Clarified types and sizes of DHCP/BOOTP chaddr, sname, and file.

chaddr is a hardware address, with size specified seperately, whereas
sname and file are null terminated strings.

3 files changed, 21 insertions, 32 deletions

diff --git a/libnet/include/libnet/libnet-functions.h b/libnet/include/libnet/libnet-functions.h
index eff534e..949aaa4 100644
--- a/libnet/include/libnet/libnet-functions.h
+++ b/libnet/include/libnet/libnet-functions.h
@@ -1476,9 +1476,9 @@ libnet_ptag_t ptag);
  * @param yip
  * @param sip
  * @param gip
- * @param chaddr
- * @param sname
- * @param file
+ * @param chaddr, client hardware address, length is hlen
+ * @param sname, server host name, a null terminated string
+ * @param file, boot file name, a null terminated string
  * @param payload optional payload or NULL
  * @param payload_s payload length or 0
  * @param l pointer to a libnet context
@@ -1489,7 +1489,7 @@ libnet_ptag_t
 libnet_build_dhcpv4(uint8_t opcode, uint8_t htype, uint8_t hlen,
 uint8_t hopcount, uint32_t xid, uint16_t secs, uint16_t flags,
 uint32_t cip, uint32_t yip,  uint32_t sip, uint32_t gip, const uint8_t *chaddr,
-uint8_t *sname, const uint8_t *file, const uint8_t* payload, uint32_t payload_s, 
+const char *sname, const char *file, const uint8_t* payload, uint32_t payload_s, 
 libnet_t *l, libnet_ptag_t ptag);
 
 /**
@@ -1504,9 +1504,9 @@ libnet_t *l, libnet_ptag_t ptag);
  * @param yip
  * @param sip
  * @param gip
- * @param chaddr
- * @param sname
- * @param file
+ * @param chaddr, client hardware address, length is hlen
+ * @param sname, server host name, a null terminated string
+ * @param file, boot file name, a null terminated string
  * @param payload optional payload or NULL
  * @param payload_s payload length or 0
  * @param l pointer to a libnet context
@@ -1517,7 +1517,7 @@ libnet_ptag_t
 libnet_build_bootpv4(uint8_t opcode, uint8_t htype, uint8_t hlen,
 uint8_t hopcount, uint32_t xid, uint16_t secs, uint16_t flags,
 uint32_t cip, uint32_t yip,  uint32_t sip, uint32_t gip, const uint8_t *chaddr,
-uint8_t *sname, const uint8_t *file, const uint8_t* payload, uint32_t payload_s, 
+const char *sname, const char *file, const uint8_t* payload, uint32_t payload_s, 
 libnet_t *l, libnet_ptag_t ptag);
 
 /**
diff --git a/libnet/include/libnet/libnet-headers.h b/libnet/include/libnet/libnet-headers.h
index 009c6cf..11065c7 100644
--- a/libnet/include/libnet/libnet-headers.h
+++ b/libnet/include/libnet/libnet-headers.h
@@ -364,9 +364,9 @@ struct libnet_dhcpv4_hdr
     uint32_t dhcp_yip;        /* your IP */
     uint32_t dhcp_sip;        /* server's IP */
     uint32_t dhcp_gip;        /* gateway IP */
-    uint8_t dhcp_chaddr[16]; /* client hardware address */
-    uint8_t dhcp_sname[64];  /* server host name */
-    uint8_t dhcp_file[128];  /* boot file name */
+    uint8_t dhcp_chaddr[16]; /* client hardware address, len is dhcp_hlen */
+    char dhcp_sname[64];     /* server host name, null terminated string */
+    char dhcp_file[128];     /* boot file name, null terminated string */
     uint32_t dhcp_magic;      /* BOOTP magic header */
 #define DHCP_MAGIC                  0x63825363
 #define LIBNET_BOOTP_MIN_LEN        0x12c
diff --git a/libnet/src/libnet_build_dhcp.c b/libnet/src/libnet_build_dhcp.c
index d147958..7d3f172 100644
--- a/libnet/src/libnet_build_dhcp.c
+++ b/libnet/src/libnet_build_dhcp.c
@@ -43,7 +43,7 @@ libnet_ptag_t
 libnet_build_dhcpv4(uint8_t opcode, uint8_t htype, uint8_t hlen, 
 uint8_t hopcount, uint32_t xid, uint16_t secs, uint16_t flags,
 uint32_t cip, uint32_t yip, uint32_t sip, uint32_t gip, const uint8_t *chaddr,
-uint8_t *sname, const uint8_t *file, const uint8_t *payload, uint32_t payload_s,
+const char *sname, const char *file, const uint8_t *payload, uint32_t payload_s,
 libnet_t *l, libnet_ptag_t ptag)
 {
     uint32_t n, h;
@@ -82,32 +82,21 @@ libnet_t *l, libnet_ptag_t ptag)
     dhcp_hdr.dhcp_gip       = htonl(gip);
 
