diff options
Diffstat (limited to 'lib/addns/dnsmarshall.c')
| -rw-r--r-- | lib/addns/dnsmarshall.c | 532 |
1 files changed, 532 insertions, 0 deletions
diff --git a/lib/addns/dnsmarshall.c b/lib/addns/dnsmarshall.c new file mode 100644 index 0000000..a07ed78 --- /dev/null +++ b/lib/addns/dnsmarshall.c @@ -0,0 +1,532 @@ +/* + Linux DNS client library implementation + Copyright (C) 2006 Gerald Carter <jerry@samba.org> + + ** NOTE! The following LGPL license applies to the libaddns + ** library. This does NOT imply that all of Samba is released + ** under the LGPL + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, see <http://www.gnu.org/licenses/>. +*/ + +#include "dns.h" +#include "assert.h" + +struct dns_buffer *dns_create_buffer(TALLOC_CTX *mem_ctx) +{ + struct dns_buffer *result; + + if (!(result = talloc_zero(mem_ctx, struct dns_buffer))) { + return NULL; + } + + result->offset = 0; + result->error = ERROR_DNS_SUCCESS; + + /* + * Small initial size to exercise the realloc code + */ + result->size = 2; + + if (!(result->data = talloc_zero_array(result, uint8_t, result->size))) { + TALLOC_FREE(result); + return NULL; + } + + return result; +} + +void dns_marshall_buffer(struct dns_buffer *buf, const uint8_t *data, + size_t len) +{ + if (!ERR_DNS_IS_OK(buf->error)) return; + + if (buf->offset + len < buf->offset) { + /* + * Wraparound! + */ + buf->error = ERROR_DNS_INVALID_PARAMETER; + return; + } + + if ((buf->offset + len) > 0xffff) { + /* + * Only 64k possible + */ + buf->error = ERROR_DNS_INVALID_PARAMETER; + return; + } + + if (buf->offset + len > buf->size) { + size_t new_size = buf->offset + len; + uint8_t *new_data; + + /* + * Don't do too many reallocs, round up to some multiple + */ + + new_size += (64 - (new_size % 64)); + + if (!(new_data = talloc_realloc(buf, buf->data, uint8_t, + new_size))) { + buf->error = ERROR_DNS_NO_MEMORY; + return; + } + + buf->size = new_size; + buf->data = new_data; + } + + memcpy(buf->data + buf->offset, data, len); + buf->offset += len; + return; +} + +void dns_marshall_uint16(struct dns_buffer *buf, uint16_t val) +{ + uint16_t n_val = htons(val); + dns_marshall_buffer(buf, (uint8_t *)&n_val, sizeof(n_val)); +} + +void dns_marshall_uint32(struct dns_buffer *buf, uint32_t val) +{ + uint32_t n_val = htonl(val); + dns_marshall_buffer(buf, (uint8_t *)&n_val, sizeof(n_val)); +} + +void dns_unmarshall_buffer(struct dns_buffer *buf, uint8_t *data, + size_t len) +{ + if (!(ERR_DNS_IS_OK(buf->error))) return; + + if ((len > buf->size) || (buf->offset + len > buf->size)) { + buf->error = ERROR_DNS_INVALID_MESSAGE; + return; + } + + memcpy((void *)data, (const void *)(buf->data + buf->offset), len); + buf->offset += len; + + return; +} + +void dns_unmarshall_uint16(struct dns_buffer *buf, uint16_t *val) +{ + uint16_t n_val; + + dns_unmarshall_buffer(buf, (uint8_t *)&n_val, sizeof(n_val)); + if (!(ERR_DNS_IS_OK(buf->error))) return; + + *val = ntohs(n_val); +} + +void dns_unmarshall_uint32(struct dns_buffer *buf, uint32_t *val) +{ + uint32_t n_val; + + dns_unmarshall_buffer(buf, (uint8_t *)&n_val, sizeof(n_val)); + if (!