From: Jakub Hrozek Date: Tue, 25 Nov 2014 17:33:21 +0000 (+0100) Subject: rwrap: Recursively add additional data X-Git-Url: http://git.samba.org/samba.git/?p=obnox%2Fcwrap%2Fresolv_wrapper.git;a=commitdiff_plain;h=c3f3bfb7c91949f3ea5b41393d9afa9f168b82f4 rwrap: Recursively add additional data Change how we construct the fake answer such that the header and question are added first, then the answers and finally additional data. Signed-off-by: Jakub Hrozek Reviewed-by: Andreas Schneider Reviewed-by: Guenther Deschner --- diff --git a/src/resolv_wrapper.c b/src/resolv_wrapper.c index ea13aa6..69f4484 100644 --- a/src/resolv_wrapper.c +++ b/src/resolv_wrapper.c @@ -427,6 +427,7 @@ static ssize_t rwrap_fake_a(struct rwrap_fake_rr *rr, "Malformed record, no or wrong value!\n"); return -1; } + RWRAP_LOG(RWRAP_LOG_TRACE, "Adding A RR"); resp_size = rwrap_fake_rdata_common(ns_t_a, sizeof(struct in_addr), rr->key, anslen, &a); @@ -451,6 +452,7 @@ static ssize_t rwrap_fake_aaaa(struct rwrap_fake_rr *rr, "Malformed record, no or wrong value!\n"); return -1; } + RWRAP_LOG(RWRAP_LOG_TRACE, "Adding AAAA RR"); resp_size = rwrap_fake_rdata_common(ns_t_aaaa, sizeof(struct in6_addr), rr->key, anslen, &a); @@ -478,6 +480,7 @@ static ssize_t rwrap_fake_srv(struct rwrap_fake_rr *rr, "Malformed record, no or wrong value!\n"); return -1; } + RWRAP_LOG(RWRAP_LOG_TRACE, "Adding SRV RR"); rdata_size = 3 * sizeof(uint16_t); /* Prepare the data to write */ @@ -520,6 +523,7 @@ static ssize_t rwrap_fake_soa(struct rwrap_fake_rr *rr, "Malformed record, no or wrong value!\n"); return -1; } + RWRAP_LOG(RWRAP_LOG_TRACE, "Adding SOA RR"); rdata_size = 5 * sizeof(uint16_t); compressed_ns_len = ns_name_compress(rr->rrdata.soa_rec.nameserver, @@ -571,6 +575,7 @@ static ssize_t rwrap_fake_cname(struct rwrap_fake_rr *rr, "Malformed record, no or wrong value!\n"); return -1; } + RWRAP_LOG(RWRAP_LOG_TRACE, "Adding CNAME RR"); /* Prepare the data to write */ rdata_size = ns_name_compress(rr->rrdata.cname_rec, @@ -755,41 +760,78 @@ static ssize_t rwrap_fake_empty(int type, return resp_data; } -static ssize_t rwrap_fake_answer(struct rwrap_fake_rr *rrs, - uint8_t *answer, - size_t anslen) +static inline bool rwrap_known_type(int type) +{ + switch (type) { + case ns_t_a: + case ns_t_aaaa: + case ns_t_srv: + case ns_t_soa: + case ns_t_cname: + return true; + } + + return false; +} +static int rwrap_ancount(struct rwrap_fake_rr *rrs, int qtype) { - ssize_t resp_data; - size_t remaining = anslen; + int i; + int ancount = 0; - resp_data = rwrap_fake_header(&answer, remaining, 1, 0); - if (resp_data < 0) { - return -1; + /* Include all RRs in the stack until the sought type + * in the answer section. This is the case i.e. when looking + * up an A record but the name points to a CNAME + */ + for (i = 0; i < RWRAP_MAX_RECURSION; i++) { + ancount++; + + if (rwrap_known_type(rrs[i].type) && + rrs[i].type == qtype) { + break; + } } - remaining -= resp_data; - resp_data += rwrap_fake_question(rrs->key, rrs->type, &answer, remaining); - if (resp_data < 0) { - return -1; + /* Return 0 records if the sought type wasn't in the stack */ + return i < RWRAP_MAX_RECURSION ? ancount : 0; +} + +static int rwrap_arcount(struct rwrap_fake_rr *rrs, int ancount) +{ + int i; + int arcount = 0; + + /* start from index ancount */ + for (i = ancount; i < RWRAP_MAX_RECURSION; i++) { + if (rwrap_known_type(rrs[i].type)) { + arcount++; + } } - remaining -= resp_data; - switch (rrs->type) { + return arcount; +} + +static ssize_t rwrap_add_rr(struct rwrap_fake_rr *rr, + uint8_t *answer, + size_t anslen) +{ + ssize_t resp_data; + + switch (rr->type) { case ns_t_a: - resp_data += rwrap_fake_a(rrs, answer, anslen); + resp_data = rwrap_fake_a(rr, answer, anslen); break; case ns_t_aaaa: - resp_data += rwrap_fake_aaaa(rrs, answer, anslen); + resp_data = rwrap_fake_aaaa(rr, answer, anslen); break; case ns_t_srv: - resp_data += rwrap_fake_srv(rrs, answer, anslen); + resp_data = rwrap_fake_srv(rr, answer, anslen); break; case ns_t_soa: - resp_data += rwrap_fake_soa(rrs, answer, anslen); + resp_data = rwrap_fake_soa(rr, answer, anslen); break; case ns_t_cname: - resp_data += rwrap_fake_cname(rrs, answer, anslen); + resp_data = rwrap_fake_cname(rr, answer, anslen); break; default: return -1; @@ -798,6 +840,63 @@ static ssize_t rwrap_fake_answer(struct rwrap_fake_rr *rrs, return resp_data; } +static ssize_t rwrap_fake_answer(struct rwrap_fake_rr *rrs, + int type, + uint8_t *answer, + size_t anslen) + +{ + ssize_t resp_data; + ssize_t rrlen; + size_t remaining = anslen; + int ancount; + int arcount; + int i; + + ancount = rwrap_ancount(rrs, type); + arcount = rwrap_arcount(rrs, ancount); + RWRAP_LOG(RWRAP_LOG_TRACE, + "Got %d answers and %d additional records\n", ancount, arcount); + + resp_data = rwrap_fake_header(&answer, remaining, ancount, arcount); + if (resp_data < 0) { + return -1; + } + remaining -= resp_data; + + resp_data += rwrap_fake_question(rrs->key, rrs->type, &answer, remaining); + if (resp_data < 0) { + return -1; + } + remaining -= resp_data; + + /* answer */ + for (i = 0; i < ancount; i++) { + rrlen = rwrap_add_rr(&rrs[i], answer, remaining); + if (rrlen < 0) { + return -1; + } + remaining -= rrlen; + answer += rrlen; + resp_data += rrlen; + } + + /* add authoritative NS here? */ + + /* additional records */ + for (i = ancount; i < ancount + arcount; i++) { + rrlen = rwrap_add_rr(&rrs[i], answer, remaining); + if (rrlen < 0) { + return -1; + } + remaining -= rrlen; + answer += rrlen; + resp_data += rrlen; + } + + return resp_data; +} + /* Reads in a file in the following format: * TYPE RDATA * @@ -835,7 +934,7 @@ static int rwrap_res_fake_hosts(const char *hostfile, case 0: RWRAP_LOG(RWRAP_LOG_TRACE, "Found record for [%s]\n", query_name); - resp_size = rwrap_fake_answer(rrs, answer, anslen); + resp_size = rwrap_fake_answer(rrs, type, answer, anslen); break; case ENOENT: RWRAP_LOG(RWRAP_LOG_TRACE,