Kernel: Expose source information of incoming UDP packets

6 files changed, 99 insertions, 20 deletions

diff --git a/network/ipv4.c b/network/ipv4.c
index 27b38ec..e7ef2c2 100644
--- a/network/ipv4.c
+++ b/network/ipv4.c
@@ -2,6 +2,7 @@
 #include <network/bytes.h>
 #include <network/ipv4.h>
 #include <network/udp.h>
+#include <string.h>
 
 void handle_ipv4(const uint8_t *payload, uint32_t packet_length) {
   assert(packet_length > 4);
@@ -15,10 +16,13 @@ void handle_ipv4(const uint8_t *payload, uint32_t packet_length) {
   // Make sure the ipv4 header is not trying to get uninitalized memory
   assert(ipv4_total_length <= packet_length);
 
+  uint8_t src_ip[4];
+  memcpy(src_ip, payload + 12, sizeof(uint8_t[4]));
+
   uint8_t protocol = *(payload + 9);
   switch (protocol) {
   case 0x11:
-    handle_udp(payload + 20, ipv4_total_length - 20);
+    handle_udp(src_ip, payload + 20, ipv4_total_length - 20);
     break;
   default:
     kprintf("Protocol given in IPv4 header not handeld: %x\n", protocol);
diff --git a/network/udp.c b/network/udp.c
index fb8ba44..29f17e1 100644
--- a/network/udp.c
+++ b/network/udp.c
@@ -3,24 +3,47 @@
 #include <network/udp.h>
 #include <socket.h>
 
-void handle_udp(const uint8_t *payload, uint32_t packet_length) {
+void handle_udp(uint8_t src_ip[4], const uint8_t *payload,
+                uint32_t packet_length) {
   assert(packet_length >= 8);
-  uint16_t source_port = ntohs(*(uint16_t *)payload);
-  uint16_t dst_port = ntohs(*(uint16_t *)(payload + 2));
-  uint16_t length = ntohs(*(uint16_t *)(payload + 4));
-  assert(length == packet_length);
-  kprintf("source_port: %d\n", source_port);
-  kprintf("dst_port: %d\n", dst_port);
-  uint32_t data_length = length - 8;
+  // n_.* means network format(big endian)
+  // h_.* means host format((probably) little endian)
+  uint16_t n_source_port = *(uint16_t *)payload;
+  uint16_t h_source_port = ntohs(n_source_port);
+  uint16_t h_dst_port = ntohs(*(uint16_t *)(payload + 2));
+  uint16_t h_length = ntohs(*(uint16_t *)(payload + 4));
+  assert(h_length == packet_length);
+  kprintf("source_port: %d\n", h_source_port);
+  kprintf("dst_port: %d\n", h_dst_port);
+  uint16_t data_length = h_length - 8;
   const uint8_t *data = payload + 8;
 
   // Find the open port
-  OPEN_INET_SOCKET *in_s = find_open_udp_port(htons(dst_port));
+  OPEN_INET_SOCKET *in_s = find_open_udp_port(htons(h_dst_port));
   assert(in_s);
   SOCKET *s = in_s->s;
   vfs_fd_t *fifo_file = s->ptr_socket_fd;
+
+  // Write the sockaddr struct such that it can later be
+  // given to userland if asked.
+  struct sockaddr_in /*{
+    sa_family_t sin_family;
+    union {
+      uint32_t s_addr;
+    } sin_addr;
+    uint16_t sin_port;
+  }*/ in;
+  in.sin_family = AF_INET;
+  memcpy(&in.sin_addr.s_addr, src_ip, sizeof(uint32_t));
+  in.sin_port = n_source_port;
+  socklen_t sock_length = sizeof(struct sockaddr_in);
+
+  raw_vfs_pwrite(fifo_file, &sock_length, sizeof(sock_length), 0);
+  raw_vfs_pwrite(fifo_file, &in, sizeof(in), 0);
+
+  // Write the UDP payload length(not including header)
+  raw_vfs_pwrite(fifo_file, &data_length, sizeof(uint16_t), 0);
+
+  // Write the UDP payload
   raw_vfs_pwrite(fifo_file, (char *)data, data_length, 0);
-  for (uint32_t i = 0; i < data_length; i++) {
-    kprintf("%c", data[i]);
-  }
 }
diff --git a/network/udp.h b/network/udp.h
index c6ac753..8278b87 100644
--- a/network/udp.h
+++ b/network/udp.h
@@ -1,3 +1,3 @@
 #include <stdint.h>
 
