Unified sockaddr->SDLNet_Address code, implemented SDLNet_GetLocalAdd…

…resses.

Added an example app for SDLNet_GetLocalAddresses.

This commit is not tested on, or even compiled for, Windows yet.

CMakeLists.txt

@@ -32,3 +32,6 @@ target_link_libraries(simple-http-get PRIVATE SDL3_net::SDL3_net SDL3::SDL3)
 
 add_executable(resolve-hostnames examples/resolve-hostnames.c)
 target_link_libraries(resolve-hostnames PRIVATE SDL3_net::SDL3_net SDL3::SDL3)
+
+add_executable(get-local-addrs examples/get-local-addrs.c)
+target_link_libraries(get-local-addrs PRIVATE SDL3_net::SDL3_net SDL3::SDL3)

SDL_net.c

@@ -5,6 +5,7 @@
 #define _WIN32_WINNT 0x0600 /* we need APIs that didn't arrive until Windows Vista. */
 #include <winsock2.h>
 #include <ws2tcpip.h>
+#include <iphlpapi.h>
 typedef SOCKET Socket;
 typedef int SockLen;
 typedef SOCKADDR_STORAGE AddressStorage;
@@ -24,8 +25,6 @@ static int read(SOCKET s, char *buf, size_t count) {
  }
  return (int)count_received;
 }
-
-#define EAI_SYSTEM 0
 #define poll WSAPoll
 #else
 #include <sys/types.h>
@@ -38,6 +37,7 @@ static int read(SOCKET s, char *buf, size_t count) {
 #include <poll.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <ifaddrs.h>
 #define INVALID_SOCKET -1
 #define SOCKET_ERROR -1
 typedef int Socket;
@@ -126,7 +126,7 @@ static char *CreateSocketErrorString(int rc)
  FORMAT_MESSAGE_FROM_SYSTEM |
  FORMAT_MESSAGE_IGNORE_INSERTS,
  NULL,
- err,
+ rc,
  MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), /* Default language */
  msgbuf,
  SDL_arraysize(msgbuf),
@@ -288,6 +288,48 @@ static void DestroyAddress(SDLNet_Address *addr)
  }
 }
 
+static SDLNet_Address *CreateSDLNetAddrFromSockAddr(struct sockaddr *saddr, SockLen saddrlen)
+{
+ // !!! FIXME: this all seems inefficient in the name of keeping addresses generic.
+ char hostbuf[128];
+ int gairc = getnameinfo(saddr, saddrlen, hostbuf, sizeof (hostbuf), NULL, 0, NI_NUMERICHOST);
+ if (gairc != 0) {
+ SetGetAddrInfoError("Failed to determine address", gairc);
+ return NULL;
+ }
+
+ SDLNet_Address *addr = (SDLNet_Address *) SDL_calloc(1, sizeof (SDLNet_Address));
+ if (!addr) {
+ SDL_OutOfMemory();
+ return NULL;
+ }
+ SDL_AtomicSet(&addr->status, 1);
+
+ struct addrinfo hints;
+ SDL_zero(hints);
+ hints.ai_family = saddr->sa_family;
+ hints.ai_socktype = SOCK_DGRAM;
+ hints.ai_protocol = 0;
+ hints.ai_flags = AI_NUMERICHOST;
+
+ gairc = getaddrinfo(hostbuf, NULL, &hints, &addr->ainfo);
+ if (gairc != 0) {
+ SDL_free(addr);
+ SetGetAddrInfoError("Failed to determine address", gairc);
+ return NULL;
+ }
+
+ addr->human_readable = SDL_strdup(hostbuf);
+ if (!addr->human_readable) {
+ freeaddrinfo(addr->ainfo);
+ SDL_free(addr);
+ SDL_OutOfMemory();
+ return NULL;
+ }
+
+ return SDLNet_RefAddress(addr);
+}
+
 int SDLNet_Init(void)
 {
  char *origerrstr = NULL;
@@ -528,8 +570,118 @@ void SDLNet_SimulateAddressResolutionLoss(int percent_loss)
 
