X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=client_common.c;h=f0efe42fd49769db17d341f1d325b72661e4918d;hp=197f031c476a79ee00bc2143945356a20330595c;hb=6d5159ed6235647bca461a9414543f76eb0b6da6;hpb=a5927501e41fa3fca2975452617474e78ffecc48

diff --git a/client_common.c b/client_common.c
index 197f031c..f0efe42f 100644
--- a/client_common.c
+++ b/client_common.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1997-2009 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 1997-2013 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -8,44 +8,67 @@
 
 #include <regex.h>
 #include <sys/types.h>
-#include <dirent.h>
-#include <openssl/rc4.h>
 
 #include "para.h"
 #include "error.h"
 #include "list.h"
 #include "sched.h"
-#include "client.cmdline.h"
 #include "crypt.h"
-#include "rc4.h"
 #include "net.h"
 #include "fd.h"
+#include "sideband.h"
 #include "string.h"
 #include "client.cmdline.h"
 #include "client.h"
-#include "hash.h"
 #include "buffer_tree.h"
+#include "version.h"
 
 /** The size of the receiving buffer. */
 #define CLIENT_BUFSIZE 4000
 
+/**
+ * Close the connection to para_server and deallocate per-command ressources.
+ *
+ * \param ct The client task.
+ *
+ * This frees all ressources of the current command but keeps the configuration
+ * in \p ct->conf.
+ *
+ * \sa \ref client_close().
+ */
+void client_disconnect(struct client_task *ct)
+{
+	if (!ct)
+		return;
+	if (ct->scc.fd >= 0)
+		close(ct->scc.fd);
+	free_argv(ct->features);
+	ct->features = NULL;
+	sc_free(ct->scc.recv);
+	ct->scc.recv = NULL;
+	sc_free(ct->scc.send);
+	ct->scc.send = NULL;
+	btr_remove_node(&ct->btrn);
+}
+
 /**
  * Close the connection to para_server and free all resources.
  *
  * \param ct Pointer to the client data.
  *
- * \sa client_open.
+ * \sa \ref client_open(), \ref client_disconnect().
  */
 void client_close(struct client_task *ct)
 {
 	if (!ct)
 		return;
-	if (ct->rc4c.fd >= 0)
-		close(ct->rc4c.fd);
+	client_disconnect(ct);
 	free(ct->user);
 	free(ct->config_file);
 	free(ct->key_file);
 	client_cmdline_parser_free(&ct->conf);
+	free(ct->challenge_hash);
+	sb_free(ct->sbc);
 	free(ct);
 }
 
@@ -69,19 +92,20 @@ static void client_pre_select(struct sched *s, struct task *t)
 	struct client_task *ct = container_of(t, struct client_task, task);
 	struct btr_node *btrn = ct->btrn;
 
-	if (ct->rc4c.fd < 0)
+	if (ct->scc.fd < 0)
 		return;
 	switch (ct->status) {
 	case CL_CONNECTED:
 	case CL_SENT_AUTH:
 	case CL_SENT_CH_RESPONSE:
 	case CL_SENT_COMMAND:
-		para_fd_set(ct->rc4c.fd, &s->rfds, &s->max_fileno);
+		para_fd_set(ct->scc.fd, &s->rfds, &s->max_fileno);
 		return;
 
 	case CL_RECEIVED_WELCOME:
 	case CL_RECEIVED_PROCEED:
-		para_fd_set(ct->rc4c.fd, &s->wfds, &s->max_fileno);
+	case CL_RECEIVED_CHALLENGE:
+		para_fd_set(ct->scc.fd, &s->wfds, &s->max_fileno);
 		return;
 
 	case CL_RECEIVING:
@@ -90,7 +114,7 @@ static void client_pre_select(struct sched *s, struct task *t)
 			if (ret < 0)
 				sched_min_delay(s);
 			else
-				para_fd_set(ct->rc4c.fd, &s->rfds,
+				para_fd_set(ct->scc.fd, &s->rfds,
 					&s->max_fileno);
 		}
 		return;
@@ -100,26 +124,194 @@ static void client_pre_select(struct sched *s, struct task *t)
 			if (ret < 0)
 				sched_min_delay(s);
 			else
-				para_fd_set(ct->rc4c.fd, &s->wfds,
+				para_fd_set(ct->scc.fd, &s->wfds,
 					&s->max_fileno);
 		}
 		return;
 	}
 }
 
