commit c08948c8b831a2ba73c676b48aa11ba1b58cc542

Author: Tomas Korbar <tkorbar@redhat.com>

Date:   Thu Dec 8 11:03:08 2022 +0100

    Backport adding IP_BIND_ADDRESS_NO_PORT flag to outgoing connections

diff --git a/src/comm.cc b/src/comm.cc

index 0d5f34d..6811b54 100644

--- a/src/comm.cc

+++ b/src/comm.cc

@@ -58,6 +58,7 @@

  */

 static IOCB commHalfClosedReader;

+static int comm_openex(int sock_type, int proto, Ip::Address &, int flags, const char *note);

 static void comm_init_opened(const Comm::ConnectionPointer &conn, const char *note, struct addrinfo *AI);

 static int comm_apply_flags(int new_socket, Ip::Address &addr, int flags, struct addrinfo *AI);

@@ -75,6 +76,7 @@ static EVH commHalfClosedCheck;

 static void commPlanHalfClosedCheck();

 static Comm::Flag commBind(int s, struct addrinfo &);

+static void commSetBindAddressNoPort(int);

 static void commSetReuseAddr(int);

 static void commSetNoLinger(int);

 #ifdef TCP_NODELAY

@@ -201,6 +203,22 @@ comm_local_port(int fd)

     return F->local_addr.port();

 }

+/// sets the IP_BIND_ADDRESS_NO_PORT socket option to optimize ephemeral port

+/// reuse by outgoing TCP connections that must bind(2) to a source IP address

+static void

+commSetBindAddressNoPort(const int fd)

+{

+#if defined(IP_BIND_ADDRESS_NO_PORT)

+    int flag = 1;

+    if (setsockopt(fd, IPPROTO_IP, IP_BIND_ADDRESS_NO_PORT, reinterpret_cast<char*>(&flag), sizeof(flag)) < 0) {

+        const auto savedErrno = errno;

+        debugs(50, DBG_IMPORTANT, "ERROR: setsockopt(IP_BIND_ADDRESS_NO_PORT) failure: " << xstrerr(savedErrno));

+    }

+#else

+    (void)fd;

+#endif

+}

+

 static Comm::Flag

 commBind(int s, struct addrinfo &inaddr)

 {

@@ -227,6 +245,10 @@ comm_open(int sock_type,

           int flags,

           const char *note)

 {

+    // assume zero-port callers do not need to know the assigned port right away

+    if (sock_type == SOCK_STREAM && addr.port() == 0 && ((flags & COMM_DOBIND) || !addr.isAnyAddr()))

+        flags |= COMM_DOBIND_PORT_LATER;

+

     return comm_openex(sock_type, proto, addr, flags, note);

 }

@@ -328,7 +350,7 @@ comm_set_transparent(int fd)

  * Create a socket. Default is blocking, stream (TCP) socket.  IO_TYPE

  * is OR of flags specified in defines.h:COMM_*

  */

-int

+static int

 comm_openex(int sock_type,

             int proto,

             Ip::Address &addr,

@@ -476,6 +498,9 @@ comm_apply_flags(int new_socket,

         if ( addr.isNoAddr() )

             debugs(5,0,"CRITICAL: Squid is attempting to bind() port " << addr << "!!");

+        if ((flags & COMM_DOBIND_PORT_LATER))

+            commSetBindAddressNoPort(new_socket);

+

         if (commBind(new_socket, *AI) != Comm::OK) {

             comm_close(new_socket);

             return -1;

diff --git a/src/comm.h b/src/comm.h

index c963e1c..9ff201d 100644

--- a/src/comm.h

+++ b/src/comm.h

@@ -43,7 +43,6 @@ void comm_import_opened(const Comm::ConnectionPointer &, const char *note, struc

 /**

  * Open a port specially bound for listening or sending through a specific port.

- * This is a wrapper providing IPv4/IPv6 failover around comm_openex().

  * Please use for all listening sockets and bind() outbound sockets.

