From c4920a60c6af935cc347fe3436dd7ff62a9e380d Mon Sep 17 00:00:00 2001
From: junglefowl <junglefowl@riseup.net>
Date: Tue, 24 Jan 2017 18:40:01 +0000
Subject: [PATCH 1/2] Do not truncate too long hostnames

If a hostname is supplied to tor-resolve which is too long, it will be
silently truncated, resulting in a different hostname lookup:

$ tor-resolve $(python -c 'print("google.com" + "m" * 256)')

If tor-resolve uses SOCKS5, the length is stored in an unsigned char,
which overflows in this case and leads to the hostname "google.com".
As this one is a valid hostname, it returns an address instead of giving
an error due to the invalid supplied hostname.
---
 src/tools/tor-resolve.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/tools/tor-resolve.c b/src/tools/tor-resolve.c
index 29f85c4d1..6ac866d3c 100644
--- a/src/tools/tor-resolve.c
+++ b/src/tools/tor-resolve.c
@@ -80,6 +80,10 @@ build_socks_resolve_request(char **out,
     }
     ipv6 = reverse && tor_addr_family(&addr) == AF_INET6;
     addrlen = reverse ? (ipv6 ? 16 : 4) : 1 + strlen(hostname);
+    if (addrlen > UINT8_MAX) {
+      log_err(LD_GENERAL, "Hostname is too long!");
+      return -1;
+    }
     len = 6 + addrlen;
     *out = tor_malloc(len);
     (*out)[0] = 5; /* SOCKS version 5 */

From a271ad2a7efed53c42bc84b0f781a6603bd494fc Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Wed, 25 Jan 2017 13:15:37 -0500
Subject: [PATCH 2/2] changes file for 21280

---
 changes/bug21280 | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 changes/bug21280

diff --git a/changes/bug21280 b/changes/bug21280
new file mode 100644
index 000000000..e9f0bc174
--- /dev/null
+++ b/changes/bug21280
@@ -0,0 +1,5 @@
+  o Minor bugfixes (tor-resolve):
+    - The tor-resolve command line tool now rejects hostnames over 255
+      characters in length. Previously, it would silently truncate
+      them, which could lead to bugs. Fixes bug 21280; bugfix on 0.0.9pre5.
+      Patch by "junglefowl".