- (djm) Rework ssh-rand-helper:

   - Reduce quantity of ifdef code, in preparation for ssh_rand_conf
   - Always seed from system calls, even when doing PRNGd seeding
   - Tidy and comment #define knobs
   - Remove unused facility for multiple runs through command list
   - KNF, cleanup, update copyright

2 files changed, 358 insertions, 349 deletions

diff --git a/ChangeLog b/ChangeLog
index 70e50f786..731337317 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+20020121
+ - (djm) Rework ssh-rand-helper:
+   - Reduce quantity of ifdef code, in preparation for ssh_rand_conf
+   - Always seed from system calls, even when doing PRNGd seeding
+   - Tidy and comment #define knobs
+   - Remove unused facility for multiple runs through command list
+   - KNF, cleanup, update copyright
+
 20020114
  - (djm) Bug #50 - make autoconf entropy path checks more robust
 
@@ -7136,4 +7144,4 @@
  - Wrote replacements for strlcpy and mkdtemp
  - Released 1.0pre1
 
-$Id: ChangeLog,v 1.1720 2002/01/14 08:01:03 djm Exp $
+$Id: ChangeLog,v 1.1721 2002/01/21 12:44:12 djm Exp $
diff --git a/ssh-rand-helper.c b/ssh-rand-helper.c
index 380fee46d..596622b42 100644
--- a/ssh-rand-helper.c
+++ b/ssh-rand-helper.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001 Damien Miller.  All rights reserved.
+ * Copyright (c) 2001-2002 Damien Miller.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -39,37 +39,41 @@
 #include "pathnames.h"
 #include "log.h"
 
-#ifdef HAVE___PROGNAME
-extern char *__progname;
-#else
-char *__progname;
-#endif
+RCSID("$Id: ssh-rand-helper.c,v 1.3 2002/01/21 12:44:12 djm Exp $");
 
-RCSID("$Id: ssh-rand-helper.c,v 1.2 2001/12/25 04:32:58 stevesk Exp $");
+/* Number of bytes we write out */
+#define OUTPUT_SEED_SIZE        48
 
-#define RANDOM_SEED_SIZE 48
+/* Length of on-disk seedfiles */
+#define SEED_FILE_SIZE          1024
 
+/* Maximum number of command-line arguments to read from file */
+#define NUM_ARGS                10
+
+/* Minimum number of usable commands to be considered sufficient */
+#define MIN_ENTROPY_SOURCES     16
+
+/* Path to on-disk seed file (relative to user's home directory */
 #ifndef SSH_PRNG_SEED_FILE
 # define SSH_PRNG_SEED_FILE      _PATH_SSH_USER_DIR"/prng_seed"
-#endif /* SSH_PRNG_SEED_FILE */
+#endif
+
+/* Path to PRNG commands list */
 #ifndef SSH_PRNG_COMMAND_FILE
 # define SSH_PRNG_COMMAND_FILE   ETCDIR "/ssh_prng_cmds"
-#endif /* SSH_PRNG_COMMAND_FILE */
+#endif
+
 
+#ifdef HAVE___PROGNAME
+extern char *__progname;
+#else
+char *__progname;
+#endif
 
 #ifndef offsetof
 # define offsetof(type, member) ((size_t) &((type *)0)->member)
 #endif
 
-/* Number of times to pass through command list gathering entropy */
-#define NUM_ENTROPY_RUNS        1
-
-/* Scale entropy estimates back by this amount on subsequent runs */
-#define SCALE_PER_RUN           10.0
-
-/* Minimum number of commands to be considered valid */
-#define MIN_ENTROPY_SOURCES 16
-
 #define WHITESPACE " \t\n"
 
 #ifndef RUSAGE_SELF
@@ -81,70 +85,104 @@ RCSID("$Id: ssh-rand-helper.c,v 1.2 2001/12/25 04:32:58 stevesk Exp $");
 
 #if defined(PRNGD_SOCKET) || defined(PRNGD_PORT)
 # define USE_PRNGD
+#else
+# define USE_SEED_FILES
 #endif
 
