Add libctrl, an SNMP-like control interface

In contrast to the VTY interface the control interface is meant to be
used by programs.
This patch adds basic support, no commands are defined.

4 files changed, 820 insertions, 1 deletions

diff --git a/openbsc/src/Makefile.am b/openbsc/src/Makefile.am
index df7b936e7..c7de811f3 100644
--- a/openbsc/src/Makefile.am
+++ b/openbsc/src/Makefile.am
@@ -2,7 +2,7 @@ INCLUDES = $(all_includes) -I$(top_srcdir)/include -I$(top_builddir)
 AM_CFLAGS=-Wall $(LIBOSMOCORE_CFLAGS) $(LIBOSMOGSM_CFLAGS) $(LIBOSMOGSM_CFLAGS) $(LIBOSMOVTY_CFLAGS) $(COVERAGE_CFLAGS)
 AM_LDFLAGS = $(LIBOSMOCORE_LIBS) $(LIBOSMOGSM_LIBS) $(COVERAGE_LDFLAGS)
 
-SUBDIRS = libcommon libabis libmgcp libbsc libmsc libtrau osmo-nitb osmo-bsc_mgcp utils ipaccess libgb gprs
+SUBDIRS = libcommon libabis libmgcp libbsc libmsc libtrau libctrl osmo-nitb osmo-bsc_mgcp utils ipaccess libgb gprs
 
 # Conditional modules
 if BUILD_NAT
diff --git a/openbsc/src/libctrl/Makefile.am b/openbsc/src/libctrl/Makefile.am
new file mode 100644
index 000000000..286929b89
--- /dev/null
+++ b/openbsc/src/libctrl/Makefile.am
@@ -0,0 +1,7 @@
+INCLUDES = $(all_includes) -I$(top_srcdir)/include -I$(top_builddir)
+AM_CFLAGS=-Wall $(LIBOSMOCORE_CFLAGS) $(LIBOSMOVTY_CFLAGS) $(COVERAGE_CFLAGS)
+AM_LDFLAGS = $(LIBOSMOCORE_LIBS) $(COVERAGE_LDFLAGS)
+
+noinst_LIBRARIES = libctrl.a
+
+libctrl_a_SOURCES =	control_if.c control_cmd.c
diff --git a/openbsc/src/libctrl/control_cmd.c b/openbsc/src/libctrl/control_cmd.c
new file mode 100644
index 000000000..06af3b320
--- /dev/null
+++ b/openbsc/src/libctrl/control_cmd.c
@@ -0,0 +1,443 @@
+/* SNMP-like status interface
+ *
+ * (C) 2010-2011 by Daniel Willmann <daniel@totalueberwachung.de>
+ * (C) 2010-2011 by On-Waves
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <ctype.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <openbsc/control_cmd.h>
+#include <openbsc/debug.h>
+#include <openbsc/vty.h>
+
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/talloc.h>
+
+#include <osmocom/vty/command.h>
+#include <osmocom/vty/vector.h>
+
+extern vector ctrl_node_vec;
+
+static struct ctrl_cmd_map ccm[] = {
+	{"GET", CTRL_TYPE_GET},
+	{"SET", CTRL_TYPE_SET},
+	{"GET_REPLY", CTRL_TYPE_GET_REPLY},
+	{"SET_REPLY", CTRL_TYPE_SET_REPLY},
+	{"TRAP", CTRL_TYPE_TRAP},
+	{"ERROR", CTRL_TYPE_ERROR},
+	{NULL}
+};
+
+int ctrl_cmd_str2type(char *s)
+{
+	int i;
+	for (i=0; ccm[i].cmd != NULL; i++) {
+		if (strcasecmp(s, ccm[i].cmd) == 0)
+			return ccm[i].type;
+	}
+	return CTRL_TYPE_UNKNOWN;
+}
+
+char *ctrl_cmd_type2str(int type)
+{
+	int i;
+	for (i=0; ccm[i].cmd != NULL; i++) {
+		if (ccm[i].type == type)
+			return ccm[i].cmd;
+	}
+	return NULL;
+}
+
+/* Functions from libosmocom */
+extern vector cmd_make_descvec(const char *string, const char *descstr);
