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From zw...@apache.org
Subject [trafficserver] branch 9.0.x updated: correct the size of DNS buffers
Date Fri, 30 Aug 2019 21:43:45 GMT
This is an automated email from the ASF dual-hosted git repository.

zwoop pushed a commit to branch 9.0.x
in repository https://gitbox.apache.org/repos/asf/trafficserver.git


The following commit(s) were added to refs/heads/9.0.x by this push:
     new 3c93d86  correct the size of DNS buffers
3c93d86 is described below

commit 3c93d86f48182b4defbe2d1b5dd0d42fa577e244
Author: Zizhong Zhang <zizhang@linkedin.com>
AuthorDate: Tue Aug 20 18:18:56 2019 -0700

    correct the size of DNS buffers
    
    (cherry picked from commit 1b98e7f4c786a0a1ff675e95d23a59ecd6a852c2)
---
 iocore/dns/DNS.cc           | 12 ++++++------
 iocore/dns/I_DNSProcessor.h | 19 ++++++++++---------
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/iocore/dns/DNS.cc b/iocore/dns/DNS.cc
index 7a7df3b..8d91744 100644
--- a/iocore/dns/DNS.cc
+++ b/iocore/dns/DNS.cc
@@ -597,7 +597,7 @@ static inline int
 _ink_res_mkquery(ink_res_state res, char *qname, int qtype, unsigned char *buffer, bool over_tcp
= false)
 {
   int offset = over_tcp ? tcp_data_length_offset : 0;
-  int r      = ink_res_mkquery(res, QUERY, qname, C_IN, qtype, nullptr, 0, nullptr, buffer
+ offset, MAX_DNS_PACKET_LEN);
+  int r      = ink_res_mkquery(res, QUERY, qname, C_IN, qtype, nullptr, 0, nullptr, buffer
+ offset, MAX_DNS_REQUEST_LEN - offset);
   if (over_tcp) {
     NS_PUT16(r, buffer);
   }
@@ -629,7 +629,7 @@ DNSHandler::retry_named(int ndx, ink_hrtime t, bool reopen)
   }
   bool over_tcp = dns_conn_mode == DNS_CONN_MODE::TCP_ONLY;
   int con_fd    = over_tcp ? tcpcon[ndx].fd : udpcon[ndx].fd;
-  unsigned char buffer[MAX_DNS_PACKET_LEN];
+  unsigned char buffer[MAX_DNS_REQUEST_LEN];
   Debug("dns", "trying to resolve '%s' from DNS connection, ndx %d", try_server_names[try_servers],
ndx);
   int r       = _ink_res_mkquery(m_res, try_server_names[try_servers], T_A, buffer, over_tcp);
   try_servers = (try_servers + 1) % countof(try_server_names);
@@ -650,7 +650,7 @@ DNSHandler::try_primary_named(bool reopen)
     open_cons(&ip.sa, true, 0);
   }
   if ((t - last_primary_retry) > DNS_PRIMARY_RETRY_PERIOD) {
-    unsigned char buffer[MAX_DNS_PACKET_LEN];
+    unsigned char buffer[MAX_DNS_REQUEST_LEN];
     bool over_tcp      = dns_conn_mode == DNS_CONN_MODE::TCP_ONLY;
     int con_fd         = over_tcp ? tcpcon[0].fd : udpcon[0].fd;
     last_primary_retry = t;
@@ -824,7 +824,7 @@ DNSHandler::recv_dns(int /* event ATS_UNUSED */, Event * /* e ATS_UNUSED
*/)
             goto Lerror;
           }
           dnsc->tcp_data.total_length = ntohs(dnsc->tcp_data.total_length);
-          if (res != sizeof(dnsc->tcp_data.total_length) || dnsc->tcp_data.total_length
> MAX_DNS_PACKET_LEN) {
+          if (res != sizeof(dnsc->tcp_data.total_length)) {
             goto Lerror;
           }
         }
@@ -852,7 +852,7 @@ DNSHandler::recv_dns(int /* event ATS_UNUSED */, Event * /* e ATS_UNUSED
*/)
         hostent_cache = dnsBufAllocator.alloc();
       }
 