-#ifdef USE_PRNGD
-/* Collect entropy from PRNGD/EGD */
+typedef struct {
+        /* Proportion of data that is entropy */
+        double rate;
+        /* Counter goes positive if this command times out */
+        unsigned int badness;
+        /* Increases by factor of two each timeout */
+        unsigned int sticky_badness;
+        /* Path to executable */
+        char *path;
+        /* argv to pass to executable */
+        char *args[NUM_ARGS]; /* XXX: arbitrary limit */
+        /* full command string (debug) */
+        char *cmdstring;
+} entropy_cmd_t;
+
+/* slow command timeouts (all in milliseconds) */
+/* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */
+static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC;
+
+/* this is initialised from a file, by prng_read_commands() */
+static entropy_cmd_t *entropy_cmds = NULL;
+
+/* Prototypes */
+double stir_from_system(void);
+double stir_from_programs(void);
+double stir_gettimeofday(double entropy_estimate);
+double stir_clock(double entropy_estimate);
+double stir_rusage(int who, double entropy_estimate);
+double hash_command_output(entropy_cmd_t *src, char *hash);
+int get_random_bytes_prngd(unsigned char *buf, int len, 
+    unsigned short tcp_port, char *socket_path);
+
+/*
+ * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon
+ * listening either on 'tcp_port', or via Unix domain socket at *
+ * 'socket_path'.
+ * Either a non-zero tcp_port or a non-null socket_path must be 
+ * supplied.
+ * Returns 0 on success, -1 on error
+ */
 int
-get_random_bytes(unsigned char *buf, int len)
+get_random_bytes_prngd(unsigned char *buf, int len, 
+    unsigned short tcp_port, char *socket_path)
 {
-        int fd;
+        int fd, addr_len, rval, errors;
         char msg[2];
-#ifdef PRNGD_PORT
-        struct sockaddr_in addr;
-#else
-        struct sockaddr_un addr;
-#endif
-        int addr_len, rval, errors;
+        struct sockaddr_storage addr;
+        struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr;
+        struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr;
         mysig_t old_sigpipe;
 
+        /* Sanity checks */
+        if (socket_path == NULL && tcp_port == 0)
+                fatal("You must specify a port or a socket");
+        if (socket_path != NULL &&
+            strlen(socket_path) >= sizeof(addr_un->sun_path))
+                fatal("Random pool path is too long");
         if (len > 255)
                 fatal("Too many bytes to read from PRNGD");
 
         memset(&addr, '\0', sizeof(addr));
 
-#ifdef PRNGD_PORT
-        addr.sin_family = AF_INET;
-        addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
-        addr.sin_port = htons(PRNGD_PORT);
-        addr_len = sizeof(struct sockaddr_in);
-#else /* use IP socket PRNGD_SOCKET instead */
-        /* Sanity checks */
-        if (sizeof(PRNGD_SOCKET) > sizeof(addr.sun_path))
-                fatal("Random pool path is too long");
-
-        addr.sun_family = AF_UNIX;
-        strlcpy(addr.sun_path, PRNGD_SOCKET, sizeof(addr.sun_path));
-        addr_len = offsetof(struct sockaddr_un, sun_path) +
-            sizeof(PRNGD_SOCKET);
-#endif
+        if (tcp_port != 0) {
+                addr_in->sin_family = AF_INET;
+                addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+                addr_in->sin_port = htons(tcp_port);
+                addr_len = sizeof(*addr_in);
+        } else {
+                addr_un->sun_family = AF_UNIX;
+                strlcpy(addr_un->sun_path, socket_path,
+                    sizeof(addr_un->sun_path));
+                addr_len = offsetof(struct sockaddr_un, sun_path) +
+                    strlen(socket_path) + 1;
+        }
 
         old_sigpipe = mysignal(SIGPIPE, SIG_IGN);
 
-        errors = rval = 0;
+        errors = 0;
+        rval = -1;
 reopen:
-#ifdef PRNGD_PORT
-        fd = socket(addr.sin_family, SOCK_STREAM, 0);
-        if (fd == -1) {
-                error("Couldn't create AF_INET socket: %s", strerror(errno));
-                goto done;
-        }
-#else
-        fd = socket(addr.sun_family, SOCK_STREAM, 0);
+        fd = socket(addr.ss_family, SOCK_STREAM, 0);
         if (fd == -1) {
-                error("Couldn't create AF_UNIX socket: %s", strerror(errno));
+                error("Couldn't create socket: %s", strerror(errno));
                 goto done;
         }
-#endif
 
         if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) {
-#ifdef PRNGD_PORT
-                error("Couldn't connect to PRNGD port %d: %s",
-                    PRNGD_PORT, strerror(errno));
-#else
-                error("Couldn't connect to PRNGD socket \"%s\": %s",
-                    addr.sun_path, strerror(errno));
-#endif
+                if (tcp_port != 0) {
+                        error("Couldn't connect to PRNGD port %d: %s",
+                            tcp_port, strerror(errno));
+                } else {
+                        error("Couldn't connect to PRNGD socket \"%s\": %s",
+                            addr_un->sun_path, strerror(errno));
+                }
                 goto done;
         }
 