(ERR_DNS_IS_OK(buf->error))) return; + + *val = ntohl(n_val); +} + +void dns_marshall_domain_name(struct dns_buffer *buf, + const struct dns_domain_name *name) +{ + struct dns_domain_label *label; + char end_char = '\0'; + + /* + * TODO: Implement DNS compression + */ + + for (label = name->pLabelList; label != NULL; label = label->next) { + uint8_t len = label->len; + + dns_marshall_buffer(buf, (uint8_t *)&len, sizeof(len)); + if (!ERR_DNS_IS_OK(buf->error)) return; + + dns_marshall_buffer(buf, (uint8_t *)label->label, len); + if (!ERR_DNS_IS_OK(buf->error)) return; + } + + dns_marshall_buffer(buf, (uint8_t *)&end_char, 1); +} + +static void dns_unmarshall_label(TALLOC_CTX *mem_ctx, + int level, + struct dns_buffer *buf, + struct dns_domain_label **plabel) +{ + struct dns_domain_label *label; + uint8_t len; + + if (!ERR_DNS_IS_OK(buf->error)) return; + + if (level > 128) { + /* + * Protect against recursion + */ + buf->error = ERROR_DNS_INVALID_MESSAGE; + return; + } + + dns_unmarshall_buffer(buf, &len, sizeof(len)); + if (!ERR_DNS_IS_OK(buf->error)) return; + + if (len == 0) { + *plabel = NULL; + return; + } + + if ((len & 0xc0) == 0xc0) { + /* + * We've got a compressed name. Build up a new "fake" buffer + * and using the calculated offset. + */ + struct dns_buffer new_buf; + uint8_t low; + + dns_unmarshall_buffer(buf, &low, sizeof(low)); + if (!ERR_DNS_IS_OK(buf->error)) return; + + new_buf = *buf; + new_buf.offset = len & 0x3f; + new_buf.offset <<= 8; + new_buf.offset |= low; + + dns_unmarshall_label(mem_ctx, level+1, &new_buf, plabel); + buf->error = new_buf.error; + return; + } + + if ((len & 0xc0) != 0) { + buf->error = ERROR_DNS_INVALID_NAME; + return; + } + + if (!(label = talloc_zero(mem_ctx, struct dns_domain_label))) { + buf->error = ERROR_DNS_NO_MEMORY; + return; + } + + label->len = len; + + if (!(label->label = talloc_zero_array(label, char, len+1))) { + buf->error = ERROR_DNS_NO_MEMORY; + goto error; + } + + dns_unmarshall_buffer(buf, (uint8_t *)label->label, len); + if (!ERR_DNS_IS_OK(buf->error)) goto error; + + dns_unmarshall_label(label, level+1, buf, &label->next); + if (!ERR_DNS_IS_OK(buf->error)) goto error; + + *plabel = label; + return; + + error: + TALLOC_FREE(label); + return; +} + +void dns_unmarshall_domain_name(TALLOC_CTX *mem_ctx, + struct dns_buffer *buf, + struct dns_domain_name **pname) +{ + struct dns_domain_name *name; + + if (!ERR_DNS_IS_OK(buf->error)) return; + + if (!(name = talloc_zero(mem_ctx, struct dns_domain_name))) { + buf->error = ERROR_DNS_NO_MEMORY; + return; + } + + dns_unmarshall_label(name, 0, buf, &name->pLabelList); + + if (!ERR_DNS_IS_OK(buf->error)) { + return; + } + + *pname = name; + return; +} + +static void dns_marshall_question(struct dns_buffer *buf, + const struct dns_question *q) +{ + dns_marshall_domain_name(buf, q->name); + dns_marshall_uint16(buf, q->q_type); + dns_marshall_uint16(buf, q->q_class); +} + +static void dns_unmarshall_question(TALLOC_CTX *mem_ctx, + struct dns_buffer *buf, + struct dns_question **pq) +{ + struct dns_question *q; + + if (!(ERR_DNS_IS_OK(buf->error))) return; + + if (!