implemented UDP backend

src/udp_backend/Makefile

@@ -0,0 +1,15 @@
+CFLAGS=-ggdb -Wall
+
+all: test udp_backend.a
+
+clean:
+	rm -f *.o *.a udp_backend_test
+
+test: udp_backend_test
+
+udp_backend.a: udp_backend.o 
+	$(AR) -rcv $@ $?
+
+udp_backend_test: udp_backend.c 
+	$(CC) $(CFLAGS) -D_TEST -o $@ $?
+

src/udp_backend/udp_backend.c

@@ -0,0 +1,192 @@
+/*
+Copyright (c) 2020 Gérald Colangelo <gcolangelo@ospow.com>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <arpa/inet.h>
+#include <errno.h>
+#include "../smart_records_internals.h"
+#include "udp_backend_internals.h"
+
+void *udp_backend_init(char **error)
+{
+    udp_backend_ctx_t *ctx=NULL;
+    ctx = malloc(sizeof(udp_backend_ctx_t));
+    memset(ctx, 0, sizeof(udp_backend_ctx_t));
+    return ctx;
+}
+
+int udp_backend_open_records_base(void *ctx, char **error, const char *uri)
+{
+    udp_backend_ctx_t *c;
+    char *host;
+    int port, conv;
+    if (!ctx || !uri) {
+        set_error_and_fails("invalid arguments while opening records base");
+    }
+    c = (udp_backend_ctx_t *)ctx;
+
+	// URL is basically udp://host:port/
+    conv = sscanf(uri,"udp://%m[^:]:%d", &host, &port);
+    if(conv != 2) {
+        set_error_and_fails("bad URI");
+    }
+    if ((c->socket = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
+        set_error_and_fails("failed creating UDP socket");
+    }
+    c->sa.sin_family = AF_INET;
+    c->sa.sin_port = htons(port);
+    // XXX: Implement both IP address and hostname as input
+    if (inet_aton(host, &(c->sa.sin_addr)) < 0) {
+        set_error_and_fails("failed creating sockaddr_in structure: did you provided a hostname?");
+    }
+    if (connect(c->socket, &c->sa, sizeof(struct sockaddr_in)) < 0) {
+        set_error_and_fails(strerror(errno));
+    }   
+    return 0;
+failed:
+    return -1;
+}
+
+int udp_backend_set_format(void *ctx, char **error, const char *fmt)
+{
+    udp_backend_ctx_t *c;
+    if (!ctx || !fmt) {
+        set_error_and_fails("invalid parameters while setting format.")
+    }
+    c = (udp_backend_ctx_t *) ctx;
+    c->fmt = strdup(fmt);
+    return 0;
+failed:
+    return -1;
+}
+
+int udp_backend_write_record(void *ctx, char **error, ...)
+{
+    udp_backend_ctx_t *c;
+    char *pkt;
+    int size=0, ret=0;
+    va_list ap;
+
+    if (!ctx) {
+        set_error_and_fails("invalid parameters while setting format.")
+    }
+    c = (udp_backend_ctx_t *) ctx;
+
+    if (!c->fmt) {
+        set_error_and_fails("no format provided, please set it before writing any record");
+    }
+
+    va_start(ap,error);
+    size = vsnprintf(NULL, size, c->fmt, ap);
+    va_end(ap);
+
+    va_start(ap,error);
+    pkt = malloc(sizeof(char) * (size +1));
+    if (vsprintf(pkt, c->fmt, ap) != size) {
+        set_error_and_fails("failed converting input to message");
+    }
+    va_end(ap);
+    if ((ret = write(c->socket, pkt, size)) != size) {
+        printf("--> ret=%d\n",ret);
+        set_error_and_fails( ret < 0 ? strerror(errno) : "Incomplete data sent");
+    }
+    free(pkt);
+    return 0;
+failed:
+    free(pkt);
+    return -1;
+}
+
+int udp_backend_close_records_base(void *ctx)
+{
+    udp_backend_ctx_t *c;
+    if(!ctx)
+        return -1;
+    c = (udp_backend_ctx_t *)ctx;
+
+	if(c->socket > 0)
+		close(c->socket);
+    if(c->fmt)
+        free(c->fmt);
+    free(c);
+
+    return 0;
+}
+
+
+
+#ifdef _TEST
+
+#define dump_error_and_quit(func,error) \
+        { \
+            if (error) { \
+                fprintf(stderr, "[ERROR] %s(): %s\n", func, error); \
+            } else { \
+                fprintf(stderr, "[ERROR] %s(): unknown error\n", func); \
+            } \
+            free(error); \
+            exit(EXIT_FAILURE); \
+        }
+
+
+int main(int ac, char **av)
+{
+    void *ctx;
+    char *error=NULL;
+    int i=0;
+
+    if(ac != 2) {
+        printf("Usage: %s <mysql_uri>\n \
+            mysql_uri format is mysql://user[:password]@host[:port]/database.table\n \
+            database shall exists and table must obey the following scheme:\n \
+            CREATE TABLE <table> (a INT, b INT, c VARCHAR(40))\n",av[0]);
+        exit(EXIT_FAILURE);
+    }
+
+    ctx = udp_backend_init(&error);
+    if (ctx == NULL) {
+        dump_error_and_quit("udp_backend_init", error);
+    }
+
+    if (udp_backend_set_format(ctx, &error, "%d;%d;%s;\n") < 0){
+        dump_error_and_quit("udp_backend_set_format", error);
+    }
+
+    if(udp_backend_open_records_base(ctx, &error, av[1]) < 0) {
+        dump_error_and_quit("udp_backend_set_open_records_base", error);
+    }
+
+    for (i=0; i<4; i++) {
+        if (udp_backend_write_record(ctx, &error, i, i+10, "Text here") <0 ){
+            dump_error_and_quit("udp_backend_write_record", error);
+        }
+    }
+    udp_backend_close_records_base(ctx);
+}
+#endif

src/udp_backend/udp_backend.h

@@ -0,0 +1,13 @@
+#ifndef _SMART_RECORDS_UDP_BACKEND_H
+#define _SMART_RECORDS_UDP_BACKEND_H
+
+#include <stdarg.h>
+
+
+void *udp_backend_init(char **error);
+int udp_backend_open_records_base(void *ctx, char **error, const char *uri);
+int udp_backend_write_record(void *ctx, char **error, va_list ap);
+int udp_backend_set_format(void *ctx, char  **error, const char *format);
+int udp_backend_close_records_base(void *ctx);
+
+#endif

src/udp_backend/udp_backend_internals.h

@@ -0,0 +1,10 @@
+#ifndef UDP_BACKEND_INTERNALS_H
+#define UDP_BACKEND_INTERNALS_H
+
+typedef struct udp_backend_ctx_t {
+    int socket;
+    struct sockaddr_in sa;
+	char *fmt;
+} udp_backend_ctx_t;
+
+#endif