@@ -174,146 +212,12 @@ reopen:
                 goto done;
         }
 
-        rval = 1;
+        rval = 0;
 done:
         mysignal(SIGPIPE, old_sigpipe);
         if (fd != -1)
                 close(fd);
-        return(rval);
-}
-
-static void
-seed_openssl_rng(void)
-{
-        unsigned char buf[RANDOM_SEED_SIZE];
-
-        if (!get_random_bytes(buf, sizeof(buf)))
-                fatal("Entropy collection failed");
-
-        RAND_add(buf, sizeof(buf), sizeof(buf));
-        memset(buf, '\0', sizeof(buf));
-}
-
-#else /* USE_PRNGD */
-
-/*
- * FIXME: proper entropy estimations. All current values are guesses
- * FIXME: (ATL) do estimates at compile time?
- * FIXME: More entropy sources
- */
-
-/* slow command timeouts (all in milliseconds) */
-/* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */
-static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC;
-
-typedef struct
-{
-        /* Proportion of data that is entropy */
-        double rate;
-        /* Counter goes positive if this command times out */
-        unsigned int badness;
-        /* Increases by factor of two each timeout */
-        unsigned int sticky_badness;
-        /* Path to executable */
-        char *path;
-        /* argv to pass to executable */
-        char *args[5];
-        /* full command string (debug) */
-        char *cmdstring;
-} entropy_source_t;
-
-double stir_from_system(void);
-double stir_from_programs(void);
-double stir_gettimeofday(double entropy_estimate);
-double stir_clock(double entropy_estimate);
-double stir_rusage(int who, double entropy_estimate);
-double hash_output_from_command(entropy_source_t *src, char *hash);
-
-/* this is initialised from a file, by prng_read_commands() */
-entropy_source_t *entropy_sources = NULL;
-
-double
-stir_from_system(void)
-{
-        double total_entropy_estimate;
-        long int i;
-
-        total_entropy_estimate = 0;
-
-        i = getpid();
-        RAND_add(&i, sizeof(i), 0.5);
-        total_entropy_estimate += 0.1;
-
-        i = getppid();
-        RAND_add(&i, sizeof(i), 0.5);
-        total_entropy_estimate += 0.1;
-
-        i = getuid();
-        RAND_add(&i, sizeof(i), 0.0);
-        i = getgid();
-        RAND_add(&i, sizeof(i), 0.0);
-
-        total_entropy_estimate += stir_gettimeofday(1.0);
-        total_entropy_estimate += stir_clock(0.5);
-        total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0);
-
-        return(total_entropy_estimate);
-}
-
-double
-stir_from_programs(void)
-{
-        int i;
-        int c;
-        double entropy_estimate;
-        double total_entropy_estimate;
-        char hash[SHA_DIGEST_LENGTH];
-
-        total_entropy_estimate = 0;
-        for(i = 0; i < NUM_ENTROPY_RUNS; i++) {
-                c = 0;
-                while (entropy_sources[c].path != NULL) {
-
-                        if (!entropy_sources[c].badness) {
-                                /* Hash output from command */
-                                entropy_estimate = hash_output_from_command(&entropy_sources[c], hash);
-
-                                /* Scale back entropy estimate according to command's rate */
-                                entropy_estimate *= entropy_sources[c].rate;
-
-                                /* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */
-                                if (entropy_estimate > SHA_DIGEST_LENGTH)
-                                        entropy_estimate = SHA_DIGEST_LENGTH;
-
-                                /* Scale back estimates for subsequent passes through list */
-                                entropy_estimate /= SCALE_PER_RUN * (i + 1.0);
-
-                                /* Stir it in */
-                                RAND_add(hash, sizeof(hash), entropy_estimate);
-
-                                debug3("Got %0.2f bytes of entropy from '%s'", entropy_estimate,
-                                        entropy_sources[c].cmdstring);
-
-                                total_entropy_estimate += entropy_estimate;
-
-                        /* Execution times should be a little unpredictable */
-                                total_entropy_estimate += stir_gettimeofday(0.05);
-                                total_entropy_estimate += stir_clock(0.05);
-                                total_entropy_estimate += stir_rusage(RUSAGE_SELF, 0.1);
-                                total_entropy_estimate += stir_rusage(RUSAGE_CHILDREN, 0.1);
-                        } else {
-                                debug2("Command '%s' disabled (badness %d)",
-                                        entropy_sources[c].cmdstring, entropy_sources[c].badness);
-
-                                if (entropy_sources[c].badness > 0)
-                                        entropy_sources[c].badness--;
-                        }
-
-                        c++;
-                }
-        }
-
-        return(total_entropy_estimate);
+        return rval;
 }
 
 double
@@ -326,7 +230,7 @@ stir_gettimeofday(double entropy_estimate)
 
         RAND_add(&tv, sizeof(tv), entropy_estimate);
 
