| /* dnsmasq is Copyright (c) 2000-2012 Simon Kelley |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; version 2 dated June, 1991, or |
| (at your option) version 3 dated 29 June, 2007. |
| |
| This program 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 General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include "dnsmasq.h" |
| |
| #ifdef __ANDROID__ |
| # include <android/log.h> |
| #endif |
| |
| /* Implement logging to /dev/log asynchronously. If syslogd is |
| making DNS lookups through dnsmasq, and dnsmasq blocks awaiting |
| syslogd, then the two daemons can deadlock. We get around this |
| by not blocking when talking to syslog, instead we queue up to |
| MAX_LOGS messages. If more are queued, they will be dropped, |
| and the drop event itself logged. */ |
| |
| /* The "wire" protocol for logging is defined in RFC 3164 */ |
| |
| /* From RFC 3164 */ |
| #define MAX_MESSAGE 1024 |
| |
| /* defaults in case we die() before we log_start() */ |
| static int log_fac = LOG_DAEMON; |
| static int log_stderr = 0; |
| static int echo_stderr = 0; |
| static int log_fd = -1; |
| static int log_to_file = 0; |
| static int entries_alloced = 0; |
| static int entries_lost = 0; |
| static int connection_good = 1; |
| static int max_logs = 0; |
| static int connection_type = SOCK_DGRAM; |
| |
| struct log_entry { |
| int offset, length; |
| pid_t pid; /* to avoid duplicates over a fork */ |
| struct log_entry *next; |
| char payload[MAX_MESSAGE]; |
| }; |
| |
| static struct log_entry *entries = NULL; |
| static struct log_entry *free_entries = NULL; |
| |
| |
| int log_start(struct passwd *ent_pw, int errfd) |
| { |
| int ret = 0; |
| |
| echo_stderr = option_bool(OPT_DEBUG); |
| |
| if (daemon->log_fac != -1) |
| log_fac = daemon->log_fac; |
| #ifdef LOG_LOCAL0 |
| else if (option_bool(OPT_DEBUG)) |
| log_fac = LOG_LOCAL0; |
| #endif |
| |
| if (daemon->log_file) |
| { |
| log_to_file = 1; |
| daemon->max_logs = 0; |
| if (strcmp(daemon->log_file, "-") == 0) |
| { |
| log_stderr = 1; |
| echo_stderr = 0; |
| log_fd = dup(STDERR_FILENO); |
| } |
| } |
| |
| max_logs = daemon->max_logs; |
| |
| if (!log_reopen(daemon->log_file)) |
| { |
| send_event(errfd, EVENT_LOG_ERR, errno, daemon->log_file ? daemon->log_file : ""); |
| _exit(0); |
| } |
| |
| /* if queuing is inhibited, make sure we allocate |
| the one required buffer now. */ |
| if (max_logs == 0) |
| { |
| free_entries = safe_malloc(sizeof(struct log_entry)); |
| free_entries->next = NULL; |
| entries_alloced = 1; |
| } |
| |
| /* If we're running as root and going to change uid later, |
| change the ownership here so that the file is always owned by |
| the dnsmasq user. Then logrotate can just copy the owner. |
| Failure of the chown call is OK, (for instance when started as non-root) */ |
| if (log_to_file && !log_stderr && ent_pw && ent_pw->pw_uid != 0 && |
| fchown(log_fd, ent_pw->pw_uid, -1) != 0) |
| ret = errno; |
| |
| return ret; |
| } |
| |
| int log_reopen(char *log_file) |
| { |
| if (!log_stderr) |
| { |
| if (log_fd != -1) |
| close(log_fd); |
| |
| /* NOTE: umask is set to 022 by the time this gets called */ |
| |
