Kernel+LibC+UserspaceEmulator: Mostly add recvmsg(), sendmsg()

The implementation only supports a single iovec for now.
Some might say having more than one iovec is the main point of
recvmsg() and sendmsg(), but I'm interested in the control message
bits.

2 files changed, 44 insertions, 6 deletions

diff --git a/Libraries/LibC/sys/socket.cpp b/Libraries/LibC/sys/socket.cpp
index f6584bcb85..55c754b32e 100644
--- a/Libraries/LibC/sys/socket.cpp
+++ b/Libraries/LibC/sys/socket.cpp
@@ -28,7 +28,9 @@
 #include <Kernel/API/Syscall.h>
 #include <errno.h>
 #include <stdio.h>
+#include <string.h>
 #include <sys/socket.h>
+#include <sys/uio.h>
 
 extern "C" {
 
@@ -68,25 +70,48 @@ int shutdown(int sockfd, int how)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
-ssize_t sendto(int sockfd, const void* data, size_t data_length, int flags, const struct sockaddr* addr, socklen_t addr_length)
+ssize_t sendmsg(int sockfd, const struct msghdr* msg, int flags)
 {
-    Syscall::SC_sendto_params params { sockfd, { data, data_length }, flags, addr, addr_length };
-    int rc = syscall(SC_sendto, &params);
+    int rc = syscall(SC_sendmsg, sockfd, msg, flags);
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
+ssize_t sendto(int sockfd, const void* data, size_t data_length, int flags, const struct sockaddr* addr, socklen_t addr_length)
+{
+    iovec iov = { const_cast<void*>(data), data_length };
+    msghdr msg = { const_cast<struct sockaddr*>(addr), addr_length, &iov, 1, nullptr, 0, 0 };
+    return sendmsg(sockfd, &msg, flags);
+}
+
 ssize_t send(int sockfd, const void* data, size_t data_length, int flags)
 {
     return sendto(sockfd, data, data_length, flags, nullptr, 0);
 }
 
-ssize_t recvfrom(int sockfd, void* buffer, size_t buffer_length, int flags, struct sockaddr* addr, socklen_t* addr_length)
+ssize_t recvmsg(int sockfd, struct msghdr* msg, int flags)
 {
-    Syscall::SC_recvfrom_params params { sockfd, { buffer, buffer_length }, flags, addr, addr_length };
-    int rc = syscall(SC_recvfrom, &params);
+    int rc = syscall(SC_recvmsg, sockfd, msg, flags);
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
+ssize_t recvfrom(int sockfd, void* buffer, size_t buffer_length, int flags, struct sockaddr* addr, socklen_t* addr_length)
+{
+    if (!addr_length && addr) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    sockaddr_storage internal_addr;
+    iovec iov = { buffer, buffer_length };
+    msghdr msg = { addr ? &internal_addr : nullptr, addr ? sizeof(internal_addr) : 0, &iov, 1, nullptr, 0, 0 };
+    ssize_t rc = recvmsg(sockfd, &msg, flags);
+    if (rc >= 0 && addr) {
+        memcpy(addr, &internal_addr, min(*addr_length, msg.msg_namelen));
+        *addr_length = msg.msg_namelen;
+    }
+    return rc;
+}
+
 ssize_t recv(int sockfd, void* buffer, size_t buffer_length, int flags)
 {
     return recvfrom(sockfd, buffer, buffer_length, flags, nullptr, nullptr);
diff --git a/Libraries/LibC/sys/socket.h b/Libraries/LibC/sys/socket.h
index f14e1d7005..898269fb8e 100644
--- a/Libraries/LibC/sys/socket.h
+++ b/Libraries/LibC/sys/socket.h
@@ -61,10 +61,21 @@ __BEGIN_DECLS
 #define IPPROTO_TCP 6
 #define IPPROTO_UDP 17
 
+#define MSG_TRUNC 0x1
 #define MSG_DONTWAIT 0x40
 
 typedef uint16_t sa_family_t;
 
+struct msghdr {
+    void* msg_name;
+    socklen_t msg_namelen;
+    struct iovec* msg_iov;
+    int msg_iovlen;
+    void* msg_control;
+    socklen_t msg_controllen;
+    int msg_flags;
+};
+
 struct sockaddr {
     sa_family_t sa_family;
     char sa_data[14];
@@ -102,8 +113,10 @@ int accept(int sockfd, struct sockaddr*, socklen_t*);
 int connect(int sockfd, const struct sockaddr*, socklen_t);
 int shutdown(int sockfd, int how);
 ssize_t send(int sockfd, const void*, size_t, int flags);
+ssize_t sendmsg(int sockfd, const struct msghdr*, int flags);
 ssize_t sendto(int sockfd, const void*, size_t, int flags, const struct sockaddr*, socklen_t);
 ssize_t recv(int sockfd, void*, size_t, int flags);
+ssize_t recvmsg(int sockfd, struct msghdr*, int flags);
 ssize_t recvfrom(int sockfd, void*, size_t, int flags, struct sockaddr*, socklen_t*);
 int getsockopt(int sockfd, int level, int option, void*, socklen_t*);
 int setsockopt(int sockfd, int level, int option, const void*, socklen_t);