altsvc: Add ALTSVC frame support

lib/includes/nghttp2/nghttp2.h

@@ -591,7 +591,11 @@ typedef enum {
    * callbacks because the library processes this frame type and its
    * preceding HEADERS/PUSH_PROMISE as a single frame.
    */
-  NGHTTP2_CONTINUATION = 0x09
+  NGHTTP2_CONTINUATION = 0x09,
+  /**
+   * The ALTSVC frame.
+   */
+  NGHTTP2_ALTSVC = 0x0a
 } nghttp2_frame_type;
 
 /**
@@ -4113,6 +4117,32 @@ NGHTTP2_EXTERN int nghttp2_submit_extension(nghttp2_session *session,
                                             uint8_t type, uint8_t flags,
                                             int32_t stream_id, void *payload);
 
+/**
+ * @struct
+ *
+ * The payload of ALTSVC frame.  ALTSVC frame is one of extension
+ * frame.  If this frame is received, and
+ * `nghttp2_option_set_user_recv_extension_type()` is not set, and
+ * `nghttp2_option_set_recv_extension_type()` is set for
+ * :enum:`NGHTTP2_ALTSVC`, ``nghttp2_extension.payload`` will point to
+ * this struct.
+ *
+ * It has the following members:
+ */
+typedef struct {
+  uint8_t *origin;
+  size_t origin_len;
+  uint8_t *field_value;
+  size_t field_value_len;
+} nghttp2_ext_altsvc;
+
+NGHTTP2_EXTERN int nghttp2_submit_altsvc(nghttp2_session *session,
+                                         uint8_t flags, int32_t stream_id,
+                                         const uint8_t *origin,
+                                         size_t origin_len,
+                                         const uint8_t *field_value,
+                                         size_t field_value_len);
+
 /**
  * @function
  *

lib/nghttp2_frame.c

@@ -193,6 +193,31 @@ void nghttp2_frame_extension_init(nghttp2_extension *frame, uint8_t type,
 
 void nghttp2_frame_extension_free(nghttp2_extension *frame _U_) {}
 
+void nghttp2_frame_altsvc_init(nghttp2_extension *frame, int32_t stream_id,
+                               uint8_t *origin, size_t origin_len,
+                               uint8_t *field_value, size_t field_value_len) {
+  nghttp2_ext_altsvc *altsvc;
+
+  nghttp2_frame_hd_init(&frame->hd, 2 + origin_len + field_value_len,
+                        NGHTTP2_ALTSVC, NGHTTP2_FLAG_NONE, stream_id);
+
+  altsvc = frame->payload;
+  altsvc->origin = origin;
+  altsvc->origin_len = origin_len;
+  altsvc->field_value = field_value;
+  altsvc->field_value_len = field_value_len;
+}
+
+void nghttp2_frame_altsvc_free(nghttp2_extension *frame, nghttp2_mem *mem) {
+  nghttp2_ext_altsvc *altsvc;
+
+  altsvc = frame->payload;
+  /* We use the same buffer for altsvc->origin and
+     altsvc->field_value. */
+  nghttp2_mem_free(mem, altsvc->origin);
+  nghttp2_mem_free(mem, altsvc);
+}
+
 size_t nghttp2_frame_priority_len(uint8_t flags) {
   if (flags & NGHTTP2_FLAG_PRIORITY) {
     return NGHTTP2_PRIORITY_SPECLEN;
@@ -668,6 +693,36 @@ void nghttp2_frame_unpack_window_update_payload(nghttp2_window_update *frame,
       nghttp2_get_uint32(payload) & NGHTTP2_WINDOW_SIZE_INCREMENT_MASK;
 }
 
+int nghttp2_frame_pack_altsvc(nghttp2_bufs *bufs, nghttp2_extension *frame) {
+  int rv;
+  nghttp2_buf *buf;
+  nghttp2_ext_altsvc *altsvc;
+
+  altsvc = frame->payload;
+
+  buf = &bufs->head->buf;
+
+  assert(nghttp2_buf_avail(buf) >=
+         2 + altsvc->origin_len + altsvc->field_value_len);
+
+  buf->pos -= NGHTTP2_FRAME_HDLEN;
+
+  nghttp2_frame_pack_frame_hd(buf->pos, &frame->hd);
+
+  nghttp2_put_uint16be(buf->last, (uint16_t)altsvc->origin_len);
+  buf->last += 2;
+
+  rv = nghttp2_bufs_add(bufs, altsvc->origin, altsvc->origin_len);
+
+  assert(rv == 0);
+
+  rv = nghttp2_bufs_add(bufs, altsvc->field_value, altsvc->field_value_len);
+
+  assert(rv == 0);
+
+  return 0;
+}
+
 nghttp2_settings_entry *nghttp2_frame_iv_copy(const nghttp2_settings_entry *iv,
                                               size_t niv, nghttp2_mem *mem) {
   nghttp2_settings_entry *iv_copy;

