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/*
* dgrambuf.c - C datagrams buffer.
*
* Copyright 2016 by Ludovic Pouzenc <ludovic@pouzenc.fr>
*/
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include "dgrambuf.h"
#include <sys/socket.h> /* recvmmsg() _GNU_SOURCE */
#include <stdlib.h> /* calloc(), free(), qsort() */
#include <stdio.h> /* perror() */
#include <string.h> /* memset() */
#include <sys/uio.h> /* writev() */
struct uint_pair {
unsigned int index;
unsigned int value;
};
struct dgrambuf_t {
size_t dgram_count;
size_t dgram_max_size;
size_t dgram_header_size;
struct iovec *recv_iovecs;
struct iovec *write_iovecs;
struct mmsghdr *msgs;
unsigned int win_base;
unsigned int *dgram_seq_numbers; /* Stores the decoded datagram sequence number for each dgram slot of buf */
unsigned int *dgram_len;
struct uint_pair *dgram_ordered_seq_numbers;
void *buf;
unsigned int (*validate_func)(unsigned int, void *);
//TODO pthread_mutex_lock
};
int _compare_uint_pair(const void *pa, const void *pb);
void dgrambuf_set_validate_func(dgrambuf_t dbuf, unsigned int (*func)(unsigned int, void *) ) {
dbuf->validate_func = func;
}
int dgrambuf_recvmmsg(dgrambuf_t dbuf, int sockfd) {
void *dgram_base;
size_t vlen, i, dgram_index;
int recv_msg_count, res;
unsigned int seq, dgram_len;
if ( !dbuf->validate_func ) {
return -1;
}
/* Initialize recvmmsg() syscall arguments */
for (i=0, vlen=0; i < dbuf->dgram_count; i++) {
if ( dbuf->dgram_seq_numbers[i] == 0 ) {
dbuf->recv_iovecs[vlen].iov_base = dbuf->buf + i*dbuf->dgram_max_size;
dbuf->recv_iovecs[vlen].iov_len = dbuf->dgram_max_size;
memset(dbuf->msgs + vlen, 0, sizeof(struct mmsghdr));
dbuf->msgs[vlen].msg_hdr.msg_iov = dbuf->recv_iovecs + vlen;
dbuf->msgs[vlen].msg_hdr.msg_iovlen = 1;
vlen++;
}
}
/* Buffer is full, can't receive */
if ( vlen==0 ) {
return -2;
}
/* Do the syscall */
recv_msg_count = recvmmsg(sockfd, dbuf->msgs, vlen, MSG_WAITFORONE, NULL);
if (recv_msg_count < 0) {
perror("recvmmsg()");
return recv_msg_count;
}
/* Check all received messages */
res = 1;
for (i=0; i<recv_msg_count; i++) {
dgram_base = dbuf->recv_iovecs[i].iov_base;
dgram_index = (dgram_base - dbuf->buf) / dbuf->dgram_max_size;
dgram_len = dbuf->msgs[i].msg_len;
seq = dbuf->validate_func(dgram_len, dgram_base);
// TODO better feedback
if ( seq == 0 ) {
printf("#%zi invalid (%u)\n", i, seq);
dbuf->dgram_seq_numbers[dgram_index] = 0;
} else if ( seq == -1 ) {
printf("#%zi end\n", i);
dbuf->dgram_seq_numbers[dgram_index] = 0;
res = 0;
} else if ( seq < dbuf->win_base ) {
printf("#%zi past (%u)\n", i, seq);
dbuf->dgram_seq_numbers[dgram_index] = 0;
} else if ( seq >= dbuf->win_base + dbuf->dgram_count ) {
printf("#%zi future (%u)\n", i, seq);
dbuf->dgram_seq_numbers[dgram_index] = 0;
} else {
printf("#%zi valid (%u)\n", i, seq);
dbuf->dgram_seq_numbers[dgram_index] = seq;
dbuf->dgram_len[dgram_index] = dgram_len;
}
}
return res;
}
ssize_t dgrambuf_write(dgrambuf_t dbuf, int fd) {
size_t dgram_index, i, vlen;
unsigned int curr_seq, prev_seq, dgram_len;
ssize_t nwrite, total;
/* Initialize dgram_ordered_seq_numbers from dgram_seq_numbers */
for (i=0; i < dbuf->dgram_count; i++) {
dbuf->dgram_ordered_seq_numbers[i].index = i;
dbuf->dgram_ordered_seq_numbers[i].value = dbuf->dgram_seq_numbers[i];
}
/* Inplace sorting of dgram_ordered_seq_numbers */
qsort(dbuf->dgram_ordered_seq_numbers, dbuf->dgram_count, sizeof(struct uint_pair), _compare_uint_pair);
