mctpd: Add toml-based configuration interface

This change adds a basic configuration interface, using a simple toml
syntax.

This allows configuration of the existing mctpd parameters: bus-owner
mode, the mctp timeout, and the UUID.

We ship a small example configuration under conf/.

Signed-off-by: Jeremy Kerr <[email protected]>

CHANGELOG.md

@@ -12,6 +12,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 2. mctpd: Allow recovery of devices reporting a nil UUID for development
 3. mctpd: Allow configuring .Connectivity as writable for development
 4. mctpd: Add AssignEndpointStatic for static EID allocations
+5. mctpd: Add a configuration file facility
 
 ### Changed
 

README.md

@@ -68,6 +68,9 @@ configured (ie., interfaces are enabled, and local addresses have been
 assigned). There are two sample systemd unit files under the conf/ directory, to
 coordinate the local setup and the supervision of the mctpd process.
 
+`mctpd` can read some basic configuration from a file, if the `-c FILE` argument
+is given. An example configuration is in [`conf/mctpd.conf`](conf/mctpd.conf).
+
 The `mctpd` daemon will expose a dbus interface, claiming the bus name
 `xyz.openbmc_project.MCTP` and object path `/xyz/openbmc_project/mctp`. This
 provides a few functions for configuring remote endpoints:

conf/mctpd.conf

@@ -0,0 +1,10 @@
+# Mode: either bus-owner or endpoint
+mode = "bus-owner"
+
+# MCTP protocol configuration. Used for both endpoint and bus-owner modes.
+[mctp]
+message_timeout_ms = 30
+
+# Specify a UUID: not generally required - mctpd will query the system UUID
+# where available.
+# uuid = "21f0f554-7f7c-4211-9ca1-6d0f000ea9e7"

meson.build

@@ -38,6 +38,11 @@ util_sources = ['src/mctp-util.c']
 netlink_sources = ['src/mctp-netlink.c']
 ops_sources = ['src/mctp-ops.c']
 
+toml_dep = declare_dependency(
+    sources: ['lib/tomlc99/toml.c'],
+    include_directories: include_directories('lib/tomlc99'),
+)
+
 executable('mctp',
     sources: ['src/mctp.c'] + netlink_sources + util_sources + ops_sources,
     install: true,
@@ -56,7 +61,7 @@ if libsystemd.found()
         sources: [
             'src/mctpd.c',
         ] + netlink_sources + util_sources + ops_sources,
-        dependencies: libsystemd,
+        dependencies: [libsystemd, toml_dep],
         install: true,
         install_dir: get_option('sbindir'),
     )
@@ -67,7 +72,7 @@ if libsystemd.found()
             'tests/mctp-ops-test.c',
         ] + netlink_sources + util_sources,
         include_directories:  include_directories('src'),
-        dependencies: libsystemd,
+        dependencies: [libsystemd, toml_dep],
     )
 endif
 

src/mctpd.c

@@ -29,6 +29,8 @@
 #include <systemd/sd-bus.h>
 #include <systemd/sd-id128.h>
 
+#include "toml.h"
+
 #include "mctp.h"
 #include "mctp-util.h"
 #include "mctp-netlink.h"
@@ -136,6 +138,10 @@ typedef struct peer peer;
 struct ctx {
 	sd_event *event;
 	sd_bus *bus;
+
+	// Configuration
+	const char *config_filename;
+
 	// Main instance for link/address state and listening for updates
 	mctp_nl *nl;
 
@@ -3534,9 +3540,10 @@ static int setup_testing(ctx *ctx) {
 
 static void print_usage(ctx *ctx)
 {
-	fprintf(stderr, "mctpd [-v] [-N]\n");
+	fprintf(stderr, "mctpd [-v] [-N] [-c FILE]\n");
 	fprintf(stderr, "      -v verbose\n");
 	fprintf(stderr, "      -N testing mode. Not safe for production\n");
+	fprintf(stderr, "      -c FILE read config from FILE\n");
 }
 
 static int parse_args(ctx *ctx, int argc, char **argv)
@@ -3545,12 +3552,13 @@ static int parse_args(ctx *ctx, int argc, char **argv)
 		{ .name = "help", .has_arg = no_argument, .val = 'h' },
 		{ .name = "verbose", .has_arg = no_argument, .val = 'v' },
 		{ .name = "testing", .has_arg = no_argument, .val = 'N' },
+		{ .name = "config", .has_arg = required_argument, .val = 'c' },
 		{ 0 },
 	};
 	int c;
 
 	for (;;) {
-		c = getopt_long(argc, argv, "+hvN", options, NULL);
+		c = getopt_long(argc, argv, "+hvNc:", options, NULL);
 		if (c == -1)
 			break;
 
