From: Alan T. DeKok <aland@freeradius.org>
Date: Sun, 23 Jan 2022 14:02:16 +0000 (-0500)
Subject: notes for DHCPv4 encodings
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7fb4a75b7782f7dc37120759cb89d3dd76f1813f;p=thirdparty%2Ffreeradius-server.git

notes for DHCPv4 encodings
---

diff --git a/src/protocols/dhcpv4/decode.c b/src/protocols/dhcpv4/decode.c
index e7973dca78..9b12ba6b33 100644
--- a/src/protocols/dhcpv4/decode.c
+++ b/src/protocols/dhcpv4/decode.c
@@ -548,6 +548,21 @@ ssize_t fr_dhcpv4_decode_option(TALLOC_CTX *ctx, fr_pair_list_t *out,
 
 	if (da->type == FR_TYPE_VSA) return decode_vsa(ctx, out, da, data + 2, data[1]);
 
+	/*
+	 *	@todo - RFC 2131 Section 4.1 says:
+	 *
+	 *	  The client concatenates the values of multiple
+	 *	  instances of the same option into a single parameter
+	 *	  list for configuration.
+	 *
+	 *	which presumably also means the same for the server on reception.
+	 *
+	 *	TBH, it would be simplest to have a thread-local array
+	 *	for temporary work.  If there are multiple options of
+	 *	the same number, then the values for those options get
+	 *	mashed into the temporary buffer.  Then, that buffer
+	 *	gets used for value decoding.
+	 */
 	ret = decode_value(ctx, out, da, data + 2, data[1]);
 	if (ret < 0) {
 		fr_dict_unknown_free(&da);
diff --git a/src/protocols/dhcpv4/encode.c b/src/protocols/dhcpv4/encode.c
index bc1076a9dd..1841f5c407 100644
--- a/src/protocols/dhcpv4/encode.c
+++ b/src/protocols/dhcpv4/encode.c
@@ -242,6 +242,24 @@ static ssize_t encode_rfc_hdr(fr_dbuff_t *dbuff,
 			break;
 		}
 
+		/*
+		 *	@todo - RFC 2131 Section 4.1 says:
+		 *
+		 *	  The client concatenates the values of multiple
+		 *	  instances of the same option into a single parameter
+		 *	  list for configuration.
+		 *
+		 *	so if we have multiple options of the same
+		 *	number, then pack them as much as possible.
+		 *
+		 *	TBH, it would be simplest to have a
+		 *	thread-local array for temporary work.  If
+		 *	there are multiple options of the same number,
+		 *	then the values for those options get mashed
+		 *	into the temporary buffer.  Then, that buffer
+		 *	gets copied to the actual packet, with headers
+		 *	being added as necessary.
+		 */
 		len = encode_value(&work_dbuff, da_stack, depth, cursor, encode_ctx);
 		if (len < -1) return len;
 		if (len == -1) {