  *

  * It will open a socket bound for:

@@ -59,7 +58,6 @@ void comm_import_opened(const Comm::ConnectionPointer &, const char *note, struc

 int comm_open_listener(int sock_type, int proto, Ip::Address &addr, int flags, const char *note);

 void comm_open_listener(int sock_type, int proto, Comm::ConnectionPointer &conn, const char *note);

-int comm_openex(int, int, Ip::Address &, int, const char *);

 unsigned short comm_local_port(int fd);

 int comm_udp_sendto(int sock, const Ip::Address &to, const void *buf, int buflen);

diff --git a/src/comm/ConnOpener.cc b/src/comm/ConnOpener.cc

index 25a30e4..2082214 100644

--- a/src/comm/ConnOpener.cc

+++ b/src/comm/ConnOpener.cc

@@ -263,7 +263,7 @@ Comm::ConnOpener::createFd()

     if (callback_ == NULL || callback_->canceled())

         return false;

-    temporaryFd_ = comm_openex(SOCK_STREAM, IPPROTO_TCP, conn_->local, conn_->flags, host_);

+    temporaryFd_ = comm_open(SOCK_STREAM, IPPROTO_TCP, conn_->local, conn_->flags, host_);

     if (temporaryFd_ < 0) {

         sendAnswer(Comm::ERR_CONNECT, 0, "Comm::ConnOpener::createFd");

         return false;

diff --git a/src/comm/Connection.h b/src/comm/Connection.h

index 4f2f23a..1e32c22 100644

--- a/src/comm/Connection.h

+++ b/src/comm/Connection.h

@@ -47,6 +47,8 @@ namespace Comm

 #define COMM_DOBIND             0x08  // requires a bind()

 #define COMM_TRANSPARENT        0x10  // arrived via TPROXY

 #define COMM_INTERCEPTION       0x20  // arrived via NAT

+/// Internal Comm optimization: Keep the source port unassigned until connect(2)

+#define COMM_DOBIND_PORT_LATER 0x100

 /**

  * Store data about the physical and logical attributes of a connection.

diff --git a/src/ipc.cc b/src/ipc.cc

index e1d48fc..e92a27f 100644

--- a/src/ipc.cc

+++ b/src/ipc.cc

@@ -95,12 +95,12 @@ ipcCreate(int type, const char *prog, const char *const args[], const char *name

     } else void(0)

     if (type == IPC_TCP_SOCKET) {

-        crfd = cwfd = comm_open(SOCK_STREAM,

+        crfd = cwfd = comm_open_listener(SOCK_STREAM,

                                 0,

                                 local_addr,

                                 COMM_NOCLOEXEC,

                                 name);

-        prfd = pwfd = comm_open(SOCK_STREAM,

+        prfd = pwfd = comm_open_listener(SOCK_STREAM,

                                 0,          /* protocol */

                                 local_addr,

                                 0,          /* blocking */

diff --git a/src/tests/stub_comm.cc b/src/tests/stub_comm.cc

index 58f85e4..5381ab2 100644

--- a/src/tests/stub_comm.cc

+++ b/src/tests/stub_comm.cc

@@ -46,7 +46,6 @@ int comm_open_uds(int sock_type, int proto, struct sockaddr_un* addr, int flags)

 void comm_import_opened(const Comm::ConnectionPointer &, const char *note, struct addrinfo *AI) STUB

 int comm_open_listener(int sock_type, int proto, Ip::Address &addr, int flags, const char *note) STUB_RETVAL(-1)

 void comm_open_listener(int sock_type, int proto, Comm::ConnectionPointer &conn, const char *note) STUB

-int comm_openex(int, int, Ip::Address &, int, tos_t tos, nfmark_t nfmark, const char *) STUB_RETVAL(-1)

 unsigned short comm_local_port(int fd) STUB_RETVAL(0)

 int comm_udp_sendto(int sock, const Ip::Address &to, const void *buf, int buflen) STUB_RETVAL(-1)

 void commCallCloseHandlers(int fd) STUB