feat: try to dynamically load libc.so on Android

Cargo.toml

@@ -13,6 +13,10 @@ license = "MIT"
 [dependencies]
 libc = "0.2"
 
+[target.'cfg(target_os = "android")'.dependencies]
+dlopen = "0.1.8"
+once_cell = "1.17.1"
+
 [target.'cfg(windows)'.dependencies]
 memalloc = "0.1.0"
 

src/interface/android.rs

@@ -0,0 +1,64 @@
+use once_cell::sync::OnceCell;
+
+fn load_symbol<T>(sym: &'static str) -> Option<T> {
+    const LIB_NAME: &str = "libc.so";
+
+    println!("loading symbol: {} from {}", sym, LIB_NAME);
+    match dlopen::raw::Library::open(LIB_NAME) {
+        Ok(lib) => match unsafe { lib.symbol::<T>(sym) } {
+            Ok(val) => Some(val),
+            Err(err) => {
+                eprintln!("failed to load symbol {} from {}: {:?}", sym, LIB_NAME, err);
+                None
+            }
+        },
+        Err(err) => {
+            eprintln!("failed to load {}: {:?}", LIB_NAME, err);
+            None
+        }
+    }
+}
+
+fn get_getifaddrs() -> Option<unsafe extern "C" fn(*mut *mut libc::ifaddrs) -> libc::c_int> {
+    static INSTANCE: OnceCell<
+        Option<unsafe extern "C" fn(*mut *mut libc::ifaddrs) -> libc::c_int>,
+    > = OnceCell::new();
+
+    *INSTANCE.get_or_init(|| load_symbol("getifaddrs"))
+}
+
+fn get_freeifaddrs() -> Option<unsafe extern "C" fn(*mut libc::ifaddrs)> {
+    static INSTANCE: OnceCell<Option<unsafe extern "C" fn(*mut libc::ifaddrs)>> = OnceCell::new();
+
+    *INSTANCE.get_or_init(|| load_symbol("freeifaddrs"))
+}
+
+pub unsafe fn getifaddrs(ifap: *mut *mut libc::ifaddrs) -> libc::c_int {
+    // Android is complicated
+
+    // API 24+ contains the getifaddrs and freeifaddrs functions but the NDK doesn't
+    // expose those functions in ifaddrs.h when the minimum supported SDK is lower than 24
+    // and therefore we need to load them manually.
+    if let Some(dyn_getifaddrs) = get_getifaddrs() {
+        return dyn_getifaddrs(ifap);
+    }
+
+    // If API < 24 (or we can't load libc for some other reason), we fallback to using netlink
+    netlink_getifaddrs(ifap)
+}
+
+pub unsafe fn freeifaddrs(ifa: *mut libc::ifaddrs) {
+    if let Some(dyn_freeifaddrs) = get_freeifaddrs() {
+        return dyn_freeifaddrs(ifa);
+    }
+
+    netlink_freeifaddrs(ifa)
+}
+
+unsafe fn netlink_getifaddrs(ifap: *mut *mut libc::ifaddrs) -> libc::c_int {
+    todo!()
+}
+
+unsafe fn netlink_freeifaddrs(ifa: *mut libc::ifaddrs) {
+    todo!()
+}

src/interface/linux.rs

@@ -1,6 +1,6 @@
+use crate::interface::InterfaceType;
 use std::convert::TryFrom;
 use std::fs::read_to_string;
-use crate::interface::InterfaceType;
 
