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A brief file description
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@section license License
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Licensed to the Apache Software Foundation (ASF) under one
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or more contributor license agreements. See the NOTICE file
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distributed with this work for additional information
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regarding copyright ownership. The ASF licenses this file
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to you under the Apache License, Version 2.0 (the
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"License"); you may not use this file except in compliance
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with the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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* response-header-1.c:
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* an example program which illustrates adding and manipulating
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* an HTTP response MIME header:
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* Authorized possession and use of this software pursuant only
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* to the terms of a written license agreement.
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* Usage: response-header-1.so
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* add read_resp_header hook
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* get http response header
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* add mime extension header with count of zero
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* add mime extension header with date response was received
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* add "Cache-Control: public" header
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* retrieve cached header
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* get old value of mime header count
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* increment mime header count
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* store mime header with new count
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static int init_buffer_status;
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static char *mimehdr1_name;
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static char *mimehdr2_name;
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static char *mimehdr1_value;
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static TSMBuffer hdr_bufp;
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static TSMLoc hdr_loc;
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static TSMLoc field_loc;
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static TSMLoc value_loc;
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modify_header(TSHttpTxn txnp, TSCont contp)
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TSMBuffer cached_bufp;
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TSHttpStatus resp_status;
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TSMLoc cached_field_loc;
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int num_refreshes = 0;
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if (!init_buffer_status)
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return; /* caller reenables */
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if (!TSHttpTxnServerRespGet(txnp, &resp_bufp, &resp_loc)) {
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TSError("couldn't retrieve server response header\n");
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return; /* caller reenables */
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/* TSqa06246/TSqa06144 */
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resp_status = TSHttpHdrStatusGet(resp_bufp, resp_loc);
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if (TS_HTTP_STATUS_OK == resp_status) {
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TSDebug("resphdr", "Processing 200 OK");
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new_field_loc = TSMimeHdrFieldCreate(resp_bufp, resp_loc);
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TSDebug("resphdr", "Created new resp field with loc %d", new_field_loc);
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/* copy name/values created at init
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* ( "x-num-served-from-cache" ) : ( "0" )
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TSMimeHdrFieldCopy(resp_bufp, resp_loc, new_field_loc, hdr_bufp, hdr_loc, field_loc);
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/*********** Unclear why this is needed **************/
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TSMimeHdrFieldAppend(resp_bufp, resp_loc, new_field_loc);
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/* Cache-Control: Public */
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new_field_loc = TSMimeHdrFieldCreate(resp_bufp, resp_loc);
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TSDebug("resphdr", "Created new resp field with loc %d", new_field_loc);
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TSMimeHdrFieldAppend(resp_bufp, resp_loc, new_field_loc);
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TSMimeHdrFieldNameSet(resp_bufp, resp_loc, new_field_loc,
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TS_MIME_FIELD_CACHE_CONTROL, TS_MIME_LEN_CACHE_CONTROL);
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TSMimeHdrFieldValueStringInsert(resp_bufp, resp_loc, new_field_loc,
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-1, TS_HTTP_VALUE_PUBLIC, TS_HTTP_LEN_PUBLIC);
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* mimehdr2_name = TSstrdup( "x-date-200-recvd" ) : CurrentDateTime
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new_field_loc = TSMimeHdrFieldCreate(resp_bufp, resp_loc);
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TSDebug("resphdr", "Created new resp field with loc %d", new_field_loc);
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TSMimeHdrFieldAppend(resp_bufp, resp_loc, new_field_loc);
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TSMimeHdrFieldNameSet(resp_bufp, resp_loc, new_field_loc, mimehdr2_name, strlen(mimehdr2_name));
