use url decode while handle file

Signed-off-by: Jianhui Zhao <zhaojh329@gmail.com>

src/file.c

@@ -38,6 +38,7 @@
 
 #include "uhttpd_internal.h"
 #include "mimetypes.h"
+#include "utils.h"
 #include "file.h"
 
 static const char *file_mktag(struct stat *s, char *buf, int len)
@@ -256,7 +257,8 @@ void serve_file(struct uh_connection *conn)
     struct uh_server_internal *srv = conni->srv;
     const char *docroot = srv->docroot;
     const char *index_page = srv->index_page;
-    static char fullpath[512];
+    static char fullpath[PATH_MAX];
+    int docroot_len;
     size_t start, end;
     const char *mime;
     struct stat st;
@@ -268,13 +270,16 @@ void serve_file(struct uh_connection *conn)
     if (!index_page || !index_page[0])
         index_page = "index.html";
 
-    strcpy(fullpath, docroot);
+    docroot_len = strlen(docroot);
+
+    memcpy(fullpath, docroot, docroot_len);
 
     if (!strncmp(path.p, "/", path.len)) {
-        strcat(fullpath, "/");
-        strcat(fullpath, index_page);
-    } else {
-        strncat(fullpath, path.p, path.len);
+        fullpath[docroot_len] = '/';
+        strcpy(fullpath + docroot_len + 1, index_page);
+    } else if (urldecode(fullpath + docroot_len, PATH_MAX - docroot_len, path.p, path.len) < 0) {
+        conn->error(conn, HTTP_STATUS_NOT_FOUND, NULL);
+        return;
     }
 
     if (stat(fullpath, &st) < 0) {

src/utils.c

@@ -28,6 +28,7 @@
 #include <arpa/inet.h>
 #include <netinet/in.h>
 #include <unistd.h>
+#include <ctype.h>
 
 #include "utils.h"
 
@@ -61,3 +62,30 @@ bool support_so_reuseport()
 
     return ok;
 }
+
+int urldecode(char *buf, int blen, const char *src, int slen)
+{
+    int i;
+    int len = 0;
+
+#define hex(x) \
+    (((x) <= '9') ? ((x) - '0') : \
+        (((x) <= 'F') ? ((x) - 'A' + 10) : \
+            ((x) - 'a' + 10)))
+
+    for (i = 0; (i < slen) && (len < blen); i++) {
+        if (src[i] != '%') {
+            buf[len++] = src[i];
+            continue;
+        }
+
+        if (i + 2 >= slen || !isxdigit(src[i + 1]) || !isxdigit(src[i + 2]))
+            return -2;
+
+        buf[len++] = (char)(16 * hex(src[i+1]) + hex(src[i+2]));
+        i += 2;
+    }
+    buf[len] = 0;
+
+    return (i == slen) ? len : -1;
+}

src/utils.h

@@ -42,4 +42,11 @@ const char *saddr2str(struct sockaddr *addr, char buf[], int len, int *port);
 
 bool support_so_reuseport();
 
+/*
+** blen is the size of buf; slen is the length of src.  The input-string need
+** not be, and the output string will not be, null-terminated.  Returns the
+** length of the decoded string, -1 on buffer overflow, -2 on malformed string.
+*/
+int urldecode(char *buf, int blen, const char *src, int slen);
+
 #endif