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toaruos/apps/dhclient.c

447 lines
11 KiB
C
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#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <poll.h>
#include <dirent.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <net/if.h>
struct ethernet_packet {
uint8_t destination[6];
uint8_t source[6];
uint16_t type;
uint8_t payload[];
} __attribute__((packed)) __attribute__((aligned(2)));
struct ipv4_packet {
uint8_t version_ihl;
uint8_t dscp_ecn;
uint16_t length;
uint16_t ident;
uint16_t flags_fragment;
uint8_t ttl;
uint8_t protocol;
uint16_t checksum;
uint32_t source;
uint32_t destination;
uint8_t payload[];
} __attribute__ ((packed)) __attribute__((aligned(2)));
struct udp_packet {
uint16_t source_port;
uint16_t destination_port;
uint16_t length;
uint16_t checksum;
uint8_t payload[];
} __attribute__ ((packed)) __attribute__((aligned(2)));
struct dhcp_packet {
uint8_t op;
uint8_t htype;
uint8_t hlen;
uint8_t hops;
uint32_t xid;
uint16_t secs;
uint16_t flags;
uint32_t ciaddr;
uint32_t yiaddr;
uint32_t siaddr;
uint32_t giaddr;
uint8_t chaddr[16];
uint8_t sname[64];
uint8_t file[128];
uint32_t magic;
uint8_t options[];
} __attribute__ ((packed)) __attribute__((aligned(2)));
struct dns_packet {
uint16_t qid;
uint16_t flags;
uint16_t questions;
uint16_t answers;
uint16_t authorities;
uint16_t additional;
uint8_t data[];
} __attribute__ ((packed)) __attribute__((aligned(2)));
struct tcp_header {
uint16_t source_port;
uint16_t destination_port;
uint32_t seq_number;
uint32_t ack_number;
uint16_t flags;
uint16_t window_size;
uint16_t checksum;
uint16_t urgent;
uint8_t payload[];
} __attribute__((packed)) __attribute__((aligned(2)));
struct tcp_check_header {
uint32_t source;
uint32_t destination;
uint8_t zeros;
uint8_t protocol;
uint16_t tcp_len;
uint8_t tcp_header[];
};
#define SOCK_STREAM 1
#define SOCK_DGRAM 2
// Note: Data offset is in upper 4 bits of flags field. Shift and subtract 5 since that is the min TCP size.
// If the value is more than 5, multiply by 4 because this field is specified in number of words
#define TCP_OPTIONS_LENGTH(tcp) (((((tcp)->flags) >> 12) - 5) * 4)
#define TCP_HEADER_LENGTH(tcp) ((((tcp)->flags) >> 12) * 4)
#define TCP_HEADER_LENGTH_FLIPPED(tcp) (((htons((tcp)->flags)) >> 12) * 4)
#define htonl(l) ( (((l) & 0xFF) << 24) | (((l) & 0xFF00) << 8) | (((l) & 0xFF0000) >> 8) | (((l) & 0xFF000000) >> 24))
#define htons(s) ( (((s) & 0xFF) << 8) | (((s) & 0xFF00) >> 8) )
#define ntohl(l) htonl((l))
#define ntohs(s) htons((s))
#define BROADCAST_MAC {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}
#define IPV4_PROT_UDP 17
#define IPV4_PROT_TCP 6
#define DHCP_MAGIC 0x63825363
#define TCP_FLAGS_FIN (1 << 0)
#define TCP_FLAGS_SYN (1 << 1)
#define TCP_FLAGS_RES (1 << 2)
#define TCP_FLAGS_PSH (1 << 3)
#define TCP_FLAGS_ACK (1 << 4)
#define TCP_FLAGS_URG (1 << 5)
#define TCP_FLAGS_ECE (1 << 6)
#define TCP_FLAGS_CWR (1 << 7)
#define TCP_FLAGS_NS (1 << 8)
#define DATA_OFFSET_5 (0x5 << 12)
#define ETHERNET_TYPE_IPV4 0x0800
#define ETHERNET_TYPE_ARP 0x0806
struct payload {
struct ethernet_packet eth_header;
struct ipv4_packet ip_header;
struct udp_packet udp_header;
struct dhcp_packet dhcp_header;
uint8_t payload[32];
};
static void ip_ntoa(const uint32_t src_addr, char * out) {
snprintf(out, 16, "%d.%d.%d.%d",
(src_addr & 0xFF000000) >> 24,
(src_addr & 0xFF0000) >> 16,
(src_addr & 0xFF00) >> 8,
(src_addr & 0xFF));
