muduo_base代码剖析之Socket API封装

一、Endian.h

封装了字节序转换函数(全局函数，位于muduo::net::sockets命名空间中)

namespace muduo
{
namespace net
{
namespace sockets
{
主机字节序 ---> 网络字节序
inline uint64_t hostToNetwork64(uint64_t host64)
{
  return htobe64(host64); //主机字节序转换成大端/网络字节序
}
inline uint32_t hostToNetwork32(uint32_t host32)
{
  return htobe32(host32);
}
inline uint16_t hostToNetwork16(uint16_t host16)
{
  return htobe16(host16);
}

网络字节序 ---> 主机字节序
inline uint64_t networkToHost64(uint64_t net64)
{
  return be64toh(net64);
}
inline uint32_t networkToHost32(uint32_t net32)
{
  return be32toh(net32);
}
inline uint16_t networkToHost16(uint16_t net16)
{
  return be16toh(net16);
}
}  // namespace sockets
}  // namespace net
}  // namespace muduo

二、SocketsOps

封装了socket相关系统调用(全局函数，位于muduo::net::sockets命名空间中)

namespace muduo
{
namespace net
{
namespace sockets
{
int createNonblockingOrDie(sa_family_t family);

int  connect(int sockfd, const struct sockaddr* addr);
void bindOrDie(int sockfd, const struct sockaddr* addr);
void listenOrDie(int sockfd);
int  accept(int sockfd, struct sockaddr_in6* addr); //accept，新连接的套接字connfd设为非阻塞
ssize_t read(int sockfd, void *buf, size_t count);
ssize_t readv(int sockfd, const struct iovec *iov, int iovcnt);
ssize_t write(int sockfd, const void *buf, size_t count);
void close(int sockfd);
void shutdownWrite(int sockfd);

void toIpPort(char* buf, size_t size,
              const struct sockaddr* addr);
void toIp(char* buf, size_t size,
          const struct sockaddr* addr);

void fromIpPort(const char* ip, uint16_t port,
                struct sockaddr_in* addr);
void fromIpPort(const char* ip, uint16_t port,
                struct sockaddr_in6* addr);

int getSocketError(int sockfd);

const struct sockaddr* sockaddr_cast(const struct sockaddr_in* addr);
const struct sockaddr* sockaddr_cast(const struct sockaddr_in6* addr);
struct sockaddr* sockaddr_cast(struct sockaddr_in6* addr);
const struct sockaddr_in* sockaddr_in_cast(const struct sockaddr* addr);
const struct sockaddr_in6* sockaddr_in6_cast(const struct sockaddr* addr);

struct sockaddr_in6 getLocalAddr(int sockfd);
struct sockaddr_in6 getPeerAddr(int sockfd);
bool isSelfConnect(int sockfd);

}  // namespace sockets
}  // namespace net
}  // namespace muduo

//设置sockfd属性为O_NONBLOCK|FD_CLOEXEC
void setNonBlockAndCloseOnExec(int sockfd) 
{
  // non-block
  int flags = ::fcntl(sockfd, F_GETFL, 0);
  flags |= O_NONBLOCK;
  int ret = ::fcntl(sockfd, F_SETFL, flags);
  // FIXME check

  // close-on-exec
  flags = ::fcntl(sockfd, F_GETFD, 0);
  flags |= FD_CLOEXEC;
  ret = ::fcntl(sockfd, F_SETFD, flags);
  // FIXME check

  (void)ret;
}
#endif

}  
//类型转换函数
const struct sockaddr* sockets::sockaddr_cast(const struct sockaddr_in6* addr)
{
  return static_cast<const struct sockaddr*>(implicit_cast<const void*>(addr));
}
struct sockaddr* sockets::sockaddr_cast(struct sockaddr_in6* addr)
{
  return static_cast<struct sockaddr*>(implicit_cast<void*>(addr));
}
const struct sockaddr* sockets::sockaddr_cast(const struct sockaddr_in* addr)
{
  return static_cast<const struct sockaddr*>(implicit_cast<const void*>(addr));
}
const struct sockaddr_in* sockets::sockaddr_in_cast(const struct sockaddr* addr)
{
  return static_cast<const struct sockaddr_in*>(implicit_cast<const void*>(addr));
}
const struct sockaddr_in6* sockets::sockaddr_in6_cast(const struct sockaddr* addr)
{
  return static_cast<const struct sockaddr_in6*>(implicit_cast<const void*>(addr));
}
//创建非阻塞套接字
int sockets::createNonblockingOrDie(sa_family_t family)
{
#if VALGRIND
  int sockfd = ::socket(family, SOCK_STREAM, IPPROTO_TCP);
  if (sockfd < 0)
  {
    LOG_SYSFATAL << "sockets::createNonblockingOrDie";
  }