+
+/* Get the ctrl_cmd_element that matches this command */
+static struct ctrl_cmd_element *ctrl_cmd_get_element_match(vector vline, vector node)
+{
+	int index, j;
+	const char *desc;
+	struct ctrl_cmd_element *cmd_el;
+	struct ctrl_cmd_struct *cmd_desc;
+	char *str;
+
+	for (index = 0; index < vector_active(node); index++) {
+		if ((cmd_el = vector_slot(node, index))) {
+			cmd_desc = &cmd_el->strcmd;
+			if (cmd_desc->nr_commands > vector_active(vline))
+				continue;
+			for (j =0; j < vector_active(vline); j++) {
+				str = vector_slot(vline, j);
+				desc = cmd_desc->command[j];
+				if (desc[0] == '*')
+					return cmd_el; /* Partial match */
+				if (strcmp(desc, str) != 0)
+					break;
+			}
+			/* We went through all the elements and all matched */
+			if (j == cmd_desc->nr_commands)
+				return cmd_el;
+		}
+	}
+
+	return NULL;
+}
+
+int ctrl_cmd_exec(vector vline, struct ctrl_cmd *command, vector node, void *data)
+{
+	int ret = CTRL_CMD_ERROR;
+	struct ctrl_cmd_element *cmd_el;
+
+	if ((command->type != CTRL_TYPE_GET) && (command->type != CTRL_TYPE_SET)) {
+		command->reply = "Trying to execute something not GET or SET";
+		goto out;
+	}
+	if ((command->type == CTRL_TYPE_SET) && (!command->value)) {
+		command->reply = "SET without a value";
+		goto out;
+	}
+
+	if (!vline)
+		goto out;
+
+	cmd_el = ctrl_cmd_get_element_match(vline, node);
+
+	if (!cmd_el) {
+		command->reply = "Command not found";
+		goto out;
+	}
+
+	if (command->type == CTRL_TYPE_SET) {
+		if (!cmd_el->set) {
+			command->reply = "SET not implemented";
+			goto out;
+		}
+		if (cmd_el->verify) {
+			if ((ret = cmd_el->verify(command, command->value, data))) {
+				ret = CTRL_CMD_ERROR;
+				command->reply = "Value failed verification.";
+				goto out;
+			}
+		} else if (cmd_el->param) {
+			LOGP(DINP, LOGL_NOTICE, "Parameter verification unimplemented, continuing without\n");
+		}
+		ret =  cmd_el->set(command, data);
+		goto out;
+	} else if (command->type == CTRL_TYPE_GET) {
+		if (!cmd_el->get) {
+			command->reply = "GET not implemented";
+			goto out;
+		}
+		ret = cmd_el->get(command, data);
+		goto out;
+	}
+out:
+	if (ret == CTRL_CMD_REPLY) {
+		if (command->type == CTRL_TYPE_SET) {
+			command->type = CTRL_TYPE_SET_REPLY;
+		} else if (command->type == CTRL_TYPE_GET) {
+			command->type = CTRL_TYPE_GET_REPLY;
+		}
+	} else if (ret == CTRL_CMD_ERROR) {
+		command->type = CTRL_TYPE_ERROR;
+	}
+	return ret;
+}
+
+static void add_word(struct ctrl_cmd_struct *cmd,
+		     const char *start, const char *end)
+{
+	if (!cmd->command) {
+		cmd->command = talloc_zero_array(tall_vty_vec_ctx,
+						 char*, 1);
+		cmd->nr_commands = 0;
+	} else {
+		cmd->command = talloc_realloc(tall_vty_vec_ctx,
