feat(lander): implement placeholder keys

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://git.rustybever.be/Chewing_Bever/lander/src/branch/dev)
 
+## Added
+
+* Ability to generate keys that allow one-time unauthenticated uploads (a.k.a.
+  generating upload links)
+
 ## Fixed
 
 * Failed uploads now no longer leave behind a partial entry file

include/lander.h

@@ -27,6 +27,7 @@ typedef enum lander_entry_type : uint8_t {
   lander_entry_type_redirect = 0,
   lander_entry_type_paste = 1,
   lander_entry_type_file = 2,
+  lander_entry_type_placeholder = 3,
 } lander_entry_type;
 
 void *lander_gctx_init();
@@ -61,6 +62,16 @@ lnm_http_step_err lander_post_file(lnm_http_conn *conn);
 
 lnm_http_step_err lander_post_file_secure(lnm_http_conn *conn);
 
+lnm_http_step_err lander_post_placeholder(lnm_http_conn *conn);
+
+lnm_http_step_err lander_post_placeholder_secure(lnm_http_conn *conn);
+
+/**
+ * Step that authenticates requests. If the key of the request is for a
+ * placeholder entry, authentication is granted without an api key.
+ */
+lnm_http_step_err lander_auth_or_placeholder(lnm_http_conn *conn);
+
 /**
  * Store the requested header as an attribute, if it's present.
  */

lsm/include/lsm/store.h

@@ -56,7 +56,8 @@ lsm_error lsm_entry_attr_get_uint8_t(uint8_t *out, lsm_entry_handle *handle,
                                      uint8_t type);
 
 /**
- * Add a new attribute to the entry.
+ * Add a new attribute to the entry. This overwrites an existing version of this
+ * attribute.
  *
  * @param entry entry to modify
  * @param type type of attribute to add

lsm/src/store/lsm_store_disk_write.c

@@ -1,3 +1,5 @@
+#include <stdint.h>
+
 #include "lsm/store_internal.h"
 
 static lsm_error lsm_fwrite(uint64_t *sum, FILE *f, uint64_t size,
@@ -125,16 +127,10 @@ lsm_error lsm_entry_disk_insert(lsm_entry_handle *handle) {
   return res;
 }
 
-// Marking an entry as removed in the idx file is simply setting the length of
-// its entry to zero
-lsm_error lsm_entry_disk_remove(lsm_entry_handle *handle) {
-  lsm_store *store = handle->store;
-  const lsm_entry *entry = handle->wrapper->entry;
-
+static lsm_error lsm_idx_zero_block(lsm_store *store, uint64_t pos) {
   pthread_mutex_lock(&store->idx.lock);
 
-  lsm_error res =
-      lsm_fseek(store->idx.f, entry->idx_file_offset + sizeof(uint64_t));
+  lsm_error res = lsm_fseek(store->idx.f, pos);
 
   if (res != lsm_error_ok) {
     pthread_mutex_unlock(&store->idx.lock);
@@ -153,7 +149,29 @@ lsm_error lsm_entry_disk_remove(lsm_entry_handle *handle) {
 
   fflush(store->idx.f);
 
+  return lsm_error_ok;
+}
+
+// Marking an entry as removed in the idx file is simply setting the length of
+// its entry to zero
+lsm_error lsm_entry_disk_remove(lsm_entry_handle *handle) {
+  const lsm_entry *entry = handle->wrapper->entry;
+
+  LSM_RES(lsm_idx_zero_block(handle->store,
+                             entry->idx_file_offset + sizeof(uint64_t)));
   LSM_RES(lsm_entry_data_remove(handle));
 
   return lsm_error_ok;
 }
+
+lsm_error lsm_entry_disk_update(lsm_entry_handle *handle) {
+  // An update is implemented by reinserting the entry at the end of the db file
+  uint64_t old_idx_index = handle->wrapper->entry->idx_file_offset;
+
+  // TODO is there any way we can make this atomic? If the zero write to the
+  // index file fails, there are two entries in the db file for the same key.
+  LSM_RES(lsm_entry_disk_insert(handle));
+  LSM_RES(lsm_idx_zero_block(handle->store, old_idx_index + sizeof(uint64_t)));
+
+  return lsm_error_ok;
+}