-void handle_udp(const uint8_t *payload, uint32_t packet_length);
+void handle_udp(uint8_t src_ip[4], const uint8_t *payload, uint32_t packet_length);
diff --git a/scalls/recvfrom.c b/scalls/recvfrom.c
index 0e37153..1770fa1 100644
--- a/scalls/recvfrom.c
+++ b/scalls/recvfrom.c
@@ -1,15 +1,59 @@
+#include <assert.h>
 #include <fs/vfs.h>
+#include <math.h>
 #include <poll.h>
 #include <scalls/recvfrom.h>
 
-size_t syscall_recvfrom(int socket, void *buffer, size_t length, int flags,
-                        struct sockaddr *address, socklen_t *address_len) {
+size_t syscall_recvfrom(
+    int socket, void *buffer, size_t length, int flags,
+    struct two_args
+        *extra_args /*struct sockaddr *address, socklen_t *address_len*/) {
+
+  struct sockaddr *address = (struct sockaddr *)extra_args->a;
+  socklen_t *address_len = (socklen_t *)extra_args->b;
+  kprintf("address: %x\n", address);
+  kprintf("address_len: %x\n", address_len);
+
   if (flags & MSG_WAITALL) {
     struct pollfd fds[1];
     fds[0].fd = socket;
     fds[0].events = POLLIN;
     poll(fds, 1, 0);
   }
-  kprintf("got event\n");
-  return vfs_pread(socket, buffer, length, 0);
+
+  uint16_t data_length;
+  socklen_t tmp_socklen;
+  vfs_pread(socket, &tmp_socklen, sizeof(socklen_t), 0);
+  if (address_len)
+    *address_len = tmp_socklen;
+  if (address) {
+    vfs_pread(socket, address, tmp_socklen, 0);
+  } else {
+    // We still have to throwaway the data.
+    char devnull[100];
+    for (; tmp_socklen;) {
+      int rc = vfs_pread(socket, devnull, min(tmp_socklen, 100), 0);
+      assert(rc >= 0);
+      tmp_socklen -= rc;
+    }
+  }
+
+  vfs_pread(socket, &data_length, sizeof(data_length), 0);
+  // If it is reading less than the packet length that could cause
+  // problems as the next read will not be put at a new header. Luckily
+  // it seems as if other UNIX systems can discard the rest of the
+  // packet if not read.
+
+  // Read in the data requested
+  int read_len = min(length, data_length);
+  int rc = vfs_pread(socket, buffer, read_len, 0);
+  // Discard the rest of the packet
+  int rest = data_length - read_len;
+  char devnull[100];
+  for (; rest;) {
+    int rc = vfs_pread(socket, devnull, 100, 0);
+    assert(rc >= 0);
+    rest -= rc;
+  }
+  return rc;
 }
diff --git a/scalls/recvfrom.h b/scalls/recvfrom.h
index 9897899..d81a1e0 100644
--- a/scalls/recvfrom.h
+++ b/scalls/recvfrom.h
@@ -1,4 +1,11 @@
 #include <socket.h>
 
-size_t syscall_recvfrom(int socket, void *buffer, size_t length, int flags,
-                         struct sockaddr *address, socklen_t *address_len);
+struct two_args {
+  uint32_t a;
+  uint32_t b;
+};
+
+size_t syscall_recvfrom(
+    int socket, void *buffer, size_t length, int flags,
+    struct two_args
+        *extra_args /*struct sockaddr *address, socklen_t *address_len*/);
diff --git a/userland/libc/include/socket.h b/userland/libc/include/socket.h
index c4a3e73..2bf6345 100644
--- a/userland/libc/include/socket.h
+++ b/userland/libc/include/socket.h
@@ -40,6 +40,7 @@ struct sockaddr_in {
   sa_family_t sin_family;
   union {
     uint32_t s_addr;
+    uint8_t a[4];
   } sin_addr;
   uint16_t sin_port;
 };