 SDLNet_Address **SDLNet_GetLocalAddresses(int *num_addresses)
 {
- // !!! FIXME: write me!
- return NULL;
+ int count = 0;
+ SDLNet_Address **retval = NULL;
+
+ *num_addresses = 0;
+
+#ifdef __WINDOWS__
+ // !!! FIXME: maybe LoadLibrary(iphlpapi) on the first call, since most
+ // !!! FIXME: things won't ever use this.
+
+ // MSDN docs say start with a 15K buffer, which usually works on the first
+ // try, instead of trying to query for size, allocate, and then retry,
+ // since this tends to be more expensive.
+ ULONG buflen = 15 * 1024;
+ IP_ADAPTER_ADDRESSES *addrs = NULL;
+ ULONG rc;
+
+ do {
+ SDL_free(addrs);
+ addrs = (IP_ADAPTER_ADDRESSES *) SDL_malloc(buflen);
+ if (!addrs) {
+ SDL_OutOfMemory();
+ return NULL;
+ }
+
+ const ULONG flags = GAA_FLAG_SKIP_DNS_SERVER | GAA_FLAG_SKIP_FRIENDLY_NAME;
+ rc = GetAdaptersAddresses(AF_UNSPEC, flags, NULL, addrs, &buflen);
+ } while (rc == ERROR_BUFFER_OVERFLOW);
+
+ if (rc != NO_ERROR) {
+ SetSocketError("GetAdaptersAddresses failed", rc);
+ SDL_free(addrs);
+ return NULL;
+ }
+
+ for (IP_ADAPTER_ADDRESSES *i = addrs; i != NULL; i = i->Next) {
+ for (IP_ADAPTER_UNICAST_ADDRESS *j = i->FirstUnicastAddress; j != NULL; j = j->Next) {
+ count++;
+ }
+ }
+
+ retval = (SDLNet_Address **) SDL_calloc(count + 1, sizeof (SDLNet_Address *));
+ if (!retval) {
+ SDL_OutOfMemory();
+ SDL_free(addrs);
+ return NULL;
+ }
+
+ count = 0;
+ for (IP_ADAPTER_ADDRESSES *i = addrs; i != NULL; i = i->Next) {
+ for (IP_ADAPTER_UNICAST_ADDRESS *j = i->FirstUnicastAddress; j != NULL; j = j->Next) {
+ SDLNet_Address *addr = CreateSDLNetAddrFromSockAddr(j->Address.lpSockaddr, j->Address.iSockaddrLength);
+ if (addr) {
+ retval[count++] = addr;
+ }
+ }
+ }
+
+ SDL_free(addrs);
+
+#else
+ struct ifaddrs *ifaddr;
+ if (getifaddrs(&ifaddr) == -1) {
+ SDL_SetError("getifaddrs failed: %s", strerror(errno));
+ return NULL; // oh well.
+ }
+
+ for (struct ifaddrs *i = ifaddr; i != NULL; i = i->ifa_next) {
+ if (i->ifa_name != NULL) {
+ count++;
+ }
+ }
+
+ retval = (SDLNet_Address **) SDL_calloc(count + 1, sizeof (SDLNet_Address *));
+ if (!retval) {
+ if (ifaddr) {
+ freeifaddrs(ifaddr);
+ }
+ SDL_OutOfMemory();
+ return NULL;
+ }
+
+ count = 0;
+ for (struct ifaddrs *i = ifaddr; i != NULL; i = i->ifa_next) {
+ if (i->ifa_name != NULL) {
+ SDLNet_Address *addr = NULL;
+ // !!! FIXME: getifaddrs doesn't return the sockaddr length, so we have to go with known protocols. :/
+ if (i->ifa_addr->sa_family == AF_INET) {
+ addr = CreateSDLNetAddrFromSockAddr(i->ifa_addr, sizeof (struct sockaddr_in));
+ } else if (i->ifa_addr->sa_family == AF_INET6) {
+ addr = CreateSDLNetAddrFromSockAddr(i->ifa_addr, sizeof (struct sockaddr_in6));
+ }
+
+ if (addr) {
+ retval[count++] = addr;
+ }
+ }
+ }
+
+ if (ifaddr) {
+ freeifaddrs(ifaddr);
+ }
+#endif
+
+ *num_addresses = count;
+
+ // try to shrink allocation.
+ void *ptr = SDL_realloc(retval, (count + 1) * sizeof (SDLNet_Address *));
+ if (ptr) {
+ retval = (SDLNet_Address **) ptr;
+ }
+
+ return retval;
 }
 