 pub fn get_interface_type(if_name: String) -> InterfaceType {
     let if_type_path: String = format!("/sys/class/net/{}/type", if_name);
@@ -11,12 +11,12 @@ pub fn get_interface_type(if_name: String) -> InterfaceType {
             match if_type_string.parse::<u32>() {
                 Ok(if_type) => {
                     return InterfaceType::try_from(if_type).unwrap_or(InterfaceType::Unknown);
-                },
+                }
                 Err(_) => {
                     return InterfaceType::Unknown;
                 }
             }
-        },
+        }
         Err(_) => {
             return InterfaceType::Unknown;
         }
@@ -33,12 +33,12 @@ pub fn get_interface_speed(if_name: String) -> Option<u64> {
                 Ok(if_speed) => {
                     // Convert Mbps to bps
                     return Some(if_speed * 1000000);
-                },
+                }
                 Err(_) => {
                     return None;
                 }
             }
-        },
+        }
         Err(_) => {
             return None;
         }

src/interface/mod.rs

@@ -4,9 +4,25 @@ pub use self::shared::*;
 mod types;
 pub use self::types::*;
 
-#[cfg(any(target_os = "linux", target_os = "macos", target_os = "openbsd", target_os = "freebsd", target_os = "netbsd", target_os = "ios", target_os = "android"))]
+#[cfg(any(
+    target_os = "linux",
+    target_os = "macos",
+    target_os = "openbsd",
+    target_os = "freebsd",
+    target_os = "netbsd",
+    target_os = "ios",
+    target_os = "android"
+))]
 mod unix;
-#[cfg(any(target_os = "linux", target_os = "macos", target_os = "openbsd", target_os = "freebsd", target_os = "netbsd", target_os = "ios", target_os = "android"))]
+#[cfg(any(
+    target_os = "linux",
+    target_os = "macos",
+    target_os = "openbsd",
+    target_os = "freebsd",
+    target_os = "netbsd",
+    target_os = "ios",
+    target_os = "android"
+))]
 use self::unix::*;
 
 #[cfg(target_os = "windows")]
@@ -17,12 +33,15 @@ use self::windows::*;
 #[cfg(any(target_os = "linux", target_os = "android"))]
 mod linux;
 
+#[cfg(target_os = "android")]
+mod android;
+
 #[cfg(any(target_os = "macos", target_os = "ios"))]
 mod macos;
 
-use std::net::IpAddr;
+use crate::gateway::Gateway;
 use crate::ip::{Ipv4Net, Ipv6Net};
-use crate::gateway::{Gateway};
+use std::net::IpAddr;
 
 /// Structure of MAC address
 #[derive(Clone, Debug)]
@@ -31,7 +50,9 @@ pub struct MacAddr(u8, u8, u8, u8, u8, u8);
 impl MacAddr {
     /// Construct a new MacAddr instance from the given octets
     pub fn new(octets: [u8; 6]) -> MacAddr {
-        MacAddr(octets[0], octets[1], octets[2], octets[3], octets[4], octets[5])
+        MacAddr(
+            octets[0], octets[1], octets[2], octets[3], octets[4], octets[5],
+        )
     }
     /// Returns an array of MAC address octets
     pub fn octets(&self) -> [u8; 6] {
@@ -39,7 +60,10 @@ impl MacAddr {
     }
     /// Return a formatted string of MAC address
     pub fn address(&self) -> String {
-        format!("{:02x}:{:02x}:{:02x}:{:02x}:{:02x}:{:02x}", self.0,self.1,self.2,self.3,self.4,self.5)
+        format!(
+            "{:02x}:{:02x}:{:02x}:{:02x}:{:02x}:{:02x}",
+            self.0, self.1, self.2, self.3, self.4, self.5
+        )
     }
     /// Construct an all-zero MacAddr instance
     pub fn zero() -> MacAddr {
@@ -48,7 +72,7 @@ impl MacAddr {
     /// Construct a new MacAddr instance from a colon-separated string of hex format
     pub fn from_hex_format(hex_mac_addr: &str) -> MacAddr {
         if hex_mac_addr.len() != 17 {
-            return MacAddr(0,0,0,0,0,0)
+            return MacAddr(0, 0, 0, 0, 0, 0);
         }
         let fields: Vec<&str> = hex_mac_addr.split(":").collect();
         let o1: u8 = u8::from_str_radix(&fields[0], 0x10).unwrap_or(0);
@@ -63,7 +87,11 @@ impl MacAddr {
 
