Boost C++ Libraries: Ticket #4690: boost::asio::ip::tcp::resolver fails to resolve query if service_name is empty

attachment set

Tue, 28 Sep 2010 16:05:17 GMT

attachment → resolv.cc

status changed; resolution set

chris_kohlhoff — Sat, 16 Oct 2010 08:59:58 GMT

status new → closed
resolution → worksforme

I assume this is some sort of linux system? I cannot reproduce any such error on mine.

Using the following slightly modified version of your testcase:

#include <iostream>
#include <boost/asio.hpp>
void print_result(const char* serv,
    boost::asio::ip::tcp::resolver::iterator iter,
    const boost::system::error_code& ec)
{
    if( ec )
        std::cerr << "service: '" << serv << "' FAIL: " << ec.message() << "\n";
    else
    {
        std::cerr << "service: '" << serv << "' OK\n";
        std::cerr << "endpoint: " << iter->endpoint() << "\n";
    }
}
void do_resolv(const char* serv)
{
    boost::asio::io_service io;
    boost::asio::ip::tcp::resolver resolver(io);
    boost::asio::ip::tcp::resolver::query q("127.0.0.1", serv);
    boost::system::error_code ec;
    boost::asio::ip::tcp::resolver::iterator iter = resolver.resolve(q,ec);
    print_result(serv, iter, ec);
}
int main()
{
    do_resolv("");
    do_resolv("12345");
    do_resolv("ftp");
    return 0;
}

I get the following output:

service: '' OK
endpoint: 127.0.0.1:0
service: '12345' OK
endpoint: 127.0.0.1:12345
service: 'ftp' OK
endpoint: 127.0.0.1:21

The problem may be specific to your target platform, in which case you will probably need to do some debugging to find out what is going on. Please reopen the bug if you find more information.

status changed; resolution deleted

Sat, 16 Oct 2010 12:40:36 GMT

status closed → reopened
resolution worksforme

gdb output of my program attached This is FreeBSD 9-CURRENT The same result under DragonFlyBSD, and some Linuxes

If it is not obvious to you from gdb output, what's the problem, I can try to look at boost sources when I have time. If you have suggestions how I can get more useful info, please let me know.

attachment set

Sat, 16 Oct 2010 12:42:07 GMT

attachment → resolv.gdb

gdb debug session

Sat, 16 Oct 2010 12:46:59 GMT

As you see from debug, empty servname is propagated down to getaddrinfo, which causes error. I think boost should replace empty string with something like "0" somewhere on the path to getaddrinfo.

chris_kohlhoff — Sat, 16 Oct 2010 13:16:02 GMT

(In [66022]) Pass NULL for servname rather than empty string, as per POSIX. Refs #4690.

chris_kohlhoff — Sat, 16 Oct 2010 13:16:50 GMT

Can you please try changeset [66022].

chris_kohlhoff — Mon, 18 Oct 2010 12:26:13 GMT

Problem reproduced and fix tested under FreeBSD 6.0.

status changed; resolution set

chris_kohlhoff — Mon, 18 Oct 2010 20:47:59 GMT

status reopened → closed
resolution → fixed

Fixed in [66080].