Example of making the first line special

Makefile

@@ -3,18 +3,9 @@ CC      = cc
 CFLAGS  = -std=c99 -Wall -Wextra -Wno-missing-field-initializers -Os
 LDFLAGS = -ggdb3
 LDLIBS  =
-PREFIX  = /usr/local
-
-all: endlessh
 
 endlessh: endlessh.c
 	$(CC) $(LDFLAGS) $(CFLAGS) -o $@ endlessh.c $(LDLIBS)
 
-install: endlessh
-	install -d $(DESTDIR)$(PREFIX)/bin
-	install -m 755 endlessh $(DESTDIR)$(PREFIX)/bin/
-	install -d $(DESTDIR)$(PREFIX)/share/man/man1
-	install -m 644 endlessh.1 $(DESTDIR)$(PREFIX)/share/man/man1/
-
 clean:
 	rm -rf endlessh

README.md

@@ -19,8 +19,6 @@ Usage information is printed with `-h`.
 
 ```
 Usage: endlessh [-vh] [-d MS] [-f CONFIG] [-l LEN] [-m LIMIT] [-p PORT]
-  -4        Bind to IPv4 only
-  -6        Bind to IPv6 only
   -d INT    Message millisecond delay [10000]
   -f        Set and load config file [/etc/endlessh/config]
   -h        Print this help message and exit
@@ -45,8 +43,6 @@ write a complete, consistent log.
 
 A SIGHUP signal requests a reload of the configuration file (`-f`).
 
-A SIGUSR1 signal will print connections stats to the log.
-
 ## Sample Configuration File
 
 The configuration file has similar syntax to OpenSSH.
@@ -73,40 +69,15 @@ MaxClients 4096
 #   1 = Standard, useful log messages
 #   2 = Very noisy debugging information
 LogLevel 0
-
-# Set the family of the listening socket
-#   0 = Use IPv4 Mapped IPv6 (Both v4 and v6, default)
-#   4 = Use IPv4 only
-#   6 = Use IPv6 only
-BindFamily 0
 ```
 
 ## Build issues
 
-Some more esoteric systems require extra configuration when building.
-
-### RHEL 6 / CentOS 6
-
-This system uses a version of glibc older than 2.17 (December 2012), and
-`clock_gettime(2)` is still in librt. For these systems you will need to
-link against librt:
+RHEL 6 and CentOS 6 use a version of glibc older than 2.17 (December
+2012), and `clock_gettime(2)` is still in librt. For these systems you
+will need to link against librt:
 
     make LDLIBS=-lrt
 
-### Solaris / illumos
-
-These systems don't include all the necessary functionality in libc and
-the linker requires some extra libraries:
-
-    make CC=gcc LDLIBS='-lnsl -lrt -lsocket'
-
-If you're not using GCC or Clang, also override `CFLAGS` and `LDFLAGS`
-to remove GCC-specific options. For example, on Solaris:
-
-    make CFLAGS=-fast LDFLAGS= LDLIBS='-lnsl -lrt -lsocket'
-
-The feature test macros on these systems isn't reliable, so you may also
-need to use `-D__EXTENSIONS__` in `CFLAGS`.
-
 
 [np]: https://nullprogram.com/blog/2019/03/22/

endlessh.1

@@ -1,81 +0,0 @@
-.Dd $Mdocdate: April 12 2019 $
-.Dt ENDLESSH 1
-.Os
-.Sh NAME
-.Nm endless
-.Nd An SSH tarpit
-.Sh SYNOPSIS
-.Nm endless
-.Op Fl 46chvV
-.Op Fl d Ar delay
-.Op Fl f Ar config
-.Op Fl l Ar max banner length
-.Op Fl m Ar max clients
-.Op Fl p Ar port
-.Sh DESCRIPTION
-.Nm
-is an SSH tarpit that very slowly
-sends an endless, random SSH banner.
-.Pp
-.Nm
-keeps SSH clients locked up for hours or even days at a time.
-The purpose is to put your real SSH server on another port
-and then let the script kiddies get stuck in this tarpit
-instead of bothering a real server.
-.Pp
-Since the tarpit is in the banner before any cryptographic
-exchange occurs, this program doesn't depend on any cryptographic
-libraries. It's a simple, single-threaded, standalone C program.
-It uses poll() to trap multiple clients at a time.
-.Pp
-The options are as follows:
-.Bl -tag -width Ds
-.It Fl 4
-Forces
-.Nm
-to use IPv4 addresses only.
-.It Fl 6
-Forces
-.Nm
-to use IPv6 addresses only.
-.It Fl d Ar delay
-Message milliseconds delay. Default: 10000
-.It Fl f Ar config
-Set and load config file.
-By default
-.Nm
-looks for /etc/endlessh/config.
-.It Fl h
-Print the help message and exit.
-.It Fl l Ar max banner length
-Maximum banner line length (3-255). Default: 32
-.It Fl m Ar max clients
-Maximum number of clients. Default: 4096
-.It Fl p Ar port
-Set the listening port. By default
-.Nm
-listens on port 2222.
-.It Fl v
-Print diagnostics to standard output. Can be specified
-numerous times to increase verbosity.
-.It Fl V
-Causes
-.Nm
-to print version information and exit.
-.El
-.El
-.Pp
-If
-.Nm
-receives the SIGTERM signal it will gracefully shut
-down the daemon, allowing it to write a complete, consistent log.
-.Pp
-A SIGHUP signal requests a reload of its configuration file.
-.Pp
-A SIGUSR1 signal will print connections stats to the log.
-.Sh FILES
-.Bl -tag -width /etc/endlessh/config -compact
-.It Pa /etc/endlessh/config
-The default
-.Nm
-configuration file.