 impl std::fmt::Display for MacAddr {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        let _ = write!(f,"{:<02x}:{:<02x}:{:<02x}:{:<02x}:{:<02x}:{:<02x}",self.0,self.1,self.2,self.3,self.4,self.5);
+        let _ = write!(
+            f,
+            "{:<02x}:{:<02x}:{:<02x}:{:<02x}:{:<02x}:{:<02x}",
+            self.0, self.1, self.2, self.3, self.4, self.5
+        );
         Ok(())
     }
 }
@@ -110,12 +138,12 @@ pub fn get_default_interface() -> Result<Interface, String> {
                 if iface.ipv4.iter().any(|x| x.addr == local_ipv4) {
                     return Ok(iface);
                 }
-            },
+            }
             IpAddr::V6(local_ipv6) => {
                 if iface.ipv6.iter().any(|x| x.addr == local_ipv6) {
                     return Ok(iface);
                 }
-            },
+            }
         }
     }
     Err(String::from("Default Interface not found"))
@@ -134,12 +162,12 @@ pub fn get_default_interface_index() -> Option<u32> {
                 if iface.ipv4.iter().any(|x| x.addr == local_ipv4) {
                     return Some(iface.index);
                 }
-            },
+            }
             IpAddr::V6(local_ipv6) => {
                 if iface.ipv6.iter().any(|x| x.addr == local_ipv6) {
                     return Some(iface.index);
                 }
-            },
+            }
         }
     }
     None
@@ -158,12 +186,12 @@ pub fn get_default_interface_name() -> Option<String> {
                 if iface.ipv4.iter().any(|x| x.addr == local_ipv4) {
                     return Some(iface.name);
                 }
-            },
+            }
             IpAddr::V6(local_ipv6) => {
                 if iface.ipv6.iter().any(|x| x.addr == local_ipv6) {
                     return Some(iface.name);
                 }
-            },
+            }
         }
     }
     None

src/interface/unix.rs

@@ -1,16 +1,19 @@
 use super::Interface;
 use super::MacAddr;
-use crate::sys;
 use crate::gateway;
 use crate::ip::{Ipv4Net, Ipv6Net};
+use crate::sys;
 
+use crate::interface::InterfaceType;
 use libc;
 use std::ffi::{CStr, CString};
 use std::mem::{self, MaybeUninit};
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
 use std::os::raw::c_char;
 use std::str::from_utf8_unchecked;
-use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
+
-use crate::interface::InterfaceType;
+#[cfg(target_os = "android")]
+use super::android::{freeifaddrs, getifaddrs};
 
