Implement update checking using the command "BLABOUNCER UPDATECHECK", or optionally (enabled by default, toggled with configuration option "checkupdates") at startup and successful client authentication.HEADmaster

This is implemented using a DNS TXT record check to the domain "version.blabouncer.blatech.net".

9 files changed, 212 insertions, 3 deletions

diff --git a/Makefile b/Makefile
index baa334c..7b02278 100644
--- a/Makefile
+++ b/Makefile
@@ -7,7 +7,7 @@ ifeq ($(PREFIX),)
 endif
 
 blabouncer: blabouncer.c functions.c sockets.c config.c replay.c logging.c message.c config.h functions.h logging.h message.h replay.h sockets.h structures.h
-	$(CC) -D_DEFAULT_SOURCE -D_BSD_SOURCE -DVERSION=\"$(GIT_VERSION)\" -std=gnu99 -Wall -Wextra -lssl -lcrypto -o $(BINARY) blabouncer.c functions.c sockets.c config.c replay.c logging.c message.c
+	$(CC) -D_DEFAULT_SOURCE -D_BSD_SOURCE -DVERSION=\"$(GIT_VERSION)\" -std=gnu99 -Wall -Wextra -lssl -lcrypto -lresolv -o $(BINARY) blabouncer.c functions.c sockets.c config.c replay.c logging.c message.c
 
 .PHONY: clean
 clean:
diff --git a/README b/README
index e3e5c7b..d03330d 100644
--- a/README
+++ b/README
@@ -56,6 +56,7 @@ what this client has missed.)
 "BLABOUNCER DISCONNECT [FD]" (To disconnect a client with file descriptor number [FD] (see LISTCLIENTS
 output).)
 "BLABOUNCER VERSION" (To show the current blabouncer version.)
+"BLABOUNCER UPDATECHECK" (To check for blabouncer updates.  Set checkupdates = "0" to stop this happening automatically.)
 
 Blabouncer commands are all prefixed with BLABOUNCER which you can usually send using "/QUOTE BLABOUNCER".
 
diff --git a/TODO b/TODO
index 895e3c2..eb7bf2b 100644
--- a/TODO
+++ b/TODO
@@ -52,8 +52,6 @@ QUIT not logged in all channels a person was in?  (e.g. Joey Mon  1 Apr 20:49:14
 
 "/whois" with no nick - "No nickname given" goes to all clients - fixable?
 
-Ability to check for updates (and optional at startup?).
-
 Absurd CPU usage and duration doing "/BLABOUNCER REPLAY 24:0" approx. 14/09/2024 17:35.
 
 Custom OpenSSL protocols/ciphers?
diff --git a/blabouncer.c b/blabouncer.c
index b3e239d..443c75c 100644
--- a/blabouncer.c
+++ b/blabouncer.c
@@ -1331,6 +1331,13 @@ int main(int argc, char *argv[]) {
     strncat(conffailmsg, "Error getting 'alertautheddisconnect' from configuration file.\n", sizeof conffailmsg - strlen(conffailmsg) - 1);
   }
 
+  // Is check for updates upon startup and successful client authentication enabled?
+  settings.checkupdates = getconfint("checkupdates", settings.conffile);
+  if (errno == ECONFINT) {
+    conffail = 1;
+    strncat(conffailmsg, "Error getting 'checkupdates' from configuration file.\n", sizeof conffailmsg - strlen(conffailmsg) - 1);
+  }
+
   // How many debug logs should we keep?
   settings.debugkeep = getconfint("debugkeep", settings.conffile);
   if (errno == ECONFINT) {
@@ -1439,6 +1446,21 @@ int main(int argc, char *argv[]) {
 
   debugprint(DEBUG_SOME, "Using configuration file '%s'.\n", settings.conffile);
 