endlessh.c

@@ -1,4 +1,22 @@
-#define _XOPEN_SOURCE 600
+#ifdef __FreeBSD__
+#  define _WITH_GETLINE
+/* The MSG_DONTWAIT send(2) flag is non-standard, but widely available.
+ * However, FreeBSD doesn't define this flag when using POSIX feature
+ * test macros. Normally feature test macros are required to expose
+ * POSIX functionality, though FreeBSD isn't strict about this. In a
+ * sense it's technically correct to hide a non-standard flag when
+ * asking for strict standards compliance, but this behavior makes this
+ * flag impossible to use in portable programs, at least without this
+ * sort of special case.
+ *
+ * To get the prototype for getline(3), we need either a POSIX feature
+ * test macro or use the FreeBSD-specific _WITH_GETLINE macro. Since we
+ * can't use the former, we'll have to go with the latter.
+ */
+#else
+#  define _POSIX_C_SOURCE 200809L
+#endif
+
 #include <time.h>
 #include <errno.h>
 #include <stdio.h>
@@ -9,27 +27,28 @@
 #include <string.h>
 
 #include <poll.h>
-#include <fcntl.h>
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <arpa/inet.h>
 #include <netinet/in.h>
 
-#define ENDLESSH_VERSION           1.0
+#define ENDLESSH_VERSION           0.1
 
 #define DEFAULT_PORT              2222
 #define DEFAULT_DELAY            10000  /* milliseconds */
 #define DEFAULT_MAX_LINE_LENGTH     32
 #define DEFAULT_MAX_CLIENTS       4096
 #define DEFAULT_CONFIG_FILE      "/etc/endlessh/config"
-#define DEFAULT_BIND_FAMILY  AF_UNSPEC
+
+#define FLAG_SPECIAL_SENT     (1 << 0)
+#define SPECIAL_MESSAGE       "Stay awhile and listen\r\n"
 
 #define XSTR(s) STR(s)
 #define STR(s) #s
 
 static long long
-epochms(void)
+uepoch(void)
 {
     struct timespec tv;
     clock_gettime(CLOCK_REALTIME, &tv);
@@ -49,7 +68,7 @@ logmsg(enum loglevel level, const char *format, ...)
         int save = errno;
 
         /* Print a timestamp */
-        long long now = epochms();
+        long long now = uepoch();
         time_t t = now / 1000;
         char date[64];
         struct tm tm[1];
@@ -67,12 +86,6 @@ logmsg(enum loglevel level, const char *format, ...)
     }
 }
 
-struct {
-    long long connects;
-    long long milliseconds;
-    long long bytes_sent;
-} statistics;
-
 struct client {
     char ipaddr[INET6_ADDRSTRLEN];
     long long connect_time;
@@ -81,6 +94,7 @@ struct client {
     struct client *next;
     int port;
     int fd;
+    int flags;
 };
 
 static struct client *
@@ -89,12 +103,12 @@ client_new(int fd, long long send_next)
     struct client *c = malloc(sizeof(*c));
     if (c) {
         c->ipaddr[0] = 0;
-        c->connect_time = epochms();
+        c->connect_time = uepoch();
         c->send_next = send_next;
         c->bytes_sent = 0;
         c->next = 0;
         c->fd = fd;
-        c->port = 0;
+        c->flags = 0;
 
         /* Set the smallest possible recieve buffer. This reduces local
          * resource usage and slows down the remote end.
@@ -129,57 +143,59 @@ static void
 client_destroy(struct client *client)
 {
     logmsg(LOG_DEBUG, "close(%d)", client->fd);
-    long long dt = epochms() - client->connect_time;
+    long long dt = uepoch() - client->connect_time;
     logmsg(LOG_INFO,
             "CLOSE host=%s port=%d fd=%d "
             "time=%lld.%03lld bytes=%lld",
             client->ipaddr, client->port, client->fd,
             dt / 1000, dt % 1000,
             client->bytes_sent);
-    statistics.milliseconds += dt;
     close(client->fd);
     free(client);
 }
 