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recvd_time = time(NULL);
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TSMimeHdrFieldValueDateInsert(resp_bufp, resp_loc, new_field_loc, recvd_time);
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TSHandleMLocRelease(resp_bufp, resp_loc, new_field_loc);
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TSHandleMLocRelease(resp_bufp, TS_NULL_MLOC, resp_loc);
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} else if (TS_HTTP_STATUS_NOT_MODIFIED == resp_status) {
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TSDebug("resphdr", "Processing 304 Not Modified");
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/* N.B.: Protect writes to data (hash on URL + mutex: (ies)) */
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/* Get the cached HTTP header */
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if (!TSHttpTxnCachedRespGet(txnp, &cached_bufp, &cached_loc)) {
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TSError("STATUS 304, TSHttpTxnCachedRespGet():");
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TSError("couldn't retrieve cached response header\n");
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TSHandleMLocRelease(resp_bufp, TS_NULL_MLOC, resp_loc);
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return; /* Caller reenables */
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/* Get the cached MIME field name for this HTTP header */
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cached_field_loc = TSMimeHdrFieldFind(cached_bufp, cached_loc,
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(const char *) mimehdr1_name, strlen(mimehdr1_name));
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if (0 == cached_field_loc) {
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TSError("Can't find header %s in cached document", mimehdr1_name);
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TSHandleMLocRelease(resp_bufp, TS_NULL_MLOC, resp_loc);
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TSHandleMLocRelease(cached_bufp, TS_NULL_MLOC, cached_loc);
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return; /* Caller reenables */
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/* Get the cached MIME value for this name in this HTTP header */
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if (TSMimeHdrFieldValueStringGet(cached_bufp, cached_loc, cached_field_loc, 0, &chkptr, &chklength) == TS_ERROR ||
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NULL == chkptr || !chklength) {
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TSError("Could not find value for cached MIME field name %s", mimehdr1_name);
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TSHandleMLocRelease(resp_bufp, TS_NULL_MLOC, resp_loc);
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TSHandleMLocRelease(cached_bufp, TS_NULL_MLOC, cached_loc);
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TSHandleMLocRelease(cached_bufp, cached_loc, cached_field_loc);
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return; /* Caller reenables */
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TSDebug("resphdr", "Header field value is %s, with length %d", chkptr, chklength);
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/* TODO check these comments for correctness */
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* Since TSMimeHdrFieldValueStringGet returned with valid values
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* are we also guaranteed that TSMimeHdrFieldValueUintGet returns
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* valid values? There is no erro code for TSMimeHdrFieldValueUintGet
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* and 0 is a valid value.
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/* Get the cached MIME value for this name in this HTTP header */
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TSMimeHdrFieldValueUintGet(cached_bufp, cached_loc, cached_field_loc, 0, &num_refreshes);
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"Cached header shows %d refreshes so far", num_refreshes );
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/* txn origin server response for this transaction stored
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* in resp_bufp, resp_loc
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* Create a new MIME field/value. Cached value has been incremented.
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* Insert new MIME field/value into the server response buffer,
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* allow HTTP processing to continue. This will update
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* (indirectly invalidates) the cached HTTP headers MIME field.
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* It is apparently not necessary to update all of the MIME fields
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* in the in-process response in order to have the cached response
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new_field_loc = TSMimeHdrFieldCreate(resp_bufp, resp_loc);
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/* mimehdr1_name : TSstrdup( "x-num-served-from-cache" ) ; */
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TSMimeHdrFieldAppend(resp_bufp, resp_loc, new_field_loc);
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TSMimeHdrFieldNameSet(resp_bufp, resp_loc, new_field_loc, mimehdr1_name, strlen(mimehdr1_name));
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TSMimeHdrFieldValueUintInsert(resp_bufp, resp_loc, new_field_loc, -1, num_refreshes);
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TSHandleMLocRelease(resp_bufp, resp_loc, new_field_loc);
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TSHandleMLocRelease(cached_bufp, cached_loc, cached_field_loc);
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TSHandleMLocRelease(cached_bufp, TS_NULL_MLOC, cached_loc);
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TSHandleMLocRelease(resp_bufp, TS_NULL_MLOC, resp_loc);
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TSDebug("resphdr", "other response code %d", resp_status);
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* Additional 200/304 processing can go here, if so desired.
