf("sleep start\n");
> sleep(5);
> printf("sleep done\n");
> }
> }
>
> int main() {
> printf("start\n");
> loop = uv_default_loop();
>
> printf("alloc socket\n");
> socket_central = (uv_tcp_t*)malloc(sizeof(uv_tcp_t));\
> printf("tcp init\n");
> uv_tcp_init(loop, socket_central);
>
> uv_thread_t hb_id;
> printf("start thread\n");
> uv_thread_create(&hb_id, heartbeat, NULL);
> printf("past thread start\n");
>
> uv_run(loop, UV_RUN_DEFAULT);
>
> sleep(10);
>
> printf("Now quitting.\n");
>
> uv_loop_close(loop);
> //free(loop);
> return 0;
> }
> ```
>
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