feat: honor the ABI version (#21)

src/http/ngx_http_wasm_ctx.h

@@ -6,9 +6,16 @@
 #include "ngx_http_wasm_state.h"
 
 
+#define PROXY_WASM_ABI_VER_010      0
+#define PROXY_WASM_ABI_VER_020      1
+#define PROXY_WASM_ABI_VER_021      2
+#define PROXY_WASM_ABI_VER_MAX      99
+
+
 typedef struct {
     void                  *plugin;
     uint32_t               cur_ctx_id;
+    uint32_t               abi_version;
     ngx_str_t              name;
     ngx_http_wasm_state_t *state;
     ngx_queue_t            occupied;

src/http/ngx_http_wasm_module.c

@@ -17,6 +17,12 @@ static bool     ngx_http_wasm_vm_inited = false;
 
 
 static ngx_str_t plugin_start = ngx_string("_start");
+static ngx_str_t abi_versions[] = {
+    ngx_string("proxy_abi_version_0_1_0"),
+    ngx_string("proxy_abi_version_0_2_0"),
+    ngx_string("proxy_abi_version_0_2_1"),
+    ngx_null_string,
+};
 static ngx_str_t proxy_on_context_create = ngx_string("proxy_on_context_create");
 static ngx_str_t proxy_on_configure = ngx_string("proxy_on_configure");
 static ngx_str_t proxy_on_done = ngx_string("proxy_on_done");
@@ -166,7 +172,8 @@ ngx_http_wasm_load_plugin(const char *name, size_t name_len,
                           const char *bytecode, size_t size)
 {
     void                    *plugin;
-    ngx_int_t                rc;
+    ngx_int_t                rc, i;
+    bool                     found;
     ngx_http_wasm_plugin_t  *hw_plugin;
 
     if (!ngx_http_wasm_vm_inited) {
@@ -195,6 +202,15 @@ ngx_http_wasm_load_plugin(const char *name, size_t name_len,
     hw_plugin->cur_ctx_id = 0;
     hw_plugin->plugin = plugin;
 
+    /* assumed using latest ABI by default */
+    hw_plugin->abi_version = PROXY_WASM_ABI_VER_MAX;
+    for (i = 0; abi_versions[i].len != 0; i++) {
+        found = ngx_wasm_vm.has(plugin, &abi_versions[i]);
+        if (found) {
+            hw_plugin->abi_version = i;
+        }
+    }
+
     hw_plugin->name.len = name_len;
     hw_plugin->name.data = (u_char *) (hw_plugin + 1);
     ngx_memcpy(hw_plugin->name.data, name, name_len);
@@ -591,10 +607,17 @@ ngx_http_wasm_on_http(ngx_http_wasm_plugin_ctx_t *hwp_ctx, ngx_http_request_t *r
         return NGX_DECLINED;
     }
 
-    rc = ngx_wasm_vm.call(hwp_ctx->hw_plugin->plugin,
-                          &proxy_on_request_headers,
-                          true, NGX_WASM_PARAM_I32_I32_I32, http_ctx->id,
-                          0, 1);
+    if (hwp_ctx->hw_plugin->abi_version == PROXY_WASM_ABI_VER_010) {
+        rc = ngx_wasm_vm.call(hwp_ctx->hw_plugin->plugin,
+                              &proxy_on_request_headers,
+                              true, NGX_WASM_PARAM_I32_I32, http_ctx->id, 0);
+    } else {
+        rc = ngx_wasm_vm.call(hwp_ctx->hw_plugin->plugin,
+                              &proxy_on_request_headers,
+                              true, NGX_WASM_PARAM_I32_I32_I32, http_ctx->id,
+                              0, 1);
+    }
+
     ngx_http_wasm_set_state(NULL);
 
     if (rc < 0) {

src/vm/vm.h

@@ -32,8 +32,15 @@ typedef struct {
      */
     int32_t          (*malloc)(ngx_log_t *log, int32_t size);
 
+    /*
+     * call run a function exported from the plugin.
+     */
     ngx_int_t        (*call)(void *plugin, ngx_str_t *name, bool has_result,
                              int param_type, ...);
+    /*
+     * has check if a function is exported from the plugin.
+     */
+    bool             (*has)(void *plugin, ngx_str_t *name);
 } ngx_wasm_vm_t;
 
 

src/vm/wasmtime.c

@@ -288,6 +288,17 @@ ngx_wasm_wasmtime_call(void *data, ngx_str_t *name, bool has_result, int param_t
 }
 
 
+static bool
+ngx_wasm_wasmtime_has(void *data, ngx_str_t *name)
+{
+    ngx_wasm_wasmtime_plugin_t *plugin = data;
+    wasmtime_extern_t           func;
+
+    return wasmtime_instance_export_get(plugin->context, &plugin->instance,
+                                        (const char *) name->data, name->len, &func);
+}
+
+
 u_char *
 ngx_wasm_wasmtime_get_memory(ngx_log_t *log, int32_t addr, int32_t size)
 {
@@ -349,4 +360,5 @@ ngx_wasm_vm_t ngx_wasm_vm = {
     ngx_wasm_wasmtime_get_memory,
     ngx_wasm_wasmtime_malloc,
     ngx_wasm_wasmtime_call,
+    ngx_wasm_wasmtime_has,
 };