File libslirp-fix-dhcp-2.patch of Package libslirp.24201

From d7fb54218424c3b2517aee5b391ced0f75386a5d Mon Sep 17 00:00:00 2001
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Mon, 21 Jun 2021 08:38:32 +0200
Subject: [PATCH] dhcp: Always send DHCP_OPT_LEN bytes in options

RFC2131 suggests that the options field may be at least 312 bytes.
Some DHCP clients seem to assume that it has to be at least 312 bytes.

Fixes #51
Fixes: f13cad45b25d92760bb0ad67bec0300a4d7d5275 ("bootp: limit
vendor-specific area to input packet memory buffer")

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
---
 src/bootp.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/bootp.c b/src/bootp.c
index 0a35873..d78d61b 100644
--- a/src/bootp.c
+++ b/src/bootp.c
@@ -355,13 +355,13 @@ static void bootp_reply(Slirp *slirp,
         q += sizeof(nak_msg) - 1;
     }
     assert(q < end);
-    *q = RFC1533_END;
+    *q++ = RFC1533_END;
 
     daddr.sin_addr.s_addr = 0xffffffffu;
 
-    assert ((q - rbp->bp_vend + 1) <= DHCP_OPT_LEN);
+    assert(q <= end);
 
-    m->m_len = sizeof(struct bootp_t) + (q - rbp->bp_vend + 1) - sizeof(struct ip) - sizeof(struct udphdr);
+    m->m_len = sizeof(struct bootp_t) + (end - rbp->bp_vend) - sizeof(struct ip) - sizeof(struct udphdr);
     udp_output(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
 }
 
-- 
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