The document discusses three types of local sockets in Android native code: abstract, reserved, and filesystem. It provides code examples of creating server and client sockets for each type. Abstract sockets use names in the abstract namespace like "android:debuggerd". Reserved sockets use names in the /dev/socket directory like "gps". Filesystem sockets specify a normal filesystem path as the name. The code shows creating, connecting, reading and writing data to sockets of each type.

1. Android Local Sockets In Native Code
T.V.R.Prasad

2. Contents
● Types of Sockets
● ANDROID_SOCKET_NAMESPACE_ABSTRACT
● ANDROID_SOCKET_NAMESPACE_RESERVED
● ANDROID_SOCKET_NAMESPACE_FILESYSTEM

3. Types Of Sockets
● ANDROID_SOCKET_NAMESPACE_ABSTRACT
A socket in the Linux abstract namespace.
● ANDROID_SOCKET_NAMESPACE_RESERVED
A socket in the Android reserved namespace in
/dev/socket.
● ANDROID_SOCKET_NAMESPACE_FILESYSTEM
A socket named with a normal filesystem path.
● The code indicates the presence of filesystem
entries for the RESERVED and FILESYSTEM type of
sockets.

4. ANDROID_SOCKET_NAMESPACE_ABSTRACT
/* Server Example */
int serverFd; /* File descriptor of Server Socket */
int clientFd; /* File descriptor of Client Socket */
int clen; /* Size of the peer address */
serverFd = socket_local_server("android:debuggerd",
ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
if(serverFd < 0) return ­1;
struct sockaddr addr;
socklen_t alen = sizeof(addr);
/* Wait for connection request from client */
clientFd = accept(s, &addr, &alen);
/* Read and write data from client socket */
readLen = read(clientFd, data, dataLen);
writeLen = write(clientFd, status, sizeof(status));

5. ANDROID_SOCKET_NAMESPACE_ABSTRACT
/* Client Example */
int socketFd; /* File descriptor of Server Socket */
socketFd = socket_local_client("android:debuggerd",
ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
if(socketFd >= 0) {
/* Read and write data to the server */
readLen = read(socketFd, data, dataLen);
writeLen = write(socketFd, status, sizeof(status));
}
/* Close the server socket once done */
close(socketFd);

6. ANDROID_SOCKET_NAMESPACE_RESERVED
/* Server Example */
int serverFd; /* File descriptor of Server Socket */
int clientFd; /* File descriptor of Client Socket */
int clen; /* Size of the peer address */
serverFd = socket_local_server("gps",
ANDROID_SOCKET_NAMESPACE_RESERVED, SOCK_SEQPACKET);
/* Wait for connection request from client */
clientFd = accept(serverFd, 0, &clen);
/* Read data from client socket */
readLen = read(clientFd, data, dataLen);
/* Write data to client socket */
writeLen = write(clientFd, status, sizeof(status));

7. ANDROID_SOCKET_NAMESPACE_RESERVED
/* Client Example */
int socketFd; /* File descriptor of Socket */
/*Create a client socket and connect to the address
with the name gps in the reserved socket namespace */
socketFd = socket_local_client("gps",
ANDROID_SOCKET_NAMESPACE_RESERVED, SOCK_SEQPACKET);
/*
socketFd less than 0 indicates failure to connect to
the server,return Error;
*/
if(socketFd < 0) {
return Error;
}
/* Read and write data to the server */
readLen = read(socketFd, data, dataLen);
writeLen = write(socketFd, status, sizeof(status));

8. ANDROID_SOCKET_NAMESPACE_FILESYSTEM
/* Server Example */
/* File descriptor of Server Socket and Client sockets*/
int serverFd,clientFd;
int connect(const char *name)
{
serverFd = socket_local_server(name,
ANDROID_SOCKET_NAMESPACE_FILESYSTEM, SOCK_STREAM);
return serverFd;
}
/* Wait for connection request from client and after
accepting the connection read and write data from
client socket */
readLen = read(clientFd, data, dataLen);

9. ANDROID_SOCKET_NAMESPACE_FILESYSTEM
/* Client Example */
int socketFd; /* File descriptor of Server Socket */
int connect(const char *name)
{
socketFd = socket_local_client(name,
ANDROID_SOCKET_NAMESPACE_FILESYSTEM, SOCK_STREAM);
return socketFd;
}
if(socketFd >= 0) {
/* Read and write data to the server */
readLen = read(socketFd, data, dataLen);
/* Close the server socket once done */
close(socketFd);

10. Thank You