Added a helper function (SetIpInfoInCmsg) for WritePacket which fills in

net/tools/quic/quic_socket_utils.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/tools/quic/quic_socket_utils.h"
 
 #include <errno.h>
 #include <netinet/in.h>
 #include <string.h>
 #include <sys/socket.h>
@@ skipping 136 matching lines @@
         sizeof(struct sockaddr_in)));
   } else if (raw_address.ss_family == AF_INET6) {
     CHECK(peer_address->FromSockAddr(
         reinterpret_cast<const sockaddr*>(&raw_address),
         sizeof(struct sockaddr_in6)));
   }
 
   return bytes_read;
 }
 
+void QuicSocketUtils::SetIpInfoInCmsg(const IPAddressNumber& self_address,
+                                      cmsghdr* cmsg) {
+  if (GetAddressFamily(self_address) == ADDRESS_FAMILY_IPV4) {
+    cmsg->cmsg_len = CMSG_LEN(sizeof(in_pktinfo));
+    cmsg->cmsg_level = IPPROTO_IP;
+    cmsg->cmsg_type = IP_PKTINFO;
+    in_pktinfo* pktinfo = reinterpret_cast<in_pktinfo*>(CMSG_DATA(cmsg));
+    memset(pktinfo, 0, sizeof(in_pktinfo));
+    pktinfo->ipi_ifindex = 0;
+    memcpy(&pktinfo->ipi_spec_dst, &self_address[0], self_address.size());
+  } else {
+    cmsg->cmsg_len = CMSG_LEN(sizeof(in6_pktinfo));
+    cmsg->cmsg_level = IPPROTO_IPV6;
+    cmsg->cmsg_type = IPV6_PKTINFO;
+    in6_pktinfo* pktinfo = reinterpret_cast<in6_pktinfo*>(CMSG_DATA(cmsg));
+    memset(pktinfo, 0, sizeof(in6_pktinfo));
+    memcpy(&pktinfo->ipi6_addr, &self_address[0], self_address.size());
+  }
+}
+
 // static
 WriteResult QuicSocketUtils::WritePacket(int fd,
                                          const char* buffer,
                                          size_t buf_len,
                                          const IPAddressNumber& self_address,
                                          const IPEndPoint& peer_address) {
   sockaddr_storage raw_address;
   socklen_t address_len = sizeof(raw_address);
   CHECK(peer_address.ToSockAddr(
       reinterpret_cast<struct sockaddr*>(&raw_address),
       &address_len));
   iovec iov = {const_cast<char*>(buffer), buf_len};
 
   msghdr hdr;
   hdr.msg_name = &raw_address;
   hdr.msg_namelen = address_len;
   hdr.msg_iov = &iov;
   hdr.msg_iovlen = 1;
   hdr.msg_flags = 0;
 
   const int kSpaceForIpv4 = CMSG_SPACE(sizeof(in_pktinfo));
   const int kSpaceForIpv6 = CMSG_SPACE(sizeof(in6_pktinfo));
   // kSpaceForIp should be big enough to hold both IPv4 and IPv6 packet info.
   const int kSpaceForIp =
       (kSpaceForIpv4 < kSpaceForIpv6) ? kSpaceForIpv6 : kSpaceForIpv4;
   char cbuf[kSpaceForIp];
   if (self_address.empty()) {
     hdr.msg_control = 0;
     hdr.msg_controllen = 0;
-  } else if (GetAddressFamily(self_address) == ADDRESS_FAMILY_IPV4) {
-    hdr.msg_control = cbuf;
-    hdr.msg_controllen = kSpaceForIp;
-    cmsghdr* cmsg = CMSG_FIRSTHDR(&hdr);
-
-    cmsg->cmsg_len = CMSG_LEN(sizeof(in_pktinfo));
-    cmsg->cmsg_level = IPPROTO_IP;
-    cmsg->cmsg_type = IP_PKTINFO;
-    in_pktinfo* pktinfo = reinterpret_cast<in_pktinfo*>(CMSG_DATA(cmsg));
-    memset(pktinfo, 0, sizeof(in_pktinfo));
-    pktinfo->ipi_ifindex = 0;
-    memcpy(&pktinfo->ipi_spec_dst, &self_address[0], self_address.size());
-    hdr.msg_controllen = cmsg->cmsg_len;
   } else {
     hdr.msg_control = cbuf;
     hdr.msg_controllen = kSpaceForIp;
-    cmsghdr* cmsg = CMSG_FIRSTHDR(&hdr);
-
-    cmsg->cmsg_len = CMSG_LEN(sizeof(in6_pktinfo));
-    cmsg->cmsg_level = IPPROTO_IPV6;
-    cmsg->cmsg_type = IPV6_PKTINFO;
-    in6_pktinfo* pktinfo = reinterpret_cast<in6_pktinfo*>(CMSG_DATA(cmsg));
-    memset(pktinfo, 0, sizeof(in6_pktinfo));
-    memcpy(&pktinfo->ipi6_addr, &self_address[0], self_address.size());
+    cmsghdr *cmsg = CMSG_FIRSTHDR(&hdr);
+    SetIpInfoInCmsg(self_address, cmsg);
     hdr.msg_controllen = cmsg->cmsg_len;
   }
 
   int rc = sendmsg(fd, &hdr, 0);
   if (rc >= 0) {
     return WriteResult(WRITE_STATUS_OK, rc);
   }
   return WriteResult((errno == EAGAIN || errno == EWOULDBLOCK) ?
       WRITE_STATUS_BLOCKED : WRITE_STATUS_ERROR, errno);
 }
 
 }  // namespace tools
 }  // namespace net