busybox/networking/udhcp/packet.c

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/* vi: set sw=4 ts=4: */
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/*
* Packet ops
*
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* Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
*
* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
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#include "common.h"
#include "dhcpd.h"
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <netpacket/packet.h>
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#if ENABLE_UDHCPC || ENABLE_UDHCPD
void FAST_FUNC udhcp_init_header(struct dhcp_packet *packet, char type)
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{
memset(packet, 0, sizeof(*packet));
packet->op = BOOTREQUEST; /* if client to a server */
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switch (type) {
case DHCPOFFER:
case DHCPACK:
case DHCPNAK:
packet->op = BOOTREPLY; /* if server to client */
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}
packet->htype = 1; /* ethernet */
packet->hlen = 6;
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packet->cookie = htonl(DHCP_MAGIC);
if (DHCP_END != 0)
packet->options[0] = DHCP_END;
udhcp_add_simple_option(packet, DHCP_MESSAGE_TYPE, type);
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}
#endif
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#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 2
void FAST_FUNC udhcp_dump_packet(struct dhcp_packet *packet)
{
char buf[sizeof(packet->chaddr)*2 + 1];
if (dhcp_verbose < 2)
return;
Optionally re-introduce bb_info_msg() Between Busybox 1.24.2 and 1.25.0 the bb_info_msg() function was eliminated and calls to it changed to be bb_error_msg(). The downside of this is that daemons now log all messages to syslog at the LOG_ERR level which makes it hard to filter errors from informational messages. This change optionally re-introduces bb_info_msg(), controlled by a new option FEATURE_SYSLOG_INFO, restores all the calls to bb_info_msg() that were removed (only in applets that set logmode to LOGMODE_SYSLOG or LOGMODE_BOTH), and also changes informational messages in ifplugd and ntpd. The code size change of this is as follows (using 'defconfig' on x86_64 with gcc 7.3.0-27ubuntu1~18.04) function old new delta bb_info_msg - 182 +182 bb_vinfo_msg - 27 +27 static.log7 194 198 +4 log8 190 191 +1 log5 190 191 +1 crondlog 45 - -45 ------------------------------------------------------------------------------ (add/remove: 2/1 grow/shrink: 3/0 up/down: 215/-45) Total: 170 bytes If you don't care about everything being logged at LOG_ERR level then when FEATURE_SYSLOG_INFO is disabled Busybox actually gets smaller: function old new delta static.log7 194 200 +6 log8 190 193 +3 log5 190 193 +3 syslog_level 1 - -1 bb_verror_msg 583 581 -2 crondlog 45 - -45 ------------------------------------------------------------------------------ (add/remove: 0/2 grow/shrink: 3/1 up/down: 12/-48) Total: -36 bytes Signed-off-by: James Byrne <james.byrne@origamienergy.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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bb_info_msg(
//" op %x"
//" htype %x"
" hlen %x"
//" hops %x"
" xid %x"
//" secs %x"
//" flags %x"
" ciaddr %x"
" yiaddr %x"
" siaddr %x"
" giaddr %x"
//" sname %s"
//" file %s"
//" cookie %x"
//" options %s"
//, packet->op
//, packet->htype
, packet->hlen
//, packet->hops
, packet->xid
//, packet->secs
//, packet->flags
, packet->ciaddr
, packet->yiaddr
, packet->siaddr_nip
, packet->gateway_nip
//, packet->sname[64]
//, packet->file[128]
//, packet->cookie
//, packet->options[]
);
*bin2hex(buf, (void *) packet->chaddr, sizeof(packet->chaddr)) = '\0';
Optionally re-introduce bb_info_msg() Between Busybox 1.24.2 and 1.25.0 the bb_info_msg() function was eliminated and calls to it changed to be bb_error_msg(). The downside of this is that daemons now log all messages to syslog at the LOG_ERR level which makes it hard to filter errors from informational messages. This change optionally re-introduces bb_info_msg(), controlled by a new option FEATURE_SYSLOG_INFO, restores all the calls to bb_info_msg() that were removed (only in applets that set logmode to LOGMODE_SYSLOG or LOGMODE_BOTH), and also changes informational messages in ifplugd and ntpd. The code size change of this is as follows (using 'defconfig' on x86_64 with gcc 7.3.0-27ubuntu1~18.04) function old new delta bb_info_msg - 182 +182 bb_vinfo_msg - 27 +27 static.log7 194 198 +4 log8 190 191 +1 log5 190 191 +1 crondlog 45 - -45 ------------------------------------------------------------------------------ (add/remove: 2/1 grow/shrink: 3/0 up/down: 215/-45) Total: 170 bytes If you don't care about everything being logged at LOG_ERR level then when FEATURE_SYSLOG_INFO is disabled Busybox actually gets smaller: function old new delta static.log7 194 200 +6 log8 190 193 +3 log5 190 193 +3 syslog_level 1 - -1 bb_verror_msg 583 581 -2 crondlog 45 - -45 ------------------------------------------------------------------------------ (add/remove: 0/2 grow/shrink: 3/1 up/down: 12/-48) Total: -36 bytes Signed-off-by: James Byrne <james.byrne@origamienergy.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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bb_info_msg(" chaddr %s", buf);
}
#endif
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/* Read a packet from socket fd, return -1 on read error, -2 on packet error */
int FAST_FUNC udhcp_recv_kernel_packet(struct dhcp_packet *packet, int fd)
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{
int bytes;
memset(packet, 0, sizeof(*packet));
bytes = safe_read(fd, packet, sizeof(*packet));
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if (bytes < 0) {
