I am trying to use Libnet11 function:
int libnet_write_raw_ipv6 (libnet_t *l, u_int8_t *packet, u_int32_t size)
to inject IPv6 packet on network layer.
I had created IPv6 packet and captured it
with Wireshark. Wireshark reported:
malformed packet(wireshark says that next
header value in IPv6 is wrong and payload
size is too big in my opinion)
I hope, someone could help me with minimal code example,
showing how to manually build IPv6 packet (with ICMPv6
extension header) with libnet11 (libnet_write_raw_ipv6()).
I assume that the minimal code might look like this:
packet_len = 40 + 16; // 40B ~ IPv6 packet, 16B ~ ICMPv6 header
u_char *buf = NULL;
struct ip6_hdr *ip6 = NULL;
struct icmp6_hdr *icmp6 = NULL;
l = libnet_init();
if ( (buf = malloc(packet_len)) == NULL ) {
// error
}
// create IPv6 header
ip6 = (struct ip6_hdr *) buf;
ip6->ip6_flow = 0;
ip6->ip6_vfc = 6 << 4;
ip6->ip6_plen = 16; // ICMPv6 packet size
ip6->ip6_nxt = IPPROTO_ICMPV6; // 0x3a
ip6->ip6_hlim = 64;
memcpy(&(ip6->ip6_src), &src_addr, sizeof(struct in6_addr));
memcpy(&(ip6->ip6_dst), &dst_addr, sizeof(struct in6_addr));
// create ICMPv6 header
icmp6 = (struct icmp6_hdr *) (buf + 40); // 40B ~ IPv6 packet size
icmp6->icmp6_type = ICMP6_ECHO_REQUEST;
icmp6->icmp6_code = 0;
icmp6->icmp6_cksum= 0;
icmp6->icmp6_data32[0] = 0;
libnet_do_checksum(l, (u_int8_t *)buf, IPPROTO_ICMPV6, packet_len);
written = libnet_write_raw_ipv6(l, buf, packet_len);
if ( written != packet_len )
perror("Failed to send packet");
libnet_destroy(l);
free(buf);
I tried to find code examples but with no success.
Thank you in advance.
Martin
If you're using C++, then I'd recommend you libtins, a packet crafting a sniffing library. This short snippet does exactly what you want:
#include <tins/tins.h>
using namespace Tins;
void test(const IPv6Address &dst, const IPv6Address &src) {
PacketSender sender;
IPv6 ipv6 = IPv6(dst, src) / ICMPv6();
ipv6.hop_limit(64);
sender.send(ipv6);
}
int main() {
// now use it
test("f0ef:1234::1", "f000::1");
}
You can create it with raw sockets though. I also had to do something similar but couldn't find anything as a reference.
To do it with raw sockets, this link gives you a nice explanation
Related
I'm currently using a Esp32 which presents, in addition to wifi, an ethernet interface.
I'm using the esp-idf v3.3 with FreeRTOS.
To use it I included the "esp_eth.h" library (https://docs.espressif.com/projects/esp-idf/en/release-v3.1/api-reference/ethernet/esp_eth.html#api-reference-phy-lan8720).
I'd like to use both Wifi and ethernet interfaces basing on what I want to do but selecting which one to use, is there a way?
The practical use is to receive a command through the ethernet interface (for example a site to ping), ping the server through the wifi interface and answer back to the ethernet interface the ping result.
How can I select which interface to use (i dont want that the ping is made through the ethernet or that the response go through the wifi).
#edit: i found the method netif_set_default(struct netif * netif), but i dont know if it is the best way to select the interface to use for the specific action(i should swap from one interface to another)
Just get the IP of the Ethernet interface, then bind a socket to that IP address.
