git.m6w6.name Git - awesomized/libmemcached/blob - libmemcached/protocol/protocol_handler.c

   1 /* -*- Mode: C; tab-width: 2; c-basic-offset: 2; indent-tabs-mode: nil -*- */
   2 #include "libmemcached/protocol/common.h"
   3
   4 #include <stdlib.h>
   5 #include <sys/types.h>
   6 #include <sys/socket.h>
   7 #include <errno.h>
   8 #include <stdbool.h>
   9 #include <string.h>
  10 #include <strings.h>
  11 #include <ctype.h>
  12 #include <stdio.h>
  13
  14 /*
  15 ** **********************************************************************
  16 ** INTERNAL INTERFACE
  17 ** **********************************************************************
  18 */
  19
  20 /**
  21  * The default function to receive data from the client. This function
  22  * just wraps the recv function to receive from a socket.
  23  * See man -s3socket recv for more information.
  24  *
  25  * @param cookie cookie indentifying a client, not used
  26  * @param sock socket to read from
  27  * @param buf the destination buffer
  28  * @param nbytes the number of bytes to read
  29  * @return the number of bytes transferred of -1 upon error
  30  */
  31 static ssize_t default_recv(const void *cookie,
  32                             int sock,
  33                             void *buf,
  34                             size_t nbytes)
  35 {
  36   (void)cookie;
  37   return recv(sock, buf, nbytes, 0);
  38 }
  39
  40 /**
  41  * The default function to send data to the server. This function
  42  * just wraps the send function to send through a socket.
  43  * See man -s3socket send for more information.
  44  *
  45  * @param cookie cookie indentifying a client, not used
  46  * @param sock socket to send to
  47  * @param buf the source buffer
  48  * @param nbytes the number of bytes to send
  49  * @return the number of bytes transferred of -1 upon error
  50  */
  51 static ssize_t default_send(const void *cookie,
  52                             int fd,
  53                             const void *buf,
  54                             size_t nbytes)
  55 {
  56   (void)cookie;
  57   return send(fd, buf, nbytes, 0);
  58 }
  59
  60 /**
  61  * Try to drain the output buffers without blocking
  62  *
  63  * @param client the client to drain
  64  * @return false if an error occured (connection should be shut down)
  65  *         true otherwise (please note that there may be more data to
  66  *              left in the buffer to send)
  67  */
  68 static bool drain_output(struct memcached_protocol_client_st *client)
  69 {
  70   ssize_t len;
  71
  72   /* Do we have pending data to send? */
  73   while (client->output != NULL)
  74   {
  75     len= client->root->send(client,
  76                             client->sock,
  77                             client->output->data + client->output->offset,
  78                             client->output->nbytes - client->output->offset);
  79
  80     if (len == -1)
  81     {
  82       if (errno == EWOULDBLOCK)
  83       {
  84         return true;
  85       }
  86       else if (errno != EINTR)
  87       {
  88         client->error= errno;
  89         return false;
  90       }
  91     }
  92     else
  93     {
  94       client->output->offset += (size_t)len;
  95       if (client->output->offset == client->output->nbytes)
  96       {
  97         /* This was the complete buffer */
  98         struct chunk_st *old= client->output;
  99         client->output= client->output->next;
 100         if (client->output == NULL)
 101         {
 102           client->output_tail= NULL;
 103         }
 104         cache_free(client->root->buffer_cache, old);
 105       }
 106     }
 107   }
 108
 109   return true;
 110 }
 111
 112 /**
 113  * Allocate an output buffer and chain it into the output list
 114  *
 115  * @param client the client that needs the buffer
 116  * @return pointer to the new chunk if the allocation succeeds, NULL otherwise
 117  */
 118 static struct chunk_st *allocate_output_chunk(struct memcached_protocol_client_st *client)
 119 {
 120   struct chunk_st *ret= cache_alloc(client->root->buffer_cache);
 121   if (ret == NULL)
 122   {
 123     return NULL;
 124   }
 125
 126   ret->offset = ret->nbytes = 0;
 127   ret->next = NULL;
 128   ret->size = CHUNK_BUFFERSIZE;
 129   ret->data= (void*)(ret + 1);
 130   if (client->output == NULL)
 131   {
 132     client->output = client->output_tail = ret;
 133   }
 134   else
 135   {
 136     client->output_tail->next= ret;
 137     client->output_tail= ret;
 138   }
 139
 140   return ret;
 141 }
 142
 143 /**
 144  * Spool data into the send-buffer for a client.