libbb: reduce the overhead of single parameter bb_error_msg() calls Back in 2007, commit 0c97c9d43707 ("'simple' error message functions by Loic Grenie") introduced bb_simple_perror_msg() to allow for a lower overhead call to bb_perror_msg() when only a string was being printed with no parameters. This saves space for some CPU architectures because it avoids the overhead of a call to a variadic function. However there has never been a simple version of bb_error_msg(), and since 2007 many new calls to bb_perror_msg() have been added that only take a single parameter and so could have been using bb_simple_perror_message(). This changeset introduces 'simple' versions of bb_info_msg(), bb_error_msg(), bb_error_msg_and_die(), bb_herror_msg() and bb_herror_msg_and_die(), and replaces all calls that only take a single parameter, or use something like ("%s", arg), with calls to the corresponding 'simple' version. Since it is likely that single parameter calls to the variadic functions may be accidentally reintroduced in the future a new debugging config option WARN_SIMPLE_MSG has been introduced. This uses some macro magic which will cause any such calls to generate a warning, but this is turned off by default to avoid use of the unpleasant macros in normal circumstances. This is a large changeset due to the number of calls that have been replaced. The only files that contain changes other than simple substitution of function calls are libbb.h, libbb/herror_msg.c, libbb/verror_msg.c and libbb/xfuncs_printf.c. In miscutils/devfsd.c, networking/udhcp/common.h and util-linux/mdev.c additonal macros have been added for logging so that single parameter and multiple parameter logging variants exist. The amount of space saved varies considerably by architecture, and was found to be as follows (for 'defconfig' using GCC 7.4): Arm: -92 bytes MIPS: -52 bytes PPC: -1836 bytes x86_64: -938 bytes Note that for the MIPS architecture only an exception had to be made disabling the 'simple' calls for 'udhcp' (in networking/udhcp/common.h) because it made these files larger on MIPS. Signed-off-by: James Byrne <james.byrne@origamienergy.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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log1s("packet read error, ignoring");
return bytes; /* returns -1 */
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}
if (bytes < offsetof(struct dhcp_packet, options)
|| packet->cookie != htonl(DHCP_MAGIC)
) {
libbb: reduce the overhead of single parameter bb_error_msg() calls Back in 2007, commit 0c97c9d43707 ("'simple' error message functions by Loic Grenie") introduced bb_simple_perror_msg() to allow for a lower overhead call to bb_perror_msg() when only a string was being printed with no parameters. This saves space for some CPU architectures because it avoids the overhead of a call to a variadic function. However there has never been a simple version of bb_error_msg(), and since 2007 many new calls to bb_perror_msg() have been added that only take a single parameter and so could have been using bb_simple_perror_message(). This changeset introduces 'simple' versions of bb_info_msg(), bb_error_msg(), bb_error_msg_and_die(), bb_herror_msg() and bb_herror_msg_and_die(), and replaces all calls that only take a single parameter, or use something like ("%s", arg), with calls to the corresponding 'simple' version. Since it is likely that single parameter calls to the variadic functions may be accidentally reintroduced in the future a new debugging config option WARN_SIMPLE_MSG has been introduced. This uses some macro magic which will cause any such calls to generate a warning, but this is turned off by default to avoid use of the unpleasant macros in normal circumstances. This is a large changeset due to the number of calls that have been replaced. The only files that contain changes other than simple substitution of function calls are libbb.h, libbb/herror_msg.c, libbb/verror_msg.c and libbb/xfuncs_printf.c. In miscutils/devfsd.c, networking/udhcp/common.h and util-linux/mdev.c additonal macros have been added for logging so that single parameter and multiple parameter logging variants exist. The amount of space saved varies considerably by architecture, and was found to be as follows (for 'defconfig' using GCC 7.4): Arm: -92 bytes MIPS: -52 bytes PPC: -1836 bytes x86_64: -938 bytes Note that for the MIPS architecture only an exception had to be made disabling the 'simple' calls for 'udhcp' (in networking/udhcp/common.h) because it made these files larger on MIPS. Signed-off-by: James Byrne <james.byrne@origamienergy.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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bb_simple_info_msg("packet with bad magic, ignoring");
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return -2;
}
log2("received %s", "a packet");
/* log2 because more informative msg for valid packets is printed later at log1 level */
udhcp_dump_packet(packet);
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return bytes;
}
/* Construct a ip/udp header for a packet, send packet */
int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
uint32_t source_nip, int source_port,
uint32_t dest_nip, int dest_port, const uint8_t *dest_arp,
int ifindex)
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{
struct sockaddr_ll dest_sll;
struct ip_udp_dhcp_packet packet;
unsigned padding;
int fd;
int result = -1;
const char *msg;
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fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
if (fd < 0) {
msg = "socket(%s)";
goto ret_msg;
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}
memset(&dest_sll, 0, sizeof(dest_sll));
memset(&packet, 0, offsetof(struct ip_udp_dhcp_packet, data));
packet.data = *dhcp_pkt; /* struct copy */
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dest_sll.sll_family = AF_PACKET;
dest_sll.sll_protocol = htons(ETH_P_IP);
dest_sll.sll_ifindex = ifindex;
/*dest_sll.sll_hatype = ARPHRD_???;*/
/*dest_sll.sll_pkttype = PACKET_???;*/
dest_sll.sll_halen = 6;
memcpy(dest_sll.sll_addr, dest_arp, 6);
if (bind(fd, (struct sockaddr *)&dest_sll, sizeof(dest_sll)) < 0) {
msg = "bind(%s)";
goto ret_close;
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}
/* We were sending full-sized DHCP packets (zero padded),
* but some badly configured servers were seen dropping them.
