w-h/0.2.0: Add an example of a file download

This also shows an example of (at least the best I could figure out) how
to send an error 4xx/5xx response back.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

1 files changed, 138 insertions, 0 deletions

diff --git a/c/wasi-http/0.2.0/download-test/component.c b/c/wasi-http/0.2.0/download-test/component.c
new file mode 100644
index 0000000..78981ed
--- /dev/null
+++ b/c/wasi-http/0.2.0/download-test/component.c
@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: Apache-2.0 */
+
+/*
+ * component.c - Example of writing a wasi-http Wasm component
+ *
+ * Copyright (C) Andrew Clayton
+ * Copyright (C) F5, Inc.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "proxy.h"
+
+#define IMG_SZ		(256 * 1024*1024UL)
+
+#define ex(...) \
+	do { \
+		printf(__VA_ARGS__); \
+		exit(EXIT_FAILURE); \
+	} while (0);
+
+void exports_wasi_http_incoming_handler_handle(
+	exports_wasi_http_incoming_handler_own_incoming_request_t request,
+	exports_wasi_http_incoming_handler_own_response_outparam_t response_out)
+{
+	int fd;
+	bool ok;
+	char clen[32];
+	char *buf;
+	wasi_http_types_own_outgoing_response_t resp;
+	wasi_http_types_borrow_outgoing_response_t b_resp;
+	wasi_http_types_own_fields_t fields;
+	wasi_http_types_borrow_fields_t b_fields;
+	wasi_http_types_result_own_outgoing_response_error_code_t rerr = { };
+	wasi_http_types_own_outgoing_body_t body;
+	wasi_http_types_borrow_outgoing_body_t b_body;
+	wasi_io_streams_own_output_stream_t out_stream;
+	wasi_io_streams_borrow_output_stream_t b_out_stream;
+	proxy_list_u8_t stream_data;
+	wasi_io_streams_stream_error_t stream_err;
+	wasi_http_types_header_error_t hdr_err;
+	wasi_http_types_field_key_t key;
+	wasi_http_types_field_value_t value;
+
+	(void)request;
+
+	buf = malloc(IMG_SZ);
+	fd = open("/var/tmp/img", O_RDONLY);
+	if (fd == -1) {
+		wasi_http_types_status_code_t sc;
+
+		printf("E: %s (/var/tmp/img)\n", strerror(errno));
+
+		switch (errno) {
+		case EACCES:
+		case EFAULT:
+		case EPERM:
+			sc = 403;
+			break;
+		case EBADF:
+		case ENAMETOOLONG:
+		case ENODEV:
+		case ENOENT:
+		case ENOTDIR:
+			sc = 404;
+			break;
+		default:
+			sc = 500;
+		}
+
+		fields = wasi_http_types_constructor_fields();
+		resp = wasi_http_types_constructor_outgoing_response(fields);
+		b_resp = wasi_http_types_borrow_outgoing_response(resp);
+		wasi_http_types_method_outgoing_response_set_status_code(b_resp,
+									 sc);
+		rerr.val.ok = resp;
+
+		goto out_response;
+	}
+
+	read(fd, buf, IMG_SZ);
+	close(fd);
+
+	fields = wasi_http_types_constructor_fields();
+	b_fields = wasi_http_types_borrow_fields(fields);
+
+	proxy_string_set((proxy_string_t *)&key, "Content-Type");
+	proxy_string_set((proxy_string_t *)&value, "application/octet-stream");
+
+	ok = wasi_http_types_method_fields_append(b_fields, &key, &value,
+						  &hdr_err);
+	if (!ok)
+		ex("wasi_http_types_method_fields_append(Content-Type) failed\n");
+
+	proxy_string_set((proxy_string_t *)&key, "Content-Length");
+	sprintf(clen, "%zu", IMG_SZ);
+	proxy_string_set((proxy_string_t *)&value, clen);
+
+	ok = wasi_http_types_method_fields_append(b_fields, &key, &value,
+						  &hdr_err);
+	if (!ok)
+		ex("wasi_http_types_method_fields_append(Content-Length) failed\n");
+
+	resp = wasi_http_types_constructor_outgoing_response(fields);
+	rerr.val.ok = resp;
+
+	b_resp = wasi_http_types_borrow_outgoing_response(resp);
+	ok = wasi_http_types_method_outgoing_response_body(b_resp, &body);
+	if (!ok)
+		ex("wasi_http_types_method_outgoing_response_body() failed\n");
+	b_body = wasi_http_types_borrow_outgoing_body(body);
+
+	ok = wasi_http_types_method_outgoing_body_write(b_body, &out_stream);
+	if (!ok)
+		ex("wasi_http_types_method_outgoing_body_write() failed\n");
+	b_out_stream = wasi_io_streams_borrow_output_stream(out_stream);
+
+	stream_data.len = IMG_SZ;
+	stream_data.ptr = (uint8_t *)buf;
+	ok = wasi_io_streams_method_output_stream_write(b_out_stream,
+							&stream_data,
+							&stream_err);
+	if (!ok)
+		ex("wasi_io_streams_method_output_stream_blocking_write_and_flush() failed\n");
+
+out_response:
+
+	wasi_http_types_static_response_outparam_set(response_out, &rerr);
+
+	free(buf);
+}