 145  *
 146  * @param client the client to spool the data for
 147  * @param data the data to spool
 148  * @param length the number of bytes of data to spool
 149  * @return PROTOCOL_BINARY_RESPONSE_SUCCESS if success,
 150  *         PROTOCOL_BINARY_RESPONSE_ENOMEM if we failed to allocate memory
 151  */
 152 static protocol_binary_response_status spool_output(struct memcached_protocol_client_st *client,
 153                                                     const void *data,
 154                                                     size_t length)
 155 {
 156   if (client->mute)
 157   {
 158     return PROTOCOL_BINARY_RESPONSE_SUCCESS;
 159   }
 160
 161   size_t offset = 0;
 162
 163   struct chunk_st *chunk= client->output;
 164   while (offset < length)
 165   {
 166     if (chunk == NULL || (chunk->size - chunk->nbytes) == 0)
 167     {
 168       if ((chunk= allocate_output_chunk(client)) == NULL)
 169       {
 170         return PROTOCOL_BINARY_RESPONSE_ENOMEM;
 171       }
 172     }
 173
 174     size_t bulk = length - offset;
 175     if (bulk > chunk->size - chunk->nbytes)
 176     {
 177       bulk = chunk->size - chunk->nbytes;
 178     }
 179
 180     memcpy(chunk->data + chunk->nbytes, data, bulk);
 181     chunk->nbytes += bulk;
 182     offset += bulk;
 183   }
 184
 185   return PROTOCOL_BINARY_RESPONSE_SUCCESS;
 186 }
 187
 188 /**
 189  * Try to determine the protocol used on this connection.
 190  * If the first byte contains the magic byte PROTOCOL_BINARY_REQ we should
 191  * be using the binary protocol on the connection. I implemented the support
 192  * for the ASCII protocol by wrapping into the simple interface (aka v1),
 193  * so the implementors needs to provide an implementation of that interface
 194  *
 195  */
 196 static enum MEMCACHED_PROTOCOL_EVENT determine_protocol(struct memcached_protocol_client_st *client, ssize_t *length, void **endptr)
 197 {
 198   if (*client->root->input_buffer == (uint8_t)PROTOCOL_BINARY_REQ)
 199   {
 200     client->work= memcached_binary_protocol_process_data;
 201   }
 202   else if (client->root->callback->interface_version == 1)
 203   {
 204     /*
 205      * The ASCII protocol can only be used if the implementors provide
 206      * an implementation for the version 1 of the interface..
 207      *
 208      * @todo I should allow the implementors to provide an implementation
 209      *       for version 0 and 1 at the same time and set the preferred
 210      *       interface to use...
 211      */
 212     client->work= memcached_ascii_protocol_process_data;
 213   }
 214   else
 215   {
 216     /* Let's just output a warning the way it is supposed to look like
 217      * in the ASCII protocol...