+					      cmd->command, char*,
+					      cmd->nr_commands + 1);
+	}
+
+	cmd->command[cmd->nr_commands++] = talloc_strndup(cmd->command,
+							  start, end - start);
+}
+
+static void create_cmd_struct(struct ctrl_cmd_struct *cmd, const char *name)
+{
+	const char *cur, *word;
+
+	for (cur = name, word = NULL; cur[0] != '\0'; ++cur) {
+		/* warn about optionals */
+		if (cur[0] == '(' || cur[0] == ')' || cur[0] == '|') {
+			LOGP(DINP, LOGL_ERROR,
+			     "Optionals are not supported in '%s'\n", name);
+			goto failure;
+		}
+
+		if (isspace(cur[0])) {
+			if (word) {
+				add_word(cmd, word, cur);
+				word = NULL;
+			}
+			continue;
+		}
+
+		if (!word)
+			word = cur;
+	}
+
+	if (word)
+		add_word(cmd, word, cur);
+
+	return;
+failure:
+	cmd->nr_commands = 0;
+	talloc_free(cmd->command);
+}
+
+int ctrl_cmd_install(enum ctrl_node_type node, struct ctrl_cmd_element *cmd)
+{
+	vector cmds_vec;
+
+	cmds_vec = vector_lookup_ensure(ctrl_node_vec, node);
+
+	if (!cmds_vec) {
+		cmds_vec = vector_init(5);
+		if (!cmds_vec) {
+			LOGP(DINP, LOGL_ERROR, "vector_init failed.\n");
+			return -ENOMEM;
+		}
+		vector_set_index(ctrl_node_vec, node, cmds_vec);
+	}
+
+	vector_set(cmds_vec, cmd);
+
+	create_cmd_struct(&cmd->strcmd, cmd->name);
+	return 0;
+}
+
+struct ctrl_cmd *ctrl_cmd_parse(void *ctx, struct msgb *msg)
+{
+	char *str, *tmp, *saveptr = NULL;
+	char *var, *val;
+	struct ctrl_cmd *cmd;
+
+	cmd = talloc_zero(ctx, struct ctrl_cmd);
+	if (!cmd) {
+		LOGP(DINP, LOGL_ERROR, "Failed to allocate.\n");
+		return NULL;
+	}
+
+	/* Make sure input is NULL terminated */
+	msgb_put_u8(msg, 0);
+	str = (char *) msg->l2h;
+
+	tmp = strtok_r(str, " ",  &saveptr);
+	if (!tmp) {
+		cmd->type = CTRL_TYPE_ERROR;
+		cmd->id = "err";
+		cmd->reply = "Request malformed";
+		goto err;
+	}
+
+	cmd->type = ctrl_cmd_str2type(tmp);
+	if (cmd->type == CTRL_TYPE_UNKNOWN) {
+		cmd->type = CTRL_TYPE_ERROR;
+		cmd->id = "err";
+		cmd->reply = "Request type unknown";
+		goto err;
+	}
+
+	tmp = strtok_r(NULL, " ",  &saveptr);
+
+	if (!tmp) {
+		cmd->type = CTRL_TYPE_ERROR;
+		cmd->id = "err";
+		cmd->reply = "Missing ID";
+		goto err;
+	}
+	cmd->id = talloc_strdup(cmd, tmp);
+	if (!cmd->id)
+		goto oom;
+
+	switch (cmd->type) {
+		case CTRL_TYPE_GET:
+			var = strtok_r(NULL, " ", &saveptr);
+			if (!var) {
+				cmd->type = CTRL_TYPE_ERROR;
+				cmd->reply = "GET incomplete";
+				LOGP(DINP, LOGL_NOTICE, "GET Command incomplete\n");
+				goto err;
+			}
+			cmd->variable = talloc_strdup(cmd, var);
+			LOGP(DINP, LOGL_DEBUG, "Command: GET %s\n", cmd->variable);
+			break;
+		case CTRL_TYPE_SET:
+			var = strtok_r(NULL, " ", &saveptr);
+			val = strtok_r(NULL, " ", &saveptr);
+			if (!var || !val) {
+				cmd->type = CTRL_TYPE_ERROR;
+				cmd->reply = "SET incomplete";
