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sd-dhcp: parse error message in DECLINE or NAK

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If a client sends a DECLINE or a server sends a NAK, they can include
a string with a message to explain the error. Parse this and print it
at debug level.
This commit is contained in:
Tom Gundersen
2015-11-25 18:30:31 +01:00
parent cddf4d81ea
commit f693e9b38f
8 changed files with 84 additions and 74 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/libsystemd-network/dhcp-internal.h
+1 -2
View File
@@ -47,8 +47,7 @@ int dhcp_option_append(DHCPMessage *message, size_t size, size_t *offset, uint8_
typedef int (*dhcp_option_cb_t)(uint8_t code, uint8_t len,
const void *option, void *userdata);
int dhcp_option_parse(DHCPMessage *message, size_t len,
dhcp_option_cb_t cb, void *userdata);
int dhcp_option_parse(DHCPMessage *message, size_t len, dhcp_option_cb_t cb, void *userdata, char **error_message);
int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid,
uint8_t type, uint16_t arp_type, size_t optlen,
src/libsystemd-network/dhcp-option.c
+63 -46
View File
@@ -24,6 +24,9 @@
#include <stdio.h>
#include <string.h>
#include "alloc-util.h"
#include "utf8.h"
#include "dhcp-internal.h"
static int option_append(uint8_t options[], size_t size, size_t *offset,
@@ -139,72 +142,84 @@ int dhcp_option_append(DHCPMessage *message, size_t size, size_t *offset,
}
static int parse_options(const uint8_t options[], size_t buflen, uint8_t *overload,
uint8_t *message_type, dhcp_option_cb_t cb,
uint8_t *message_type, char **error_message, dhcp_option_cb_t cb,
void *userdata) {
uint8_t code, len;
const uint8_t *option;
size_t offset = 0;
while (offset < buflen) {
switch (options[offset]) {
case DHCP_OPTION_PAD:
offset++;
code = options[offset ++];
break;
switch (code) {
case DHCP_OPTION_PAD:
continue;
case DHCP_OPTION_END:
return 0;
}
if (buflen < offset + 1)
return -ENOBUFS;
len = options[offset ++];
if (buflen < offset + len)
return -EINVAL;
option = &options[offset];
switch (code) {
case DHCP_OPTION_MESSAGE_TYPE:
if (buflen < offset + 3)
return -ENOBUFS;
len = options[++offset];
if (len != 1)
return -EINVAL;
if (message_type)
*message_type = options[++offset];
else
offset++;
offset++;
*message_type = *option;
break;
case DHCP_OPTION_OVERLOAD:
if (buflen < offset + 3)
return -ENOBUFS;
case DHCP_OPTION_ERROR_MESSAGE:
if (len == 0)
return -EINVAL;
len = options[++offset];
if (error_message) {
_cleanup_free_ char *string = NULL;
/* Accept a trailing NUL byte */
if (memchr(option, 0, len - 1))
return -EINVAL;
string = strndup((const char *) option, len);
if (!string)
return -ENOMEM;
if (!ascii_is_valid(string))
return -EINVAL;
free(*error_message);
*error_message = string;
string = NULL;
}
break;
case DHCP_OPTION_OVERLOAD:
if (len != 1)
return -EINVAL;
if (overload)
*overload = options[++offset];
else
offset++;
offset++;
*overload = *option;
break;
default:
if (buflen < offset + 3)
return -ENOBUFS;
code = options[offset];
len = options[++offset];
if (buflen < ++offset + len)
return -EINVAL;
if (cb)
cb(code, len, &options[offset], userdata);
offset += len;
cb(code, len, option, userdata);
break;
}
offset += len;
}
if (offset < buflen)
@@ -213,8 +228,8 @@ static int parse_options(const uint8_t options[], size_t buflen, uint8_t *overlo
return 0;
}
int dhcp_option_parse(DHCPMessage *message, size_t len,
dhcp_option_cb_t cb, void *userdata) {
int dhcp_option_parse(DHCPMessage *message, size_t len, dhcp_option_cb_t cb, void *userdata, char **_error_message) {