/* Initialize iovecs for writev, take dgram payloads following the sequence numbers */
for (prev_seq=0, vlen=0, total=0, i=0; i< dbuf->dgram_count; i++) {
curr_seq = dbuf->dgram_ordered_seq_numbers[i].value;
/* Skip empty dgram slot */
if ( curr_seq == 0 )
continue;
/* Skip dgram comming from the past */
if ( curr_seq < dbuf->win_base ) {
fprintf(stderr, "Oops : found dgram from past in buffer (%u)\n", curr_seq);
continue;
}
/* Break if first dgram to write is not in buffer at all */
if ( ( vlen==0 ) && (curr_seq != dbuf->win_base) ) {
fprintf(stderr, "Oops : nothing to write, missing %u seq\n", dbuf->win_base);
break;
}
/* Skip if next dgram is a dup */
if ( ( vlen > 0 ) && (curr_seq == prev_seq) ) {
continue;
}
/* Break if next seq dgram is missing */
if ( ( vlen > 0 ) && (curr_seq > prev_seq+1 ) ) {
break;
}
/* Normal case : curr_seq is the next dgram to write */
dgram_index = dbuf->dgram_ordered_seq_numbers[i].index;
dgram_len = dbuf->dgram_len[dgram_index] - dbuf->dgram_header_size;
dbuf->write_iovecs[vlen].iov_len = dgram_len; /* Setup iovecs */
dbuf->write_iovecs[vlen].iov_base = dbuf->buf + dgram_index*dbuf->dgram_max_size + dbuf->dgram_header_size;
dbuf->dgram_seq_numbers[dgram_index] = 0; /* Mark dgram slots about to be written out as reusable */
total += dgram_len; /* Update counters */
vlen++;
dbuf->win_base = curr_seq;
prev_seq = curr_seq;
}
/* If nothing valid to write out */
if ( vlen == 0 ) {
return -1;
}
nwrite = writev(fd, dbuf->write_iovecs, vlen);
if ( nwrite < 0 ) {
perror("writev()");
return nwrite;
}
if ( nwrite != total ) {
fprintf(stderr, "writev() short\n");
return nwrite;
}
return nwrite;
}
dgrambuf_t dgrambuf_new(size_t dgram_count, size_t dgram_max_size, size_t dgram_header_size) {
dgrambuf_t dbuf = calloc(1, sizeof(struct dgrambuf_t));
if (!dbuf) goto fail0;
dbuf->dgram_count = dgram_count;
dbuf->dgram_max_size = dgram_max_size;
dbuf->dgram_header_size = dgram_header_size;
dbuf->recv_iovecs = calloc(dgram_count, sizeof(struct iovec));
if (!dbuf->recv_iovecs) goto fail1;
dbuf->write_iovecs = calloc(dgram_count, sizeof(struct iovec));
if (!dbuf->write_iovecs) goto fail2;
dbuf->msgs = calloc(dgram_count, sizeof(struct mmsghdr));
if (!dbuf->msgs) goto fail3;
dbuf->win_base = 1;
dbuf->dgram_seq_numbers = calloc(dgram_count, sizeof(unsigned int));
if (!dbuf->dgram_seq_numbers) goto fail4;
dbuf->dgram_len = calloc(dgram_count, sizeof(ssize_t));
if (!dbuf->dgram_len) goto fail5;
dbuf->dgram_ordered_seq_numbers = calloc(dgram_count, sizeof(struct uint_pair));
if (!dbuf->dgram_ordered_seq_numbers) goto fail6;
dbuf->buf = calloc(dgram_count, dgram_max_size);
if (!dbuf->buf) goto fail7;
return dbuf;
fail7: free(dbuf->dgram_ordered_seq_numbers);
fail6: free(dbuf->dgram_len);
fail5: free(dbuf->dgram_seq_numbers);
fail4: free(dbuf->msgs);
fail3: free(dbuf->write_iovecs);
fail2: free(dbuf->recv_iovecs);
fail1: free(dbuf);
fail0: return 0;
}
void dgrambuf_free(dgrambuf_t *dbuf) {
if (dbuf && *dbuf) {
free((*dbuf)->buf);
free((*dbuf)->dgram_ordered_seq_numbers);
free((*dbuf)->dgram_len);
free((*dbuf)->dgram_seq_numbers);
free((*dbuf)->msgs);
free((*dbuf)->write_iovecs);
free((*dbuf)->recv_iovecs);
free(*dbuf);
}
*dbuf = NULL;
}
int _compare_uint_pair(const void *pa, const void *pb) {
const struct uint_pair *a = pa;
const struct uint_pair *b = pb;
if (a->value < b->value)
return -1;
else if ( a->value > b->value )
return 1;
else
return 0;
}
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