+  // Check for updates (if enabled in configuration file with checkupdates = "1")
+  if (settings.checkupdates) {
+    debugprint(DEBUG_SOME, "Checking for blabouncer updates (checkupdates = \"0\" to disable)...\n");
+    char version[MAXDNSTXTLEN];
+    version[0] = '\0';
+    int ret = checkversion(version);
+    if (ret == 1) {
+      debugprint(DEBUG_SOME, "main(): blabouncer appears to be up to date.\n");
+    } else if (ret == -1) {
+      debugprint(DEBUG_SOME, "main(): blabouncer appears to be out of date, latest version is %s.\n", version);
+    } else {
+      debugprint(DEBUG_CRIT, "main(): Version check failed!\n");
+    }
+  }
+
   // Unless specified otherwise on the command line, fork to background
   if (settings.background) {
     pid_t pid, sid;
diff --git a/blabouncer.conf.example b/blabouncer.conf.example
index 2281806..4e8e7f1 100644
--- a/blabouncer.conf.example
+++ b/blabouncer.conf.example
@@ -123,3 +123,7 @@ alertunautheddisconnect = "1"
 
 # Send NOTICE to all other clients upon authenticated client disconnections ("1" for yes or "0" for no)
 alertautheddisconnect = "1"
+
+# Check for updates upon startup and successful client authentication ("1" for yes or "0" for no)
+# This sends a DNS TXT request to blatech.net, disable this if you do not wish for that to happen
+checkupdates = "1"
diff --git a/functions.c b/functions.c
index 54e2663..35be8e4 100644
--- a/functions.c
+++ b/functions.c
@@ -1710,3 +1710,119 @@ void strlower(char *string) {
     string[i] = tolower(string[i]);
   }
 }
+
+// Gets a single TXT record from DNS for "dnsname" and stores the result in "record"
+// Returns 1 on success or 0 on failure
+// TODO: If this is ever used for more than just version checks, then it needs to do more than a single record.
+int gettxtrecordsingle(char *dnsname, char *record) {
+  debugprint(DEBUG_FULL, "gettxtrecordsingle(): given '%s'.\n", dnsname);
+
+  unsigned char buffer[8000] = {0};
+  char result[MAXDNSTXTLEN] = {0};
+  const unsigned char *presult = NULL;
+  struct __res_state resState = {0};
+  ns_msg nsMsg = {0};
+  ns_rr rr;
+
+  int type = 0;
+  int ret = 0;
+  int size = 0;
+  int count = 0;
+  long unsigned int len = 0;
+  int res_init = 0;
+
+  ret = res_ninit(&resState);
+
+  if (ret) {
+    debugprint(DEBUG_CRIT, "gettxtrecordsingle(): res_ninit() returned failure (it returned %d)!  Returning 0.\n", ret);
+    return 0;
+  } else {
+    res_init = 1;
+  }
+
+  memset(buffer, 0, sizeof (buffer));
+  size = res_nquery(&resState, dnsname, C_IN, T_TXT, buffer, sizeof(buffer) - 1);
+
+  if (size < 1) {
+    res_nclose(&resState);
+    debugprint(DEBUG_CRIT, "gettxtrecordsingle(): res_nquery() returned zero-length or failure (it returend %d)!  Returning 0.\n", size);
+    return 0;
+  }
+
+  ret = ns_initparse(buffer, size, &nsMsg);
+
+  if (ret) {
+    res_nclose(&resState);
+    debugprint(DEBUG_CRIT, "gettxtrecordsingle(): ns_initparse() returned failure (failed to parse the buffer buffer?) (it returned %d)!  Returning 0.\n", ret);
+    return 0;
+  }
+
+  count = ns_msg_count(nsMsg, ns_s_an);
+
+  for (int i = 0; i < count; i++) {
+    ret = ns_parserr(&nsMsg, ns_s_an, i , &rr);
+
+    if (ret) {
+      res_nclose(&resState);
+      return 0;
+    }
+
+    type = ns_rr_type(rr);
+    if (ns_t_txt == type) {
+      len = ns_rr_rdlen(rr);
+      presult = ns_rr_rdata(rr);
+
+      if ((len > 1) && (len < sizeof(result))) {
+        len--;
+        memcpy (result, presult+1, len);
+        result[len] = '\0';
+        debugprint(DEBUG_FULL, "gettxtrecordsingle(): record '%d' from DNS is '%s'.\n", i, result);
+
+        // Only using the first result
+        if (i == 0) {
+          strncpy(record, result, sizeof(result) - 1);
+        }
+      }
+   }
+  }
+
+  debugprint(DEBUG_FULL, "gettxtrecordsingle(): using record '%s'.\n", result);
+
+  if (res_init) {
+    res_nclose (&resState);
+  }
+
+  return 1;
+}
+
+// Gets the latest blabouncer version string from DNS and stores it in "version"
+// Ignores the Git version portion (everything after the first '-') of VERSION, if present
+// Returns 1 if local VERSION is current, -1 if local VERSION is not current, or 0 on failure
+int checkversion(char *version) {
+  if (!gettxtrecordsingle(VERSIONTXTNAME, version)) {
+    debugprint(DEBUG_CRIT, "checkversion(): gettxtrecordsingle() failure and the buffer contains '%s', returning 0.\n", version);
+    return 0;
+  } else {
+    debugprint(DEBUG_FULL, "checkversion(): gettxtrecordsingle() success and the returned record is '%s'.\n", version);
+  }
+
+  // Ignore the Git version portion (everything after the first '-') of VERSION, if present
+  char localversion[MAXDNSTXTLEN];
+  strncpy(localversion, VERSION, sizeof(localversion) - 1);
+
+  for (size_t i = 0; i < strlen(localversion); i++) {
+    if (localversion[i] == '-') {
+      localversion[i] = '\0';
+      debugprint(DEBUG_FULL, "checkversion(): Trimmed local VERSION string to '%s'.\n", localversion);
+      break;
+    }
+  }
+
+  if (strncmp(localversion, version, sizeof(localversion))) {
+    debugprint(DEBUG_SOME, "checkversion(): Returned version '%s' doesn't match expected '%s', returning -1.\n", version, localversion);
+    return -1;
+  } else {
+    debugprint(DEBUG_FULL, "checkversion(): Returned version '%s' matches expected '%s', returning 1.\n", version, localversion);
+    return 1;
+  }
+}
diff --git a/functions.h b/functions.h
index ff9d656..72a2129 100644
--- a/functions.h
+++ b/functions.h
@@ -28,6 +28,7 @@
 #include <netinet/in.h>
 #include <sys/socket.h>
 #include <arpa/inet.h>
+#include <resolv.h>
 #include <sys/select.h>
 #include <stdarg.h>
 #include <limits.h>
@@ -52,6 +53,8 @@
 #define MAXCLIENTS 32 // Maximum number of clients that can connect to the bouncer at a time
 #define MAXCHANNELS 1024 // Let's assume 1024 is reasonable for now (it's configured per IRCd)
 #define MAXRFCNICKLEN 9 // From RFC 1459
+#define MAXDNSTXTLEN 2048 // Maximum size to store in a DNS TXT record response
+#define VERSIONTXTNAME "version.blabouncer.blatech.net" // DNS name of blabouncer latest version check TXT record
 
