From 249866e3d1e11dc72eaa1305f4bb479ded92ef38 Mon Sep 17 00:00:00 2001
From: Jannis Hoffmann <jannis@fehcom.de>
Date: Tue, 9 Jul 2024 13:58:20 +0200
Subject: reorganized file structure

Moved c files into src/.
Corrected VERSION file.
Removed BUILD and FILES.
---
 src/dnsstub/dns_rcip.c | 114 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 src/dnsstub/dns_rcip.c

(limited to 'src/dnsstub/dns_rcip.c')

diff --git a/src/dnsstub/dns_rcip.c b/src/dnsstub/dns_rcip.c
new file mode 100644
index 0000000..93b0daa
--- /dev/null
+++ b/src/dnsstub/dns_rcip.c
@@ -0,0 +1,114 @@
+#include "taia.h"
+#include "readclose.h"
+#include "byte.h"
+#include "ip.h"
+#include "env.h"
+#include "dnsresolv.h"
+#include "socket_if.h"
+
+/**
+	@file dns_rcip.c
+	@author djb, fefe, feh
+	@source ucspi-tcp
+	@brief DNS receive for query
+*/
+
+static stralloc data = {0};
+static stralloc ifname = {0};
+
+static int init(char ip[QUERY_MAXIPLEN],uint32 sid[QUERY_MAXNS])
+{
+  int i;
+  int j;
+  int k = 0;
+  int iplen = 0;
+  char *x;
+  char ip4[4];
+
+/* Read (compactified) IPv4|v6 addresses of resolvers
+   Store them in array IP with fixed length : 
+   ip(64) -> 16 IPv4 addresses (not used anymore)
+   ip(512) -> 16*2 IPv6 addresses (we use IPv4 mapped IPv6 addresses) 
+   sid(32) -> the scope for the respective IPv6 or 0
+*/
+  for (i = 0; i < QUERY_MAXNS; ++i) sid[i] = 0;
+
+  x = env_get("DNSCACHEIP");
+  if (x)
+    while (iplen <= 240 && *x != '\0') {
+      if (*x == ' ') 
+        ++x; 
+      else 
+        if ((i = ip6_ifscan(x,ip + iplen,&ifname))) {
+          if (ifname.len > 2) sid[k] = socket_getifidx(ifname.s);
+          iplen += 16; k++;
+          if (*(x += i) == '\0') break;
+        } 
+    }
+
+  if (!iplen) {
+    i = openreadclose("/etc/resolv.conf",&data,64);
+    if (i == -1) return DNS_INT;
+    if (i) {
+      if (!stralloc_append(&data,"\n")) return DNS_MEM;
+      i = 0;
+      for (j = 0; j < data.len; ++j)
+        if (data.s[j] == '\n') {
+          if (byte_equal("nameserver ",11,data.s + i) || byte_equal("nameserver\t",11,data.s + i)) {
+            i += 10; 
+            while ((data.s[i] == ' ') || (data.s[i] == '\t'))
+              i++; 
+            if (iplen <= 240) {
+              data.s[j] = '\0'; /* ip6_ifscan needs terminated string on input */
+              if (ip4_scan(data.s + i,ip4)) {
+                if (byte_equal(ip4,4,"\0\0\0\0"))
+                  byte_copy(ip4,4,"\177\0\0\1");
+                byte_copy(ip + iplen,12,V4mappedprefix);
+                byte_copy(ip + iplen + 12,4,ip4);
+                sid[k] = 0; iplen += 16; k++;
+              } else if (ip6_ifscan(data.s + i,ip + iplen,&ifname)) {
+                if (ifname.len > 2) sid[k] = socket_getifidx(ifname.s);
+                iplen += 16; k++;
+              }
+            }
+          }
+          i = j + 1;
+        }
+    }
+  }
+
+  if (!iplen) {
+    byte_copy(ip,16,"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1");
+    iplen = 16;
+  }
+  byte_zero(ip + iplen,QUERY_MAXIPLEN - iplen);
+  return 0;
+}
+
+static int ok = 0;
+static unsigned int uses;
+static struct taia deadline;
+static char ip[QUERY_MAXIPLEN]; /* defined if ok */
+static uint32 scopes[QUERY_MAXNS]; 
+
+int dns_resolvconfip(char s[QUERY_MAXIPLEN],uint32 scope[QUERY_MAXNS])
+{
+  struct taia now;
+
+  taia_now(&now);
+  if (taia_less(&deadline,&now)) ok = 0;
+  if (!uses) ok = 0;
+
+  if (!ok) {
+    if (init(ip,scopes) < 0) return DNS_INT;
+    taia_uint(&deadline,600);
+    taia_add(&deadline,&now,&deadline);
+    uses = 10000;
+    ok = 1;
+  }
+
+  --uses;
+  byte_copy(s,QUERY_MAXIPLEN,ip);
+  byte_copy(scope,128,scopes);
+  return 0;
+}
-- 
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