Handle SIGINT (Ctrl-C) and SIGTERM (kill command) cleanly and fix unrelated server reconnect upon send() returning -1 issue.

2 files changed, 75 insertions, 19 deletions

diff --git a/TODO b/TODO
index 81e62bc..2b3b030 100644
--- a/TODO
+++ b/TODO
@@ -9,4 +9,4 @@ Might need to #include <limits.h> in blabouncer.c to make some operating systems
 
 Send a PING to the server before assuming a timeout is definite.
 
-Capture Ctrl-C/kill and exit cleanly.
+Put debug logs in subdirectory and have max number to keep be configurable.
diff --git a/blabouncer.c b/blabouncer.c
index cd50a0a..02c62ad 100644
--- a/blabouncer.c
+++ b/blabouncer.c
@@ -18,6 +18,7 @@
 #include <time.h>
 #include <sys/stat.h>
 #include <limits.h>
+#include <signal.h>
 #include <openssl/ssl.h>
 #include <openssl/err.h>
 #include <openssl/bio.h>
@@ -38,11 +39,14 @@
 #define DEBUG_SOME 1
 #define DEBUG_FULL 2
 
+#define STDIN 0 // stdin is fd 0
+#define SIGINT 2 // SIGINT is signal 2
+#define SIGTERM 15 // SIGTERM is signal 15
+
 // It seems to be that *message length* is max 512 bytes, but a socket read from at least UnrealIRCd seems to be up to at least 2416 (+1 for null) bytes.
 // 1208 bytes with OpenSSL, 2416 bytes with plain text.
 #define MAXRCVSIZE 2417
 #define MAXDATASIZE 513 // max number of bytes we can get at once (RFC2812 says 512, plus one for null terminator)
-#define STDIN 0 // stdin is fd 0
 #define MAXCLIENTS 32 // maximum number of clients that can connect to the bouncer at a time
 #define MAXTOKENS 100 // maximum number of (CRLF or space) separated tokens per server response we expect (TODO - check this is reasonable) (CRLF and spaces just grouped here due to laziness)
 #define MAXPONGSIZE 32 // let's assume PING/PONG responses can't be larger than this (TODO - check this [it's totally made up]!)
@@ -62,6 +66,9 @@
 int debug = 0; // Debug verbosity ("0" for critical only, "1" for some extra info, "2" for full debug mode)
 char debugpath[PATH_MAX]; // Path to debug file
 
+// Set if certain signal (just SIGINT and SIGKILL at time of writing) is received
+int signum = 0;
+
 struct channel {
   char name[MAXCHANLENGTH];
   char topic[MAXDATASIZE]; // TODO - Is there a particular maximum topic length?
@@ -133,6 +140,12 @@ struct client {
   int pendingcap; // Whether the client is still negotiating IRCv3 CAPabilities.  0 = no, 1 = yes, -1 = just finished (so register them as if they had just sent USER).
 };
 
+// Signal handler
+// We don't actually do anything in here, the main pselect() notice signals
+void sighandler(int sig) {
+  signum = sig;
+}
+
 // Return index of requested client FD within the clients array.
 // TODO - Use this wherever we are calculating the position (various places) instead of
 // duplicating code.
@@ -762,6 +775,30 @@ int connecttoircserver(SSL_CTX **serverctx, SSL **server_ssl, int *serversockfd,
   return 1; // TODO - Return 0 if this fails and make callers do something with that
 }
 
+// Exit the program cleanly - tell clients, tell the server, then exit(0)
+// Optional quit message string "quitmsg"
+// "sourcefd" of 0 means the request didn't come from a client
+void cleanexit(SSL *server_ssl, struct client *clients, int sourcefd, struct ircdstrings *ircdstrings, struct settings *settings, char *quitmsg) {
+  char outgoingmsg[MAXDATASIZE];
+
+  // Tell clients and debug log
+  if (sourcefd) {
+    snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Exiting on request from client with fd '%d', message '%s'.", ircdstrings->ircnick, sourcefd, quitmsg);
+    debugprint(DEBUG_CRIT, "Exiting on request from client with fd '%d', message '%s'.\n", sourcefd, quitmsg);
+  } else {
+    snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Exiting on request (not from a client), message '%s'.", ircdstrings->ircnick, quitmsg);
+    debugprint(DEBUG_CRIT, "Exiting on request (not from a client), message '%s'.\n", quitmsg);
+  }
+  sendtoallclients(clients, outgoingmsg, EXCEPT_NONE, settings);
+
+  // Tell the server
+  // Combine "QUIT :" with any (optional) quit message
+  snprintf(outgoingmsg, MAXDATASIZE, "QUIT :%s", quitmsg);
+  sendtoserver(server_ssl, outgoingmsg, strlen(outgoingmsg), sourcefd, clients, settings);
+
+  exit(0);
+}
+
 // Figure out what to do with each CRLF-split IRC message (if anything)
 // by splitting out the different components by space character (ASCII 0x20).
 //
@@ -2078,20 +2115,14 @@ int processircmessage(SSL *server_ssl, char *str, int source, struct client *cli
         // QUIT received, send QUIT message to server and exit cleanly
         } else if (strncasecmp(tokens[1], "QUIT", strlen("QUIT")) == 0) {
           debugprint(DEBUG_SOME, "Client BLABOUNCER QUIT found and it is: %s with length %zd!\n", tokens[1], strlen(tokens[1]));
-          snprintf(outgoingmsg, MAXDATASIZE, "NOTICE %s :Exiting on BLABOUNCER QUIT command from client with fd '%d'.", ircdstrings->ircnick, sourcefd);
-          sendtoallclients(clients, outgoingmsg, EXCEPT_NONE, settings);
           // Combine "QUIT :" with any optional quit message the user provided
-          char quitmsg[MAXDATASIZE];
           if (counter > 2) {
             // Any optional quit message comes 16 characters after the start of the string ("BLABOUNCER QUIT " is 16 characters)
-            snprintf(quitmsg, MAXDATASIZE, "QUIT :%s", str + 16);
+            cleanexit(server_ssl, clients, sourcefd, ircdstrings, settings, str + 16);
           } else {
-            snprintf(quitmsg, MAXDATASIZE, "QUIT");
+            cleanexit(server_ssl, clients, sourcefd, ircdstrings, settings, "");
           }
-          sendtoserver(server_ssl, quitmsg, strlen(quitmsg), sourcefd, clients, settings);
-          debugprint(DEBUG_CRIT, "Exiting on client request.\n");
-          free(strcopyPtr);
-          exit(0);
+
         // Unrecognised BLABOUNCER command received, send some help instructions
         } else {
           debugprint(DEBUG_SOME, "Client BLABOUNCER unrecognised command found and it is: %s with length %zd!  Sending a help message.\n", tokens[1], strlen(tokens[1]));
@@ -2253,7 +2284,7 @@ void dochat(int *serversockfd, int *clientsockfd, struct settings *settings) {
 
