MINOR: qpack: encode headers functions

include/haproxy/qpack-enc.h

@@ -1,4 +1,12 @@
 #ifndef QPACK_ENC_H_
 #define QPACK_ENC_H_
 
+#include <haproxy/istbuf.h>
+
+struct buffer;
+
+int qpack_encode_field_section_line(struct buffer *out);
+int qpack_encode_int_status(struct buffer *out, unsigned int status);
+int qpack_encode_header(struct buffer *out, const struct ist n, const struct ist v);
+
 #endif /* QPACK_ENC_H_ */

src/qpack-enc.c

@@ -1 +1,136 @@
 #include <haproxy/qpack-enc.h>
+
+#include <haproxy/buf.h>
+#include <haproxy/intops.h>
+
+/* Returns the byte size required to encode <i> as a <prefix_size>-prefix
+ * integer.
+ */
+static size_t qpack_get_prefix_int_size(int i, int prefix_size)
+{
+	int n = (1 << prefix_size) - 1;
+	if (i < n) {
+		return 1;
+	}
+	else {
+		size_t result = 0;
+		while (i) {
+			++result;
+			i >>= 7;
+		}
+		return 1 + result;
+	}
+}
+
+/* Encode the integer <i> in the buffer <out> in a <prefix_size>-bit prefix
+ * integer. The caller must ensure there is enough size in the buffer. The
+ * prefix is OR-ed with <before_prefix> byte.
+ *
+ * Returns 0 if success else non-zero.
+ */
+static int qpack_encode_prefix_integer(struct buffer *out, int i, int prefix_size, unsigned char before_prefix)
+{
+	BUG_ON(!prefix_size);
+
+	if (i < (1 << prefix_size) - 1) {
+		if (b_data(out) < 1)
+			return 1;
+
+		b_putchr(out, before_prefix | i);
+	}
+	else {
+		if (b_data(out) < 2)
+			return 1;
+
+		b_putchr(out, before_prefix | ((1 << prefix_size) - 1));
+		b_putchr(out, i - ((1 << prefix_size) - 1));
+	}
+
+	return 0;
+}
+
+/* Returns 0 on success else non-zero. */
+int qpack_encode_int_status(struct buffer *out, unsigned int status)
+{
+	int status_size, idx = 0;
+
+	switch (status) {
+	case 103: idx = 24; break;
+	case 200: idx = 25; break;
+	case 304: idx = 26; break;
+	case 404: idx = 27; break;
+	case 503: idx = 28; break;
+	case 100: idx = 63; break;
+	case 204: idx = 64; break;
+	case 206: idx = 65; break;
+	case 302: idx = 66; break;
+	case 400: idx = 67; break;
+	case 403: idx = 68; break;
+	case 421: idx = 69; break;
+	case 425: idx = 70; break;
+	case 500: idx = 71; break;
+
+	default:
+		BUG_ON(1);
+		break;
+	}
+
+	status_size = qpack_get_prefix_int_size(idx, 6);
+	if (b_room(out) < status_size)
+		return 1;
+
+	//b_quic_enc_int(out, idx);
+	qpack_encode_prefix_integer(out, idx, 6, 0xc0);
+	return 0;
+}
+
+/* Returns 0 on success else non-zero. */
+int qpack_encode_field_section_line(struct buffer *out)
+{
+	if (b_room(out) < 2)
+		return 1;
+
+	char qpack_field_section[] = {
+	  '\x00',   /* required insert count */
+	  '\x00',   /* S + delta base */
+	};
+	b_putblk(out, qpack_field_section, 2);
+
+	return 0;
+}
+
+#define QPACK_LFL_WLN_BIT  0x20 // Literal field line with literal name
+
+/* Encode a header in literal field line with literal name.
+ * Returns 0 on success else non-zero.
+ */
+int qpack_encode_header(struct buffer *out, const struct ist n, const struct ist v)
+{
+	int i;
+	size_t sz = qpack_get_prefix_int_size(n.len, 3) + n.len +
+	            qpack_get_prefix_int_size(v.len, 7) + v.len;
+
+	if (sz > b_room(out))
+		return 1;
+
+	/* literal field line with literal name
+	 * | 0 | 0 | 1 | N | H | . | . | . |
+	 * N :(allow an intermediary to add the header in a dynamic table)
+	 * H: huffman encoded
+	 * name len
+	 */
+	qpack_encode_prefix_integer(out, n.len, 3, QPACK_LFL_WLN_BIT);
+	/* name */
+	for (i = 0; i < n.len; ++i)
+		b_putchr(out, n.ptr[i]);
+
+	/* | 0 | . | . | . | . | . | . | . |
+	 * value len
+	 */
+	qpack_encode_prefix_integer(out, v.len, 7, 0x00);
+	/* value */
+	for (i = 0; i < v.len; ++i)
+		b_putchr(out, v.ptr[i]);
+
+	return 0;
+}