(q = talloc_zero(mem_ctx, struct dns_question))) { + buf->error = ERROR_DNS_NO_MEMORY; + return; + } + + dns_unmarshall_domain_name(q, buf, &q->name); + dns_unmarshall_uint16(buf, &q->q_type); + dns_unmarshall_uint16(buf, &q->q_class); + + if (!(ERR_DNS_IS_OK(buf->error))) return; + + *pq = q; +} + +static void dns_marshall_rr(struct dns_buffer *buf, + const struct dns_rrec *r) +{ + dns_marshall_domain_name(buf, r->name); + dns_marshall_uint16(buf, r->type); + dns_marshall_uint16(buf, r->r_class); + dns_marshall_uint32(buf, r->ttl); + dns_marshall_uint16(buf, r->data_length); + dns_marshall_buffer(buf, r->data, r->data_length); +} + +static void dns_unmarshall_rr(TALLOC_CTX *mem_ctx, + struct dns_buffer *buf, + struct dns_rrec **pr) +{ + struct dns_rrec *r; + + if (!(ERR_DNS_IS_OK(buf->error))) return; + + if (!(r = talloc_zero(mem_ctx, struct dns_rrec))) { + buf->error = ERROR_DNS_NO_MEMORY; + return; + } + + dns_unmarshall_domain_name(r, buf, &r->name); + dns_unmarshall_uint16(buf, &r->type); + dns_unmarshall_uint16(buf, &r->r_class); + dns_unmarshall_uint32(buf, &r->ttl); + dns_unmarshall_uint16(buf, &r->data_length); + r->data = NULL; + + if (!(ERR_DNS_IS_OK(buf->error))) return; + + if (r->data_length != 0) { + if (!(r->data = talloc_zero_array(r, uint8_t, r->data_length))) { + buf->error = ERROR_DNS_NO_MEMORY; + return; + } + dns_unmarshall_buffer(buf, r->data, r->data_length); + } + + if (!(ERR_DNS_IS_OK(buf->error))) return; + + *pr = r; +} + +DNS_ERROR dns_marshall_request(TALLOC_CTX *mem_ctx, + const struct dns_request *req, + struct dns_buffer **pbuf) +{ + struct dns_buffer *buf; + uint16_t i; + + if (!(buf = dns_create_buffer(mem_ctx))) { + return ERROR_DNS_NO_MEMORY; + } + + dns_marshall_uint16(buf, req->id); + dns_marshall_uint16(buf, req->flags); + dns_marshall_uint16(buf, req->num_questions); + dns_marshall_uint16(buf, req->num_answers); + dns_marshall_uint16(buf, req->num_auths); + dns_marshall_uint16(buf, req->num_additionals); + + for (i=0; i<req->num_questions; i++) { + dns_marshall_question(buf, req->questions[i]); + } + for (i=0; i<req->num_answers; i++) { + dns_marshall_rr(buf, req->answers[i]); + } + for (i=0; i<req->num_auths; i++) { + dns_marshall_rr(buf, req->auths[i]); + } + for (i=0; i<req->num_additionals; i++) { + dns_marshall_rr(buf, req->additionals[i]); + } + + if (!ERR_DNS_IS_OK(buf->error)) { + DNS_ERROR err = buf->error; + TALLOC_FREE(buf); + return err; + } + + *pbuf = buf; + return ERROR_DNS_SUCCESS; +} + +DNS_ERROR dns_unmarshall_request(TALLOC_CTX *mem_ctx, + struct dns_buffer *buf, + struct dns_request **preq) +{ + struct dns_request *req; + uint16_t i; + DNS_ERROR err = ERROR_DNS_NO_MEMORY; + + if (!(req = talloc_zero(mem_ctx, struct dns_request))) { + return err; + } + + dns_unmarshall_uint16(buf, &req->id); + dns_unmarshall_uint16(buf, &req->flags); + dns_unmarshall_uint16(buf, &req->num_questions); + dns_unmarshall_uint16(buf, &req->num_answers); + dns_unmarshall_uint16(buf, &req->num_auths); + dns_unmarshall_uint16(buf, &req->num_additionals); + + if (!ERR_DNS_IS_OK(buf->error)){ + err = buf->error; + goto error; + } + + err = ERROR_DNS_NO_MEMORY; + + if ((req->num_questions != 0) && + !(req->questions = talloc_zero_array(req, struct dns_question *, + req->num_questions))) { + goto error; + } + if ((req->num_answers != 0) && + !