svn commit: r929213 - in /incubator/trafficserver/traffic/trunk/example/query_remap: ./ query_remap.c

[sj...@apache.org]

Author: sjiang
Date: Tue Mar 30 18:22:25 2010
New Revision: 929213

URL: http://svn.apache.org/viewvc?rev=929213&view=rev
Log:
TS-270: code for example in chapter 3

Added:
    incubator/trafficserver/traffic/trunk/example/query_remap/
    incubator/trafficserver/traffic/trunk/example/query_remap/query_remap.c

Added: incubator/trafficserver/traffic/trunk/example/query_remap/query_remap.c
URL: http://svn.apache.org/viewvc/incubator/trafficserver/traffic/trunk/example/query_remap/query_remap.c?rev=929213&view=auto
==============================================================================
--- incubator/trafficserver/traffic/trunk/example/query_remap/query_remap.c (added)
+++ incubator/trafficserver/traffic/trunk/example/query_remap/query_remap.c Tue Mar 30 18:22:25 2010
@@ -0,0 +1,179 @@
+/** @file
+
+  A sample plugin to remap requests based on a query parameter
+
+  @section license License
+
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#include <ts/remap.h>
+#include <ts/ts.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define PLUGIN_NAME "query_remap"
+
+//function prototypes
+u_int32_t hash_fnv32(char *buf, size_t len);
+
+typedef struct _query_remap_info {
+  char *param_name;
+  size_t param_len;
+  char **hosts;
+  int num_hosts;
+} query_remap_info;
+
+
+int tsremap_init(TSRemapInterface *api_info,char *errbuf,int errbuf_size)
+{
+// Called at TS startup. Nothing needed for this plugin
+  INKDebug(PLUGIN_NAME , "remap plugin initialized");
+  return 0;
+}
+
+
+int tsremap_new_instance(int argc,char *argv[],ihandle *ih,char *errbuf,int errbuf_size)
+{
+// Called for each remap rule using this plugin. The parameters are parsed here
+  int i;
+  INKDebug(PLUGIN_NAME, "new instance fromURL: %s toURL: %s", argv[0], argv[1]);
+
+  if (argc < 4) {
+    INKError("Missing parameters for " PLUGIN_NAME);
+    return -1;
+  }
+
+  //initialize the struct to store info about this remap instance
+  // the argv parameters are:
+  // 0: fromURL
+  // 1: toURL
+  // 2: query param to hash
+  // 3,4,... : server hostnames
+  query_remap_info *qri = (query_remap_info*) malloc(sizeof(query_remap_info));
+  
+  qri->param_name = strdup(argv[2]);
+  qri->param_len = strlen(qri->param_name);
+  qri->num_hosts = argc - 3;
+  qri->hosts = (char**) malloc(qri->num_hosts*sizeof(char*));
+
+  INKDebug(PLUGIN_NAME, " - Hash using query parameter [%s] with %d hosts", 
+           qri->param_name, qri->num_hosts);  
+
+  for (i=0; i < qri->num_hosts; ++i) {
+    qri->hosts[i] = strdup(argv[i+3]);
+    INKDebug(PLUGIN_NAME, " - Host %d: %s", i, qri->hosts[i]);
+  }
+  
+  *ih = (ihandle)qri;
+  INKDebug(PLUGIN_NAME, "created instance %p", *ih);
+  return 0;
+}
+
+void tsremap_delete_instance(ihandle ih)
+{
+// Release instance memory allocated in tsremap_new_instance
+  int i;
+  INKDebug(PLUGIN_NAME, "deleting instance %p", ih);
+
+  if (ih) {
+    query_remap_info *qri = (query_remap_info*)ih;
+    if (qri->param_name) 
+      free(qri->param_name);
+    if (qri->hosts) {
+      for (i=0; i < qri->num_hosts; ++i) {
+        free(qri->hosts[i]);
+      }
+      free(qri->hosts);        
+    }
+    free(qri);
+  }
+}
+
+
+int tsremap_remap(ihandle ih, rhandle rh, TSRemapRequestInfo *rri)
+{
+  int hostidx = -1;
+  query_remap_info *qri = (query_remap_info*)ih;
+
+  if (!qri) {
+    INKError(PLUGIN_NAME "NULL ihandle");
+    return 0;
+  }
+
+  INKDebug(PLUGIN_NAME, "tsremap_remap request: %.*s", rri->orig_url_size, rri->orig_url);
+  
+  if (rri && rri->request_query && rri->request_query_size > 0) {
+    char *q, *s, *key;
+
+    //make a copy of the query, as it is read only
+    q = (char*) malloc(rri->request_query_size+1);
+    strncpy(q, rri->request_query, rri->request_query_size);
+    q[rri->request_query_size] = '\0';
+
+    s = q;
+    //parse query parameters
+    for (key = strsep(&s, "&"); key != NULL; key = strsep(&s, "&")) {
+      char *val = strchr(key, '=');
+      if (val && (size_t)(val-key) == qri->param_len && 
+          !strncmp(key, qri->param_name, qri->param_len)) {
+        ++val;
+        //the param key matched the configured param_name
+        //hash the param value to pick a host
+        hostidx = hash_fnv32(val, strlen(val)) % (u_int32_t)qri->num_hosts;
+        INKDebug(PLUGIN_NAME, "modifying host based on %s", key);
+        break;
+      }
+    }
+    
+    free(q);
+
+    if (hostidx >= 0) {
+      rri->new_host_size = strlen(qri->hosts[hostidx]);
+      if (rri->new_host_size <= TSREMAP_RRI_MAX_HOST_SIZE) {
+        //copy the chosen host into rri
+        memcpy(rri->new_host, qri->hosts[hostidx], rri->new_host_size);
+
+        INKDebug(PLUGIN_NAME, "host changed from [%.*s] to [%.*s]", 
+                 rri->request_host_size, rri->request_host,
+                 rri->new_host_size, rri->new_host);
+        return 1; //host has been modified
+      }
+    }
+  }
+    
+  //the request was not modified, TS will use the toURL from the remap rule
+  INKDebug(PLUGIN_NAME, "request not modified");  
+  return 0;
+}
+
+
+// FNV (Fowler/Noll/Vo) hash
+// (description: http://www.isthe.com/chongo/tech/comp/fnv/index.html)
+u_int32_t 
+hash_fnv32(char *buf, size_t len)
+{
+  u_int32_t hval = (u_int32_t)0x811c9dc5; //FNV1_32_INIT
+
+  for (; len > 0; --len) {
+    hval *= (u_int32_t)0x01000193; //FNV_32_PRIME
+    hval ^= (u_int32_t)*buf++;
+  }
+
+  return hval;
+}
+