Bug 1554976 - Use mdns_service to generate UUIDs; r=mjf

With the move to the socket process, the UUID service is no longer available
in nricectx. This adds a pair of helper functions to mdns_service to generate
UUIDs and uses them to generate hostnames inside nricectx.

Differential Revision: https://phabricator.services.mozilla.com/D42150

--HG--
extra : moz-landing-system : lando

Cargo.lock

@@ -1754,6 +1754,7 @@ dependencies = [
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "mio 0.6.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "socket2 0.3.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "uuid 0.7.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]

media/mtransport/mdns_service/Cargo.toml

@@ -10,3 +10,4 @@ dns-parser = "0.8.0"
 log = "0.4"
 mio = "0.6"
 socket2 = { version = "0.3.9", features = ["reuseport"] }
+uuid = { version = "0.7", features = ["v4"] }

media/mtransport/mdns_service/mdns_service.h

@@ -16,4 +16,8 @@ void mdns_service_stop(MDNSService* serv);
 
 void mdns_service_unregister_hostname(MDNSService* serv, const char* hostname);
 
+const char* mdns_service_generate_uuid();
+
+void mdns_service_free_uuid(const char* uuid);
+
 }  // extern "C"

media/mtransport/mdns_service/src/lib.rs

@@ -7,12 +7,14 @@ use get_if_addrs;
 use socket2::{Domain, Socket, Type};
 use std::collections::HashMap;
 use std::ffi::CStr;
+use std::ffi::CString;
 use std::io;
 use std::net;
 use std::os::raw::c_char;
 use std::sync::mpsc::channel;
 use std::thread;
 use std::time;
+use uuid::Uuid;
 
 #[macro_use]
 extern crate log;
@@ -301,3 +303,21 @@ pub extern "C" fn mdns_service_unregister_hostname(
         (*serv).unregister_hostname(&hostname);
     }
 }
+
+#[no_mangle]
+pub extern "C" fn mdns_service_generate_uuid() -> *const c_char {
+    let uuid = Uuid::new_v4().to_hyphenated().to_string();
+    match CString::new(uuid) {
+        Ok(uuid) => {
+            uuid.into_raw()
+        }
+        Err(_) => unreachable!()  // UUID should not contain 0 byte
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn mdns_service_free_uuid(uuid: *mut c_char) {
+    unsafe {
+        CString::from_raw(uuid);
+    }
+}

media/mtransport/nricectx.cpp

@@ -97,6 +97,10 @@ extern "C" {
 #include "rlogconnector.h"
 #include "test_nr_socket.h"
 
+extern "C" {
+#include "mdns_service/mdns_service.h"
+}
+
 namespace mozilla {
 
 using std::shared_ptr;
@@ -1060,28 +1064,11 @@ void NrIceCtx::GenerateObfuscatedAddress(nr_ice_candidate* candidate,
     if (iter != obfuscated_host_addresses_.end()) {
       *mdns_address = iter->second;
     } else {
-      nsresult rv;
-      nsCOMPtr<nsIUUIDGenerator> uuidgen =
-          do_GetService("@mozilla.org/uuid-generator;1", &rv);
-
-      if (NS_FAILED(rv)) {
-        return;
-      }
-
-      nsID id;
-      rv = uuidgen->GenerateUUIDInPlace(&id);
-
-      if (NS_FAILED(rv)) {
-        return;
-      }
-
-      char chars[NSID_LENGTH];
-      id.ToProvidedString(chars);
-
+      const char* uuid = mdns_service_generate_uuid();
       std::ostringstream o;
-      chars[NSID_LENGTH - 2] = 0;  // trim trailing } from uuid
-      o << &chars[1] << ".local";  // trim leading { from uuid
+      o << uuid << ".local";
       *mdns_address = o.str();
+      mdns_service_free_uuid(uuid);
 
       obfuscated_host_addresses_[*actual_address] = *mdns_address;
     }