Replace QuicSocketUtils::kSpaceForCmsg by a correctly calculated quic::kCmsgSpaceForReadPacket.

Merge internal change: 197832805

R=rch@chromium.org

Change-Id: I2f583a74507647737b330921b25488dc0053e957
Reviewed-on: https://chromium-review.googlesource.com/1070804Reviewed-by: Ryan Hamilton <rch@chromium.org>
Commit-Queue: Bin Wu <wub@chromium.org>
Cr-Commit-Position: refs/heads/master@{#562564}

net/third_party/quic/core/quic_packet_reader.cc

@@ -48,7 +48,7 @@ void QuicPacketReader::Initialize() {
     hdr->msg_iovlen = 1;
 
     hdr->msg_control = packets_[i].cbuf;
-    hdr->msg_controllen = QuicSocketUtils::kSpaceForCmsg;
+    hdr->msg_controllen = kCmsgSpaceForReadPacket;
   }
 #endif
 }
@@ -83,7 +83,8 @@ bool QuicPacketReader::ReadAndDispatchManyPackets(
     msghdr* hdr = &mmsg_hdr_[i].msg_hdr;
     hdr->msg_namelen = sizeof(sockaddr_storage);
     DCHECK_EQ(1, hdr->msg_iovlen);
-    hdr->msg_controllen = QuicSocketUtils::kSpaceForCmsg;
+    hdr->msg_controllen = kCmsgSpaceForReadPacket;
+    hdr->msg_flags = 0;
   }
 
   int packets_read =
@@ -99,10 +100,10 @@ bool QuicPacketReader::ReadAndDispatchManyPackets(
       continue;
     }
 
-    if (mmsg_hdr_[i].msg_hdr.msg_controllen >= QuicSocketUtils::kSpaceForCmsg) {
+    if (mmsg_hdr_[i].msg_hdr.msg_flags & MSG_CTRUNC) {
       QUIC_BUG << "Incorrectly set control length: "
                << mmsg_hdr_[i].msg_hdr.msg_controllen << ", expected "
-               << QuicSocketUtils::kSpaceForCmsg;
+               << kCmsgSpaceForReadPacket;
       continue;
     }
 

net/third_party/quic/core/quic_packet_reader.h

@@ -79,7 +79,7 @@ class QuicPacketReader {
     // call on the packets.
     struct sockaddr_storage raw_address;
     // cbuf is used for ancillary data from the kernel on recvmmsg.
-    char cbuf[QuicSocketUtils::kSpaceForCmsg];
+    char cbuf[kCmsgSpaceForReadPacket];
     // buf is used for the data read from the kernel on recvmmsg.
     char buf[kMaxPacketSize];
   };

net/third_party/quic/platform/impl/quic_socket_utils.cc

@@ -139,8 +139,7 @@ int QuicSocketUtils::ReadPacket(int fd,
                                 QuicWallTime* walltimestamp,
                                 QuicSocketAddress* peer_address) {
   DCHECK(peer_address != nullptr);
-  char cbuf[kSpaceForCmsg];
-  memset(cbuf, 0, arraysize(cbuf));
+  char cbuf[kCmsgSpaceForReadPacket];
 
   iovec iov = {buffer, buf_len};
   struct sockaddr_storage raw_address;
@@ -168,7 +167,7 @@ int QuicSocketUtils::ReadPacket(int fd,
     return -1;
   }
 
-  if (hdr.msg_controllen >= arraysize(cbuf)) {
+  if (hdr.msg_flags & MSG_CTRUNC) {
     QUIC_BUG << "Incorrectly set control length: " << hdr.msg_controllen
              << ", expected " << arraysize(cbuf);
     return -1;

net/third_party/quic/platform/impl/quic_socket_utils.h

@@ -36,18 +36,28 @@ struct LinuxTimestamping {
   struct timespec hwtimeraw;
 };
 
+const int kCmsgSpaceForIpv4 = CMSG_SPACE(sizeof(in_pktinfo));
+const int kCmsgSpaceForIpv6 = CMSG_SPACE(sizeof(in6_pktinfo));
+// kCmsgSpaceForIp should be big enough to hold both IPv4 and IPv6 packet info.
+const int kCmsgSpaceForIp = (kCmsgSpaceForIpv4 < kCmsgSpaceForIpv6)
+                                ? kCmsgSpaceForIpv6
+                                : kCmsgSpaceForIpv4;
+
+const int kCmsgSpaceForSegmentSize = CMSG_SPACE(sizeof(uint16_t));
+
+const int kCmsgSpaceForRecvQueueOverflow = CMSG_SPACE(sizeof(int));
+const int kCmsgSpaceForLinuxTimestamping =
+    CMSG_SPACE(sizeof(LinuxTimestamping));
+const int kCmsgSpaceForTTL = CMSG_SPACE(sizeof(int));
+
+// The minimum cmsg buffer size when receiving a packet. It is possible for a
+// received packet to contain both IPv4 and IPv6 addresses.
+const int kCmsgSpaceForReadPacket =
+    kCmsgSpaceForRecvQueueOverflow + kCmsgSpaceForIpv4 + kCmsgSpaceForIpv6 +
+    kCmsgSpaceForLinuxTimestamping + kCmsgSpaceForTTL;
+
 class QuicSocketUtils {
  public:
-  // The first integer is for overflow. The in6_pktinfo is the larger of the
-  // address structures present. LinuxTimestamping is present for socket
-  // timestamping.  The subsequent int is for ttl.
-  // The final int is a sentinel so the msg_controllen feedback
-  // can be used to detect larger control messages than there is space for.
-  static const int kSpaceForCmsg =
-      CMSG_SPACE(CMSG_LEN(sizeof(int)) + CMSG_LEN(sizeof(in6_pktinfo)) +
-                 CMSG_LEN(sizeof(LinuxTimestamping)) + CMSG_LEN(sizeof(int)) +
-                 CMSG_LEN(sizeof(int)));
-
   // Fills in |address| if |hdr| contains IP_PKTINFO or IPV6_PKTINFO. Fills in
   // |timestamp| if |hdr| contains |SO_TIMESTAMPING|. |address| and |timestamp|
   // must not be null.