-static ssize_t client_recv_buffer(struct client_task *ct, char *buf, size_t len)
+static int client_recv_buffer(struct client_task *ct, fd_set *rfds,
+		char *buf, size_t sz, size_t *n)
 {
-	ssize_t ret;
+	int ret;
 
 	if (ct->status < CL_SENT_CH_RESPONSE)
-		ret = recv_buffer(ct->rc4c.fd, buf, len);
-	else
-		ret = rc4_recv_buffer(&ct->rc4c, buf, len);
+		return read_nonblock(ct->scc.fd, buf, sz, rfds, n);
+
+	*n = 0;
+	ret = sc_recv_buffer(&ct->scc, buf, sz);
+	/*
+	 * sc_recv_buffer is used with blocking fds elsewhere, so it
+	 * does not use the nonblock-API. Therefore we need to
+	 * check for EOF and EAGAIN.
+	 */
 	if (ret == 0)
 		return -E_SERVER_EOF;
+	if (ret == -ERRNO_TO_PARA_ERROR(EAGAIN))
+		return 0;
+	if (ret < 0)
+		return ret;
+	*n = ret;
+	return 0;
+}
+
+static int send_sb(struct client_task *ct, void *buf, size_t numbytes,
+		enum sb_designator band, bool dont_free)
+{
+	int ret, fd = ct->scc.fd;
+	struct iovec iov[2];
+
+	if (!ct->sbc) {
+		struct sb_buffer sbb;
+		sb_transformation trafo = ct->status < CL_RECEIVED_PROCEED?
+			NULL : sc_trafo;
+		sbb = (typeof(sbb))SBB_INIT(band, buf, numbytes);
+		ct->sbc = sb_new_send(&sbb, dont_free, trafo, ct->scc.send);
+	}
+	ret = sb_get_send_buffers(ct->sbc, iov);
+	ret = xwritev(fd, iov, ret);
+	if (ret < 0) {
+		sb_free(ct->sbc);
+		ct->sbc = NULL;
+		return ret;
+	}
+	if (sb_sent(ct->sbc, ret)) {
+		ct->sbc = NULL;
+		return 1;
+	}
+	return 0;
+}
+
+static int recv_sb(struct client_task *ct, fd_set *rfds,
+		struct sb_buffer *result)
+{
+	int ret;
+	size_t n;
+	sb_transformation trafo;
+	void *trafo_context;
+	struct iovec iov;
+
+	if (!FD_ISSET(ct->scc.fd, rfds))
+		return 0;
+	if (ct->status < CL_SENT_CH_RESPONSE)
+		trafo = trafo_context = NULL;
+	else {
+		trafo = sc_trafo;
+		trafo_context = ct->scc.recv;
+	}
+	if (!ct->sbc)
+		ct->sbc = sb_new_recv(0, trafo, trafo_context);
+again:
+	sb_get_recv_buffer(ct->sbc, &iov);
+	ret = read_nonblock(ct->scc.fd, iov.iov_base, iov.iov_len, rfds, &n);
+	if (ret < 0) {
+		sb_free(ct->sbc);
+		ct->sbc = NULL;
+		return ret;
+	}
+	if (n == 0)
+		return 0;
+	if (!sb_received(ct->sbc, n, result))
+		goto again;
+	ct->sbc = NULL;
+	return 1;
+}
+
+
+static char **parse_features(char *buf)
+{
+	int i;
+	const char id[] = "\nFeatures: ";
+	char *p, *q, **features;
+
+	p = strstr(buf, id);
+	if (!p)
+		return NULL;
+	p += strlen(id);
+	q = strchr(p, '\n');
+	if (!q)
+		return NULL;
+	*q = '\0';
+	create_argv(p, ",", &features);
+	for (i = 0; features[i]; i++)
+		PARA_INFO_LOG("server feature: %s\n", features[i]);
+	return features;
+}
+
+static int dispatch_sbb(struct client_task *ct, struct sb_buffer *sbb)
+{
+	int ret;
+	const char *designator[] = {SB_DESIGNATORS_ARRAY};
+
+	if (!sbb)
+		return 0;
+	if (sbb->band < NUM_SB_DESIGNATORS)
+		PARA_DEBUG_LOG("band: %s\n", designator[sbb->band]);
+
+	switch (sbb->band) {
+	case SBD_OUTPUT:
+		if (iov_valid(&sbb->iov))
+			btr_add_output(sbb->iov.iov_base, sbb->iov.iov_len,
+				ct->btrn);
+		ret = 1;
+		goto out;
+	case SBD_DEBUG_LOG:
+	case SBD_INFO_LOG:
+	case SBD_NOTICE_LOG:
+	case SBD_WARNING_LOG:
+	case SBD_ERROR_LOG:
+	case SBD_CRIT_LOG:
+	case SBD_EMERG_LOG:
+		if (iov_valid(&sbb->iov)) {
+			int ll = sbb->band - SBD_DEBUG_LOG;
+			para_log(ll, "remote: %s", (char *)sbb->iov.iov_base);
+		}
+		ret = 1;
+		goto deallocate;
+	case SBD_EXIT__SUCCESS:
+		ret = -E_SERVER_CMD_SUCCESS;
+		goto deallocate;
+	case SBD_EXIT__FAILURE:
+		ret = -E_SERVER_CMD_FAILURE;
+		goto deallocate;
+	default:
+		PARA_ERROR_LOG("invalid band %d\n", sbb->band);
+		ret = -E_BAD_BAND;
+		goto deallocate;
+	}
+deallocate:
+	free(sbb->iov.iov_base);
+out:
+	sbb->iov.iov_base = NULL;
 	return ret;
 }
 