| if (log_file) |
| log_fd = open(log_file, O_WRONLY|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR|S_IRGRP); |
| else |
| { |
| #if defined(HAVE_SOLARIS_NETWORK) || defined(__ANDROID__) |
| /* Solaris logging is "different", /dev/log is not unix-domain socket. |
| Just leave log_fd == -1 and use the vsyslog call for everything.... */ |
| # define _PATH_LOG "" /* dummy */ |
| return 1; |
| #else |
| int flags; |
| log_fd = socket(AF_UNIX, connection_type, 0); |
| |
| /* if max_logs is zero, leave the socket blocking */ |
| if (log_fd != -1 && max_logs != 0 && (flags = fcntl(log_fd, F_GETFL)) != -1) |
| fcntl(log_fd, F_SETFL, flags | O_NONBLOCK); |
| #endif |
| } |
| } |
| |
| return log_fd != -1; |
| } |
| |
| static void free_entry(void) |
| { |
| struct log_entry *tmp = entries; |
| entries = tmp->next; |
| tmp->next = free_entries; |
| free_entries = tmp; |
| } |
| |
| static void log_write(void) |
| { |
| ssize_t rc; |
| |
| while (entries) |
| { |
| /* The data in the payoad is written with a terminating zero character |
| and the length reflects this. For a stream connection we need to |
| send the zero as a record terminator, but this isn't done for a |
| datagram connection, so treat the length as one less than reality |
| to elide the zero. If we're logging to a file, turn the zero into |
| a newline, and leave the length alone. */ |
| int len_adjust = 0; |
| |
| if (log_to_file) |
| entries->payload[entries->offset + entries->length - 1] = '\n'; |
| else if (connection_type == SOCK_DGRAM) |
| len_adjust = 1; |
| |
| /* Avoid duplicates over a fork() */ |
| if (entries->pid != getpid()) |
| { |
| free_entry(); |
| continue; |
| } |
| |
| connection_good = 1; |
| |
| if ((rc = write(log_fd, entries->payload + entries->offset, entries->length - len_adjust)) != -1) |
| { |
| entries->length -= rc; |
| entries->offset += rc; |
| if (entries->length == len_adjust) |
| { |
| free_entry(); |
| if (entries_lost != 0) |
| { |
| int e = entries_lost; |
| entries_lost = 0; /* avoid wild recursion */ |
| my_syslog(LOG_WARNING, _("overflow: %d log entries lost"), e); |
| } |
| } |
| continue; |
| } |
| |
| if (errno == EINTR) |
| continue; |
| |
| if (errno == EAGAIN || errno == EWOULDBLOCK) |
| return; /* syslogd busy, go again when select() or poll() says so */ |
| |
| if (errno == ENOBUFS) |
| { |
| connection_good = 0; |
| return; |
| } |
| |
| /* errors handling after this assumes sockets */ |
| if (!log_to_file) |
| { |
| /* Once a stream socket hits EPIPE, we have to close and re-open |
| (we ignore SIGPIPE) */ |
| if (errno == EPIPE) |
| { |
| if (log_reopen(NULL)) |
| continue; |
| } |
| else if (errno == ECONNREFUSED || |
| errno == ENOTCONN || |
| errno == EDESTADDRREQ || |
| errno == ECONNRESET) |
| { |
| /* socket went (syslogd down?), try and reconnect. If we fail, |
| stop trying until the next call to my_syslog() |
| ECONNREFUSED -> connection went down |
| ENOTCONN -> nobody listening |
| (ECONNRESET, EDESTADDRREQ are *BSD equivalents) */ |
| |
| struct sockaddr_un logaddr; |
| |
| #ifdef HAVE_SOCKADDR_SA_LEN |
| logaddr.sun_len = sizeof(logaddr) - sizeof(logaddr.sun_path) + strlen(_PATH_LOG) + 1; |