lib/nghttp2_frame.h

@@ -367,6 +367,17 @@ void nghttp2_frame_unpack_window_update_payload(nghttp2_window_update *frame,
                                                 const uint8_t *payload,
                                                 size_t payloadlen);
 
+/*
+ * Packs ALTSVC frame |frame| in wire frame format and store it in
+ * |bufs|.
+ *
+ * The caller must make sure that nghttp2_bufs_reset(bufs) is called
+ * before calling this function.
+ *
+ * This function always succeeds and returns 0.
+ */
+int nghttp2_frame_pack_altsvc(nghttp2_bufs *bufs, nghttp2_extension *ext);
+
 /*
  * Initializes HEADERS frame |frame| with given values.  |frame| takes
  * ownership of |nva|, so caller must not free it. If |stream_id| is
@@ -445,6 +456,12 @@ void nghttp2_frame_extension_init(nghttp2_extension *frame, uint8_t type,
 
 void nghttp2_frame_extension_free(nghttp2_extension *frame);
 
+void nghttp2_frame_altsvc_init(nghttp2_extension *frame, int32_t stream_id,
+                               uint8_t *origin, size_t origin_len,
+                               uint8_t *field_value, size_t field_value_len);
+
+void nghttp2_frame_altsvc_free(nghttp2_extension *frame, nghttp2_mem *mem);
+
 /*
  * Returns the number of padding bytes after payload.  The total
  * padding length is given in the |padlen|.  The returned value does

lib/nghttp2_outbound_item.c

@@ -72,9 +72,25 @@ void nghttp2_outbound_item_free(nghttp2_outbound_item *item, nghttp2_mem *mem) {
   case NGHTTP2_WINDOW_UPDATE:
     nghttp2_frame_window_update_free(&frame->window_update);
     break;
-  default:
-    nghttp2_frame_extension_free(&frame->ext);
-    break;
+  default: {
+    nghttp2_ext_aux_data *aux_data;
+
+    aux_data = &item->aux_data.ext;
+
+    if (aux_data->builtin == 0) {
+      nghttp2_frame_extension_free(&frame->ext);
+      break;
+    }
+
+    switch (frame->hd.type) {
+    case NGHTTP2_ALTSVC:
+      nghttp2_frame_altsvc_free(&frame->ext, mem);
+      break;
+    default:
+      assert(0);
+      break;
+    }
+  }
   }
 }
 

lib/nghttp2_outbound_item.h

@@ -87,11 +87,19 @@ typedef struct {
   uint8_t flags;
 } nghttp2_goaway_aux_data;
 
+/* struct used for extension frame */
+typedef struct {
+  /* nonzero if this extension frame is serialized by library
+     function, instead of user-defined callbacks. */
+  uint8_t builtin;
+} nghttp2_ext_aux_data;
+
 /* Additional data which cannot be stored in nghttp2_frame struct */
 typedef union {
   nghttp2_data_aux_data data;
   nghttp2_headers_aux_data headers;
   nghttp2_goaway_aux_data goaway;
+  nghttp2_ext_aux_data ext;
 } nghttp2_aux_data;
 
 struct nghttp2_outbound_item;

lib/nghttp2_session.c

@@ -1664,6 +1664,26 @@ static int session_predicate_window_update_send(nghttp2_session *session,
   return 0;
 }
 
