src/net/tcpip.c

   1 #include <stdint.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include <errno.h>
   5 #include <byteswap.h>
   6 #include <ipxe/iobuf.h>
   7 #include <ipxe/tables.h>
   8 #include <ipxe/ipstat.h>
   9 #include <ipxe/netdevice.h>
  10 #include <ipxe/tcpip.h>
  11
  12 /** @file
  13  *
  14  * Transport-network layer interface
  15  *
  16  * This file contains functions and utilities for the
  17  * TCP/IP transport-network layer interface
  18  */
  19
  20 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  21
  22 /**
  23  * Process a received TCP/IP packet
  24  *
  25  * @v iobuf             I/O buffer
  26  * @v netdev            Network device
  27  * @v tcpip_proto       Transport-layer protocol number
  28  * @v st_src            Partially-filled source address
  29  * @v st_dest           Partially-filled destination address
  30  * @v pshdr_csum        Pseudo-header checksum
  31  * @v stats             IP statistics
  32  * @ret rc              Return status code
  33  *
  34  * This function expects a transport-layer segment from the network
  35  * layer.  The network layer should fill in as much as it can of the
  36  * source and destination addresses (i.e. it should fill in the
  37  * address family and the network-layer addresses, but leave the ports
  38  * and the rest of the structures as zero).
  39  */
  40 int tcpip_rx ( struct io_buffer *iobuf, struct net_device *netdev,
  41                uint8_t tcpip_proto, struct sockaddr_tcpip *st_src,
  42                struct sockaddr_tcpip *st_dest, uint16_t pshdr_csum,
  43                struct ip_statistics *stats ) {
  44         struct tcpip_protocol *tcpip;
  45
  46         /* Hand off packet to the appropriate transport-layer protocol */
  47         for_each_table_entry ( tcpip, TCPIP_PROTOCOLS ) {
  48                 if ( tcpip->tcpip_proto == tcpip_proto ) {
  49                         DBG ( "TCP/IP received %s packet\n", tcpip->name );
  50                         stats->in_delivers++;
  51                         return tcpip->rx ( iobuf, netdev, st_src, st_dest,
  52                                            pshdr_csum );
  53                 }
  54         }
  55
  56         DBG ( "Unrecognised TCP/IP protocol %d\n", tcpip_proto );
  57         stats->in_unknown_protos++;
  58         free_iob ( iobuf );
  59         return -EPROTONOSUPPORT;
  60 }
  61
  62 /**
  63  * Find TCP/IP network-layer protocol
  64  *
  65  * @v st_dest           Destination address
  66  * @ret tcpip_net       TCP/IP network-layer protocol, or NULL if not found
  67  */
  68 static struct tcpip_net_protocol *
  69 tcpip_net_protocol ( struct sockaddr_tcpip *st_dest ) {
  70         struct tcpip_net_protocol *tcpip_net;
  71
  72         for_each_table_entry ( tcpip_net, TCPIP_NET_PROTOCOLS ) {
  73                 if ( tcpip_net->sa_family == st_dest->st_family )
  74                         return tcpip_net;
  75         }
  76
  77         DBG ( "Unrecognised TCP/IP address family %d\n", st_dest->st_family );
  78         return NULL;
  79 }
  80
  81 /**
  82  * Transmit a TCP/IP packet
  83  *
  84  * @v iobuf             I/O buffer
  85  * @v tcpip_protocol    Transport-layer protocol
  86  * @v st_src            Source address, or NULL to use route default
  87  * @v st_dest           Destination address
  88  * @v netdev            Network device to use if no route found, or NULL
  89  * @v trans_csum        Transport-layer checksum to complete, or NULL
  90  * @ret rc              Return status code
  91  */
  92 int tcpip_tx ( struct io_buffer *iobuf, struct tcpip_protocol *tcpip_protocol,
  93                struct sockaddr_tcpip *st_src, struct sockaddr_tcpip *st_dest,
  94                struct net_device *netdev, uint16_t *trans_csum ) {
  95         struct tcpip_net_protocol *tcpip_net;
  96
  97         /* Hand off packet to the appropriate network-layer protocol */
  98         tcpip_net = tcpip_net_protocol ( st_dest );
  99         if ( tcpip_net ) {
 100                 DBG ( "TCP/IP sending %s packet\n", tcpip_net->name );
 101                 return tcpip_net->tx ( iobuf, tcpip_protocol, st_src, st_dest,
 102                                        netdev, trans_csum );
 103         }
 104
 105         free_iob ( iobuf );
 106         return -EAFNOSUPPORT;
 107 }
 108
 109 /**
 110  * Determine transmitting network device
 111  *
 112  * @v st_dest           Destination address
 113  * @ret netdev          Network device, or NULL
 114  */
 115 struct net_device * tcpip_netdev ( struct sockaddr_tcpip *st_dest ) {
 116         struct tcpip_net_protocol *tcpip_net;
 117
 118         /* Hand off to the appropriate network-layer protocol */
 119         tcpip_net = tcpip_net_protocol ( st_dest );
 120         if ( tcpip_net )
 121                 return tcpip_net->netdev ( st_dest );
