From 39524963781d589a2a7da3bed70280b51811f8d8 Mon Sep 17 00:00:00 2001
From: Jef Roosens <roosensjef@gmail.com>
Date: Wed, 28 Aug 2024 22:39:51 +0200
Subject: [PATCH] feat(lander): implement placeholder keys

---
 CHANGELOG.md                    |  5 ++++
 include/lander.h                | 11 ++++++++
 lsm/include/lsm/store.h         |  3 ++-
 lsm/src/store/lsm_store_entry.c |  6 +++--
 src/lander/lander_post.c        | 31 +++++++++++++++++++++-
 src/lander/lander_steps.c       | 46 +++++++++++++++++++++++++++++++++
 src/main.c                      | 35 ++++++++++++++++++-------
 7 files changed, 123 insertions(+), 14 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a31cd42..f179b59 100644
--- a/CHANGELOG.md
+++ b/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
diff --git a/include/lander.h b/include/lander.h
index 9ebbdf2..09c53fc 100644
--- a/include/lander.h
+++ b/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.
  */
diff --git a/lsm/include/lsm/store.h b/lsm/include/lsm/store.h
index e2d7d86..6018a5e 100644
--- a/lsm/include/lsm/store.h
+++ b/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
diff --git a/lsm/src/store/lsm_store_entry.c b/lsm/src/store/lsm_store_entry.c
index 93a570b..2d73beb 100644
--- a/lsm/src/store/lsm_store_entry.c
+++ b/lsm/src/store/lsm_store_entry.c
@@ -211,8 +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;
diff --git a/src/lander/lander_post.c b/src/lander/lander_post.c
index 7befe03..f074f5a 100644
--- a/src/lander/lander_post.c
+++ b/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);
+}
diff --git a/src/lander/lander_steps.c b/src/lander/lander_steps.c
index 8e2d702..502f733 100644
--- a/src/lander/lander_steps.c
+++ b/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;
+}
diff --git a/src/main.c b/src/main.c
index 12601b3..a6727a6 100644
--- a/src/main.c
+++ b/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);
 }