From 41b399d672e07c5bfda777a13f0d804b54d044a5 Mon Sep 17 00:00:00 2001 From: Nikhil Chandru Rao Date: Wed, 28 Jun 2006 09:10:35 +0000 Subject: [PATCH] Fixed endianness of 16- and 32- bit values --- src/net/ipv4.c | 70 ++++++++++++++++++++++++++++---------------------- 1 file changed, 40 insertions(+), 30 deletions(-) diff --git a/src/net/ipv4.c b/src/net/ipv4.c index af22b325..91b2d7ff 100644 --- a/src/net/ipv4.c +++ b/src/net/ipv4.c @@ -107,21 +107,19 @@ static void ipv4_dump ( struct iphdr *iphdr __unused ) { DBG ( "\tVersion = %d\n", ( iphdr->verhdrlen & IP_MASK_VER ) / 16 ); DBG ( "\tHeader length = %d\n", iphdr->verhdrlen & IP_MASK_HLEN ); DBG ( "\tService = %d\n", iphdr->service ); - DBG ( "\tTotal length = %d\n", iphdr->len ); - DBG ( "\tIdent = %d\n", iphdr->ident ); - DBG ( "\tFrags/Offset = %d\n", iphdr->frags ); + DBG ( "\tTotal length = %d\n", ntohs ( iphdr->len ) ); + DBG ( "\tIdent = %d\n", ntohs ( iphdr->ident ) ); + DBG ( "\tFrags/Offset = %d\n", ntohs ( iphdr->frags ) ); DBG ( "\tIP TTL = %d\n", iphdr->ttl ); DBG ( "\tProtocol = %d\n", iphdr->protocol ); - DBG ( "\tHeader Checksum (at %p) = %x\n", &iphdr->chksum, - iphdr->chksum ); + DBG ( "\tHeader Checksum (at %p) = %x\n", &iphdr->chksum, + ntohs ( iphdr->chksum ) ); DBG ( "\tSource = %s\n", inet_ntoa ( iphdr->src ) ); DBG ( "\tDestination = %s\n", inet_ntoa ( iphdr->dest ) ); } /** * Complete the transport-layer checksum - * - * Refer to the note made in net/interface.c about this function */ void ipv4_tx_csum ( struct pk_buff *pkb, uint8_t trans_proto ) { @@ -234,7 +232,7 @@ int ipv4_uip_tx ( struct pk_buff *pkb ) { * This function expects a transport-layer segment and prepends the IP header */ int ipv4_tx ( struct pk_buff *pkb, uint16_t trans_proto, struct in_addr *dest ) { - struct iphdr *iphdr = pkb_push ( pkb, IP_HLEN ); + struct iphdr *iphdr = pkb_push ( pkb, sizeof ( *iphdr ) ); struct ipv4_miniroute *miniroute; struct net_device *netdev = NULL; struct in_addr next_hop; @@ -243,24 +241,23 @@ int ipv4_tx ( struct pk_buff *pkb, uint16_t trans_proto, struct in_addr *dest ) int rc; /* Fill up the IP header, except source address */ - iphdr->verhdrlen = ( IP_VER << 4 ) | ( IP_HLEN / 4 ); /* Version = 4, Header length = 5 */ - iphdr->service = IP_TOS; /* Service = 0, is not implemented */ - iphdr->len = htons ( pkb_len ( pkb ) ); /* Total packet length, in network byte order */ - iphdr->ident = next_ident++; /* Identification number */ - iphdr->frags = 0; /* Fragmentation is not implemented at the host */ - iphdr->ttl = IP_TTL; /* Time to live */ - iphdr->protocol = trans_proto; /* Transport-layer protocol - IP_XXX */ + iphdr->verhdrlen = ( IP_VER << 4 ) | ( sizeof ( *iphdr ) / 4 ); + iphdr->service = IP_TOS; + iphdr->len = htons ( pkb_len ( pkb ) ); + iphdr->ident = htons ( next_ident++ ); + iphdr->frags = 0; + iphdr->ttl = IP_TTL; + iphdr->protocol = trans_proto; - /* Calculate header checksum, in network byte order */ - iphdr->chksum = 0; - iphdr->chksum = htons ( calc_chksum ( iphdr, IP_HLEN ) ); /* Copy destination address */ - memcpy ( &iphdr->dest, dest, sizeof ( struct in_addr ) ); + iphdr->dest = *dest; /** - * All fields in the IP header filled in except the source network address (which requires routing). As - * the pseudo header requires the source address as well and updating the transport-layer checksum is - * done after routing. + * All fields in the IP header filled in except the source network + * address (which requires routing) and the header checksum (which + * requires the source network address). As the pseudo header requires + * the source address as well and the transport-layer checksum is + * updated after routing. * * Continue processing as in ipv4_uip_tx() */ @@ -288,6 +285,10 @@ int ipv4_tx ( struct pk_buff *pkb, uint16_t trans_proto, struct in_addr *dest ) /* Calculate the transport layer checksum */ ipv4_tx_csum ( pkb, trans_proto ); + /* Calculate header checksum, in network byte order */ + iphdr->chksum = 0; + iphdr->chksum = htons ( calc_chksum ( iphdr, sizeof ( *iphdr ) ) ); + /* Print IP4 header for debugging */ ipv4_dump ( iphdr ); @@ -367,7 +368,8 @@ static int ipv4_uip_rx ( struct pk_buff *pkb, * @v netdev Network device * @v ll_source Link-layer destination source * - * This function expects an IP4 network datagram. It will process the headers and send it to the transport layer + * This function expects an IP4 network datagram. It processes the headers + * and sends it to the transport layer. */ void ipv4_rx ( struct pk_buff *pkb, struct net_device *netdev __unused, const void *ll_source __unused ) { @@ -376,26 +378,34 @@ void ipv4_rx ( struct pk_buff *pkb, struct net_device *netdev __unused, struct in_addr *dest = &iphdr->dest; uint16_t chksum; + /* Sanity check */ + if ( pkb_len ( pkb ) < sizeof ( *iphdr ) ) { + DBG ( "IP datagram too short (%d bytes)\n", + pkb_len ( pkb ) ); + return; + } + /* Print IP4 header for debugging */ ipv4_dump ( iphdr ); - /* Process headers */ + /* Validate version and header length */ if ( iphdr->verhdrlen != 0x45 ) { DBG ( "Bad version and header length %x\n", iphdr->verhdrlen ); return; } - if ( iphdr->len != pkb_len ( pkb ) ) { - DBG ( "Bad total length %d\n", iphdr->len ); + /* Validate length of IP packet */ + if ( ntohs ( iphdr->len ) != pkb_len ( pkb ) ) { + DBG ( "Inconsistent packet length %d\n", + ntohs ( iphdr->len ) ); return; } - if ( ( chksum = ipv4_rx_csum ( pkb, iphdr->protocol ) ) != 0xffff ) { + /* Verify the checksum */ + if ( ( chksum = ipv4_rx_csum ( pkb, iphdr->protocol ) ) != 0xffff ) { DBG ( "Bad checksum %x\n", chksum ); } - /* Todo: Compute and verify the header checksum */ - /* To reduce code size, the following functions are not implemented: * 1. Check the destination address * 2. Check the TTL field @@ -403,7 +413,7 @@ void ipv4_rx ( struct pk_buff *pkb, struct net_device *netdev __unused, */ /* Strip header */ - pkb_pull ( pkb, IP_HLEN ); + pkb_pull ( pkb, sizeof ( *iphdr ) ); /* Send it to the transport layer */ trans_rx ( pkb, iphdr->protocol, src, dest );