--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sip-in/readconf.c	Tue Sep 06 20:33:56 2022 -0800
@@ -0,0 +1,164 @@
+/*
+ * In this module we implement the reading of /var/gsm/themwi-sip-in.cfg:
+ * the main settings are bind-ip and bind-port, but we also have some
+ * optional config settings.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+
+struct in_addr sip_bind_ip;
+unsigned sip_bind_port;
+int cfg_use_100rel;
+
+static char config_file_pathname[] = "/var/gsm/themwi-sip-in.cfg";
+
+struct parse_state {
+	int lineno;
+	int set_mask;
+};
+
+static void
+handle_ip(st, kw, var, arg)
+	struct parse_state *st;
+	char *kw, *arg;
+	struct in_addr *var;
+{
+	var->s_addr = inet_addr(arg);
+	if (var->s_addr == INADDR_NONE) {
+		fprintf(stderr,
+			"%s line %d: invalid IP address argument \"%s\"\n",
+			config_file_pathname, st->lineno, arg);
+		exit(1);
+	}
+}
+
+static void
+handle_num(st, kw, var, arg)
+	struct parse_state *st;
+	char *kw, *arg;
+	unsigned *var;
+{
+	char *endp;
+
+	*var = strtoul(arg, &endp, 10);
+	if (*endp) {
+		fprintf(stderr, "%s line %d: invalid numeric argument \"%s\"\n",
+			config_file_pathname, st->lineno, arg);
+		exit(1);
+	}
+}
+
+static void
+handle_bool(st, kw, var, arg)
+	struct parse_state *st;
+	char *kw, *arg;
+	int *var;
+{
+	if (!strcmp(arg, "true") || !strcmp(arg, "on") || !strcmp(arg, "yes")
+	    || !strcmp(arg, "1")) {
+		*var = 1;
+		return;
+	}
+	if (!strcmp(arg, "false") || !strcmp(arg, "off") || !strcmp(arg, "no")
+	    || !strcmp(arg, "0")) {
+		*var = 0;
+		return;
+	}
+	fprintf(stderr, "%s line %d: invalid boolean argument \"%s\"\n",
+		config_file_pathname, st->lineno, arg);
+	exit(1);
+}
+
+static void
+process_line(st, line)
+	struct parse_state *st;
+	char *line;
+{
+	char *cp, *np, *arg;
+	void (*handler)(), *var;
+	int set_id;
+
+	if (!index(line, '\n')) {
+		fprintf(stderr, "%s line %d: too long or missing newline\n",
+			config_file_pathname, st->lineno);
+		exit(1);
+	}
+	for (cp = line; isspace(*cp); cp++)
+		;
+	if (*cp == '\0' || *cp == '#')
+		return;
+	for (np = cp; *cp && !isspace(*cp); cp++)
+		;
+	if (*cp)
+		*cp++ = '\0';
+	if (!strcmp(np, "bind-ip")) {
+		handler = handle_ip;
+		var = &sip_bind_ip;
+		set_id = 1;
+	} else if (!strcmp(np, "bind-port")) {
+		handler = handle_num;
+		var = &sip_bind_port;
+		set_id = 2;
+	} else if (!strcmp(np, "use-100rel")) {
+		handler = handle_bool;
+		var = &cfg_use_100rel;
+		set_id = 0;
+	} else {
+		fprintf(stderr, "%s line %d: non-understood keyword \"%s\"\n",
+			config_file_pathname, st->lineno, np);
+		exit(1);
+	}
+	if (st->set_mask & set_id) {
+		fprintf(stderr, "%s line %d: duplicate %s setting\n",
+			config_file_pathname, st->lineno, np);
+		exit(1);
+	}
+	while (isspace(*cp))
+		cp++;
+	if (*cp == '\0' || *cp == '#') {
+inv_syntax:	fprintf(stderr,
+			"%s line %d: %s setting requires one argument\n",
+			config_file_pathname, st->lineno, np);
+		exit(1);
+	}
+	for (arg = cp; *cp && !isspace(*cp); cp++)
+		;
+	if (*cp)
+		*cp++ = '\0';
+	while (isspace(*cp))
+		cp++;
+	if (*cp != '\0' && *cp != '#')
+		goto inv_syntax;
+	handler(st, np, var, arg);
+	st->set_mask |= set_id;
+}
+
+read_config_file()
+{
+	FILE *inf;
+	struct parse_state pst;
+	char linebuf[256];
+
+	inf = fopen(config_file_pathname, "r");
+	if (!inf) {
+		perror(config_file_pathname);
+		exit(1);
+	}
+	pst.set_mask = 0;
+	for (pst.lineno = 1; fgets(linebuf, sizeof linebuf, inf); pst.lineno++)
+		process_line(&pst, linebuf);
+	fclose(inf);
+	if (pst.set_mask != 3) {
+		fprintf(stderr, "error: %s did not set all required settings\n",
+			config_file_pathname);
+		exit(1);
+	}
+}