 122
 123         return NULL;
 124 }
 125
 126 /**
 127  * Determine maximum transmission unit
 128  *
 129  * @v st_dest           Destination address
 130  * @ret mtu             Maximum transmission unit
 131  */
 132 size_t tcpip_mtu ( struct sockaddr_tcpip *st_dest ) {
 133         struct tcpip_net_protocol *tcpip_net;
 134         struct net_device *netdev;
 135         size_t mtu;
 136
 137         /* Find appropriate network-layer protocol */
 138         tcpip_net = tcpip_net_protocol ( st_dest );
 139         if ( ! tcpip_net )
 140                 return 0;
 141
 142         /* Find transmitting network device */
 143         netdev = tcpip_net->netdev ( st_dest );
 144         if ( ! netdev )
 145                 return 0;
 146
 147         /* Calculate MTU */
 148         mtu = ( netdev->max_pkt_len - netdev->ll_protocol->ll_header_len -
 149                 tcpip_net->header_len );
 150
 151         return mtu;
 152 }
 153
 154 /**
 155  * Calculate continued TCP/IP checkum
 156  *
 157  * @v partial           Checksum of already-summed data, in network byte order
 158  * @v data              Data buffer
 159  * @v len               Length of data buffer
 160  * @ret cksum           Updated checksum, in network byte order
 161  *
 162  * Calculates a TCP/IP-style 16-bit checksum over the data block.  The
 163  * checksum is returned in network byte order.
 164  *
 165  * This function may be used to add new data to an existing checksum.
 166  * The function assumes that both the old data and the new data start
 167  * on even byte offsets; if this is not the case then you will need to
 168  * byte-swap either the input partial checksum, the output checksum,
 169  * or both.  Deciding which to swap is left as an exercise for the
 170  * interested reader.
 171  */
 172 uint16_t generic_tcpip_continue_chksum ( uint16_t partial,
 173                                          const void *data, size_t len ) {
 174         unsigned int cksum = ( ( ~partial ) & 0xffff );
 175         unsigned int value;
 176         unsigned int i;
 177
 178         for ( i = 0 ; i < len ; i++ ) {
 179                 value = * ( ( uint8_t * ) data + i );
 180                 if ( i & 1 ) {
 181                         /* Odd bytes: swap on little-endian systems */
 182                         value = be16_to_cpu ( value );
 183                 } else {
 184                         /* Even bytes: swap on big-endian systems */
 185                         value = le16_to_cpu ( value );
 186                 }
 187                 cksum += value;
 188                 if ( cksum > 0xffff )
 189                         cksum -= 0xffff;
 190         }
 191
 192         return ( ~cksum );
 193 }
 194
 195 /**
 196  * Calculate TCP/IP checkum
 197  *
 198  * @v data              Data buffer
 199  * @v len               Length of data buffer
 200  * @ret cksum           Checksum, in network byte order
 201  *
 202  * Calculates a TCP/IP-style 16-bit checksum over the data block.  The
 203  * checksum is returned in network byte order.
 204  */
 205 uint16_t tcpip_chksum ( const void *data, size_t len ) {
 206         return tcpip_continue_chksum ( TCPIP_EMPTY_CSUM, data, len );
 207 }
 208
 209 /**
 210  * Bind to local TCP/IP port
 211  *
 212  * @v st_local          Local TCP/IP socket address, or NULL
 213  * @v available         Function to check port availability
 214  * @ret port            Local port number, or negative error
 215  */
 216 int tcpip_bind ( struct sockaddr_tcpip *st_local,
 217                  int ( * available ) ( int port ) ) {
 218         uint16_t flags = 0;
 219         uint16_t try_port = 0;
 220         uint16_t min_port;
 221         uint16_t max_port;
 222         unsigned int offset;
 223         unsigned int i;
 224
 225         /* Extract parameters from local socket address */
 226         if ( st_local ) {
 227                 flags = st_local->st_flags;
 228                 try_port = ntohs ( st_local->st_port );
 229         }
 230
 231         /* If an explicit port is specified, check its availability */
 232         if ( try_port )
 233                 return available ( try_port );
 234
 235         /* Otherwise, find an available port in the range [1,1023] or
 236          * [1025,65535] as appropriate.
 237          */
 238         min_port = ( ( ( ~flags ) & TCPIP_BIND_PRIVILEGED ) + 1 );
 239         max_port = ( ( flags & TCPIP_BIND_PRIVILEGED ) - 1 );
 240         offset = random();
 241         for ( i = 0 ; i <= max_port ; i++ ) {
 242                 try_port = ( ( i + offset ) & max_port );
 243                 if ( try_port < min_port )
 244                         continue;
 245                 if ( available ( try_port ) < 0 )
 246                         continue;
 247                 return try_port;
 248         }
 249         return -EADDRINUSE;
 250 }