From b9a8951cf86214a3dcb430ae0d34e8d5dc1adb11 Mon Sep 17 00:00:00 2001
From: Luke Bratch <luke@bratch.co.uk>
Date: Wed, 10 Jul 2019 20:44:35 +0100
Subject: Ensure log filenames are safe for writing.

---
 functions.c |  9 +++++++++
 functions.h |  3 +++
 logging.c   | 31 +++++++++++++++++++++++++++----
 3 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/functions.c b/functions.c
index 8bbc213..938b8b1 100644
--- a/functions.c
+++ b/functions.c
@@ -1253,3 +1253,12 @@ int getclientcodetime(char *code, struct clientcodes *clientcodes) {
   // If we got here, the code was never found
   return 0;
 }
+
+// Replace any instances of "find" with "replace" in the string "str"
+void replacechar(char *str, char find, char replace) {
+  for (size_t i = 0; i < strlen(str); i++) {
+    if (str[i] == find) {
+      str[i] = replace;
+    }
+  }
+}
diff --git a/functions.h b/functions.h
index 29ebff5..009a019 100644
--- a/functions.h
+++ b/functions.h
@@ -178,4 +178,7 @@ int setclientcodetime(char *code, struct clientcodes *clientcodes);
 // Return the timestamp that a given client last disconnected, or 0 on failure.
 int getclientcodetime(char *code, struct clientcodes *clientcodes);
 
+// Replace any instances of "find" with "replace" in the string "str"
+void replacechar(char *str, char find, char replace);
+
 #endif
diff --git a/logging.c b/logging.c
index 5b790b1..6e8d9b7 100644
--- a/logging.c
+++ b/logging.c
@@ -77,10 +77,24 @@ int logline(char *str, char *ournick, char *basedir, int type) {
     debugprint(DEBUG_FULL, "logline(): extracted '%s'.\n", tokens[i]);
   }
 
+  // Make "filename safe" copies of from and to names to ensure filename ends up being safe
+  char from[MAXCHAR], to[MAXCHAR];
+  strcpy(from, tokens[0]);
+  strcpy(to, tokens[2]);
+  // Remove unsafe characters (assuming POSIX, just strip "/" and replace with "_")
+  replacechar(from, '/', '_');
+  replacechar(to, '/', '_');
+  // Ensure filename wouldn't be too long
+  if (strlen(from) > NAME_MAX || strlen(to) > NAME_MAX) {
+    debugprint(DEBUG_CRIT, "Filename would be too long if logging either '%s' or '%s', returning!\n", from, to);
+    return 0;
+  }
+
   switch(type) {
     case LOG_PRIVMSG:
       // Extract the username from the prefix
       extractnickfromprefix(tokens[0]);
+      extractnickfromprefix(from);
 
       // Remove the leading ":" from the real message
       stripprefix(str);
@@ -88,10 +102,16 @@ int logline(char *str, char *ournick, char *basedir, int type) {
       // Build the log filename
       // If the message was sent to us, then log it in the sender's log file
       if (strncmp(tokens[2], ournick, strlen(tokens[0])) == 0) {
-        snprintf(filename, MAXCHAR, "%s/logs/%s.log", basedir, tokens[0]);
+        if (!snprintf(filename, MAXCHAR, "%s/logs/%s.log", basedir, from)) {
+          debugprint(DEBUG_CRIT, "Error while log filename for from name, returning!\n");
+          return 0;
+        }
       } else {
         // Otherwise log it in the "to" log file
-        snprintf(filename, MAXCHAR, "%s/logs/%s.log", basedir, tokens[2]);
+        if (!snprintf(filename, MAXCHAR, "%s/logs/%s.log", basedir, to)) {
+          debugprint(DEBUG_CRIT, "Error while log filename for to name, returning!\n");
+          return 0;
+        }
       }
 
       debugprint(DEBUG_FULL, "logline(): Logging PRIVMSG from '%s' to '%s' message '%s' in filename '%s'.\n", tokens[0], tokens[2], str, filename);
@@ -112,7 +132,7 @@ int logline(char *str, char *ournick, char *basedir, int type) {
         return 0;
       }
 
-      snprintf(filename, MAXCHAR, "%s/logs/%s.log", basedir, tokens[2] + pos);
+      snprintf(filename, MAXCHAR, "%s/logs/%s.log", basedir, to + pos);
 
       debugprint(DEBUG_FULL, "logline(): Logging JOIN/PART to/from '%s' in filename '%s'.\n", tokens[2] + pos, filename);
 
@@ -151,7 +171,10 @@ int logline(char *str, char *ournick, char *basedir, int type) {
       // Remove the leading ":" from the topic
       stripprefix(str);
 
-      snprintf(filename, MAXCHAR, "%s/logs/%s.log", basedir, tokens[2]);
+      if (!snprintf(filename, MAXCHAR, "%s/logs/%s.log", basedir, to)) {
+        debugprint(DEBUG_CRIT, "Error while log filename for topic, returning!\n");
+        return 0;
+      }
 
       debugprint(DEBUG_FULL, "logline(): Logging TOPIC for '%s' in filename '%s'.\n", tokens[2], filename);
 
-- 
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