Start implementing and testing gethostbyname4_r

tests/common.rs

@@ -6,15 +6,23 @@
 #![allow(non_snake_case)]
 #![allow(dead_code)]
 
+use std::str::FromStr;
+
+include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
+
 use {
-    anyhow::{ensure, Result},
+    anyhow::{anyhow, bail, ensure, Result},
+    libc::{freeaddrinfo, gai_strerror, getaddrinfo},
+    nix::sys::socket::{SockaddrLike as _, SockaddrStorage},
     std::env,
-    std::ffi::CString,
+    std::ffi::{CStr, CString},
+    std::net::{IpAddr, Ipv4Addr, Ipv6Addr},
     std::path::PathBuf,
+    std::process::Command,
     std::sync::Once,
 };
 
-include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
+pub type Eai = EaiRetcode;
 
 static SETUP: Once = Once::new();
 
@@ -31,7 +39,7 @@ pub fn setup() -> Result<()> {
         });
 
         let db = CString::new("hosts").unwrap();
-        let resolvers = CString::new("malcontent [UNAVAIL=return] dns").unwrap();
+        let resolvers = CString::new("malcontent dns").unwrap();
         __nss_configure_lookup(db.as_ptr(), resolvers.as_ptr())
     };
 
@@ -43,3 +51,58 @@ pub fn setup() -> Result<()> {
 
     Ok(())
 }
+
+pub fn system_resolve(host: &str) -> Result<IpAddr> {
+    let process = Command::new("getent").arg("hosts").arg(host).output()?;
+    ensure!(
+        process.status.success(),
+        "Failed to run getent to check host IP"
+    );
+    let output = String::from_utf8(process.stdout)?;
+    let addr_string = output
+        .as_str()
+        .split(' ')
+        .next()
+        .ok_or(anyhow!("Unparseable output from getent"))?;
+    Ok(IpAddr::from_str(&addr_string)?)
+}
+
+pub fn convert_addrinfo(sa: &SockaddrStorage) -> Result<IpAddr> {
+    if let Some(addr) = sa.as_sockaddr_in() {
+        Ok(IpAddr::V4(Ipv4Addr::from(addr.ip())))
+    } else if let Some(addr) = sa.as_sockaddr_in6() {
+        Ok(IpAddr::V6(Ipv6Addr::from(addr.ip())))
+    } else {
+        bail!("addrinfo is not either an IPv4 or IPv6 address")
+    }
+}
+
+pub fn resolve_system_and_us(hostname: &str) -> Result<(IpAddr, IpAddr)> {
+    setup()?;
+    let ip_from_system = system_resolve(hostname)?;
+
+    let c_hostname = CString::new(hostname).unwrap();
+    unsafe {
+        let mut addr = std::ptr::null_mut();
+        let getaddrinfo_status = getaddrinfo(
+            c_hostname.as_ptr(),
+            std::ptr::null(),
+            std::ptr::null(),
+            &mut addr,
+        );
+
+        let error = CStr::from_ptr(gai_strerror(getaddrinfo_status));
+        assert_eq!(
+            getaddrinfo_status,
+            Eai::Success.0,
+            "Should have gotten hostname for {}, instead got {}",
+            hostname,
+            error.to_str().unwrap()
+        );
+        let addr_storage = SockaddrStorage::from_raw((*addr).ai_addr, Some((*addr).ai_addrlen))
+            .ok_or(anyhow!("Garbled addrinfo from getaddrinfo()"))?;
+        let ip_from_us = convert_addrinfo(&addr_storage)?;
+        freeaddrinfo(addr);
+        Ok((ip_from_system, ip_from_us))
+    }
+}

tests/integration_test.rs

@@ -4,32 +4,88 @@
 mod common;
 
 use {
-    anyhow::{bail, Result},
+    crate::common::Eai,
+    anyhow::Result,
     libc::{freeaddrinfo, gai_strerror, getaddrinfo},
+    std::net::{IpAddr, Ipv4Addr},
 };
 
 #[test]
-#[should_panic(expected = "not yet implemented")]
-fn nss_module_is_loaded() {
-    common::setup().unwrap();
+fn nss_module_is_loaded() -> Result<()> {
+    common::setup()?;
 
     let hostname = std::ffi::CString::new("gnome.org").unwrap();
     unsafe {
         let mut addr = std::ptr::null_mut();
-        match getaddrinfo(
+        let getaddrinfo_status = getaddrinfo(
             hostname.as_ptr(),
             std::ptr::null(),
             std::ptr::null(),
             &mut addr,
-        ) {
-            0 => freeaddrinfo(addr),
-            status => {
-                let error = std::ffi::CStr::from_ptr(gai_strerror(status));
-                panic!(
-                    "Unable to resolve hostname, getaddrinfo returned {}",
-                    error.to_str().unwrap()
-                )
-            }
-        }
+        );
+
+        let error = std::ffi::CStr::from_ptr(gai_strerror(getaddrinfo_status));
+        assert_eq!(
+            getaddrinfo_status,
+            0,
+            "Unable to resolve hostname, getaddrinfo failed: {}",
+            error.to_str().unwrap()
+        );
+        freeaddrinfo(addr);
     };
+
+    Ok(())
+}
+
+#[test]
+fn application_dns_is_nxdomain() -> Result<()> {
+    common::setup()?;
+
+    let hostname = std::ffi::CString::new("use-application-dns.net").unwrap();
+    unsafe {
+        let mut addr = std::ptr::null_mut();
+        let getaddrinfo_status = getaddrinfo(
+            hostname.as_ptr(),
+            std::ptr::null(),
+            std::ptr::null(),
+            &mut addr,
+        );
+
+        let error = std::ffi::CStr::from_ptr(gai_strerror(getaddrinfo_status));
+        assert_eq!(
+            getaddrinfo_status,
+            Eai::NoName.0,
+            "Should have gotten no hostname (NXDOMAIN), instead got {}",
+            error.to_str().unwrap()
+        );
+        freeaddrinfo(addr);
+    };
+    Ok(())
+}
+
+#[test]
+
+fn wikipedia_is_unrestricted() -> Result<()> {
+    let (system_addr, our_addr) = common::resolve_system_and_us("wikipedia.org")?;
+    assert_eq!(system_addr, our_addr);
+    Ok(())
+}
+
+#[test]
+#[ignore]
+fn adultsite_is_restricted() -> Result<()> {
+    let (system_addr, our_addr) = common::resolve_system_and_us("pornhub.com")?;
+    assert_ne!(system_addr, our_addr);
+    assert_eq!(our_addr, IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)));
+    Ok(())
+}
+
+#[test]
+#[ignore]
+fn root_user_bypasses_restrictions() -> Result<()> {
+    // TODO fake root
+
+    let (system_addr, our_addr) = common::resolve_system_and_us("pornhub.com")?;
+    assert_eq!(system_addr, our_addr);
+    Ok(())
 }