 #[cfg(any(target_os = "openbsd", target_os = "freebsd", target_os = "netbsd"))]
 pub fn interfaces() -> Vec<Interface> {
@@ -26,21 +29,21 @@ pub fn interfaces() -> Vec<Interface> {
                     match gateway::unix::get_default_gateway(iface.name.clone()) {
                         Ok(gateway) => {
                             iface.gateway = Some(gateway);
-                        },
+                        }
-                        Err(_) => {},
+                        Err(_) => {}
+                    }
                 }
             }
-            },
             IpAddr::V6(local_ipv6) => {
                 if iface.ipv6.iter().any(|x| x.addr == local_ipv6) {
                     match gateway::unix::get_default_gateway(iface.name.clone()) {
                         Ok(gateway) => {
                             iface.gateway = Some(gateway);
-                        },
+                        }
-                        Err(_) => {},
+                        Err(_) => {}
+                    }
                 }
             }
-            },
         }
     }
     interfaces
@@ -64,21 +67,21 @@ pub fn interfaces() -> Vec<Interface> {
                     match gateway::unix::get_default_gateway(iface.name.clone()) {
                         Ok(gateway) => {
                             iface.gateway = Some(gateway);
-                        },
+                        }
-                        Err(_) => {},
+                        Err(_) => {}
+                    }
                 }
             }
-            },
             IpAddr::V6(local_ipv6) => {
                 if iface.ipv6.iter().any(|x| x.addr == local_ipv6) {
                     match gateway::unix::get_default_gateway(iface.name.clone()) {
                         Ok(gateway) => {
                             iface.gateway = Some(gateway);
-                        },
+                        }
-                        Err(_) => {},
+                        Err(_) => {}
+                    }
                 }
             }
-            },
         }
     }
     interfaces
@@ -104,21 +107,21 @@ pub fn interfaces() -> Vec<Interface> {
                     match gateway::linux::get_default_gateway(iface.name.clone()) {
                         Ok(gateway) => {
                             iface.gateway = Some(gateway);
-                        },
+                        }
-                        Err(_) => {},
+                        Err(_) => {}
+                    }
                 }
             }
-            },
             IpAddr::V6(local_ipv6) => {
                 if iface.ipv6.iter().any(|x| x.addr == local_ipv6) {
                     match gateway::linux::get_default_gateway(iface.name.clone()) {
                         Ok(gateway) => {
                             iface.gateway = Some(gateway);
-                        },
+                        }
-                        Err(_) => {},
+                        Err(_) => {}
+                    }
                 }
             }
-            },
         }
     }
     interfaces
@@ -144,10 +147,8 @@ fn sockaddr_to_network_addr(sa: *const libc::sockaddr) -> (Option<MacAddr>, Opti
 
             (Some(mac), None)
         } else {
-            let addr = sys::sockaddr_to_addr(
+            let addr =
-                mem::transmute(sa),
+                sys::sockaddr_to_addr(mem::transmute(sa), mem::size_of::<libc::sockaddr_storage>());
-                mem::size_of::<libc::sockaddr_storage>(),
-            );
 
             match addr {
                 Ok(SocketAddr::V4(sa)) => (None, Some(IpAddr::V4(*sa.ip()))),
@@ -158,7 +159,13 @@ fn sockaddr_to_network_addr(sa: *const libc::sockaddr) -> (Option<MacAddr>, Opti
     }
 }
 
-#[cfg(any(target_os = "openbsd", target_os = "freebsd", target_os = "netbsd", target_os = "macos", target_os = "ios"))]
+#[cfg(any(
+    target_os = "openbsd",
+    target_os = "freebsd",
+    target_os = "netbsd",
+    target_os = "macos",
+    target_os = "ios"
+))]
 fn sockaddr_to_network_addr(sa: *const libc::sockaddr) -> (Option<MacAddr>, Option<IpAddr>) {
     use crate::bpf;
     use std::net::SocketAddr;
@@ -180,10 +187,8 @@ fn sockaddr_to_network_addr(sa: *const libc::sockaddr) -> (Option<MacAddr>, Opti
 
             (Some(mac), None)
         } else {
-            let addr = sys::sockaddr_to_addr(
+            let addr =
-                mem::transmute(sa),
+                sys::sockaddr_to_addr(mem::transmute(sa), mem::size_of::<libc::sockaddr_storage>());
-                mem::size_of::<libc::sockaddr_storage>(),
-            );
 
