improve sse receiver

platform/sse_receiver.c

@@ -0,0 +1,181 @@
+// sse_receiver.c
+#include "sse_receiver.h"
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <stdio.h>
+#include <errno.h>
+
+#ifdef _WIN32
+  #include <winsock2.h>
+  #include <ws2tcpip.h>
+  #pragma comment(lib, "ws2_32.lib")
+  typedef SOCKET sock_t;
+  #define CLOSESOCK closesocket
+  #define sock_init() { WSADATA wsa; WSAStartup(MAKEWORD(2,2), &wsa); }
+  #define sock_cleanup() WSACleanup()
+#else
+  #include <unistd.h>
+  #include <fcntl.h>
+  #include <sys/types.h>
+  #include <sys/socket.h>
+  #include <netdb.h>
+  typedef int sock_t;
+  #define INVALID_SOCKET -1
+  #define CLOSESOCK close
+  #define sock_init()
+  #define sock_cleanup()
+#endif
+
+#define BUFFER_SIZE 4096
+
+struct tag_sse_receiver {
+    char host[256];
+    char port[16];
+    sock_t sock;
+    int connected;
+    char buffer[BUFFER_SIZE+1];    
+    size_t buf_len;
+    size_t line_len;
+    time_t next_attempt;
+};
+
+static void set_nonblocking(sock_t sock) {
+#ifdef _WIN32
+    u_long mode = 1;
+    ioctlsocket(sock, FIONBIO, &mode);
+#else
+    fcntl(sock, F_SETFL, fcntl(sock, F_GETFL, 0) | O_NONBLOCK);
+#endif
+}
+
+static int connect_and_handshake(SSE_RECEIVER *sse) {
+    struct addrinfo hints = {0}, *res = NULL;
+
+    hints.ai_family = AF_INET;
+    hints.ai_socktype = SOCK_STREAM;
+
+    if (getaddrinfo(sse->host, sse->port, &hints, &res) != 0) {
+        return 0;
+    }
+
+    sock_t sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
+    if (sock == INVALID_SOCKET) {
+        freeaddrinfo(res);
+        return 0;
+    }
+
+    if (connect(sock, res->ai_addr, (int)res->ai_addrlen) != 0) {
+        CLOSESOCK(sock);
+        freeaddrinfo(res);
+        return 0;
+    }
+
+    freeaddrinfo(res);
+
+    const char *req_fmt =
+        "GET /command HTTP/1.1\r\n"
+        "Host: %s\r\n"
+        "Accept: text/event-stream\r\n"
+        "Connection: keep-alive\r\n\r\n";
+
+    char req[512];
+    snprintf(req, sizeof(req), req_fmt, sse->host);
+    send(sock, req, (int)strlen(req), 0);
+
+    set_nonblocking(sock);
+    sse->sock = sock;
+    sse->buf_len = 0;
+    sse->line_len = 0;
+    sse->connected = 1;
+
+    return 1;
+}
+
+SSE_RECEIVER *sse_receiver_create(const char *host, const char *port) {
+    sock_init();
+    SSE_RECEIVER *sse = calloc(1, sizeof(SSE_RECEIVER));
+    strncpy(sse->host, host, sizeof(sse->host) - 1);
+    strncpy(sse->port, port, sizeof(sse->port) - 1);
+    sse->sock = INVALID_SOCKET;
+    sse->connected = 0;
+    sse->buf_len = 0;
+    sse->line_len = 0;
+    sse->next_attempt = 0;
+    return sse;
+}
+
+size_t find_sep(const char *buffer, size_t size, char sep) {
+    for (size_t i = 0; i < size; ++i) {
+        if (buffer[i] == sep) return i;
+    }
+    return size;
+}
+
+const char *sse_receiver_receive(SSE_RECEIVER *sse) {
+    while(1) {
+        size_t rm = sse->buf_len-sse->line_len;
+        if (rm) {
+            const char *r = sse->buffer+sse->line_len;
+            size_t sep = find_sep(r, rm, '\n');
+            if (sep < rm) {                
+                sep += sse->line_len;
+                sse->buffer[sep] = 0;
+                sse->line_len = sep+1;
+
+                if (strncmp(r,"data:",5) == 0) {
+                    r+=5;
+                    while (*r && isspace(*r)) ++r;
+                    if (*r) {
+                        return r;
+                    }
+                } 
+                continue;
+            }
+            if (r != sse->buffer) memmove(sse->buffer, r, rm);
+        } 
+        sse->line_len = 0;
+        sse->buf_len = rm;    
+
+        if (!sse->connected) {
+            time_t t = time(NULL);
+            if (t < sse->next_attempt) {
+                return NULL;
+            }
+            if (!connect_and_handshake(sse)) {
+                snprintf(sse->buffer, sizeof(sse->buffer) - 1, 
+                            "MESSAGE Failed to connect the command server %s:%s ", 
+                            sse->host, sse->port);
+                sse->next_attempt = t+5;
+                return sse->buffer;
+            } else {
+                return "MESSAGE Connected to command server";
+            }
+        }
+
+        int n = recv(sse->sock, sse->buffer + sse->buf_len, (int)(BUFFER_SIZE - sse->buf_len), 0);
+        if (n <= 0) {
+#ifdef _WIN32
+            int err = WSAGetLastError();
+            if (err != WSAEWOULDBLOCK && err != WSAEINPROGRESS)
+#else
+            if (errno != EWOULDBLOCK && errno != EAGAIN)
+#endif
+            {
+                CLOSESOCK(sse->sock);
+                sse->connected = 0;
+            }
+            return NULL;
+        }
+
+        sse->buf_len += n;
+    } 
+}
+
+void sse_receiver_destroy(SSE_RECEIVER *sse) {
+    if (sse->connected) {
+        CLOSESOCK(sse->sock);
+    }
+    free(sse);
+    sock_cleanup();
+}