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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_rcrw.c
parent96cf8dffe4f7b0b910f790066ae622dc429eb522 (diff)
reorganized file structure
Moved c files into src/. Corrected VERSION file. Removed BUILD and FILES.
Diffstat (limited to 'src/dnsstub/dns_rcrw.c')
-rw-r--r--src/dnsstub/dns_rcrw.c141
1 files changed, 141 insertions, 0 deletions
diff --git a/src/dnsstub/dns_rcrw.c b/src/dnsstub/dns_rcrw.c
new file mode 100644
index 0000000..4633fed
--- /dev/null
+++ b/src/dnsstub/dns_rcrw.c
@@ -0,0 +1,141 @@
+#include <unistd.h>
+#include "taia.h"
+#include "env.h"
+#include "byte.h"
+#include "str.h"
+#include "readclose.h"
+#include "dnsresolv.h"
+
+/**
+ @file dns_rcrw.c
+ @author djb
+ @source ucspi-tcp
+ @brief DNS receive rewrite
+*/
+
+static stralloc data = {0};
+
+static int init(stralloc *rules)
+{
+ char host[256];
+ const char *x;
+ int i;
+ int j;
+ int k;
+
+ if (!stralloc_copys(rules,"")) return DNS_MEM;
+
+ x = env_get("DNSREWRITEFILE");
+ if (!x) x = "/etc/dnsrewrite";
+
+ i = openreadclose(x,&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 (!stralloc_catb(rules,data.s + i,j - i)) return DNS_MEM;
+ while (rules->len) {
+ if (rules->s[rules->len - 1] != ' ')
+ if (rules->s[rules->len - 1] != '\t')
+ if (rules->s[rules->len - 1] != '\r')
+ break;
+ --rules->len;
+ }
+ if (!stralloc_0(rules)) return DNS_MEM;
+ i = j + 1;
+ }
+ return 0;
+ }
+
+ x = env_get("LOCALDOMAIN");
+ if (x) {
+ if (!stralloc_copys(&data,x)) return DNS_MEM;
+ if (!stralloc_append(&data," ")) return DNS_MEM;
+ if (!stralloc_copys(rules,"?:")) return DNS_MEM;
+ i = 0;
+ for (j = 0; j < data.len; ++j)
+ if (data.s[j] == ' ') {
+ if (!stralloc_cats(rules,"+.")) return DNS_MEM;
+ if (!stralloc_catb(rules,data.s + i,j - i)) return DNS_MEM;
+ i = j + 1;
+ }
+ if (!stralloc_0(rules)) return DNS_MEM;
+ if (!stralloc_cats(rules,"*.:")) return DNS_MEM;
+ if (!stralloc_0(rules)) return DNS_MEM;
+ return 0;
+ }
+
+ 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("search ",7,data.s + i) ||
+ byte_equal("search\t",7,data.s + i) ||
+ byte_equal("domain ",7,data.s + i) ||
+ byte_equal("domain\t",7,data.s + i)) {
+ if (!stralloc_copys(rules,"?:")) return DNS_MEM;
+ i += 7;
+ while (i < j) {
+ k = byte_chr(data.s + i,j - i,' ');
+ k = byte_chr(data.s + i,k,'\t');
+ if (!k) { ++i; continue; }
+ if (!stralloc_cats(rules,"+.")) return DNS_MEM;
+ if (!stralloc_catb(rules,data.s + i,k)) return DNS_MEM;
+ i += k;
+ }
+ if (!stralloc_0(rules)) return DNS_MEM;
+ if (!stralloc_cats(rules,"*.:")) return DNS_MEM;
+ if (!stralloc_0(rules)) return DNS_MEM;
+ return 0;
+ }
+ i = j + 1;
+ }
+ }
+
+ host[0] = 0;
+ if (gethostname(host,sizeof(host)) == -1) return DNS_ERR;
+ host[(sizeof(host)) - 1] = 0;
+ i = str_chr(host,'.');
+ if (host[i]) {
+ if (!stralloc_copys(rules,"?:")) return DNS_MEM;
+ if (!stralloc_cats(rules,host + i)) return DNS_MEM;
+ if (!stralloc_0(rules)) return DNS_MEM;
+ }
+ if (!stralloc_cats(rules,"*.:")) return DNS_MEM;
+ if (!stralloc_0(rules)) return DNS_MEM;
+
+ return 0;
+}
+
+static int ok = 0;
+static unsigned int uses;
+static struct taia deadline;
+static stralloc rules = {0}; /* defined if ok */
+
+int dns_resolvconfrewrite(stralloc *out)
+{
+ struct taia now;
+
+ taia_now(&now);
+ if (taia_less(&deadline,&now)) ok = 0;
+ if (!uses) ok = 0;
+
+ if (!ok) {
+ if (init(&rules) < 0) return DNS_INT;
+ taia_uint(&deadline,600);
+ taia_add(&deadline,&now,&deadline);
+ uses = 10000;
+ ok = 1;
+ }
+
+ --uses;
+ if (!stralloc_copy(out,&rules)) return DNS_MEM;
+ return 0;
+}