From 448f4696f10c0f2fb75b8ad6230043d3d5e794fa Mon Sep 17 00:00:00 2001 From: Jo-Philipp Wich Date: Mon, 27 Feb 2012 22:57:15 +0000 Subject: add iwcap - a small radiotap capture utility for background monitoring of wireless traffic or use as a remote capture drone SVN-Revision: 30747 --- package/iwcap/Makefile | 50 ++++ package/iwcap/src/iwcap.c | 582 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 632 insertions(+) create mode 100644 package/iwcap/Makefile create mode 100644 package/iwcap/src/iwcap.c (limited to 'package/iwcap') diff --git a/package/iwcap/Makefile b/package/iwcap/Makefile new file mode 100644 index 0000000000..b406bdfb4f --- /dev/null +++ b/package/iwcap/Makefile @@ -0,0 +1,50 @@ +# +# Copyright (C) 2012 Jo-Philipp Wich +# +# This is free software, licensed under the Apache 2 license. +# + +include $(TOPDIR)/rules.mk + +PKG_NAME:=iwcap +PKG_RELEASE:=1 + +include $(INCLUDE_DIR)/package.mk + + +define Package/iwcap + SECTION:=utils + CATEGORY:=Utilities + TITLE:=Simple radiotap capture utility + MAINTAINER:=Jo-Philipp Wich +endef + +define Package/iwcap/description + The iwcap utility receives radiotap packet data from wifi monitor interfaces + and outputs it to pcap format. It gathers recived packets in a fixed ring + buffer to dump them on demand which is useful for background monitoring. + Alternatively the utility can stream the data to stdout to act as remote + capture drone for Wireshark or similar programs. +endef + + +define Build/Prepare + $(INSTALL_DIR) $(PKG_BUILD_DIR) + $(CP) ./src/* $(PKG_BUILD_DIR)/ +endef + +define Build/Configure +endef + +define Build/Compile + $(TARGET_CC) $(TARGET_CFLAGS) \ + -o $(PKG_BUILD_DIR)/iwcap $(PKG_BUILD_DIR)/iwcap.c +endef + + +define Package/iwcap/install + $(INSTALL_DIR) $(1)/usr/sbin + $(INSTALL_BIN) $(PKG_BUILD_DIR)/iwcap $(1)/usr/sbin/iwcap +endef + +$(eval $(call BuildPackage,iwcap)) diff --git a/package/iwcap/src/iwcap.c b/package/iwcap/src/iwcap.c new file mode 100644 index 0000000000..3a8e7404da --- /dev/null +++ b/package/iwcap/src/iwcap.c @@ -0,0 +1,582 @@ +/* + * iwcap.c - A simply radiotap capture utility outputting pcap sig_dumps + * + * Copyright 2012 Jo-Philipp Wich + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define ARPHRD_IEEE80211_RADIOTAP 803 + +#define DLT_IEEE802_11_RADIO 127 +#define LEN_IEEE802_11_HDR 32 + +#define FRAMETYPE_MASK 0xFC +#define FRAMETYPE_BEACON 0x80 +#define FRAMETYPE_DATA 0x08 + +#if __BYTE_ORDER == __BIG_ENDIAN +#define le16(x) __bswap_16(x) +#else +#define le16(x) (x) +#endif + +uint8_t run_dump = 0; +uint8_t run_stop = 0; +uint8_t run_daemon = 0; + +uint32_t frames_captured = 0; +uint32_t frames_filtered = 0; + +int capture_sock = -1; +const char *ifname = NULL; + + +struct ringbuf { + uint32_t len; /* number of slots */ + uint32_t fill; /* last used slot */ + uint32_t slen; /* slot size */ + void *buf; /* ring memory */ +}; + +struct ringbuf_entry { + uint32_t len; /* used slot memory */ + uint32_t olen; /* original data size */ + uint32_t sec; /* epoch of slot creation */ + uint32_t usec; /* epoch microseconds */ +}; + +typedef struct pcap_hdr_s { + uint32_t magic_number; /* magic number */ + uint16_t version_major; /* major version number */ + uint16_t