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 sa_family         Address family
  66  * @ret tcpip_net       TCP/IP network-layer protocol, or NULL if not found
  67  */
  68 struct tcpip_net_protocol * tcpip_net_protocol ( sa_family_t sa_family ) {
  69         struct tcpip_net_protocol *tcpip_net;
  70
  71         for_each_table_entry ( tcpip_net, TCPIP_NET_PROTOCOLS ) {
  72                 if ( tcpip_net->sa_family == sa_family )
  73                         return tcpip_net;
  74         }
  75
  76         DBG ( "Unrecognised TCP/IP address family %d\n", sa_family );
  77         return NULL;
  78 }
  79
  80 /**
  81  * Transmit a TCP/IP packet
  82  *
  83  * @v iobuf             I/O buffer
  84  * @v tcpip_protocol    Transport-layer protocol
  85  * @v st_src            Source address, or NULL to use route default
  86  * @v st_dest           Destination address
  87  * @v netdev            Network device to use if no route found, or NULL
  88  * @v trans_csum        Transport-layer checksum to complete, or NULL
  89  * @ret rc              Return status code
  90  */
  91 int tcpip_tx ( struct io_buffer *iobuf, struct tcpip_protocol *tcpip_protocol,
  92                struct sockaddr_tcpip *st_src, struct sockaddr_tcpip *st_dest,
  93                struct net_device *netdev, uint16_t *trans_csum ) {
  94         struct tcpip_net_protocol *tcpip_net;
  95
  96         /* Hand off packet to the appropriate network-layer protocol */
  97         tcpip_net = tcpip_net_protocol ( st_dest->st_family );
  98         if ( tcpip_net ) {
  99                 DBG ( "TCP/IP sending %s packet\n", tcpip_net->name );
 100                 return tcpip_net->tx ( iobuf, tcpip_protocol, st_src, st_dest,
 101                                        netdev, trans_csum );
 102         }
 103
 104         free_iob ( iobuf );
 105         return -EAFNOSUPPORT;
 106 }
 107
 108 /**
 109  * Determine transmitting network device
 110  *
 111  * @v st_dest           Destination address
 112  * @ret netdev          Network device, or NULL
 113  */
 114 struct net_device * tcpip_netdev ( struct sockaddr_tcpip *st_dest ) {
 115         struct tcpip_net_protocol *tcpip_net;
 116
 117         /* Hand off to the appropriate network-layer protocol */
 118         tcpip_net = tcpip_net_protocol ( st_dest->st_family );
 119         if ( tcpip_net )
 120                 return tcpip_net->netdev ( st_dest );
 121
 122         return NULL;
 123 }
 124
 125 /**
 126  * Determine maximum transmission unit
 127  *
 128  * @v st_dest           Destination address
 129  * @ret mtu             Maximum transmission unit
 130  */
 131 size_t tcpip_mtu ( struct sockaddr_tcpip *st_dest ) {
 132         struct tcpip_net_protocol *tcpip_net;
 133         struct net_device *netdev;
 134         size_t mtu;
 135
 136         /* Find appropriate network-layer protocol */
 137         tcpip_net = tcpip_net_protocol ( st_dest->st_family );
 138         if ( ! tcpip_net )
 139                 return 0;
 140
 141         /* Find transmitting network device */
 142         netdev = tcpip_net->netdev ( st_dest );
 143         if ( ! netdev )
 144                 return 0;
 145
 146         /* Calculate MTU */
 147         mtu = ( netdev->mtu - tcpip_net->header_len );
 148
 149         return mtu;
 150 }
 151
 152 /**
 153  * Calculate continued TCP/IP checkum
 154  *
 155  * @v partial           Checksum of already-summed data, in network byte order
 156  * @v data              Data buffer
 157  * @v len               Length of data buffer
 158  * @ret cksum           Updated checksum, in network byte order
 159  *
 160  * Calculates a TCP/IP-style 16-bit checksum over the data block.  The
 161  * checksum is returned in network byte order.
 162  *
 163  * This function may be used to add new data to an existing checksum.
 164  * The function assumes that both the old data and the new data start
 165  * on even byte offsets; if this is not the case then you will need to
 166  * byte-swap either the input partial checksum, the output checksum,
 167  * or both.  Deciding which to swap is left as an exercise for the
 168  * interested reader.
 169  */
 170 uint16_t generic_tcpip_continue_chksum ( uint16_t partial,
 171                                          const void *data, size_t len ) {
 172         unsigned int cksum = ( ( ~partial ) & 0xffff );
 173         unsigned int value;
 174         unsigned int i;
 175
 176         for ( i = 0 ; i < len ; i++ ) {
 177                 value = * ( ( uint8_t * ) data + i );
 178                 if ( i & 1 ) {
 179                         /* Odd bytes: swap on little-endian systems */
 180                         value = be16_to_cpu ( value );
 181                 } else {
 182                         /* Even bytes: swap on big-endian systems */
 183                         value = le16_to_cpu ( value );
 184                 }
 185                 cksum += value;
 186                 if ( cksum > 0xffff )
 187                         cksum -= 0xffff;
 188         }
 189
 190         return ( ~cksum );
 191 }
 192
 193 /**
 194  * Calculate TCP/IP checkum
 195  *
 196  * @v data              Data buffer
 197  * @v len               Length of data buffer
 198  * @ret cksum           Checksum, in network byte order
 199  *
 200  * Calculates a TCP/IP-style 16-bit checksum over the data block.  The
 201  * checksum is returned in network byte order.
 202  */
 203 uint16_t tcpip_chksum ( const void *data, size_t len ) {
 204         return tcpip_continue_chksum ( TCPIP_EMPTY_CSUM, data, len );
 205 }
 206
 207 /**
 208  * Bind to local TCP/IP port
 209  *
 210  * @v st_local          Local TCP/IP socket address, or NULL
 211  * @v available         Function to check port availability
 212  * @ret port            Local port number, or negative error
 213  */
 214 int tcpip_bind ( struct sockaddr_tcpip *st_local,
 215                  int ( * available ) ( int port ) ) {
 216         uint16_t flags = 0;
 217         uint16_t try_port = 0;
 218         uint16_t min_port;
 219         uint16_t max_port;
 220         unsigned int offset;
 221         unsigned int i;
 222
 223         /* Extract parameters from local socket address */
 224         if ( st_local ) {
 225                 flags = st_local->st_flags;
 226                 try_port = ntohs ( st_local->st_port );
 227         }
 228
 229         /* If an explicit port is specified, check its availability */
 230         if ( try_port )
 231                 return available ( try_port );
 232
 233         /* Otherwise, find an available port in the range [1,1023] or
 234          * [1025,65535] as appropriate.
 235          */
 236         min_port = ( ( ( ~flags ) & TCPIP_BIND_PRIVILEGED ) + 1 );
 237         max_port = ( ( flags & TCPIP_BIND_PRIVILEGED ) - 1 );
 238         offset = random();
 239         for ( i = 0 ; i <= max_port ; i++ ) {
 240                 try_port = ( ( i + offset ) & max_port );
 241                 if ( try_port < min_port )
 242                         continue;
 243                 if ( available ( try_port ) < 0 )
 244                         continue;
 245                 return try_port;
 246         }
 247         return -EADDRINUSE;
 248 }