}
uint16_t calculate_ipv4_checksum(struct ipv4_packet * p) {
uint32_t sum = 0;
uint16_t * s = (uint16_t *)p;
/* TODO: Checksums for options? */
for (int i = 0; i < 10; ++i) {
sum += ntohs(s[i]);
}
if (sum > 0xFFFF) {
sum = (sum >> 16) + (sum & 0xFFFF);
}
return ~(sum & 0xFFFF) & 0xFFFF;
}
uint8_t mac_addr[6];
uint32_t xid = 0x1337;
void fill(struct payload *it, size_t payload_size) {
it->eth_header.source[0] = mac_addr[0];
it->eth_header.source[1] = mac_addr[1];
it->eth_header.source[2] = mac_addr[2];
it->eth_header.source[3] = mac_addr[3];
it->eth_header.source[4] = mac_addr[4];
it->eth_header.source[5] = mac_addr[5];
it->eth_header.destination[0] = 0xFF;
it->eth_header.destination[1] = 0xFF;
it->eth_header.destination[2] = 0xFF;
it->eth_header.destination[3] = 0xFF;
it->eth_header.destination[4] = 0xFF;
it->eth_header.destination[5] = 0xFF;
it->eth_header.type = htons(0x0800);
it->ip_header.version_ihl = ((0x4 << 4) | (0x5 << 0));
it->ip_header.dscp_ecn = 0;
it->ip_header.length = htons(sizeof(struct ipv4_packet) + sizeof(struct udp_packet) + sizeof(struct dhcp_packet) + payload_size);
it->ip_header.ident = htons(1);
it->ip_header.flags_fragment = 0;
it->ip_header.ttl = 0x40;
it->ip_header.protocol = IPV4_PROT_UDP;
it->ip_header.checksum = 0;
it->ip_header.source = htonl(0);
it->ip_header.destination = htonl(0xFFFFFFFF);
it->ip_header.checksum = htons(calculate_ipv4_checksum(&it->ip_header));
it->udp_header.source_port = htons(68);
it->udp_header.destination_port = htons(67);
it->udp_header.length = htons(sizeof(struct udp_packet) + sizeof(struct dhcp_packet) + payload_size);
it->udp_header.checksum = 0; /* uh */
it->dhcp_header.op = 1;
it->dhcp_header.htype = 1;
it->dhcp_header.hlen = 6;
it->dhcp_header.hops = 0;
it->dhcp_header.xid = htonl(xid); /* transaction id... */
it->dhcp_header.secs = 0;
it->dhcp_header.flags = 0;
it->dhcp_header.ciaddr = 0;
it->dhcp_header.yiaddr = 0;
it->dhcp_header.siaddr = 0;
it->dhcp_header.giaddr = 0;
it->dhcp_header.chaddr[0] = mac_addr[0];
it->dhcp_header.chaddr[1] = mac_addr[1];
it->dhcp_header.chaddr[2] = mac_addr[2];
it->dhcp_header.chaddr[3] = mac_addr[3];
it->dhcp_header.chaddr[4] = mac_addr[4];
it->dhcp_header.chaddr[5] = mac_addr[5];
it->dhcp_header.magic = htonl(DHCP_MAGIC);
}
static void time_diff(struct timeval *start, struct timeval *end, time_t *sec_diff, suseconds_t *usec_diff) {
*sec_diff = end->tv_sec - start->tv_sec;
*usec_diff = end->tv_usec - start->tv_usec;
if (end->tv_usec < start->tv_usec) {
*sec_diff -= 1;
*usec_diff = (1000000 + end->tv_usec) - start->tv_usec;
}
}
extern char * _argv_0;
static int configure_interface(const char * if_name) {
/* Open a raw socket. */
int sock = socket(AF_RAW, SOCK_RAW, 0);
if (!sock) {
perror(_argv_0);
return 1;
}
/* Bind to this interface */
if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, if_name, strlen(if_name)+1)) {
perror(_argv_0);
return 1;
}
/* Request the mac address */
char if_path[100];
snprintf(if_path, 100, "/dev/net/%s", if_name);
int netdev = open(if_path, O_RDWR);
if (netdev < 0) {
perror(_argv_0);
return 1;
}
if (ioctl(netdev, SIOCGIFHWADDR, &mac_addr)) {
fprintf(stderr, "%s: %s: could not get mac address\n", _argv_0, if_name);
return 1;
}
xid = rand();
/* Try to frob the whatsit */
{
struct payload thething = {
.payload = {53,1,1,55,2,3,6,255,0}
};
fill(&thething, 8);
send(sock, &thething, sizeof(struct payload), 0);
}
uint32_t yiaddr;
int stage = 1;
struct timeval start, end;
