From 1502e8dab92a6aa8c778d782b85aaca2e200d11a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?F=C3=A9lix=20Baylac-Jacqu=C3=A9?= <felix@alternativebit.fr>
Date: Tue, 4 Oct 2022 11:34:43 +0200
Subject: [PATCH] Some notes

---
 nscd/connections.c   | 1 +
 nscd/hstcache.c      | 9 +++++++++
 nscd/nscd-client.h   | 1 +
 nscd/nscd_gethst_r.c | 2 ++
 resolv/netdb.h       | 1 +
 5 files changed, 14 insertions(+)

diff --git a/nscd/connections.c b/nscd/connections.c
index 531d2e83df..7d62126430 100644
--- a/nscd/connections.c
+++ b/nscd/connections.c
@@ -1163,6 +1163,7 @@ request from '%s' [%ld] not handled due to missing permission"),
 	dbg_log ("\t%s", serv2str[req->type]);
     }
 
+  // HERE: request handler
   /* Handle the request.  */
   switch (req->type)
     {
diff --git a/nscd/hstcache.c b/nscd/hstcache.c
index 69472f1bc0..7ddcc217da 100644
--- a/nscd/hstcache.c
+++ b/nscd/hstcache.c
@@ -60,6 +60,7 @@ const struct iovec hst_iov_disabled =
 };
 
 
+// HERE: interesting test cases
 /* This is the standard reply in case we haven't found the dataset.  */
 static const hst_response_header notfound =
 {
@@ -269,19 +270,26 @@ cache_addhst (struct database_dyn *db, int fd, request_header *req,
 
       cp = dataset->strdata;
 
+      // Payload????? Not sure :/
+      // 1. hname string
       cp = mempcpy (cp, hst->h_name, h_name_len);
+      // 2. table containing the lenghts of each alias
       cp = mempcpy (cp, h_aliases_len, h_aliases_cnt * sizeof (uint32_t));
 
       /* The normal addresses first.  */
       addresses = cp;
+      // 3. Iterating on the result addr, serializing them. Each part is h_length wide.
+      // TODO: find h_length size.
       for (cnt = 0; cnt < h_addr_list_cnt; ++cnt)
 	cp = mempcpy (cp, hst->h_addr_list[cnt], hst->h_length);
 
+      // 4. Iterating on the aliases, serializing them one by one according to their size previously sent.
       /* Then the aliases.  */
       aliases = cp;
       for (cnt = 0; cnt < h_aliases_cnt; ++cnt)
 	cp = mempcpy (cp, hst->h_aliases[cnt], h_aliases_len[cnt]);
 
+      // 5. Size sanity check
       assert (cp
 	      == dataset->strdata + total - offsetof (struct dataset,
 						      strdata));
@@ -424,6 +432,7 @@ lookup (int type, void *key, struct hostent *resultbufp, char *buffer,
 }
 
 
+// HERE: top-level hst imp
 static time_t
 addhstbyX (struct database_dyn *db, int fd, request_header *req,
 	   void *key, uid_t uid, struct hashentry *he, struct datahead *dh)
diff --git a/nscd/nscd-client.h b/nscd/nscd-client.h
index ca9e6def1a..66c0d6524c 100644
--- a/nscd/nscd-client.h
+++ b/nscd/nscd-client.h
@@ -114,6 +114,7 @@ typedef struct
 } gr_response_header;
 
 
+// HERE: header struct
 /* Structure sent in reply to host query.  Note that this struct is
    sent also if the service is disabled or there is no record found.  */
 typedef struct
diff --git a/nscd/nscd_gethst_r.c b/nscd/nscd_gethst_r.c
index 31d13580a1..1310824890 100644
--- a/nscd/nscd_gethst_r.c
+++ b/nscd/nscd_gethst_r.c
@@ -129,6 +129,7 @@ __nscd_get_nl_timestamp (void)
 
 int __nss_have_localdomain attribute_hidden;
 
+//HERE impl. Client!?!? It reads from the socket to **result
 static int
 nscd_gethst_r (const char *key, size_t keylen, request_type type,
 	       struct hostent *resultbuf, char *buffer, size_t buflen,
@@ -214,6 +215,7 @@ nscd_gethst_r (const char *key, size_t keylen, request_type type,
 
   if (h_name == NULL)
     {
+      // Read here
       sock = __nscd_open_socket (key, keylen, type, &hst_resp,
 				 sizeof (hst_resp));
       if (sock == -1)
diff --git a/resolv/netdb.h b/resolv/netdb.h
index ac268f035f..76fbd97f79 100644
--- a/resolv/netdb.h
+++ b/resolv/netdb.h
@@ -94,6 +94,7 @@ extern const char *hstrerror (int __err_num) __THROW;
 #endif
 
 
+// HERE: payload??? Nope, it's transformed
 /* Description of data base entry for a single host.  */
 struct hostent
 {