_cleanup_free_ char *error_message = NULL;
uint8_t overload = 0;
uint8_t message_type = 0;
int r;
@@ -227,27 +242,29 @@ int dhcp_option_parse(DHCPMessage *message, size_t len,
len -= sizeof(DHCPMessage);
r = parse_options(message->options, len, &overload, &message_type,
cb, userdata);
r = parse_options(message->options, len, &overload, &message_type, &error_message, cb, userdata);
if (r < 0)
return r;
if (overload & DHCP_OVERLOAD_FILE) {
r = parse_options(message->file, sizeof(message->file),
NULL, &message_type, cb, userdata);
r = parse_options(message->file, sizeof(message->file), NULL, &message_type, &error_message, cb, userdata);
if (r < 0)
return r;
}
if (overload & DHCP_OVERLOAD_SNAME) {
r = parse_options(message->sname, sizeof(message->sname),
NULL, &message_type, cb, userdata);
r = parse_options(message->sname, sizeof(message->sname), NULL, &message_type, &error_message, cb, userdata);
if (r < 0)
return r;
}
if (message_type)
return message_type;
if (message_type == 0)
return -ENOMSG;
return -ENOMSG;
if (_error_message && IN_SET(message_type, DHCP_NAK, DHCP_DECLINE)) {
*_error_message = error_message;
error_message = NULL;
}
return message_type;
}
src/libsystemd-network/dhcp-protocol.h
+1
View File
@@ -132,6 +132,7 @@ enum {
DHCP_OPTION_MESSAGE_TYPE = 53,
DHCP_OPTION_SERVER_IDENTIFIER = 54,
DHCP_OPTION_PARAMETER_REQUEST_LIST = 55,
DHCP_OPTION_ERROR_MESSAGE = 56,
DHCP_OPTION_MAXIMUM_MESSAGE_SIZE = 57,
DHCP_OPTION_RENEWAL_T1_TIME = 58,
DHCP_OPTION_REBINDING_T2_TIME = 59,
src/libsystemd-network/sd-dhcp-client.c
+5 -4
View File
@@ -1082,7 +1082,7 @@ static int client_handle_offer(sd_dhcp_client *client, DHCPMessage *offer,
return r;
}
r = dhcp_option_parse(offer, len, dhcp_lease_parse_options, lease);
r = dhcp_option_parse(offer, len, dhcp_lease_parse_options, lease, NULL);
if (r != DHCP_OFFER) {
log_dhcp_client(client, "received message was not an OFFER, ignoring");
return -ENOMSG;
@@ -1121,7 +1121,7 @@ static int client_handle_forcerenew(sd_dhcp_client *client, DHCPMessage *force,
size_t len) {
int r;
r = dhcp_option_parse(force, len, NULL, NULL);
r = dhcp_option_parse(force, len, NULL, NULL, NULL);
if (r != DHCP_FORCERENEW)
return -ENOMSG;
@@ -1133,6 +1133,7 @@ static int client_handle_forcerenew(sd_dhcp_client *client, DHCPMessage *force,
static int client_handle_ack(sd_dhcp_client *client, DHCPMessage *ack,
size_t len) {
_cleanup_dhcp_lease_unref_ sd_dhcp_lease *lease = NULL;
_cleanup_free_ char *error_message = NULL;
int r;
r = dhcp_lease_new(&lease);
@@ -1147,9 +1148,9 @@ static int client_handle_ack(sd_dhcp_client *client, DHCPMessage *ack,
return r;
}
r = dhcp_option_parse(ack, len, dhcp_lease_parse_options, lease);
r = dhcp_option_parse(ack, len, dhcp_lease_parse_options, lease, &error_message);
if (r == DHCP_NAK) {
log_dhcp_client(client, "NAK");
log_dhcp_client(client, "NAK: %s", strna(error_message));
return -EADDRNOTAVAIL;
}
src/libsystemd-network/sd-dhcp-lease.c
+1 -1
View File
@@ -661,7 +661,7 @@ int dhcp_lease_parse_options(uint8_t code, uint8_t len, const void *option, void
break;
default:
log_debug("Ignoring option DHCP option %i while parsing.", code);
log_debug("Ignoring option DHCP option %"PRIu8" while parsing.", code);
break;
}
src/libsystemd-network/sd-dhcp-server.c
+3 -3
View File
@@ -699,6 +699,7 @@ static int get_pool_offset(sd_dhcp_server *server, be32_t requested_ip) {
int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message,
size_t length) {
_cleanup_dhcp_request_free_ DHCPRequest *req = NULL;
_cleanup_free_ char *error_message = NULL;