  setNonBlockAndCloseOnExec(sockfd);
#else
  int sockfd = ::socket(family, SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC, IPPROTO_TCP);
  if (sockfd < 0)
  {
    LOG_SYSFATAL << "sockets::createNonblockingOrDie";
  }
#endif
  return sockfd;
}
//bind
void sockets::bindOrDie(int sockfd, const struct sockaddr* addr)
{
  int ret = ::bind(sockfd, addr, static_cast<socklen_t>(sizeof(struct sockaddr_in6)));
  if (ret < 0)
  {
    LOG_SYSFATAL << "sockets::bindOrDie";
  }
}
//listen
void sockets::listenOrDie(int sockfd)
{
  int ret = ::listen(sockfd, SOMAXCONN);
  if (ret < 0)
  {
    LOG_SYSFATAL << "sockets::listenOrDie";
  }
}
//accept，新连接的套接字connfd设为非阻塞
int sockets::accept(int sockfd, struct sockaddr_in6* addr)
{
  socklen_t addrlen = static_cast<socklen_t>(sizeof *addr);
#if VALGRIND || defined (NO_ACCEPT4)
  int connfd = ::accept(sockfd, sockaddr_cast(addr), &addrlen);
  setNonBlockAndCloseOnExec(connfd);
#else
  int connfd = ::accept4(sockfd, sockaddr_cast(addr),
                         &addrlen, SOCK_NONBLOCK | SOCK_CLOEXEC);
#endif
  if (connfd < 0)
  {
    int savedErrno = errno;
    LOG_SYSERR << "Socket::accept";
    switch (savedErrno)
    {
      case EAGAIN:
      case ECONNABORTED:
      case EINTR:
      case EPROTO: // ???
      case EPERM:
      case EMFILE: // per-process lmit of open file desctiptor ???
        // expected errors
        errno = savedErrno;
        break;
      case EBADF:
      case EFAULT:
      case EINVAL:
      case ENFILE:
      case ENOBUFS:
      case ENOMEM:
      case ENOTSOCK:
      case EOPNOTSUPP:
        // unexpected errors
        LOG_FATAL << "unexpected error of ::accept " << savedErrno;
        break;
      default:
        LOG_FATAL << "unknown error of ::accept " << savedErrno;
        break;
    }
  }
  return connfd;
}
//connect
int sockets::connect(int sockfd, const struct sockaddr* addr)
{
  return ::connect(sockfd, addr, static_cast<socklen_t>(sizeof(struct sockaddr_in6)));
}
//read
ssize_t sockets::read(int sockfd, void *buf, size_t count)
{
  return ::read(sockfd, buf, count);
}
//readv
ssize_t sockets::readv(int sockfd, const struct iovec *iov, int iovcnt)
{
  return ::readv(sockfd, iov, iovcnt);
}
//write
ssize_t sockets::write(int sockfd, const void *buf, size_t count)
{
  return ::write(sockfd, buf, count);
}
//close
void sockets::close(int sockfd)
{
  if (::close(sockfd) < 0)
  {
    LOG_SYSERR << "sockets::close";
  }
}
//shutdownWrite
void sockets::shutdownWrite(int sockfd)
{
  if (::shutdown(sockfd, SHUT_WR) < 0)
  {
    LOG_SYSERR << "sockets::shutdownWrite";
  }
}

