From b6aca482774541522f32163438904b176c25e690 Mon Sep 17 00:00:00 2001
From: Maria Matejka <mq@ucw.cz>
Date: Tue, 10 Sep 2024 20:43:55 +0200
Subject: [PATCH] Flock: telnet request sends the request

---
 flock/ctl.c        |  3 ++
 flock/flock.h      |  2 +
 flock/hypervisor.c | 94 ++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 96 insertions(+), 3 deletions(-)

diff --git a/flock/ctl.c b/flock/ctl.c
index 1552993b..e2dc8f51 100644
--- a/flock/ctl.c
+++ b/flock/ctl.c
@@ -184,9 +184,12 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	  case 3: /* telnet listener open */
 	    if ((ctx->type != 7) || (ctx->value != 22))
 	      CBOR_PARSER_ERROR("Expected null, got %u-%u", ctx->type, ctx->value);
+	    /* TODO: allow this also for machines */
 
 	    log(L_INFO "Requested telnet open");
 
+	    hexp_get_telnet(ctx->sock, NULL);
+
 	    ctx->major_state = 1;
 	    break;
 
diff --git a/flock/flock.h b/flock/flock.h
index 8cc33480..076d7141 100644
--- a/flock/flock.h
+++ b/flock/flock.h
@@ -25,6 +25,8 @@ void hcs_parser_cleanup(struct cbor_parser_context *ctx);
 const char *hcs_error(struct cbor_parser_context *ctx);
 bool hcs_complete(struct cbor_parser_context *ctx);
 
+void hexp_get_telnet(sock *, const char *name);
+
 extern event reboot_event, poweroff_event;
 extern event_list shutdown_event_list;
 
diff --git a/flock/hypervisor.c b/flock/hypervisor.c
index 217eb5a7..b826a046 100644
--- a/flock/hypervisor.c
+++ b/flock/hypervisor.c
@@ -1,7 +1,9 @@
 #include "lib/birdlib.h"
 
-#include "lib/resource.h"
+#include "lib/cbor.h"
+#include "lib/hash.h"
 #include "lib/io-loop.h"
+#include "lib/resource.h"
 #include "lib/socket.h"
 
 #include "flock/flock.h"
@@ -149,8 +151,18 @@ hypervisor_exposed_parent_err(sock *sk UNUSED, int e UNUSED)
 static int
 hypervisor_exposed_child_rx(sock *sk, uint size UNUSED)
 {
-  log(L_INFO "HV EC RX");
-  recvmsg(sk->fd, NULL, 0);
+  byte buf[128];
+  struct iovec v = {
+    .iov_base = buf,
+    .iov_len = sizeof buf,
+  };
+  struct msghdr m = {
+    .msg_iov = &v,
+    .msg_iovlen = 1,
+  };
+  int e = recvmsg(sk->fd, &m, 0);
+  log(L_INFO "HV EC RX %d", e);
+
   return 0;
 }
 
@@ -211,3 +223,79 @@ hypervisor_exposed_fork(void)
   /* Wait for Godot */
   birdloop_minimalist_main();
 }
+
+
+/**
+ * Hypervisor's mapping between external ports and names
+ */
+
+#define HEXP_TELNET_KEY(tp)	tp->name, tp->hash
+#define HEXP_TELNET_NEXT(tp)	tp->next
+#define HEXP_TELNET_EQ(a,h,b,i)	((h) == (i)) && (!(a) && !(b) || !strcmp(a,b))
+#define HEXP_TELNET_FN(a,h)	h
+
+struct hexp_telnet_port {
+  struct hexp_telnet_port *next;
+  const char *name;
+  uint hash;
+  uint port;
+};
+
+static struct hexp_telnet {
+  pool *pool;
+  HASH(struct hexp_telnet_port) port_hash;
+} hexp_telnet;
+
+static void
+hexp_init_telnet(void)
+{
+  pool *p = rp_new(hcs_pool, hcs_pool->domain, "Hypervisor exposed telnets");
+  hexp_telnet.pool = p;
+  HASH_INIT(hexp_telnet.port_hash, p, 6);
+}
+
+static void
+hexp_have_telnet(sock *s, struct hexp_telnet_port *p)
+{
+  struct linpool *lp = lp_new(s->pool);
+  struct cbor_writer *cw = cbor_init(s->tbuf, s->tbsize, lp);
+  cbor_open_block_with_length(cw, 1);
+  cbor_add_int(cw, -2);
+  cbor_add_int(cw, p->port);
+  sk_send(s, cw->pt);
+  rfree(lp);
+}
+
+void
+hexp_get_telnet(sock *s, const char *name)
+{
+  if (!hexp_telnet.pool)
+    hexp_init_telnet();
+
+  uint h = name ? mem_hash(name, strlen(name)) : 0;
+  struct hexp_telnet_port *p = HASH_FIND(hexp_telnet.port_hash, HEXP_TELNET, name, h);
+  if (p)
+    return hexp_have_telnet(s, p);
+
+  uint8_t buf[64];
+  linpool *lp = lp_new(s->pool);
+  struct cbor_writer *cw = cbor_init(buf, sizeof buf, lp);
+  cbor_open_block_with_length(cw, 1);
+  cbor_add_int(cw, 1);
+  cw->cbor[cw->pt++] = 0xf6;
+
+  struct iovec v = {
+    .iov_base = buf,
+    .iov_len = cw->pt,
+  };
+  struct msghdr m = {
+    .msg_iov = &v,
+    .msg_iovlen = 1,
+  };
+
+  int e = sendmsg(he.s->fd, &m, 0);
+  if (e != cw->pt)
+    bug("sendmsg error handling not implemented, got %d (%m)", e);
+
+  rfree(lp);
+}