-static void
-statistics_log_totals(struct client *clients)
-{
-    long long milliseconds = statistics.milliseconds;
-    for (long long now = epochms(); clients; clients = clients->next)
-        milliseconds += now - clients->connect_time;
-    logmsg(LOG_INFO, "TOTALS connects=%lld seconds=%lld.%03lld bytes=%lld",
-           statistics.connects,
-           milliseconds / 1000,
-           milliseconds % 1000,
-           statistics.bytes_sent);
-}
-
-struct fifo {
+struct queue {
     struct client *head;
     struct client *tail;
     int length;
 };
 
 static void
-fifo_init(struct fifo *q)
+queue_init(struct queue *q)
 {
     q->head = q->tail = 0;
     q->length = 0;
 }
 
 static struct client *
-fifo_pop(struct fifo *q)
+queue_remove(struct queue *q, int fd)
 {
-    struct client *removed = q->head;
-    q->head = q->head->next;
-    removed->next = 0;
-    if (!--q->length)
-        q->tail = 0;
-    return removed;
+    /* Yes, this is a linear search, but the element we're looking for
+     * is virtually always one of the first few elements.
+     */
+    struct client *c;
+    struct client *prev = 0;
+    for (c = q->head; c; prev = c, c = c->next) {
+        if (c->fd == fd) {
+            if (!--q->length) {
+                q->head = q->tail = 0;
+            } else if (q->tail == c) {
+                q->tail = prev;
+                prev->next = 0;
+            } else if (prev) {
+                prev->next = c->next;
+            } else {
+                q->head = c->next;
+            }
+            c->next = 0;
+            break;
+        }
+    }
+    return c;
 }
 
 static void
-fifo_append(struct fifo *q, struct client *c)
+queue_append(struct queue *q, struct client *c)
 {
     if (!q->tail) {
         q->head = q->tail = c;
@@ -191,7 +207,7 @@ fifo_append(struct fifo *q, struct client *c)
 }
 
 static void
-fifo_destroy(struct fifo *q)
+queue_destroy(struct queue *q)
 {
     struct client *c = q->head;
     while (c) {
@@ -203,6 +219,56 @@ fifo_destroy(struct fifo *q)
     q->length = 0;
 }
 
+struct pollvec {
+    size_t cap;
+    size_t fill;
+    struct pollfd *fds;
+};
+
+static void
+pollvec_init(struct pollvec *v)
+{
+    v->cap = 4;
+    v->fill = 0;
+    v->fds = malloc(v->cap * sizeof(v->fds[0]));
+    if (!v->fds) {
+        fprintf(stderr, "endlessh: pollvec initialization failed\n");
+        exit(EXIT_FAILURE);
+    }
+}
+
+static void
+pollvec_clear(struct pollvec *v)
+{
+    v->fill = 0;
+}
+
+static int
+pollvec_push(struct pollvec *v, int fd, short events)
+{
+    if (v->cap == v->fill) {
+        size_t size = v->cap * 2 * sizeof(v->fds[0]);
+        if (size < v->cap * sizeof(v->fds[0]))
+            return 0; // overflow
+        struct pollfd *grow = realloc(v->fds, size);
+        if (!grow)
+            return 0;
+        v->fds = grow;
+        v->cap *= 2;
+    }
+    v->fds[v->fill].fd = fd;
+    v->fds[v->fill].events = events;
+    v->fill++;
+    return 1;
+}
+
+static void
+pollvec_free(struct pollvec *v)
+{
+    free(v->fds);
+    v->fds = 0;
+}
+
 static void
 die(void)
 {
@@ -248,21 +314,11 @@ sighup_handler(int signal)
     reload = 1;
 }
 
-static volatile sig_atomic_t dumpstats = 0;
-
-static void
-sigusr1_handler(int signal)
-{
-    (void)signal;
-    dumpstats = 1;
-}
-
 struct config {
     int port;
     int delay;
     int max_line_length;
     int max_clients;
-    int bind_family;
 };
 
 #define CONFIG_DEFAULT { \
@@ -270,7 +326,6 @@ struct config {
     .delay           = DEFAULT_DELAY, \
     .max_line_length = DEFAULT_MAX_LINE_LENGTH, \
     .max_clients     = DEFAULT_MAX_CLIENTS, \
-    .bind_family     = DEFAULT_BIND_FAMILY, \
 }
 
 static void
@@ -333,27 +388,6 @@ config_set_max_line_length(struct config *c, const char *s, int hardfail)
     }
 }
 
