Can make new request with existing headers (#162)

Author: graebm

include/aws/http/request_response.h

@@ -419,6 +419,15 @@ void aws_http_headers_clear(struct aws_http_headers *headers);
 AWS_HTTP_API
 struct aws_http_message *aws_http_message_new_request(struct aws_allocator *allocator);
 
+/**
+ * Like aws_http_message_new_request(), but uses existing aws_http_headers instead of creating a new one.
+ * Acquires a hold on the headers, and releases it when the request is destroyed.
+ */
+AWS_HTTP_API
+struct aws_http_message *aws_http_message_new_request_with_headers(
+    struct aws_allocator *allocator,
+    struct aws_http_headers *existing_headers);
+
 /**
  * Create a new response message.
  * The message is blank, all properties (status, headers, etc) must be set individually.

source/request_response.c

@@ -367,7 +367,10 @@ static int s_set_string_from_cursor(
     *dst = new_str;
     return AWS_OP_SUCCESS;
 }
-static struct aws_http_message *s_message_new_common(struct aws_allocator *allocator) {
+static struct aws_http_message *s_message_new_common(
+    struct aws_allocator *allocator,
+    struct aws_http_headers *existing_headers) {
+
     struct aws_http_message *message = aws_mem_calloc(allocator, 1, sizeof(struct aws_http_message));
     if (!message) {
         goto error;
@@ -376,9 +379,14 @@ static struct aws_http_message *s_message_new_common(struct aws_allocator *alloc
     message->allocator = allocator;
     aws_atomic_init_int(&message->refcount, 1);
 
-    message->headers = aws_http_headers_new(allocator);
-    if (!message->headers) {
-        goto error;
+    if (existing_headers) {
+        message->headers = existing_headers;
+        aws_http_headers_acquire(message->headers);
+    } else {
+        message->headers = aws_http_headers_new(allocator);
+        if (!message->headers) {
+            goto error;
+        }
     }
 
     return message;
@@ -387,20 +395,36 @@ static struct aws_http_message *s_message_new_common(struct aws_allocator *alloc
     return NULL;
 }
 
-struct aws_http_message *aws_http_message_new_request(struct aws_allocator *allocator) {
-    AWS_PRECONDITION(allocator);
+static struct aws_http_message *s_message_new_request_common(
+    struct aws_allocator *allocator,
+    struct aws_http_headers *existing_headers) {
 
-    struct aws_http_message *message = s_message_new_common(allocator);
+    struct aws_http_message *message = s_message_new_common(allocator, existing_headers);
     if (message) {
         message->request_data = &message->subclass_data.request;
     }
     return message;
 }
 
+struct aws_http_message *aws_http_message_new_request_with_headers(
+    struct aws_allocator *allocator,
+    struct aws_http_headers *existing_headers) {
+
+    AWS_PRECONDITION(allocator);
+    AWS_PRECONDITION(existing_headers);
+
+    return s_message_new_request_common(allocator, existing_headers);
+}
+
+struct aws_http_message *aws_http_message_new_request(struct aws_allocator *allocator) {
+    AWS_PRECONDITION(allocator);
+    return s_message_new_request_common(allocator, NULL);
+}
+
 struct aws_http_message *aws_http_message_new_response(struct aws_allocator *allocator) {
     AWS_PRECONDITION(allocator);
 
-    struct aws_http_message *message = s_message_new_common(allocator);
+    struct aws_http_message *message = s_message_new_common(allocator, NULL);
     if (message) {
         message->response_data = &message->subclass_data.response;
         message->response_data->status = AWS_HTTP_STATUS_UNKNOWN;

tests/CMakeLists.txt

@@ -19,6 +19,7 @@ add_test_case(message_request_method)
 add_test_case(message_request_path)
 add_test_case(message_response_status)
 add_test_case(message_refcounts)
+add_test_case(message_with_existing_headers)
 add_test_case(message_handles_oom)
 
 add_test_case(h1_test_get_request)

tests/test_message.c

@@ -355,6 +355,28 @@ TEST_CASE(message_refcounts) {
     return AWS_OP_SUCCESS;
 }
 
+TEST_CASE(message_with_existing_headers) {
+    (void)ctx;
+    struct aws_http_headers *headers = aws_http_headers_new(allocator);
+    ASSERT_NOT_NULL(headers);
+
+    struct aws_http_message *message = aws_http_message_new_request_with_headers(allocator, headers);
+    ASSERT_NOT_NULL(message);
+
+    ASSERT_PTR_EQUALS(headers, aws_http_message_get_headers(message));
+
+    /* assert message has acquired hold on headers */
+    aws_http_headers_release(headers);
+
+    /* still valid, right? */
+    struct aws_http_header new_header = {aws_byte_cursor_from_c_str("Host"), aws_byte_cursor_from_c_str("example.com")};
+    ASSERT_SUCCESS(aws_http_message_add_header(message, new_header));
+
+    /* clean up*/
+    aws_http_message_release(message);
+    return AWS_OP_SUCCESS;
+}
+
 /* Do every operation that involves allocating some memory */
 int s_message_handles_oom_attempt(struct aws_http_message *request) {
     ASSERT_NOT_NULL(request);