(req->answers = talloc_zero_array(req, struct dns_rrec *, + req->num_answers))) { + goto error; + } + if ((req->num_auths != 0) && + !(req->auths = talloc_zero_array(req, struct dns_rrec *, + req->num_auths))) { + goto error; + } + if ((req->num_additionals != 0) && + !(req->additionals = talloc_zero_array(req, struct dns_rrec *, + req->num_additionals))) { + goto error; + } + + for (i=0; i<req->num_questions; i++) { + dns_unmarshall_question(req->questions, buf, + &req->questions[i]); + } + for (i=0; i<req->num_answers; i++) { + dns_unmarshall_rr(req->answers, buf, + &req->answers[i]); + } + for (i=0; i<req->num_auths; i++) { + dns_unmarshall_rr(req->auths, buf, + &req->auths[i]); + } + for (i=0; i<req->num_additionals; i++) { + dns_unmarshall_rr(req->additionals, buf, + &req->additionals[i]); + } + + if (!ERR_DNS_IS_OK(buf->error)) { + err = buf->error; + goto error; + } + + *preq = req; + return ERROR_DNS_SUCCESS; + + error: + TALLOC_FREE(req); + return err; +} + +struct dns_request *dns_update2request(struct dns_update_request *update) +{ + struct dns_request *req; + + /* + * This is a non-specified construct that happens to work on Linux/gcc + * and I would expect it to work everywhere else. dns_request and + * dns_update_request are essentially the same structures with + * different names, so any difference would mean that the compiler + * applied two different variations of padding given the same types in + * the structures. + */ + + req = (struct dns_request *)(void *)update; + + /* + * The assert statement here looks like we could do the equivalent + * assignments to get portable, but it would mean that we have to + * allocate the dns_question record for the dns_zone records. We + * assume that if this assert works then the same holds true for + * dns_zone<>dns_question as well. + */ + +#ifdef DEVELOPER + assert((req->id == update->id) && (req->flags == update->flags) && + (req->num_questions == update->num_zones) && + (req->num_answers == update->num_preqs) && + (req->num_auths == update->num_updates) && + (req->num_additionals == update->num_additionals) && + (req->questions == + (struct dns_question **)(void *)update->zones) && + (req->answers == update->preqs) && + (req->auths == update->updates) && + (req->additionals == update->additionals)); +#endif + + return req; +} + +struct dns_update_request *dns_request2update(struct dns_request *request) +{ + /* + * For portability concerns see dns_update2request; + */ + return (struct dns_update_request *)(void *)request; +} + +DNS_ERROR dns_marshall_update_request(TALLOC_CTX *mem_ctx, + struct dns_update_request *update, + struct dns_buffer **pbuf) +{ + return dns_marshall_request(mem_ctx, dns_update2request(update), pbuf); +} + +DNS_ERROR dns_unmarshall_update_request(TALLOC_CTX *mem_ctx, + struct dns_buffer *buf, + struct dns_update_request **pupreq) +{ + /* + * See comments above about portability. If the above works, this will + * as well. + */ + + return dns_unmarshall_request(mem_ctx, buf, + (struct dns_request **)(void *)pupreq); +} + +uint16_t dns_response_code(uint16_t flags) +{ + return flags & 0xF; +} |