+static bool has_feature(const char *feature, struct client_task *ct)
+{
+	return find_arg(feature, ct->features) >= 0? true : false;
+}
+
+static int send_sb_command(struct client_task *ct)
+{
+	int i;
+	char *command, *p;
+	size_t len = 0;
+
+	if (ct->sbc)
+		return send_sb(ct, NULL, 0, 0, false);
+
+	for (i = 0; i < ct->conf.inputs_num; i++)
+		len += strlen(ct->conf.inputs[i]) + 1;
+	p = command = para_malloc(len);
+	for (i = 0; i < ct->conf.inputs_num; i++) {
+		strcpy(p, ct->conf.inputs[i]);
+		p += strlen(ct->conf.inputs[i]) + 1;
+	}
+	PARA_DEBUG_LOG("--> %s\n", command);
+	return send_sb(ct, command, len, SBD_COMMAND, false);
+}
+
 /**
  * The post select hook for client commands.
  *
@@ -133,94 +325,142 @@ static ssize_t client_recv_buffer(struct client_task *ct, char *buf, size_t len)
  *
  * \sa struct sched, struct task.
  */
-static void client_post_select(struct sched *s, struct task *t)
+static int client_post_select(struct sched *s, struct task *t)
 {
 	struct client_task *ct = container_of(t, struct client_task, task);
 	struct btr_node *btrn = ct->btrn;
 	int ret = 0;
+	size_t n;
 	char buf[CLIENT_BUFSIZE];
 
