KernelLand/Modules/IPStack/buffer.c

   1 /*
   2  * Acess2 Networking Stack
   3  * - By John Hodge (thePowersGang)
   4  *
   5  * buffer.c
   6  * - Scatter-gather handling
   7  */
   8 #include "ipstack.h"
   9 #include "include/buffer.h"
  10
  11 // === STRUCTURES ===
  12 struct sIPStackBuffer
  13 {
  14          int    MaxSubBufffers;
  15          int    nSubBuffers;
  16         size_t  TotalLength;
  17         struct _subbuffer
  18         {
  19                 const void      *Data;
  20                 size_t  PreLength;
  21                 size_t  PostLength;
  22                 tIPStackBufferCb        Cb;
  23                 void    *CbArg;
  24                 // TODO: Callbacks?
  25         } SubBuffers[];
  26 };
  27
  28 // === CODE ===
  29 tIPStackBuffer *IPStack_Buffer_CreateBuffer(int MaxBuffers)
  30 {
  31         tIPStackBuffer *ret;
  32
  33         ret = malloc( sizeof(*ret) + MaxBuffers * sizeof(ret->SubBuffers[0]) );
  34         ret->MaxSubBufffers = MaxBuffers;
  35         ret->nSubBuffers = 0;
  36         ret->TotalLength = 0;
  37         memset(ret->SubBuffers, 0, MaxBuffers * sizeof(ret->SubBuffers[0]));
  38         return ret;
  39 }
  40
  41 void IPStack_Buffer_ClearBuffer(tIPStackBuffer *Buffer)
  42 {
  43         for( int i = 0; i < Buffer->nSubBuffers; i ++ )
  44         {
  45                 if( Buffer->SubBuffers[i].Cb == NULL )
  46                         continue ;
  47                 Buffer->SubBuffers[i].Cb(
  48                         Buffer->SubBuffers[i].CbArg,
  49                         Buffer->SubBuffers[i].PreLength,
  50                         Buffer->SubBuffers[i].PostLength,
  51                         Buffer->SubBuffers[i].Data
  52                         );
  53         }
  54         // TODO: Fire callbacks?
  55         Buffer->nSubBuffers = 0;
  56 }
  57
  58 void IPStack_Buffer_DestroyBuffer(tIPStackBuffer *Buffer)
  59 {
  60         IPStack_Buffer_ClearBuffer(Buffer);
  61         Buffer->MaxSubBufffers = 0;
  62         free(Buffer);
  63 }
  64
  65 void IPStack_Buffer_AppendSubBuffer(tIPStackBuffer *Buffer,
  66         size_t HeaderLen, size_t FooterLen, const void *Data,
  67         tIPStackBufferCb Cb, void *Arg
  68         )
  69 {
  70         if( Buffer->nSubBuffers == Buffer->MaxSubBufffers ) {
  71                 // Ah, oops?
  72                 Log_Error("IPStack", "Buffer %p only had %i sub-buffers allocated, which was not enough",
  73                         Buffer, Buffer->MaxSubBufffers);
  74                 return ;
  75         }
  76
  77         int index = Buffer->nSubBuffers++;
  78         Buffer->TotalLength += HeaderLen + FooterLen;
  79
  80         Buffer->SubBuffers[index].Data = Data;
  81         Buffer->SubBuffers[index].PreLength = HeaderLen;
  82         Buffer->SubBuffers[index].PostLength = FooterLen;
  83         Buffer->SubBuffers[index].Cb = Cb;
  84         Buffer->SubBuffers[index].CbArg = Arg;
  85 }
  86
  87 size_t IPStack_Buffer_GetLength(tIPStackBuffer *Buffer)
  88 {
  89         return Buffer->TotalLength;
  90 }
  91
  92 size_t IPStack_Buffer_GetData(tIPStackBuffer *Buffer, void *Dest, size_t MaxBytes)
  93 {
  94         Uint8   *dest = Dest;
  95         size_t  rem_space = MaxBytes;
  96         size_t  len;
  97
  98         for( int i = Buffer->nSubBuffers; i -- && rem_space != 0; )
  99         {
 100                 len = MIN(Buffer->SubBuffers[i].PreLength, rem_space);
 101                 memcpy(dest,
 102                         Buffer->SubBuffers[i].Data,
 103                         len
 104                         );
 105                 dest += len;
 106                 rem_space -= len;
 107         }
 108         for( int i = 0; i < Buffer->nSubBuffers && rem_space; i ++ )
 109         {
 110                 if( Buffer->SubBuffers[i].PostLength == 0  )
 111                         continue ;
 112
 113                 len = MIN(Buffer->SubBuffers[i].PostLength, rem_space);
 114                 memcpy(dest,
 115                         (Uint8*)Buffer->SubBuffers[i].Data + Buffer->SubBuffers[i].PreLength,
 116                         len
 117                         );
 118                 dest += len;
 119                 rem_space -= len;
 120         }
 121
 122         return MaxBytes - rem_space;
 123 }
 124
 125 void *IPStack_Buffer_CompactBuffer(tIPStackBuffer *Buffer, size_t *Length)
 126 {
 127         void    *ret;
 128
 129         ret = malloc(Buffer->TotalLength);
 130         if(!ret) {
 131                 *Length = 0;
 132                 return NULL;
 133         }
 134
 135         *Length = Buffer->TotalLength;
 136
 137         IPStack_Buffer_GetData(Buffer, ret, Buffer->TotalLength);
 138
 139         return ret;
 140 }
 141
 142 int IPStack_Buffer_GetBuffer(tIPStackBuffer *Buffer, int Index, size_t *Length, const void **DataPtr)
 143 {
 144         if( Index == -1 )       Index = 0;
 145
 146         if( Index >= Buffer->nSubBuffers*2 ) {
 147                 return -1;
 148         }
 149
 150         if( Index > Buffer->nSubBuffers )
 151         {
 152                 // Appended buffers
 153                 Index -= Buffer->nSubBuffers;
 154
 155                 // Bit of a hack to avoid multiple calls which return a zero length
 156                 while( !Buffer->SubBuffers[Index].PostLength )
 157                 {
 158                         if( Index++ == Buffer->nSubBuffers )
 159                                 return -1;
 160                 }
 161
 162                 *DataPtr = (Uint8*)Buffer->SubBuffers[Index].Data + Buffer->SubBuffers[Index].PreLength;
 163                 *Length = Buffer->SubBuffers[Index].PostLength;
 164
 165                 return (Index + 1) + Buffer->nSubBuffers;
 166         }
 167         else
 168         {
 169                 Index = Buffer->nSubBuffers - Index;
 170                 // Prepended buffers
 171                 *DataPtr = Buffer->SubBuffers[Index].Data;
 172                 *Length = Buffer->SubBuffers[Index].PreLength;
 173                 return Buffer->nSubBuffers - (Index - 1);
 174         }
 175 }
 176