 #define MAXTOKENS 100 // For strsep string splitting
 
@@ -220,4 +223,14 @@ void stripprefixesfromnick(char *nick);
 
 // Convert the given 'string' into lowercase
 void strlower(char *string);
+
+// Gets a single TXT record from DNS for "dnsname" and stores the result in "record"
+// Returns 1 on success or 0 on failure
+// TODO: If this is ever used for more than just version checks, then it needs to do more than a single record.
+int gettxtrecordsingle(char *dnsname, char *record);
+
+// Gets the latest blabouncer version string from DNS and stores it in "version"
+// Ignores the Git version portion (everything after the first '-') of VERSION, if present
+// Returns 1 if local VERSION is current, -1 if local VERSION is not current, or 0 on failure
+int checkversion(char *version);
 #endif
diff --git a/message.c b/message.c
index f8e14cb..f580419 100644
--- a/message.c
+++ b/message.c
@@ -1033,6 +1033,31 @@ int processclientmessage(SSL *server_ssl, char *str, struct client *clients, int
     // Send our own greeting message
     snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Welcome to blabouncer version %s!", ircdstate->ircnick, VERSION);
     sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
+
+    // Check for updates (if enabled in configuration file with checkupdates = "1")
+    if (settings->checkupdates) {
+      debugprint(DEBUG_FULL, "Checking for blabouncer updates on client connection.\n");
+      char version[MAXDNSTXTLEN];
+      version[0] = '\0';
+      int ret = checkversion(version);
+      if (ret == 1) {
+        snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Blabouncer appears to be up to date.", ircdstate->ircnick);
+        sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
+      } else if (ret == -1) {
+
+        // Next prepare the topic who/when message...
+        if (!snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Blabouncer appears to be out of date, latest version is %s.", ircdstate->ircnick, version)) {
+          fprintf(stderr, "processclientmessage() Error while preparing out of date version warning after client connected (version string too long?)!\n");
+          debugprint(DEBUG_CRIT, "processclientmessage() Error while preparing out of date version warning after client connected (version string too long?)!\n");
+          snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Blabouncer appears to be out of date, but couldn't print latest version in this NOTICE.", ircdstate->ircnick);
+        }
+        sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
+      } else {
+        snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Version check failed!", ircdstate->ircnick);
+        sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
+      }
+    }
+
     snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Blabouncer commands are all prefixed with BLABOUNCER which you can usually send using \"/QUOTE BLABOUNCER\"", ircdstate->ircnick);
     sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
     snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Valid blabouncer commands are:", ircdstate->ircnick);
@@ -1051,6 +1076,8 @@ int processclientmessage(SSL *server_ssl, char *str, struct client *clients, int
     sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
     snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :\"BLABOUNCER VERSION\" (To show the current blabouncer version.)", ircdstate->ircnick);
     sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
+    snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :\"BLABOUNCER UPDATECHECK\" (To check for blabouncer version updates.)", ircdstate->ircnick);
+    sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
 
