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Add hint SDL_NET_HINT_IP_DEFAULT_VERSION to select IPv6 or IPv4 #120

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Add hint SDL_NET_HINT_IP_DEFAULT_VERSION to select IPv6 or IPv4 #120

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6c3c3b0
create hint SDL_NET_HINT_IP_DEFAULT_VERSION
mkunkacnc Feb 15, 2025
171a418
Also use SDL_NET_HINT_IP_DEFAULT_VERSION in ResolveAddress
mkunkacnc Feb 15, 2025
d515bff
tweek comment
mkunkacnc Feb 15, 2025
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9 changes: 9 additions & 0 deletions include/SDL3_net/SDL_net.h
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Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,15 @@ extern "C" {
(SDL_NET_MAJOR_VERSION > X || SDL_NET_MINOR_VERSION >= Y) && \
(SDL_NET_MAJOR_VERSION > X || SDL_NET_MINOR_VERSION > Y || SDL_NET_MICRO_VERSION >= Z))

/**
* A variable setting the default IP value to "IPv4" or "IPv6"
*
* This hint should be set before creating a socket bound to a NULL address
* and before resolving a hostname.
*
* \since This hint is available since SDL_net 3.0.0
*/
#define SDL_NET_HINT_IP_DEFAULT_VERSION "SDL_NET_HINT_IP_DEFAULT_VERSION"

/**
* This function gets the version of the dynamically linked SDL_net library.
Expand Down
31 changes: 28 additions & 3 deletions src/SDL_net.c
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Original file line number Diff line number Diff line change
Expand Up @@ -160,7 +160,7 @@ static char *CreateSocketErrorString(int rc)
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), /* Default language */
msgbuf,
SDL_arraysize(msgbuf),
NULL
NULL
);
if (bw == 0) {
return SDL_strdup("Unknown error");
Expand Down Expand Up @@ -220,8 +220,23 @@ static int ResolveAddress(SDLNet_Address *addr)
struct addrinfo *ainfo = NULL;
int rc;

struct addrinfo hints, *phints = &hints;
SDL_zero(hints);

const char *hint = SDL_GetHint(SDL_NET_HINT_IP_DEFAULT_VERSION);
if (hint) {
if (SDL_strcasecmp(hint, "ipv4") == 0) {
hints.ai_family = AF_INET;
} else if (SDL_strcasecmp(hint, "ipv6") == 0) {
hints.ai_family = AF_INET6;
hints.ai_flags = AI_V4MAPPED;
}
} else {
phints = NULL;
}

//SDL_Log("getaddrinfo '%s'", addr->hostname);
rc = getaddrinfo(addr->hostname, NULL, NULL, &ainfo);
rc = getaddrinfo(addr->hostname, NULL, phints, &ainfo);
//SDL_Log("rc=%d", rc);
if (rc != 0) {
addr->errstr = CreateGetAddrInfoErrorString(rc);
Expand Down Expand Up @@ -279,7 +294,7 @@ static int SDLCALL ResolverThread(void *data)

int outcome;
if (!simulated_loss || (RandomNumberBetween(0, 100) > simulated_loss)) {
outcome = ResolveAddress(addr);
outcome = ResolveAddress(addr);
} else {
outcome = -1;
addr->errstr = SDL_strdup("simulated failure");
Expand Down Expand Up @@ -779,6 +794,16 @@ static struct addrinfo *MakeAddrInfoWithPort(const SDLNet_Address *addr, const i
//hints.ai_protocol = ainfo ? ainfo->ai_protocol : 0;
hints.ai_flags = AI_NUMERICHOST | AI_NUMERICSERV | (!ainfo ? AI_PASSIVE : 0);

const char *hint = SDL_GetHint(SDL_NET_HINT_IP_DEFAULT_VERSION);
if (!addr && hint) {
if (SDL_strcasecmp(hint, "ipv4") == 0) {
hints.ai_family = AF_INET;
} else if (SDL_strcasecmp(hint, "ipv6") == 0) {
hints.ai_family = AF_INET6;
hints.ai_flags |= AI_V4MAPPED;
}
}

char service[16];
SDL_snprintf(service, sizeof (service), "%d", (int) port);

Expand Down
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