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/* Caller reneables */
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modify_response_header_plugin(TSCont contp, TSEvent event, void *edata)
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TSHttpTxn txnp = (TSHttpTxn) edata;
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case TS_EVENT_HTTP_READ_RESPONSE_HDR:
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TSDebug("resphdr", "Called back with TS_EVENT_HTTP_READ_RESPONSE_HDR");
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modify_header(txnp, contp);
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TSHttpTxnReenable(txnp, TS_EVENT_HTTP_CONTINUE);
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const char *ts_version = TSTrafficServerVersionGet();
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int major_ts_version = 0;
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int minor_ts_version = 0;
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int patch_ts_version = 0;
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if (sscanf(ts_version, "%d.%d.%d", &major_ts_version, &minor_ts_version, &patch_ts_version) != 3) {
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/* Need at least TS 2.0 */
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if (major_ts_version >= 2) {
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TSPluginInit(int argc, const char *argv[])
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TSMLoc chk_field_loc;
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TSPluginRegistrationInfo info;
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info.plugin_name = "response-header-1";
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info.vendor_name = "MyCompany";
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info.support_email = "ts-api-support@MyCompany.com";
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if (!TSPluginRegister(TS_SDK_VERSION_3_0, &info)) {
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TSError("Plugin registration failed.\n");
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if (!check_ts_version()) {
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TSError("Plugin requires Traffic Server 3.0 or later\n");
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init_buffer_status = 0;
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TSError("usage: %s \n", argv[0]);
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TSError("warning: too many args %d\n", argc);
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TSError("warning: ignoring unused arguments beginning with %s\n", argv[1]);
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* The following code sets up an "init buffer" containing an extension header
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* and its initial value. This will be the same for all requests, so we try
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* to be efficient and do all of the work here rather than on a per-transaction
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hdr_bufp = TSMBufferCreate();
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hdr_loc = TSMimeHdrCreate(hdr_bufp);
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mimehdr1_name = TSstrdup("x-num-served-from-cache");
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mimehdr1_value = TSstrdup("0");
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/* Create name here and set DateTime value when o.s.
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* response 200 is received
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mimehdr2_name = TSstrdup("x-date-200-recvd");
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TSDebug("resphdr", "Inserting header %s with value %s into init buffer", mimehdr1_name, mimehdr1_value);
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field_loc = TSMimeHdrFieldCreate(hdr_bufp, hdr_loc);
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TSMimeHdrFieldAppend(hdr_bufp, hdr_loc, field_loc);
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TSMimeHdrFieldNameSet(hdr_bufp, hdr_loc, field_loc, mimehdr1_name, strlen(mimehdr1_name));
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TSMimeHdrFieldValueStringInsert(hdr_bufp, hdr_loc, field_loc, -1, mimehdr1_value, strlen(mimehdr1_value));
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TSDebug("resphdr", "init buffer hdr, field and value locs are %d, %d and %d", hdr_loc, field_loc, value_loc);
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init_buffer_status = 1;
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TSHttpHookAdd(TS_HTTP_READ_RESPONSE_HDR_HOOK, TSContCreate(modify_response_header_plugin, NULL));
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* The following code demonstrates how to extract the field_loc from the header.
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* In this plugin, the init buffer and thus field_loc never changes. Code
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* similar to this may be used to extract header fields from any buffer.
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if (0 == (chk_field_loc = TSMimeHdrFieldGet(hdr_bufp, hdr_loc, 0))) {
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TSError("couldn't retrieve header field from init buffer");
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TSError("marking init buffer as corrupt; no more plugin processing");
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init_buffer_status = 0;
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/* bail out here and reenable transaction */
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if (field_loc != chk_field_loc)
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TSError("retrieved buffer field loc is %d when it should be %d", chk_field_loc, field_loc);
added
removed
example/response-header-1/response-header-1.c