version_minor; /* minor version number */ + int32_t thiszone; /* GMT to local correction */ + uint32_t sigfigs; /* accuracy of timestamps */ + uint32_t snaplen; /* max length of captured packets, in octets */ + uint32_t network; /* data link type */ +} pcap_hdr_t; + +typedef struct pcaprec_hdr_s { + uint32_t ts_sec; /* timestamp seconds */ + uint32_t ts_usec; /* timestamp microseconds */ + uint32_t incl_len; /* number of octets of packet saved in file */ + uint32_t orig_len; /* actual length of packet */ +} pcaprec_hdr_t; + +typedef struct ieee80211_radiotap_header { + u_int8_t it_version; /* set to 0 */ + u_int8_t it_pad; + u_int16_t it_len; /* entire length */ + u_int32_t it_present; /* fields present */ +} __attribute__((__packed__)) radiotap_hdr_t; + + +int check_type(void) +{ + struct ifreq ifr; + + strncpy(ifr.ifr_name, ifname, IFNAMSIZ); + + if (ioctl(capture_sock, SIOCGIFHWADDR, &ifr) < 0) + return -1; + + return (ifr.ifr_hwaddr.sa_family == ARPHRD_IEEE80211_RADIOTAP); +} + +int set_promisc(int on) +{ + struct ifreq ifr; + + strncpy(ifr.ifr_name, ifname, IFNAMSIZ); + + if (ioctl(capture_sock, SIOCGIFFLAGS, &ifr) < 0) + return -1; + + if (on && !(ifr.ifr_flags & IFF_PROMISC)) + { + ifr.ifr_flags |= IFF_PROMISC; + + if (ioctl(capture_sock, SIOCSIFFLAGS, &ifr)) + return -1; + + return 1; + } + else if (!on && (ifr.ifr_flags & IFF_PROMISC)) + { + ifr.ifr_flags &= ~IFF_PROMISC; + + if (ioctl(capture_sock, SIOCSIFFLAGS, &ifr)) + return -1; + + return 1; + } + + return 0; +} + + +void sig_dump(int sig) +{ + run_dump = 1; +} + +void sig_teardown(int sig) +{ + run_stop = 1; +} + + +void write_pcap_header(FILE *o) +{ + pcap_hdr_t ghdr = { + .magic_number = 0xa1b2c3d4, + .version_major = 2, + .version_minor = 4, + .thiszone = 0, + .sigfigs = 0, + .snaplen = 0xFFFF, + .network = DLT_IEEE802_11_RADIO + }; + + fwrite(&ghdr, 1, sizeof(ghdr), o); +} + +void write_pcap_frame(FILE *o, uint32_t *sec, uint32_t *usec, + uint16_t len, uint16_t olen) +{ + struct timeval tv; + pcaprec_hdr_t fhdr; + + if (!sec || !usec) + { + gettimeofday(&tv, NULL); + } + else + { + tv.tv_sec = *sec; + tv.tv_usec = *usec; + } + + fhdr.ts_sec = tv.tv_sec; + fhdr.ts_usec = tv.tv_usec; + fhdr.incl_len = len; + fhdr.orig_len = olen; + + fwrite(&fhdr, 1, sizeof(fhdr), o); +} + + +struct ringbuf * ringbuf_init(uint32_t num_item, uint16_t len_item) +{ + static struct ringbuf r; + + if (len_item <= 0) + return NULL; + + r.buf = malloc(num_item * (len_item + sizeof(struct ringbuf_entry))); + + if (r.buf) + { + r.len = num_item; + r.fill = 0; + r.slen = (len_item + sizeof(struct ringbuf_entry)); + + memset(r.buf, 0, num_item * len_item); + + return &r; + } + + return NULL; +} + +struct ringbuf_entry * ringbuf_add(struct ringbuf *r) +{ + struct timeval t; + struct ringbuf_entry *e; + + gettimeofday(&t, NULL); + + e = r->buf + (r->fill++ * r->slen); + r->fill %= r->len; + + memset(e, 0, r->slen); + + e->sec = t.tv_sec; + e->usec = t.tv_usec; + + return e; +} + +struct ringbuf_entry * ringbuf_get(struct ringbuf *r, int i) +{ + struct ringbuf_entry *e = r->buf + (((r->fill + i) % r->len) * r->slen); + + if (e->len > 0) + return e; + + return NULL; +} + +void ringbuf_free(struct ringbuf *r) +{ + free(r->buf); + memset(r, 