-	t->error = 0;
-	if (ct->rc4c.fd < 0)
-		return;
+	ret = task_get_notification(t);
+	if (ret < 0)
+		goto out;
+	if (ct->scc.fd < 0)
+		return 0;
 	switch (ct->status) {
 	case CL_CONNECTED: /* receive welcome message */
-		if (!FD_ISSET(ct->rc4c.fd, &s->rfds))
-			return;
-		ret = client_recv_buffer(ct, buf, sizeof(buf));
-		if (ret < 0)
-			goto err;
+		ret = client_recv_buffer(ct, &s->rfds, buf, sizeof(buf), &n);
+		if (ret < 0 || n == 0)
+			goto out;
+		ct->features = parse_features(buf);
 		ct->status = CL_RECEIVED_WELCOME;
-		return;
+		return 0;
 	case CL_RECEIVED_WELCOME: /* send auth command */
-		sprintf(buf, AUTH_REQUEST_MSG "%s", ct->user);
+		if (!FD_ISSET(ct->scc.fd, &s->wfds))
+			return 0;
+		if (has_feature("sideband", ct)) {
+			ct->use_sideband = true;
+			sprintf(buf, AUTH_REQUEST_MSG "%s sideband", ct->user);
+		} else
+			sprintf(buf, AUTH_REQUEST_MSG "%s", ct->user);
 		PARA_INFO_LOG("--> %s\n", buf);
-		if (!FD_ISSET(ct->rc4c.fd, &s->wfds))
-			return;
-		ret = send_buffer(ct->rc4c.fd, buf);
+		ret = write_buffer(ct->scc.fd, buf);
 		if (ret < 0)
-			goto err;
+			goto out;
 		ct->status = CL_SENT_AUTH;
-		return;
+		return 0;
 	case CL_SENT_AUTH:
 		/*
-		 * Receive challenge and rc4 keys, decrypt the challenge and
+		 * Receive challenge and session keys, decrypt the challenge and
 		 * send back the hash of the decrypted challenge.
 		 */
 		{
-		/* decrypted challenge/rc4 buffer */
+		/* decrypted challenge/session key buffer */
 		unsigned char crypt_buf[1024];
 		/* the SHA1 of the decrypted challenge */
-		unsigned char challenge_sha1[HASH_SIZE];
 
