How to detect when THttpServer fails to start?

ROOT
1

How do I detect that THttpServer failed to start and is not actually working? For example, I call new THttpServer(“http:127.0.0.1:80?cors”) and as expected, it fails, but all I get is an error message printed to the terminal (Error in THttpEngine::Log: cannot bind to 127.0.0.1:80: 13 (Permission denied)). I would like to detect this failure and stop my application (since it is not actually working). I see that deep down set_ports_option() in civetweb.c sets so.sock to INVALID_SOCKET and returns 0, how is this error condition propagated to THttpServer level?

2

The error code path seems to be:
bind() syscall fails
set_ports_option() returns 0
mg_start2() returns NULL
mg_start() returns NULL
TCivetweb::Create() returns kFalse
THttpEngine::Create() returns kFalse
THttpServer::CreateEngine() returns fFalse, adds nothing to fEngines
THttpServer::ctor ignores the error return from CreateEngine(). WTH!

3

This works:
if (httpPort) {
#ifdef HAVE_THTTP_SERVER
char str[256];
snprintf(str, sizeof(str), “http:127.0.0.1:%d?cors”, httpPort);
THttpServer *s = new THttpServer(str);
if (!s->IsAnyEngine()) {
fprintf(stderr,“ERROR: Cannot start web server on http port %d, see previous error message.\n”, httpPort);
exit(1);
}

4

Hi @dd1,

thank you for your question. Maybe @linev could help?

Cheers,

Marta

5

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.

6

Hi,

You can use CreateEngine method of THttpServer. Like:

auto serv = new THttpServer("");
if (!serv->CreateEngine("http:127.0.0.1:80?cors"))
   printf("Fail to start server on port 80\n");

Regards,
Sergey

P.S. Sorry for some delay.