-static void
-config_set_bind_family(struct config *c, const char *s, int hardfail)
-{
-  switch (*s) {
-      case '4':
-          c->bind_family = AF_INET;
-          break;
-      case '6':
-          c->bind_family = AF_INET6;
-          break;
-      case '0':
-          c->bind_family = AF_UNSPEC;
-          break;
-      default:
-          fprintf(stderr, "endlessh: Invalid address family: %s\n", s);
-          if (hardfail)
-              exit(EXIT_FAILURE);
-          break;
-  }
-}
-
 enum config_key {
     KEY_INVALID,
     KEY_PORT,
@@ -361,7 +395,6 @@ enum config_key {
     KEY_MAX_LINE_LENGTH,
     KEY_MAX_CLIENTS,
     KEY_LOG_LEVEL,
-    KEY_BIND_FAMILY,
 };
 
 static enum config_key
@@ -373,7 +406,6 @@ config_key_parse(const char *tok)
         [KEY_MAX_LINE_LENGTH] = "MaxLineLength",
         [KEY_MAX_CLIENTS]     = "MaxClients",
         [KEY_LOG_LEVEL]       = "LogLevel",
-        [KEY_BIND_FAMILY]     = "BindFamily"
     };
     for (size_t i = 1; i < sizeof(table) / sizeof(*table); i++)
         if (!strcmp(tok, table[i]))
@@ -387,8 +419,9 @@ config_load(struct config *c, const char *file, int hardfail)
     long lineno = 0;
     FILE *f = fopen(file, "r");
     if (f) {
-        char line[256];
-        while (fgets(line, sizeof(line), f)) {
+        size_t len = 0;
+        char *line = 0;
+        while (getline(&line, &len, f) != -1) {
             lineno++;
 
             /* Remove comments */
@@ -440,9 +473,6 @@ config_load(struct config *c, const char *file, int hardfail)
                 case KEY_MAX_CLIENTS:
                     config_set_max_clients(c, tokens[1], hardfail);
                     break;
-                case KEY_BIND_FAMILY:
-                    config_set_bind_family(c, tokens[1], hardfail);
-                    break;
                 case KEY_LOG_LEVEL: {
                     errno = 0;
                     char *end;
@@ -458,6 +488,7 @@ config_load(struct config *c, const char *file, int hardfail)
             }
         }
 
+        free(line);
         fclose(f);
     }
 }
@@ -469,19 +500,13 @@ config_log(const struct config *c)
     logmsg(LOG_INFO, "Delay %ld", c->delay);
     logmsg(LOG_INFO, "MaxLineLength %d", c->max_line_length);
     logmsg(LOG_INFO, "MaxClients %d", c->max_clients);
-    logmsg(LOG_INFO, "BindFamily %s",
-        c->bind_family == AF_INET6 ? "IPv6 Only" :
-        c->bind_family == AF_INET  ? "IPv4 Only" :
-                                "IPv4 Mapped IPv6");
 }
 
 static void
 usage(FILE *f)
 {
-    fprintf(f, "Usage: endlessh [-vh] [-46] [-d MS] [-f CONFIG] [-l LEN] "
+    fprintf(f, "Usage: endlessh [-vh] [-d MS] [-f CONFIG] [-l LEN] "
                                "[-m LIMIT] [-p PORT]\n");
-    fprintf(f, "  -4        Bind to IPv4 only\n");
-    fprintf(f, "  -6        Bind to IPv6 only\n");
     fprintf(f, "  -d INT    Message millisecond delay ["
             XSTR(DEFAULT_DELAY) "]\n");
     fprintf(f, "  -f        Set and load config file ["
@@ -504,11 +529,11 @@ print_version(void)
 }
 
 static int
-server_create(int port, int family)
+server_create(int port)
 {
     int r, s, value;
 
-    s = socket(family == AF_UNSPEC ? AF_INET6 : family, SOCK_STREAM, 0);
+    s = socket(AF_INET6, SOCK_STREAM, 0);
     logmsg(LOG_DEBUG, "socket() = %d", s);
     if (s == -1) die();
 
@@ -519,37 +544,12 @@ server_create(int port, int family)
     if (r == -1)
         logmsg(LOG_DEBUG, "errno = %d, %s", errno, strerror(errno));
 