| #endif |
| logaddr.sun_family = AF_UNIX; |
| strncpy(logaddr.sun_path, _PATH_LOG, sizeof(logaddr.sun_path)); |
| |
| /* Got connection back? try again. */ |
| if (connect(log_fd, (struct sockaddr *)&logaddr, sizeof(logaddr)) != -1) |
| continue; |
| |
| /* errors from connect which mean we should keep trying */ |
| if (errno == ENOENT || |
| errno == EALREADY || |
| errno == ECONNREFUSED || |
| errno == EISCONN || |
| errno == EINTR || |
| errno == EAGAIN || |
| errno == EWOULDBLOCK) |
| { |
| /* try again on next syslog() call */ |
| connection_good = 0; |
| return; |
| } |
| |
| /* try the other sort of socket... */ |
| if (errno == EPROTOTYPE) |
| { |
| connection_type = connection_type == SOCK_DGRAM ? SOCK_STREAM : SOCK_DGRAM; |
| if (log_reopen(NULL)) |
| continue; |
| } |
| } |
| } |
| |
| /* give up - fall back to syslog() - this handles out-of-space |
| when logging to a file, for instance. */ |
| log_fd = -1; |
| my_syslog(LOG_CRIT, _("log failed: %s"), strerror(errno)); |
| return; |
| } |
| } |
| |
| /* priority is one of LOG_DEBUG, LOG_INFO, LOG_NOTICE, etc. See sys/syslog.h. |
| OR'd to priority can be MS_TFTP, MS_DHCP, ... to be able to do log separation between |
| DNS, DHCP and TFTP services. |
| */ |
| void my_syslog(int priority, const char *format, ...) |
| { |
| va_list ap; |
| struct log_entry *entry; |
| time_t time_now; |
| char *p; |
| size_t len; |
| pid_t pid = getpid(); |
| char *func = ""; |
| |
| if ((LOG_FACMASK & priority) == MS_TFTP) |
| func = "-tftp"; |
| else if ((LOG_FACMASK & priority) == MS_DHCP) |
| func = "-dhcp"; |
| |
| #ifdef LOG_PRI |
| priority = LOG_PRI(priority); |
| #else |
| /* Solaris doesn't have LOG_PRI */ |
| priority &= LOG_PRIMASK; |
| #endif |
| |
| if (echo_stderr) |
| { |
| fprintf(stderr, "dnsmasq%s: ", func); |
| va_start(ap, format); |
| vfprintf(stderr, format, ap); |
| va_end(ap); |
| fputc('\n', stderr); |
| } |
| |
| if (log_fd == -1) |
| { |
| #ifdef __ANDROID__ |
| /* do android-specific logging. |
| log_fd is always -1 on Android except when logging to a file. */ |
| int alog_lvl; |
| |
| if (priority <= LOG_ERR) |
| alog_lvl = ANDROID_LOG_ERROR; |
| else if (priority == LOG_WARNING) |
| alog_lvl = ANDROID_LOG_WARN; |
| else if (priority <= LOG_INFO) |
| alog_lvl = ANDROID_LOG_INFO; |
| else |
| alog_lvl = ANDROID_LOG_DEBUG; |
| |
| va_start(ap, format); |
| __android_log_vprint(alog_lvl, "dnsmasq", format, ap); |
| va_end(ap); |
| #else |
| /* fall-back to syslog if we die during startup or |
| fail during running (always on Solaris). */ |
| static int isopen = 0; |
| |
| if (!isopen) |
| { |
| openlog("dnsmasq", LOG_PID, log_fac); |
| isopen = 1; |
| } |
| va_start(ap, format); |
| vsyslog(priority, format, ap); |
| va_end(ap); |
| #endif |
| |
| return; |
| } |
| |
| if ((entry = free_entries)) |
| free_entries = entry->next; |
| else if (entries_alloced < max_logs && (entry = malloc(sizeof(struct log_entry)))) |
| entries_alloced++; |
| |
| if (!entry) |
| entries_lost++; |
| else |
| { |
| /* add to end of list, consumed from the start */ |
| entry->next = NULL; |
| if (!entries) |
| entries = entry; |
| else |
| { |