time_t sec_diff;
suseconds_t usec_diff;
gettimeofday(&start, NULL);
static uint8_t eth_broadcast[6] = {255,255,255,255,255,255};
do {
char buf[8192] = {0};
gettimeofday(&end, NULL);
time_diff(&start,&end,&sec_diff,&usec_diff);
if (sec_diff > 2) {
close(netdev);
return 1;
}
struct pollfd fds[1];
fds[0].fd = sock;
fds[0].events = POLLIN;
int ret = poll(fds,1,200);
if (ret == 0) {
continue;
}
if (ret < 0) {
fprintf(stderr, "poll: failed\n");
return 1;
}
ssize_t rsize = recv(sock, &buf, 8192, 0);
if (rsize <= 0) {
fprintf(stderr, "%s: %s: bad size? %zd\n", _argv_0, if_name, rsize);
continue;
}
struct payload * response = (void*)buf;
if (memcmp(response->eth_header.destination,mac_addr,6) &&
memcmp(response->eth_header.destination,eth_broadcast,6)) {
/* Not ours */
continue;
}
if (ntohs(response->udp_header.destination_port) != 68) {
/* Not DHCP */
continue;
}
if (ntohl(response->dhcp_header.xid) != xid) {
/* Not our transaction */
continue;
}
if (stage == 1) {
yiaddr = response->dhcp_header.yiaddr;
struct payload thething = {
.payload = {53,1,3,50,4,
(yiaddr) & 0xFF,
(yiaddr >> 8) & 0xFF,
(yiaddr >> 16) & 0xFF,
(yiaddr >> 24) & 0xFF,
55,2,3,6,255,0}
};
fill(&thething, 14);
send(sock, &thething, sizeof(struct payload), 0);
stage = 2;
gettimeofday(&start, NULL);
} else if (stage == 2) {
yiaddr = response->dhcp_header.yiaddr;
char yiaddr_ip[16];
ip_ntoa(ntohl(yiaddr), yiaddr_ip);
if (!ioctl(netdev, SIOCSIFADDR, &yiaddr)) {
printf("%s: %s: configured for %s\n", _argv_0, if_name, yiaddr_ip);
} else {
perror(_argv_0);
}
/* See if we got a gateway and subnet out of it as well, those are cool... */
uint8_t * opt = response->dhcp_header.options;
while (*opt && *opt != 255) {
uint8_t opt_type = *opt++;
uint8_t len = *opt++;
if (opt_type == 1) {
/* Subnet mask */
uint32_t ip_data;
memcpy(&ip_data, opt, 4);
char addr[16];
ip_ntoa(ntohl(ip_data), addr);
printf("%s: %s: subnet mask %s\n", _argv_0, if_name, addr);
ioctl(netdev, SIOCSIFNETMASK, &ip_data);
} else if (opt_type == 3) {
/* Gateway address - add this to a route table? */
uint32_t ip_data;
memcpy(&ip_data, opt, 4);
char addr[16];
ip_ntoa(ntohl(ip_data), addr);
printf("%s: %s: gateway %s\n", _argv_0, if_name, addr);
ioctl(netdev, SIOCSIFGATEWAY, &ip_data);
} else if (opt_type == 6) {
/* DNS server */
uint32_t ip_data;
memcpy(&ip_data, opt, 4);
char addr[16];
ip_ntoa(ntohl(ip_data), addr);
printf("%s: %s: nameserver %s\n", _argv_0, if_name, addr);
FILE * resolve = fopen("/etc/resolv.conf","w");
if (!resolve) resolve = fopen("/var/resolv.conf","w");
if (resolve) {
fprintf(resolve, "nameserver %s\n", addr);
fclose(resolve);
} /* else, read-only file system? */
}
opt += len;
}
close(netdev);
close(sock);
return 0;
}
} while (1);
return 1;
}
static int configure_interface_with_backoff(const char * if_name) {
int sleep_times[] = {1,3,5,0};
for (int *time = sleep_times; *time; time++) {
if (!configure_interface(if_name)) return 0;
sleep(*time);
}
return 1;
}
int main(int argc, char * argv[]) {
int retval = 0;
if (argc > 1) {
return configure_interface(argv[1]);
} else {
/* Read /dev/net for interfaces */
DIR * d = opendir("/dev/net");
if (!d) {
fprintf(stderr, "%s: no network?\n", _argv_0);
return 1;
}
struct dirent * ent;
while ((ent = readdir(d))) {
if (ent->d_name[0] == '.') continue;
if (configure_interface_with_backoff(ent->d_name)) {
retval = 1;
}
}
closedir(d);
}
return retval;
}
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