-        return(entropy_estimate);
+        return entropy_estimate;
 }
 
 double
@@ -338,9 +242,9 @@ stir_clock(double entropy_estimate)
         c = clock();
         RAND_add(&c, sizeof(c), entropy_estimate);
 
-        return(entropy_estimate);
+        return entropy_estimate;
 #else /* _HAVE_CLOCK */
-        return(0);
+        return 0;
 #endif /* _HAVE_CLOCK */
 }
 
@@ -351,19 +255,19 @@ stir_rusage(int who, double entropy_estimate)
         struct rusage ru;
 
         if (getrusage(who, &ru) == -1)
-                return(0);
+                return 0;
 
         RAND_add(&ru, sizeof(ru), entropy_estimate);
 
-        return(entropy_estimate);
+        return entropy_estimate;
 #else /* _HAVE_GETRUSAGE */
-        return(0);
+        return 0;
 #endif /* _HAVE_GETRUSAGE */
 }
 
-
 static int
-_get_timeval_msec_difference(struct timeval *t1, struct timeval *t2) {
+timeval_diff(struct timeval *t1, struct timeval *t2)
+{
         int secdiff, usecdiff;
 
         secdiff = t2->tv_sec - t1->tv_sec;
@@ -372,27 +276,24 @@ _get_timeval_msec_difference(struct timeval *t1, struct timeval *t2) {
 }
 
 double
-hash_output_from_command(entropy_source_t *src, char *hash)
+hash_command_output(entropy_cmd_t *src, char *hash)
 {
-        static int devnull = -1;
-        int p[2];
+        char buf[8192];
         fd_set rdset;
-        int cmd_eof = 0, error_abort = 0;
-        struct timeval tv_start, tv_current;
-        int msec_elapsed = 0;
+        int bytes_read, cmd_eof, error_abort, msec_elapsed, p[2];
+        int status, total_bytes_read;
+        static int devnull = -1;
         pid_t pid;
-        int status;
-        char buf[16384];
-        int bytes_read;
-        int total_bytes_read;
         SHA_CTX sha;
+        struct timeval tv_start, tv_current;
 
         debug3("Reading output from \'%s\'", src->cmdstring);
 
         if (devnull == -1) {
                 devnull = open("/dev/null", O_RDWR);
                 if (devnull == -1)
-                        fatal("Couldn't open /dev/null: %s", strerror(errno));
+                        fatal("Couldn't open /dev/null: %s", 
+                            strerror(errno));
         }
 
         if (pipe(p) == -1)
@@ -415,8 +316,9 @@ hash_output_from_command(entropy_source_t *src, char *hash)
                         close(devnull);
 
                         execv(src->path, (char**)(src->args));
-                        debug("(child) Couldn't exec '%s': %s", src->cmdstring,
-                              strerror(errno));
+
+                        debug("(child) Couldn't exec '%s': %s", 
+                            src->cmdstring, strerror(errno));
                         _exit(-1);
                 default: /* Parent */
                         break;
@@ -428,15 +330,15 @@ hash_output_from_command(entropy_source_t *src, char *hash)
 
         /* Hash output from child */
         SHA1_Init(&sha);
-        total_bytes_read = 0;
 
+        cmd_eof = error_abort = msec_elapsed = total_bytes_read = 0;
         while (!error_abort && !cmd_eof) {
                 int ret;
                 struct timeval tv;
                 int msec_remaining;
 
                 (void) gettimeofday(&tv_current, 0);
-                msec_elapsed = _get_timeval_msec_difference(&tv_start, &tv_current);
+                msec_elapsed = timeval_diff(&tv_start, &tv_current);
                 if (msec_elapsed >= entropy_timeout_current) {
                         error_abort=1;
                         continue;
@@ -445,10 +347,10 @@ hash_output_from_command(entropy_source_t *src, char *hash)
 
                 FD_ZERO(&rdset);
                 FD_SET(p[0], &rdset);
-                tv.tv_sec =  msec_remaining / 1000;
+                tv.tv_sec = msec_remaining / 1000;
                 tv.tv_usec = (msec_remaining % 1000) * 1000;
 
-                ret = select(p[0]+1, &rdset, NULL, NULL, &tv);
+                ret = select(p[0] + 1, &rdset, NULL, NULL, &tv);
 
                 RAND_add(&tv, sizeof(tv), 0.0);
 
