Add safe_read() to ncmlib and use it in ndhc.
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26
ncmlib/io.c
26
ncmlib/io.c
@ -1,5 +1,5 @@
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/* io.c - light wrappers for POSIX i/o functions
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* Time-stamp: <2010-11-13 08:08:39 njk>
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* Time-stamp: <2010-11-13 08:22:53 njk>
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*
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* (c) 2010 Nicholas J. Kain <njkain at gmail dot com>
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* All rights reserved.
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@ -30,11 +30,29 @@
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#include <unistd.h>
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#include <errno.h>
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// returns -1 on error, >= 0 on success
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/* returns -1 on error, >= 0 and equal to # chars read on success */
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int safe_read(int fd, char *buf, int len)
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{
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int r, s = 0;
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while (s < len) {
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r = read(fd, buf + s, len - s);
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if (r == 0)
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break;
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if (r == -1) {
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if (errno == EINTR)
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continue;
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else
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return -1;
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}
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s += r;
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}
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return s;
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}
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/* returns -1 on error, >= 0 and equal to # chars written on success */
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int safe_write(int fd, const char *buf, int len)
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{
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int r;
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int s = 0;
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int r, s = 0;
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while (s < len) {
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r = write(fd, buf + s, len - s);
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if (r == -1) {
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@ -1,5 +1,5 @@
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/* io.h - light wrappers for POSIX i/o functions
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* Time-stamp: <2010-11-13 08:07:43 njk>
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* Time-stamp: <2010-11-13 08:22:48 njk>
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*
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* (c) 2010 Nicholas J. Kain <njkain at gmail dot com>
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* All rights reserved.
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@ -30,6 +30,7 @@
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#ifndef NCM_IO_H_
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#define NCM_IO_H_
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int safe_read(int fd, char *buf, int len);
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int safe_write(int fd, const char *buf, int len);
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#endif /* NCM_IO_H_ */
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@ -41,26 +41,31 @@
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#include "options.h"
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#include "dhcpc.h"
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#include "log.h"
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#include "io.h"
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/* Create a random xid */
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uint32_t random_xid(void)
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{
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static int initialized;
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if (!initialized) {
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int fd;
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uint32_t seed;
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if (initialized)
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return rand();
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fd = open("/dev/urandom", O_RDONLY);
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if (fd == -1 || read(fd, &seed, sizeof seed) < 0) {
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log_warning("Could not load seed from /dev/urandom: %s",
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strerror(errno));
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seed = time(0);
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uint32_t seed;
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int fd = open("/dev/urandom", O_RDONLY);
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if (fd != -1) {
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int r = safe_read(fd, (char *)&seed, sizeof seed);
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if (r == -1) {
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log_warning("Could not read /dev/urandom: %s", strerror(errno));
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close(fd);
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seed = time(0);
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}
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if (fd != -1)
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close(fd);
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srand(seed);
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initialized++;
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} else {
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log_warning("Could not open /dev/urandom: %s",
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strerror(errno));
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seed = time(0);
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}
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srand(seed);
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initialized = 1;
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return rand();
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}
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@ -178,24 +183,15 @@ int get_raw_packet(struct dhcpMessage *payload, int fd)
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struct udp_dhcp_packet packet;
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uint32_t source, dest;
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uint16_t check;
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ssize_t len = 0;
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const ssize_t header_size = sizeof(struct iphdr) + sizeof(struct udphdr);
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const ssize_t packet_size = sizeof(struct udp_dhcp_packet);
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const int header_size = sizeof(struct iphdr) + sizeof(struct udphdr);
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const int packet_size = sizeof(struct udp_dhcp_packet);
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memset(&packet, 0, packet_size);
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while (len < packet_size) {
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ssize_t r = read(fd, ((char *)&packet) + len, packet_size - len);
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if (r == 0)
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break;
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if (r == -1) {
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if (errno == EINTR)
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continue;
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log_line("get_raw_packet: read error %s", strerror(errno));
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usleep(500000); /* possible down interface, looping condition */
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return -1;
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}
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len += r;
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int len = safe_read(fd, (char *)&packet, packet_size);
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if (len == -1) {
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log_line("get_raw_packet: read error %s", strerror(errno));
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usleep(500000); /* possible down interface, looping condition */
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return -1;
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}
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if (len < header_size) {
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@ -48,9 +48,9 @@ int get_packet(struct dhcpMessage *packet, int fd)
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unsigned char *vendor;
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memset(packet, 0, sizeof(struct dhcpMessage));
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bytes = read(fd, packet, sizeof(struct dhcpMessage));
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if (bytes < 0) {
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log_line("couldn't read on listening socket, ignoring");
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bytes = safe_read(fd, (char *)packet, sizeof(struct dhcpMessage));
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if (bytes == -1) {
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log_line("read on listen socket failed: %s", strerror(errno));
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return -1;
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}
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