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authorJannis Hoffmann <jannis@fehcom.de>2024-07-09 13:58:20 +0200
committerJannis Hoffmann <jannis@fehcom.de>2024-07-09 13:58:20 +0200
commit249866e3d1e11dc72eaa1305f4bb479ded92ef38 (patch)
tree7118c5f58e29fe61c100e4d067bb90ba8d52589e /src/dnsstub/dns_rcip.c
parent96cf8dffe4f7b0b910f790066ae622dc429eb522 (diff)
reorganized file structure
Moved c files into src/. Corrected VERSION file. Removed BUILD and FILES.
Diffstat (limited to 'src/dnsstub/dns_rcip.c')
-rw-r--r--src/dnsstub/dns_rcip.c114
1 files changed, 114 insertions, 0 deletions
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;
+}