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More work on IPv4 sockets and /bin/ping.

It's now actually possible to ping other hosts on the network! :^)
I've switched the "run" script over to starting QEMU with user networking
since that works better for my testing needs right now.
This commit is contained in:
Andreas Kling 2019-03-13 03:26:01 +01:00
parent ce7c302933
commit cf250e1245
7 changed files with 125 additions and 38 deletions

View file

@ -4,23 +4,32 @@
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <Kernel/NetworkOrdered.h>
#include <time.h>
NetworkOrdered<word> internet_checksum(const void* ptr, size_t count)
uint16_t internet_checksum(const void* ptr, size_t count)
{
dword checksum = 0;
auto* w = (const word*)ptr;
uint32_t checksum = 0;
auto* w = (const uint16_t*)ptr;
while (count > 1) {
checksum += convert_between_host_and_network(*w++);
checksum += ntohs(*w++);
if (checksum & 0x80000000)
checksum = (checksum & 0xffff) | (checksum >> 16);
count -= 2;
}
while (checksum >> 16)
checksum = (checksum & 0xffff) + (checksum >> 16);
return ~checksum & 0xffff;
return htons(~checksum);
}
inline void timersub(struct timeval* a, struct timeval* b, struct timeval* result)
{
result->tv_sec = a->tv_sec - b->tv_sec;
result->tv_usec = a->tv_usec - b->tv_usec;
if (result->tv_usec < 0) {
--result->tv_sec;
result->tv_usec += 1000000;
}
}
int main(int argc, char** argv)
{
@ -30,42 +39,82 @@ int main(int argc, char** argv)
return 1;
}
const char* addr_str = "192.168.5.1";
if (argc > 1)
addr_str = argv[1];
pid_t pid = getpid();
sockaddr_in peer_address;
memset(&peer_address, 0, sizeof(peer_address));
peer_address.sin_family = AF_INET;
peer_address.sin_port = 0;
peer_address.sin_addr.s_addr = 0x0105a8c0; // 192.168.5.1
int rc = inet_pton(AF_INET, addr_str, &peer_address.sin_addr);
struct PingPacket {
struct icmphdr header;
char msg[64 - sizeof(struct icmphdr)];
};
PingPacket ping_packet;
PingPacket pong_packet;
memset(&ping_packet, 0, sizeof(PingPacket));
uint16_t seq = 1;
ping_packet.header.type = 8; // Echo request
ping_packet.header.code = 0;
ping_packet.header.un.echo.id = htons(getpid());
ping_packet.header.un.echo.sequence = htons(1);
strcpy(ping_packet.msg, "Hello there!\n");
for (;;) {
PingPacket ping_packet;
PingPacket pong_packet;
memset(&ping_packet, 0, sizeof(PingPacket));
ping_packet.header.checksum = htons(internet_checksum(&ping_packet, sizeof(PingPacket)));
ping_packet.header.type = 8; // Echo request
ping_packet.header.code = 0;
ping_packet.header.un.echo.id = htons(pid);
ping_packet.header.un.echo.sequence = htons(seq++);
strcpy(ping_packet.msg, "Hello there!\n");
int rc = sendto(fd, &ping_packet, sizeof(PingPacket), 0, (const struct sockaddr*)&peer_address, sizeof(sockaddr_in));
if (rc < 0) {
perror("sendto");
return 1;
ping_packet.header.checksum = internet_checksum(&ping_packet, sizeof(PingPacket));
struct timeval tv_send;
gettimeofday(&tv_send, nullptr);
rc = sendto(fd, &ping_packet, sizeof(PingPacket), 0, (const struct sockaddr*)&peer_address, sizeof(sockaddr_in));
if (rc < 0) {
perror("sendto");
return 1;
}
for (;;) {
rc = recvfrom(fd, &pong_packet, sizeof(PingPacket), 0, (const struct sockaddr*)&peer_address, sizeof(sockaddr_in));
if (rc < 0) {
perror("recvfrom");
return 1;
}
if (pong_packet.header.type != 0)
continue;
if (pong_packet.header.code != 0)
continue;
if (ntohs(pong_packet.header.un.echo.id) != pid)
continue;
struct timeval tv_receive;
gettimeofday(&tv_receive, nullptr);
struct timeval tv_diff;
timersub(&tv_receive, &tv_send, &tv_diff);
int ms = tv_diff.tv_sec * 1000 + tv_diff.tv_usec / 1000;
char addr_buf[64];
printf("Pong from %s: id=%u, seq=%u, time=%dms\n",
inet_ntop(AF_INET, &peer_address.sin_addr, addr_buf, sizeof(addr_buf)),
ntohs(pong_packet.header.un.echo.id),
ntohs(pong_packet.header.un.echo.sequence),
ms
);
break;
}
sleep(1);
}
rc = recvfrom(fd, &pong_packet, sizeof(PingPacket), 0, (const struct sockaddr*)&peer_address, sizeof(sockaddr_in));
if (rc < 0) {
perror("recvfrom");
return 1;
}
printf("received %p (%d)\n", &pong_packet, rc);
return 0;
}