[PATCH v4 09/14] efi_loader: net: add support to send http requests and parse http headers

[Adriano Cordova <adrianox@gmail.com>]

Add network-stack agnostic way to send an http request and
parse http headers from efi drivers. This uses wget as a
backend and communicates with it via efi_wget_info.

The function efi_net_do_request allocates a buffer on behalf of an
efi application using efi_alloc and passes it to wget to receive
the data. If the method is GET and the buffer is too small, it
re-allocates the buffer based on the last received Content-Length
header and tries again. If the method is HEAD it just issues one
request. So issuing a HEAD request (to update Content-Length) and
then a GET request is preferred but not required.

The function efi_net_parse_headers parses a raw buffer containing
an http header into an array of EFI specific 'http_header' structs.

Signed-off-by: Adriano Cordova <adrianox@gmail.com>
---

Changes in v4:
- Remove void* casts
- Add documentation

Changes in v3:
- Add a struct wget_http_info efi_wget_info for efi_net to pass to wget
  when issuing wget requests, instead of using the old wget_info (see v2
  of the series 'wget: Expose wget to applications').
- Let a pointer to the http status code be passed to efi_net_do_request
  for it to fill it for the client after a request.
 include/efi_loader.h     |  13 ++++
 lib/efi_loader/efi_net.c | 155 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 168 insertions(+)

diff --git a/include/efi_loader.h b/include/efi_loader.h
index f49f8e6be0..d96d4e08bd 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -16,6 +16,7 @@
 #include <image.h>
 #include <pe.h>
 #include <linux/list.h>
+#include <linux/sizes.h>
 #include <linux/oid_registry.h>
 
 struct blk_desc;
@@ -136,6 +137,18 @@ void efi_net_get_addr(struct efi_ipv4_address *ip,
 void efi_net_set_addr(struct efi_ipv4_address *ip,
 		      struct efi_ipv4_address *mask,
 		      struct efi_ipv4_address *gw);
+efi_status_t efi_net_do_request(u8 *url, enum efi_http_method method, void **buffer,
+				u32 *status_code, ulong *file_size, char *headers_buffer);
+#define MAX_HTTP_HEADERS_SIZE SZ_64K
+#define MAX_HTTP_HEADERS 100
+#define MAX_HTTP_HEADER_NAME 128
+#define MAX_HTTP_HEADER_VALUE 512
+struct http_header {
+	uchar name[MAX_HTTP_HEADER_NAME];
+	uchar value[MAX_HTTP_HEADER_VALUE];
+};
+
+void efi_net_parse_headers(ulong *num_headers, struct http_header *headers);
 #else
 static inline void efi_net_set_dp(const char *dev, const char *server) { }
 static inline void efi_net_get_dp(void **dp) { }
diff --git a/lib/efi_loader/efi_net.c b/lib/efi_loader/efi_net.c
index 2207caf6fe..d81277eb2e 100644
--- a/lib/efi_loader/efi_net.c
+++ b/lib/efi_loader/efi_net.c
@@ -17,6 +17,7 @@
 
 #include <efi_loader.h>
 #include <dm.h>
+#include <linux/sizes.h>
 #include <malloc.h>
 #include <vsprintf.h>
 #include <net.h>
@@ -34,6 +35,12 @@ static int rx_packet_num;
 static struct efi_net_obj *netobj;
 static struct efi_device_path *net_dp;
 
