refactor(sys)!: remove foreign symbols from bindings

Leave only NGINX code and referenced types.

Author: bavshin-f5

examples/httporigdst.rs

@@ -1,16 +1,17 @@
 use std::ffi::{c_int, c_void};
 use std::ptr::addr_of;
 
+use libc::sockaddr_storage;
 use ngx::core;
 use ngx::ffi::{
     in_port_t, ngx_conf_t, ngx_connection_local_sockaddr, ngx_http_add_variable, ngx_http_module_t,
     ngx_http_variable_t, ngx_inet_get_port, ngx_int_t, ngx_module_t, ngx_sock_ntop, ngx_str_t,
-    ngx_variable_value_t, sockaddr, sockaddr_storage, INET_ADDRSTRLEN, NGX_HTTP_MODULE,
+    ngx_variable_value_t, sockaddr, NGX_HTTP_MODULE,
 };
 use ngx::http::{self, HttpModule};
 use ngx::{http_variable_get, ngx_log_debug_http, ngx_string};
 
-const IPV4_STRLEN: usize = INET_ADDRSTRLEN as usize;
+const IPV4_STRLEN: usize = 16; // Not exported from `libc`
 
 #[derive(Debug, Default)]
 struct NgxHttpOrigDstCtx {

nginx-sys/build/main.rs

@@ -215,10 +215,29 @@ fn generate_binding(nginx: &NginxSource) {
         .parse()
         .expect("rust-version is valid and supported by bindgen");
 
+    // Functions that we need for macro and inline fn reimplementations in the nginx-sys itself.
+    #[cfg(windows)]
+    let macro_dependencies = [
+        "GetLastError",
+        "SetLastError",
+        "SwitchToThread",
+        "WSAGetLastError",
+        "WSASetLastError",
+        "rand",
+    ];
+    #[cfg(not(windows))]
+    let macro_dependencies = ["random", "sched_yield", "usleep"];
+
     let bindings = bindgen::Builder::default()
-        // Bindings will not compile on Linux without block listing this item
-        // It is worth investigating why this is
-        .blocklist_item("IPPORT_RESERVED")
+        // Allow all the NGINX symbols,
+        .allowlist_function("ngx_.*")
+        .allowlist_type("ngx_.*")
+        .allowlist_var("(NGX|NGINX|ngx|nginx)_.*")
+        // ...and a few symbols required for compilation,
+        .allowlist_type("bpf_.*")
+        .allowlist_type("sig_atomic_t|time_t|u_char|u_short")
+        // ...and a couple of symbols we need in nginx-sys.
+        .allowlist_function(macro_dependencies.join("|"))
         // will be restored later in build.rs
         .blocklist_item("NGX_ALIGNMENT")
         .generate_cstr(true)