feat(feuille.c): handle children exit codes

Will be useful when a batch of static/dynamic analysis tools will
check feuille's code.

config.mk

@@ -18,7 +18,7 @@ LIBS = -L/usr/lib -lc
 CC = cc
 
 # debug build
-CFLAGS  = -g -std=c99 -Wall -Wextra -Wpedantic -Wno-sign-compare -DVERSION=\"$(VERSION)\" $(INCS)
+CFLAGS  = -g -std=c99 -Wall -Wextra -Wpedantic -Wno-sign-compare -DVERSION=\"$(VERSION)\" -DDEBUG $(INCS)
 LDFLAGS = -g $(LIBS)
 
 # release build

feuille.1

@@ -68,13 +68,13 @@ Default: \f[V]/var/www/feuille\f[R]
 .TP
 \f[B]-s bytes\f[R]
 Sets the maximum size for every paste (in bytes).
-Default: \f[V]2097152\f[R]B (2MiB)
+Default: \f[V]1048576\f[R]B (1MiB)
 .TP
 \f[B]-t seconds\f[R]
 Sets the timeout for the client to send the paste (in seconds).
 If set to zero, no timeout is set.
 (Not recommended.)
-Default: \f[V]4\f[R]s
+Default: \f[V]2\f[R]s
 .TP
 \f[B]-u\f[R]
 Sets the user that will be used when dropping root privileges.
@@ -99,7 +99,8 @@ Sets the number of processes that will be spawned to handle the
 connections.
 Those are \f[I]real\f[R] processes, not green / posix threads, you might
 not want to set this to a huge number.
-Default: the number of threads configured on your machine.
+Default: the greater of the number of cores in your computer and
+\f[V]4\f[R] workers.
 .SH EXAMPLES
 .TP
 \f[B]sudo feuille\f[R]

feuille.1.md

@@ -53,12 +53,12 @@ if possible).
 
 **-s bytes**
 : Sets the maximum size for every paste (in bytes).
-: Default: `2097152`B (2MiB)
+: Default: `1048576`B (1MiB)
 
 **-t seconds**
 : Sets the timeout for the client to send the paste (in seconds).
 : If set to zero, no timeout is set. (Not recommended.)
-: Default: `4`s
+: Default: `2`s
 
 **-u**
 : Sets the user that will be used when dropping root privileges.
@@ -83,7 +83,8 @@ client.
 connections.
 : Those are *real* processes, not green / posix threads,
 you might not want to set this to a huge number.
-: Default: the number of threads configured on your machine.
+: Default: the greater of the number of cores in your computer and
+`4` workers.
 
 # EXAMPLES
 

feuille.c

@@ -44,11 +44,11 @@ Settings settings = {
     .user                = "www",
 
     .id_length           = 4,
-    .worker_count        = 1,
+    .worker_count        = 4,
     .port                = 9999,
-    .timeout             = 4,
-    .max_size            = 2097152, /* = 2MiB   = 1024 * 1024 * 2 */
-    .buffer_size         = 131072,  /* = 128KiB = 1024 * 128      */
+    .timeout             = 2,
+    .max_size            = 1048576, /* = 1MiB   = 1024 * 1024 */
+    .buffer_size         = 131072,  /* = 128KiB = 1024 * 128  */
 
     .verbose             = 0,
     .foreground          = 0
@@ -57,6 +57,7 @@ Settings settings = {
 /* functions declarations */
 static  void     usage(int exit_code);
 static  void     version(void);
+static  void     accept_loop(int);
 
 /**
  * Display feuille's basic usage.
@@ -76,6 +77,89 @@ void version(void)
     die(0, "%s %s by Tom MTT. <tom@heimdall.pm>\n", argv0, VERSION);
 }
 