 void SDLNet_FreeLocalAddresses(SDLNet_Address **addresses)
@@ -793,49 +945,22 @@ int SDLNet_AcceptClient(SDLNet_Server *server, SDLNet_StreamSocket **client_stre
  return SDL_SetError("Failed to make incoming socket non-blocking");
  }
 
- // !!! FIXME: this all seems inefficient in the name of keeping addresses generic.
- char hostbuf[128];
  char portbuf[16];
- const int rc = getnameinfo((struct sockaddr *) &from, fromlen, hostbuf, sizeof (hostbuf), portbuf, sizeof (portbuf), NI_NUMERICHOST | NI_NUMERICSERV);
- if (rc != 0) {
- CloseSocketHandle(handle);
- return SetGetAddrInfoError("Failed to determine incoming connection's address", rc);
- }
-
- SDLNet_Address *fromaddr = (SDLNet_Address *) SDL_calloc(1, sizeof (SDLNet_Address));
- if (!fromaddr) {
- CloseSocketHandle(handle);
- return SDL_OutOfMemory();
- }
- SDL_AtomicSet(&fromaddr->status, 1);
-
- struct addrinfo hints;
- SDL_zero(hints);
- hints.ai_family = ((struct sockaddr *) &from)->sa_family;
- hints.ai_socktype = SOCK_DGRAM;
- hints.ai_protocol = 0;
- hints.ai_flags = AI_NUMERICHOST;
-
- const int gairc = getaddrinfo(hostbuf, NULL, &hints, &fromaddr->ainfo);
+ const int gairc = getnameinfo((struct sockaddr *) &from, fromlen, NULL, 0, portbuf, sizeof (portbuf), NI_NUMERICSERV);
  if (gairc != 0) {
- SDL_free(fromaddr);
  CloseSocketHandle(handle);
- return SetGetAddrInfoError("Failed to determine incoming connection's address: %s", rc);
+ return SetGetAddrInfoError("Failed to determine port number", gairc);
  }
 
- fromaddr->human_readable = SDL_strdup(hostbuf);
- if (!fromaddr->human_readable) {
- freeaddrinfo(fromaddr->ainfo);
- SDL_free(fromaddr);
+ SDLNet_Address *fromaddr = CreateSDLNetAddrFromSockAddr((struct sockaddr *) &from, fromlen);
+ if (!fromaddr) {
  CloseSocketHandle(handle);
- return SDL_OutOfMemory();
+ return -1; // error string was already set.
  }
 
  SDLNet_StreamSocket *sock = (SDLNet_StreamSocket *) SDL_calloc(1, sizeof (SDLNet_StreamSocket));
  if (!sock) {
- SDL_free(fromaddr->human_readable);
- freeaddrinfo(fromaddr->ainfo);
- SDL_free(fromaddr);
+ SDLNet_UnrefAddress(fromaddr);
  CloseSocketHandle(handle);
  return SDL_OutOfMemory();
  }
@@ -1261,7 +1386,6 @@ int SDLNet_ReceiveDatagram(SDLNet_DatagramSocket *sock, SDLNet_Datagram **dgram)
  return 0;
  }
 
