MINOR: quic: Variable-length integer encoding/decoding into/from buffer struct.
Add a function to encode a QUIC varint into a buffer struct. Samething for the
deconding part.
diff --git a/include/haproxy/xprt_quic.h b/include/haproxy/xprt_quic.h
index c2471cc..e3bef42 100644
--- a/include/haproxy/xprt_quic.h
+++ b/include/haproxy/xprt_quic.h
@@ -412,6 +412,46 @@
return 1;
}
+/* Decode a QUIC variable-length integer from <b> buffer into <val> supporting wrapping.
+ * Note that the result is a 64-bits integer but with the less significant
+ * 62 bits as relevant information. The most significant 2 bits encode
+ * the length of the integer.
+ * Note that this function update <b> buffer when a variable-length integer
+ * has successfully been parsed.
+ * Returns 1 and if succeeded (there was enough data in <buf>), 0 if not.
+ * If <retlen> is not null, increment <*retlen> by the number of bytes consumed to decode
+ * the varint.
+ */
+static inline size_t b_quic_dec_int(uint64_t *val, struct buffer *b, size_t *retlen)
+{
+ const unsigned char *pos = (const unsigned char *)b_head(b);
+ const unsigned char *end = (const unsigned char *)b_wrap(b);
+ size_t size = b_size(b);
+ size_t data = b_data(b);
+ size_t save_len, len;
+
+ if (!data)
+ return 0;
+
+ save_len = len = 1 << (*pos >> QUIC_VARINT_BYTE_0_SHIFT);
+ if (data < len)
+ return 0;
+
+ *val = *pos & QUIC_VARINT_BYTE_0_BITMASK;
+ if (++pos == end)
+ pos -= size;
+ while (--len) {
+ *val = (*val << 8) | *pos;
+ if (++pos == end)
+ pos -= size;
+ }
+ if (retlen)
+ *retlen += save_len;
+ b_del(b, save_len);
+
+ return 1;
+}
+
/* Encode a QUIC variable-length integer from <val> into <buf> buffer with <end> as first
* byte address after the end of this buffer.
* Returns 1 if succeeded (there was enough room in buf), 0 if not.
@@ -433,8 +473,45 @@
while (len--) {
*(*buf)++ = val >> shift;
shift -= 8;
+ }
+ *head |= size_bits;
+
+ return 1;
+}
+
+/* Encode a QUIC variable-length integer <val> into <b> buffer.
+ * Returns 1 if succeeded (there was enough room in buf), 0 if not.
+ */
+static inline int b_quic_enc_int(struct buffer *b, uint64_t val)
+{
+ unsigned int shift;
+ unsigned char size_bits, *head, *pos, *wrap;
+ size_t save_len, len;
+ size_t data = b_data(b);
+ size_t size = b_size(b);
+
+ if (data == size)
+ return 0;
+
+ save_len = len = quic_int_getsize(val);
+ if (!len)
+ return 0;
+
+ shift = (len - 1) * 8;
+ /* set the bits of byte#0 which gives the length of the encoded integer */
+ size_bits = quic_log2(len) << QUIC_VARINT_BYTE_0_SHIFT;
+ pos = head = (unsigned char *)b_head(b);
+ wrap = (unsigned char *)b_wrap(b);
+ while (len--) {
+ *pos++ = val >> shift;
+ shift -= 8;
+ if (pos == wrap)
+ pos -= size;
+ if (++data == size && len)
+ return 0;
}
*head |= size_bits;
+ b_add(b, save_len);
return 1;
}