1 files changed, 122 insertions, 0 deletions
diff --git a/lib/nghttp3_qpack_huffman.c b/lib/nghttp3_qpack_huffman.c
new file mode 100644
index 0000000..c36a68e
--- /dev/null
+++ b/lib/nghttp3_qpack_huffman.c
@@ -0,0 +1,122 @@
+/*
+ * nghttp3
+ *
+ * Copyright (c) 2019 nghttp3 contributors
+ * Copyright (c) 2013 nghttp2 contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include "nghttp3_qpack_huffman.h"
+
+#include <string.h>
+#include <assert.h>
+#include <stdio.h>
+
+#include "nghttp3_conv.h"
+
+size_t nghttp3_qpack_huffman_encode_count(const uint8_t *src, size_t len) {
+  size_t i;
+  size_t nbits = 0;
+
+  for (i = 0; i < len; ++i) {
+    nbits += huffman_sym_table[src[i]].nbits;
+  }
+  /* pad the prefix of EOS (256) */
+  return (nbits + 7) / 8;
+}
+
+uint8_t *nghttp3_qpack_huffman_encode(uint8_t *dest, const uint8_t *src,
+                                      size_t srclen) {
+  const nghttp3_qpack_huffman_sym *sym;
+  const uint8_t *end = src + srclen;
+  uint64_t code = 0;
+  size_t nbits = 0;
+  uint32_t x;
+
+  for (; src != end;) {
+    sym = &huffman_sym_table[*src++];
+    code |= (uint64_t)sym->code << (32 - nbits);
+    nbits += sym->nbits;
+    if (nbits < 32) {
+      continue;
+    }
+    x = htonl((uint32_t)(code >> 32));
+    memcpy(dest, &x, 4);
+    dest += 4;
+    code <<= 32;
+    nbits -= 32;
+  }
+
+  for (; nbits >= 8;) {
+    *dest++ = (uint8_t)(code >> 56);
+    code <<= 8;
+    nbits -= 8;
+  }
+
+  if (nbits) {
+    *dest++ = (uint8_t)((uint8_t)(code >> 56) | ((1 << (8 - nbits)) - 1));
+  }
+
+  return dest;
+}
+
+void nghttp3_qpack_huffman_decode_context_init(
+    nghttp3_qpack_huffman_decode_context *ctx) {
+  ctx->fstate = NGHTTP3_QPACK_HUFFMAN_ACCEPTED;
+}
+
+nghttp3_ssize
+nghttp3_qpack_huffman_decode(nghttp3_qpack_huffman_decode_context *ctx,
+                             uint8_t *dest, const uint8_t *src, size_t srclen,
+                             int fin) {
+  uint8_t *p = dest;
+  const uint8_t *end = src + srclen;
+  nghttp3_qpack_huffman_decode_node node = {ctx->fstate, 0};
+  const nghttp3_qpack_huffman_decode_node *t = &node;
+  uint8_t c;
+
+  /* We use the decoding algorithm described in
+     http://graphics.ics.uci.edu/pub/Prefix.pdf */
+  for (; src != end;) {
+    c = *src++;
+    t = &qpack_huffman_decode_table[t->fstate & 0x1ff][c >> 4];
+    if (t->fstate & NGHTTP3_QPACK_HUFFMAN_SYM) {
+      *p++ = t->sym;
+    }
+
+    t = &qpack_huffman_decode_table[t->fstate & 0x1ff][c & 0xf];
+    if (t->fstate & NGHTTP3_QPACK_HUFFMAN_SYM) {
+      *p++ = t->sym;
+    }
+  }
+
+  ctx->fstate = t->fstate;
+
+  if (fin && !(ctx->fstate & NGHTTP3_QPACK_HUFFMAN_ACCEPTED)) {
+    return NGHTTP3_ERR_QPACK_FATAL;
+  }
+
+  return p - dest;
+}
+
+int nghttp3_qpack_huffman_decode_failure_state(
+    nghttp3_qpack_huffman_decode_context *ctx) {
+  return ctx->fstate == 0x100;
+}