-    /*
-     * With OpenBSD IPv6 sockets are always IPv6-only, so the socket option
-     * is read-only (not modifiable).
-     * http://man.openbsd.org/ip6#IPV6_V6ONLY
-     */
-#ifndef __OpenBSD__
-    if (family == AF_INET6 || family == AF_UNSPEC) {
-        errno = 0;
-        value = (family == AF_INET6);
-        r = setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, &value, sizeof(value));
-        logmsg(LOG_DEBUG, "setsockopt(%d, IPV6_V6ONLY, true) = %d", s, r);
-        if (r == -1)
-            logmsg(LOG_DEBUG, "errno = %d, %s", errno, strerror(errno));
-    }
-#endif
-
-    if (family == AF_INET) {
-        struct sockaddr_in addr4 = {
-            .sin_family = AF_INET,
-            .sin_port = htons(port),
-            .sin_addr = {INADDR_ANY}
-        };
-        r = bind(s, (void *)&addr4, sizeof(addr4));
-    } else {
-        struct sockaddr_in6 addr6 = {
-            .sin6_family = AF_INET6,
-            .sin6_port = htons(port),
-            .sin6_addr = in6addr_any
-        };
-        r = bind(s, (void *)&addr6, sizeof(addr6));
-    }
+    struct sockaddr_in6 addr = {
+        .sin6_family = AF_INET6,
+        .sin6_port = htons(port),
+        .sin6_addr = in6addr_any
+    };
+    r = bind(s, (void *)&addr, sizeof(addr));
     logmsg(LOG_DEBUG, "bind(%d, port=%d) = %d", s, port, r);
     if (r == -1) die();
 
@@ -560,33 +560,6 @@ server_create(int port, int family)
     return s;
 }
 
-/* Write a line to a client, returning client if it's still up. */
-static struct client *
-sendline(struct client *client, int max_line_length, unsigned long *rng)
-{
-    char line[256];
-    int len = randline(line, max_line_length, rng);
-    for (;;) {
-        ssize_t out = write(client->fd, line, len);
-        logmsg(LOG_DEBUG, "write(%d) = %d", client->fd, (int)out);
-        if (out == -1) {
-            if (errno == EINTR) {
-                continue;      /* try again */
-            } else if (errno == EAGAIN || errno == EWOULDBLOCK) {
-                return client; /* don't care */
-            } else {
-                client_destroy(client);
-                return 0;
-            }
-        } else {
-            client->bytes_sent += out;
-            statistics.bytes_sent += out;
-            return client;
-        }
-    }
-}
-
-
 int
 main(int argc, char **argv)
 {
@@ -595,14 +568,8 @@ main(int argc, char **argv)
     config_load(&config, config_file, 1);
 
     int option;
-    while ((option = getopt(argc, argv, "46d:f:hl:m:p:vV")) != -1) {
+    while ((option = getopt(argc, argv, "d:f:hl:m:p:vV")) != -1) {
         switch (option) {
-            case '4':
-                config_set_bind_family(&config, "4", 1);
-                break;
-            case '6':
-                config_set_bind_family(&config, "6", 1);
-                break;
             case 'd':
                 config_set_delay(&config, optarg, 1);
                 break;
@@ -624,7 +591,8 @@ main(int argc, char **argv)
                 config_set_port(&config, optarg, 1);
                 break;
             case 'v':
-                loglevel++;
+                if (!loglevel++)
+                    setvbuf(stdout, 0, _IOLBF, 0);
                 break;
             case 'V':
                 print_version();
@@ -641,9 +609,6 @@ main(int argc, char **argv)
         exit(EXIT_FAILURE);
     }
 
-    /* Set output (log) to line buffered */
-    setvbuf(stdout, 0, _IOLBF, 0);
-
     /* Log configuration */
     config_log(&config);
 
@@ -661,60 +626,53 @@ main(int argc, char **argv)
         if (r == -1)
             die();
     }
-    {
-        struct sigaction sa = {.sa_handler = sigusr1_handler};
-        int r = sigaction(SIGUSR1, &sa, 0);
-        if (r == -1)
-            die();
-    }
 
-    struct fifo fifo[1];
-    fifo_init(fifo);
+    struct queue queue[1];
+    queue_init(queue);
 
-    unsigned long rng = epochms();
+    struct pollvec pollvec[1];
+    pollvec_init(pollvec);
 
-    int server = server_create(config.port, config.bind_family);
+    unsigned long rng = uepoch();
+
+    int server = server_create(config.port);
 
     while (running) {
         if (reload) {
             /* Configuration reload requested (SIGHUP) */
             int oldport = config.port;
-            int oldfamily = config.bind_family;
             config_load(&config, config_file, 0);
             config_log(&config);
-            if (oldport != config.port || oldfamily != config.bind_family) {
+            if (oldport != config.port) {
                 close(server);
-                server = server_create(config.port, config.bind_family);
+                server = server_create(config.port);
             }
             reload = 0;
         }
-        if (dumpstats) {
-            /* print stats requested (SIGUSR1) */
-            statistics_log_totals(fifo->head);
-            dumpstats = 0;
-        }
+
+        /* Enqueue the listening socket first */
+        pollvec_clear(pollvec);
+        if (queue->length < config.max_clients)
+            pollvec_push(pollvec, server, POLLIN);
+        else
+            pollvec_push(pollvec, -1, 0);
 