+				LOGP(DINP, LOGL_NOTICE, "SET Command incomplete\n");
+				goto err;
+			}
+			cmd->variable = talloc_strdup(cmd, var);
+			cmd->value = talloc_strdup(cmd, val);
+			if (!cmd->variable || !cmd->value)
+				goto oom;
+			LOGP(DINP, LOGL_DEBUG, "Command: SET %s = %s\n", cmd->variable, cmd->value);
+			break;
+		case CTRL_TYPE_GET_REPLY:
+		case CTRL_TYPE_SET_REPLY:
+		case CTRL_TYPE_TRAP:
+			var = strtok_r(NULL, " ", &saveptr);
+			val = strtok_r(NULL, " ", &saveptr);
+			if (!var || !val) {
+				cmd->type = CTRL_TYPE_ERROR;
+				cmd->reply = "Trap/Reply incomplete";
+				LOGP(DINP, LOGL_NOTICE, "Trap/Reply incomplete\n");
+				goto err;
+			}
+			cmd->variable = talloc_strdup(cmd, var);
+			cmd->reply = talloc_strdup(cmd, val);
+			if (!cmd->variable || !cmd->reply)
+				goto oom;
+			LOGP(DINP, LOGL_DEBUG, "Command: TRAP/REPLY %s: %s\n", cmd->variable, cmd->reply);
+			break;
+		case CTRL_TYPE_ERROR:
+			var = strtok_r(NULL, "\0", &saveptr);
+			if (!var) {
+				cmd->reply = "";
+				goto err;
+			}
+			cmd->reply = talloc_strdup(cmd, var);
+			if (!cmd->reply)
+				goto oom;
+			LOGP(DINP, LOGL_DEBUG, "Command: ERROR %s\n", cmd->reply);
+			break;
+		case CTRL_TYPE_UNKNOWN:
+		default:
+			cmd->type = CTRL_TYPE_ERROR;
+			cmd->reply = "Unknown type";
+			goto err;
+	}
+
+	return cmd;
+oom:
+	cmd->type = CTRL_TYPE_ERROR;
+	cmd->id = "err";
+	cmd->reply = "OOM";
+err:
+	talloc_free(cmd);
+	return NULL;
+}
+
+struct msgb *ctrl_cmd_make(struct ctrl_cmd *cmd)
+{
+	struct msgb *msg;
+	char *type, *tmp;
+
+	if (!cmd->id)
+		return NULL;
+
+	msg = msgb_alloc_headroom(4096, 128, "ctrl command make");
+	if (!msg)
+		return NULL;
+
+	type = ctrl_cmd_type2str(cmd->type);
+
+	switch (cmd->type) {
+	case CTRL_TYPE_GET:
+		if (!cmd->variable)
+			goto err;
+
+		tmp = talloc_asprintf(cmd, "%s %s %s", type, cmd->id, cmd->variable);
+		if (!tmp) {
+			LOGP(DINP, LOGL_ERROR, "Failed to allocate cmd.\n");
+			goto err;
+		}
+
+		msg->l2h = msgb_put(msg, strlen(tmp));
+		memcpy(msg->l2h, tmp, strlen(tmp));
+		talloc_free(tmp);
+		break;
+	case CTRL_TYPE_SET:
+		if (!cmd->variable || !cmd->value)
+			goto err;
+
+		tmp = talloc_asprintf(cmd, "%s %s %s %s", type, cmd->id, cmd->variable,
+				cmd->value);
+		if (!tmp) {
+			LOGP(DINP, LOGL_ERROR, "Failed to allocate cmd.\n");
+			goto err;
+		}
+
+		msg->l2h = msgb_put(msg, strlen(tmp));
+		memcpy(msg->l2h, tmp, strlen(tmp));
+		talloc_free(tmp);
+		break;
+	case CTRL_TYPE_GET_REPLY:
+	case CTRL_TYPE_SET_REPLY:
+	case CTRL_TYPE_TRAP:
+		if (!cmd->variable || !cmd->reply)
+			goto err;
+
+		tmp = talloc_asprintf(cmd, "%s %s %s %s", type, cmd->id, cmd->variable,
+				cmd->reply);
+		if (!tmp) {
+			LOGP(DINP, LOGL_ERROR, "Failed to allocate cmd.\n");
+			goto err;
+		}
+
