From c3618488f2730eae9634987b0969a497442aa0df Mon Sep 17 00:00:00 2001
From: Jordan Bancino <jordan@bancino.net>
Date: Thu, 15 Dec 2022 20:18:12 +0000
Subject: [PATCH] Hexdump leaked memory to the log for debugging.

---
 TODO.txt                         |  3 ++
 man/man7/telodendria-changelog.7 | 16 +++++--
 src/Telodendria.c                | 72 ++++++++++++++++++++++++++++++++
 3 files changed, 88 insertions(+), 3 deletions(-)

diff --git a/TODO.txt b/TODO.txt
index 7aa951c..dc35c33 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -13,6 +13,9 @@ Milestone: v0.1.1
 
 [x] DbDelete()
 [x] UtilRandomString()
+[x] Hex dump leaked memory
+[ ] Leaks in DB
+
 [ ] Database version file
 [ ] User registration
 
diff --git a/man/man7/telodendria-changelog.7 b/man/man7/telodendria-changelog.7
index 62505e9..48504a6 100644
--- a/man/man7/telodendria-changelog.7
+++ b/man/man7/telodendria-changelog.7
@@ -49,6 +49,16 @@ be used extensively for generating session tokens, device
 IDs, access tokens, and more. This generator is seeded by
 the current timestamp and the thread ID, so it should be
 fairly random.
+.It
+Leaked memory is now hexdump-ed out to the log if the log
+level is set to debug. This greatly simplifies debugging,
+because developers can now easily see exactly what the
+contents of the leaked memory are. Note that in some
+circumstances, this memory may contain sensitive data,
+such as access tokens, usernames, or passwords. However,
+.Nm
+should not be leaking memory at all, so if you encounter
+any leaks, please report them.
 .El
 .Pp
 Bug fixes:
@@ -70,11 +80,11 @@ Fixed an "off-by-one" error in the HTTP server request
 parser that prevented GET parameters from being parsed.
 .It
 Fixed the database file name generator to prevent directory
-traversal attacks by replacing characters with special meaning
-with safer characters.
+traversal attacks by replacing special characters with
+safer ones.
 .El
 .Pp
-Misc.:
+Misc:
 .Bl -bullet
 .It
 Fixed a bug in
diff --git a/src/Telodendria.c b/src/Telodendria.c
index b036583..a8ade89 100644
--- a/src/Telodendria.c
+++ b/src/Telodendria.c
@@ -24,6 +24,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <ctype.h>
 #include <unistd.h>
 #include <errno.h>
 #include <signal.h>
@@ -79,9 +80,80 @@ TelodendriaMemoryIterator(MemoryInfo * i, void *args)
     /* We haven't freed the logger memory yet */
     if (MemoryInfoGetPointer(i) != lc)
     {
+#define LEN 16
+        char hexBuf[(LEN * 2) + LEN + 1];
+        char asciiBuf[LEN + 1];
+        const unsigned char *pc = MemoryInfoGetPointer(i);
+        size_t pI = 0;
+        size_t hI = 0;
+        size_t aI = 0;
+
         Log(lc, LOG_WARNING, "%s:%d: %lu bytes of memory at %p leaked.",
             MemoryInfoGetFile(i), MemoryInfoGetLine(i),
             MemoryInfoGetSize(i), MemoryInfoGetPointer(i));
+
+        for (pI = 0; pI < MemoryInfoGetSize(i); pI++)
+        {
+            if (pI > 0 && pI % LEN == 0)
+            {
+                hexBuf[hI - 1] = '\0';
+                asciiBuf[aI] = '\0';
+
+                Log(lc, LOG_DEBUG, "%04x: %s | %s |",
+                    pI - LEN, hexBuf, asciiBuf);
+
+                sprintf(hexBuf, "%02x ", pc[pI]);
+                hI = 3;
+
+                if (isprint(pc[pI]))
+                {
+                    asciiBuf[0] = pc[pI];
+                }
+                else
+                {
+                    asciiBuf[0] = '.';
+                }
+                asciiBuf[1] = '\0';
+                aI = 1;
+            }
+            else
+            {
+                if (isprint(pc[pI]))
+                {
+                    asciiBuf[aI] = pc[pI];
+                }
+                else
+                {
+                    asciiBuf[aI] = '.';
+                }
+                aI++;
+
+                sprintf(hexBuf + hI, "%02x ", pc[pI]);
+                hI += 3;
+            }
+        }
+
+        while (hI < sizeof(hexBuf) - 2)
+        {
+            hexBuf[hI] = ' ';
+            hI++;
+        }
+
+        while (aI < sizeof(asciiBuf) - 1)
+        {
+            asciiBuf[aI] = ' ';
+            aI++;
+        }
+
+        hexBuf[hI] = '\0';
+        asciiBuf[aI] = '\0';
+
+        Log(lc, LOG_DEBUG, "%04x: %s | %s |",
+            pI - (pI % LEN), hexBuf, asciiBuf);
+
+        Log(lc, LOG_DEBUG, "%04x", pI);
+
+#undef LEN
     }
 }