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// file : bbot/agent/tftp.cxx -*- C++ -*-
// license : TBC; see accompanying LICENSE file
#include <bbot/agent/tftp.hxx>
#include <arpa/inet.h> // htonl()
#include <netinet/in.h> // sockaddr_in
#include <sys/socket.h>
#include <sys/select.h>
#include <cstring> // memset()
#include <bbot/agent/agent.hxx>
using namespace std;
using namespace butl;
namespace bbot
{
tftp_server::
tftp_server (const string& map, uint16_t port)
{
int fd (socket (AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0));
if (fd == -1)
throw_system_error (errno);
fd_.reset (fd);
// Bind to ephemeral port.
//
sockaddr_in addr;
memset (&addr, 0, sizeof (addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = htonl (INADDR_ANY);
addr.sin_port = htons (port);
// Not to confuse with std::bind().
//
if (::bind (fd,
reinterpret_cast<sockaddr*> (&addr),
sizeof (sockaddr_in)) == -1)
throw_system_error (errno);
// Create the map file.
//
map_ = auto_rmfile (path::temp_path ("bbot-agent-tftp-map"));
ofdstream ofs (map_.path);
ofs << map << endl;
ofs.close ();
}
uint16_t tftp_server::
port () const
{
sockaddr_in addr;
socklen_t size (sizeof (addr));
if (getsockname (fd_.get (),
reinterpret_cast<sockaddr*> (&addr),
&size) == -1)
throw_system_error (errno);
assert (size == sizeof (addr));
return ntohs (addr.sin_port);
}
bool tftp_server::
serve (size_t& sec, size_t inc)
{
tracer trace ("tftp_server::serve");
if (inc == 0 || inc > sec)
inc = sec;
int fd (fd_.get ());
// Note: Linux updates the timeout value which we rely upon.
//
timeval timeout {static_cast<long> (inc), 0};
fd_set rd;
FD_ZERO (&rd);
for (;;)
{
FD_SET (fd, &rd);
int r (select (fd + 1, &rd, nullptr, nullptr, &timeout));
if (r == -1)
{
if (errno == EINTR)
continue;
throw_system_error (errno);
}
else if (r == 0) // Timeout.
{
sec -= inc;
return false;
}
if (FD_ISSET (fd, &rd))
{
// The inetd "protocol" is to pass the socket as stdin/stdout file
// descriptors.
//
// Notes/issues:
//
// 1. Writes diagnostics to syslog.
//
run_io (trace,
fddup (fd),
fddup (fd),
2,
"sudo", // Required for --secure (chroot).
"/usr/sbin/in.tftpd", // Standard installation location.
"--verbosity", 1, // Verbosity level.
"--timeout", 1, // Wait for more requests.
"--permissive", // Use inherited umask.
"--create", // Allow creating new files (PUT).
"--map-file", map_.path, // Path remapping rules.
"--user", uname, // Run as our effective user.
"--secure", // Chroot to data directory.
ops.tftp ());
// This is not really accurate since tftpd will, for example, serve
// an upload request until it is complete. But it's close anough for
// our needs.
//
sec -= (inc - static_cast<size_t> (timeout.tv_sec));
return true;
}
}
}
}
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