@@ -476,8 +378,8 @@ hash_output_from_command(entropy_source_t *src, char *hash)
                 case -1:
                 default:
                         /* error */
-                        debug("Command '%s': select() failed: %s", src->cmdstring,
-                              strerror(errno));
+                        debug("Command '%s': select() failed: %s", 
+                            src->cmdstring, strerror(errno));
                         error_abort = 1;
                         break;
                 }
@@ -490,93 +392,174 @@ hash_output_from_command(entropy_source_t *src, char *hash)
         debug3("Time elapsed: %d msec", msec_elapsed);
 
         if (waitpid(pid, &status, 0) == -1) {
-               error("Couldn't wait for child '%s' completion: %s", src->cmdstring,
-                     strerror(errno));
-                return(0.0);
+               error("Couldn't wait for child '%s' completion: %s",
+                   src->cmdstring, strerror(errno));
+                return 0.0;
         }
 
         RAND_add(&status, sizeof(&status), 0.0);
 
         if (error_abort) {
-                /* closing p[0] on timeout causes the entropy command to
-                 * SIGPIPE. Take whatever output we got, and mark this command
-                 * as slow */
+                /*
+                 * Closing p[0] on timeout causes the entropy command to
+                 * SIGPIPE. Take whatever output we got, and mark this 
+                 * command as slow 
+                 */
                 debug2("Command '%s' timed out", src->cmdstring);
                 src->sticky_badness *= 2;
                 src->badness = src->sticky_badness;
-                return(total_bytes_read);
+                return total_bytes_read;
         }
 
         if (WIFEXITED(status)) {
-                if (WEXITSTATUS(status)==0) {
-                        return(total_bytes_read);
+                if (WEXITSTATUS(status) == 0) {
+                        return total_bytes_read;
                 } else {
-                        debug2("Command '%s' exit status was %d", src->cmdstring,
-                                WEXITSTATUS(status));
+                        debug2("Command '%s' exit status was %d",
+                            src->cmdstring, WEXITSTATUS(status));
                         src->badness = src->sticky_badness = 128;
-                        return (0.0);
+                        return 0.0;
                 }
         } else if (WIFSIGNALED(status)) {
-                debug2("Command '%s' returned on uncaught signal %d !", src->cmdstring,
-                        status);
+                debug2("Command '%s' returned on uncaught signal %d !",
+                    src->cmdstring, status);
                 src->badness = src->sticky_badness = 128;
-                return(0.0);
+                return 0.0;
         } else
-                return(0.0);
+                return 0.0;
+}
+
+double
+stir_from_system(void)
+{
+        double total_entropy_estimate;
+        long int i;
+
+        total_entropy_estimate = 0;
+
+        i = getpid();
+        RAND_add(&i, sizeof(i), 0.5);
+        total_entropy_estimate += 0.1;
+
+        i = getppid();
+        RAND_add(&i, sizeof(i), 0.5);
+        total_entropy_estimate += 0.1;
+
+        i = getuid();
+        RAND_add(&i, sizeof(i), 0.0);
+        i = getgid();
+        RAND_add(&i, sizeof(i), 0.0);
+
+        total_entropy_estimate += stir_gettimeofday(1.0);
+        total_entropy_estimate += stir_clock(0.5);
+        total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0);
+
+        return total_entropy_estimate;
+}
+
+double
+stir_from_programs(void)
+{
+        int c;
+        double entropy, total_entropy;
+        char hash[SHA_DIGEST_LENGTH];
+
+        total_entropy = 0;
+        for(c = 0; entropy_cmds[c].path != NULL; c++) {
+                if (!entropy_cmds[c].badness) {
+                        /* Hash output from command */
+                        entropy = hash_command_output(&entropy_cmds[c],
+                            hash);
+
+                        /* Scale back estimate by command's rate */
+                        entropy *= entropy_cmds[c].rate;
+
+                        /* Upper bound of entropy is SHA_DIGEST_LENGTH */
+                        if (entropy > SHA_DIGEST_LENGTH)
+                                entropy = SHA_DIGEST_LENGTH;
+
+                        /* Stir it in */
+                        RAND_add(hash, sizeof(hash), entropy);
+
+                        debug3("Got %0.2f bytes of entropy from '%s'", 
+                            entropy, entropy_cmds[c].cmdstring);
+
+                        total_entropy += entropy;
+
+                        /* Execution time should be a bit unpredictable */
+                        total_entropy += stir_gettimeofday(0.05);
+                        total_entropy += stir_clock(0.05);
+                        total_entropy += stir_rusage(RUSAGE_SELF, 0.1);
+                        total_entropy += stir_rusage(RUSAGE_CHILDREN, 0.1);
+                } else {
+                        debug2("Command '%s' disabled (badness %d)",
+                            entropy_cmds[c].cmdstring, 
+                            entropy_cmds[c].badness);
+
+                        if (entropy_cmds[c].badness > 0)
+                                entropy_cmds[c].badness--;
+                }
+        }
+
+        return total_entropy;
 }
 
