feat(lander): re-add authentication using LNM

lnm/include/lnm/http/loop.h

@@ -83,6 +83,8 @@ lnm_err lnm_http_loop_route_add(lnm_http_loop *hl, lnm_http_route *route);
 
 lnm_err lnm_http_loop_run(lnm_http_loop *hl, uint16_t port);
 
+void lnm_http_loop_set_api_key(lnm_http_loop *hl, const char *api_key);
+
 /**
  * Represents what state an HTTP loop request is currently in.
  */
@@ -115,6 +117,7 @@ typedef struct lnm_http_loop_gctx {
   lnm_http_ctx_init_fn ctx_init;
   lnm_http_ctx_reset_fn ctx_reset;
   lnm_http_ctx_free_fn ctx_free;
+  const char *api_key;
   void *c;
 } lnm_http_loop_gctx;
 
@@ -130,4 +133,6 @@ typedef struct lnm_http_loop_ctx {
 
 lnm_http_step_err lnm_http_loop_step_body_to_buf(lnm_http_conn *conn);
 
+lnm_http_step_err lnm_http_loop_step_auth(lnm_http_conn *conn);
+
 #endif

lnm/src/http/lnm_http_loop.c

@@ -126,3 +126,8 @@ lnm_err lnm_http_loop_run(lnm_http_loop *hl, uint16_t port) {
   LNM_RES(lnm_loop_setup(hl, port));
   return lnm_loop_run(hl);
 }
+
+void lnm_http_loop_set_api_key(lnm_http_loop *hl, const char *api_key) {
+  lnm_http_loop_gctx *gctx = hl->gctx;
+  gctx->api_key = api_key;
+}

lnm/src/http/lnm_http_loop_steps.c

@@ -1,5 +1,6 @@
 #include <string.h>
 
+#include "lnm/http/consts.h"
 #include "lnm/http/loop.h"
 #include "lnm/loop.h"
 
@@ -22,3 +23,22 @@ lnm_http_step_err lnm_http_loop_step_body_to_buf(lnm_http_conn *conn) {
              ? lnm_http_step_err_done
              : lnm_http_step_err_io_needed;
 }
+
+lnm_http_step_err lnm_http_loop_step_auth(lnm_http_conn *conn) {
+  lnm_http_loop_ctx *ctx = conn->ctx;
+
+  // If there's no API key, requests are always authorized
+  bool authorized = ctx->g->api_key == NULL;
+
+  const char *value;
+  size_t value_len;
+
+  if (!authorized && lnm_http_req_header_get_s(&value, &value_len, &ctx->req,
+                                               "X-Api-Key") == lnm_err_ok) {
+    authorized = (value_len == strlen(ctx->g->api_key)) &&
+                 (memcmp(value, ctx->g->api_key, value_len) == 0);
+  }
+
+  ctx->res.status = authorized ? ctx->res.status : lnm_http_status_unauthorized;
+  return authorized ? lnm_http_step_err_done : lnm_http_step_err_res;
+}