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non blocking dns lookup

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This commit is contained in:
Benjamin Sergeant
2018-12-14 16:28:11 -08:00
parent 8c079787f0
commit cbadecab33
17 changed files with 323 additions and 52 deletions
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44
ixwebsocket/IXSocketConnect.cpp
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@@ -5,6 +5,7 @@
*/
#include "IXSocketConnect.h"
#include "IXDNSLookup.h"
#ifdef _WIN32
# include <basetsd.h>
@@ -47,10 +48,15 @@ namespace
namespace ix
{
//
// This function can be cancelled every 50 ms
// This is important so that we don't block the main UI thread when shutting down a connection which is
// already trying to reconnect, and can be blocked waiting for ::connect to respond.
//
bool SocketConnect::connectToAddress(const struct addrinfo *address,
int& sockfd,
std::string& errMsg,
CancellationRequest isCancellationRequested)
const CancellationRequest& isCancellationRequested)
{
sockfd = -1;
@@ -64,20 +70,17 @@ namespace ix
}
// Set the socket to non blocking mode, so that slow responses cannot
// block us for too long while we are trying to shut-down.
// block us for too long
SocketConnect::configure(fd);
if (::connect(fd, address->ai_addr, address->ai_addrlen) == -1
&& errno != EINPROGRESS)
{
closeSocket(fd);
sockfd = -1;
errMsg = strerror(errno);
return false;
}
// std::cout << "I WAS HERE A" << std::endl;
//
// If during a connection attempt the request remains idle for longer
// than the timeout interval, the request is considered to have timed
@@ -95,7 +98,6 @@ namespace ix
if (isCancellationRequested())
{
closeSocket(fd);
sockfd = -1;
errMsg = "Cancelled";
return false;
}
@@ -115,7 +117,7 @@ namespace ix
if (!FD_ISSET(fd, &wfds)) continue;
// Something was written to the socket
int optval;
int optval = -1;
socklen_t optlen = sizeof(optval);
// getsockopt() puts the errno value for connect into optval so 0
@@ -124,7 +126,6 @@ namespace ix
optval != 0)
{
closeSocket(fd);
sockfd = -1;
errMsg = strerror(optval);
return false;
}
@@ -137,33 +138,22 @@ namespace ix
}
closeSocket(fd);
sockfd = -1;
errMsg = strerror(errno);
errMsg = "connect timed out after 60 seconds";
return false;
}
int SocketConnect::connect(const std::string& hostname,
int port,
std::string& errMsg,
CancellationRequest isCancellationRequested)
const CancellationRequest& isCancellationRequested)
{
//
// First do DNS resolution
//
struct addrinfo hints;
memset(&hints, 0, sizeof(hints));
hints.ai_flags = AI_ADDRCONFIG | AI_NUMERICSERV;
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
std::string sport = std::to_string(port);
struct addrinfo *res = nullptr;
int getaddrinfo_result = getaddrinfo(hostname.c_str(), sport.c_str(),
&hints, &res);
if (getaddrinfo_result)
DNSLookup dnsLookup(hostname, port);
struct addrinfo *res = dnsLookup.resolve(errMsg, isCancellationRequested);
if (res == nullptr)
{
errMsg = gai_strerror(getaddrinfo_result);
return -1;
}
@@ -183,15 +173,18 @@ namespace ix
break;
}
}
freeaddrinfo(res);
return sockfd;
}
void SocketConnect::configure(int sockfd)
{
// 1. disable Nagle's algorithm
int flag = 1;
setsockopt(sockfd, IPPROTO_TCP, TCP_NODELAY, (char*) &flag, sizeof(flag)); // Disable Nagle's algorithm
setsockopt(sockfd, IPPROTO_TCP, TCP_NODELAY, (char*) &flag, sizeof(flag));
// 2. make socket non blocking
#ifdef _WIN32
unsigned long nonblocking = 1;
ioctlsocket(_sockfd, FIONBIO, &nonblocking);
@@ -199,6 +192,7 @@ namespace ix
fcntl(sockfd, F_SETFL, O_NONBLOCK); // make socket non blocking
#endif
// 3. (apple) prevent SIGPIPE from being emitted when the remote end disconnect
#ifdef SO_NOSIGPIPE
int value = 1;
setsockopt(sockfd, SOL_SOCKET, SO_NOSIGPIPE,