+static int session_predicate_altsvc_send(nghttp2_session *session,
+                                         int32_t stream_id) {
+  nghttp2_stream *stream;
+
+  if (session_is_closing(session)) {
+    return NGHTTP2_ERR_SESSION_CLOSING;
+  }
+
+  if (stream_id == 0) {
+    return 0;
+  }
+
+  stream = nghttp2_session_get_stream(session, stream_id);
+  if (stream == NULL) {
+    return NGHTTP2_ERR_STREAM_CLOSED;
+  }
+
+  return 0;
+}
+
 /* Take into account settings max frame size and both connection-level
    flow control here */
 static ssize_t
@@ -2103,19 +2123,45 @@ static int session_prep_frame(nghttp2_session *session,
       /* We never handle CONTINUATION here. */
       assert(0);
       break;
-    default:
+    default: {
+      nghttp2_ext_aux_data *aux_data;
+
       /* extension frame */
-      if (session_is_closing(session)) {
-        return NGHTTP2_ERR_SESSION_CLOSING;
+
+      aux_data = &item->aux_data.ext;
+
+      if (aux_data->builtin == 0) {
+        if (session_is_closing(session)) {
+          return NGHTTP2_ERR_SESSION_CLOSING;
+        }
+
+        rv = session_pack_extension(session, &session->aob.framebufs, frame);
+        if (rv != 0) {
+          return rv;
+        }
+
+        break;
       }
 
-      rv = session_pack_extension(session, &session->aob.framebufs, frame);
-      if (rv != 0) {
-        return rv;
+      switch (frame->hd.type) {
+      case NGHTTP2_ALTSVC:
+        rv = session_predicate_altsvc_send(session, frame->hd.stream_id);
+        if (rv != 0) {
+          return rv;
+        }
+
+        nghttp2_frame_pack_altsvc(&session->aob.framebufs, &frame->ext);
+
+        break;
+      default:
+        /* Unreachable here */
+        assert(0);
+        break;
       }
 
       break;
     }
+    }
     return 0;
   } else {
     size_t next_readmax;

lib/nghttp2_submit.c

@@ -410,6 +410,78 @@ int nghttp2_submit_window_update(nghttp2_session *session, uint8_t flags,
   return 0;
 }
 
+int nghttp2_submit_altsvc(nghttp2_session *session, uint8_t flags _U_,
+                          int32_t stream_id, const uint8_t *origin,
+                          size_t origin_len, const uint8_t *field_value,
+                          size_t field_value_len) {
+  nghttp2_mem *mem;
+  uint8_t *buf, *p;
+  uint8_t *origin_copy;
+  uint8_t *field_value_copy;
+  nghttp2_outbound_item *item;
+  nghttp2_frame *frame;
+  nghttp2_ext_altsvc *altsvc;
+  int rv;
+
+  mem = &session->mem;
+
+  if (2 + origin_len + field_value_len > NGHTTP2_MAX_PAYLOADLEN) {
+    return NGHTTP2_ERR_INVALID_ARGUMENT;
+  }
+
+  buf = nghttp2_mem_malloc(mem, origin_len + field_value_len + 2);
+  if (buf == NULL) {
+    return NGHTTP2_ERR_NOMEM;
+  }
+
+  p = buf;
+
+  origin_copy = p;
+  p = nghttp2_cpymem(p, origin, origin_len);
+  *p++ = '\0';
+
+  field_value_copy = p;
+  p = nghttp2_cpymem(p, field_value, field_value_len);
+  *p++ = '\0';
+
+  item = nghttp2_mem_malloc(mem, sizeof(nghttp2_outbound_item));
+  if (item == NULL) {
+    rv = NGHTTP2_ERR_NOMEM;
+    goto fail_item_malloc;
+  }
+
+  nghttp2_outbound_item_init(item);
+
+  item->aux_data.ext.builtin = 1;
+
+  altsvc = nghttp2_mem_malloc(mem, sizeof(nghttp2_outbound_item));
+  if (item == NULL) {
+    rv = NGHTTP2_ERR_NOMEM;
+    goto fail_altsvc_malloc;
+  }
+
+  frame = &item->frame;
+  frame->ext.payload = altsvc;
+
+  nghttp2_frame_altsvc_init(&frame->ext, stream_id, origin_copy, origin_len,
+                            field_value_copy, field_value_len);
+
+  rv = nghttp2_session_add_item(session, item);
+  if (rv != 0) {
+    nghttp2_frame_altsvc_free(&frame->ext, mem);
+    nghttp2_mem_free(mem, item);
+  }
+
+  return 0;
+
+fail_altsvc_malloc:
+  free(item);
+fail_item_malloc:
+  free(buf);
+
+  return rv;
+}
+
 static uint8_t set_request_flags(const nghttp2_priority_spec *pri_spec,
                                  const nghttp2_data_provider *data_prd) {
   uint8_t flags = NGHTTP2_FLAG_NONE;