* Apparently they drop all DHCP packets >576 *ethernet* octets big,
* whereas they may only drop packets >576 *IP* octets big
* (which for typical Ethernet II means 590 octets: 6+6+2 + 576).
*
* In order to work with those buggy servers,
* we truncate packets after end option byte.
*
* However, RFC 1542 says "The IP Total Length and UDP Length
* must be large enough to contain the minimal BOOTP header of 300 octets".
* Thus, we retain enough padding to not go below 300 BOOTP bytes.
* Some devices have filters which drop DHCP packets shorter than that.
*/
padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(packet.data.options);
if (padding > DHCP_SIZE - 300)
padding = DHCP_SIZE - 300;
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packet.ip.protocol = IPPROTO_UDP;
packet.ip.saddr = source_nip;
packet.ip.daddr = dest_nip;
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packet.udp.source = htons(source_port);
packet.udp.dest = htons(dest_port);
/* size, excluding IP header: */
packet.udp.len = htons(UDP_DHCP_SIZE - padding);
/* for UDP checksumming, ip.len is set to UDP packet len */
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packet.ip.tot_len = packet.udp.len;
packet.udp.check = inet_cksum(&packet,
IP_UDP_DHCP_SIZE - padding);
/* but for sending, it is set to IP packet len */
packet.ip.tot_len = htons(IP_UDP_DHCP_SIZE - padding);
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packet.ip.ihl = sizeof(packet.ip) >> 2;
packet.ip.version = IPVERSION;
packet.ip.ttl = IPDEFTTL;
packet.ip.check = inet_cksum(&packet.ip, sizeof(packet.ip));
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udhcp_dump_packet(dhcp_pkt);
result = sendto(fd, &packet, IP_UDP_DHCP_SIZE - padding, /*flags:*/ 0,
(struct sockaddr *) &dest_sll, sizeof(dest_sll));
msg = "sendto";
ret_close:
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close(fd);
if (result < 0) {
ret_msg:
bb_perror_msg(msg, "PACKET");
}
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return result;
}
/* Let the kernel do all the work for packet generation */
int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
uint32_t source_nip, int source_port,
uint32_t dest_nip, int dest_port,
const char *ifname)
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{
struct sockaddr_in sa;
unsigned padding;
int fd;
int result = -1;
const char *msg;
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fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (fd < 0) {
msg = "socket(%s)";
goto ret_msg;
}
setsockopt_reuseaddr(fd);
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/* If interface carrier goes down, unless we
* bind socket to a particular netdev, the packet
* can go out through another interface, eg. via
* default route despite being bound to a specific
* source IP. As such, bind to device hard and fail
* otherwise. Sending renewal packets on foreign
* interfaces makes no sense.
*/
if (ifname) {
if (setsockopt_bindtodevice(fd, ifname) < 0) {
msg = "bindtodevice";
goto ret_close;
}
}
memset(&sa, 0, sizeof(sa));
sa.sin_family = AF_INET;
sa.sin_port = htons(source_port);
sa.sin_addr.s_addr = source_nip;
if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
msg = "bind(%s)";
goto ret_close;
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}
memset(&sa, 0, sizeof(sa));
sa.sin_family = AF_INET;
sa.sin_port = htons(dest_port);
sa.sin_addr.s_addr = dest_nip;
if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
msg = "connect";
goto ret_close;
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}
udhcp_dump_packet(dhcp_pkt);
padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(dhcp_pkt->options);
if (padding > DHCP_SIZE - 300)
padding = DHCP_SIZE - 300;
result = safe_write(fd, dhcp_pkt, DHCP_SIZE - padding);
msg = "write";
ret_close:
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close(fd);
if (result < 0) {
ret_msg:
bb_perror_msg(msg, "UDP");
}
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return result;
}