 /*
  * prng seedfile functions
  */
 int
-prng_check_seedfile(char *filename) {
-
+prng_check_seedfile(char *filename)
+{
         struct stat st;
 
-        /* FIXME raceable: eg replace seed between this stat and subsequent open */
-        /* Not such a problem because we don't trust the seed file anyway */
+        /*
+         * XXX raceable: eg replace seed between this stat and subsequent 
+         * open. Not such a problem because we don't really trust the 
+         * seed file anyway.
+         * XXX: use secure path checking as elsewhere in OpenSSH
+         */
         if (lstat(filename, &st) == -1) {
                 /* Give up on hard errors */
                 if (errno != ENOENT)
-                        debug("WARNING: Couldn't stat random seed file \"%s\": %s",
-                           filename, strerror(errno));
-
-                return(0);
+                        debug("WARNING: Couldn't stat random seed file "
+                            "\"%.100s\": %s", filename, strerror(errno));
+                return 0;
         }
 
         /* regular file? */
         if (!S_ISREG(st.st_mode))
-                fatal("PRNG seedfile %.100s is not a regular file", filename);
+                fatal("PRNG seedfile %.100s is not a regular file",
+                    filename);
 
         /* mode 0600, owned by root or the current user? */
         if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid())) {
-                debug("WARNING: PRNG seedfile %.100s must be mode 0600, owned by uid %d",
-                         filename, getuid());
-                return(0);
+                debug("WARNING: PRNG seedfile %.100s must be mode 0600, "
+                    "owned by uid %d", filename, getuid());
+                return 0;
         }
 
-        return(1);
+        return 1;
 }
 
 void
-prng_write_seedfile(void) {
+prng_write_seedfile(void)
+{
         int fd;
-        char seed[1024];
-        char filename[1024];
+        char seed[SEED_FILE_SIZE], filename[MAXPATHLEN];
         struct passwd *pw;
 
         pw = getpwuid(getuid());
         if (pw == NULL)
-                fatal("Couldn't get password entry for current user (%i): %s",
-                        getuid(), strerror(errno));
+                fatal("Couldn't get password entry for current user "
+                    "(%i): %s", getuid(), strerror(errno));
 
         /* Try to ensure that the parent directory is there */
         snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
-                _PATH_SSH_USER_DIR);
+            _PATH_SSH_USER_DIR);
         mkdir(filename, 0700);
 
         snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
-                SSH_PRNG_SEED_FILE);
+            SSH_PRNG_SEED_FILE);
 
         debug("writing PRNG seed to file %.100s", filename);
 
@@ -586,27 +569,27 @@ prng_write_seedfile(void) {
         prng_check_seedfile(filename);
 
         if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) {
-                debug("WARNING: couldn't access PRNG seedfile %.100s (%.100s)",
-                   filename, strerror(errno));
+                debug("WARNING: couldn't access PRNG seedfile %.100s "
+                    "(%.100s)", filename, strerror(errno));
         } else {
-                if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed))
-                        fatal("problem writing PRNG seedfile %.100s (%.100s)", filename,
-                                 strerror(errno));
+                if (atomicio(write, fd, &seed, sizeof(seed)) < sizeof(seed))
+                        fatal("problem writing PRNG seedfile %.100s "
+                            "(%.100s)", filename, strerror(errno));
                 close(fd);
         }
 }
 
 void
-prng_read_seedfile(void) {
+prng_read_seedfile(void)
+{
         int fd;
-        char seed[1024];
-        char filename[1024];
+        char seed[SEED_FILE_SIZE], filename[MAXPATHLEN];
         struct passwd *pw;
 
         pw = getpwuid(getuid());
         if (pw == NULL)
-                fatal("Couldn't get password entry for current user (%i): %s",
-                        getuid(), strerror(errno));
+                fatal("Couldn't get password entry for current user "
+                    "(%i): %s", getuid(), strerror(errno));
 
         snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
                 SSH_PRNG_SEED_FILE);
@@ -614,19 +597,19 @@ prng_read_seedfile(void) {
         debug("loading PRNG seed from file %.100s", filename);
 
         if (!prng_check_seedfile(filename)) {
-                verbose("Random seed file not found or not valid, ignoring.");
+                verbose("Random seed file not found or invalid, ignoring.");
                 return;
         }
 
         /* open the file and read in the seed */
         fd = open(filename, O_RDONLY);
         if (fd == -1)
-                fatal("could not open PRNG seedfile %.100s (%.100s)", filename,
-                        strerror(errno));
+                fatal("could not open PRNG seedfile %.100s (%.100s)",
+                    filename, strerror(errno));
 
