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[Libevent-users] Re: recv() event not triggering



Pleas ignore the exit(0) in the fail connect() condition. I have removed it since non blocking connect will return <0 anyways. still the output I get is
connecting failed
DISPATCHING
IN CB CONNECT
IN CB CHECKSTATUS
ADDED READ EVENT


On Wed, Feb 12, 2020 at 10:34 PM Salman Ahmed <salman.isd@xxxxxxxxx> wrote:
Hello,
I am trying to connect to the local openvpn client over its managment socket and query its state/status.

I have implemented the follow program with libevent support.


#include
<stdio.h> #include <stdlib.h> #include <sys/socket.h> #include <arpa/inet.h> #include <event2/event.h> #include <fcntl.h> #include <string.h> char message[1000], server_reply[2000]; struct event *ev, *ev1, *ev2; void cb_func_hold_release(evutil_socket_t fd, short what, void *arg) { int sock = *(int *)arg; struct timeval one_seconds = {1,0}; printf("IN CB CONNECT\n"); sprintf (message, "hold release\n"); if (send (sock, message, strlen (message), 0) < 0) { printf("send failed\n"); } event_add(ev1, NULL); } void cb_func_write(evutil_socket_t fd, short what, void *arg) { int sock = *(int *)arg; printf("IN CB CHECKSTATUS\n"); sprintf (message, "status\n"); if (send (sock, message, strlen (message), 0) < 0) { printf("send failed\n"); } /* int reclen = recv (sock, server_reply, 2000, 0); if (reclen < 0) { printf("recving failed"); } else { if (reclen > 1) { server_reply[reclen-1] = '\0'; } printf("SERVER REPLT< %s\n", server_reply); } if (strstr(message, "CONNECTED")) { printf("VPN CONNECTED"); } */ event_add(ev2, NULL); if (event_pending(ev2,EV_READ|EV_PERSIST, NULL)) { printf("ADDED READ EVENT\n"); } } void cb_func_read(evutil_socket_t fd, short what, void *arg) { int sock = *(int *)arg; printf("IN CB READ\n"); int reclen = recv (sock, server_reply, 2000, 0); if (reclen < 0) { printf("recving failed"); } else { if (reclen > 1) { server_reply[reclen-1] = '\0'; } printf("SERVER REPLY %s\n", server_reply); } if (strstr(message, "CONNECTED")) { printf("VPN CONNECTED"); } } int main(void) { int flags; int mgmretry = 0; int sock = 0; struct sockaddr_in server; struct timeval five_seconds = {1,0}; struct event_base *base = event_base_new(); ev = event_new(base, sock, EV_TIMEOUT, cb_func_hold_release, &sock); ev1 = event_new(base, sock, EV_WRITE, cb_func_write, &sock); ev2 = event_new(base, sock, EV_READ, cb_func_read, &sock); sock = socket (AF_INET, SOCK_STREAM, 0); if (sock == -1) { printf("COUILD NOT CREATE SOCKET\n"); exit(0); } evutil_make_socket_nonblocking(sock);
server
.sin_addr.s_addr = inet_addr("127.0.0.1"); server.sin_family = AF_INET; server.sin_port = htons (12345); if (connect (sock, (struct sockaddr *)&server, sizeof (server)) < 0) { printf("connecting failed\n"); exit(0); } event_add(ev, &five_seconds); printf("DISPATCHING\n"); event_base_dispatch(base); }

The issue is the the read callback "cb_func_read" is not being triggered. My expectation is that after I send the "status" message to the vpn from cb_func_write(), there is some data sent back which should trigger the read callback but that's not happening.

If I recv() directly after send() in the write callback(the commented portion) I can print the response sent from openvpn so the communication between these two are working.