Rig out transport handling, finish identity reader

New patch will implement more transports, such as chunked and gzip.

cmd/http/main.ha

@@ -34,6 +34,6 @@ export fn main() void = {
 		log::printfln("{}: {}", name, val);
 	};
 
-	const body = resp.body as *http::reader;
+	const body = resp.body as *io::stream;
 	io::copy(os::stdout, body)!;
 };

net/http/do.ha

@@ -9,6 +9,7 @@ use net;
 use os;
 use strconv;
 use strings;
+use types;
 
 // Performs an HTTP [[request]] with the given [[client]]. The request is
 // performed synchronously; this function blocks until the server has returned
@@ -49,15 +50,28 @@ export fn do(client: *client, req: *request) (response | error) = {
 	read_statusline(&resp, &scan)?;
 	read_header(&resp.header, &scan)?;
 
-	const remain = bufio::scan_buffer(&scan);
-	const rd = alloc(reader {
-		vtable = &reader_vtable,
-		conn = conn,
-		...
-	});
-	rd.buffer[..len(remain)] = remain[..];
-	rd.pending = len(remain);
-	resp.body = rd;
+	const cl = header_get(&resp.header, "Content-Length");
+	const te = header_get(&resp.header, "Transfer-Encoding");
+	if (len(cl) > 1 || len(te) > 1) {
+		return protoerr;
+	};
+
+	if (len(te) == 1) {
+		abort(); // TODO: Assign transport encoding appropriately
+	} else {
+		let length = types::SIZE_MAX;
+		if (len(cl) == 1) {
+			length = match (strconv::stoz(cl[0])) {
+			case let z: size =>
+				yield z;
+			case =>
+				return protoerr;
+			};
+		};
+		const remain = bufio::scan_buffer(&scan);
+		resp.body = new_identity_reader(conn, remain, length);
+	};
+
 	return resp;
 };
 

net/http/header.ha

@@ -11,6 +11,7 @@ export type header = [](str, str);
 // Adds a given HTTP header, which may be added more than once. The name should
 // be canonicalized by the caller.
 export fn header_add(head: *header, name: str, val: str) void = {
+	assert(len(name) > 1 && len(val) > 1);
 	append(head, (strings::dup(name), strings::dup(val)));
 };
 
@@ -34,6 +35,18 @@ export fn header_del(head: *header, name: str) void = {
 	};
 };
 
+// Retrieves a value, or values, from a header. The empty slice indicates the
+// abscence of a header.
+export fn header_get(head: *header, name: str) []str = {
+	for (let i = 0z; i < len(head); i += 1) {
+		const (key, val) = head[i];
+		if (key == name) {
+			return [val];
+		};
+	};
+	return [];
+};
+
 // Frees state associated with an HTTP [[header]].
 export fn header_free(head: *header) void = {
 	for (let i = 0z; i < len(head); i += 1) {

net/http/response.ha

@@ -12,44 +12,12 @@ export type response = struct {
 	// The HTTP headers provided by the server.
 	header: header,
 	// The response body, if any.
-	body: nullable *reader,
+	body: nullable *io::stream,
 };
 
 // Frees state associated with an HTTP [[response]].
 export fn response_finish(resp: *response) void = {
 	header_free(&resp.header);
 	free(resp.reason);
-};
-
-export type reader = struct {
-	vtable: io::stream,
-	conn: io::handle,
-	buffer: [os::BUFSIZ]u8,
-	pending: size,
-};
-
-const reader_vtable = io::vtable {
-	reader = &reader_read,
-	...
-};
-
-fn reader_read(s: *io::stream, buf: []u8) (size | io::EOF | io::error) = {
-	let rd = s: *reader;
-	if (rd.pending == 0) {
-		match (io::read(rd.conn, rd.buffer)?) {
-		case let n: size =>
-			rd.pending = n;
-		case io::EOF =>
-			return io::EOF;
-		};
-	};
-
-	let n = len(buf);
-	if (n > rd.pending) {
-		n = rd.pending;
-	};
-	buf[..n] = rd.buffer[..n];
-	rd.buffer[..len(rd.buffer) - n] = rd.buffer[n..];
-	rd.pending -= n;
-	return n;
+	free(resp.body);
 };

net/http/transport.ha

@@ -0,0 +1,69 @@
+use io;
+use os;
+
+export type identity_reader = struct {
+	vtable: io::stream,
+	conn: io::handle,
+	buffer: [os::BUFSIZ]u8,
+	pending: size,
+	length: size,
+};
+
+const identity_reader_vtable = io::vtable {
+	reader = &identity_read,
+	...
+};
+
+// Creates a new reader that reads data until the response's Content-Length is
+// reached; i.e. the null Transport-Encoding.
+fn new_identity_reader(
+	conn: io::handle,
+	buffer: []u8,
+	content_length: size,
+) *io::stream = {
+	let rd = alloc(identity_reader {
+		vtable = &identity_reader_vtable,
+		conn = conn,
+		length = content_length,
+		...
+	});
+	rd.buffer[..len(buffer)] = buffer[..];
+	rd.pending = len(buffer);
+	return rd;
+};
+
+fn identity_read(
+	s: *io::stream,
+	buf: []u8,
+) (size | io::EOF | io::error) = {
+	let rd = s: *identity_reader;
+	assert(rd.vtable == &identity_reader_vtable);
+
+	if (rd.length <= 0) {
+		return io::EOF;
+	};
+
+	if (rd.pending == 0) {
+		let nread = rd.length;
+		if (nread > len(rd.buffer)) {
+			nread = len(rd.buffer);
+		};
+
+		match (io::read(rd.conn, rd.buffer[..nread])?) {
+		case let n: size =>
+			rd.pending = n;
+		case io::EOF =>
+			return io::EOF;
+		};
+	};
+
+	let n = len(buf);
+	if (n > rd.pending) {
+		n = rd.pending;
+	};
+	buf[..n] = rd.buffer[..n];
+	rd.buffer[..len(rd.buffer) - n] = rd.buffer[n..];
+	rd.pending -= n;
+	rd.length -= n;
+	return n;
+};