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/** @file
This plugin enables validation of link by performing checksum computations.
@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 <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <openssl/md5.h> // For MD5_DIGEST_LENGTH
#include <openssl/evp.h>
#include "ts/ts.h"
#include "ts/remap.h"
#define PLUGIN_NAME "secure_link"
typedef struct {
char *secret;
uint8_t strict;
} secure_link_info;
TSRemapStatus
TSRemapDoRemap(void *ih, TSHttpTxn rh, TSRemapRequestInfo *rri)
{
int i, len;
time_t t, e;
EVP_MD_CTX *ctx;
struct sockaddr_in *in;
const char *qh, *ph, *ip;
unsigned char md[MD5_DIGEST_LENGTH];
secure_link_info *sli = (secure_link_info *)ih;
char *token = NULL, *tokenptr = NULL, *expire = NULL, *expireptr = NULL, *path = NULL;
char *s, *ptr, *saveptr = NULL, *val, hash[32] = "";
in = (struct sockaddr_in *)TSHttpTxnClientAddrGet(rh);
ip = inet_ntoa(in->sin_addr);
s = TSUrlStringGet(rri->requestBufp, rri->requestUrl, &len);
TSDebug(PLUGIN_NAME, "request [%.*s] from [%s]", len, s, ip);
TSfree(s);
qh = TSUrlHttpQueryGet(rri->requestBufp, rri->requestUrl, &len);
if (qh && len > 0) {
s = TSstrndup(qh, len);
if ((ptr = strtok_r(s, "&", &saveptr)) != NULL) {
do {
if ((val = strchr(ptr, '=')) != NULL) {
*val++ = '\0';
if (strcmp(ptr, "st") == 0) {
tokenptr = val;
} else if (strcmp(ptr, "ex") == 0) {
expireptr = val;
}
} else {
TSError("[%s] Invalid parameter [%s]", PLUGIN_NAME, ptr);
break;
}
} while ((ptr = strtok_r(NULL, "&", &saveptr)) != NULL);
token = (NULL == tokenptr ? NULL : TSstrdup(tokenptr));
expire = (NULL == expireptr ? NULL : TSstrdup(expireptr));
} else {
TSError("[%s] strtok didn't find a & in the query string", PLUGIN_NAME);
/* this is just example, so set fake params to prevent plugin crash */
token = TSstrdup("d41d8cd98f00b204e9800998ecf8427e");
expire = TSstrdup("00000000");
}
TSfree(s);
} else {
TSError("[%s] TSUrlHttpQueryGet returns empty value", PLUGIN_NAME);
}
ph = TSUrlPathGet(rri->requestBufp, rri->requestUrl, &len);
if (ph && len > 0) {
s = TSstrndup(ph, len);
if ((ptr = strrchr(s, '/')) != NULL) {
*++ptr = '\0';
}
path = TSstrdup(s);
TSfree(s);
} else {
TSError("[%s] TSUrlPathGet returns empty value", PLUGIN_NAME);
/* this is just example, so set fake params to prevent plugin crash */
path = TSstrdup("example/");
}
#ifdef HAVE_EVP_MD_CTX_NEW
ctx = EVP_MD_CTX_new();
#else
ctx = EVP_MD_CTX_create();
#endif
EVP_DigestInit_ex(ctx, EVP_md5(), NULL);
EVP_DigestUpdate(ctx, sli->secret, strlen(sli->secret));
EVP_DigestUpdate(ctx, ip, strlen(ip));
if (path) {
EVP_DigestUpdate(ctx, path, strlen(path));
}
if (expire) {
EVP_DigestUpdate(ctx, expire, strlen(expire));
}
EVP_DigestFinal_ex(ctx, md, NULL);
#ifdef HAVE_EVP_MD_CTX_FREE
EVP_MD_CTX_free(ctx);
#else
EVP_MD_CTX_destroy(ctx);
#endif
for (i = 0; i < MD5_DIGEST_LENGTH; i++) {
sprintf(&hash[i * 2], "%02x", md[i]);
}
time(&t);
e = (NULL == expire ? 0 : strtol(expire, NULL, 16));
i = TSREMAP_DID_REMAP;
if (e < t || (NULL == token || 0 != strcmp(hash, token))) {
if (e < t) {
TSDebug(PLUGIN_NAME, "link expired: [%lu] vs [%lu]", t, e);
} else {
TSDebug(PLUGIN_NAME, "tokens mismatch: [%s] vs [%s]", hash, token);
}
if (sli->strict) {
TSDebug(PLUGIN_NAME, "request is DENY");
TSHttpTxnStatusSet(rh, TS_HTTP_STATUS_FORBIDDEN);
i = TSREMAP_NO_REMAP;
} else {
TSDebug(PLUGIN_NAME, "request is PASS");
}
}
if (i == TSREMAP_DID_REMAP) {
if (TSUrlHttpQuerySet(rri->requestBufp, rri->requestUrl, "", -1) == TS_SUCCESS) {
s = TSUrlStringGet(rri->requestBufp, rri->requestUrl, &len);
TSDebug(PLUGIN_NAME, "new request string is [%.*s]", len, s);
TSfree(s);
} else {
i = TSREMAP_NO_REMAP;
}
}
TSfree(expire);
TSfree(token);
TSfree(path);
return i;
}
TSReturnCode
TSRemapNewInstance(int argc, char **argv, void **ih, char *errbuf, int errbuf_size)
{
int i;
secure_link_info *sli;
// squash unused variable warnings ...
(void)errbuf;
(void)errbuf_size;
sli = (secure_link_info *)TSmalloc(sizeof(secure_link_info));
sli->secret = NULL;
sli->strict = 0;
for (i = 2; i < argc; i++) {
char *ptr;
if ((ptr = strchr(argv[i], ':')) != NULL) {
*ptr++ = '\0';
if (strcmp(argv[i], "secret") == 0) {
if (sli->secret != NULL) {
TSfree(sli->secret);
}
sli->secret = TSstrdup(ptr);
} else if (strcmp(argv[i], "policy") == 0) {
sli->strict = !strcasecmp(ptr, "strict");
} else {
TSDebug(PLUGIN_NAME, "Unknown parameter [%s]", argv[i]);
}
} else {
TSError("[%s] Invalid parameter [%s]", PLUGIN_NAME, argv[i]);
}
}
if (sli->secret == NULL) {
sli->secret = TSstrdup("");
}
*ih = (void *)sli;
return TS_SUCCESS;
}
void
TSRemapDeleteInstance(void *ih)
{
secure_link_info *sli = (secure_link_info *)ih;
TSfree(sli->secret);
TSfree(sli);
}
TSReturnCode
TSRemapInit(TSRemapInterface *api_info, char *errbuf, int errbuf_size)
{
// squash unused variable warnings ...
(void)api_info;
(void)errbuf;
(void)errbuf_size;
return TS_SUCCESS;
}
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