-		if (!FD_ISSET(ct->rc4c.fd, &s->rfds))
-			return;
-		ret = client_recv_buffer(ct, buf, sizeof(buf));
-		if (ret < 0)
-			goto err;
-		PARA_INFO_LOG("<-- [challenge] (%d bytes)\n", ret);
-		ret = para_decrypt_buffer(ct->key_file, crypt_buf,
-			(unsigned char *)buf, ret);
-		if (ret < 0)
-			goto err;
-		sha1_hash((char *)crypt_buf, CHALLENGE_SIZE, challenge_sha1);
-		RC4_set_key(&ct->rc4c.send_key, RC4_KEY_LEN,
-			crypt_buf + CHALLENGE_SIZE);
-		RC4_set_key(&ct->rc4c.recv_key, RC4_KEY_LEN,
-			crypt_buf + CHALLENGE_SIZE + RC4_KEY_LEN);
-		hash_to_asc(challenge_sha1, buf);
+		if (ct->use_sideband) {
+			struct sb_buffer sbb;
+			ret = recv_sb(ct, &s->rfds, &sbb);
+			if (ret <= 0)
+				goto out;
+			if (sbb.band != SBD_CHALLENGE) {
+				ret = -E_BAD_BAND;
+				free(sbb.iov.iov_base);
+					goto out;
+			}
+			n = sbb.iov.iov_len;
+			PARA_INFO_LOG("<-- [challenge] (%zu bytes)\n", n);
+			ret = priv_decrypt(ct->key_file, crypt_buf,
+				sbb.iov.iov_base, n);
+			free(sbb.iov.iov_base);
+			if (ret < 0)
+				goto out;
+		} else {
+			ret = client_recv_buffer(ct, &s->rfds, buf, sizeof(buf), &n);
+			if (ret < 0 || n == 0)
+				goto out;
+			PARA_INFO_LOG("<-- [challenge] (%zu bytes)\n", n);
+			ret = priv_decrypt(ct->key_file, crypt_buf,
+				(unsigned char *)buf, n);
+			if (ret < 0)
+				goto out;
+		}
+		ct->challenge_hash = para_malloc(HASH_SIZE);
+		hash_function((char *)crypt_buf, CHALLENGE_SIZE, ct->challenge_hash);
+		ct->scc.send = sc_new(crypt_buf + CHALLENGE_SIZE, SESSION_KEY_LEN);
+		ct->scc.recv = sc_new(crypt_buf + CHALLENGE_SIZE + SESSION_KEY_LEN,
+			SESSION_KEY_LEN);
+		hash_to_asc(ct->challenge_hash, buf);
 		PARA_INFO_LOG("--> %s\n", buf);
-		ret = send_bin_buffer(ct->rc4c.fd, (char *)challenge_sha1,
-			HASH_SIZE);
-		if (ret < 0)
-			goto err;
-		ct->status = CL_SENT_CH_RESPONSE;
-		return;
+		ct->status = CL_RECEIVED_CHALLENGE;
+		return 0;
 		}
+	case CL_RECEIVED_CHALLENGE:
+		if (ct->use_sideband) {
+			ret = send_sb(ct, ct->challenge_hash, HASH_SIZE,
+				SBD_CHALLENGE_RESPONSE, false);
+			if (ret != 0)
+				ct->challenge_hash = NULL;
+			if (ret <= 0)
+				goto out;
+		} else {
+			ret = write_all(ct->scc.fd, (char *)ct->challenge_hash, HASH_SIZE);
+			if (ret < 0)
+				goto out;
+		}
+		ct->status = CL_SENT_CH_RESPONSE;
+		goto out;
 	case CL_SENT_CH_RESPONSE: /* read server response */
 		{
-		size_t bytes_received;
-		if (!FD_ISSET(ct->rc4c.fd, &s->rfds))
-			return;
-		ret = client_recv_buffer(ct, buf, sizeof(buf));
-		if (ret < 0)
-			goto err;
-		bytes_received = ret;
+		if (ct->use_sideband) {
+			struct sb_buffer sbb;
+			ret = recv_sb(ct, &s->rfds, &sbb);
+			if (ret <= 0)
+				goto out;
+			free(sbb.iov.iov_base);
+			if (sbb.band != SBD_PROCEED)
+				ret = -E_BAD_BAND;
+			else
+				ct->status = CL_RECEIVED_PROCEED;
+			goto out;
+		}
+		ret = client_recv_buffer(ct, &s->rfds, buf, sizeof(buf), &n);
+		if (ret < 0 || n == 0)
+			goto out;
 		/* check if server has sent "Proceed" message */
 		ret = -E_CLIENT_AUTH;
-		if (bytes_received < PROCEED_MSG_LEN)
-			goto err;
+		if (n < PROCEED_MSG_LEN)
+			goto out;
 		if (!strstr(buf, PROCEED_MSG))
-			goto err;
+			goto out;
 		ct->status = CL_RECEIVED_PROCEED;
-		return;
+		return 0;
 		}
 	case CL_RECEIVED_PROCEED: /* concat args and send command */
 		{
 		int i;
 		char *command = NULL;
-		if (!FD_ISSET(ct->rc4c.fd, &s->wfds))
-			return;
+		if (!FD_ISSET(ct->scc.fd, &s->wfds))
+			return 0;
+		if (ct->use_sideband) {
+			ret = send_sb_command(ct);
+			if (ret <= 0)
+				goto out;
+			ct->status = CL_SENT_COMMAND;
+			return 0;
+		}