struct in_addr iaddr = {0};
#if USE_ANY_IF
// Bind the socket to any address
iaddr.s_addr = htonl(INADDR_ANY);
#else
// bind only to the Ethernet interface
tcpip_adapter_ip_info_t ip_info = {0};
tcpip_adapter_get_ip_info(TCPIP_ADAPTER_IF_ETH, &ip_info);
inet_addr_from_ip4addr(&iaddr, &ip_info.ip);
#endif
Then use it to bind a socket, for example:
static int create_multicast_ipv4_socket(struct in_addr bind_iaddr)
{
struct sockaddr_in saddr = {0};
int sock = -1;
int err = 0;
char addrbuf[32] = {0};
sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
if (sock < 0)
{
ESP_LOGE(V4TAG, "Failed to create socket. Error %d", errno);
return -1;
}
saddr.sin_addr.s_addr = bind_iaddr.s_addr; // what interface IP to bind to. Can be htonl(INADDR_ANY)
saddr.sin_family = PF_INET;
saddr.sin_port = htons(UDP_PORT);
inet_ntoa_r(saddr.sin_addr.s_addr, addrbuf, sizeof(addrbuf) - 1);
ESP_LOGI(TAG, "Binding to interface %s...", addrbuf);
err = bind(sock, (struct sockaddr *)&saddr, sizeof(struct sockaddr_in));
if (err < 0)
{
ESP_LOGE(V4TAG, "Failed to bind socket. Error %d", errno);
goto err;
}
// Assign multicast TTL (set separately from normal interface TTL)
uint8_t ttl = MULTICAST_TTL;
setsockopt(sock, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(uint8_t));
if (err < 0)
{
ESP_LOGE(V4TAG, "Failed to set IP_MULTICAST_TTL. Error %d", errno);
goto err;
}
// All set, socket is configured for sending
return sock;
err:
close(sock);
return -1;
}
I struggle with Intel XL710 card using DPDK to make it compute RSS hash using only SRC IPV4 or DST IPV4 on per port basis.
The card has 4 10GE ports and RSS config is global for them whatever i do. I tried to set SRC/DST IPV4 fields in PCTYPE and the configuration applied last only takes action.
So the behavior i want to achieve.
Let's say i have upstream packet arrived on port 0:
SRC: 10.10.10.1 and DST:10.10.10.2
And reply downstream packet arrived on port 1:
SRC: 10.10.10.2 and DST:10.10.10.1
I want port 0 (which in our case is upstream) on the card to compute RSS hash based on SRC address 10.10.10.1 and for, port 1 (which is downstream) to compute the hash using DST address which in our case also will be 10.10.10.1. So the idea is to distribute packets between RX queues in a way that only SRC/DST address respectively affects this distribution.
I'm not bound specifically to RSS. Whatever tech will do if it allows to achieve this.
The configuration i used:
void setFilter(uint16_t portId, uint32_t value){
//Value = RTE_ETH_FLOW_NONFRAG_IPV4_TCP in that case
struct rte_eth_hash_filter_info info;
uint32_t ftype, idx, offset;
int ret;
if (rte_eth_dev_filter_supported(portId,
RTE_ETH_FILTER_HASH) < 0) {
printf("RTE_ETH_FILTER_HASH not supported on port %d\n",
portId);
return;
}
memset(&info, 0, sizeof(info));
info.info_type = RTE_ETH_HASH_FILTER_GLOBAL_CONFIG;
info.info.global_conf.hash_func =
RTE_ETH_HASH_FUNCTION_DEFAULT;
ftype = value;
idx = ftype / UINT64_BIT;
offset = ftype % UINT64_BIT;
info.info.global_conf.valid_bit_mask[idx] |= (1ULL << offset);
info.info.global_conf.sym_hash_enable_mask[idx] |=
(1ULL << offset);
ret = rte_eth_dev_filter_ctrl(portId, RTE_ETH_FILTER_HASH,
RTE_ETH_FILTER_SET, &info);
if (ret < 0)
printf("Cannot set global hash configurations by port %d\n",
portId);
else
printf("Global hash configurations have been set "
"succcessfully by port %d\n", portId);
}
void setPctypeRss(uint16_t portId, uint16_t fieldIdx) {
/* Note that AVF_FILTER_PCTYPE_NONF_IPV4_TCP is define for
* Virtual Function. Defines are the same for Physical Functions
*/
int ret = -ENOTSUP;
enum rte_pmd_i40e_inset_type inset_type = INSET_HASH;
struct rte_pmd_i40e_inset inset;
ret = rte_pmd_i40e_inset_get(portId, AVF_FILTER_PCTYPE_NONF_IPV4_TCP,
&inset, inset_type);
if (ret) {
printf("Failed to get input set.\n");
return;
}
memset(&inset, 0, sizeof(inset));
ret = rte_pmd_i40e_inset_set(portId, AVF_FILTER_PCTYPE_NONF_IPV4_TCP,
&inset, inset_type);
if (ret) {
printf("Failed to CLEAR input set.\n");
return;
}
else
{
printf("Successfull cleared input set\n");
}
ret = rte_pmd_i40e_inset_get(portId, AVF_FILTER_PCTYPE_NONF_IPV4_TCP,
&inset, inset_type);
if (ret) {
printf("Failed to get input set.\n");
return;
}
ret = rte_pmd_i40e_inset_field_set(&inset.inset, fieldIdx);
if (ret) {
printf("Failed to configure input set field.\n");
return;
}
ret = rte_pmd_i40e_inset_set(portId, AVF_FILTER_PCTYPE_NONF_IPV4_TCP,
&inset, inset_type);
if (ret) {
printf("Failed to set input set.\n");
return;
}
if (ret == -ENOTSUP)
printf("Function not supported\n");
}
IMO it is worth trying a bit simpler solution. We can simply use rte_eth_dev_configure():
https://doc.dpdk.org/api/rte__ethdev_8h.html#a1a7d3a20b102fee222541fda50fd87bd
And just set eth_conf.rss_conf.rss_hf to ETH_RSS_IP as described here:
https://doc.dpdk.org/api/structrte__eth__rss__conf.html#ad70f17882a835e5d4e38c64a9f872fdc
There are few examples in DPDK using this functionality. and most of them work fine ;)
As the title says I have hostname (eg www.example.com) that I want to resolve using specified DNS server. For example in one case I want to use google's IPv4 DNS and in other case google's IPv6 DNS.
