crypto: have fixed NodeBIOs return EOF.

src/node_crypto.cc

@@ -416,29 +416,18 @@ void SecureContext::Init(const FunctionCallbackInfo<Value>& args) {
 // Takes a string or buffer and loads it into a BIO.
 // Caller responsible for BIO_free_all-ing the returned object.
 static BIO* LoadBIO(Environment* env, Local<Value> v) {
-  BIO* bio = NodeBIO::New();
-  if (!bio)
-    return nullptr;
-
   HandleScope scope(env->isolate());
 
-  int r = -1;
-
   if (v->IsString()) {
     const node::Utf8Value s(env->isolate(), v);
-    r = BIO_write(bio, *s, s.length());
-  } else if (Buffer::HasInstance(v)) {
-    char* buffer_data = Buffer::Data(v);
-    size_t buffer_length = Buffer::Length(v);
-    r = BIO_write(bio, buffer_data, buffer_length);
+    return NodeBIO::NewFixed(*s, s.length());
   }
 
-  if (r <= 0) {
-    BIO_free_all(bio);
-    return nullptr;
+  if (Buffer::HasInstance(v)) {
+    return NodeBIO::NewFixed(Buffer::Data(v), Buffer::Length(v));
   }
 
-  return bio;
+  return nullptr;
 }
 
 
@@ -761,15 +750,12 @@ void SecureContext::AddRootCerts(const FunctionCallbackInfo<Value>& args) {
     root_cert_store = X509_STORE_new();
 
     for (size_t i = 0; i < ARRAY_SIZE(root_certs); i++) {
-      BIO* bp = NodeBIO::New();
-
-      if (!BIO_write(bp, root_certs[i], strlen(root_certs[i]))) {
-        BIO_free_all(bp);
+      BIO* bp = NodeBIO::NewFixed(root_certs[i], strlen(root_certs[i]));
+      if (bp == nullptr) {
         return;
       }
 
       X509 *x509 = PEM_read_bio_X509(bp, nullptr, CryptoPemCallback, nullptr);
-
       if (x509 == nullptr) {
         BIO_free_all(bp);
         return;

src/node_crypto_bio.cc

@@ -2,6 +2,7 @@
 #include "openssl/bio.h"
 #include "util.h"
 #include "util-inl.h"
+#include <limits.h>
 #include <string.h>
 
 namespace node {
@@ -27,6 +28,21 @@ BIO* NodeBIO::New() {
 }
 
 
+BIO* NodeBIO::NewFixed(const char* data, size_t len) {
+  BIO* bio = New();
+
+  if (bio == nullptr ||
+      len > INT_MAX ||
+      BIO_write(bio, data, len) != static_cast<int>(len) ||
+      BIO_set_mem_eof_return(bio, 0) != 1) {
+    BIO_free(bio);
+    return nullptr;
+  }
+
+  return bio;
+}
+
+
 void NodeBIO::AssignEnvironment(Environment* env) {
   env_ = env;
 }

src/node_crypto_bio.h

@@ -23,6 +23,10 @@ class NodeBIO {
 
   static BIO* New();
 
+  // NewFixed takes a copy of `len` bytes from `data` and returns a BIO that,
+  // when read from, returns those bytes followed by EOF.
+  static BIO* NewFixed(const char* data, size_t len);
+
   void AssignEnvironment(Environment* env);
 
   // Move read head to next buffer if needed