 		for (i = 0; i < ct->conf.inputs_num; i++) {
 			char *tmp = command;
 			command = make_message("%s\n%s", command?
@@ -229,33 +469,44 @@ static void client_post_select(struct sched *s, struct task *t)
 		}
 		command = para_strcat(command, EOC_MSG "\n");
 		PARA_DEBUG_LOG("--> %s\n", command);
-		ret = rc4_send_buffer(&ct->rc4c, command);
+		ret = sc_send_buffer(&ct->scc, command);
 		free(command);
 		if (ret < 0)
-			goto err;
+			goto out;
 		ct->status = CL_SENT_COMMAND;
-		return;
+		return 0;
 		}
 	case CL_SENT_COMMAND:
 		{
 		char *buf2;
-		if (!FD_ISSET(ct->rc4c.fd, &s->rfds))
-			return;
+		if (ct->use_sideband) {
+			struct sb_buffer sbb;
+			ret = recv_sb(ct, &s->rfds, &sbb);
+			if (ret <= 0)
+				goto out;
+			if (sbb.band == SBD_AWAITING_DATA) {
+				ct->status = CL_SENDING;
+				free(sbb.iov.iov_base);
+				goto out;
+			}
+			ct->status = CL_RECEIVING;
+			ret = dispatch_sbb(ct, &sbb);
+			goto out;
+		}
 		/* can not use "buf" here because we need a malloced buffer */
 		buf2 = para_malloc(CLIENT_BUFSIZE);
-		ret = client_recv_buffer(ct, buf2, CLIENT_BUFSIZE);
-		if (ret < 0) {
-			free(buf2);
-			goto err;
-		}
-		if (strstr(buf2, AWAITING_DATA_MSG)) {
+		ret = client_recv_buffer(ct, &s->rfds, buf2, CLIENT_BUFSIZE, &n);
+		if (n > 0) {
+			if (strstr(buf2, AWAITING_DATA_MSG)) {
+				free(buf2);
+				ct->status = CL_SENDING;
+				return 0;
+			}
+			ct->status = CL_RECEIVING;
+			btr_add_output(buf2, n, btrn);
+		} else
 			free(buf2);
-			ct->status = CL_SENDING;
-			return;
-		}
-		ct->status = CL_RECEIVING;
-		btr_add_output(buf2, ret, btrn);
-		return;
+		goto out;
 		}
 	case CL_SENDING:
 		{
@@ -263,115 +514,134 @@ static void client_post_select(struct sched *s, struct task *t)
 		size_t sz;
 		ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
 		if (ret < 0)
-			goto err;
+			goto out;
 		if (ret == 0)
-			return;
-		if (!FD_ISSET(ct->rc4c.fd, &s->wfds))
-			return;
+			return 0;
+		if (!FD_ISSET(ct->scc.fd, &s->wfds))
+			return 0;
 		sz = btr_next_buffer(btrn, &buf2);
-		ret = rc4_send_bin_buffer(&ct->rc4c, buf2, sz);
+		ret = sc_send_bin_buffer(&ct->scc, buf2, sz);
 		if (ret < 0)
-			goto err;
+			goto out;
 		btr_consume(btrn, sz);
-		return;
+		return 0;
 		}
 	case CL_RECEIVING:
 		{
 		char *buf2;
 		ret = btr_node_status(btrn, 0, BTR_NT_ROOT);
 		if (ret < 0)
-			goto err;
+			goto out;
 		if (ret == 0)
-			return;
-		if (!FD_ISSET(ct->rc4c.fd, &s->rfds))
-			return;
+			return 0;
+		/*
+		 * The FD_ISSET() is not strictly necessary, but is allows us
+		 * to skip the malloc below if there is nothing to read anyway.
+		 */
+		if (!FD_ISSET(ct->scc.fd, &s->rfds))
+			return 0;
+		if (ct->use_sideband) {
+			struct sb_buffer sbb;
+			ret = recv_sb(ct, &s->rfds, &sbb);
+			if (ret > 0)
+				ret = dispatch_sbb(ct, &sbb);
+			goto out;
+		}
 		buf2 = para_malloc(CLIENT_BUFSIZE);
-		ret = client_recv_buffer(ct, buf2, CLIENT_BUFSIZE);
-		if (ret < 0) {
+		ret = client_recv_buffer(ct, &s->rfds, buf2, CLIENT_BUFSIZE, &n);
+		if (n > 0) {
+			buf2 = para_realloc(buf2, n);
+			btr_add_output(buf2, n, btrn);
+		} else
 			free(buf2);
-			goto err;
-		}
-		buf2 = para_realloc(buf2, ret);
-		btr_add_output(buf2, ret, btrn);
-		return;
+		goto out;
 		}
 	}
-err:
-	t->error = ret;
+out:
 	if (ret < 0) {
-		if (ret != -E_SERVER_EOF && ret != -E_BTR_EOF)
-			PARA_ERROR_LOG("%s\n", para_strerror(-t->error));
-		btr_remove_node(btrn);
+		if (!ct->use_sideband && ret != -E_SERVER_EOF &&
+				ret != -E_BTR_EOF && ret != -E_EOF)
+			PARA_ERROR_LOG("%s\n", para_strerror(-ret));
+		btr_remove_node(&ct->btrn);
 	}
+	return ret;
 }
 