+/**
+ * Feuille's accept loop.
+ *   server: the server socket.
+ */
+void accept_loop(int server)
+{
+    /* get current process' pid */
+    int pid = getpid();
+
+    /* feed the random number god */
+    srand(time(0) + pid);
+
+    /* accept loop */
+    int connection;
+    while ((connection = accept_connection(server))) {
+        verbose(1, "--- new incoming connection. connection ID: %d:%d ---", pid, time(0));
+
+        char *paste = NULL;
+        char *id    = NULL;
+        char *url   = NULL;
+
+        /* read paste from connection */
+        verbose(1, "reading paste from incoming connection...");
+
+        if ((paste = read_paste(connection)) != NULL) {
+            /* generate random ID */
+            verbose(1, "done.");
+            verbose(2, "generating a random ID...");
+
+            if ((id = generate_id(settings.id_length)) != NULL) {
+                /* write paste to disk */
+                verbose(2, "done.");
+                verbose(1, "writing paste `%s' to disk...", id);
+
+                if (write_paste(paste, id) == 0) {
+                    /* create URL */
+                    verbose(1, "done.");
+                    verbose(2, "making the right URL...");
+
+                    if ((url = create_url(id)) != NULL) {
+                        /* send URL */
+                        verbose(2, "done.", url);
+                        verbose(1, "sending the link to the client...");
+
+                        send_response(connection, url);
+
+                        verbose(1, "All done.");
+
+                        free(url);
+                    } else {
+                        error("error while making a valid URL.");
+                        send_response(connection, "Could not create your paste URL.\nPlease try again later.\n");
+                    }
+                } else {
+                    error("error while writing paste to disk.");
+                    send_response(connection, "Could not write your paste to disk.\nPlease try again later.\n");
+                }
+
+                free(id);
+            } else {
+                error("error while generating a random ID.");
+                send_response(connection, "Could not generate your paste ID.\nPlease try again later.\n");
+            }
+
+            free(paste);
+        } else {
+            if (errno == EFBIG)
+                send_response(connection, "Paste too big.\n");
+
+            if (errno == ENOENT)
+                send_response(connection, "Empty paste.\n");
+
+            if (errno == EAGAIN)
+                send_response(connection, "Timeout'd.\n");
+
+            error("error %d while reading paste from incoming connection.", errno);
+        }
+
+        /* close connection */
+        close_connection(connection);
+    }
+}
+
 /**
  * Feuille's main function.
  *   argc: the argument count.
@@ -87,14 +171,18 @@ int main(int argc, char *argv[])
     /* locale */
     setlocale(LC_ALL, "");
 
-    /* syslog setup */
-    openlog("feuille", LOG_NDELAY |  LOG_PERROR, LOG_USER);
+    /* syslog */
+    openlog("feuille", LOG_NDELAY | LOG_PERROR, LOG_USER);
+
+    /* ignore signals that could kill feuille */
+    signal(SIGPIPE, SIG_IGN); /* when send(2) or write(2) fails */
+
 
     /* settings */
     long long tmp;
 
     /* set number of workers */
-    if ((tmp = sysconf(_SC_NPROCESSORS_ONLN)) > 0 && tmp <= USHRT_MAX)
+    if ((tmp = sysconf(_SC_NPROCESSORS_ONLN)) > settings.worker_count && tmp <= USHRT_MAX)
         settings.worker_count = tmp;
 
     ARGBEGIN {
@@ -263,6 +351,7 @@ int main(int argc, char *argv[])
     if ((server = initialize_server()) == -1)
         die(errno, "Failed to initialize server socket: %s\n", strerror(errno));
 
+
     /* make feuille run in the background */
     if (!settings.foreground) {
         verbose(1, "making feuille run in the background...");
@@ -271,11 +360,6 @@ int main(int argc, char *argv[])
         daemon(1, 0);
     }
 
-    /* ignore most signals that could kill feuille */
-    verbose(3, "ignoring signals that could kill feuille...");
-
-    signal(SIGPIPE, SIG_IGN); /* when send(2) or write(2) fails */
-
 
     /* chroot and drop root permissions */
     if (getuid() == 0) {
@@ -293,12 +377,13 @@ int main(int argc, char *argv[])
 
     }
 
+#ifdef __OpenBSD__
     /* OpenBSD-only security measures */
-    #ifdef __OpenBSD__
     pledge("proc stdio rpath wpath cpath inet", "stdio rpath wpath cpath inet");
-    #endif
+#endif
 
 
+#ifndef DEBUG
     /* create a thread pool for incoming connections */
     verbose(1, "initializing worker pool...");
 
@@ -306,95 +391,41 @@ int main(int argc, char *argv[])
     for (int i = 1; i <= settings.worker_count; i++) {
         if ((pid = fork()) == 0) {
             verbose(2, "  worker n. %d...", i);
+            accept_loop(server);
 