-      res = socketManager.recvfrom(dnsc->fd, hostent_cache->buf, MAX_DNS_PACKET_LEN,
0, &from_ip.sa, &from_length);
+      res = socketManager.recvfrom(dnsc->fd, hostent_cache->buf, MAX_DNS_RESPONSE_LEN,
0, &from_ip.sa, &from_length);
       Debug("dns", "DNSHandler::recv_dns res = [%d]", res);
       if (res == -EAGAIN) {
         break;
@@ -1092,7 +1092,7 @@ static bool
 write_dns_event(DNSHandler *h, DNSEntry *e, bool over_tcp)
 {
   ProxyMutex *mutex = h->mutex.get();
-  unsigned char buffer[MAX_DNS_PACKET_LEN];
+  unsigned char buffer[MAX_DNS_REQUEST_LEN];
   int offset     = over_tcp ? tcp_data_length_offset : 0;
   HEADER *header = reinterpret_cast<HEADER *>(buffer + offset);
   int r          = 0;
diff --git a/iocore/dns/I_DNSProcessor.h b/iocore/dns/I_DNSProcessor.h
index a0ec651..83f4bd2 100644
--- a/iocore/dns/I_DNSProcessor.h
+++ b/iocore/dns/I_DNSProcessor.h
@@ -28,11 +28,12 @@
 const int DOMAIN_SERVICE_PORT        = NAMESERVER_PORT;
 const int DEFAULT_DOMAIN_NAME_SERVER = 0;
 
-const int MAX_DNS_PACKET_LEN = 8192;
-const int DNS_RR_MAX_COUNT   = (MAX_DNS_PACKET_LEN - HFIXEDSZ + RRFIXEDSZ - 1) / RRFIXEDSZ;
-const int DNS_MAX_ALIASES    = DNS_RR_MAX_COUNT;
-const int DNS_MAX_ADDRS      = DNS_RR_MAX_COUNT;
-const int DNS_HOSTBUF_SIZE   = MAX_DNS_PACKET_LEN;
+const int MAX_DNS_REQUEST_LEN  = NS_PACKETSZ;
+const int MAX_DNS_RESPONSE_LEN = 65536;
+const int DNS_RR_MAX_COUNT     = (MAX_DNS_RESPONSE_LEN - HFIXEDSZ + RRFIXEDSZ - 1) / RRFIXEDSZ;
+const int DNS_MAX_ALIASES      = DNS_RR_MAX_COUNT;
+const int DNS_MAX_ADDRS        = DNS_RR_MAX_COUNT;
+const int DNS_HOSTBUF_SIZE     = MAX_DNS_RESPONSE_LEN;
 
 /**
   All buffering required to handle a DNS receipt. For asynchronous DNS,
@@ -41,10 +42,10 @@ const int DNS_HOSTBUF_SIZE   = MAX_DNS_PACKET_LEN;
 
 */
 struct HostEnt : RefCountObj {
-  struct hostent ent           = {.h_name = nullptr, .h_aliases = nullptr, .h_addrtype =
0, .h_length = 0, .h_addr_list = nullptr};
-  uint32_t ttl                 = 0;
-  int packet_size              = 0;
-  char buf[MAX_DNS_PACKET_LEN] = {0};
+  struct hostent ent = {.h_name = nullptr, .h_aliases = nullptr, .h_addrtype = 0, .h_length
= 0, .h_addr_list = nullptr};
+  uint32_t ttl       = 0;
+  int packet_size    = 0;
+  char buf[MAX_DNS_RESPONSE_LEN]         = {0};
   u_char *host_aliases[DNS_MAX_ALIASES]  = {nullptr};
   u_char *h_addr_ptrs[DNS_MAX_ADDRS + 1] = {nullptr};
   u_char hostbuf[DNS_HOSTBUF_SIZE]       = {0};


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