lsm/src/store/lsm_store_entry.c

@@ -61,6 +61,7 @@ lsm_error lsm_entry_handle_init(lsm_entry_handle **out) {
 lsm_error lsm_entry_commit(lsm_entry_handle *handle) {
   uint8_t state_new = handle->states & lsm_entry_handle_state_new;
   uint8_t state_removed = handle->states & lsm_entry_handle_state_removed;
+  uint8_t state_updated = handle->states & lsm_entry_handle_state_updated;
 
   // Clean new entry
   if (state_new && !state_removed) {
@@ -73,6 +74,8 @@ lsm_error lsm_entry_commit(lsm_entry_handle *handle) {
 
     lsm_entry_free(handle->wrapper->entry);
     handle->wrapper->entry = NULL;
+  } else if (state_updated && !(state_new || state_removed)) {
+    LSM_RES(lsm_entry_disk_update(handle));
   }
 
   // Reset states after committing current changes
@@ -99,6 +102,8 @@ void lsm_entry_close(lsm_entry_handle *handle) {
     handle->wrapper->entry = NULL;
   }
 
+  // TODO rollback uncomitted updates
+
   pthread_rwlock_unlock(&handle->wrapper->lock);
   free(handle);
 }
@@ -206,8 +211,10 @@ lsm_error lsm_entry_attr_remove(lsm_str **out, lsm_entry_handle *handle,
 
 lsm_error lsm_entry_attr_insert(lsm_entry_handle *handle, uint8_t type,
                                 lsm_str *data) {
-  if (lsm_entry_attr_present(handle, type)) {
-    return lsm_error_already_present;
+  // Remove a previous version of the attribute
+  lsm_str *out;
+  if (lsm_entry_attr_remove(&out, handle, type) == lsm_error_ok) {
+    lsm_str_free(out);
   }
 
   lsm_entry *entry = handle->wrapper->entry;

src/lander/lander_post.c

@@ -17,7 +17,8 @@ static void randomize_key(char *key, int len) {
 }
 
 /**
- * Insert a new entry into the store.
+ * Insert a new entry into the store. If an entry is already open, this function
+ * is a no-op.
  *
  * @return true on success, false otherwise
  */
@@ -26,6 +27,12 @@ bool lander_insert_entry(lnm_http_loop_ctx *ctx, bool secure) {
   lander_gctx *c_gctx = gctx->c;
   lander_ctx *c_ctx = ctx->c;
 
+  // With placeholders, the entry will already be open so an entry should no
+  // longer be created
+  if (c_ctx->entry != NULL) {
+    return true;
+  }
+
   const char *key_s;
   size_t key_len = lnm_http_req_route_segment(&key_s, &ctx->req, "key");
 
@@ -147,3 +154,25 @@ lnm_http_step_err lander_post_file(lnm_http_conn *conn) {
 lnm_http_step_err lander_post_file_secure(lnm_http_conn *conn) {
   return __lander_post_file(conn, true);
 }
+
+lnm_http_step_err __lander_post_placeholder(lnm_http_conn *conn, bool secure) {
+  lnm_http_loop_ctx *ctx = conn->ctx;
+  lander_ctx *c_ctx = ctx->c;
+
+  if (!lander_insert_entry(ctx, secure)) {
+    return lnm_http_step_err_res;
+  }
+
+  lsm_entry_attr_insert_uint8_t(c_ctx->entry, lander_attr_type_entry_type,
+                                lander_entry_type_placeholder);
+
+  return lnm_http_step_err_done;
+}
+
+lnm_http_step_err lander_post_placeholder(lnm_http_conn *conn) {
+  return __lander_post_placeholder(conn, false);
+}
+
+lnm_http_step_err lander_post_placeholder_secure(lnm_http_conn *conn) {
+  return __lander_post_placeholder(conn, true);
+}

src/lander/lander_steps.c

@@ -5,6 +5,7 @@
 #include "lnm/loop.h"
 