void sockets::toIpPort(char* buf, size_t size,
                       const struct sockaddr* addr)
{
  toIp(buf,size, addr);
  size_t end = ::strlen(buf);
  const struct sockaddr_in* addr4 = sockaddr_in_cast(addr);
  uint16_t port = sockets::networkToHost16(addr4->sin_port);
  assert(size > end);
  snprintf(buf+end, size-end, ":%u", port);
}
//addr ---> buf
void sockets::toIp(char* buf, size_t size,
                   const struct sockaddr* addr)
{
  if (addr->sa_family == AF_INET)
  {
    assert(size >= INET_ADDRSTRLEN);
    const struct sockaddr_in* addr4 = sockaddr_in_cast(addr);
    ::inet_ntop(AF_INET, &addr4->sin_addr, buf, static_cast<socklen_t>(size));
  }
  else if (addr->sa_family == AF_INET6)
  {
    assert(size >= INET6_ADDRSTRLEN);
    const struct sockaddr_in6* addr6 = sockaddr_in6_cast(addr);
    ::inet_ntop(AF_INET6, &addr6->sin6_addr, buf, static_cast<socklen_t>(size));
  }
}

void sockets::fromIpPort(const char* ip, uint16_t port,
                         struct sockaddr_in* addr)
{
  addr->sin_family = AF_INET;
  addr->sin_port = hostToNetwork16(port);
  if (::inet_pton(AF_INET, ip, &addr->sin_addr) <= 0)
  {
    LOG_SYSERR << "sockets::fromIpPort";
  }
}

void sockets::fromIpPort(const char* ip, uint16_t port,
                         struct sockaddr_in6* addr)
{
  addr->sin6_family = AF_INET6;
  addr->sin6_port = hostToNetwork16(port);
  if (::inet_pton(AF_INET6, ip, &addr->sin6_addr) <= 0)
  {
    LOG_SYSERR << "sockets::fromIpPort";
  }
}

int sockets::getSocketError(int sockfd)
{
  int optval;
  socklen_t optlen = static_cast<socklen_t>(sizeof optval);

  if (::getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) < 0)
  {
    return errno;
  }
  else
  {
    return optval;
  }
}

struct sockaddr_in6 sockets::getLocalAddr(int sockfd)
{
  struct sockaddr_in6 localaddr;
  memZero(&localaddr, sizeof localaddr);
  socklen_t addrlen = static_cast<socklen_t>(sizeof localaddr);
  if (::getsockname(sockfd, sockaddr_cast(&localaddr), &addrlen) < 0)
  {
    LOG_SYSERR << "sockets::getLocalAddr";
  }
  return localaddr;
}

struct sockaddr_in6 sockets::getPeerAddr(int sockfd)
{
  struct sockaddr_in6 peeraddr;
  memZero(&peeraddr, sizeof peeraddr);
  socklen_t addrlen = static_cast<socklen_t>(sizeof peeraddr);
  if (::getpeername(sockfd, sockaddr_cast(&peeraddr), &addrlen) < 0)
  {
    LOG_SYSERR << "sockets::getPeerAddr";
  }
  return peeraddr;
}

bool sockets::isSelfConnect(int sockfd)
{
  struct sockaddr_in6 localaddr = getLocalAddr(sockfd);
  struct sockaddr_in6 peeraddr = getPeerAddr(sockfd);
  if (localaddr.sin6_family == AF_INET)
  {
    const struct sockaddr_in* laddr4 = reinterpret_cast<struct sockaddr_in*>(&localaddr);
    const struct sockaddr_in* raddr4 = reinterpret_cast<struct sockaddr_in*>(&peeraddr);
    return laddr4->sin_port == raddr4->sin_port
        && laddr4->sin_addr.s_addr == raddr4->sin_addr.s_addr;
  }
  else if (localaddr.sin6_family == AF_INET6)
  {
    return localaddr.sin6_port == peeraddr.sin6_port
        && memcmp(&localaddr.sin6_addr, &peeraddr.sin6_addr, sizeof localaddr.sin6_addr) == 0;
  }
  else
  {
    return false;
  }
}