   fdmax = *clientsockfd; // keep track of highest fd number, currently client socket as created last (after server socket)
 
-  fd_set rfds; // set of read fds to monitor with select() - 0: stdin, 1: stdout, 2: stderr, 3 and higher: sockets (at time of writing, 3: real IRC server, 4: client listener, 5 and higher: clients)
+  fd_set rfds; // set of read fds to monitor with pselect() - 0: stdin, 1: stdout, 2: stderr, 3 and higher: sockets (at time of writing, 3: real IRC server, 4: client listener, 5 and higher: clients)
 
   // Set up clients structure
   struct client clients[MAXCLIENTS];
@@ -2307,6 +2338,18 @@ void dochat(int *serversockfd, int *clientsockfd, struct settings *settings) {
     configure_openssl_context(ctx, settings->certfile, settings->keyfile);
   }
 
+  // Let's set up signal handling stuff here since we're about to enter The Big Loop (TM)
+  // We'll handle SIGINT (Ctrl-C) and SIGTERM (default signal of `kill`)
+  signal(SIGINT, sighandler); // SIGINT (2)
+  signal(SIGTERM, sighandler); // SIGTERM (15)
+
+  // Block those two signals
+  sigset_t sigset, oldset;
+  sigemptyset(&sigset);
+  sigaddset(&sigset, SIGINT);
+  sigaddset(&sigset, SIGTERM);
+  sigprocmask(SIG_BLOCK, &sigset, &oldset);
+
   while (1) {
     debugprint(DEBUG_FULL, "top of loop, fdmax %d.\n", fdmax);
     FD_ZERO(&rfds); // clear entries from fd set
@@ -2355,12 +2398,26 @@ void dochat(int *serversockfd, int *clientsockfd, struct settings *settings) {
       continue;
     }
 
-    debugprint(DEBUG_FULL, "select()ing...\n");
-    // check to see if anything in the fd_set is waiting - waits here until one of the fds in the set does something
-    if (select(fdmax + 1, &rfds, NULL, NULL, NULL) < 0) { // network socket + 1, rfds, no writes, no exceptions/errors, no timeout
-      perror("select");
-      debugprint(DEBUG_CRIT, "select() error, errno '%d'.\n", errno);
-      continue;
+    debugprint(DEBUG_FULL, "pselect()ing...\n");
+    // Check to see if any fd in the fd_set is waiting or a signal happened - blocks here until one one of those things happens
+    // (pselect() to do signal handling in additiona to fd monitoring)
+    if (pselect(fdmax + 1, &rfds, NULL, NULL, NULL, &oldset) < 0) { // network socket + 1, rfds, no writes, no exceptions/errors, no timeout, original sigmask
+      if (errno == EINTR) {
+        // Signal caught, do signal handling
+        debugprint(DEBUG_CRIT, "signal '%d' happened, exiting!\n", signum);
+        if (signum == SIGINT) {
+          cleanexit(server_ssl, clients, 0, &ircdstrings, settings, "SIGINT received");
+        } else if (signum == SIGTERM) {
+          cleanexit(server_ssl, clients, 0, &ircdstrings, settings, "SIGTERM received");
+        } else {
+          cleanexit(server_ssl, clients, 0, &ircdstrings, settings, "Unexpected signal received");
+        }
+      } else {
+        // Some other error
+        perror("pselect");
+        debugprint(DEBUG_CRIT, "pselect() error, errno '%d'.\n", errno);
+        continue;
+      }
     }
 
     // TODO - switch around the serversockfd and STDIN FD_ISSET if-statements?  They feel the wrong way round.  Are they like this on purpose?  I can't remember.
@@ -2374,7 +2431,6 @@ void dochat(int *serversockfd, int *clientsockfd, struct settings *settings) {
         perror("recv");
         printf("receive error (-1), skipping loop iteration...\n");
         debugprint(DEBUG_CRIT, "serversockfd receive error (-1), skipping loop iteration, errno '%d'.\n");
-        continue;
       } else if (servernumbytes == 0) {
         perror("recv");
         printf("socket closed (or no data received) (0), skipping loop iteration...\n");