 #include "lander.h"
+#include "lsm/store.h"
 
 lnm_http_step_err lander_stream_body_to_entry(lnm_http_conn *conn) {
   lnm_http_loop_ctx *ctx = conn->ctx;
@@ -35,3 +36,48 @@ lnm_http_step_err lander_commit_entry(lnm_http_conn *conn) {
 
   return lnm_http_step_err_done;
 }
+
+lnm_http_step_err lander_auth_or_placeholder(lnm_http_conn *conn) {
+  lnm_http_loop_ctx *ctx = conn->ctx;
+  lnm_http_loop_gctx *gctx = ctx->g;
+  lander_gctx *c_gctx = gctx->c;
+  lander_ctx *c_ctx = ctx->c;
+
+  const char *key_s;
+  size_t key_len = lnm_http_req_route_segment(&key_s, &ctx->req, "key");
+
+  // Only predefined keys can be placeholders
+  if (key_len == 0) {
+    return lnm_http_loop_step_auth(conn);
+  }
+
+  lsm_str *key;
+  lsm_str_init_copy_n(&key, key_s, key_len);
+
+  lsm_error res = lsm_store_open_write(&c_ctx->entry, c_gctx->store, key);
+
+  lsm_str_free(key);
+
+  switch (res) {
+  case lsm_error_ok: {
+    lander_entry_type t;
+
+    // If the entry is a placeholder, the request is always authenticated
+    if ((lsm_entry_attr_get_uint8_t(
+             &t, c_ctx->entry, lander_attr_type_entry_type) == lsm_error_ok) &&
+        (t == lander_entry_type_placeholder)) {
+      return lnm_http_step_err_done;
+    } else {
+      return lnm_http_loop_step_auth(conn);
+    }
+  } break;
+  case lsm_error_not_found:
+    return lnm_http_loop_step_auth(conn);
+    break;
+  default:
+    ctx->res.status = lnm_http_status_internal_server_error;
+    return lnm_http_step_err_res;
+  }
+
+  return lnm_http_step_err_done;
+}

src/main.c

@@ -34,62 +34,77 @@ lnm_http_loop *loop_init(lander_gctx *gctx, const char *api_key) {
   lnm_http_route_step_append(route, lander_commit_entry, true);
 
   lnm_http_router_add(&route, router, lnm_http_method_post, "/s/");
-  lnm_http_route_step_append(route, lnm_http_loop_step_auth, false);
+  lnm_http_route_step_append(route, lander_auth_or_placeholder, false);
   lnm_http_route_step_append(route, lander_post_redirect, false);
   lnm_http_route_step_append(route, lnm_http_loop_step_body_to_buf, false);
   lnm_http_route_step_append(route, lander_post_redirect_body_to_attr, false);
   lnm_http_route_step_append(route, lander_commit_entry, true);
 
   lnm_http_router_add(&route, router, lnm_http_method_post, "/sl/");
-  lnm_http_route_step_append(route, lnm_http_loop_step_auth, false);
+  lnm_http_route_step_append(route, lander_auth_or_placeholder, false);
   lnm_http_route_step_append(route, lander_post_redirect_secure, false);
   lnm_http_route_step_append(route, lnm_http_loop_step_body_to_buf, false);
   lnm_http_route_step_append(route, lander_post_redirect_body_to_attr, false);
   lnm_http_route_step_append(route, lander_commit_entry, true);
 
   lnm_http_router_add(&route, router, lnm_http_method_post, "/s/:key");
-  lnm_http_route_step_append(route, lnm_http_loop_step_auth, false);
+  lnm_http_route_step_append(route, lander_auth_or_placeholder, false);
   lnm_http_route_step_append(route, lander_post_redirect, false);
   lnm_http_route_step_append(route, lnm_http_loop_step_body_to_buf, false);
   lnm_http_route_step_append(route, lander_post_redirect_body_to_attr, false);
   lnm_http_route_step_append(route, lander_commit_entry, true);
 