-/* connect to para_server and register the client task */
-static int client_connect(struct client_task *ct)
+/**
+ * Connect to para_server and register the client task.
+ *
+ * \param ct The initialized client task structure.
+ * \param s The scheduler instance to register the client task to.
+ * \param parent The parent node of the client btr node.
+ * \param child The child node of the client node.
+ *
+ * The client task structure given by \a ct  must be allocated and initialized
+ * by \ref client_parse_config() before this function is called.
+ *
+ * \return Standard.
+ */
+int client_connect(struct client_task *ct, struct sched *s,
+		struct btr_node *parent, struct btr_node *child)
 {
 	int ret;
 
-	ct->rc4c.fd = -1;
+	PARA_NOTICE_LOG("connecting %s:%d\n", ct->conf.hostname_arg,
+		ct->conf.server_port_arg);
+	ct->scc.fd = -1;
 	ret = para_connect_simple(IPPROTO_TCP, ct->conf.hostname_arg,
 					       ct->conf.server_port_arg);
 	if (ret < 0)
 		return ret;
-	ct->rc4c.fd = ret;
-	ct->status = CL_CONNECTED;
-	ret = mark_fd_nonblocking(ct->rc4c.fd);
+	ct->scc.fd = ret;
+	ret = mark_fd_nonblocking(ct->scc.fd);
 	if (ret < 0)
 		goto err_out;
+	ct->status = CL_CONNECTED;
+	ct->btrn = btr_new_node(&(struct btr_node_description)
+		EMBRACE(.name = "client", .parent = parent, .child = child));
 	ct->task.pre_select = client_pre_select;
 	ct->task.post_select = client_post_select;
+	ct->task.error = 0;
 	sprintf(ct->task.status, "client");
-	register_task(&ct->task);
+	register_task(s, &ct->task);
 	return 1;
 err_out:
-	close(ct->rc4c.fd);
-	ct->rc4c.fd = -1;
+	close(ct->scc.fd);
+	ct->scc.fd = -1;
 	return ret;
 }
 
 /**
- * Open connection to para_server.
+ * Parse a client configuration.
  *
  * \param argc Usual argument count.
  * \param argv Usual argument vector.
- * \param ct_ptr Points to dynamically allocated and initialized client task
- * struct upon successful return.
+ * \param ct_ptr Filled in by this function.
  * \param loglevel If not \p NULL, the number of the loglevel is stored here.
- * \param parent Add the new buffer tree node as a child of this node.
- * \param child Add the new buffer tree node as a parent of this node.
  *
- * Check the command line options given by \a argc and argv, set default values
- * for user name and rsa key file, read further option from the config file.
- * Finally, establish a connection to para_server.
+ * This checks the command line options given by \a argc and \a argv, sets
+ * default values for the user name and the name of the rsa key file and reads
+ * further options from the config file.
  *
- * \return Standard.
+ * Upon successful return, \a ct_ptr points to a dynamically allocated and
+ * initialized client task struct.
+ *
+ * \return The number of non-option arguments in \a argc/argv on success,
+ * negative on errors.
  */
-int client_open(int argc, char *argv[], struct client_task **ct_ptr,
-		int *loglevel, struct btr_node *parent, struct btr_node *child)
+int client_parse_config(int argc, char *argv[], struct client_task **ct_ptr,
+		int *loglevel)
 {
 	char *home = para_homedir();
 	int ret;
 	struct client_task *ct = para_calloc(sizeof(struct client_task));
 