         /* Enqueue clients that are due for another message */
         int timeout = -1;
-        long long now = epochms();
-        while (fifo->head) {
-            if (fifo->head->send_next <= now) {
-                struct client *c = fifo_pop(fifo);
-                if (sendline(c, config.max_line_length, &rng)) {
-                    c->send_next = now + config.delay;
-                    fifo_append(fifo, c);
-                }
+        long long now = uepoch();
+        for (struct client *c = queue->head; c; c = c->next) {
+            if (c->send_next <= now) {
+                pollvec_push(pollvec, c->fd, POLLOUT);
             } else {
-                timeout = fifo->head->send_next - now;
+                timeout = c->send_next - now;
                 break;
             }
         }
 
         /* Wait for next event */
-        struct pollfd fds = {server, POLLIN, 0};
-        int nfds = fifo->length < config.max_clients;
-        logmsg(LOG_DEBUG, "poll(%d, %d)", nfds, timeout);
-        int r = poll(&fds, nfds, timeout);
+        logmsg(LOG_DEBUG, "poll(%zu, %d)%s", pollvec->fill, timeout,
+                queue->length >= config.max_clients ? " (no accept)" : "");
+        int r = poll(pollvec->fds, pollvec->fill, timeout);
         logmsg(LOG_DEBUG, "= %d", r);
         if (r == -1) {
             switch (errno) {
@@ -728,19 +686,18 @@ main(int argc, char **argv)
         }
 
         /* Check for new incoming connections */
-        if (fds.revents & POLLIN) {
+        if (pollvec->fds[0].revents & POLLIN) {
             int fd = accept(server, 0, 0);
             logmsg(LOG_DEBUG, "accept() = %d", fd);
-            statistics.connects++;
             if (fd == -1) {
                 const char *msg = strerror(errno);
                 switch (errno) {
                     case EMFILE:
                     case ENFILE:
-                        config.max_clients = fifo->length;
+                        config.max_clients = queue->length;
                         logmsg(LOG_INFO,
                                 "MaxClients %d",
-                                fifo->length);
+                                queue->length);
                         break;
                     case ECONNABORTED:
                     case EINTR:
@@ -754,22 +711,59 @@ main(int argc, char **argv)
                         exit(EXIT_FAILURE);
                 }
             } else {
-                long long send_next = epochms() + config.delay;
+                long long send_next = uepoch() + config.delay / 2;
                 struct client *client = client_new(fd, send_next);
-                int flags = fcntl(fd, F_GETFL, 0);      /* cannot fail */
-                fcntl(fd, F_SETFL, flags | O_NONBLOCK); /* cannot fail */
                 if (!client) {
                     fprintf(stderr, "endlessh: warning: out of memory\n");
                     close(fd);
                 }
-                fifo_append(fifo, client);
+                queue_append(queue, client);
                 logmsg(LOG_INFO, "ACCEPT host=%s port=%d fd=%d n=%d/%d",
                         client->ipaddr, client->port, client->fd,
-                        fifo->length, config.max_clients);
+                        queue->length, config.max_clients);
+            }
+        }
+
+        /* Write lines to ready clients */
+        for (size_t i = 1; i < pollvec->fill; i++) {
+            short fd = pollvec->fds[i].fd;
+            short revents = pollvec->fds[i].revents;
+            struct client *client = queue_remove(queue, fd);
+
+            if (revents & POLLHUP) {
+                client_destroy(client);
+
+            } else if (revents & POLLOUT) {
+                char line[256];
+                int len;
+                if (!(client->flags & FLAG_SPECIAL_SENT)) {
+                    static const char special[] = SPECIAL_MESSAGE;
+                    len = sizeof(special) - 1;
+                    memcpy(line, special, len);
+                    client->flags |= FLAG_SPECIAL_SENT;
+                } else {
+                    len = randline(line, config.max_line_length, &rng);
+                }
+                for (;;) {
+                    /* Don't really care if send is short */
+                    ssize_t out = send(fd, line, len, MSG_DONTWAIT);
+                    if (out == -1 && errno == EINTR) {
+                        continue;  /* try again */
+                    } else if (out == -1) {
+                        client_destroy(client);
+                        break;
+                    } else {
+                        logmsg(LOG_DEBUG, "send(%d) = %d", fd, (int)out);
+                        client->bytes_sent += out;
+                        client->send_next = uepoch() + config.delay;
+                        queue_append(queue, client);
+                        break;
+                    }
+                }
             }
         }
     }
 