   lnm_http_router_add(&route, router, lnm_http_method_post, "/p/");
-  lnm_http_route_step_append(route, lnm_http_loop_step_auth, false);
+  lnm_http_route_step_append(route, lander_auth_or_placeholder, false);
   lnm_http_route_step_append(route, lander_post_paste, false);
   lnm_http_route_step_append(route, lander_stream_body_to_entry, false);
   lnm_http_route_step_append(route, lander_commit_entry, true);
 
   lnm_http_router_add(&route, router, lnm_http_method_post, "/pl/");
-  lnm_http_route_step_append(route, lnm_http_loop_step_auth, false);
+  lnm_http_route_step_append(route, lander_auth_or_placeholder, false);
   lnm_http_route_step_append(route, lander_post_paste_secure, false);
   lnm_http_route_step_append(route, lander_stream_body_to_entry, false);
   lnm_http_route_step_append(route, lander_commit_entry, true);
 
   lnm_http_router_add(&route, router, lnm_http_method_post, "/p/:key");
-  lnm_http_route_step_append(route, lnm_http_loop_step_auth, false);
+  lnm_http_route_step_append(route, lander_auth_or_placeholder, false);
   lnm_http_route_step_append(route, lander_post_paste, false);
   lnm_http_route_step_append(route, lander_stream_body_to_entry, false);
   lnm_http_route_step_append(route, lander_commit_entry, true);
 
   lnm_http_router_add(&route, router, lnm_http_method_post, "/f/");
-  lnm_http_route_step_append(route, lnm_http_loop_step_auth, false);
+  lnm_http_route_step_append(route, lander_auth_or_placeholder, false);
   lnm_http_route_step_append(route, lander_post_file, false);
   lnm_http_route_step_append(route, lander_stream_body_to_entry, false);
   lnm_http_route_step_append(route, lander_commit_entry, true);
 
   lnm_http_router_add(&route, router, lnm_http_method_post, "/fl/");
-  lnm_http_route_step_append(route, lnm_http_loop_step_auth, false);
+  lnm_http_route_step_append(route, lander_auth_or_placeholder, false);
   lnm_http_route_step_append(route, lander_post_file_secure, false);
   lnm_http_route_step_append(route, lander_stream_body_to_entry, false);
   lnm_http_route_step_append(route, lander_commit_entry, true);
 
   lnm_http_router_add(&route, router, lnm_http_method_post, "/f/:key");
-  lnm_http_route_step_append(route, lnm_http_loop_step_auth, false);
+  lnm_http_route_step_append(route, lander_auth_or_placeholder, false);
   lnm_http_route_step_append(route, lander_post_file, false);
   lnm_http_route_step_append(route, lander_stream_body_to_entry, false);
   lnm_http_route_step_append(route, lander_commit_entry, true);
 
+  lnm_http_router_add(&route, router, lnm_http_method_post, "/h/");
+  lnm_http_route_step_append(route, lnm_http_loop_step_auth, false);
+  lnm_http_route_step_append(route, lander_post_placeholder, false);
+  lnm_http_route_step_append(route, lander_commit_entry, true);
+
+  lnm_http_router_add(&route, router, lnm_http_method_post, "/h/:key");
+  lnm_http_route_step_append(route, lnm_http_loop_step_auth, false);
+  lnm_http_route_step_append(route, lander_post_placeholder, false);
+  lnm_http_route_step_append(route, lander_commit_entry, true);
+
+  lnm_http_router_add(&route, router, lnm_http_method_post, "/hs/");
+  lnm_http_route_step_append(route, lnm_http_loop_step_auth, false);
+  lnm_http_route_step_append(route, lander_post_placeholder_secure, false);
+  lnm_http_route_step_append(route, lander_commit_entry, true);
+
   lnm_http_loop_router_set(hl, router);
 
   return hl;
@@ -140,5 +155,5 @@ int main() {
   lnm_linfo("main", "Store loaded containing %lu entries",
             lsm_store_size(c_gctx->store));
   lnm_http_loop *hl = loop_init(c_gctx, api_key);
-  lnm_http_loop_run(hl, port, 1, 0);
+  lnm_http_loop_run(hl, port, 1, 1);
 }