Bug 18800: Remove localhost DNS lookup in nsProfileLock.cpp

Instead of using the local computer's IP address within symlink-based profile lock signatures, always use 127.0.0.1.

Bug 18800: Remove localhost DNS lookup in nsProfileLock.cpp
6e17cef8 · Kathleen Brade · Georg Koppen · 04be6d9e · 6e17cef8
Commit 6e17cef8 authored Apr 21, 2016 by Kathleen Brade Committed by Georg Koppen Mar 3, 2017
--- a/toolkit/profile/nsProfileLock.cpp
+++ b/toolkit/profile/nsProfileLock.cpp
@@ -344,20 +344,16 @@ nsresult nsProfileLock::LockWithSymlink(nsIFile *aLockFile, bool aHaveFcntlLock)
    if (!mReplacedLockTime)
        aLockFile->GetLastModifiedTimeOfLink(&mReplacedLockTime);

+    // For Tor Browser, avoid a DNS lookup here so the Tor network is not
+    // bypassed. Instead, always use 127.0.0.1 for the IP address portion
+    // of the lock signature, which may cause the browser to refuse to
+    // start in the rare event that all of the following conditions are met:
+    //   1. The browser profile is on a network file system.
+    //   2. The file system does not support fcntl() locking.
+    //   3. Tor Browser is run from two different computers at the same time.
    struct in_addr inaddr;
    inaddr.s_addr = htonl(INADDR_LOOPBACK);

-    char hostname[256];
-    PRStatus status = PR_GetSystemInfo(PR_SI_HOSTNAME, hostname, sizeof hostname);
-    if (status == PR_SUCCESS)
-    {
-        char netdbbuf[PR_NETDB_BUF_SIZE];
-        PRHostEnt hostent;
-        status = PR_GetHostByName(hostname, netdbbuf, sizeof netdbbuf, &hostent);
-        if (status == PR_SUCCESS)
-            memcpy(&inaddr, hostent.h_addr, sizeof inaddr);
-    }
-
    char *signature =
        PR_smprintf("%s:%s%lu", inet_ntoa(inaddr), aHaveFcntlLock ? "+" : "",
                    (unsigned long)getpid());