I have browsed SO for something like this on iOS, and found questions like this one (Swift - Get device's IP Address), so I am sure it can be done, but I am unclear how?
How can I do this?
EDIT 06/07/2018
#mdeora suggested solution from http://www.software7.com/blog/programmatically-query-specific-dns-servers-on-ios/
This solution works but only if I use IPv4 DNS, for example google's "8.8.8.8". If I try to use IPv6 DNS 2001:4860:4860::8888, i get nothing.
I have managed to change conversion:
void setup_dns_server(res_state res, const char *dns_server)
{
res_ninit(res);
struct in_addr addr;
// int returnValue = inet_aton(dns_server, &addr);
inet_pton(AF_INET6, dns_server, &addr); // for IPv6 conversion
res->nsaddr_list[0].sin_addr = addr;
res->nsaddr_list[0].sin_family = AF_INET;
res->nsaddr_list[0].sin_port = htons(NS_DEFAULTPORT);
res->nscount = 1;
};
But still have trouble with this:
void query_ip(res_state res, const char *host, char ip[])
{
u_char answer[NS_PACKETSZ];//NS_IN6ADDRSZ NS_PACKETSZ
int len = res_nquery(res, host, ns_c_in, ns_t_a, answer, sizeof(answer));
ns_msg handle;
ns_initparse(answer, len, &handle);
if(ns_msg_count(handle, ns_s_an) > 0) {
ns_rr rr;
if(ns_parserr(&handle, ns_s_an, 0, &rr) == 0) {
strcpy(ip, inet_ntoa(*(struct in_addr *)ns_rr_rdata(rr)));
}
}
}
I get -1 for len. From what I gather it seems I need to configure res_state for IPv6.
Here the code from my blogpost, that was already mentioned above, just slightly adapted to use IPv6.
Adapt setup_dns_server
First we could start with the changes to setup_dns_server:
void setup_dns_server(res_state res, const char *dns_server) {
struct in6_addr addr;
inet_pton(AF_INET6, dns_server, &addr);
res->_u._ext.ext->nsaddrs[0].sin6.sin6_addr = addr;
res->_u._ext.ext->nsaddrs[0].sin6.sin6_family = AF_INET6;
res->_u._ext.ext->nsaddrs[0].sin6.sin6_port = htons(NS_DEFAULTPORT);
res->nscount = 1;
}
Add __res_state_ext
This wouldn't compile because of a missing struct __res_state_ext. This structure is unfortunately in a private header file.
But the definition of that one can be take from here:
https://opensource.apple.com/source/libresolv/libresolv-65/res_private.h.auto.html :
struct __res_state_ext {
union res_sockaddr_union nsaddrs[MAXNS];
struct sort_list {
int af;
union {
struct in_addr ina;
struct in6_addr in6a;
} addr, mask;
} sort_list[MAXRESOLVSORT];
char nsuffix[64];
char bsuffix[64];
char nsuffix2[64];
};
The struct can be added e.g. at the top of the file.
Adapt resolveHost
The changes here include the longer buffer for ip (INET6_ADDRSTRLEN). res_ninit moved from setup_dns_server into this method and is matched now with a res_ndestroy.
+ (NSString *)resolveHost:(NSString *)host usingDNSServer:(NSString *)dnsServer {
struct __res_state res;
char ip[INET6_ADDRSTRLEN];
memset(ip, '\0', sizeof(ip));
res_ninit(&res);
setup_dns_server(&res, [dnsServer cStringUsingEncoding:NSASCIIStringEncoding]);
query_ip(&res, [host cStringUsingEncoding:NSUTF8StringEncoding], ip);
res_ndestroy(&res);
return [[NSString alloc] initWithCString:ip encoding:NSASCIIStringEncoding];
}
Retrieving IPv6 addresses
The changes above are already sufficient if you just want to use a IPv6 address for your DNS server. So in query_ip there are no changes necessary if you still want to retrieve the IPv4 addresses.