 218      */
 219     const char *err= "CLIENT_ERROR: Unsupported protocol\r\n";
 220     client->root->spool(client, err, strlen(err));
 221     client->root->drain(client);
 222     return ERROR_EVENT; /* Unsupported protocol */
 223   }
 224
 225   return client->work(client, length, endptr);
 226 }
 227
 228 /*
 229 ** **********************************************************************
 230 ** * PUBLIC INTERFACE
 231 ** * See protocol_handler.h for function description
 232 ** **********************************************************************
 233 */
 234 struct memcached_protocol_st *memcached_protocol_create_instance(void)
 235 {
 236   struct memcached_protocol_st *ret= calloc(1, sizeof(*ret));
 237   if (ret != NULL)
 238   {
 239     ret->recv= default_recv;
 240     ret->send= default_send;
 241     ret->drain= drain_output;
 242     ret->spool= spool_output;
 243     ret->input_buffer_size= 1 * 1024 * 1024;
 244     ret->input_buffer= malloc(ret->input_buffer_size);
 245     if (ret->input_buffer == NULL)
 246     {
 247       free(ret);
 248       ret= NULL;
 249       return NULL;
 250     }
 251
 252     ret->buffer_cache = cache_create("protocol_handler",
 253                                      CHUNK_BUFFERSIZE + sizeof(struct chunk_st),
 254                                      0, NULL, NULL);
 255     if (ret->buffer_cache == NULL) {
 256       free(ret->input_buffer);
 257       free(ret);
 258     }
 259   }
 260
 261   return ret;
 262 }
 263
 264 void memcached_protocol_destroy_instance(struct memcached_protocol_st *instance)
 265 {
 266   cache_destroy(instance->buffer_cache);
 267   free(instance->input_buffer);
 268   free(instance);
 269 }
 270
 271 struct memcached_protocol_client_st *memcached_protocol_create_client(struct memcached_protocol_st *instance, int sock)
 272 {
 273   struct memcached_protocol_client_st *ret= calloc(1, sizeof(*ret));
 274   if (ret != NULL)
 275   {
 276     ret->root= instance;
 277     ret->sock= sock;
 278     ret->work= determine_protocol;
 279   }
 280
 281   return ret;
 282 }
 283
 284 void memcached_protocol_client_destroy(struct memcached_protocol_client_st *client)
 285 {
 286   free(client);
 287 }
 288
 289 enum MEMCACHED_PROTOCOL_EVENT memcached_protocol_client_work(struct memcached_protocol_client_st *client)
 290 {
 291   /* Try to send data and read from the socket */
 292   bool more_data= true;
 293   do
 294   {
 295     ssize_t len= client->root->recv(client,
 296                                     client->sock,
 297                                     client->root->input_buffer + client->input_buffer_offset,
 298                                     client->root->input_buffer_size - client->input_buffer_offset);
 299
 300     if (len > 0)
 301     {
 302       /* Do we have the complete packet? */
 303       if (client->input_buffer_offset > 0)
 304       {
 305         memcpy(client->root->input_buffer, client->input_buffer,
 306                client->input_buffer_offset);
 307         len += (ssize_t)client->input_buffer_offset;
 308
 309         /* @todo use buffer-cache! */
 310         free(client->input_buffer);
 311         client->input_buffer_offset= 0;
 312       }
 313
 314       void *endptr;
 315       if (client->work(client, &len, &endptr) == ERROR_EVENT)
 316       {
 317         return ERROR_EVENT;
 318       }
 319
 320       if (len > 0)
 321       {
 322         /* save the data for later on */
 323         /* @todo use buffer-cache */
 324         client->input_buffer= malloc((size_t)len);
 325         if (client->input_buffer == NULL)
 326         {
 327           client->error= ENOMEM;
 328           return ERROR_EVENT;
 329         }
 330         memcpy(client->input_buffer, endptr, (size_t)len);
 331         client->input_buffer_offset= (size_t)len;
 332         more_data= false;
 333       }
 334     }
 335     else if (len == 0)
 336     {
 337       /* Connection closed */
 338       drain_output(client);
 339       return ERROR_EVENT;
 340     }
 341     else
 342     {
 343       if (errno != EWOULDBLOCK)
 344       {
 345         client->error= errno;
 346         /* mark this client as terminated! */
 347         return ERROR_EVENT;
 348       }
 349       more_data = false;
 350     }
 351   } while (more_data);
 352
 353   if (!drain_output(client))
 354   {
 355     return ERROR_EVENT;
 356   }
 357
 358   return (client->output) ? READ_WRITE_EVENT : READ_EVENT;
 359 }