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         tMutex  lBufferLock;
  18
  19         struct _subbuffer
  20         {
  21                 const void      *Data;
  22                 size_t  PreLength;
  23                 size_t  PostLength;
  24                 tIPStackBufferCb        Cb;
  25                 void    *CbArg;
  26                 // TODO: Callbacks?
  27         } SubBuffers[];
  28 };
  29
  30 // === CODE ===
  31 tIPStackBuffer *IPStack_Buffer_CreateBuffer(int MaxBuffers)
  32 {
  33         tIPStackBuffer *ret;
  34
  35         ret = malloc( sizeof(*ret) + MaxBuffers * sizeof(ret->SubBuffers[0]) );
  36         ret->MaxSubBufffers = MaxBuffers;
  37         ret->nSubBuffers = 0;
  38         ret->TotalLength = 0;
  39         memset(&ret->lBufferLock, 0, sizeof(ret->lBufferLock));
  40         memset(ret->SubBuffers, 0, MaxBuffers * sizeof(ret->SubBuffers[0]));
  41         return ret;
  42 }
  43
  44 void IPStack_Buffer_ClearBuffer(tIPStackBuffer *Buffer)
  45 {
  46         IPStack_Buffer_LockBuffer(Buffer);
  47         for( int i = 0; i < Buffer->nSubBuffers; i ++ )
  48         {
  49                 if( Buffer->SubBuffers[i].Cb == NULL )
  50                         continue ;
  51                 Buffer->SubBuffers[i].Cb(
  52                         Buffer->SubBuffers[i].CbArg,
  53                         Buffer->SubBuffers[i].PreLength,
  54                         Buffer->SubBuffers[i].PostLength,
  55                         Buffer->SubBuffers[i].Data
  56                         );
  57         }
  58         Buffer->nSubBuffers = 0;
  59         IPStack_Buffer_UnlockBuffer(Buffer);
  60 }
  61
  62 void IPStack_Buffer_DestroyBuffer(tIPStackBuffer *Buffer)
  63 {
  64         IPStack_Buffer_ClearBuffer(Buffer);
  65         Buffer->MaxSubBufffers = 0;
  66         free(Buffer);
  67 }
  68
  69 void IPStack_Buffer_LockBuffer(tIPStackBuffer *Buffer)
  70 {
  71         Mutex_Acquire(&Buffer->lBufferLock);
  72 }
  73 void IPStack_Buffer_UnlockBuffer(tIPStackBuffer *Buffer)
  74 {
  75         Mutex_Release(&Buffer->lBufferLock);
  76 }
  77
  78 void IPStack_Buffer_AppendSubBuffer(tIPStackBuffer *Buffer,
  79         size_t HeaderLen, size_t FooterLen, const void *Data,
  80         tIPStackBufferCb Cb, void *Arg
  81         )
  82 {
  83         if( Buffer->nSubBuffers == Buffer->MaxSubBufffers ) {
  84                 // Ah, oops?
  85                 Log_Error("IPStack", "Buffer %p only had %i sub-buffers allocated, which was not enough",
  86                         Buffer, Buffer->MaxSubBufffers);
  87                 return ;
  88         }
  89
  90         int index = Buffer->nSubBuffers++;
  91         Buffer->TotalLength += HeaderLen + FooterLen;
  92
  93         Buffer->SubBuffers[index].Data = Data;
  94         Buffer->SubBuffers[index].PreLength = HeaderLen;
  95         Buffer->SubBuffers[index].PostLength = FooterLen;
  96         Buffer->SubBuffers[index].Cb = Cb;
  97         Buffer->SubBuffers[index].CbArg = Arg;
  98 }
  99
 100 size_t IPStack_Buffer_GetLength(tIPStackBuffer *Buffer)
 101 {
 102         return Buffer->TotalLength;
 103 }
 104
 105 size_t IPStack_Buffer_GetData(tIPStackBuffer *Buffer, void *Dest, size_t MaxBytes)
 106 {
 107         Uint8   *dest = Dest;
 108         size_t  rem_space = MaxBytes;
 109         size_t  len;
 110
 111         for( int i = Buffer->nSubBuffers; i -- && rem_space != 0; )
 112         {
 113                 len = MIN(Buffer->SubBuffers[i].PreLength, rem_space);
 114                 memcpy(dest,
 115                         Buffer->SubBuffers[i].Data,
 116                         len
 117                         );
 118                 dest += len;
 119                 rem_space -= len;
 120         }
 121         for( int i = 0; i < Buffer->nSubBuffers && rem_space; i ++ )
 122         {
 123                 if( Buffer->SubBuffers[i].PostLength == 0  )
 124                         continue ;
 125
 126                 len = MIN(Buffer->SubBuffers[i].PostLength, rem_space);
 127                 memcpy(dest,
 128                         (Uint8*)Buffer->SubBuffers[i].Data + Buffer->SubBuffers[i].PreLength,
 129                         len
 130                         );
 131                 dest += len;
 132                 rem_space -= len;
 133         }
 134
 135         return MaxBytes - rem_space;
 136 }
 137
 138 void *IPStack_Buffer_CompactBuffer(tIPStackBuffer *Buffer, size_t *Length)
 139 {
 140         void    *ret;
 141
 142         ret = malloc(Buffer->TotalLength);
 143         if(!ret) {
 144                 *Length = 0;
 145                 return NULL;
 146         }
 147
 148         *Length = Buffer->TotalLength;
 149
 150         IPStack_Buffer_GetData(Buffer, ret, Buffer->TotalLength);
 151
 152         return ret;
 153 }
 154
 155 int IPStack_Buffer_GetBuffer(tIPStackBuffer *Buffer, int Index, size_t *Length, const void **DataPtr)
 156 {
 157         if( Index == -1 )       Index = 0;
 158
 159         if( Index >= Buffer->nSubBuffers*2 ) {
 160                 return -1;
 161         }
 162
 163         if( Index >= Buffer->nSubBuffers )
 164         {
 165                 // Appended buffers
 166                 Index -= Buffer->nSubBuffers;
 167
 168                 // Bit of a hack to avoid multiple calls which return a zero length
 169                 while( !Buffer->SubBuffers[Index].PostLength )
 170                 {
 171                         if( Index++ == Buffer->nSubBuffers )
 172                                 return -1;
 173                 }
 174
 175                 *DataPtr = (Uint8*)Buffer->SubBuffers[Index].Data + Buffer->SubBuffers[Index].PreLength;
 176                 *Length = Buffer->SubBuffers[Index].PostLength;
 177
 178                 return (Index + 1) + Buffer->nSubBuffers;
 179         }
 180         else
 181         {
 182                  int    rv = Index + 1;
 183                 Index = Buffer->nSubBuffers - Index - 1;
 184                 // Prepended buffers
 185                 *DataPtr = Buffer->SubBuffers[Index].Data;
 186                 *Length = Buffer->SubBuffers[Index].PreLength;
 187                 return rv;
 188         }
 189 }
 190