In case you would like to retrieve IPv6 addresses from the DNS server also, you can do this:
void query_ip(res_state res, const char *host, char ip[]) {
u_char answer[NS_PACKETSZ];
int len = res_nquery(res, host, ns_c_in, ns_t_aaaa, answer, sizeof(answer));
ns_msg handle;
ns_initparse(answer, len, &handle);
if(ns_msg_count(handle, ns_s_an) > 0) {
ns_rr rr;
if(ns_parserr(&handle, ns_s_an, 0, &rr) == 0) {
inet_ntop(AF_INET6, ns_rr_rdata(rr), ip, INET6_ADDRSTRLEN);
}
}
}
Please note: we use here ns_t_aaaa to get AAAA resource records (quad-A record), because in DNS this specifies the mapping between IPv6 address and hostname. For many hosts, there is no such quad-A record, meaning you can just reach them via IPv4.
Call
You would call it e.g. like so:
NSString *resolved = [ResolveUtil resolveHost:#"www.google.com" usingDNSServer:#"2001:4860:4860::8888"];
NSLog(#"%#", resolved);
The result would the look like this:
Disclaimer
These are just simple example calls, that demonstrate the basic usage of the functions. There is no error handling.
You can do this using below swift code -
import Foundation
let task = Process()
task.launchPath = "/usr/bin/env"
task.arguments = ["dig", "#8.8.8.8", "google.com"]
let pipe = Pipe()
task.standardOutput = pipe
task.launch()
let data = pipe.fileHandleForReading.readDataToEndOfFile()
let output = NSString(data: data, encoding: String.Encoding.utf8.rawValue)
print(output!)
In the above code use the DNS server of your choice by replacing 8.8.8.8
For Objective-C iOS refer below link -
https://www.software7.com/blog/programmatically-query-specific-dns-servers-on-ios/
Below is the revised code for setting up dns -
void setup_dns_server(res_state res, const char *dns_server)
{
res_ninit(res);
struct in_addr6 addr;
// int returnValue = inet_aton(dns_server, &addr);
inet_pton(AF_INET6, dns_server, &addr); // for IPv6 conversion
res->nsaddr_list[0].sin_addr = addr;
res->nsaddr_list[0].sin_family = AF_INET6;
res->nsaddr_list[0].sin_port = htons(NS_DEFAULTPORT);
res->nscount = 1;
};
And the query code -
void query_ip(res_state res, const char *host, char ip[])
{
u_char answer[NS_PACKETSZ];//NS_IN6ADDRSZ NS_PACKETSZ
int len = res_nquery(res, host, ns_c_in, ns_t_a, answer, sizeof(answer));
ns_msg handle;
ns_initparse(answer, len, &handle);
if(ns_msg_count(handle, ns_s_an) > 0) {
ns_rr rr;
if(ns_parserr(&handle, ns_s_an, 0, &rr) == 0) {
strcpy(ip, inet_ntoa(*(struct in_addr6 *)ns_rr_rdata(rr)));
}
}
}
PS - I have not been able to test it, but it should work for ipv6 dns.
I am writing a plugins subsystem and one of the ideas is to iterate through a dylib (or at least current global scope) exported functions. I know there are other ways, just really want to give this one a try.
What I am wondering, is there a way to get a list of functions exported by a dylib or available in global scope through OS X and iOS API?
Thanks in advance!
You can use a command 'nm' for getting an information from a dynamic library.
See additionally system manual for this command on Mac.
If you are looking to do that from code, you could use this method.
std::vector<std::string> load_mach_o(std::string file_name)
{
/*
Parse the Mach-O structure to find all the exported symbols
Mach-O structure:
mach_header_64
cmd
...
cmd
data
...
data
*/
std::vector<std::string> methods;
off_t offset = sizeof(struct mach_header_64);
BYTE * bytes = load_bytes(file_name.c_str());
if (bytes == NULL)
{
return methods;
}
struct mach_header_64 *header = (struct mach_header_64 *)bytes;
//Get the load commands
struct load_command *cmd = (struct load_command *)(bytes + offset);
for (uint32_t i = 0U; i < header->ncmds; i++)
{
if (cmd->cmd == LC_SYMTAB)
{
struct symtab_command * symtab = (struct symtab_command *)cmd;
off_t string_start = 0;
const char* strings = (const char *)(bytes + symtab->stroff + 1);
for (uint32_t i = 0 ; i < symtab->strsize ; i++)
{
if (strings[i] == '\0')
{
i++;
size_t size = sizeof(char) * (i - string_start);
if (size == 1)
{
string_start = i+1;
continue;
}
methods.push_back(std::string((const char *)(strings + string_start)));
string_start = i+1;
}
}
}
offset += cmd->cmdsize;
//load next command
cmd = (struct load_command *)(bytes + offset);
}
free(bytes);
return methods;
}
This function read the file and parses the structure till mach-O strings section, then, parses each string and store it in a vector containing all the exposed functions.