-	ct->btrn = btr_new_node(&(struct btr_node_description)
-		EMBRACE(.name = "client", .parent = parent, .child = child));
 	*ct_ptr = ct;
-	ct->rc4c.fd = -1;
+	ct->scc.fd = -1;
 	ret = -E_CLIENT_SYNTAX;
 	if (client_cmdline_parser(argc, argv, &ct->conf))
 		goto out;
 	HANDLE_VERSION_FLAG("client", ct->conf);
-	ret = -E_CLIENT_SYNTAX;
-	if (!ct->conf.inputs_num)
-		goto out;
-	ct->user = ct->conf.user_given?
-		para_strdup(ct->conf.user_arg) : para_logname();
-
-	ct->key_file = ct->conf.key_file_given?
-		para_strdup(ct->conf.key_file_arg) :
-		make_message("%s/.paraslash/key.%s", home, ct->user);
 
 	ct->config_file = ct->conf.config_file_given?
 		para_strdup(ct->conf.config_file_arg) :
@@ -394,22 +664,71 @@ int client_open(int argc, char *argv[], struct client_task **ct_ptr,
 			&ct->conf, &params))
 			goto out;
 	}
+	ct->user = ct->conf.user_given?
+		para_strdup(ct->conf.user_arg) : para_logname();
+
+	if (ct->conf.key_file_given)
+		ct->key_file = para_strdup(ct->conf.key_file_arg);
+	else {
+		ct->key_file = make_message("%s/.paraslash/key.%s",
+			home, ct->user);
+		if (!file_exists(ct->key_file)) {
+			free(ct->key_file);
+			ct->key_file = make_message("%s/.ssh/id_rsa", home);
+		}
+	}
+
 	if (loglevel)
 		*loglevel = get_loglevel_by_name(ct->conf.loglevel_arg);
 	PARA_INFO_LOG("loglevel: %s\n", ct->conf.loglevel_arg);
 	PARA_INFO_LOG("config_file: %s\n", ct->config_file);
 	PARA_INFO_LOG("key_file: %s\n", ct->key_file);
-	PARA_NOTICE_LOG("connecting %s:%d\n", ct->conf.hostname_arg,
-		ct->conf.server_port_arg);
-	ret = client_connect(ct);
+	ret = ct->conf.inputs_num;
 out:
 	free(home);
 	if (ret < 0) {
 		PARA_ERROR_LOG("%s\n", para_strerror(-ret));
-		btr_remove_node(ct->btrn);
-		btr_free_node(ct->btrn);
 		client_close(ct);
 		*ct_ptr = NULL;
 	}
 	return ret;
 }
+
+/**
+ * Parse the client configuration and open a connection to para_server.
+ *
+ * \param argc See \ref client_parse_config.
+ * \param argv See \ref client_parse_config.
+ * \param ct_ptr See \ref client_parse_config.
+ * \param loglevel See \ref client_parse_config.
+ * \param parent See \ref client_connect().
+ * \param child See \ref client_connect().
+ * \param sched See \ref client_connect().
+ *
+ * This function combines client_parse_config() and client_connect(). It is
+ * considered a syntax error if no command was given, i.e. if the number
+ * of non-option arguments is zero.
+ *
+ * \return Standard.
+ */
+int client_open(int argc, char *argv[], struct client_task **ct_ptr,
+		int *loglevel, struct btr_node *parent, struct btr_node *child,
+		struct sched *sched)
+{
+	int ret = client_parse_config(argc, argv, ct_ptr, loglevel);
+
+	if (ret < 0)
+		return ret;
+	if (ret == 0) {
+		ret = -E_CLIENT_SYNTAX;
+		goto fail;
+	}
+	ret = client_connect(*ct_ptr, sched, parent, child);
+	if (ret < 0)
+		goto fail;
+	return 1;
+fail:
+	client_close(*ct_ptr);
+	*ct_ptr = NULL;
+	return ret;
+}