| struct log_entry *tmp; |
| for (tmp = entries; tmp->next; tmp = tmp->next); |
| tmp->next = entry; |
| } |
| |
| time(&time_now); |
| p = entry->payload; |
| if (!log_to_file) |
| p += sprintf(p, "<%d>", priority | log_fac); |
| |
| /* Omit timestamp for default daemontools situation */ |
| if (!log_stderr || !option_bool(OPT_NO_FORK)) |
| p += sprintf(p, "%.15s ", ctime(&time_now) + 4); |
| |
| p += sprintf(p, "dnsmasq%s[%d]: ", func, (int)pid); |
| |
| len = p - entry->payload; |
| va_start(ap, format); |
| len += vsnprintf(p, MAX_MESSAGE - len, format, ap) + 1; /* include zero-terminator */ |
| va_end(ap); |
| entry->length = len > MAX_MESSAGE ? MAX_MESSAGE : len; |
| entry->offset = 0; |
| entry->pid = pid; |
| } |
| |
| /* almost always, logging won't block, so try and write this now, |
| to save collecting too many log messages during a select loop. */ |
| log_write(); |
| |
| /* Since we're doing things asynchronously, a cache-dump, for instance, |
| can now generate log lines very fast. With a small buffer (desirable), |
| that means it can overflow the log-buffer very quickly, |
| so that the cache dump becomes mainly a count of how many lines |
| overflowed. To avoid this, we delay here, the delay is controlled |
| by queue-occupancy, and grows exponentially. The delay is limited to (2^8)ms. |
| The scaling stuff ensures that when the queue is bigger than 8, the delay |
| only occurs for the last 8 entries. Once the queue is full, we stop delaying |
| to preserve performance. |
| */ |
| |
| if (entries && max_logs != 0) |
| { |
| int d; |
| |
| for (d = 0,entry = entries; entry; entry = entry->next, d++); |
| |
| if (d == max_logs) |
| d = 0; |
| else if (max_logs > 8) |
| d -= max_logs - 8; |
| |
| if (d > 0) |
| { |
| struct timespec waiter; |
| waiter.tv_sec = 0; |
| waiter.tv_nsec = 1000000 << (d - 1); /* 1 ms */ |
| nanosleep(&waiter, NULL); |
| |
| /* Have another go now */ |
| log_write(); |
| } |
| } |
| } |
| |
| void set_log_writer(fd_set *set, int *maxfdp) |
| { |
| if (entries && log_fd != -1 && connection_good) |
| { |
| FD_SET(log_fd, set); |
| bump_maxfd(log_fd, maxfdp); |
| } |
| } |
| |
| void check_log_writer(fd_set *set) |
| { |
| if (log_fd != -1 && (!set || FD_ISSET(log_fd, set))) |
| log_write(); |
| } |
| |
| void flush_log(void) |
| { |
| /* write until queue empty, but don't loop forever if there's |
| no connection to the syslog in existance */ |
| while (log_fd != -1) |
| { |
| struct timespec waiter; |
| log_write(); |
| if (!entries || !connection_good) |
| { |
| close(log_fd); |
| break; |
| } |
| waiter.tv_sec = 0; |
| waiter.tv_nsec = 1000000; /* 1 ms */ |
| nanosleep(&waiter, NULL); |
| } |
| } |
| |
| void die(char *message, char *arg1, int exit_code) |
| { |
| char *errmess = strerror(errno); |
| |
| if (!arg1) |
| arg1 = errmess; |
| |
| if (!log_stderr) |
| { |
| echo_stderr = 1; /* print as well as log when we die.... */ |
| fputc('\n', stderr); /* prettyfy startup-script message */ |
| } |
| my_syslog(LOG_CRIT, message, arg1, errmess); |
| echo_stderr = 0; |
| my_syslog(LOG_CRIT, _("FAILED to start up")); |
| flush_log(); |
| |
| exit(exit_code); |
| } |