+		msg->l2h = msgb_put(msg, strlen(tmp));
+		memcpy(msg->l2h, tmp, strlen(tmp));
+		talloc_free(tmp);
+		break;
+	case CTRL_TYPE_ERROR:
+		if (!cmd->reply)
+			goto err;
+
+		tmp = talloc_asprintf(cmd, "%s %s %s", type, cmd->id,
+				cmd->reply);
+		if (!tmp) {
+			LOGP(DINP, LOGL_ERROR, "Failed to allocate cmd.\n");
+			goto err;
+		}
+
+		msg->l2h = msgb_put(msg, strlen(tmp));
+		memcpy(msg->l2h, tmp, strlen(tmp));
+		talloc_free(tmp);
+		break;
+	default:
+		LOGP(DINP, LOGL_NOTICE, "Unknown command type %i\n", cmd->type);
+		goto err;
+		break;
+	}
+
+	return msg;
+
+err:
+	msgb_free(msg);
+	return NULL;
+}
diff --git a/openbsc/src/libctrl/control_if.c b/openbsc/src/libctrl/control_if.c
new file mode 100644
index 000000000..a607b10bc
--- /dev/null
+++ b/openbsc/src/libctrl/control_if.c
@@ -0,0 +1,369 @@
+/* SNMP-like status interface
+ *
+ * (C) 2010-2011 by Daniel Willmann <daniel@totalueberwachung.de>
+ * (C) 2010-2011 by On-Waves
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <arpa/inet.h>
+
+#include <netinet/tcp.h>
+
+#include <sys/fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+
+#include <openbsc/control_cmd.h>
+#include <openbsc/debug.h>
+#include <openbsc/e1_input.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/ipaccess.h>
+#include <openbsc/socket.h>
+#include <openbsc/subchan_demux.h>
+
+#include <openbsc/abis_rsl.h>
+#include <openbsc/abis_nm.h>
+
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/talloc.h>
+
+#include <osmocom/gsm/tlv.h>
+
+#include <osmocom/vty/command.h>
+#include <osmocom/vty/vector.h>
+
+struct ctrl_handle {
+	struct osmo_fd listen_fd;
+	struct gsm_network *gsmnet;
+};
+
+vector ctrl_node_vec;
+
+int ctrl_cmd_send(struct osmo_wqueue *queue, struct ctrl_cmd *cmd)
+{
+	int ret;
+	struct msgb *msg;
+
+	msg = ctrl_cmd_make(cmd);
+	if (!msg) {
+		LOGP(DINP, LOGL_ERROR, "Could not generate msg\n");
+		return -1;
+	}
+
+	ipaccess_prepend_header_ext(msg, IPAC_PROTO_EXT_CTRL);
+	ipaccess_prepend_header(msg, IPAC_PROTO_OSMO);
+
+	ret = osmo_wqueue_enqueue(queue, msg);
+	if (ret != 0) {
+		LOGP(DINP, LOGL_ERROR, "Failed to enqueue the command.\n");
+		msgb_free(msg);
+	}
+	return ret;
+}
+
+int ctrl_cmd_handle(struct ctrl_cmd *cmd, void *data)
+{
+	char *token, *request;
+	int num, i, j, ret, node;
+	struct gsm_network *gsmnet = data;
+
+	struct gsm_network *net = NULL;
+	struct gsm_bts *bts = NULL;
+	struct gsm_bts_trx *trx = NULL;
+	struct gsm_bts_trx_ts *ts = NULL;
+	vector vline, cmdvec, cmds_vec;
+
+	ret = CTRL_CMD_ERROR;
+	cmd->reply = "Someone forgot to fill in the reply.";
+	cmd->node = NULL;
+	node = CTRL_NODE_ROOT;
+
+	request = talloc_strdup(tall_bsc_ctx, cmd->variable);
+	if (!request)
+		goto err;
+
+	for (i=0;i<strlen(request);i++) {
+		if (request[i] == '.')
