fix IPv6 proxy connectivity

The proxy code path in ConnectionSocket::openConnection() hardcoded
socket(AF_INET, ...) before the proxy address was parsed. When the
proxy address is an IPv6 literal, the later inet_pton(AF_INET6, ...)
fills socketAddress6 and flips ipv6 = true, but the subsequent
openConnectionInternal() then calls connect() with sockaddr_in6 on an
AF_INET fd and fails with EAFNOSUPPORT. Likewise onHostNameResolved()
only tried inet_pton(AF_INET, ...), so proxy hostnames the Android
delegate resolved to an IPv6 address also failed.

Move socket() creation into openConnectionInternal() so it uses the
final ipv6 flag, pre-init socketAddress6.sin6_family/sin6_port in the
proxy branch, and derive ipv6 in onHostNameResolved() by cascading
inet_pton(AF_INET) -> inet_pton(AF_INET6) on the resolved IP.

Ports DrKLO/Telegram PR DrKLO#1959 with light cleanup (hoisted ip.empty()
short-circuit, no parameter shadow). Drop on next rebase once upstream
merges.

Fixes bugs.telegram.org/c/16335, /c/19197, /c/29697, /c/60319.

Author: Timothy Redaelli

TMessagesProj/jni/tgnet/ConnectionSocket.cpp

@@ -496,11 +496,6 @@ void ConnectionSocket::openConnection(std::string address, uint16_t port, std::s
 
     if (!proxyAddress->empty()) {
         if (LOGS_ENABLED) DEBUG_D("connection(%p) connecting via proxy %s:%d secret[%d]", this, proxyAddress->c_str(), proxyPort, (int) proxySecret->size());
-        if ((socketFd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
-            if (LOGS_ENABLED) DEBUG_E("connection(%p) can't create proxy socket", this);
-            closeSocket(1, -1);
-            return;
-        }
         uint32_t tempBuffLength;
         if (proxySecret->empty()) {
             proxyAuthState = 1;
@@ -524,6 +519,8 @@ void ConnectionSocket::openConnection(std::string address, uint16_t port, std::s
         }
         socketAddress.sin_family = AF_INET;
         socketAddress.sin_port = htons(proxyPort);
+        socketAddress6.sin6_family = AF_INET6;
+        socketAddress6.sin6_port = htons(proxyPort);
         bool continueCheckAddress;
         if (inet_pton(AF_INET, proxyAddress->c_str(), &socketAddress.sin_addr.s_addr) != 1) {
             continueCheckAddress = true;
@@ -567,11 +564,6 @@ void ConnectionSocket::openConnection(std::string address, uint16_t port, std::s
         }
     } else {
         proxyAuthState = 0;
-        if ((socketFd = socket(ipv6 ? AF_INET6 : AF_INET, SOCK_STREAM, 0)) < 0) {
-            if (LOGS_ENABLED) DEBUG_E("connection(%p) can't create socket", this);
-            closeSocket(1, -1);
-            return;
-        }
         if (ipv6) {
             socketAddress6.sin6_family = AF_INET6;
             socketAddress6.sin6_port = htons(port);
@@ -613,6 +605,11 @@ void ConnectionSocket::openConnection(std::string address, uint16_t port, std::s
 }
 
 void ConnectionSocket::openConnectionInternal(bool ipv6) {
+    if ((socketFd = socket(ipv6 ? AF_INET6 : AF_INET, SOCK_STREAM, 0)) < 0) {
+        if (LOGS_ENABLED) DEBUG_E("connection(%p) can't create socket", this);
+        closeSocket(1, -1);
+        return;
+    }
     int epolFd = ConnectionsManager::getInstance(instanceNum).epolFd;
     int yes = 1;
     if (setsockopt(socketFd, IPPROTO_TCP, TCP_NODELAY, &yes, sizeof(int))) {
@@ -1150,16 +1147,27 @@ void ConnectionSocket::setOverrideProxy(std::string address, uint16_t port, std:
 }
 
 void ConnectionSocket::onHostNameResolved(std::string host, std::string ip, bool ipv6) {
-    ConnectionsManager::getInstance(instanceNum).scheduleTask([&, host, ip, ipv6] {
+    (void) ipv6;
+    ConnectionsManager::getInstance(instanceNum).scheduleTask([&, host, ip] {
         if (waitingForHostResolve == host) {
             waitingForHostResolve = "";
-            if (ip.empty() || inet_pton(AF_INET, ip.c_str(), &socketAddress.sin_addr.s_addr) != 1) {
+            if (ip.empty()) {
+                if (LOGS_ENABLED) DEBUG_E("connection(%p) can't resolve host %s address via delegate", this, host.c_str());
+                closeSocket(1, -1);
+                return;
+            }
+            bool resolvedIpv6;
+            if (inet_pton(AF_INET, ip.c_str(), &socketAddress.sin_addr.s_addr) == 1) {
+                resolvedIpv6 = false;
+            } else if (inet_pton(AF_INET6, ip.c_str(), &socketAddress6.sin6_addr.s6_addr) == 1) {
+                resolvedIpv6 = true;
+            } else {
                 if (LOGS_ENABLED) DEBUG_E("connection(%p) can't resolve host %s address via delegate", this, host.c_str());
                 closeSocket(1, -1);
                 return;
             }
             if (LOGS_ENABLED) DEBUG_D("connection(%p) resolved host %s address %s via delegate", this, host.c_str(), ip.c_str());
-            openConnectionInternal(ipv6);
+            openConnectionInternal(resolvedIpv6);
         }
     });
 }