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Receiving fd with Zig!

master
Philippe Pittoli 2023-01-02 08:36:14 +01:00
parent 14509b8d28
commit b43fd57704
1 changed files with 208 additions and 0 deletions

208
zig-impl/misc/rcv-fd.zig Normal file
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const std = @import("std");
const testing = std.testing;
const net = std.net;
const fmt = std.fmt;
const os = std.os;
const mem = std.mem;
const print = std.debug.print;
const Cmsghdr = @import("./cmsghdr.zig").Cmsghdr;
const system = std.os.system;
const socket_t = std.os.socket_t;
const msghdr = system.msghdr;
const builtin = @import("builtin");
const windows = std.os.windows;
const errno = std.os.errno;
const unexpectedErrno = std.os.unexpectedErrno;
const SendMsgError = std.os.SendMsgError;
pub fn recvmsg(
/// The file descriptor of the sending socket.
sockfd: socket_t,
/// Message header and iovecs
msg: msghdr,
flags: u32,
) SendMsgError!usize {
while (true) {
var m = msg;
const rc = system.recvmsg(sockfd, @ptrCast(*std.x.os.Socket.Message, &m), @intCast(c_int, flags));
if (builtin.os.tag == .windows) {
if (rc == windows.ws2_32.SOCKET_ERROR) {
switch (windows.ws2_32.WSAGetLastError()) {
.WSAEACCES => return error.AccessDenied,
.WSAEADDRNOTAVAIL => return error.AddressNotAvailable,
.WSAECONNRESET => return error.ConnectionResetByPeer,
.WSAEMSGSIZE => return error.MessageTooBig,
.WSAENOBUFS => return error.SystemResources,
.WSAENOTSOCK => return error.FileDescriptorNotASocket,
.WSAEAFNOSUPPORT => return error.AddressFamilyNotSupported,
.WSAEDESTADDRREQ => unreachable, // A destination address is required.
.WSAEFAULT => unreachable, // The lpBuffers, lpTo, lpOverlapped, lpNumberOfBytesSent, or lpCompletionRoutine parameters are not part of the user address space, or the lpTo parameter is too small.
.WSAEHOSTUNREACH => return error.NetworkUnreachable,
// TODO: WSAEINPROGRESS, WSAEINTR
.WSAEINVAL => unreachable,
.WSAENETDOWN => return error.NetworkSubsystemFailed,
.WSAENETRESET => return error.ConnectionResetByPeer,
.WSAENETUNREACH => return error.NetworkUnreachable,
.WSAENOTCONN => return error.SocketNotConnected,
.WSAESHUTDOWN => unreachable, // The socket has been shut down; it is not possible to WSASendTo on a socket after shutdown has been invoked with how set to SD_SEND or SD_BOTH.
.WSAEWOULDBLOCK => return error.WouldBlock,
.WSANOTINITIALISED => unreachable, // A successful WSAStartup call must occur before using this function.
else => |err| return windows.unexpectedWSAError(err),
}
} else {
return @intCast(usize, rc);
}
} else {
switch (errno(rc)) {
.SUCCESS => return @intCast(usize, rc),
.ACCES => return error.AccessDenied,
.AGAIN => return error.WouldBlock,
.ALREADY => return error.FastOpenAlreadyInProgress,
.BADF => unreachable, // always a race condition
.CONNRESET => return error.ConnectionResetByPeer,
.DESTADDRREQ => unreachable, // The socket is not connection-mode, and no peer address is set.
.FAULT => unreachable, // An invalid user space address was specified for an argument.
.INTR => continue,
.INVAL => unreachable, // Invalid argument passed.
.ISCONN => unreachable, // connection-mode socket was connected already but a recipient was specified
.MSGSIZE => return error.MessageTooBig,
.NOBUFS => return error.SystemResources,
.NOMEM => return error.SystemResources,
.NOTSOCK => unreachable, // The file descriptor sockfd does not refer to a socket.
.OPNOTSUPP => unreachable, // Some bit in the flags argument is inappropriate for the socket type.