     if (chaddr)
-    { 
-        strncpy((char *)dhcp_hdr.dhcp_chaddr, (const char *)chaddr, sizeof (dhcp_hdr.dhcp_chaddr) - 2);
-    }
-    else
     {
-        memset(dhcp_hdr.dhcp_chaddr, 0, sizeof (dhcp_hdr.dhcp_chaddr));
+        size_t n = sizeof (dhcp_hdr.dhcp_chaddr);
+        if (hlen < n)
+            n = hlen;
+        memcpy(dhcp_hdr.dhcp_chaddr, chaddr, n);
     }
- 
     if (sname)
     { 
-        strncpy((const char *)dhcp_hdr.dhcp_sname, (char *)sname, sizeof (dhcp_hdr.dhcp_sname) - 2);
-    }
-    else
-    {
-        memset(dhcp_hdr.dhcp_sname, 0, sizeof (dhcp_hdr.dhcp_sname));
+        strncpy(dhcp_hdr.dhcp_sname, sname, sizeof (dhcp_hdr.dhcp_sname) - 1);
     }
-
     if (file)
     {
-        strncpy(dhcp_hdr.dhcp_file, file, sizeof (dhcp_hdr.dhcp_file) - 2);
-    }
-    else
-    {
-        memset(dhcp_hdr.dhcp_file, 0, sizeof(dhcp_hdr.dhcp_file));
+        strncpy(dhcp_hdr.dhcp_file, file, sizeof (dhcp_hdr.dhcp_file) - 1);
     }
-    dhcp_hdr.dhcp_magic = htonl(DHCP_MAGIC);    /* should this be tunable? */
+    dhcp_hdr.dhcp_magic = htonl(DHCP_MAGIC);
 
     n = libnet_pblock_append(l, p, (uint8_t *)&dhcp_hdr, LIBNET_DHCPV4_H);
     if (n == -1)
@@ -142,7 +131,7 @@ libnet_ptag_t
 libnet_build_bootpv4(uint8_t opcode, uint8_t htype, uint8_t hlen,
 uint8_t hopcount, uint32_t xid, uint16_t secs, uint16_t flags,
 uint32_t cip, uint32_t yip, uint32_t sip, uint32_t gip, const uint8_t *chaddr,
-uint8_t *sname, const uint8_t *file, const uint8_t *payload, uint32_t payload_s,
+const char *sname, const char *file, const uint8_t *payload, uint32_t payload_s,
 libnet_t *l, libnet_ptag_t ptag)
 {
     return (libnet_build_dhcpv4(opcode, htype, hlen, hopcount, xid, secs,
@@ -150,4 +139,4 @@ libnet_t *l, libnet_ptag_t ptag)
         l, ptag));
 }
 
-/* EOF */
\ No newline at end of file
+/* EOF */