-            pid = getpid();
-
-            /* feed the random number god */
-            srand(time(0) + pid);
-
-            /* accept loop */
-            int connection;
-            while ((connection = accept_connection(server))) {
-                verbose(1, "--- new incoming connection. connection ID: %d:%d ---", pid, time(0));
-
-                char *paste = NULL;
-                char *id    = NULL;
-                char *url   = NULL;
-
-                /* read paste from connection */
-                verbose(1, "reading paste from incoming connection...");
-
-                if ((paste = read_paste(connection)) != NULL) {
-                    /* generate random ID */
-                    verbose(1, "done.");
-                    verbose(2, "generating a random ID...");
-
-                    if ((id = generate_id(settings.id_length)) != NULL) {
-                        /* write paste to disk */
-                        verbose(2, "done.");
-                        verbose(1, "writing paste `%s' to disk...", id);
-
-                        if (write_paste(paste, id) == 0) {
-                            /* create URL */
-                            verbose(1, "done.");
-                            verbose(2, "making the right URL...");
-
-                            if ((url = create_url(id)) != NULL) {
-                                verbose(2, "done.", url);
-                                verbose(1, "sending the link to the client...");
-
-                                send_response(connection, url);
-
-                                verbose(1, "All done.");
+        } else if (pid < 0)
+            die(errno, "Could not initialize worker n. %d: %s\n", i, strerror(errno));
+    }
+#else
+    /* do not create a thread pool if in DEBUG mode */
+    verbose(1, "running in DEBUG mode, won't create a worker pool.");
+    accept_loop(server);
+#endif
 
-                                free(url);
-                            } else {
-                                error("error while making a valid URL.");
-                                send_response(connection, "Could not create your paste URL.\nPlease try again later.\n");
-                            }
-                        } else {
-                            error("error while writing paste to disk.");
-                            send_response(connection, "Could not write your paste to disk.\nPlease try again later.\n");
-                        }
 
-                        free(id);
-                    } else {
-                        error("error while generating a random ID.");
-                        send_response(connection, "Could not generate your paste ID.\nPlease try again later.\n");
-                    }
+    sleep(1);
 
-                    free(paste);
-                } else {
-                    if (errno == EFBIG)
-                        send_response(connection, "Paste too big.\n");
+    verbose(1, "all workers have been initialized.");
+    verbose(1, "beginning to accept incoming connections.");
 
-                    if (errno == ENOENT)
-                        send_response(connection, "Empty paste.\n");
 
-                    if (errno == EAGAIN)
-                        send_response(connection, "Timeout'd.\n");
+    /* fork again if a child dies */
+    int status;
+    int child_pid;
+    while ((child_pid = wait(&status)) > 0) {
+        error("child %d unexpectedly died with exit code %d.", child_pid, WEXITSTATUS(status));
 
-                    error("error %d while reading paste from incoming connection.", errno);
-                }
+        /* do not fork if child was KILL'ed */
+        if (WTERMSIG(status) == 9)
+            continue;
 
-                /* close connection */
-                close_connection(connection);
-            }
+        if ((pid = fork()) == 0) {
+            accept_loop(server);
 
         } else if (pid < 0)
-            die(errno, "Could not initialize worker n. %d: %s\n", i, strerror(errno));
+            error("could not fork killed child again: ", strerror(errno));
     }
 
-
-    sleep(1);
-
-    verbose(1, "all workers have been initialized.");
-    verbose(1, "beginning to accept incoming connections.");
-
-    /* wait for children to finish */
-    // TODO: handle children exit codes properly
-    while (wait(0) > 0);
     close(server);
-
     return 0;
 }

server.c

@@ -103,19 +103,19 @@ int initialize_server()
         if (setsockopt(server, SOL_SOCKET, SO_REUSEADDR, &(int){ 1 }, sizeof(int)) < 0)
             return -1;
 
+#ifndef __OpenBSD__
         /* Enable dual-stack mode on supported platforms */
-        #ifndef __OpenBSD__
-            verbose(3, "  IPV6_V6ONLY...");
-            if (setsockopt(server, IPPROTO_IPV6, IPV6_V6ONLY, &ipv6_only, sizeof(ipv6_only)) < 0)
-                return -1;
-        #else
-            if (ipv6_only == 0) {
-                puts("");
-                syslog(LOG_WARNING, "dual-stack mode is disabled on OpenBSD.");
-                syslog(LOG_WARNING, "feuille will only listen on the `::' IPv6 address.");
-                puts("");
-            }
-        #endif
+        verbose(3, "  IPV6_V6ONLY...");
+        if (setsockopt(server, IPPROTO_IPV6, IPV6_V6ONLY, &ipv6_only, sizeof(ipv6_only)) < 0)
+            return -1;
+#else
+        if (ipv6_only == 0) {
+            puts("");
+            syslog(LOG_WARNING, "dual-stack mode is disabled on OpenBSD.");
+            syslog(LOG_WARNING, "feuille will only listen on the `::' IPv6 address.");
+            puts("");
+        }
+#endif
 
         /* bind address and port */
         verbose(3, "binding address on the socket...");