-        if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) {
-                verbose("invalid or short read from PRNG seedfile %.100s - ignoring",
-                        filename);
+        if (atomicio(read, fd, &seed, sizeof(seed)) < sizeof(seed)) {
+                verbose("invalid or short read from PRNG seedfile "
+                    "%.100s - ignoring", filename);
                 memset(seed, '\0', sizeof(seed));
         }
         close(fd);
@@ -642,81 +625,78 @@ prng_read_seedfile(void) {
 int
 prng_read_commands(char *cmdfilename)
 {
-        FILE *f;
-        char *cp;
-        char line[1024];
-        char cmd[1024];
-        char path[256];
-        int linenum;
-        int num_cmds = 64;
-        int cur_cmd = 0;
+        char cmd[SEED_FILE_SIZE], *cp, line[1024], path[SEED_FILE_SIZE];
         double est;
-        entropy_source_t *entcmd;
+        entropy_cmd_t *entcmd;
+        FILE *f;
+        int cur_cmd, linenum, num_cmds, arg;
 
-        f = fopen(cmdfilename, "r");
-        if (!f) {
+        if ((f = fopen(cmdfilename, "r")) == NULL) {
                 fatal("couldn't read entropy commands file %.100s: %.100s",
                     cmdfilename, strerror(errno));
         }
 
-        entcmd = (entropy_source_t *)xmalloc(num_cmds * sizeof(entropy_source_t));
-        memset(entcmd, '\0', num_cmds * sizeof(entropy_source_t));
+        num_cmds = 64;
+        entcmd = xmalloc(num_cmds * sizeof(entropy_cmd_t));
+        memset(entcmd, '\0', num_cmds * sizeof(entropy_cmd_t));
 
         /* Read in file */
-        linenum = 0;
+        cur_cmd = linenum = 0;
         while (fgets(line, sizeof(line), f)) {
-                int arg;
-                char *argv;
-
                 linenum++;
 
-                /* skip leading whitespace, test for blank line or comment */
+                /* Skip leading whitespace, blank lines and comments */
                 cp = line + strspn(line, WHITESPACE);
                 if ((*cp == 0) || (*cp == '#'))
                         continue; /* done with this line */
 
-                /* First non-whitespace char should be double quote delimiting */
-                /* commandline */
+                /*
+                 * The first non-whitespace char should be a double quote 
+                 * delimiting the commandline
+                 */
                 if (*cp != '"') {
-                        error("bad entropy command, %.100s line %d", cmdfilename,
-                             linenum);
+                        error("bad entropy command, %.100s line %d",
+                            cmdfilename, linenum);
                         continue;
                 }
 
-                /* first token, command args (incl. argv[0]) in double quotes */
+                /*
+                 * First token, command args (incl. argv[0]) in double
+                 * quotes
+                 */
                 cp = strtok(cp, "\"");
                 if (cp == NULL) {
-                        error("missing or bad command string, %.100s line %d -- ignored",
-                              cmdfilename, linenum);
+                        error("missing or bad command string, %.100s "
+                            "line %d -- ignored", cmdfilename, linenum);
                         continue;
                 }
                 strlcpy(cmd, cp, sizeof(cmd));
 
-                /* second token, full command path */
+                /* Second token, full command path */
                 if ((cp = strtok(NULL, WHITESPACE)) == NULL) {
-                        error("missing command path, %.100s line %d -- ignored",
-                              cmdfilename, linenum);
+                        error("missing command path, %.100s "
+                            "line %d -- ignored", cmdfilename, linenum);
                         continue;
                 }
 
-                /* did configure mark this as dead? */
+                /* Did configure mark this as dead? */
                 if (strncmp("undef", cp, 5) == 0)
                         continue;
 
                 strlcpy(path, cp, sizeof(path));
 
-                /* third token, entropy rate estimate for this command */
+                /* Third token, entropy rate estimate for this command */
                 if ((cp = strtok(NULL, WHITESPACE)) == NULL) {
-                        error("missing entropy estimate, %.100s line %d -- ignored",
-                              cmdfilename, linenum);
+                        error("missing entropy estimate, %.100s "
+                            "line %d -- ignored", cmdfilename, linenum);
                         continue;
                 }
-                est = strtod(cp, &argv);
+                est = strtod(cp, NULL);
 
                 /* end of line */
                 if ((cp = strtok(NULL, WHITESPACE)) != NULL) {
-                        error("garbage at end of line %d in %.100s -- ignored", linenum,
-                                cmdfilename);
+                        error("garbage at end of line %d in %.100s "
+                            "-- ignored", linenum, cmdfilename);
                         continue;
                 }
 
