mpd/src/net/Resolver.cxx
2024-04-10 13:36:05 +02:00

127 lines
2.9 KiB
C++

// SPDX-License-Identifier: BSD-2-Clause
// Copyright CM4all GmbH
// author: Max Kellermann <mk@cm4all.com>
#include "Resolver.hxx"
#include "AddressInfo.hxx"
#include "HostParser.hxx"
#include "lib/fmt/RuntimeError.hxx"
#include "util/CharUtil.hxx"
#ifdef _WIN32
#include <ws2tcpip.h>
#else
#include <sys/socket.h>
#include <netdb.h>
#include <net/if.h>
#endif
#include <cstring>
#include <stdio.h>
AddressInfoList
Resolve(const char *node, const char *service,
const struct addrinfo *hints)
{
struct addrinfo *ai;
int error = getaddrinfo(node, service, hints, &ai);
if (error != 0) {
#ifdef _WIN32
const char *msg = gai_strerrorA(error);
#else
const char *msg = gai_strerror(error);
#endif
throw FmtRuntimeError("Failed to resolve {:?}:{:?}: {}",
node == nullptr ? "" : node,
service == nullptr ? "" : service,
msg);
}
return AddressInfoList(ai);
}
static inline bool
ai_is_passive(const struct addrinfo *ai)
{
return ai == nullptr || (ai->ai_flags & AI_PASSIVE) != 0;
}
#ifndef _WIN32
/**
* Check if there is an interface name after '%', and if so, replace
* it with the interface index, because getaddrinfo() understands only
* the index, not the name (tested on Linux/glibc).
*/
static void
FindAndResolveInterfaceName(char *host, size_t size)
{
char *percent = std::strchr(host, '%');
if (percent == nullptr || percent + 64 > host + size)
return;
char *interface = percent + 1;
if (!IsAlphaASCII(*interface))
return;
const unsigned i = if_nametoindex(interface);
if (i == 0)
throw FmtRuntimeError("No such interface: {}", interface);
sprintf(interface, "%u", i);
}
#endif
AddressInfoList
Resolve(const char *host_and_port, int default_port,
const struct addrinfo *hints)
{
const char *host, *port;
char buffer[256], port_string[16];
if (host_and_port != nullptr) {
const auto eh = ExtractHost(host_and_port);
if (eh.HasFailed())
throw std::runtime_error("Failed to extract host name");
if (eh.host.size() >= sizeof(buffer))
throw std::runtime_error("Host name too long");
*std::copy(eh.host.begin(), eh.host.end(), buffer) = 0;
host = buffer;
#ifndef _WIN32
FindAndResolveInterfaceName(buffer, sizeof(buffer));
#endif
port = eh.end;
if (*port == ':') {
/* port specified */
++port;
} else if (*port == 0) {
/* no port specified */
snprintf(port_string, sizeof(port_string), "%d", default_port);
port = port_string;
} else
throw std::runtime_error("Garbage after host name");
if (ai_is_passive(hints) && strcmp(host, "*") == 0)
host = nullptr;
} else {
host = nullptr;
snprintf(port_string, sizeof(port_string), "%d", default_port);
port = port_string;
}
return Resolve(host, port, hints);
}
AddressInfoList
Resolve(const char *host_port, unsigned default_port, int flags, int socktype)
{
const auto hints = MakeAddrInfo(flags, AF_UNSPEC, socktype);
return Resolve(host_port, default_port, &hints);
}