             match addr {
                 Ok(SocketAddr::V4(sa)) => (None, Some(IpAddr::V4(*sa.ip()))),
@@ -197,7 +202,7 @@ fn sockaddr_to_network_addr(sa: *const libc::sockaddr) -> (Option<MacAddr>, Opti
 pub fn unix_interfaces() -> Vec<Interface> {
     let mut ifaces: Vec<Interface> = vec![];
     let mut addrs: MaybeUninit<*mut libc::ifaddrs> = MaybeUninit::uninit();
-    if unsafe { libc::getifaddrs(addrs.as_mut_ptr()) } != 0 {
+    if unsafe { getifaddrs(addrs.as_mut_ptr()) } != 0 {
         return ifaces;
     }
     let addrs = unsafe { addrs.assume_init() };
@@ -215,30 +220,26 @@ pub fn unix_interfaces() -> Vec<Interface> {
             match ip {
                 IpAddr::V4(ipv4) => {
                     let netmask: Ipv4Addr = match netmask {
-                        Some(netmask) => {
+                        Some(netmask) => match netmask {
-                            match netmask {
                             IpAddr::V4(netmask) => netmask,
                             IpAddr::V6(_) => Ipv4Addr::UNSPECIFIED,
-                            }
                         },
                         None => Ipv4Addr::UNSPECIFIED,
                     };
                     let ipv4_net: Ipv4Net = Ipv4Net::new_with_netmask(ipv4, netmask);
                     ini_ipv4.push(ipv4_net);
-                },
+                }
                 IpAddr::V6(ipv6) => {
                     let netmask: Ipv6Addr = match netmask {
-                        Some(netmask) => {
+                        Some(netmask) => match netmask {
-                            match netmask {
                             IpAddr::V4(_) => Ipv6Addr::UNSPECIFIED,
                             IpAddr::V6(netmask) => netmask,
-                            }
                         },
                         None => Ipv6Addr::UNSPECIFIED,
                     };
                     let ipv6_net: Ipv6Net = Ipv6Net::new_with_netmask(ipv6, netmask);
                     ini_ipv6.push(ipv6_net);
-                },
+                }
             }
         }
         let interface: Interface = Interface {
@@ -265,30 +266,26 @@ pub fn unix_interfaces() -> Vec<Interface> {
                     match ip {
                         IpAddr::V4(ipv4) => {
                             let netmask: Ipv4Addr = match netmask {
-                                Some(netmask) => {
+                                Some(netmask) => match netmask {
-                                    match netmask {
                                     IpAddr::V4(netmask) => netmask,
                                     IpAddr::V6(_) => Ipv4Addr::UNSPECIFIED,
-                                    }
                                 },
                                 None => Ipv4Addr::UNSPECIFIED,
                             };
                             let ipv4_net: Ipv4Net = Ipv4Net::new_with_netmask(ipv4, netmask);
                             iface.ipv4.push(ipv4_net);
-                        },
+                        }
                         IpAddr::V6(ipv6) => {
                             let netmask: Ipv6Addr = match netmask {
-                                Some(netmask) => {
+                                Some(netmask) => match netmask {
-                                    match netmask {
                                     IpAddr::V4(_) => Ipv6Addr::UNSPECIFIED,
                                     IpAddr::V6(netmask) => netmask,
-                                    }
                                 },
                                 None => Ipv6Addr::UNSPECIFIED,
                             };
                             let ipv6_net: Ipv6Net = Ipv6Net::new_with_netmask(ipv6, netmask);
                             iface.ipv6.push(ipv6_net);
-                        },
+                        }
                     }
                 }
                 found = true;
@@ -299,14 +296,29 @@ pub fn unix_interfaces() -> Vec<Interface> {
         }
         addr = addr_ref.ifa_next;
     }
-    unsafe{ libc::freeifaddrs(addrs); } 
+    unsafe {
+        freeifaddrs(addrs);
+    }
     for iface in &mut ifaces {
         let name = CString::new(iface.name.as_bytes()).unwrap();
-        unsafe { iface.index = libc::if_nametoindex(name.as_ptr()); }
+        unsafe {
+            iface.index = libc::if_nametoindex(name.as_ptr());
+        }
     }
     ifaces
 }
 
+#[cfg(not(target_os = "android"))]
+unsafe fn getifaddrs(ifap: *mut *mut libc::ifaddrs) -> libc::c_int {
+    // Not android, everything is easy
+    libc::getifaddrs(ifap)
+}
+
+#[cfg(not(target_os = "android"))]
+unsafe fn freeifaddrs(ifa: *mut libc::ifaddrs) {
+    libc::freeifaddrs(ifa);
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;