@@ -726,17 +706,14 @@ prng_read_commands(char *cmdfilename)
                 /* split the command args */
                 cp = strtok(cmd, WHITESPACE);
                 arg = 0;
-                argv = NULL;
                 do {
-                        char *s = (char*)xmalloc(strlen(cp) + 1);
-                        strncpy(s, cp, strlen(cp) + 1);
-                        entcmd[cur_cmd].args[arg] = s;
+                        entcmd[cur_cmd].args[arg] = xstrdup(cp);
                         arg++;
-                } while ((arg < 5) && (cp = strtok(NULL, WHITESPACE)));
+                } while(arg < NUM_ARGS && (cp = strtok(NULL, WHITESPACE)));
 
                 if (strtok(NULL, WHITESPACE))
-                        error("ignored extra command elements (max 5), %.100s line %d",
-                              cmdfilename, linenum);
+                        error("ignored extra commands (max %d), %.100s "
+                            "line %d", NUM_ARGS, cmdfilename, linenum);
 
                 /* Copy the command path and rate estimate */
                 entcmd[cur_cmd].path = xstrdup(path);
@@ -747,56 +724,80 @@ prng_read_commands(char *cmdfilename)
 
                 cur_cmd++;
 
-                /* If we've filled the array, reallocate it twice the size */
-                /* Do this now because even if this we're on the last command,
-                   we need another slot to mark the last entry */
+                /*
+                 * If we've filled the array, reallocate it twice the size
+                 * Do this now because even if this we're on the last 
+                 * command we need another slot to mark the last entry
+                 */
                 if (cur_cmd == num_cmds) {
                         num_cmds *= 2;
-                        entcmd = xrealloc(entcmd, num_cmds * sizeof(entropy_source_t));
+                        entcmd = xrealloc(entcmd, num_cmds *
+                            sizeof(entropy_cmd_t));
                 }
         }
 
         /* zero the last entry */
-        memset(&entcmd[cur_cmd], '\0', sizeof(entropy_source_t));
+        memset(&entcmd[cur_cmd], '\0', sizeof(entropy_cmd_t));
 
         /* trim to size */
-        entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t));
-
-        debug("Loaded %d entropy commands from %.100s", cur_cmd, cmdfilename);
-
-        return (cur_cmd >= MIN_ENTROPY_SOURCES);
-}
-
-static void
-seed_openssl_rng(void)
-{
-        /* Read in collection commands */
-        if (!prng_read_commands(SSH_PRNG_COMMAND_FILE))
-                fatal("PRNG initialisation failed -- exiting.");
-
-        prng_read_seedfile();
+        entropy_cmds = xrealloc(entcmd, (cur_cmd + 1) *
+            sizeof(entropy_cmd_t));
 
-        debug("Seeded RNG with %i bytes from programs", 
-            (int)stir_from_programs());
-        debug("Seeded RNG with %i bytes from system calls", 
-            (int)stir_from_system());
+        debug("Loaded %d entropy commands from %.100s", cur_cmd,
+            cmdfilename);
 
-        prng_write_seedfile();
+        return cur_cmd < MIN_ENTROPY_SOURCES ? -1 : 0;
 }
 
-#endif /* USE_PRNGD */
-
 int 
 main(int argc, char **argv)
 {
-        unsigned char buf[48];
+        unsigned char buf[OUTPUT_SEED_SIZE];
         int ret;
 
         __progname = get_progname(argv[0]);
         /* XXX: need some debugging mode */
         log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1);
 
-        seed_openssl_rng();
+#ifdef USE_SEED_FILES
+        prng_read_seedfile();
+#endif
+
+        /*
+         * Seed the RNG from wherever we can
+         */
+         
+        /* Take whatever is on the stack, but don't credit it */
+        RAND_add(buf, sizeof(buf), 0);
+
+        debug("Seeded RNG with %i bytes from system calls", 
+            (int)stir_from_system());
+
+#ifdef PRNGD_PORT
+        if (get_random_bytes_prngd(buf, sizeof(buf), PRNGD_PORT,
+            NULL) == -1)
+                fatal("Entropy collection failed");
+        RAND_add(buf, sizeof(buf), sizeof(buf));
+#elif PRNGD_SOCKET
+        if (get_random_bytes_prngd(buf, sizeof(buf), PRNGD_SOCKET,
+            NULL) == -1)
+                fatal("Entropy collection failed");
+        RAND_add(buf, sizeof(buf), sizeof(buf));
+#else
+        /* Read in collection commands */
+        if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1)
+                fatal("PRNG initialisation failed -- exiting.");
+        debug("Seeded RNG with %i bytes from programs", 
+            (int)stir_from_programs());
+#endif
+
+#ifdef USE_SEED_FILES
+        prng_write_seedfile();
+#endif
+
+        /*
+         * Write the seed to stdout
+         */
 
         if (!RAND_status())
                 fatal("Not enough entropy in RNG");