+			request[i] = ' ';
+	}
+
+	vline = cmd_make_strvec(request);
+	talloc_free(request);
+	if (!vline)
+		goto err;
+
+	for (i=0;i<vector_active(vline);i++) {
+		token = vector_slot(vline, i);
+		/* TODO: We need to make sure that the following chars are digits
+		 * and/or use strtol to check if number conversion was successful
+		 * Right now something like net.bts_stats will not work */
+		if (!strcmp(token, "net")) {
+			net = gsmnet;
+			if (!net)
+				break;
+			cmd->node = net;
+			node = CTRL_NODE_NET;
+		} else if (!strncmp(token, "bts", 3)) {
+			if (!net)
+				break;
+			num = atoi(&token[3]);
+			bts = gsm_bts_num(net, num);
+			if (!bts)
+				break;
+			cmd->node = bts;
+			node = CTRL_NODE_BTS;
+		} else if (!strncmp(token, "trx", 3)) {
+			if (!bts)
+				break;
+			num = atoi(&token[3]);
+			trx = gsm_bts_trx_num(bts, num);
+			if (!trx)
+				break;
+			cmd->node = trx;
+			node = CTRL_NODE_TRX;
+		} else if (!strncmp(token, "ts", 2)) {
+			if (!trx)
+				break;
+			num = atoi(&token[2]);
+			if ((num >= 0) && (num < TRX_NR_TS))
+				ts = &trx->ts[num];
+			if (!ts)
+				break;
+			cmd->node = ts;
+			node = CTRL_NODE_TS;
+		} else {
+			/* If we're here the rest must be the command */
+			cmdvec = vector_init(vector_active(vline)-i);
+			for (j=i; j<vector_active(vline); j++) {
+				vector_set(cmdvec, vector_slot(vline, j));
+			}
+
+			/* Get the command vector of the right node */
+			cmds_vec = vector_lookup(ctrl_node_vec, node);
+
+			if (!cmds_vec) {
+				cmd->reply = "Command not found";
+				vector_free(cmdvec);
+				break;
+			}
+
+			ret = ctrl_cmd_exec(cmdvec, cmd, cmds_vec, data);
+
+			vector_free(cmdvec);
+			break;
+		}
+	}
+
+	cmd_free_strvec(vline);
+
+err:
+	if (ret == CTRL_CMD_ERROR)
+		cmd->type = CTRL_TYPE_ERROR;
+	return ret;
+}
+
+static void control_close_conn(struct ctrl_connection *ccon)
+{
+	close(ccon->write_queue.bfd.fd);
+	osmo_fd_unregister(&ccon->write_queue.bfd);
+	if (ccon->closed_cb)
+		ccon->closed_cb(ccon);
+	talloc_free(ccon);
+}
+
+static int handle_control_read(struct osmo_fd * bfd)
+{
+	int ret = -1, error;
+	struct osmo_wqueue *queue;
+	struct ctrl_connection *ccon;
+	struct ipaccess_head *iph;
+	struct ipaccess_head_ext *iph_ext;
+	struct msgb *msg;
+	struct ctrl_cmd *cmd;
+	struct ctrl_handle *ctrl = bfd->data;
+
+	queue = container_of(bfd, struct osmo_wqueue, bfd);
+	ccon = container_of(queue, struct ctrl_connection, write_queue);
+
+	msg = ipaccess_read_msg(bfd, &error);
+
+	if (!msg) {
+		if (error == 0)
+			LOGP(DINP, LOGL_INFO, "The control connection was closed\n");
+		else
+			LOGP(DINP, LOGL_ERROR, "Failed to parse ip access message: %d\n", error);
+
+		goto err;
+	}
+
+	if (msg->len < sizeof(*iph) + sizeof(*iph_ext)) {
+		LOGP(DINP, LOGL_ERROR, "The message is too short.\n");
+		goto err;
+	}
+
+	iph = (struct ipaccess_head *) msg->data;
+	if (iph->proto != IPAC_PROTO_OSMO) {
+		LOGP(DINP, LOGL_ERROR, "Protocol mismatch. We got 0x%x\n", iph->proto);
+		goto err;
+	}
+
+	iph_ext = (struct ipaccess_head_ext *) iph->data;
