http_parser: cast pointer arithmetic safely

deps/http-parser/http_parser.c

@@ -1992,6 +1992,9 @@ http_parse_host(const char * buf, struct http_parser_url *u, int found_at) {
   const char *p;
   size_t buflen = u->field_data[UF_HOST].off + u->field_data[UF_HOST].len;
 
+  if (buflen > UINT16_MAX)
+    return 1;
+
   u->field_data[UF_HOST].len = 0;
 
   s = found_at ? s_http_userinfo_start : s_http_host_start;
@@ -2006,21 +2009,21 @@ http_parse_host(const char * buf, struct http_parser_url *u, int found_at) {
     switch(new_s) {
       case s_http_host:
         if (s != s_http_host) {
-          u->field_data[UF_HOST].off = p - buf;
+          u->field_data[UF_HOST].off = (uint16_t)(p - buf);
         }
         u->field_data[UF_HOST].len++;
         break;
 
       case s_http_host_v6:
         if (s != s_http_host_v6) {
-          u->field_data[UF_HOST].off = p - buf;
+          u->field_data[UF_HOST].off = (uint16_t)(p - buf);
         }
         u->field_data[UF_HOST].len++;
         break;
 
       case s_http_host_port:
         if (s != s_http_host_port) {
-          u->field_data[UF_PORT].off = p - buf;
+          u->field_data[UF_PORT].off = (uint16_t)(p - buf);
           u->field_data[UF_PORT].len = 0;
           u->field_set |= (1 << UF_PORT);
         }
@@ -2029,7 +2032,7 @@ http_parse_host(const char * buf, struct http_parser_url *u, int found_at) {
 
       case s_http_userinfo:
         if (s != s_http_userinfo) {
-          u->field_data[UF_USERINFO].off = p - buf ;
+          u->field_data[UF_USERINFO].off = (uint16_t)(p - buf);
           u->field_data[UF_USERINFO].len = 0;
           u->field_set |= (1 << UF_USERINFO);
         }
@@ -2066,6 +2069,9 @@ http_parser_parse_url(const char *buf, size_t buflen, int is_connect,
   enum http_parser_url_fields uf, old_uf;
   int found_at = 0;
 
+  if (buflen > UINT16_MAX)
+    return 1;
+
   u->port = u->field_set = 0;
   s = is_connect ? s_req_server_start : s_req_spaces_before_url;
   uf = old_uf = UF_MAX;
@@ -2121,7 +2127,7 @@ http_parser_parse_url(const char *buf, size_t buflen, int is_connect,
       continue;
     }
 
-    u->field_data[uf].off = p - buf;
+    u->field_data[uf].off = (uint16_t)(p - buf);
     u->field_data[uf].len = 1;
 
     u->field_set |= (1 << uf);