diff options
author | Jannis Hoffmann <jannis@fehcom.de> | 2024-07-09 13:58:20 +0200 |
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committer | Jannis Hoffmann <jannis@fehcom.de> | 2024-07-09 13:58:20 +0200 |
commit | 249866e3d1e11dc72eaa1305f4bb479ded92ef38 (patch) | |
tree | 7118c5f58e29fe61c100e4d067bb90ba8d52589e /src/dnsstub/dns_rcrw.c | |
parent | 96cf8dffe4f7b0b910f790066ae622dc429eb522 (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.c | 141 |
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; +} |