@@ -3561,6 +3569,9 @@ static int parse_args(ctx *ctx, int argc, char **argv)
 		case 'v':
 			ctx->verbose = true;
 			break;
+		case 'c':
+			ctx->config_filename = strdup(optarg);
+			break;
 		case 'h':
 		default:
 			print_usage(ctx);
@@ -3570,6 +3581,20 @@ static int parse_args(ctx *ctx, int argc, char **argv)
 	return 0;
 }
 
+static int parse_config_mode(ctx *ctx, const char *mode)
+{
+	if (!strcmp(mode, "bus-owner")) {
+		ctx->bus_owner = true;
+	} else if (!strcmp(mode, "endpoint")) {
+		ctx->bus_owner = false;
+	} else {
+		warnx("invalid value '%s' for mode configuration", mode);
+		return -1;
+	}
+
+	return 0;
+}
+
 static int fill_uuid(ctx *ctx)
 {
 	int rc;
@@ -3594,16 +3619,91 @@ static int fill_uuid(ctx *ctx)
 	return rc;
 }
 
-static int setup_config(ctx *ctx)
+static int parse_config_mctp(ctx *ctx, toml_table_t *mctp_tab)
+{
+	toml_datum_t val;
+	int rc;
+
+	val = toml_int_in(mctp_tab, "message_timeout_ms");
+	if (val.ok) {
+		int64_t i = val.u.i;
+		if (i <= 0 || i > 100 * 1000) {
+			warnx("invalid message_timeout_ms value");
+			return -1;
+		}
+		ctx->mctp_timeout = i * 1000;
+	}
+
+	val = toml_string_in(mctp_tab, "uuid");
+	if (val.ok) {
+		rc = sd_id128_from_string(val.u.s, (void *)&ctx->uuid);
+		free(val.u.s);
+		if (rc) {
+			warnx("invalid UUID value");
+			return rc;
+		}
+	} else {
+		rc = fill_uuid(ctx);
+		if (rc)
+			return rc;
+	}
+
+	return 0;
+}
+
+static int parse_config(ctx *ctx)
 {
+	toml_table_t *conf_root, *mctp_tab;
+	char errbuf[256] = { 0 };
+	toml_datum_t val;
+	FILE *fp;
 	int rc;
-	// TODO: this will go in a config file or arguments.
+
+	if (!ctx->config_filename)
+		return 0;
+
+	rc = -1;
+	fp = fopen(ctx->config_filename, "r");
+	if (!fp) {
+		warn("can't open configuration file %s", ctx->config_filename);
+		return -1;
+	}
+
+	conf_root = toml_parse_file(fp, errbuf, sizeof(errbuf));
+	if (!conf_root) {
+		warnx("can't parse configuration file %s: %s",
+		      ctx->config_filename, errbuf);
+		goto out_close;
+	}
+
+	val = toml_string_in(conf_root, "mode");
+	if (val.ok) {
+		rc = parse_config_mode(ctx, val.u.s);
+		free(val.u.s);
+		if (rc)
+			goto out_free;
+	}
+
+	mctp_tab = toml_table_in(conf_root, "mctp");
+	if (mctp_tab) {
+		rc = parse_config_mctp(ctx, mctp_tab);
+		if (rc)
+			goto out_free;
+	}
+
+	rc = 0;
+
+out_free:
+	toml_free(conf_root);
+out_close:
+	fclose(fp);
+	return rc;
+}
+
+static void setup_config_defaults(ctx *ctx)
+{
 	ctx->mctp_timeout = 250000; // 250ms
 	ctx->bus_owner = true;
-	rc = fill_uuid(ctx);
-	if (rc < 0)
-		return rc;
-	return 0;
 }
 
 int main(int argc, char **argv)
@@ -3613,14 +3713,20 @@ int main(int argc, char **argv)
 
 	setlinebuf(stdout);
 
-	setup_config(ctx);
+	setup_config_defaults(ctx);
 	mctp_ops_init();
 
 	rc = parse_args(ctx, argc, argv);
 	if (rc != 0) {
 		return rc;
 	}
 
+	rc = parse_config(ctx);
+	if (rc) {
+		err(EXIT_FAILURE, "Can't load configuration file %s",
+		    ctx->config_filename);
+	}
+
 	ctx->nl = mctp_nl_new(false);
 	if (!ctx->nl) {
 		warnx("Failed creating netlink object");