三、InetAddress 网际地址sockaddr_in的封装

class InetAddress : public muduo::copyable
{
private:
  union  //唯一的成员变量
  {
    struct sockaddr_in addr_;
    struct sockaddr_in6 addr6_;
  };
public:
  //仅仅指定port，不指定ip，则ip为ANADDR_ANY，即0.0.0.0
  explicit InetAddress(uint16_t port = 0, bool loopbackOnly = false, bool ipv6 = false);
  /// ip should be "1.2.3.4"
  InetAddress(StringArg ip, uint16_t port, bool ipv6 = false);
  explicit InetAddress(const struct sockaddr_in& addr)
    : addr_(addr)
  { }
  explicit InetAddress(const struct sockaddr_in6& addr)
    : addr6_(addr)
  { }

  sa_family_t family() const { return addr_.sin_family; }
  
  string toIp() const;
  string toIpPort() const;
  uint16_t toPort() const;

  const struct sockaddr* getSockAddr() const { return sockets::sockaddr_cast(&addr6_); }
  void setSockAddrInet6(const struct sockaddr_in6& addr6) { addr6_ = addr6; }

  //返回网络字节序的uint32_t的ip
  uint32_t ipNetEndian() const;
  //返回网络字节序的uint32_t的port
  uint16_t portNetEndian() const { return addr_.sin_port; }

  static bool resolve(StringArg hostname, InetAddress* result);
};

//构造函数
InetAddress::InetAddress(uint16_t port, bool loopbackOnly, bool ipv6)
{
  static_assert(offsetof(InetAddress, addr6_) == 0, "addr6_ offset 0");
  static_assert(offsetof(InetAddress, addr_) == 0, "addr_ offset 0");
  if (ipv6)
  {
    memZero(&addr6_, sizeof addr6_);
    addr6_.sin6_family = AF_INET6;
    in6_addr ip = loopbackOnly ? in6addr_loopback : in6addr_any;
    addr6_.sin6_addr = ip;
    addr6_.sin6_port = sockets::hostToNetwork16(port);
  }
  else
  {
    memZero(&addr_, sizeof addr_);
    addr_.sin_family = AF_INET;
    in_addr_t ip = loopbackOnly ? kInaddrLoopback : kInaddrAny;
    addr_.sin_addr.s_addr = sockets::hostToNetwork32(ip);
    addr_.sin_port = sockets::hostToNetwork16(port);
  }
}
//构造函数
InetAddress::InetAddress(StringArg ip, uint16_t port, bool ipv6)
{
  if (ipv6)
  {
    memZero(&addr6_, sizeof addr6_);
    sockets::fromIpPort(ip.c_str(), port, &addr6_);
  }
  else
  {
    memZero(&addr_, sizeof addr_);
    sockets::fromIpPort(ip.c_str(), port, &addr_);
  }
}

string InetAddress::toIpPort() const
{
  char buf[64] = "";
  sockets::toIpPort(buf, sizeof buf, getSockAddr());
  return buf;
}
string InetAddress::toIp() const
{
  char buf[64] = "";
  sockets::toIp(buf, sizeof buf, getSockAddr());
  return buf;
}
uint16_t InetAddress::toPort() const
{
  return sockets::networkToHost16(portNetEndian());
}

//返回网络字节序的uint32_t的ip
uint32_t InetAddress::ipNetEndian() const
{
  assert(family() == AF_INET);
  return addr_.sin_addr.s_addr;
}

static __thread char t_resolveBuffer[64 * 1024];

bool InetAddress::resolve(StringArg hostname, InetAddress* out)
{
  assert(out != NULL);
  struct hostent hent;
  struct hostent* he = NULL;
  int herrno = 0;
  memZero(&hent, sizeof(hent));

  int ret = gethostbyname_r(hostname.c_str(), &hent, t_resolveBuffer, sizeof t_resolveBuffer, &he, &herrno);
  if (ret == 0 && he != NULL)
  {
    assert(he->h_addrtype == AF_INET && he->h_length == sizeof(uint32_t));
    out->addr_.sin_addr = *reinterpret_cast<struct in_addr*>(he->h_addr);
    return true;
  }
  else
  {
    if (ret)
    {
      LOG_SYSERR << "InetAddress::resolve";
    }
    return false;
  }
}

四、Socket类

用RAII方法封装socket file descriptor

struct tcp_info;

class InetAddress;
class Socket : noncopyable
{
private:
  const int sockfd_;
public:
  explicit Socket(int sockfd)
    : sockfd_(sockfd)
  { }