Best regards.
I'm trying to implement simple traceroute for the iOS. Everything seems to work fine, except that somehow when I run my application on simulator or on the device it finds only a few (6-7) first routers on the way when the CLI traceroute finds all 14 routers.
const char *c = "www.gmail.com";
struct hostent *host_entry = gethostbyname(c);
char *ip_addr;
ip_addr = inet_ntoa(*((struct in_addr *)host_entry->h_addr_list[0]));
struct sockaddr_in destination, fromAddr;
int recv_sock;
int send_sock;
// Creting Sockets///
if ((recv_sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP)) <
0) // using UDP socket.
{
NSLog(#"Could not cretae recv_sock.\n");
}
if ((send_sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
NSLog(#"Could not cretae send_sock.\n");
}
memset(&destination, 0, sizeof(destination));
destination.sin_family = AF_INET;
destination.sin_addr.s_addr = inet_addr(ip_addr);
destination.sin_port = htons(80);
struct timeval tv;
tv.tv_sec = 0;
tv.tv_usec = 10000;
setsockopt(recv_sock, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv,
sizeof(struct timeval));
char *cmsg = "GET / HTTP/1.1\r\n\r\n";
int max_ttl = 20;
int num_attempts = 5;
socklen_t n = sizeof(fromAddr);
char buf[100];
for (int ttl = 1; ttl <= max_ttl; ttl++) {
memset(&fromAddr, 0, sizeof(fromAddr));
if (setsockopt(send_sock, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)) < 0)
NSLog(#"error in setsockopt\n");
for (int try = 0; try < num_attempts; try ++) {
if (sendto(send_sock, cmsg, sizeof(cmsg), 0,
(struct sockaddr *)&destination,
sizeof(destination)) != sizeof(cmsg))
NSLog(#"error in send to...\n#");
int res = 0;
if ((res = recvfrom(recv_sock, buf, 100, 0, (struct sockaddr *)&fromAddr,
&n)) < 0) {
NSLog(#"an error: %s; recvfrom returned %d\n", strerror(errno), res);
} else {
char display[16] = {0};
inet_ntop(AF_INET, &fromAddr.sin_addr.s_addr, display, sizeof(display));
NSLog(#"Received packet from%s for TTL=%d\n", display, ttl);
break;
}
}
}
I have tried to bind the send socket but have same results and I can't use Sock_raw on iOS. I tried to run it on my mac and got same results. The error I get is "Resource temporarily unavailable;" for the recvfrom(). Why is that? How can I fix it?
The EAGAIN error ( producing "Resource temporarily unavailable;" string) could be raised by the timeout of the receiving socket.
Since you set just 10000 microseconds as read timeout (that's really short IMHO) with this line...
struct timeval tv;
tv.tv_sec = 0;
tv.tv_usec = 10000;
setsockopt(recv_sock, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv,sizeof(struct timeval));
... it's possibile that the longer the way (i mean the number of router you have to pass through), the more chance you have to incour in this situation.
Try to raise timeout value and let us know if it got better.
EDIT
I tried the source code under linux and i noticed two kind of problems.
As mentioned above: Timeouts
Problem with the 80 port
I just raised the timeout and used a port different than 80 (in my case i sent udp message to 40000 port) and i got back all the hops just like traceroute command.
I'm not sure why this behaviour occour. Maybe some kind of "possible malicious packet alarm" gets triggered by the router that discards it
FURTHER EDIT
Look at this link: man traceroute
In the List Of Available Methods section you can find many ways to achieve what you need. Your method is similar to the default one, stating:
Probe packets are udp datagrams with so-called "unlikely" destination ports. The "unlikely" port of the first probe is 33434, then for each next probe it is incremented by one. Since the ports are expected to be unused, the destination host normally returns "icmp unreach port" as a final response. (Nobody knows what happens when some application listens for such ports, though).
So, if you need to full emulate the behaviour of the common Linux traceroute you have to increase by 1 the destination port, everytime the TTL increase (or everytime you can't get a response IMHO)
MAYBE, sometimes your command doesn't work on certain ports because the router is listening to the latter (as suggested by Linux manual and underlined in bold by me).