shadow_rs/host/syscall/handler/
shadow.rs

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1use linux_api::errno::Errno;
2use shadow_shim_helper_rs::syscall_types::ForeignPtr;
3
4use crate::core::worker::Worker;
5use crate::host::syscall::handler::{SyscallContext, SyscallHandler};
6use crate::host::syscall::types::ForeignArrayPtr;
7use crate::utility::case_insensitive_eq;
8
9impl SyscallHandler {
10    log_syscall!(shadow_yield, /* rv */ std::ffi::c_int);
11    pub fn shadow_yield(_ctx: &mut SyscallContext) -> Result<(), Errno> {
12        Ok(())
13    }
14
15    log_syscall!(shadow_init_memory_manager, /* rv */ std::ffi::c_int);
16    pub fn shadow_init_memory_manager(ctx: &mut SyscallContext) -> Result<(), Errno> {
17        if !ctx.objs.host.params.use_mem_mapper {
18            log::trace!("Not initializing memory mapper");
19            return Ok(());
20        }
21
22        log::trace!("Initializing memory mapper");
23
24        let mut memory_manager = ctx.objs.process.memory_borrow_mut();
25        if !memory_manager.has_mapper() {
26            memory_manager.init_mapper(ctx.objs)
27        }
28
29        Ok(())
30    }
31
32    log_syscall!(
33        shadow_hostname_to_addr_ipv4,
34        /* rv */ std::ffi::c_int,
35        /* name_ptr */ *const std::ffi::c_char,
36        /* name_len */ u64,
37        /* addr_ptr */ *const std::ffi::c_void,
38        /* addr_len */ u64,
39    );
40    pub fn shadow_hostname_to_addr_ipv4(
41        ctx: &mut SyscallContext,
42        name_ptr: ForeignPtr<std::ffi::c_char>,
43        name_len: u64,
44        addr_ptr: ForeignPtr<()>,
45        addr_len: u64,
46    ) -> Result<(), Errno> {
47        log::trace!("Handling custom syscall shadow_hostname_to_addr_ipv4");
48
49        let name_len: usize = name_len.try_into().unwrap();
50        let addr_len: usize = addr_len.try_into().unwrap();
51
52        if addr_len < std::mem::size_of::<u32>() {
53            log::trace!("Invalid addr_len {addr_len}, returning EINVAL");
54            return Err(Errno::EINVAL);
55        }
56
57        // TODO: Don't add 1 byte to length (if the application gave us a length of X bytes, don't
58        // read more than X bytes). This might not be valid memory. I'm guessing we do this now to
59        // avoid needing to allocate a new `CString` with a NUL byte when calling into the C DNS
60        // code. But in the future when the DNS code is in rust, we won't need NUL-terminated
61        // strings.
62
63        let name_ptr = name_ptr.cast::<u8>();
64        // add one byte to the length and hope that it contains a NUL
65        let name_ptr = ForeignArrayPtr::new(name_ptr, name_len + 1);
66        let addr_ptr = addr_ptr.cast::<u32>();
67
68        let mut mem = ctx.objs.process.memory_borrow_mut();
69
70        let lookup_name_ref = mem.memory_ref_prefix(name_ptr)?;
71        let lookup_name = lookup_name_ref.get_cstr()?;
72        let lookup_name_bytes = lookup_name.to_bytes();
73
74        if case_insensitive_eq(lookup_name_bytes, &b"localhost"[..]) {
75            let addr = u32::from(std::net::Ipv4Addr::LOCALHOST);
76            mem.write(addr_ptr, &addr.to_be())?;
77            log::trace!("Returning loopback address for localhost");
78            return Ok(());
79        }
80
81        // TODO: why do we truncate at `NI_MAXHOST`?
82        let max_len = libc::NI_MAXHOST.try_into().unwrap();
83        let host_name = ctx.objs.host.info().name.as_bytes();
84        let host_name = &host_name[..std::cmp::min(host_name.len(), max_len)];
85        let lookup_name_bytes =
86            &lookup_name_bytes[..std::cmp::min(lookup_name_bytes.len(), max_len)];
87
88        let addr = if case_insensitive_eq(lookup_name_bytes, host_name) {
89            log::trace!("Using default address for my own hostname {lookup_name:?}");
90            Some(ctx.objs.host.default_ip())
91        } else {
92            log::trace!("Looking up name {lookup_name:?}");
93            Worker::resolve_name_to_ip(lookup_name)
94        };
95
96        let Some(addr) = addr else {
97            log::trace!("Unable to find address for name {lookup_name:?}");
98            // return EFAULT like gethostname
99            return Err(Errno::EFAULT);
100        };
101
102        log::trace!("Found address {addr} for name {lookup_name:?}");
103
104        let addr = u32::from(addr);
105        mem.write(addr_ptr, &addr.to_be())?;
106
107        Ok(())
108    }
109}
shadow_rs/host/syscall/handler/shadow.rs

shadow_rs/host/syscall/handler/
shadow.rs
