Diff: udp/dns/dnslabel.c

Revision:

128:79052cb4a41c

Child:

182:ff48c6ea91c1

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/udp/dns/dnslabel.c	Mon Mar 11 16:42:45 2019 +0000
@@ -0,0 +1,95 @@
+#include <stdbool.h>
+#include <string.h>
+
+#include "dns.h"
+#include "dnslabel.h"
+#include "dhcp.h"
+
+void DnsLabelCopy(char* dst, char* src)
+{
+    strncpy(dst, src, DNS_MAX_LABEL_LENGTH); //Copies up to 63 bytes
+    dst[DNS_MAX_LABEL_LENGTH] = 0; //dst[63] is the 64th position from 0..63 is set to null. All labels must be declared as a size of 64
+}
+
+bool DnsLabelIsSame(char* pA, char* pB)
+{
+    while(true)
+    {
+        char a = *pA++;
+        char b = *pB++;
+        if (a >= 'A' && a <= 'Z') a |= 0x20; //Make lower case
+        if (b >= 'A' && b <= 'Z') b |= 0x20; //Make lower case
+        if (a != b) return false;            //If different then stop and return the fact
+        if (!a) break;                       //No need to check 'b' too as it will necessarily be equal to 'a' at this point.
+    }
+    return true;                             //If we get here the strings must equate.
+}
+
+int DnsLabelMakeFullNameFromName(int protocol, const char* p, int size, char* result)
+{
+    int i = 0;
+    char c;
+    
+    while (i < size - 1)
+    {
+        c = *p++;
+        if (!c) break;
+        *result++ = c;
+        i++;
+    }
+    if (protocol == DNS_PROTOCOL_MDNS)
+    {
+        p = ".local";
+        while (i < size - 1)
+        {
+            c = *p++;
+            if (!c) break;
+            *result++ = c;
+            i++;
+        }
+    }
+    if (protocol == DNS_PROTOCOL_UDNS && DhcpDomainName[0]) //Shouldn't do this in IPv6 as DHCP is IPv4 only
+    {
+        if (i < size - 1)
+        {
+            *result++ = '.';
+            i++;
+        }
+        p = DhcpDomainName;
+        while (i < size - 1)
+        {
+            c = *p++;
+            if (!c) break;
+            *result++ = c;
+            i++;
+        }
+    }
+    *result = 0; //Terminate the resulting string
+    return i;
+}
+int DnsLabelStripNameFromFullName(int protocol, char* p, int size, char* result)
+{
+    int i = 0;
+    char c;
+    
+    while (i < size - 1)
+    {
+        c = *p++;
+        if (c == 0)   break;                               //End of the fqdn so stop
+        if (c == '.')
+        {
+            if (protocol == DNS_PROTOCOL_UDNS)
+            {
+                if (strcmp(p, DhcpDomainName) == 0) break; //Strip the domain from a UDNS fqdn if, and only if, it matches the domain given in DHCP. IPv4 only.
+            }
+            else
+            {
+                break;                                     //Strip the domain from an LLMNR (there shouldn't be one) or MDNS (it should always be '.local') fqdn
+            }
+        }
+        *result++ = c;
+        i++;
+    }
+    *result = 0;           //Terminate the copied string
+    return i;
+}