Fix possible buffer overflows detected by newer GCC versions

GCC reports problems like this:

gcc -DHAVE_CONFIG_H -I. -I../include -I../include -Wall -Werror -I./include -D_FORTIFY_SOURCE=2 -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt -MT layer3/q931.lo -MD -MP -MF layer3/.deps/q931.Tpo -c layer3/q931.c  -fPIC -DPIC -o layer3/.libs/q931.o
In file included from /usr/include/string.h:494,
                 from layer3/q931.c:22:
In function ‘strncpy’,
    inlined from ‘mi_encode_redirecting_nr’ at layer3/q931.c:531:3:
/usr/include/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ forming offset [25, 31] is out of the bounds [0, 24] of object ‘ie’ with type ‘unsigned char[24]’ [-Werror=array-bounds]
   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Thanks to Tobias Powalowski for reporting this
This commit fixes issue #9 on github.

example/testcon.c

@@ -1309,7 +1309,7 @@ static int do_setup(devinfo_t *di) {
 
 int main(int argc, char *argv[])
 {
-	char FileName[200],FileNameOut[200], FileNameIn[200];
+	char FileName[200],FileNameOut[208], FileNameIn[208];
 	int aidx=1,para=1, idx;
 	char sw;
 	devinfo_t mISDN;
@@ -1373,7 +1373,7 @@ int main(int argc, char *argv[])
 			}  else {
 				if (para==1) {
 					if (argc > 1)
-						strncpy(FileName, argv[aidx], 199);
+						strncpy(FileName, argv[aidx], sizeof(FileName) - 1);
 					para++;
 				} else {
 					fprintf(stderr,"Undefined argument %s\n",argv[aidx]);
@@ -1391,8 +1391,8 @@ int main(int argc, char *argv[])
 		return 1;
 	}
 	close(err);
-	sprintf(FileNameOut,"%s.out", FileName);
-	sprintf(FileNameIn,"%s.in", FileName);
+	snprintf(FileNameOut, sizeof(FileNameOut) - 1, "%s.out", FileName);
+	snprintf(FileNameIn, sizeof(FileNameIn) - 1, "%s.in", FileName);
 	if (0>(mISDN.save = open(FileNameIn, O_WRONLY|O_CREAT|O_TRUNC,S_IRWXU))) {
 		printf("TestmISDN cannot open %s due to %s\n",FileNameIn,
 			strerror(errno));

lib/layer3/q931.c

@@ -506,7 +506,7 @@ mi_encode_called_nr(struct l3_msg *l3m, char *nr, unsigned int type, unsigned in
 int
 mi_encode_redirecting_nr(struct l3_msg *l3m, char *nr, int pres, unsigned int type, unsigned int plan, int reason)
 {
-	unsigned char ie[24];
+	unsigned char ie[32];
 	int l;
 
 	if (nr == NULL || *nr == 0) /* not provided */
@@ -537,7 +537,7 @@ mi_encode_redirecting_nr(struct l3_msg *l3m, char *nr, int pres, unsigned int ty
 int
 mi_encode_redirection_nr(struct l3_msg *l3m, char *nr, int pres, unsigned int type, unsigned int plan)
 {
-	unsigned char ie[24];
+	unsigned char ie[32];
 	int l;
 
 	if (nr == NULL || *nr == 0) /* not provided */

tools/logger_config_parser.l

@@ -460,9 +460,9 @@ static int setLayer3(int, int);
 						if (defController == currentController)
 							fprintf(stderr, "dumpfile ignored for global section\n");
 						else
-							strncpy(currentController->dumpfile, yytext, MAX_FILE_NAME);
+							strncpy(currentController->dumpfile, yytext, MAX_FILE_NAME - 1);
 					} else if (filetyp == 2) {
-						strncpy(currentController->logfile, yytext, MAX_FILE_NAME);
+						strncpy(currentController->logfile, yytext, MAX_FILE_NAME - 1);
 					} else {
 						fprintf(stderr, "Got unhandled filetype %d with %s  - abort\n", filetyp, yytext);
 						return -1;

tools/rename.c

@@ -88,7 +88,7 @@ int main(int argc, char *argv[])
 	}
 found_dev:
 	devname.id = i;
-	strncpy(devname.name, argv[2], MISDN_MAX_IDLEN);
+	strncpy(devname.name, argv[2], MISDN_MAX_IDLEN - 1);
 	ret = ioctl(sock, IMSETDEVNAME, &devname);
 	if (ret < 0) {
 		fprintf(stderr, "Cannot set device name for port %d: %s\n", i, strerror(errno));