+	if (iph_ext->proto != IPAC_PROTO_EXT_CTRL) {
+		LOGP(DINP, LOGL_ERROR, "Extended protocol mismatch. We got 0x%x\n", iph_ext->proto);
+		goto err;
+	}
+
+	msg->l2h = iph_ext->data;
+
+	cmd = ctrl_cmd_parse(ccon, msg);
+
+	if (cmd) {
+		cmd->ccon = ccon;
+		if (ctrl_cmd_handle(cmd, ctrl->gsmnet) != CTRL_CMD_HANDLED) {
+			ctrl_cmd_send(queue, cmd);
+			talloc_free(cmd);
+		}
+	} else {
+		cmd = talloc_zero(ccon, struct ctrl_cmd);
+		if (!cmd)
+			goto err;
+		LOGP(DINP, LOGL_ERROR, "Command parser error.\n");
+		cmd->type = CTRL_TYPE_ERROR;
+		cmd->id = "err";
+		cmd->reply = "Command parser error.";
+		ctrl_cmd_send(queue, cmd);
+		talloc_free(cmd);
+	}
+
+	msgb_free(msg);
+	return 0;
+
+err:
+	control_close_conn(ccon);
+	msgb_free(msg);
+	return ret;
+}
+
+static int control_write_cb(struct osmo_fd *bfd, struct msgb *msg)
+{
+	int rc;
+
+	rc = write(bfd->fd, msg->data, msg->len);
+	if (rc != msg->len)
+		LOGP(DINP, LOGL_ERROR, "Failed to write message to the control connection.\n");
+
+	return rc;
+}
+
+static struct ctrl_connection *ctrl_connection_alloc(void *ctx)
+{
+	struct ctrl_connection *ccon = talloc_zero(ctx, struct ctrl_connection);
+	if (!ccon)
+		return NULL;
+
+	osmo_wqueue_init(&ccon->write_queue, 100);
+	/* Error handling here? */
+
+	INIT_LLIST_HEAD(&ccon->cmds);
+	return ccon;
+}
+
+static int listen_fd_cb(struct osmo_fd *listen_bfd, unsigned int what)
+{
+	int ret, fd, on;
+	struct ctrl_connection *ccon;
+	struct sockaddr_in sa;
+	socklen_t sa_len = sizeof(sa);
+
+
+	if (!(what & BSC_FD_READ))
+		return 0;
+
+	fd = accept(listen_bfd->fd, (struct sockaddr *) &sa, &sa_len);
+	if (fd < 0) {
+		perror("accept");
+		return fd;
+	}
+	LOGP(DINP, LOGL_INFO, "accept()ed new control connection from %s\n",
+		inet_ntoa(sa.sin_addr));
+
+	on = 1;
+	ret = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on));
+	if (ret != 0) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to set TCP_NODELAY: %s\n", strerror(errno));
+		close(fd);
+		return ret;
+	}
+	ccon = ctrl_connection_alloc(listen_bfd->data);
+	if (!ccon) {
+		LOGP(DINP, LOGL_ERROR, "Failed to allocate.\n");
+		close(fd);
+		return -1;
+	}
+
+	ccon->write_queue.bfd.data = listen_bfd->data;
+	ccon->write_queue.bfd.fd = fd;
+	ccon->write_queue.bfd.when = BSC_FD_READ;
+	ccon->write_queue.read_cb = handle_control_read;
+	ccon->write_queue.write_cb = control_write_cb;
+
+	ret = osmo_fd_register(&ccon->write_queue.bfd);
+	if (ret < 0) {
+		LOGP(DINP, LOGL_ERROR, "Could not register FD.\n");
+		close(ccon->write_queue.bfd.fd);
+		talloc_free(ccon);
+	}
+
+	return ret;
+}
+
+int controlif_setup(struct gsm_network *gsmnet, uint16_t port)
+{
+	int ret;
+	struct ctrl_handle *ctrl;
+
+	ctrl = talloc_zero(tall_bsc_ctx, struct ctrl_handle);
+	if (!ctrl)
+		return -ENOMEM;
+
+	ctrl->gsmnet = gsmnet;
+
+	ctrl_node_vec = vector_init(5);
+	if (!ctrl_node_vec)
+		return -ENOMEM;
+
+	/* Listen for control connections */
+	ret = make_sock(&ctrl->listen_fd, IPPROTO_TCP, 0, port,
+			0, listen_fd_cb, ctrl);
+	if (ret < 0) {
+		talloc_free(ctrl);
+		return ret;
+	}
+
+	return ret;
+}