0, sizeof(*r)); +} + + +void msg(const char *fmt, ...) +{ + va_list ap; + va_start(ap, fmt); + + if (run_daemon) + vsyslog(LOG_INFO | LOG_USER, fmt, ap); + else + vfprintf(stderr, fmt, ap); + + va_end(ap); +} + + +int main(int argc, char **argv) +{ + int i, n; + struct ringbuf *ring; + struct ringbuf_entry *e; + struct sockaddr_ll local = { + .sll_family = AF_PACKET, + .sll_protocol = htons(ETH_P_ALL) + }; + + radiotap_hdr_t *rhdr; + + uint8_t frametype; + uint8_t pktbuf[0xFFFF]; + ssize_t pktlen; + + FILE *o; + + int opt; + + uint8_t promisc = 0; + uint8_t streaming = 0; + uint8_t foreground = 0; + uint8_t filter_data = 0; + uint8_t filter_beacon = 0; + uint8_t header_written = 0; + + uint32_t ringsz = 1024 * 1024; /* 1 Mbyte ring buffer */ + uint16_t pktcap = 256; /* truncate frames after 265KB */ + + const char *output = NULL; + + + while ((opt = getopt(argc, argv, "i:r:c:o:sfhBD")) != -1) + { + switch (opt) + { + case 'i': + ifname = optarg; + if (!(local.sll_ifindex = if_nametoindex(ifname))) + { + msg("Unknown interface '%s'\n", ifname); + return 2; + } + break; + + case 'r': + ringsz = atoi(optarg); + if (ringsz < (3 * pktcap)) + { + msg("Ring size of %d bytes is too short, " + "must be at least %d bytes\n", ringsz, 3 * pktcap); + return 3; + } + break; + + case 'c': + pktcap = atoi(optarg); + if (pktcap <= (sizeof(radiotap_hdr_t) + LEN_IEEE802_11_HDR)) + { + msg("Packet truncate after %d bytes is too short, " + "must be at least %d bytes\n", + pktcap, sizeof(radiotap_hdr_t) + LEN_IEEE802_11_HDR); + return 4; + } + break; + + case 's': + streaming = 1; + break; + + case 'o': + output = optarg; + break; + + case 'B': + filter_beacon = 1; + break; + + case 'D': + filter_data = 1; + break; + + case 'f': + foreground = 1; + break; + + case 'h': + msg( + "Usage:\n" + " %s -i {iface} -s [-b] [-d]\n" + " %s -i {iface} -o {file} [-r len] [-c len] [-B] [-D] [-f]\n" + "\n" + " -i iface\n" + " Specify interface to use, must be in monitor mode and\n" + " produce IEEE 802.11 Radiotap headers.\n\n" + " -s\n" + " Stream to stdout instead of Dumping to file on USR1.\n\n" + " -o file\n" + " Write current ringbuffer contents to given output file\n" + " on receipt of SIGUSR1.\n\n" + " -r len\n" + " Specify the amount of bytes to use for the ringbuffer.\n" + " The default length is %d bytes.\n\n" + " -c len\n" + " Truncate captured packets after given amount of bytes.\n" + " The default size limit is %d bytes.\n\n" + " -B\n" + " Don't store beacon frames in ring, default is keep.\n\n" + " -D\n" + " Don't store data frames in ring, default is keep.\n\n" + " -f\n" + " Do not daemonize but keep running in foreground.\n\n" + " -h\n" + " Display this help.\n\n", + argv[0], argv[0], ringsz, pktcap); + + return 1; + } + } + + if (!streaming && !output) + { + msg("No output file specified\n"); + return 1; + } + + if (streaming && output) + { + msg("The -s and -o options are exclusive\n"); + return 1; + } + + if (streaming && isatty(1)) + { + msg("Refusing to stream into a terminal\n"); + return 1; + } + + if (!local.sll_ifindex) + { + msg("No interface specified\n"); + return 2; + } + + if (!check_type()) + { + msg("Bad interface: not ARPHRD_IEEE80211_RADIOTAP\n"); + return 2; + } + + if ((capture_sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))) < 0) + { + msg("Unable to create raw socket: %s\n", + strerror(errno)); + return 6; + } + + if (bind(capture_sock, (struct sockaddr *)&local, sizeof(local)) == -1) + { + msg("Unable to bind to interface: %s\n", + strerror(errno)); + return 7; + } + + if (!streaming) + { + if (!foreground) + { + switch (fork()) + { + case -1: + msg("Unable to fork: %s\n", strerror(errno)); + return 8; + + case 0: + umask(0700); + chdir("/"); + freopen("/dev/null", "r", stdin); + freopen("/dev/null", "w", stdout); + freopen("/dev/null", "w", stderr); + run_daemon = 1; + break; + + default: + msg("Daemon launched ...\n"); + return 0; + } + } + + msg("Monitoring interface %s ...\n", ifname); + + if (!(ring = ringbuf_init(ringsz / pktcap, pktcap))) + { + msg("Unable to allocate ring buffer: %s\n", + strerror(errno)); + return 5; + } + + msg(" * Using %d bytes ringbuffer with %d slots\n", ringsz, ring->len); + msg(" * Truncating frames at %d bytes\n", pktcap); + msg(" * Dumping data to file %s\n", output); + + signal(SIGUSR1, sig_dump); + } + else + { + msg("Monitoring interface %s ...\n", ifname); + msg(" * Streaming data to stdout\n"); + } + + msg(" * Beacon frames are %sfiltered\n", filter_beacon ? "" : "not "); + msg(" * Data frames are %sfiltered\n", filter_data ? "" : "not "); + + signal(SIGINT, sig_teardown); + signal(SIGTERM, sig_teardown); + + promisc = set_promisc(1); + + /* capture loop */ + while (1) + { + if (run_stop) + { + msg("Shutting down ...\n"); + + if (promisc) + set_promisc(0); + + if (ring) + ringbuf_free(ring); + + return 0; + } + else if (run_dump) + { + msg("Dumping ring to %s ...\n", output); + + if (!(o = fopen(output, "w"))) + { + msg("Unable to open %s: %s\n", + output, strerror(errno)); + } + else + { + write_pcap_header(o); + + /* sig_dump packet buffer */ + for (i = 0, n = 0; i < ring->len; i++) + { + if (!(e = ringbuf_get(ring, i))) + continue; + + write_pcap_frame(o, &(e->sec), &(e->usec), e->len, e->olen); + fwrite((void *)e + sizeof(*e), 1, e->len, o); + n++; + } + + fclose(o); + + msg(" * %d frames captured\n", frames_captured); + msg(" * %d frames filtered\n", frames_filtered); + msg(" * %d frames dumped\n", n); + } + + run_dump = 0; + } + + pktlen = recvfrom(capture_sock, pktbuf, sizeof(pktbuf), 0, NULL, 0); + frames_captured++; + + /* check received frametype, if we should filter it, rewind the ring */ + rhdr = (radiotap_hdr_t *)pktbuf; + + if (pktlen <= sizeof(radiotap_hdr_t) || le16(rhdr->it_len) >= pktlen) + { + frames_filtered++; + continue; + } + + frametype = *(uint8_t *)(pktbuf + le16(rhdr->it_len)); + + if ((filter_data && (frametype & FRAMETYPE_MASK) == FRAMETYPE_DATA) || + (filter_beacon && (frametype & FRAMETYPE_MASK) == FRAMETYPE_BEACON)) + { + frames_filtered++; + continue; + } + + if (streaming) + { + if (!header_written) + { + write_pcap_header(stdout); + header_written = 1; + } + + write_pcap_frame(stdout, NULL, NULL, pktlen, pktlen); + fwrite(pktbuf, 1, pktlen, stdout); + fflush(stdout); + } + else + { + e = ringbuf_add(ring); + e->olen = pktlen; + e->len = (pktlen > pktcap) ? pktcap : pktlen; + + memcpy((void *)e + sizeof(*e), pktbuf, e->len); + } + } + + return 0; +} -- cgit v1.2.3