improve check of cgi_dir request

main.c

@@ -9,7 +9,7 @@ main(int argc, char **argv)
 	char 		path[GEMINI_REQUEST_MAX]       = {'\0'};
 	char 		query[GEMINI_REQUEST_MAX]      = {'\0'};
 	char		cgi_dir[PATH_MAX]              = {'\0'};
-	char		rel_cgi_dir[PATH_MAX]     = {'\0'};
+	char		rel_cgi_dir[PATH_MAX]          = {'\0'};
 	char 		chroot_dir[PATH_MAX]           = DEFAULT_CHROOT;
 	char		tmp[PATH_MAX]                  = {'\0'};
 	int		option                         = 0;

tests/test.sh

@@ -80,23 +80,23 @@ OUT=$(printf "gemini://host.name/autoidx/\r\n" | ../vger -d var/gemini/ -i | tee
 if ! [ $OUT = "765bbbe2add810be8eb191bbde59e258" ] ; then echo "error" ; exit 1 ; fi
 
 # cgi simple script
-OUT=$(printf "gemini://host.name/cgi-bin/test.cgi\r\n" | ../vger -d var/gemini/ -c /cgi-bin | tee /dev/stderr | MD5)
+OUT=$(printf "gemini://host.name/cgi-bin/test.cgi\r\n" | ../vger -d var/gemini/ -c cgi-bin | tee /dev/stderr | MD5)
 if ! [ $OUT = "666e48200f90018b5e96c2cf974882dc" ] ; then echo "error" ; exit 1 ; fi
 
 # cgi with use of variables
-OUT=$(printf "gemini://host.name/cgi-bin/who.cgi?user=jean-mi\r\n" | ../vger -d var/gemini/ -c /cgi-bin | tee /dev/stderr | MD5)
+OUT=$(printf "gemini://host.name/cgi-bin/who.cgi?user=jean-mi\r\n" | ../vger -d var/gemini/ -c cgi-bin | tee /dev/stderr | MD5)
 if ! [ $OUT = "fa065a67d1f7c973501d4a9e3ca2ea57" ] ; then echo "error" ; exit 1 ; fi
 
 # cgi with error
-OUT=$(printf "gemini://host.name/cgi-bin/nope\r\n" | ../vger -d var/gemini/ -c /cgi-bin | tee /dev/stderr | MD5)
+OUT=$(printf "gemini://host.name/cgi-bin/nope\r\n" | ../vger -d var/gemini/ -c cgi-bin | tee /dev/stderr | MD5)
 if ! [ $OUT = "31b98e160402a073298c12f763d5db64" ] ; then echo "error" ; exit 1 ; fi
 
 # cgi with PATH_INFO
-OUT=$(printf "gemini://host.name/cgi-bin/test.cgi/path/info\r\n" | ../vger -d var/gemini -c /cgi-bin | tee /dev/stderr | MD5)
+OUT=$(printf "gemini://host.name/cgi-bin/test.cgi/path/info\r\n" | ../vger -d var/gemini -c cgi-bin | tee /dev/stderr | MD5)
 if ! [ $OUT = "ec64da76dc578ffb479fbfb23e3a7a5b" ] ; then echo "error" ; exit 1 ; fi
 
 # virtualhost + cgi
-OUT=$(printf "gemini://perso.pw/cgi-bin/test.cgi\r\n" | ../vger -v -d var/gemini/ -c /cgi-bin | tee /dev/stderr | MD5)
+OUT=$(printf "gemini://perso.pw/cgi-bin/test.cgi\r\n" | ../vger -v -d var/gemini/ -c cgi-bin | tee /dev/stderr | MD5)
 if ! [ $OUT = "666e48200f90018b5e96c2cf974882dc" ] ; then echo "error" ; exit 1 ; fi
 
 # percent-decoding

vger.c

@@ -214,18 +214,22 @@ int
 do_cgi(const char *rel_cgi_dir, const char *path, const char *hostname, const char *query)
 {
 
-	/* WARNING : this function is fragile since it
-	 * compares path using the string to access them.
-	 * It would be preferable to use stat() to check
-	 * if two path refer to the same inode
-	 */
+	struct stat	sbcgi	           = {0};
+	struct stat	sbpath	           = {0};
+	char 	        cgifp[PATH_MAX]	   = {'\0'}; /* cgi file to execute */
+	char 	        path_dir[PATH_MAX] = {'\0'};
+	char	        *path_info	   = NULL;
 
-	char cgifp[PATH_MAX] = {'\0'};		/* cgi file to execute */
-	char *path_info      = NULL;
+	/* get beginning of path */
+	/* path_dir is initialized so there is an \0 at the end */
+	memcpy(path_dir, path, strlen(rel_cgi_dir));
 
-	/* check if path starts with rel_cgi_dir */
-	if (strncmp(rel_cgi_dir, path, strlen(rel_cgi_dir)) != 0)
-		return 1; /* not in cgi_dir, go to display_file */
+	if (stat(rel_cgi_dir, &sbcgi) + stat(path_dir, &sbpath) != 0)
+		goto nocgi;
+
+	/* compare inodes */
+	if (sbcgi.st_ino != sbpath.st_ino)
+		goto nocgi; /* not in cgi_dir, go to display_file */
 
 	/* set env variables for CGI
 	 * see
@@ -251,7 +255,7 @@ do_cgi(const char *rel_cgi_dir, const char *path, const char *hostname, const ch
 	/* cgi file to execute */
 	esnprintf(cgifp, sizeof(cgifp), "%s", path + strlen(rel_cgi_dir) + 1);
 	if (!(*cgifp)) /* problem with cgi file, abort */
-		return 1;
+		goto nocgi;
 
 	/* check if there is something after cgi file for PATH_INFO */
 	path_info = strchr(cgifp, '/');
@@ -268,6 +272,9 @@ do_cgi(const char *rel_cgi_dir, const char *path, const char *hostname, const ch
 
 	cgi(cgifp);
 	return 0;
+
+nocgi:
+	return 1;
 }
 
 ssize_t