1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#if defined(__sun__)
# include <sys/filio.h> /* The official way to get FIONREAD in SunOS;
others seem to get it from <sys/ioctl.h> */
#endif
#include <sys/socket.h>
#include "relay.h"
#define Export
#define MIN(a,b) ((a) < (b) ? (a) : (b))
#define MAX(a,b) ((a) > (b) ? (a) : (b))
/*
* Estimate how many bytes are available for reading on a file descriptor.
*/
static long
available_bytes(int fd)
{
long nbytes;
struct stat sb;
off_t pos;
/*
* Some Unices don't support the FIONREAD ioctl on regular files.
* They don't even return an error, but says there are zero bytes
* to be read. We then try to fstat() the file descriptor to see
* how big the file is, and try to determine at what offset the
* file pointer is at now. That doesn't work always either...
*/
if (ioctl(fd, FIONREAD, &nbytes) < 0 || nbytes == 0)
{
if (fstat(fd, &sb) < 0)
return -1;
errno = 0;
pos = lseek(fd, 0, SEEK_CUR);
if ((pos < 0 && errno != 0) || !S_ISREG(sb.st_mode))
pos = 0;
nbytes = sb.st_size - pos;
}
return nbytes;
}
/*
* Wait for data to arrive on any of the source file descriptors in
* RELAYS, read all available data, and write to respective dest
* file descriptors. TIMEOUT is the maximum time to wait, or a nil
* pointer to never time out. For each read() done, the function
* CALLBACK is called. Note that CALLBACK may be called more than
* once for each file descriptor if much data is available.
* NRELAYS is the number of elements in RELAYS.
*
* If the 'readerror' field is non-zero for a relay, no read will be
* attempted from the source file descriptor of that relay.
* If the 'writerror' field is non-zero for a relay, no write will be
* attempted to the dest file descriptor of that relay, but the source
* descriptor will still be drained from any available data.
*
* If end-of-file is reached on the source of a relay, the corresponding
* destination will be shutdown() for writing, thus causing the other
* end to see a end-of-file.
* If a write error occurs on the destination of a relay, the source
* of that relay will be shutdown() for reading, causing the other end
* to get errors when trying to write more data to us.
* Note that the SIGPIPE signal should be ignored, or possibly caught,
* by the caller, or the process will die when a receiver closes its
* end for receiving.
*
* Returns the number of file descriptor read from, or negative on error.
*/
Export int
relay_once(struct relay * relays,
int nrelays,
struct timeval * timeout,
int (*callback)(struct relay*, char*, size_t)
)
{
int maxfd;
fd_set readset;
int i;
int nfds;
int nerrors = 0;
FD_ZERO(&readset);
maxfd = 0;
for (i = nrelays - 1 ; i >= 0 ; i--)
{
if (!relays[i].readerror) {
FD_SET(relays[i].source, &readset);
if (relays[i].source > maxfd)
maxfd = relays[i].source;
}
}
nfds = select(maxfd+1, &readset, (fd_set*)NULL, (fd_set*)NULL, timeout);
if (nfds <= 0) {
if (errno != EINTR)
return nfds;
else
return 0;
}
for (i = nrelays - 1 ; i >= 0 ; i--)
{
if (FD_ISSET(relays[i].source, &readset))
{
long unread = available_bytes(relays[i].source);
do
{
char buffer[8192];
int bytes_read = read(relays[i].source, buffer, sizeof buffer);
if (bytes_read < 0) {
relays[i].readerror = errno;
nerrors++;
break;
}
unread -= bytes_read;
if (bytes_read == 0) {
relays[i].readerror = -1;
shutdown(relays[i].dest, 1);
nerrors++;
}
if (callback)
(*callback)(&relays[i], buffer, bytes_read);
if (!relays[i].writeerror && bytes_read > 0) {
int written = write(relays[i].dest, buffer, bytes_read);
if (written < 0) {
relays[i].writeerror = errno;
shutdown(relays[i].source, 0);
nerrors++;
break;
}
}
} while (unread > 0);
}
}
return nerrors ? -nerrors : nfds;
}
/*
* Call relay_once() until end-of-file has been reached on all sources.
* No time limit.
*/
Export int
relay_all(struct relay * relaylist,
int nrelays,
int (*callback)(struct relay*, char*, size_t))
{
int nclosed = 0;
do
{
int status = relay_once(relaylist, nrelays, NULL, callback);
if (status < 0)
nclosed += -status;
} while (nclosed < nrelays);
return 0;
}
|