- // !!! FIXME: this all seems inefficient in the name of keeping addresses generic.
  char hostbuf[128];
  char portbuf[16];
  const int rc = getnameinfo((struct sockaddr *) &from, fromlen, hostbuf, sizeof (hostbuf), portbuf, sizeof (portbuf), NI_NUMERICHOST | NI_NUMERICSERV);
@@ -1296,45 +1420,23 @@ int SDLNet_ReceiveDatagram(SDLNet_DatagramSocket *sock, SDLNet_Datagram **dgram)
 
  const SDL_bool create_fromaddr = (!fromaddr) ? SDL_TRUE : SDL_FALSE;
  if (create_fromaddr) {
- fromaddr = (SDLNet_Address *) SDL_calloc(1, sizeof (SDLNet_Address));
+ fromaddr = CreateSDLNetAddrFromSockAddr((struct sockaddr *) &from, fromlen);
  if (!fromaddr) {
- return SDL_OutOfMemory();
- }
- SDL_AtomicSet(&fromaddr->status, 1);
-
- struct addrinfo hints;
- SDL_zero(hints);
- hints.ai_family = ((struct sockaddr *) &from)->sa_family;
- hints.ai_socktype = SOCK_DGRAM;
- hints.ai_protocol = 0;
- hints.ai_flags = AI_NUMERICHOST;
-
- const int gairc = getaddrinfo(hostbuf, NULL, &hints, &fromaddr->ainfo);
- if (gairc != 0) {
- SDL_free(fromaddr);
- return SetGetAddrInfoError("Failed to determine incoming packet's address", gairc);
- }
-
- fromaddr->human_readable = SDL_strdup(hostbuf);
- if (!fromaddr->human_readable) {
- freeaddrinfo(fromaddr->ainfo);
- SDL_free(fromaddr);
- return SDL_OutOfMemory();
+ return -1; // already set the error string.
  }
  }
 
  SDLNet_Datagram *dg = SDL_malloc(sizeof (SDLNet_Datagram) + br);
  if (!dg) {
  if (create_fromaddr) {
- freeaddrinfo(fromaddr->ainfo);
- SDL_free(fromaddr);
+ SDLNet_UnrefAddress(fromaddr);
  }
  return SDL_OutOfMemory();
  }
 
  dg->buf = (Uint8 *) (dg+1);
  SDL_memcpy(dg->buf, sock->recv_buffer, br);
- dg->addr = SDLNet_RefAddress(fromaddr);
+ dg->addr = create_fromaddr ? fromaddr : SDLNet_RefAddress(fromaddr);
  dg->port = (Uint16) SDL_atoi(portbuf);
  dg->buflen = br;
 

examples/get-local-addrs.c

@@ -0,0 +1,40 @@
+/*
+ * This is just for demonstration purposes! This doesn't
+ * do anything as complicated as, say, the `ifconfig` utility.
+ *
+ * All this to say: don't use this for anything serious!
+ */
+
+#include <stdio.h>
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_main.h>
+#include "SDL_net.h"
+
+int main(int argc, char **argv)
+{
+ SDLNet_Address **addrs = NULL;
+ int num_addrs = 0;
+ int i;
+
+ if (SDLNet_Init() < 0) {
+ SDL_Log("SDLNet_Init() failed: %s", SDL_GetError());
+ return 1;
+ }
+
+ addrs = SDLNet_GetLocalAddresses(&num_addrs);
+ if (addrs == NULL) {
+ SDL_Log("Failed to determine local addresses: %s", SDL_GetError());
+ SDLNet_Quit();
+ return 1;
+ }
+
+ SDL_Log("We saw %d local addresses:", num_addrs);
+ for (i = 0; i < num_addrs; i++) {
+ SDL_Log(" - %s", SDLNet_GetAddressString(addrs[i]));
+ }
+
+ SDLNet_FreeLocalAddresses(addrs);
+ SDLNet_Quit();
+
+ return 0;
+}