MINOR: qpack: encode headers functions
diff --git a/src/qpack-enc.c b/src/qpack-enc.c
index c3983d4..f53de7c 100644
--- a/src/qpack-enc.c
+++ b/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;
+}