  ~Socket();

  int fd() const { return sockfd_; }

  bool getTcpInfo(struct tcp_info*) const;
  bool getTcpInfoString(char* buf, int len) const;

  void bindAddress(const InetAddress& localaddr);
  void listen();

  int accept(InetAddress* peeraddr);

  void shutdownWrite();

  void setTcpNoDelay(bool on);
  void setReuseAddr(bool on);
  void setReusePort(bool on);
  void setKeepAlive(bool on);
};

Socket::~Socket()
{
  sockets::close(sockfd_);
}

bool Socket::getTcpInfo(struct tcp_info* tcpi) const
{
  socklen_t len = sizeof(*tcpi);
  memZero(tcpi, len);
  return ::getsockopt(sockfd_, SOL_TCP, TCP_INFO, tcpi, &len) == 0;
}

bool Socket::getTcpInfoString(char* buf, int len) const
{
  struct tcp_info tcpi;
  bool ok = getTcpInfo(&tcpi);
  if (ok)
  {
    snprintf(buf, len, "unrecovered=%u "
             "rto=%u ato=%u snd_mss=%u rcv_mss=%u "
             "lost=%u retrans=%u rtt=%u rttvar=%u "
             "sshthresh=%u cwnd=%u total_retrans=%u",
             tcpi.tcpi_retransmits,  // Number of unrecovered [RTO] timeouts
             tcpi.tcpi_rto,          // Retransmit timeout in usec
             tcpi.tcpi_ato,          // Predicted tick of soft clock in usec
             tcpi.tcpi_snd_mss,
             tcpi.tcpi_rcv_mss,
             tcpi.tcpi_lost,         // Lost packets
             tcpi.tcpi_retrans,      // Retransmitted packets out
             tcpi.tcpi_rtt,          // Smoothed round trip time in usec
             tcpi.tcpi_rttvar,       // Medium deviation
             tcpi.tcpi_snd_ssthresh,
             tcpi.tcpi_snd_cwnd,
             tcpi.tcpi_total_retrans);  // Total retransmits for entire connection
  }
  return ok;
}

void Socket::bindAddress(const InetAddress& addr)
{
  sockets::bindOrDie(sockfd_, addr.getSockAddr());
}

void Socket::listen()
{
  sockets::listenOrDie(sockfd_);
}

int Socket::accept(InetAddress* peeraddr)
{
  struct sockaddr_in6 addr;
  memZero(&addr, sizeof addr);
  int connfd = sockets::accept(sockfd_, &addr);
  if (connfd >= 0)
  {
    peeraddr->setSockAddrInet6(addr);
  }
  return connfd;
}

void Socket::shutdownWrite()
{
  sockets::shutdownWrite(sockfd_);
}

void Socket::setTcpNoDelay(bool on)
{
  int optval = on ? 1 : 0;
  ::setsockopt(sockfd_, IPPROTO_TCP, TCP_NODELAY,
               &optval, static_cast<socklen_t>(sizeof optval));
}

void Socket::setReuseAddr(bool on)
{
  int optval = on ? 1 : 0;
  ::setsockopt(sockfd_, SOL_SOCKET, SO_REUSEADDR,
               &optval, static_cast<socklen_t>(sizeof optval));
}

void Socket::setReusePort(bool on)
{
#ifdef SO_REUSEPORT
  int optval = on ? 1 : 0;
  int ret = ::setsockopt(sockfd_, SOL_SOCKET, SO_REUSEPORT,
                         &optval, static_cast<socklen_t>(sizeof optval));
  if (ret < 0 && on)
  {
    LOG_SYSERR << "SO_REUSEPORT failed.";
  }
#else
  if (on)
  {
    LOG_ERROR << "SO_REUSEPORT is not supported.";
  }
#endif
}

void Socket::setKeepAlive(bool on)
{
  int optval = on ? 1 : 0;
  ::setsockopt(sockfd_, SOL_SOCKET, SO_KEEPALIVE,
               &optval, static_cast<socklen_t>(sizeof optval));
  // FIXME CHECK
}