     // Get the channel count so we can iterate over all channels.
     int channelcount = getchannelcount(channels, ircdstate->maxchannelcount);
@@ -1528,6 +1555,31 @@ int processclientmessage(SSL *server_ssl, char *str, struct client *clients, int
       snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :This is blabouncer version %s!", ircdstate->ircnick, VERSION);
       sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
       return 1;
+    // UPDATECHECK received, send current blabouncer version
+    } else if (strncasecmp(tokens[1], "UPDATECHECK", strlen("UPDATECHECK")) == 0) {
+      debugprint(DEBUG_SOME, "Client BLABOUNCER UPDATECHECK found and it is: %s with length %zd!\n", tokens[1], strlen(tokens[1]));
+
+      char version[MAXDNSTXTLEN];
+      version[0] = '\0';
+      int ret = checkversion(version);
+      if (ret == 1) {
+        snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Blabouncer appears to be up to date.", ircdstate->ircnick);
+        sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
+      } else if (ret == -1) {
+
+        // Next prepare the topic who/when message...
+        if (!snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Blabouncer appears to be out of date, latest version is %s.", ircdstate->ircnick, version)) {
+          fprintf(stderr, "processclientmessage() Error while preparing out of date version warning after client connected (version string too long?)!\n");
+          debugprint(DEBUG_CRIT, "processclientmessage() Error while preparing out of date version warning after client connected (version string too long?)!\n");
+          snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Blabouncer appears to be out of date, but couldn't print latest version in this NOTICE.", ircdstate->ircnick);
+        }
+        sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
+      } else {
+        snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Version check failed!", ircdstate->ircnick);
+        sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
+      }
+
+      return 1;
     // LISTCLIENTS received, send list of connected clients and their authentication status
     } else if (strncasecmp(tokens[1], "LISTCLIENTS", strlen("LISTCLIENTS")) == 0) {
       debugprint(DEBUG_SOME, "Client BLABOUNCER LISTCLIENTS found and it is: %s with length %zd!\n", tokens[1], strlen(tokens[1]));
@@ -1610,6 +1662,8 @@ int processclientmessage(SSL *server_ssl, char *str, struct client *clients, int
       sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
       snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :\"BLABOUNCER VERSION\" (To show the current blabouncer version.)", ircdstate->ircnick);
       sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
+      snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :\"BLABOUNCER UPDATECHECK\" (To check for blabouncer version updates.)", ircdstate->ircnick);
+      sendtoclient(sourcefd, outgoingmsg, clients, settings, 0);
       return 1;
     }
   }
diff --git a/structures.h b/structures.h
index c4d20e0..86f83b7 100644
--- a/structures.h
+++ b/structures.h
@@ -90,6 +90,7 @@ struct settings {
   int alertauthsuccess;
   int alertunautheddisconnect;
   int alertautheddisconnect;
+  int checkupdates;
 };
 
 // Structure of a connected client, their socket/file descriptors, their authentication status, and their OpenSSL structures