Working with the Unix OS

Interprocess Communication
Server
socket()
|
bind()
|
recvfrom()
| Client
blocks until connection from client
socket()
| |
| connect()
| |
process request| |
| |
sendto() recvfrom()
! Socket system calls connectionless protocol
Unix Domain Protocols
Provide a feature that is not currently provided by any other protocol family: the ability to pass access rights from
one process to another.
The name space used by unix domain protocols consists of pathnames, for example:
{ unixstr, 0 /tmp/log.1528, 0, /dev/logfile }
unixstr unix stream connection oriented
0 local address
/tmp/log.1528 local process
0 remote address
0 /dev/logfile remote process
Socket Addresses
/* defined in */
struct sockaddr {
u_short sa_family; /* address family: AF_xxx */
char sa_data[14];} /* protocol specific addr */
/* defined in */
struct in_addr {
u_long s_addr; /* 32-bit netid/hostid */
}; /* network byte ordered */
struct sockaddr_in {
short sin_family; /* AF_INET * /
u_short sin-port; /* 16-bit port number */
struct in_addr sin_addr; /* netid/hostid */
char sin_zero[8]; /* unused */
};
/* defined in */
struct sockaddr_un {
short sun_family; /* AF_UNIX */
char sun_path[108]; /* pathname */
};
Socket address structures struct sockaddr_in struct sockaddr_un
family
family
2 byte port
4 byte net ID, host ID
pathname
(unused)
(upto 108 bytes)
struct sockaddr_in serv_addr;
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