DHCPLease *existing_lease;
int type, r;
@@ -714,7 +715,7 @@ int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message,
if (!req)
return -ENOMEM;
type = dhcp_option_parse(message, length, parse_request, req);
type = dhcp_option_parse(message, length, parse_request, req, &error_message);
if (type < 0)
return 0;
@@ -784,8 +785,7 @@ int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message,
break;
}
case DHCP_DECLINE:
log_dhcp_server(server, "DECLINE (0x%x)",
be32toh(req->message->xid));
log_dhcp_server(server, "DECLINE (0x%x): %s", be32toh(req->message->xid), strna(error_message));
/* TODO: make sure we don't offer this address again */
src/libsystemd-network/test-dhcp-client.c
+3 -3
View File
@@ -223,7 +223,7 @@ int dhcp_network_send_udp_socket(int s, be32_t address, uint16_t port, const voi
static int test_discover_message_verify(size_t size, struct DHCPMessage *dhcp) {
int res;
res = dhcp_option_parse(dhcp, size, check_options, NULL);
res = dhcp_option_parse(dhcp, size, check_options, NULL, NULL);
assert_se(res == DHCP_DISCOVER);
if (verbose)
@@ -390,7 +390,7 @@ static int test_addr_acq_recv_request(size_t size, DHCPMessage *request) {
uint8_t *msg_bytes = (uint8_t *)request;
int res;
res = dhcp_option_parse(request, size, check_options, NULL);
res = dhcp_option_parse(request, size, check_options, NULL, NULL);
assert_se(res == DHCP_REQUEST);
assert_se(xid == request->xid);
@@ -420,7 +420,7 @@ static int test_addr_acq_recv_discover(size_t size, DHCPMessage *discover) {
uint8_t *msg_bytes = (uint8_t *)discover;
int res;
res = dhcp_option_parse(discover, size, check_options, NULL);
res = dhcp_option_parse(discover, size, check_options, NULL, NULL);
assert_se(res == DHCP_DISCOVER);
assert_se(msg_bytes[size - 1] == DHCP_OPTION_END);
src/libsystemd-network/test-dhcp-option.c
+7 -15
View File
@@ -75,9 +75,8 @@ static const char *dhcp_type(int type) {
static void test_invalid_buffer_length(void) {
DHCPMessage message;
assert_se(dhcp_option_parse(&message, 0, NULL, NULL) == -EINVAL);
assert_se(dhcp_option_parse(&message, sizeof(DHCPMessage) - 1, NULL, NULL)
== -EINVAL);
assert_se(dhcp_option_parse(&message, 0, NULL, NULL, NULL) == -EINVAL);
assert_se(dhcp_option_parse(&message, sizeof(DHCPMessage) - 1, NULL, NULL, NULL) == -EINVAL);
}
static void test_message_init(void) {
@@ -101,7 +100,7 @@ static void test_message_init(void) {
assert_se(magic[2] == 83);
assert_se(magic[3] == 99);
assert_se(dhcp_option_parse(message, len, NULL, NULL) >= 0);
assert_se(dhcp_option_parse(message, len, NULL, NULL, NULL) >= 0);
}
static DHCPMessage *create_message(uint8_t *options, uint16_t optlen,
@@ -264,19 +263,12 @@ static void test_options(struct option_desc *desc) {
buflen = sizeof(DHCPMessage) + optlen;
if (!desc) {
assert_se((res = dhcp_option_parse(message, buflen,
test_options_cb,
NULL)) == -ENOMSG);
assert_se((res = dhcp_option_parse(message, buflen, test_options_cb, NULL, NULL)) == -ENOMSG);
} else if (desc->success) {
assert_se((res = dhcp_option_parse(message, buflen,
test_options_cb,
desc)) >= 0);
assert_se(desc->pos == -1 && desc->filepos == -1 &&
desc->snamepos == -1);
assert_se((res = dhcp_option_parse(message, buflen, test_options_cb, desc, NULL)) >= 0);
assert_se(desc->pos == -1 && desc->filepos == -1 && desc->snamepos == -1);
} else
assert_se((res = dhcp_option_parse(message, buflen,
test_options_cb,
desc)) < 0);
assert_se((res = dhcp_option_parse(message, buflen, test_options_cb, desc, NULL)) < 0);
if (verbose)
printf("DHCP type %s\n", dhcp_type(res));