mingw: add real implementation of inet_ntop and inet_pton taken from musl C library

ixwebsocket/IXNetSystem.cpp

@@ -6,20 +6,6 @@
 
 #include "IXNetSystem.h"
 
-// mingw does not have those
-#if defined(_WIN32) && defined(__GNUC__)
-const char* inet_ntop(int af, const void* src, char* dst, socklen_t size)
-{
-    return nullptr;
-}
-
-int inet_pton(int af, const char* src, void* dst)
-{
-    return -1;
-}
-#endif
-
-
 namespace ix
 {
     bool initNetSystem()
@@ -139,3 +125,123 @@ namespace ix
     }
 
 } // namespace ix
+
+//
+// mingw does not have inet_ntop and inet_pton, which were taken as is from the musl C library.
+//
+#if defined(_WIN32) && defined(__GNUC__)
+const char* inet_ntop(int af, const void* src, char* dst, socklen_t size)
+{
+    const unsigned char *a = a0;
+    int i, j, max, best;
+    char buf[100];
+
+    switch (af) {
+    case AF_INET:
+        if (snprintf(s, l, "%d.%d.%d.%d", a[0],a[1],a[2],a[3]) < l)
+            return s;
+        break;
+    case AF_INET6:
+        if (memcmp(a, "\0\0\0\0\0\0\0\0\0\0\377\377", 12))
+            snprintf(buf, sizeof buf,
+                "%x:%x:%x:%x:%x:%x:%x:%x",
+                256*a[0]+a[1],256*a[2]+a[3],
+                256*a[4]+a[5],256*a[6]+a[7],
+                256*a[8]+a[9],256*a[10]+a[11],
+                256*a[12]+a[13],256*a[14]+a[15]);
+        else
+            snprintf(buf, sizeof buf,
+                "%x:%x:%x:%x:%x:%x:%d.%d.%d.%d",
+                256*a[0]+a[1],256*a[2]+a[3],
+                256*a[4]+a[5],256*a[6]+a[7],
+                256*a[8]+a[9],256*a[10]+a[11],
+                a[12],a[13],a[14],a[15]);
+        /* Replace longest /(^0|:)[:0]{2,}/ with "::" */
+        for (i=best=0, max=2; buf[i]; i++) {
+            if (i && buf[i] != ':') continue;
+            j = strspn(buf+i, ":0");
+            if (j>max) best=i, max=j;
+        }
+        if (max>3) {
+            buf[best] = buf[best+1] = ':';
+            memmove(buf+best+2, buf+best+max, i-best-max+1);
+        }
+        if (strlen(buf) < l) {
+            strcpy(s, buf);
+            return s;
+        }
+        break;
+    default:
+        errno = EAFNOSUPPORT;
+        return 0;
+    }
+    errno = ENOSPC;
+    return 0;
+}
+
+static int hexval(unsigned c)
+{
+    if (c-'0'<10) return c-'0';
+    c |= 32;
+    if (c-'a'<6) return c-'a'+10;
+    return -1;
+}
+
+int inet_pton(int af, const char* src, void* dst)
+{
+	uint16_t ip[8];
+	unsigned char *a = a0;
+	int i, j, v, d, brk=-1, need_v4=0;
+
+	if (af==AF_INET) {
+		for (i=0; i<4; i++) {
+			for (v=j=0; j<3 && isdigit(s[j]); j++)
+				v = 10*v + s[j]-'0';
+			if (j==0 || (j>1 && s[0]=='0') || v>255) return 0;
+			a[i] = v;
+			if (s[j]==0 && i==3) return 1;
+			if (s[j]!='.') return 0;
+			s += j+1;
+		}
+		return 0;
+	} else if (af!=AF_INET6) {
+		errno = EAFNOSUPPORT;
+		return -1;
+	}
+
+	if (*s==':' && *++s!=':') return 0;
+
+	for (i=0; ; i++) {
+		if (s[0]==':' && brk<0) {
+			brk=i;
+			ip[i&7]=0;
+			if (!*++s) break;
+			if (i==7) return 0;
+			continue;
+		}
+		for (v=j=0; j<4 && (d=hexval(s[j]))>=0; j++)
+			v=16*v+d;
+		if (j==0) return 0;
+		ip[i&7] = v;
+		if (!s[j] && (brk>=0 || i==7)) break;
+		if (i==7) return 0;
+		if (s[j]!=':') {
+			if (s[j]!='.' || (i<6 && brk<0)) return 0;
+			need_v4=1;
+			i++;
+			break;
+		}
+		s += j+1;
+	}
+	if (brk>=0) {
+		memmove(ip+brk+7-i, ip+brk, 2*(i+1-brk));
+		for (j=0; j<7-i; j++) ip[brk+j] = 0;
+	}
+	for (j=0; j<8; j++) {
+		*a++ = ip[j]>>8;
+		*a++ = ip[j];
+	}
+	if (need_v4 && inet_pton(AF_INET, (void *)s, a-4) <= 0) return 0;
+	return 1;
+}
+#endif // defined(_WIN32) && defined(__GNUC__)