-    fifo_destroy(fifo);
-    statistics_log_totals(0);
+    pollvec_free(pollvec);
+    queue_destroy(queue);
 }

util/openbsd/endlessh

@@ -1,9 +0,0 @@
-#!/bin/ksh
-#
-
-daemon="/usr/local/bin/endlessh"
-rc_bg=YES
-
-. /etc/rc.d/rc.subr
-
-rc_cmd $1

util/smf/README

@@ -1,25 +0,0 @@
-Solaris SMF installation
-========================
-
-Before installing SMF:
-
-1. Put endlessh binary to /usr/local/bin
-2. Edit endlessh.conf and put it to /usr/local/etc
-
-To install SMF:
-
-1. Put endlessh.xml to /var/svc/manifest/network
-2. Run svccfg import endlessh.xml
-3. Put init.endlessh to /lib/svc/method
-4. Run svcadm enable endlessh
-
-Note: Log will write to /var/log/endlessh.log by default.
-
-To uninstall SMF:
-
-1. Run svcadm disable endlessh
-2. rm -f /lib/svc/method/init.endlessh
-3. svccfg delete svc:/network/endlessh:default
-4. rm -f /var/svc/manifest/network/endlessh.xml
-
-Enjoy! :)

util/smf/endlessh.conf

@@ -1,27 +0,0 @@
-# The port on which to listen for new SSH connections.
-Port 22
-
-# The endless banner is sent one line at a time. This is the delay
-# in milliseconds between individual lines.
-Delay 10000
-
-# The length of each line is randomized. This controls the maximum
-# length of each line. Shorter lines may keep clients on for longer if
-# they give up after a certain number of bytes.
-MaxLineLength 32
-
-# Maximum number of connections to accept at a time. Connections beyond
-# this are not immediately rejected, but will wait in the queue.
-MaxClients 4096
-
-# Set the detail level for the log.
-#   0 = Quiet
-#   1 = Standard, useful log messages
-#   2 = Very noisy debugging information
-LogLevel 1
-
-# Set the family of the listening socket
-#   0 = Use IPv4 Mapped IPv6 (Both v4 and v6, default)
-#   4 = Use IPv4 only
-#   6 = Use IPv6 only
-BindFamily 0

util/smf/endlessh.xml

@@ -1,96 +0,0 @@
-<?xml version="1.0"?>
-<!DOCTYPE service_bundle SYSTEM "/usr/share/lib/xml/dtd/service_bundle.dtd.1">
-<!--   Manifest-file for endlessh, put this file in
-       /var/svc/manifest/network/endlessh.xml
-       and run #svccfg import /var/svc/manifest/network/endlessh.xml
-       Fixed by Yuri Voinov (C) 2007,2019 -->
-<service_bundle type='manifest' name='endlessh'>
-
-<service
-        name='network/endlessh'
-        type='service'
-        version='1'>
-
-        <create_default_instance enabled='false' />
-
-        <single_instance />
-
-        <dependency name='fs-local'
-                grouping='require_all'
-                restart_on='none'
-                type='service'>
-                <service_fmri
-                        value='svc:/system/filesystem/local' />
-        </dependency>
-
-        <dependency name='net-loopback'
-                grouping='require_all'
-                restart_on='none'
-                type='service'>
-                <service_fmri value='svc:/network/loopback' />
-        </dependency>
-
-        <dependency name='net-physical'
-                grouping='require_all'
-                restart_on='none'
-                type='service'>
-                <service_fmri value='svc:/network/physical' />
-        </dependency>
-
-        <dependency name='utmp'
-                grouping='require_all'
-                restart_on='none'
-                type='service'>
-                <service_fmri value='svc:/system/utmp' />
-        </dependency>
-
-        <dependency name='endlessh_config_data'
-                grouping='require_all'
-                restart_on='refresh'
-                type='path'>
-                <service_fmri value='file://localhost/usr/local/etc/endlessh.conf' />
-        </dependency>
-
-        <exec_method
-                type='method'
-                name='start'
-                exec='/lib/svc/method/init.endlessh %m'
-                timeout_seconds='60'/>
-
-        <exec_method
-                type='method'
-                name='stop'
-                exec=':kill'
-                timeout_seconds='60' />
-
-        <exec_method
-                type='method'
-                name='restart'
-                exec='/lib/svc/method/init.endlessh %m'
-                timeout_seconds='60' />
-
-        <exec_method
-                type='method'
-                name='refresh'
-                exec='/lib/svc/method/init.endlessh %m'
-                timeout_seconds='60' />
-
-        <property_group name='general' type='framework'>
-                <!-- to start stop endlessh -->
-                <propval name='action_authorization' type='astring'
-                        value='solaris.smf.manage' />
-        </property_group>
-
-        <stability value='Unstable' />
-
-        <template>
-                <common_name>
-                        <loctext xml:lang='C'>
-                        endlessh service
-                        </loctext>
-                </common_name>
-        </template>
-
-</service>
-
-</service_bundle>

