diff options
Diffstat (limited to 'src/dnsstub/dns_ip.c')
| -rw-r--r-- | src/dnsstub/dns_ip.c | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/src/dnsstub/dns_ip.c b/src/dnsstub/dns_ip.c new file mode 100644 index 0000000..74bc24f --- /dev/null +++ b/src/dnsstub/dns_ip.c @@ -0,0 +1,198 @@ +#include "stralloc.h" +#include "uint_t.h" +#include "byte.h" +#include "ip.h" +#include "dnsresolv.h" + +/** + * @file dns_ip.c + * @authors djb, fefe, feh + * @ref ucspi-tcp6 + * @brief DNS IP query + */ + +static char *q = 0; + +int dns_ip4_packet(stralloc *out,const char *buf,unsigned int len) +{ + unsigned int pos; + char header[12]; + uint16 numanswers; + uint16 datalen; + int ranswers = 0; + + if (!stralloc_copys(out,"")) return DNS_MEM; + + pos = dns_packet_copy(buf,len,0,header,12); if (!pos) return DNS_ERR; + uint16_unpack_big(header + 6,&numanswers); + pos = dns_packet_skipname(buf,len,pos); if (!pos) return DNS_ERR; + pos += 4; + + while (numanswers--) { + pos = dns_packet_skipname(buf,len,pos); if (!pos) return DNS_ERR; + pos = dns_packet_copy(buf,len,pos,header,10); if (!pos) return DNS_ERR; + uint16_unpack_big(header + 8,&datalen); + if (byte_equal(header,2,DNS_T_A)) + if (byte_equal(header + 2,2,DNS_C_IN)) + if (datalen == 4) { + if (!dns_packet_copy(buf,len,pos,header,4)) return DNS_ERR; + if (!stralloc_catb(out,header,4)) return DNS_MEM; + } + pos += datalen; + ++ranswers; + } + + dns_sortip4(out->s,out->len); + return ranswers; +} + +int dns_ip4(stralloc *out,stralloc *fqdn) +{ + unsigned int i; + char code = 0; + int dot = 0; + char ch; + char ip[4]; + int r; + int rc = 0; + + if (!stralloc_copys(out,"")) return DNS_MEM; + if (!stralloc_readyplus(fqdn,1)) return DNS_MEM; + + fqdn->s[fqdn->len] = 0; /* test FQDN string */ + for (i = 1; i < fqdn->len; i++) { + if (fqdn->s[i] >= '_') { code = 127; break; } + if (fqdn->s[i] == '.') dot++; + } + + if (code != 127 && dot == 3) /* if FQDN is just IPv4 */ + if (ip4_scan(fqdn->s,ip) || ip4_scanbracket(fqdn->s,ip)) { + if (!stralloc_copyb(out,ip,4)) return DNS_MEM; + return 1; + } + + code = 0; + for (i = 0; i <= fqdn->len; ++i) { + if (i < fqdn->len) + ch = fqdn->s[i]; + else + ch = '.'; + + if ((ch == '[') || (ch == ']')) continue; + if (ch == '.') { + if (!stralloc_append(out,&code)) return DNS_MEM; + code = 0; + continue; + } + if ((ch >= '0') && (ch <= '9')) { + code *= 10; + code += ch - '0'; + continue; + } + + if (dns_domain_fromdot(&q,fqdn->s,fqdn->len) <= 0) return DNS_ERR; // fdqn -> A query -> response + if (dns_resolve(q,DNS_T_A) >= 0) { + if ((r = dns_ip4_packet(out,dns_resolve_tx.packet,dns_resolve_tx.packetlen)) < 0) return DNS_ERR; + dns_transmit_free(&dns_resolve_tx); + dns_domain_free(&q); + rc += r; + } + + return rc; + } + + out->len &= ~3; + return 0; +} + +int dns_ip6_packet(stralloc *out,const char *buf,unsigned int len) +{ + unsigned int pos; + char header[16]; + uint16 numanswers; + uint16 datalen; + int ranswers = 0; + + if (!stralloc_copys(out,"")) return DNS_MEM; + + pos = dns_packet_copy(buf,len,0,header,12); if (!pos) return DNS_ERR; + uint16_unpack_big(header + 6,&numanswers); + pos = dns_packet_skipname(buf,len,pos); if (!pos) return DNS_ERR; + pos += 4; + + while (numanswers--) { + pos = dns_packet_skipname(buf,len,pos); if (!pos) return DNS_ERR; + pos = dns_packet_copy(buf,len,pos,header,10); if (!pos) return DNS_ERR; + uint16_unpack_big(header + 8,&datalen); + if (byte_equal(header,2,DNS_T_AAAA)) { + if (byte_equal(header + 2,2,DNS_C_IN)) + if (datalen == 16) { + if (!dns_packet_copy(buf,len,pos,header,16)) return DNS_ERR; + if (!stralloc_catb(out,header,16)) return DNS_MEM; + } + } else if (byte_equal(header,2,DNS_T_A)) + if (byte_equal(header + 2,2,DNS_C_IN)) + if (datalen == 4) { + byte_copy(header,12,V4mappedprefix); + if (!dns_packet_copy(buf,len,pos,header + 12,4)) return DNS_ERR; + if (!stralloc_catb(out,header,16)) return DNS_MEM; + } + pos += datalen; + ++ranswers; + } + + dns_sortip6(out->s,out->len); + return ranswers; +} + +int dns_ip6(stralloc *out,stralloc *fqdn) +{ + unsigned int i; + char code; + char ch; + char ip[16]; + int r; + int rc = 0; + + if (!stralloc_copys(out,"")) return DNS_MEM; + if (!stralloc_readyplus(fqdn,1)) return DNS_MEM; + + fqdn->s[fqdn->len] = 0; /* if FQDN is just IPv6 */ + if (ip6_scan(fqdn->s,ip) || ip6_scanbracket(fqdn->s,ip)) { + if (!stralloc_copyb(out,ip,16)) return DNS_MEM; + return 1; + } + + code = 0; + for (i = 0; i <= fqdn->len; ++i) { + if (i < fqdn->len) + ch = fqdn->s[i]; + else + ch = '.'; + + if ((ch == '[') || (ch == ']')) continue; + if (ch == '.') { + if (!stralloc_append(out,&code)) return DNS_MEM; + code = 0; + continue; + } + if ((ch >= '0') && (ch <= '9')) { + code *= 10; + code += ch - '0'; + continue; + } + + if (dns_domain_fromdot(&q,fqdn->s,fqdn->len) <= 0) return DNS_ERR; // fqdn -> AAAA query -> response + if (dns_resolve(q,DNS_T_AAAA) >= 0) { + if ((r = dns_ip6_packet(out,dns_resolve_tx.packet,dns_resolve_tx.packetlen)) < 0) return DNS_ERR; + dns_transmit_free(&dns_resolve_tx); + dns_domain_free(&q); + rc += r; + } + + return rc; + } + + out->len &= ~3; + return 0; +} |