+static struct wget_http_info efi_wget_info = {
+	.set_bootdev = false,
+	.check_buffer_size = true,
+
+};
+
 /*
  * The notification function of this event is called in every timer cycle
  * to check if a new network packet has been received.
@@ -1158,3 +1165,151 @@ void efi_net_set_addr(struct efi_ipv4_address *ip,
 		memcpy(&net_netmask, mask, 4);
 #endif
 }
+
+/**
+ * efi_net_set_buffer() - allocate a buffer of min 64K
+ *
+ * @buffer:	allocated buffer
+ * @size:	desired buffer size
+ * Return:	status code
+ */
+static efi_status_t efi_net_set_buffer(void **buffer, size_t size)
+{
+	efi_status_t ret = EFI_SUCCESS;
+
+	if (size < SZ_64K)
+		size = SZ_64K;
+
+	efi_free_pool(*buffer);
+
+	*buffer = efi_alloc(size);
+	if (!*buffer)
+		ret = EFI_OUT_OF_RESOURCES;
+
+	efi_wget_info.buffer_size = (ulong)size;
+
+	return ret;
+}
+
+/**
+ * efi_net_parse_headers() - parse HTTP headers
+ *
+ * Parses the raw buffer efi_wget_info.headers into an array headers
+ * of efi structs http_headers. The array should be at least
+ * MAX_HTTP_HEADERS long.
+ *
+ * @num_headers:	number of headers
+ * @headers:		caller provided array of struct http_headers
+ */
+void efi_net_parse_headers(ulong *num_headers, struct http_header *headers)
+{
+	if (!num_headers || !headers)
+		return;
+
+	// Populate info with http headers.
+	*num_headers = 0;
+	const uchar *line_start = efi_wget_info.headers;
+	const uchar *line_end;
+	ulong count;
+	struct http_header *current_header;
+	const uchar *separator;
+	size_t name_length, value_length;
+
+	// Skip the first line (request or status line)
+	line_end = strstr(line_start, "\r\n");
+
+	if (line_end)
+		line_start = line_end + 2;
+
+	while ((line_end = strstr(line_start, "\r\n")) != NULL) {
+		count = *num_headers;
+		if (line_start == line_end || count >= MAX_HTTP_HEADERS)
+			break;
+		current_header = headers + count;
+		separator = strchr(line_start, ':');
+		if (separator) {
+			name_length = separator - line_start;
+			++separator;
+			while (*separator == ' ')
+				++separator;
+			value_length = line_end - separator;
+			if (name_length < MAX_HTTP_HEADER_NAME &&
+			    value_length < MAX_HTTP_HEADER_VALUE) {
+				strncpy(current_header->name, line_start, name_length);
+				current_header->name[name_length] = '\0';
+				strncpy(current_header->value, separator, value_length);
+				current_header->value[value_length] = '\0';
+				(*num_headers)++;
+			}
+		}
+		line_start = line_end + 2;
+	}
+}
+
+/**
+ * efi_net_do_request() - issue an HTTP request using wget
+ *
+ * @url:		url
+ * @method:		HTTP method
+ * @buffer:		data buffer
+ * @status_code:	HTTP status code
+ * @file_size:		file size in bytes
+ * @headers_buffer:	headers buffer
+ * Return:		status code
+ */
+efi_status_t efi_net_do_request(u8 *url, enum efi_http_method method, void **buffer,
+				u32 *status_code, ulong *file_size, char *headers_buffer)
+{
+	efi_status_t ret = EFI_SUCCESS;
+	int wget_ret;
+	static bool last_head;
+
+	if (!buffer || !file_size)
+		return EFI_ABORTED;
+
+	efi_wget_info.method = (enum wget_http_method)method;
+	efi_wget_info.headers = headers_buffer;
+
+	switch (method) {
+	case HTTP_METHOD_GET:
+		ret = efi_net_set_buffer(buffer, last_head ? (size_t)efi_wget_info.hdr_cont_len : 0);
+		if (ret != EFI_SUCCESS)
+			goto out;
+		wget_ret = wget_request((ulong)*buffer, url, &efi_wget_info);
+		if ((ulong)efi_wget_info.hdr_cont_len > efi_wget_info.buffer_size) {
+			// Try again with updated buffer size
+			ret = efi_net_set_buffer(buffer, (size_t)efi_wget_info.hdr_cont_len);
+			if (ret != EFI_SUCCESS)
+				goto out;
+			if (wget_request((ulong)*buffer, url, &efi_wget_info)) {
+				efi_free_pool(*buffer);
+				ret = EFI_DEVICE_ERROR;
+				goto out;
+			}
+		} else if (wget_ret) {
+			efi_free_pool(*buffer);
+			ret = EFI_DEVICE_ERROR;
+			goto out;
+		}
+		// Pass the actual number of received bytes to the application
+		*file_size = efi_wget_info.file_size;
+		*status_code = efi_wget_info.status_code;
+		last_head = false;
+		break;
+	case HTTP_METHOD_HEAD:
+		ret = efi_net_set_buffer(buffer, 0);
+		if (ret != EFI_SUCCESS)
+			goto out;
+		wget_request((ulong)*buffer, url, &efi_wget_info);
+		*file_size = 0;
+		*status_code = efi_wget_info.status_code;
+		last_head = true;
+		break;
+	default:
+		ret = EFI_UNSUPPORTED;
+		break;
+	}
+
+out:
+	return ret;
+}
-- 
2.43.0