From 13a0b901492901638a7abc90bb2935a9c0387f75 Mon Sep 17 00:00:00 2001
From: Charles Kerr <charles.kerr@canonical.com>
Date: Wed, 9 Mar 2016 17:19:23 -0600
Subject: add human-readable fingerprint extraction from the adb public keys

---
 src/adbd-client.cpp | 39 +++++++++++++++++++++++++++++++++++++++
 src/adbd-client.h   |  1 +
 src/main.cpp        |  2 +-
 src/usb-snap.cpp    |  4 ++--
 4 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/src/adbd-client.cpp b/src/adbd-client.cpp
index 38f202f..edd403c 100644
--- a/src/adbd-client.cpp
+++ b/src/adbd-client.cpp
@@ -22,6 +22,9 @@
 #include <gio/gio.h>
 #include <gio/gunixsocketaddress.h>
 
+#include <algorithm>
+#include <cctype>
+#include <cstring>
 #include <chrono>
 #include <condition_variable>
 #include <mutex>
@@ -89,6 +92,7 @@ private:
             auto self = data->self;
             struct PKRequest req;
             req.public_key = data->public_key;
+            req.fingerprint = get_fingerprint(req.public_key);
             req.respond = [self](PKResponse response){self->on_public_key_response(response);};
             self->m_on_pk_request(req);
         }
@@ -219,6 +223,37 @@ private:
         }
     }
 
+    static std::string get_fingerprint(const std::string& public_key)
+    {
+        // The first token is base64-encoded data, so cut on the first whitespace
+        const std::string base64 (
+            public_key.begin(),
+            std::find_if(
+                public_key.begin(), public_key.end(),
+                [](const std::string::value_type& ch){return std::isspace(ch);}
+            )
+        );
+
+        gsize digest_len {};
+        auto digest = g_base64_decode(base64.c_str(), &digest_len);
+
+        auto checksum = g_compute_checksum_for_data(G_CHECKSUM_MD5, digest, digest_len);
+        const gsize checksum_len = checksum ? strlen(checksum) : 0;
+
+        // insert ':' between character pairs; eg "ff27b5f3" --> "ff:27:b5:f3"
+        std::string fingerprint;
+        for (gsize i=0; i<checksum_len; ) {
+            fingerprint.append(checksum+i, checksum+i+2);
+            if (i < checksum_len-2)
+                fingerprint.append(":");
+            i += 2;
+        }
+
+        g_clear_pointer(&digest, g_free);
+        g_clear_pointer(&checksum, g_free);
+        return fingerprint;
+    }
+
     const std::string m_socket_path;
     GCancellable* m_cancellable = nullptr;
     std::thread m_worker_thread;
@@ -241,6 +276,10 @@ AdbdClient::~AdbdClient()
 {
 }
 
+/***
+****
+***/
+
 GAdbdClient::GAdbdClient(const std::string& socket_path):
     impl{new Impl{socket_path}}
 {
diff --git a/src/adbd-client.h b/src/adbd-client.h
index aef7674..dcee2f1 100644
--- a/src/adbd-client.h
+++ b/src/adbd-client.h
@@ -44,6 +44,7 @@ public:
 
     struct PKRequest {
         std::string public_key;
+        std::string fingerprint;
         std::function<void(PKResponse)> respond;
     };
 
diff --git a/src/main.cpp b/src/main.cpp
index 62eca62..151b642 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -61,7 +61,7 @@ main(int /*argc*/, char** /*argv*/)
     static constexpr char const * ADB_SOCKET_PATH {"/dev/socket/adb"};
     GAdbdClient adbd_client{ADB_SOCKET_PATH};
     adbd_client.on_pk_request().connect([](const AdbdClient::PKRequest& req){
-        auto snap = new UsbSnap(req.public_key);
+        auto snap = new UsbSnap(req.fingerprint);
         snap->on_user_response().connect([req,snap](AdbdClient::PKResponse response, bool /*FIXME: remember_choice*/){
             req.respond(response);
             g_idle_add([](gpointer gsnap){delete static_cast<UsbSnap*>(gsnap); return G_SOURCE_REMOVE;}, snap); // delete-later
diff --git a/src/usb-snap.cpp b/src/usb-snap.cpp
index 40f02a2..87f4673 100644
--- a/src/usb-snap.cpp
+++ b/src/usb-snap.cpp
@@ -217,8 +217,8 @@ private:
         m_notification_id = 0;
     }
 
-    static constexpr char const * ACTION_ALLOW{"allow"};
-    static constexpr char const * ACTION_DENY{"deny"};
+    static constexpr char const * ACTION_ALLOW {"allow"};
+    static constexpr char const * ACTION_DENY  {"deny"};
 
     static constexpr char const * BUS_NAME    {"org.freedesktop.Notifications" };
     static constexpr char const * IFACE_NAME  {"org.freedesktop.Notifications" };
-- 
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