util/smf/init.endlessh

@@ -1,137 +0,0 @@
-#!/sbin/sh
-
-#
-# Control Method for endlessh (/lib/svc/method/init.endlessh)
-# Written by Yuri Voinov (C) 2007,2019
-#
-# ident "@(#)endlessh.sh    1.8    19/27/03 YV"
-#
-
-#############
-# Variables #
-#############
-
-# Base installation directory
-BASE_DIR="/usr/local"
-BASE_CONFIG_DIR=$BASE_DIR"/etc"
-
-# endlessh files paths  
-ENDLESSH_PATH="$BASE_DIR""/bin"
-ENDLESSH_CONF_PATH="$BASE_CONFIG_DIR"
-
-# endlessh files
-ENDLESSH_BIN_FILE="endlessh"
-ENDLESSH_CONF_FILE=$ENDLESSH_BIN_FILE".conf"
-
-# Daemon settings
-ENDLESSH_CONF="$ENDLESSH_CONF_PATH/$ENDLESSH_CONF_FILE"
-
-# Log
-LOG_DIR="/var/log"
-LOGFILE=$LOG_DIR/$ENDLESSH_BIN_FILE".log"
-
-#   
-# OS Commands location variables
-#
-CUT=`which cut`
-ECHO=`which echo`
-KILL=`which kill`
-PGREP=`which pgrep`
-UNAME=`which uname`
-
-# OS release
-OS_VER=`$UNAME -r|$CUT -f2 -d"."`
-OS_NAME=`$UNAME -s|$CUT -f1 -d" "`
-
-###############
-# Subroutines #
-###############
-
-check_endlessh ()
-{
- # Check endlessh installed
- program=$1
- if [ ! -f "$ENDLESSH_PATH/$program" -a ! -x "$ENDLESSH_PATH/$program" ]; then
-  $ECHO "ERROR: endlessh not found!"
-  $ECHO "Exiting..."
-  exit 1
- fi
-}
-
-check_os ()
-{
- # Check OS version
- if [ ! "$OS_NAME" = "SunOS" -a ! "$OS_VER" -lt "10" ]; then
-  $ECHO "ERROR: Unsupported OS $OS_NAME $OS_VER"
-  $ECHO "Exiting..."
-  exit 1
- fi
-}
-
-checkconf ()
-{
-# Check endlessh config file
- config=$1
- if [ -f "$ENDLESSH_CONF_PATH"/"$config" ]; then
-  $ECHO "1"
- else
-  $ECHO "0"
- fi  
-}
-
-startproc() 
-{
-# Start endlessh daemon
- program=$1
- if [ "`checkconf $ENDLESSH_CONF_FILE`" != "1" ]; then
-  $ECHO "ERROR: Config file $ENDLESSH_CONF_PATH/$ENDLESSH_CONF_FILE not found."  
-  $ECHO "Exiting..."
-  exit 2
- else
-  $ENDLESSH_PATH/$program -f $ENDLESSH_CONF_PATH/$ENDLESSH_CONF_FILE -v >$LOGFILE &
- fi
-}
-
-stopproc() 
-{
-# Stop endlessh daemon
- program=$1
- if [ "`checkconf $ENDLESSH_CONF_FILE`" != "1" ]; then
-  $ECHO "ERROR: Config file $ENDLESSH_CONF_PATH/$ENDLESSH_CONF_FILE not found."  
-  $ECHO "Exiting..."
-  exit 2
- else
-  $KILL -s TERM `$PGREP $program`>/dev/null 2>&1
- fi
-}
-
-##############
-# Main block #
-##############
-
-# Check endlessh installed
-check_endlessh $ENDLESSH_BIN_FILE
-
-# Check OS version
-check_os
-
-case "$1" in
-"start")
-  startproc $ENDLESSH_BIN_FILE
-  ;;
-"stop")
-  stopproc $ENDLESSH_BIN_FILE
-  ;;
-"refresh")
-  $KILL -s HUP `$PGREP $ENDLESSH_BIN_FILE`>/dev/null 2>&1
-  ;;
-"restart")
-  stopproc $ENDLESSH_BIN_FILE
-  startproc $ENDLESSH_BIN_FILE
-  ;;
-*)
-  $ECHO "Usage: $0 { start | stop | restart | refresh }"
-  exit 1
-esac
-
-exit 0