[llvm-jitlink] Replace use of deprecated gethostbyname by getaddrinfo.

[saghir]

Summary

This patch replaces use of deprecated gethostbyname by getaddrinfo.

Author: Rafik Zurob

[rzurob]

llvm/tools/llvm-jitlink/llvm-jitlink.cpp

694

IIRC, this syntax didn't build for me on Linux. I suggest this instead: addrinfo Hints{};

[saghir]

Address comments:
Changed addrinfo Hints = {}; to addrinfo Hints{};

[saghir]

llvm/tools/llvm-jitlink/llvm-jitlink.cpp

694

Thanks for catching that. I was able to build with this on Ubuntu and RHEL(7.6 & 8.2). I believe the one that did not build was addrinfo Hints = {0};. I have changed this to addrinfo Hints{}; now.

[tschuett]

The man page uses:

memset(Hints, 0, sizeof(Hints));

https://man7.org/linux/man-pages/man3/getaddrinfo.3.html

[rzurob]

In D95477#2523851, @tschuett wrote:

The man page uses:

memset(Hints, 0, sizeof(Hints));

https://man7.org/linux/man-pages/man3/getaddrinfo.3.html

The POSIX specification discourages using memset to initialize addrinfo for portability reasons.
https://pubs.opengroup.org/onlinepubs/9699919799/functions/getaddrinfo.html
Under "Application Usage", it says:

Although it is common practice to initialize the hints structure using:

struct addrinfo hints;
memset(&hints, 0, sizeof hints);

this method is not portable according to this standard, because the structure can contain pointer or floating-point members that are not required to have an all-bits-zero representation after default initialization. Portable methods make use of default initialization; for example:

struct addrinfo hints = { 0 };

or:

static struct addrinfo hints_init;
struct addrinfo hints = hints_init;

[lhames]

This is a nice improvement, thanks!

llvm/tools/llvm-jitlink/llvm-jitlink.cpp

#else
 
   std::string HostName = HostNameStr.str();
   int Port = 0;
   if (PortStr.getAsInteger(10, Port))
     return make_error<StringError>("port number " + PortStr +
                                        " is not a valid integer",
                                    inconvertibleErrorCode());
 
+  addrinfo *AI;
+  addrinfo Hints{};
+  Hints.ai_family = AF_INET;
+  Hints.ai_socktype = SOCK_STREAM;
+  Hints.ai_protocol = PF_INET;
+  Hints.ai_flags = AI_NUMERICSERV;
+  if (getaddrinfo(HostName.c_str(), PortStr.str().c_str(), &Hints, &AI) != 0)
+    return make_error<StringError>("Failed to resolve " + HostName + ":" +
+                                       Twine(Port),
+                                   inconvertibleErrorCode());
+
   int SockFD = socket(PF_INET, SOCK_STREAM, 0);
-  hostent *Server = gethostbyname(HostName.c_str());
   sockaddr_in ServAddr;
   memset(&ServAddr, 0, sizeof(ServAddr));
   ServAddr.sin_family = PF_INET;
-  memmove(&Server->h_addr, &ServAddr.sin_addr.s_addr, Server->h_length);
   ServAddr.sin_port = htons(Port);
-  if (connect(SockFD, reinterpret_cast<sockaddr *>(&ServAddr),
-              sizeof(ServAddr)) < 0)
+
+  // getaddrinfo returns a list of address structures.  Go through the list
+  // to find one we can connect to.
+  int ConnectRC = -1;
+  for (addrinfo *Server = AI; Server; Server = Server->ai_next) {
+    memmove(&Server->ai_addr, &ServAddr.sin_addr.s_addr, Server->ai_addrlen);
+    ConnectRC = connect(SockFD, reinterpret_cast<sockaddr *>(&ServAddr),
+                        sizeof(ServAddr));
+    if (ConnectRC == 0)
+      break;
+  }
+  freeaddrinfo(AI);
+  if (ConnectRC == -1)
     return make_error<StringError>("Failed to connect to " + HostName + ":" +
                                        Twine(Port),
                                    inconvertibleErrorCode());
 
   auto SSP = std::make_shared<SymbolStringPool>();
   auto Channel = std::make_unique<shared::FDRawByteChannel>(SockFD, SockFD);
   auto Endpoint = std::make_unique<LLVMJITLinkRPCEndpoint>(*Channel, true);