.PIPE => return error.BrokenPipe,
.AFNOSUPPORT => return error.AddressFamilyNotSupported,
.LOOP => return error.SymLinkLoop,
.NAMETOOLONG => return error.NameTooLong,
.NOENT => return error.FileNotFound,
.NOTDIR => return error.NotDir,
.HOSTUNREACH => return error.NetworkUnreachable,
.NETUNREACH => return error.NetworkUnreachable,
.NOTCONN => return error.SocketNotConnected,
.NETDOWN => return error.NetworkSubsystemFailed,
else => |err| return unexpectedErrno(err),
}
}
}
}
fn disconnect(stream: *net.StreamServer) void { stream.close(); }
fn server_init() net.StreamServer {
// no reuse_address and default kernel_backlog
return net.StreamServer.init(.{});
}
fn waiting_for_connection(stream: *net.StreamServer
, path: []const u8) !net.StreamServer.Connection {
var address = try net.Address.initUnix(path);
try stream.listen(address);
return stream.accept();
}
fn remove_unix_socket(path: []const u8) void {
std.fs.deleteFileAbsolute(path) catch |err| switch(err) {
else => { print("error: {}\n", .{err}); }
};
}
const SCM_RIGHTS: c_int = 1;
fn send_msg(sock: os.socket_t, msg: []const u8, fd: os.fd_t) void {
var iov = [_]os.iovec_const{
.{
.iov_base = msg.ptr,
.iov_len = msg.len,
},
};
var cmsg = Cmsghdr(os.fd_t).init(.{
.level = os.SOL.SOCKET,
.@"type" = SCM_RIGHTS,
.data = fd,
});
const len = os.sendmsg(sock, .{
.name = undefined,
.namelen = 0,
.iov = &iov,
.iovlen = iov.len,
.control = &cmsg,
.controllen = @sizeOf(@TypeOf(cmsg)),
.flags = 0,
}, 0) catch |err| {
print("error sendmsg failed with {s}", .{@errorName(err)});
return;
};
if (len != msg.len) {
// we don't have much choice but to exit here
// log.err(@src(), "expected sendmsg to return {} but got {}", .{msg.len, len});
print("expected sendmsg to return {} but got {}", .{msg.len, len});
os.exit(0xff);
}
}
fn receive_msg(sock: os.socket_t) !os.fd_t {
var buffer: [100]u8 = undefined;
var iov = [1]os.iovec{
.{
.iov_base = buffer[0..],
.iov_len = buffer.len,
},
};
var cmsg = Cmsghdr(os.fd_t).init(.{
.level = os.SOL.SOCKET,
.@"type" = SCM_RIGHTS,
.data = undefined,
});
var msg: std.os.msghdr = .{
.name = undefined,
.namelen = 0,
.iov = &iov,
.iovlen = iov.len,
.control = &cmsg,
.controllen = @sizeOf(@TypeOf(cmsg)),
.flags = 0,
};
const len = recvmsg(sock, msg, 0) catch |err| {
print("error sendmsg failed with {s}", .{@errorName(err)});
return 0;
};
print("received {} bytes, fd is {}\n", .{len, @as(i32, cmsg.dataPtr().*)});
print("iov base {s}\n", .{iov[0].iov_base[0..iov[0].iov_len - 1]});
return @as(i32, cmsg.dataPtr().*);
}
fn add_line_from_fd(fd: i32) !void {
// var f = std.fs.File {.handle = fd};
// defer f.close();
_ = try std.os.write(fd, "hello this is another line\n");
std.os.close(fd);
}
pub fn main() !u8 {
var path = "/tmp/.TEST_USOCK";
print("Init UNIX server to {s}...\n", .{path});
var stream = server_init();
defer stream.deinit();
print("Waiting for a connection...\n", .{});
var connection = try waiting_for_connection(&stream, path);
defer remove_unix_socket(path);
print("Someone is connected! Receiving a file descriptor...\n", .{});
var fd = try receive_msg(connection.stream.handle);
print("FD received, writing a line into the file...\n", .{});
try add_line_from_fd(fd);
print("Disconnection...\n", .{});
disconnect(&stream);
print("Disconnected!\n", .{});
return 0;
}